Validity of the sonographic measurement of the diameters of the ascending aorta in rats

PURPOSE

The objective of this investigation was to compare transthoracic ultrasound (US) determinations of ascending aortic diameters in rats with video microscopy (VM), the current standard for measuring aortic diameters in rats.

MATERIALS AND METHODS

The diameter of the ascending aorta was measured in 111 adult Lewis male rats, by VM and US, with a 9 MHz probe, before and after intervention for induction of experimental aneurysm of the ascending aorta.

RESULTS

The Bland-Altman test showed a high degree of agreement between the two methods, with a bias of only 0.23 mm (95 % confidence limits - 0.86 - 0.39 mm). Also, the measurements obtained by US correlated highly (r = 0.83, p < 0.0001) with those obtained by VM. Rat ascending aortic diameters obtained both by VM and US correlated significantly with the weight (r = 0.62 and r = 0.39, respectively), and with the age of the animals (r = 0.74 and r = 0.49, respectively).

CONCLUSION

This study demonstrates that noninvasive US ascending aortic measurements are a reliable supplement to VM for the development of an ascending aortic aneurysm model, and for monitoring the efficiency of novel therapeutic agents.

Closed drainage using redon catheters for poststernotomy mediastinitis: results and risk factors for adverse outcome

BACKGROUND

Several different surgical techniques have been described for the treatment of poststernotomy mediastinitis. The present study was undertaken to evaluate the midterm results of primary closed drainage using Redon catheters and to identify risk factors for adverse outcome.

METHODS

Hospital records of 72 patients in whom poststernotomy mediastinitis developed and who underwent closed drainage with Redon catheters between April 1, 1996, and December 31, 1999, were reviewed. Follow-up was complete and averaged 11.8 +/- 11.5 months.

RESULTS

Of the 25 deaths (34.7%) recorded, 15 were directly attributable to mediastinitis. Actuarial estimates for freedom from mediastinitis-related death were 80.1% at 1 month and 77.4% at 1 year, 2 years, and 3 years. Logistic regression identified older age (odds ratio, 1.1; 95% confidence interval, 1.02 to 1.18), incubation time of 14 days or less (6.5; 1.33 to 31.4), and methicillin-resistant Staphylococcus aureus (5.8; 1.2 to 27.2) as independent risk factors for mediastinitis-related death. Reintervention for recurrent mediastinitis was necessary in 9 patients (12.5%) and occurred at a mean interval of 18.7 +/- 13.5 days from the first debridement. Actuarial estimates for freedom from reintervention were 87.1% at 1 month and 85.2% at 1 year, 2 years, and 3 years. The combined end point of treatment failure (mediastinitis-related death or reintervention) was recorded in 9 patients (26.4%). Actuarial estimates for freedom from treatment failure were 74.3% at 1 month and 72.7% at 1 year, 2 years, and 3 years. Logistic regression identified older age (1.01; 1.02 to 1.18), preoperative renal insufficiency (6.8; 1.04 to 44.5), and methicillin-resistant S aureus infection (4.8; 1.04 to 22.33) as independent risk factors for treatment failure (includes mediastinitis-related death and reintervention [with or without death]).

CONCLUSIONS

Primary closed drainage using Redon catheters is an effective and simple treatment for most patients in whom poststernotomy mediastinitis develops. However, patients with methicillin-resistant S aureus infection or recurrent mediastinitis may benefit from a more aggressive approach.

Risk factors for post-cardiopulmonary bypass vasoplegia in patients with preserved left ventricular function

BACKGROUND

Although vasodilatory shock (VS) is one of the main complications of cardiopulmonary bypass (CPB), its pathophysiologic basis remains unclear. The aim of this study was to identify predisposing factors for the development of VS after CPB independent of ventricular function.

METHODS

Thirty-six patients undergoing coronary artery bypass grafting who developed VS were compared with 72 control patients without post-CPB cardiogenic or vasoplegic shock, in a 2:1 case control study. Patients and controls underwent the same anesthetic protocol and were matched by age, sex, operation date, and left ventricle ejection fraction.

RESULTS

Preoperative and intraoperative patient characteristics were not significantly different between the two groups. Preoperative use of angiotensin-converting enzyme inhibitors and intravenous heparin were independent predictors for post-CPB VS by multivariate analysis (relative risk of 2.26 and 2.78, respectively). Intensive care unit stay and hospital stay were significantly longer in VS cases than controls, without any difference in early postoperative mortality.

CONCLUSIONS

The only independent risk factors for postoperative VS identified were preoperative use of angiotensin-converting enzyme inhibitors and intravenous heparin. These risk factors were independent of age, gender, anesthetic protocol, and left ventricle ejection fraction.

Effect of variation in systemic blood flow on plasma TNF-alpha in a pig model with left ventricular assist device

Tumor necrosis factor-alpha (TNF-alpha) release has been implicated in a sepsis-like syndrome following cardiopulmonary bypass (CPB). This also may be important in patients who have had a left ventricular assist device (LVAD) implanted. This report investigates the effect of reducing systemic blood flow on hemodynamic response, mixed venous oxygen saturation (SvO(2)), and the release of TNF-alpha. LVADs were implanted in 9 pigs. The aorta was clamped, and thus the LVAD flow represented the entire systemic blood flow. Plasma TNF-alpha in the femoral artery (FA) and superior mesenteric vein (SMV) was measured at baseline and following systemic blood flow changes. Simultaneously, hemodynamic parameters and oxygen saturation in the pulmonary artery (SvO(2)) were measured. Following reductions in systemic blood flow, plasma TNF-alpha increased gradually to a maximum level at a systemic blood flow of 20%. There was no significant difference between TNF-alpha levels in the SMV and the FA. There was a significant (p < 0.05) correlation between cardiac index, stroke volume index, and TNF-alpha. The SvO(2) decreased significantly (p < 0.05) at a systemic blood flow of 30 and 20%. A rise in TNF-alpha occurred when the SvO(2) was less than 75%. The data demonstrate that a reduction in systemic blood flow causes an increase in plasma TNF-alpha. This can lead to the development of a sepsis-like syndrome in a group of patients who already are hemodynamically compromised. While weaning short-term LVAD support, rapid diminution of the cardiac output and the pump flow must be avoided.

Mechanical circulatory support for advanced heart failure: effect of patient selection on outcome

BACKGROUND

Use of wearable left ventricular assist systems (LVAS) in the treatment of advanced heart failure has steadily increased since 1993, when these devices became generally available in Europe. The aim of this study was to identify in an unselected cohort of LVAS recipients those aspects of patient selection that have an impact on postimplant survival.

METHODS AND RESULTS

Data were obtained from the Novacor European Registry. Between 1993 and 1999, 464 patients were implanted with the Novacor LVAS. The majority had idiopathic (60%) or ischemic (27%) cardiomyopathy; the median age at implant was 49 (16 to 75) years. The median support time was 100 days (4.1 years maximum). Forty-nine percent of the recipients were discharged from the hospital on LVAS; they spent 75% of their time out of the hospital. For a subset of 366 recipients, for whom a complete set of data was available, multivariate analysis revealed that the following preimplant conditions were independent risk factors for survival after LVAS implantation: respiratory failure associated with septicemia (odds ratio 11.2), right heart failure (odds ratio 3.2), age >65 years (odds ratio 3.01), acute postcardiotomy (odds ratio 1.8), and acute infarction (odds ratio 1.7). For patients without any of these factors, the 1-year survival after LVAS implantation including the posttransplantation period was 60%; for the combined group with at least 1 risk factor, it was 24%.

CONCLUSIONS

Careful selection, specifically implantation before patients become moribund, and improvement of management may result in improved outcomes of LVAS treatment for advanced heart failure.

Intestinal tissue oxygenation and tumor necrosis factor-alpha release during systemic blood flow changes in pigs with left ventricular assist devices

We previously demonstrated that tumor necrosis factor-alpha (TNF-alpha) increased following a reduction in systemic blood flow to 60% or less of the original cardiac output using a left ventricular assist device (LVAD). The aim of this study was to investigate the effect of reducing systemic blood flow on tissue oxygenation in the gastrointestinal tract (GIT) and the consequences of this on TNF-alpha release. LVADs were implanted in 9 pigs. The aorta was clamped, and thus the LVAD flow represented the entire systemic blood flow. Plasma TNF-alpha of the superior mesenteric vein was measured at baseline and during systemic blood flow changes. Simultaneously, pH, lactate, oxygen delivery index (DO(2)I), oxygen consumption index (VO(2)I), and oxygen extraction (O(2)ER) in the GIT were measured. The pH decreased and the lactate level increased significantly (p < 0.05) at a systemic blood flow of 50% or less. The VO(2)I was positively correlated with DO(2)I. The O(2)ER increased significantly (p < 0.05) with reductions in systemic blood flow to 30% or less. There was a significant (p < 0.01) correlation between TNF-alpha and O(2)ER at levels higher than 55%. These data demonstrate that the GIT oxygenation is inadequate with a reduction in systemic blood flow to 50% and that GIT oxygenation becomes critical at a reduction of 30%. During LVAD weaning, careful attention must be given to the GIT. The pH and lactate may be good markers of the adequacy of tissue oxygenation in the GIT.

Long-term mechanical circulatory support with the wearable Novacor left ventricular assist system

OBJECTIVE

As of July 1st 1999, 36 European patients have lived for more than 1 year supported by the Novacor wearable electric left ventricular assist system (LVAS). All were unresponsive to maximum medical therapy, prior to implantation. These patients offer an unique opportunity to evaluate the feasibility of long-term ambulatory mechanical circulatory support as a therapeutic option for patients in profound cardiac failure.

METHODS

Data was obtained from the Novacor European Registry.

RESULTS

At the time of implantation, median age was 55 (18-67) years. Aetiology was ischemic (9, 25%) or idiopathic (26, 72%) cardiomyopathy, and myocarditis (1, 3%). Median duration of LVAS support was 1.49 (1. 03-4.10) years. Eight recipients had LVAS support times >2 years, of which two were >3 years and one >4 years. The median time spent outside the hospital was 1.27 (0.58-3.83) years, representing 82% of the duration of LVAS support. No mechanical failure was observed during the entire observation period. One pump was replaced electively after 3.67 years due to pump driver wear-out. Twelve patients (33%) are currently on support while 17 were transplanted (14, 39%) or weaned (3, 8%). Seven (19%) patients died after a median of 1.24 years circulatory support.

CONCLUSIONS

Experience with long-term Novacor LVAS recipients has demonstrated effective rehabilitation in this group of patients with refractory advanced heart failure. This suggests that LVAS therapy may offer a safe and realistic option for patients for whom no other effective therapy is available. The patient sub-population that would benefit most from this therapy remains to be defined.

[External ventricular support in primary cardiogenic shock]

Primary cardiogenic shock is a common condition with a high mortality rate. In this indication, mechanical assist plays an important part and has improved a lot over the last decade. The authors report their experience with the same assist device in patients with primary cardiogenic shock. Nineteen patients (9 dilated cardiomyopathies, 7 myocardial infarctions, 2 myocardities, 1 undetermined) were treated with an external mechanical ventricular assist device (Thoratec, Berkeley, U.S.). Fourteen patients received a biventricular assist and 5 had a uni-left ventricular assist device. Four of the 19 patients were completely weaned off their ventricular assist after 13, 27, 36 and 94 days, respectively. Ten patients underwent transplantation after an average of 43 days (range 8-95 days). Of the 19 patients, 7 had a portable console allowing autonomous ambulation. Five patients died under mechanical assistance (26.9%) and 3 patients died after transplantation. Three patients required temporary haemodialysis; 4 suffered embolic complications; 4 had mediastinal haemorrhages; 4 had bleeding from other sites, and 6 suffered from late tamponnade. Fourteen patients had at least one infectious episode. The authors conclude that, in patients referred for severe primary cardiogenic shock, the implantation of an external biventricular assist is a reliable option, allowing sequential weaning or being a bridge to transplantation in non-dependent patients, providing they are severely selected.

Myocardial recovery after mechanical support for acute myocarditis: is sustained recovery predictable?

BACKGROUND

At present, myocardial recovery with mechanical support for acute myocarditis is a more frequently observed issue. However, predictive parameters of a sustained myocardial recovery are still under investigation.

METHODS

Two recent cases of mechanical support for acute lymphocytic myocarditis with two different outcomes are reported. Literature about this disease and predictability of a sustainable myocardial recovery are reviewed.

RESULTS

Acute lymphocytic myocarditis is an individual entity whose outcome is associated with the importance of healed cell damage. Unfortunately, there are no available means of quantifying the fibrotic scar and endomyocardial biopsy has a high percentage of false-negative results. Echocardiographic assessment of systolic and diastolic cardiac function is difficult while under mechanical support and its significance is not obvious. Forthcoming development of Doppler could better correlate myocardial contractility and histology to be predictive of a sustained recovery after acute myocarditis under mechanical support.

CONCLUSIONS

Long-lasting recovery after mechanical support for acute myocarditis remains unpredictable in our experience. More predictive factors are needed.

Pseudointima in inflow conduits of left ventricular assist devices

BACKGROUND

Explant analysis of left ventricular assist systems (LVAS) should permit a better evaluation of long-term evolution of materials and tissue healing in patients supported by mechanical devices and a precise understanding of embolic phenomena, observed clinically.

METHODS

Five Novacor LVAS and their conduits have been explanted after 156 days (range 61-226 days) of mechanical support. The pseudo-intima (PI) developed in the inflow and outflow conduits was characterized microscopically, using monoclonal antibodies.

RESULTS

The morphological aspects of PI were quite different in the inflow and outflow conduits. Blood coagulation between the basal surface of the PI and the Dacron tube, irregular collagen type I matrix with plasma infiltration, macrophages, and neutrophil granulocyte elastase characterized the nonadherent, loose, and potentially thrombogenic PI growth in the inflow conduit. The PI from collagen types I and IV with circumferentially oriented alpha-smooth muscle cell actin-positive cells was anchored to the outflow conduits.

CONCLUSIONS

The observations, which have to be confirmed by a more extensive study on a larger number of specimens, suggest the role of the biomaterial itself, as well as the configuration, physical characteristics, and rheology in the conduit. They also suggest that thromboembolic complications of LVAS may eventually be related to this host tissue response.

The European experience of Novacor left ventricular assist (LVAS) therapy as a bridge to transplant: a retrospective multi-centre study

OBJECTIVE

Artificial heart devices have suffered from a negative press based on the early Jarvik experience of the 1980s. This is in stark contrast to realities of current left ventricular assist (LVAS) therapy. The Novacor N100 PC wearable left ventricular assist system (LVAS) was introduced in Europe in late 1993. This system allows implanted recipients to be completely autonomous with the system controlled by a small computer and powered by rechargeable batteries. This report represents the initial European experience with the Novacor LVAS.

METHODS

Since the system was introduced with regulatory approval as a commercial product, clinicians were not bound by the constraints of a study protocol and only minimal data were collected. This report presents the results of a retrospective study of 118 consecutive patients who had the LVAS implanted as a bridge to transplant, in 19 centres over the three year period ending in November 1996.

RESULTS

Mortality and morbidity varied widely between centres. The median implant time was 115 days (0-585 days) and 33% of patients returned home, supported by the LVAS. The overall survival on LVAS was 64%. The major causes of death were infection (14%) and MOF (6%). There were no significant device or system failures despite a cumulative patient experience of 24.8 years outside of a hospital environment. Patient selection and management varied greatly between centres and this was reflected in disparate outcomes.

CONCLUSIONS

Optimal selection and management of LVAS patients has still to be established. While the data available for this report lacked the detail necessary to demonstrate direct causal relationships between selection and management, it was clear from the inter-centre differences that these two factors have a major impact on outcomes. This early experience has directed attention towards improved management regimes. Given the results obtained from the best centres and the ability to discharge patients to lead near-normal lives in the community, the authors believe that the Novacor LVAS now offers a real therapeutic alternative for selected end-stage heart failure patients for whom a donor heart is unavailable or who are unsuitable for transplantation.

Inflammatory response to cardiopulmonary bypass using roller or centrifugal pumps

BACKGROUND

The inflammatory response in 29 patients undergoing coronary artery bypass grafting using either roller or centrifugal (CFP) pumps was evaluated in a prospective study.

METHODS

Patients were randomized in roller pump (n = 15) and CFP (n = 14) groups. Terminal complement complex activation (SC5b-9) and neutrophil activation (elastase) were assessed during the operation. Cytokine production (tumor necrosis factor-alpha, interleukin-6, interleukin-8) and circulating adhesion molecules (soluble endothelial-leukocyte adhesion molecule-1 and intercellular adhesion molecule-1) were assessed after the operation.

RESULTS

Release of SC5b-9 after stopping cardiopulmonary bypass and after protamine administration was higher in the CFP group (p = 0.01 and p = 0.004). Elastase level was higher after stopping cardiopulmonary bypass using CFP (p = 0.006). Multivariate analysis confirmed differences between roller pump and CFP groups in complement and neutrophil activation. After the operation, a significant production of cytokines was detected similarly in both groups, with peak values observed within the range of 4 to 6 hours after starting cardiopulmonary bypass. However, interleukin-8 levels were higher using CFP 2 hours after starting cardiopulmonary bypass (p = 0.02). Plasma levels of adhesion molecules were similar in both groups within the investigation period.

CONCLUSIONS

During the operation, CFP caused greater complement and neutrophil activation. After the operation, the inflammatory response was similar using either roller pump or CFP.

Inflammatory response to cardiopulmonary bypass using two different types of heparin-coated extracorporeal circuits

Previous reports have highlighted the disparity in biocompatibility of two differently engineered heparin coatings during the cardiopulmonary bypass (CPB) procedure. The aim of this prospective study was to evaluate the impact of the difference in haemocompatibility provided by either the Duraflo II equipment or the Carmeda equipment in the terminal inflammatory response observed after coronary artery surgery. Thirty patients were randomly allocated to two groups to be operated on using either Duraflo II equipment (group I) or Carmeda equipment (group 2) for extracorporeal circulation (ECC). Initial inflammatory response was assessed by terminal complement complex activation (SC5b-9). The late inflammatory response observed in the postoperative period was assessed by measuring cytokine production (tumour factor necrosis (TNF alpha), interleukin IL-6, interleukin IL-8) and circulating concentrations of adhesion molecules (ELAM-1, ICAM-1). The release of SC5b-9 after CPB and after protamine administration was lower in group 2 than in group 1 (p = 0.0002 and p = 0.006, respectively). A significant production of cytokines was detected in both groups with peak values observed within the time range of 4-6 h after the start of CPB.

Measures to control blood activation during assisted circulation

Major improvements in heart assist devices have allowed prolonged mechanical circulatory support with successful subsequent weaning or heart transplantation. The contact of blood with biomaterials used in life-sustaining devices and numerous biomaterial-independent factors elicit a systemic inflammatory response, which involves activation of various plasma protein systems and blood cells. Prolonged mechanical circulatory support elicits a systemic inflammatory response and hemostatic perturbations similar to that reported during cardiopulmonary bypass. However, in the setting of prolonged assistance, time has a complex and ill-known influence on blood activation. Methods to reduce blood activation during prolonged assisted circulation are derived from cardiopulmonary bypass investigations. Improving the biocompatibility of artificial devices can be achieved either by biomaterial surface modifications, by inhibition of biologic cascades leading to blood activation, or by controlling end points of biologic cascades. However, the necessity to respect the integrity of the organism during prolonged assistance precludes most systemic interventions and limits the control of blood activation to the area of the device.

Preconditioning with cromakalim improves long-term myocardial preservation for heart transplantation

BACKGROUND

Myocardial preservation for heart transplantation relies on hyperkalemic cardiac arrest and hypothermic storage. Our study investigated whether pretreatment with a potassium-channel opener (cromakalim) before prolonged storage in an extracellular fluid improves left ventricular recovery.

METHODS

Rabbit hearts were submitted to 6-hours' cold storage and assessed on a blood-perfused isolated heart preparation. Hemodynamic recovery, enzyme release (creatine kinase and lactate dehydrogenase), and adenine nucleotide content were determined. Five groups were tested: control (n=6), no ischemia; UW group (n=7), hearts arrested with and stored in University of Wisconsin solution; STH group (n=5), hearts arrested with and stored in St. Thomas' Hospital solution; cromakalim group (n=6), hearts pretreated with cromakalim (30 microg/kg) before arrest with and storage in St. Thomas' Hospital solution; and glibenclamide group (n=5), hearts pretreated with cromakalim followed by glibenclamide (a potassium-channel blocker) before arrest with and storage in St. Thomas' Hospital solution.

RESULTS

Hemodynamic recovery was improved and enzyme release was lower in the UW group than in the STH group. Compared with the STH group, the group pretreated with cromakalim had significantly decreased left ventricular end-diastolic pressures, increased left ventricular developed pressures, increased maximal values of positive and negative rates of rise of left ventricular pressure, and increased time constant of isovolumetric relaxation. Hemodynamic recovery was similar in the UW group and cromakalim groups. Glibenclamide did not abolish the effects of cromakalim. None of the protocols affected myocardial energy stores.

CONCLUSION

Pretreatment with cromakalim affords additional protection to that provided by cardioplegic arrest and prolonged cold storage using an extracellular solution. The intracellular mechanisms involved remain to be determined.

Cardiac operations in octogenarians: perioperative risk factors for death and impaired autonomy

BACKGROUND

With the progressive aging of western populations, cardiac surgeons are increasingly faced with elderly patients.

METHODS

We reviewed the records of 191 consecutive patients aged 80 years or older (mean age, 83 +/- 2.4 years) who underwent a cardiac surgical procedure at our institution from 1991 through 1996.

RESULTS

Ninety-eight patients were men. Preoperatively, 32% of patients were in New York Heart Association class III or IV, and mean left ventricular ejection fraction was 0.55 +/- 0.02. One hundred ten patients (58%) underwent aortic valve replacement, 47 (25%) had coronary artery bypass grafting, 26 (14%) had combined aortic valve replacement and coronary artery bypass grafting, 5 (3%) underwent mitral valve replacement, and 3 (1.6%) had other procedures. Postoperative complications occurred in 69.1% of patients. The hospital mortality rate was 16.2%. Actuarial survival estimates at 1 year, 3 years, and 5 years were 79.2%, 74.9%, and 56.2%, respectively. Multivariate predictors (p < 0.05) of hospital death were preoperative pulmonary hypertension and lower left ventricular ejection fraction. Multivariate predictors of late death were combined aortic valve replacement and coronary artery bypass grafting and female sex. Sixty-four percent of long-term survivors were fully autonomous, and female sex was the only independent predictor of impaired autonomy. Eighty-three percent of survivors were satisfied with their present quality of life.

CONCLUSIONS

Cardiac operations can be performed in octogenarians with a favorable long-term outcome. Earlier referral and intervention is mandatory to improve results in this patient population.

Pretransplantation risk factors for death after heart transplantation: the Henri Mondor experience

BACKGROUND AND METHODS

Risk factors for death after primary heart transplantation were identified by analyzing our total experience with 234 patients who underwent transplantation at our institution from May 28, 1979, to May 27, 1996.

RESULTS

There were 205 male and 29 female patients. Mean recipient age was 48.5+/-10.9 years (standard deviation). Recipient diagnosis included ischemic cardiomyopathy in 103 (44%), idiopathic cardiomyopathy in 98 (42%), valvular heart disease in 17 (7%), congenital heart disease in 4 (2%), and other diagnoses in 12 (5%) patients. Donor age was 32+/-10.2 years. Graft ischemic time was 138.1+/-51.8 minutes. The operative mortality rate was 23.5%. Actuarial survival estimates for all patients at 1, 5, and 10 years were 62%, 50%, and 44%, respectively. The three most common causes of death (both early and late) after primary heart transplantation were infection (27.4%), acute rejection (18.9%), and early graft failure (17.9%). Multivariate logistic regression analysis identified older recipient age (p = 0.007), higher preoperative pulmonary vascular resistance (p = 0.01), recipient preoperative hepatic insufficiency (p = 0.001), and gender mismatch (p = 0.02) as independent predictors of early death (within 3 months of the procedure). Multivariate proportional hazard regression analysis revealed that recipient idiopathic cardiomyopathy (p = 0.02) and recipient preoperative liver failure (p = 0.01) were independent risk factors for late death (after 3 months).

CONCLUSION

These results underscore the importance of adequate recipient selection and recipient/donor matching for short- and long-term survival after primary heart transplantation.

Heparin coating of extracorporeal circuits inhibits contact activation during cardiac operations

OBJECTIVE

Heparin coating reduces complement activation on the surface of extracorporeal circuits. In this study we investigated its effect on activation of the contact system in 30 patients undergoing coronary artery bypass grafting with the use of a heparin-coated (Duraflo II, Baxter Healthcare Corp., Edwards Division, Santa Ana, Calif.; n = 15) or an uncoated extracorporeal circuit (n = 15).

METHODS

Plasma markers that reflect activation of contact (kallikrein-C1-inhibitor complexes), coagulation (prothrombin fragments F1 + 2), or fibrinolytic (plasmin-alpha 2-antiplasmin complexes) systems were determined before and during the operation. The generation of kallikrein-C1-inhibitor complexes was reduced by 62% (p = 0.06) after the onset of cardiopulmonary bypass and by 43% (p = 0.026) after the cessation of bypass in the group in which a heparin-coated circuit was used compared with the group in which the circuit was uncoated. Generation was reduced by 58% (p = 0.06) when the ratio of kallikrein-C1-inhibitor to prekallikrein after onset of bypass was considered. We detected significant increases in F1 + 2 levels in both groups and increases in plasmin-alpha 2-antiplasmin complexes in the heparin-coated group at cessation of bypass, but no intergroup differences were observed. Thus use of heparin-coated extracorporeal circuits during cardiac operations reduces formation of kallikrein-C1-inhibitor complexes when compared with use of uncoated circuits. The heparin coating is not accompanied by similar reductions in coagulation or fibrinolysis, suggesting that thrombin and plasmin formation during cardiopulmonary bypass occurs mainly independently of the contact system activation.

Clinical evaluation of Duraflo II heparin treated extracorporeal circulation circuits (2nd version). The European Working Group on heparin coated extracorporeal circulation circuits

OBJECTIVES

To evaluate whether the application of heparin treated circuits for elective coronary artery surgery improves postoperative recovery, a European multicenter randomised clinical trial was carried out.

METHODS

In 11 European heart centers, 805 low-risk patients underwent cardiopulmonary bypass (CPB) with either an untreated circuit (n = 407) or an identical but heparin treated circuit (n = 398, Duraflo II).

RESULTS

Significant differences were found among participating centers with respect to patient characteristics, blood handling procedures and postoperative care. The use of heparin treated circuits revealed no overall changes in blood loss, blood use, time on ventilator, occurrence of adverse events, morbidity, mortality, and intensive care stay. These results did not change after adjustment for centers and (other) prognostic factors as analysed with logistic regression. In both groups no clinical or technical (patient or device related) side effects were reported. Because female gender and aortic cross clamp time appeared as prognostic factors in the logistic regression analysis, a subgroup analysis with these variables was performed. In a subpopulation of females (n = 99), those receiving heparin treated circuits needed less blood products, had a lower incidence of rhythm disturbances and were extubated earlier than controls. In another subgroup of patients with aortic cross clamp time exceeding 60 min (n = 197), the amount of patients requiring prolonged intensive care treatment (> 24 h) was significantly lower when they received heparin treated circuits versus controls.

CONCLUSION

These findings suggest that improved recovery can be expected with heparin treated circuits in specific higher risk patient populations (e.g. females) and when prolonged aortic cross clamp time is anticipated. Further investigations are recommended to analyses the clinical benefit of heparin treated circuits in studies with patients in different well defined risk categories and under better standardised circumstances.

Heparin coating with aprotinin reduces blood activation during coronary artery operations

BACKGROUND

This study was performed to evaluate whether the combination of heparin-coated extracorporeal circuits (ECC) and aprotinin treatment reduce blood activation during coronary artery operations.

METHODS

Sixty patients were prospectively divided into two groups (heparin-coated ECC and uncoated ECC groups), which were comparable in terms of age, sex, left ventricular function, preoperative aspirin use and consequent intraoperative aprotinin use, number of grafts, duration of aortic cross-clamping, and duration of cardiopulmonary bypass. Blood activation was assessed at different times during cardiopulmonary bypass by determination of complement activation (C3 and C4 activation products C3b/c and C4b/c and terminal complement complex), leukocyte activation (elastase), coagulation (scission peptide fibrinopeptide 1 + 2), and fibrinolysis (D-dimers).

RESULTS

Univariate analysis showed that heparin-coated ECC, under conditions of standard heparinization, did not reduce perioperative blood loss and need for transfusion. Heparin coating, however, reduced maximum values of C3b/c (446 +/- 212 nmol/L versus 632 +/- 264 nmol/L with uncoated ECC; p = 0.0037) and maximum C4b/c values (92 +/- 48 nmol/L versus 172 +/- 148 nmol/L with uncoated ECC; p = 0.0069). Levels of terminal complement complex, elastase, fibrinopeptide 1 + 2, and D-dimers were not significantly modified by the use of heparin-coated ECC. Multivariate analysis showed that the intergroup differences in maximum C3b/c and C4b/c values were more pronounced in women in part with high baseline values of C3b/c. We also found that aprotinin contributed to the reduction of maximum values of fibrinopeptide 1 + 2 and D-dimers, whereas heparin coating had no significant influence on these parameters.

CONCLUSIONS

We found no evidence of combined properties of heparin-coated ECC and aprotinin in reducing complement activation, coagulation, and fibrinolysis. We therefore recommend use of both together to achieve maximal reduction of blood activation during cardiopulmonary bypass for coronary artery operations.

Clinical outcome after coronary surgery with heparin-coated extracorporeal circuits for cardiopulmonary bypass

In this prospective randomized trial, we studied whether heparin-coated extracorporeal circuits (ECC), known to reduce complement activation, could improve the clinical outcome of 200 patients undergoing coronary artery surgery. Patients have been divided into two groups (heparin-coated ECC and uncoated ECC groups) which were similar in terms of age, gender, left ventricle function, preoperative aspirin use and consequent intraoperative aprotinin use, number of grafts, duration of aortic cross-clamping and cardiopulmonary bypass. Univariate analysis showed that heparin coating did not reduce significantly postoperative bleeding (640 +/- 311 versus 682 +/- 342 ml with uncoated ECC) nor the need for transfusion (19% of patients versus 25% with uncoated ECC). Adverse events, including all mortality and morbidity noticed during the five first postoperative days, occurred in 20 patients of the uncoated ECC group and in eight patients of the heparin-coated ECC group (p = 0.013). The most frequent complications were supraventricular arrhythmias that occurred in 13 patients of the uncoated ECC group and in four patients of the heparin-coated ECC group (p = 0.02). Multivariate analysis by stepwise logistic regression showed that only heparin coating of the ECC was shown as a significant predictive factor of adverse events reduction (p = 0.01; odds ratio = 0.34). These data suggest that heparin coating reduced postoperative complications in patients undergoing coronary artery surgery.

Reduction of blood activation in patients receiving aprotinin during cardiopulmonary bypass for coronary artery surgery

Aprotinin reduces blood loss after cardiac surgery, particularly in patients taking aspirin. This study was performed to evaluate whether the reduction of contact phase activation by aprotinin is related to decreased complement activation during blood activation. Two hundred patients were prospectively operated on for coronary artery bypass. Aprotinin was used in the cardiopulmonary bypass (CPB) prime if aspirin was not discontinued 10 days before surgery and in patients undergoing second operation (n = 102). Blood loss was significantly reduced in patients receiving aprotinin (596 +/- 309 ml vs 754 +/- 329 ml without aprotinin; p = 0.0001), as was the need for transfusion (13% vs 34% without aprotinin; p = 0.0001) after surgery. Blood activation has been studied in 60 patients. Multivariate analysis showed that contact phase activation, as assessed by maximum values of C1 inhibitor/kallikrein complexes, was reduced by aprotinin treatment (p < 0.0001). Fibrinolytic activity decreased with aprotinin treatment, as reflected by lower values of D-dimers at the end of CPB (p < 0.0001). In addition, thrombin generation, as assessed by F1 + 2 scission peptide, was reduced by aprotinin (p = 0.01). However, the stepwise regression model emphasized that activation of the alternative and classic complement pathways, as reflected by C3b/c and C4b/c levels, was not affected by aprotinin; neither was leukocyte activation, as reflected by elastase release. These results suggest that aprotinin does not combine the reduction of complement activation with the reduced activation of the contact phase, fibrinolysis, or coagulation during CPB for coronary artery surgery.

Heparin-coated circuits and aprotinin prime for coronary artery bypass grafting

BACKGROUND

The biocompatibility of an extracorporeal circuit is improved by heparin bonding onto its inner surface. To determine the effect of heparin-coated circuits for cardiopulmonary bypass with aprotinin prime on postoperative recovery and resource utilization, a prospective study was done in 102 patients undergoing coronary artery bypass grafting with full systemic heparinization.

METHODS

Patients were randomly allocated to be treated with either a heparin-coated circuit (n = 51) or an uncoated circuit (n = 51). Differences in blood loss, need for blood transfusion, morbidity, and intensive care stay were analyzed.

RESULTS

No differences in blood loss and need for blood transfusion were found between the groups. The relative risk for adverse events in the heparin-coated group was 0.29 (95% confidence interval ranging from 0.10 to 0.80). Adverse events included myocardial infarction (2 patients in the uncoated group versus 0 in the heparin-coated group), rethoracotomy for excessive bleeding (1 versus 2), rhythm disturbance (7 versus 2), respiratory insufficiency (4 versus 0), and neurologic dysfunction (2 versus 0). The lower incidence of adverse events in the heparin-coated group was associated with a shorter intensive care stay (median, 2 days; range, 2 to 5 days) compared with the uncoated group (median, 3 days; range, 2 to 19 days, p = 0.03). The cost savings of 1 day of intensive care stay counterbalanced the additional costs of heparin-coated circuits.

CONCLUSIONS

The use of heparin-coated circuits for cardiopulmonary bypass with aprotinin prime resulted in a significant reduction in mobidity in the early postoperative phase and a concomitant decrease in intensive care stay, resulting in important cost savings.

The gastrointestinal tract: an underestimated organ as demonstrated in an experimental LVAD pig model

BACKGROUND

Although hemodynamic stability and renal function are important and are monitored closely in patients with implanted left ventricular assist devices (LVAD), the gastrointestinal tract may be underestimated in the early postoperative period with regard to adequate perfusion. We investigated renal, intestinal, and whole body metabolic changes in response to variations in LVAD flow and inspired oxygen concentration (FiO2).

METHODS

Left ventricular assist devices were implanted in 10 adult pigs (weight, 55 +/- 1.76 kg). Renal vein (RV), superior mesenteric vein (SMV), and pulmonary artery (PA) blood oxygen saturation and lactate concentration were measured and used as tissue perfusion markers. These measurements were made at baseline and after changes in LVAD flow or FiO2.

RESULTS

Oxygen saturation in the PA, SMV, and RV decreased significantly after a reduction in LVAD flow (P < 0.05), with a greater reduction in the SMV than in the PA and RV (p < 0.05 at LVAD flow 3.5L/min; p < 0.01 at LVAD flow 2.0 and 1.0 L/min). The lactate concentration in the PA and SMV increased significantly (p < 0.01) with decreased flow, with a greater increase in the SMV than in the PA (p< 0.05), whereas it remained unchanged in the RV. Oxygen saturation in the PA, SMV, and RV decreased significantly after a reduction in FiO2 (p < 0.05). Lactate concentration in the PA, SMV, and RV increased significantly at FiO2 of 0.10 (p < 0.05). Lactate concentration in the PA and SMV was significantly higher than that in the RV at Fi)2 of 0.10 (p < 0.01).

CONCLUSIONS

The results show that the gastrointestinal tract is at high risk during low perfusion or low FiO2, whereas the kidneys' metabolic function appears to be less disturbed. In clinical practice, this emphasizes the need to ensure adequate blood flow and respiratory function, especially after extubation, in patients with implanted LVAD. This might avoid intestinal ischemia and subsequent endotoxemia. Gastrointestinal tonometry may help in the assessment of intestinal perfusion.

[Orthotopic cardiac transplantation with caval anastomosis: a comparative randomized study with standard procedure in 81 cases]

Complete resection of the right atrium with conservation of a strip of left atrium around the 4 pulmonary veins followed by direct anastomosis on the vena cava has recently been proposed as an alternative to the standard orthotopic cardiac transplantation described by Shumway and Lower. In order to determine whether this "anatomical" transplantation should now be considered to be the procedure of choice, a prospective randomised study was undertaken in 1991 including 78 patients undergoing 81 cardiac transplantations by one of the two techniques: gr. I: classical transplantation (n = 40), gr. II: "anatomical" transplantation (n = 41). The groups were comparable in age, sex, weight, nature of the underlying cardiac disease and clinical status at the time of transplantation. Similarly, the parameters of the donors were comparable with respect to age, sex, weight and dosage of inotropic drugs at the time of explantation. All patients came of cardiopulmonary bypass with comparable ischaemia time of the graft (gr. I: 136 +/- 46 min; gr. II: 138 +/- 51 min). Immediate return to sinus rhythm occurred in 20 cases in gr. I and 36 cases in gr. II. Atrial arrhythmia persisted in 5 cases in gr. I but in no cases of gr. II. These differences were very significant (p < 0.001). There were 13 early deaths in gr. I and 8 in gr. II. Doppler echocardiography was performed two to three months after transplantation. The right atrial surface was significantly decreased in gr. II (18 +/- 4.7 cm2) compared with gr. I (24 +/- 7 cm2): the same difference was observed for the left atrium (gr. I: 24 +/- 4.5 cm2; gr. II: 20 +/- 5 cm2), p = 0.001. Tricuspid regurgitation was observed in 82% of patients in gr. I compared with 57% in gr. II (p < 0.005). Exercise stress tests during the same period showed no difference in peak oxygen consumption between the groups. Holter ECG monitoring led to permanent pacing in 2 patients of gr. I (5%). The technical simplicity and reduction of postoperative morbidity, especially with respect to arrhythmias, suggest an advantage with the "anatomical" technique considering the lack of surgical complications.

The superiority of hollow fiber membrane over bubble oxygenator in a perfusion circuit for the evaluation of small caliber endothelialized arterial prostheses

A perfusion circuit was constructed from a pneumatic ventricular assist device, 2 compliance chambers, 4 small-diameter silicone tubes (ID 4 mm) simulating shear inducing vascular prostheses, and an oxygenator with a heat exchanger. A bubble oxygenator (in a BO circuit) and a hollow fiber membrane oxygenator (in an MO circuit) were studied. The circuits were perfused with 30% human serum containing culture medium for 7 days at 37 degrees C. The pH, Po2, PCo2, Na+, K+, Ca2+, Cl, glucose, and total protein concentrations remained the same in BO and MO circuits during the 7 days of perfusion. The differences between the values measured in the perfusion medium and in the medium maintained in the static conditions of cell culture were not significant. In the BO circuit, the amount of cholesterol and triglyceride concentrations decreased whereas the relative amounts of albumin, alpha 1, alpha 2, beta, and gamma globulins remained stable in the perfusion medium. The medium from the BO circuit did not promote the proliferation of cultured human saphenous vein endothelial cells. In the medium from the MO circuit, the cholesterol and triglyceride concentrations did not change with perfusion time; the proliferation rate and anticoagulant function of endothelial cells were maintained. The hollow fiber membrane oxygenator preserves the biological characteristics of the cell culture medium in a perfusion circuit. The MO circuit permits the performance of relevant studies on shear stress resistance and functional activity of human endothelial cells seeded onto vascular prostheses.

Mechanical bridge to transplantation: when is too early? When is too late?

BACKGROUND

Optimal timing of implantation of a mechanical circulatory support system in the treatment of acute cardiogenic shock is still unsettled. The issue has been addressed in a retrospective analysis of a group of 98 patients in cardiogenic shock refractory to medical therapy who were candidates for cardiac transplantation, admitted from 1987 to 1994.

METHODS

The treatment included reinforced inotropic support by addition of phosphodiesterase inhibitors to sympathomimetic agents. The patients who did not improve were immediately brought to the operating room for mechanical circulatory support system implantation.

RESULTS

The overall survival in the group of 28 patients selected for mechanical bridge is 50%. No predictive factors of death or multiorgan failure while on the device could be identified, suggesting a lack of contraindications to mechanical circulatory support system implantation.

CONCLUSIONS

The high death rate in patients maintained on medical therapy because of initial improvement as they are awaiting transplantation suggests the benefit of a rapid semielective implantation of an intracorporeal device.

In vitro and in vivo evaluation of a small caliber vascular prosthesis fixed with a polyepoxy compound

A small caliber vascular prosthesis obtained from an ovine internal thoracic artery (3.8-4.5 mm ID) fixed with a polyepoxy compound and treated with heparin has been evaluated. Cytocompatibility was evaluated in vitro using human endothelial cells (HEC). HEC were obtained from human saphenous vein and cultivated in culture medium supplemented with 25% human serum. Graft segments were rinsed using a standard protocol proposed by the manufacturer. Tissue reaction was tested on a rabbit model of subcutaneous implantation. The patency rate and healing patterns were evaluated comparatively with polytetrafluorethylene (PTFE) 4 mm ID prosthesis in a canine model of carotid interposition. Cytocompatibility assay showed that there was low adhesion on vascular grafts (20 +/- 2% of endothelial cells seeded) and no growth of HEC on the graft surface. The graft patency rate was 55% in both groups, and actuarial freedom from occlusion was not different at 3 months (37.7 +/- 15% in Denacol-fixed grafts versus 38.1 +/- 14% in PTFE). Histological studies on the biological grafts shows a frequent neointimal hyperplasia at the anastomosis (5/12), a lack of endothelial cells lining the graft surface, a good preservation of the media, and a moderate inflammatory response in the adventicia. The Denacol-fixed graft has presented excellent surgical properties and preservation of the histological structure. Nevertheless, the patency rate was not improved when compared with the PTFE control graft.

Durability of the Mitroflow pericardial valve at ten years

From 1983 to 1992, 366 patients received 407 Mitroflow pericardial valves. Mean age was 62 +/- 14 years. Average follow-up was 72 +/- 28 months. Total follow-up was 1,791 patient-years. Overall survival in all patients was 77.2% +/- 2.2% at 5 years and 56.2% +/- 6.4% at 10 years. Freedom from structural valve deterioration was 95% +/- 1.2% and 36.7% +/- 8.1% at 5 and 10 years for all valves, 96.9% +/- 1.3% and 39.2% +/- 9.8% for aortic valve replacement, and 91.7% +/- 3.2% and 36.4% +/- 10% for mitral valve replacement (p = not significant). The freedom from structural valve deterioration in patients older than 70 years of age was 100% and 93.9% +/- 5.8% at 5 and 10 years, respectively. At 10 years, linearized rate of thromboembolism was 0.73% +/- 0.2% per patient-year and freedom from valve-related mortality for all valves was 88.8% +/- 2.8%. The best indication for the implantation of a Mitroflow valve is mitral or aortic disease in patients more than 70 years of age.

A right ventricular hemopump restores right ventricular function with pulmonary artery banding

We investigated the ability of the Hemopump to support the right ventricle during acute, partial, pulmonary artery obstruction. In 6 pigs, a 14 Fr size Hemopump was placed through the pulmonary artery into the right ventricle. Control measurements were made. A band around the pulmonary artery proximal to the outflow port of the Hemopump was tightened, and measurements were repeated with the Hemopump at minimum and then maximum speed. With banding, right ventricular stroke volume and output decreased (43 [SD, 7] to 28 [SD, 8] ml, p < 0.001; 4.9 [SD, 0.8] to 3.7 [SD, 1.0] L/min, p < 0.01 respectively), but they were restored with the Hemopump (38 [SD, 5] ml and 4.5 [SD, 0.6] L/min; both p = NS vs control). Increases in right ventricular peak systolic (28 [SD, 10] to 42 [SD, 17] mm Hg; p < 0.01) and end-diastolic pressure (2 [SD, 1] to 12 [SD, 6] mm Hg; p < 0.02) were reversed by the Hemopump (29 [SD, 8] and 4 [SD, 2] mm Hg; both p = NS vs control). Right ventricular pressure rate product almost doubled with banding (3,199 [SD, 1,252] to 5,962 [SD, 2,796] mm Hg; p < 0.01), but it decreased with the Hemopump (3,368 [SD, 767] mm Hg; p = NS vs control). With acute partial pulmonary artery banding, a right ventricular Hemopump restores output from and offloads the right ventricle.

The Mitroflow pericardial valve: clinical performance to 10 years

From 1983 to 1992, 366 patients received 407 Mitroflow pericardial bioprostheses at our institution. Mean age was 62 +/- 14 years (range: 15-86 years). There were 229 isolated aortic valve replacements (AVR), 96 isolated mitral valve replacements (MVR), 39 double mitral and aortic valve replacements (DVR) and four tricuspid replacements. Mean follow up was 6 +/- 2.33 years ranging from 1.67 to 10.9 years. Total follow up was 1791 patient-years. Overall survival was 77.2 +/- 2.2% at five and 56.2 +/- 6.4% at 10 years. It was 74 +/- 3% and 56.2 +/- 5.3% after AVR, 78.3 +/- 4.4% and 55.7 +/- 8.8% after MVR, 81 +/- 6.4% and 36.6 +/- 16.5% after DVR at five and 10 years, respectively. Freedom from structural valve deterioration (SVD) was 95 +/- 1.2% and 36.7 +/- 8.1% at five and 10 years for all valves, 96.9 +/- 1.3% and 39.2 +/- 9.8% for AVR, 91.7 +/- 3.2% and 36.4 +/- 10% for MVR. There was no difference in freedom from SVD between AVR and MVR. The freedom from SVD in patients older than 70 years of age was 100% and 93.9 +/- 5.8% at five and 10 years, respectively. Freedom from reoperation was 94.7 +/- 1.37% and 28.36 +/- 7.5% at five and 10 years for all valves, 96.2 +/- 1.5% and 38.6 +/- 9.7% for AVR, 91.7 +/- 3.2% and 36.4 +/- 10% for MVR. The denaturation process did not lead to acute hemodynamic deterioration. Pathologic findings were cuspal tears (one or more) associated with structural tissue changes.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo comparative study of two lactobionate based solutions for prolonged heart preservation

The duration of safe heart preservation must be improved. Using a heterotopic heart transplantation model, we compared in vivo the recovery of rabbits hearts preserved with a K+Lactobionate based fluid (UW: University of Wisconsin solution) or with a Na+Lactobionate based fluid. In the "preservation" group, hearts were cold stored (4 degrees C) for 6 hours with UW (n = 9) or Na+Lactobionate solution (n = 9). In the "transplantation" group, cold storage was followed by 3 hours of reperfusion (UW: n = 8, Na+Lactobionate solution: n = 7). Functional recovery, adenine nucleotide pool, circulating blood cardiac enzymes, circulating blood and tissue malondialdehyde (MDA) were measured. Left ventricular end-diastolic and developed pressures at different preload levels were better after preservation with UW than with Na+Lactobionate solution (p < 0.05). Also with UW, adenosine diphosphate and total adenine nucleotide content were significantly higher than with Na+Lactobionate solution (p < 0.05) whereas adenosine triphosphate, monophosphate and energy charges were similar. Cardiac enzymes and tissue MDA were similar with UW and Na+Lactobionate solution. In circulating blood, MDA was not detected. These results enhance the superiority of UW solution over a Na+Lactobionate based solution for long term heart preservation.

Orthotopic cardiac transplantation with direct caval anastomosis: is it the optimal procedure?

Total excision of the right atrium with a minimal cuff of left atrium remaining around the four pulmonary veins, followed by direct anastomoses on venae cavae, has been proposed as an alternative to the standard procedure described by Shumway and Lower for orthotopic cardiac transplantation. To investigate whether this "anatomic" transplantation should be proposed as the optimal procedure, we prospectively randomized 78 patients having 81 procedures since 1991 into two groups: group I, standard transplantation (n = 40), and group II, "anatomic" transplantation (n = 41). The two groups were statistically similar in recipient age, sex, weight, disease, and status at the time of transplantation. Also similar were donor age, sex, weight, and drug dependency at the time of harvesting. All patients could be weaned from cardiopulmonary bypass with comparable graft ischemic times (group I, 136 +/- 46 minutes; group II, 138 +/- 51 minutes). Immediate recovery of sinus rhythm occurred in 20 cases of group I and 36 cases of group II. Delayed recovery of sinus rhythm in the first postoperative week occurred in 15 cases of group I and 5 cases of group II. Persistence of atrial arrhythmia occurred in 5 cases of group I and never in group II. These differences were highly significant (p < 0.001). Postoperative hemodynamics showed a higher cardiac index at day 1 in group II (4.12 +/- 0.85 L/min per square meter) than in group I (3.77 +/- 0.65 L/min per square meter) (p = 0.04). There were 13 early deaths in group I and 8 early deaths in group II. One death in group I was related to an acute atrioventricular block at 3 weeks with no evidence of cardiac rejection at histologic examination. Two patients in group I (5%) required definitive pacemaker implantation for prolonged sinus node dysfunction. Echocardiographic and Doppler studies of survivors have been performed 2 to 3 months after transplantation. Right atrial area was significantly reduced (p < 0.01) in group II (18 +/- 4.7 cm2) versus group I (24 +/- 7 cm2), as was left atrial area (group I, 24 +/- 4.5 cm2; group II, 20 +/- 5 cm2) (p = 0.01). Mild tricuspid regurgitation was observed in 82% of group I patients versus 57% of group II patients (p < 0.05), inasmuch as mitral regurgitation was comparable (71% in group I, 67% in group II).(ABSTRACT TRUNCATED AT 400 WORDS)

Direct mechanical assistance of the right ventricle with the Hemopump in a porcine model

In 6 pigs, a 14F Hemopump was placed through the pulmonary artery into the right ventricle. The pulmonary artery was banded proximal to the outflow port of the Hemopump, and tightening the band increased right ventricular peak systolic pressure by 50%. There were significant falls in right ventricular stroke volume (from 43 +/- 7.3 mL [+/- the standard deviation] to 27 +/- 8.0 mL; p < 0.001) and cardiac output (from 4.94 +/- 0.76 L/min to 3.70 +/- 0.95 L/min; p < 0.01) and increases in right ventricular peak systolic pressure (from 28 +/- 9.7 mm Hg to 42 +/- 17.1 mm Hg; p < 0.01) and end-diastolic pressure (from 2 +/- 0.8 mm Hg to 12 +/- 6.4 mm Hg; p < 0.02). Mean aortic pressure fell (from 65 +/- 29.9 mm Hg to 61 +/- 9.6 mm Hg; p < 0.01), but systemic vascular resistance was unchanged, thus indicating a fall in left ventricular output reflected by a decrease in mixed venous oxygen saturation (from 60% +/- 8.9% to 47% +/- 7.6%; p < 0.01). After 15 minutes with the Hemopump at maximum speed, these variables returned to control levels (stroke volume, 38 +/- 4.5 mL; cardiac output, 4.50 +/- 0.63 L/min; right ventricular peak systolic pressure, 29 +/- 8.3 mm Hg; right ventricular end-diastolic pressure, 4 +/- 2.0 mm Hg; mean aortic pressure, 72 +/- 10.4 mm Hg; mixed venous oxygen saturation, 56% +/- 4.6% [all, p = not significant versus controls]).(ABSTRACT TRUNCATED AT 250 WORDS)

[Cardiac surgery in chronic hemodialysed patients: immediate and long-term results]

Between 1979 and 1993, 50 patients (33 men and 17 women) receiving chronic haemodialysis, underwent 53 cardiac surgical procedures in the department. The mean age was 56 +/- 13 years. The average duration of preoperative dialysis was 82 +/- 63 months. The average duration of cardiac symptoms before surgery was 35 +/- 52 months. Twenty-seven patients (54%) were in NYHA functional classes III or IV before surgery. Sixteen patients (32%) had preoperative left ventricular ejection fractions of less than 0.40. Twelve patients (24%) were emergency referrals. Twenty-nine patients underwent isolated coronary bypass surgery, 13 patients underwent isolated aortic valvular replacement which had to be repeated in one case, 3 patients underwent mitral valve replacement, which had to be repeated in 2 cases, and 5 patients underwent combined surgery. The average aortic clamping time was 75 +/- 32 minutes, the average cardio-pulmonary bypass time was 125 +/- 50 minutes. The surgical revascularisation of the coronary patients was incomplete in 37% of cases because of the severity of the underlying coronary artery disease. The average postoperative bleeding was 800 +/- 650 ml; 29 patients (58%) were transfused with an average of 4.3 +/- 3 units of blood. The global early mortality was 9 patients (18%); 10% in coronary bypass, 7% in aortic valve replacement and 50% in patients with more complex procedures. The causes of death were cardiac (n = 4), sepsis (n = 2) and multiple organ failure (n = 3). The morbidity was 39%, mainly due to low cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical implantation of the wearable Baxter Novacor ventricular assist system

Implantation of the wearable Novacor electrically powered left ventricular assist system was performed on March 16, 1993, in a 44-year-old man hospitalized for an acute episode of myocardial decompensation after a 6-year history of dilated cardiomyopathy. He was rehabilitated fully and became ambulatory, awaiting a suitable cardiac graft for 59 days. He is now back to work, enjoying a normal life. This case illustrates the progress made by miniaturization of the external components of the system. General acceptance of the system and psychological adaptation to the new way of life were remarkable.

Use of the Nippon-Zeon pneumatic ventricular assist device as a bridge to cardiac transplantation

The Nippon-Zeon (NZ) ventricular assist device is a sac type, air driven, heterotopic, external pump. Its performance has been evaluated in Japan as a bridge to myocardial recovery. Few data are available on the device as a bridge to heart transplantation. Since 1991, 10 patients (9 men) were bridged to heart transplantation with NZ, all in biventricular support. The mean age was 39 +/- 13 years (range, 21-60 years), mean body weight was 75 +/- 13 kg (range, 51-95 kg). Five patients had a dilated cardiopathy, and five were ischemic (three acute myocardial infarctions). Despite maximal inotropic support, including enoximone in seven, epinephrine in three, and intraaortic balloon pumping in one, eight patients were anuric, three were in acute hepatic failure, and three were intubated. Preoperative hemodynamic and biologic values were: cardiac index, 1.57 +/- 0.4 l/min/m2; pulmonary capillary wedge pressure, 34 +/- 5 mmHg; creatinine, 200 +/- 80 mumol/l; blood urea nitrogen, 17.5 +/- 8 mmol/l; total bilirubin 36 +/- 6 mumol/l; aspartate aminotransferase, 1,000 +/- 2,000 IU/l. In all patients, a biventricular assist device was implanted without the use of cardiopulmonary bypass. Improvement occurred immediately in all but one. Mean left ventricular flow was 4.5 +/- 0.8 l/min. Anticoagulation was maintained with intravenous heparin. Recently for bleeding was required in one case (10%), and two patients had positive blood cultures that were successfully treated. There was no mechanical failure. Hemolysis was not significant (lactate dehydrogenase, 378 +/- 50 IU/l; plasma-free hemoglobin below 10 mg/dl). Each device was free of thrombi and deposits at time of explantation. One patient died while on assist. Nine patients (90%) were transplanted after 11 +/- 8 days (range, 1-32 days). Three died early after transplantation, one of graft failure, two of sepsis. Six patients (66%) could be discharged. The follow-up ranges from 7 to 28 months. NZ is a simple, reliable, pneumatic device driven by a light, silent console; it can be rapidly implanted without cardiopulmonary bypass in patients in desperate condition who are awaiting cardiac transplantation. The difficulty of patient rehabilitation while using this device should limit the duration of support to weeks to allow the patient to be in optimal condition for heart transplantation.

Right heart function during left ventricular assistance in an open-chest porcine model of acute right heart failure

Changes in the right ventricular function measured with a thermodilution ejection fraction catheter have been recorded in open-chest normal pigs and pigs with acute right heart failure (RVF) undergoing left ventricular assistance with a pneumatic-sac-type device (LVAD). To produce acute right heart failure, 5 pigs underwent ligation of the right ventricular free wall coronary arteries. Compared with normal pigs, cardiac output in ligated pigs fell by 21% (7.5 +/- 0.5 vs 9.5 +/- 1.2 L/min; p < 0.05) and the right ventricular end diastolic pressure rose (11.4 +/- 2.6 vs 5.7 +/- 3.6 vs mmHg: p < 0.05). With the left ventricular assist device connected, the right atrial pressure was increased to 3, 5, 7, 10 and 12 mmHg by volume loading while maintaining the haematocrit at 35 +/- 6%. The right ventricular stroke work index (RVSWI) increased with volume loading in normal pigs. In RVF pigs, RVSWI increased significantly with the LVAD (59.2 +/- 5.8 vs 23.5 +/- 7.8 mmHg ml/min/kg, p < 0.01), approaching that of normal pigs (62.3 +/- 4.8 mmHg ml/min/kg). Similar changes were observed in the cardiac output and right ventricular stroke volume. These results show that, in this model of open-chest, mild, acute right heart failure, left ventricular assistance allows right ventricular function to return to normal, despite volume overloading, by decreasing right ventricular after load and increasing right ventricular compliance.

Donor/recipient aorta size mismatch in heart transplantation: a technical alternative

A technical alternative is proposed to enable transplantation in cases of considerable size mismatch between donor and recipient aorta: interposition of a Dacron graft of intermediate diameter. This procedure was performed in a 56-year-old patient weighing 75 kg in whom a heart from a 40-kg donor was implanted.

Mitroflow pericardial valve: long-term durability

Isolated aortic (n = 107), mitral (n = 63), and tricuspid (n = 1) valve replacement and 28 double-valve replacements were performed with a second generation of pericardial valves, the Mitroflow valve, in 199 patients from March 1983 to December 1986. Follow-up (total, 1,058 patient-years) was extended to 106 months and 91.5% complete. Mean age was 58 +/- 13 years. The operative mortality included 22 deaths, non-cardiac-related in 7. The actuarial probability of survival for all patients was 66% +/- 4% at 8.5 years. There were no significant differences between patients with aortic valve replacement, mitral valve replacement, or double-valve replacement. The rate of thromboembolic events, antithromboembolic therapy-related hemorrhage, periprosthetic leak, and endocarditis is extremely minimal. Structural valve dysfunction occurred at a rate of 3.2% +/- 0.5%/patient-year. Actuarial freedom from the event was 94.6% +/- 1.7% at 5 years and 63.7% +/- 6.5% at 8.5 years for all valves. There were no difference in structural valve dysfunction rate between patients having aortic, mitral, or double-valve replacement. Thirty-five patients were reoperated on (3.4 +/- 0.6%/patient-year for all). The rate of all valve-related morbidity and mortality was 5.6% +/- 0.7%/patient-year for all patients, actuarial freedom from the event being 44% +/- 7% at 8.5 years. These data suggest that the excellent hemodynamic characteristics of the valve are balanced by a risk of valve failure that is slightly increased when compared with porcine valves.

Preservation of the aortic valve in acute aortic dissection: long-term echocardiographic assessment and clinical outcome

The aim of the present study was to determine the long-term status of the native aortic valve after surgical treatment of acute aortic dissection involving the ascending aorta. From 1972 to 1991, 93 patients underwent operation for type I or II aortic dissection. There were 76 men and 17 women. Mean age was 54 +/- 13 years. Eighty patients (86%) had a conservative procedure regarding the aortic root and aortic cusps: 74 had prosthetic replacement of the ascending aorta and 6, complete replacement of the aortic arch. Thirteen patients (14%) had simultaneous replacement of the aortic valve and the ascending aorta. The overall hospital mortality rate was 29% (27/93). The overall actuarial survival rate was 60.2% +/- 5.2%, 49.7% +/- 6.1%, and 35.9% +/- 8.1% at 5, 10, and 15 years, respectively. The survival rates for patients who had an ascending aortic procedure only were 63% +/- 5.5%, 54% +/- 6.5%, and 39% +/- 8.5% at 5, 10, and 15 years, respectively, and for patients who required aortic valve replacement, 45% +/- 14% and 22% +/- 17.5% at 5 and 10 years, respectively. Fifty long-term survivors (94% follow-up) with preservation of the aortic valve and aortic root were studied. Among them, 9 (18%) died within a mean interval of 97 +/- 46 months after operation. Causes of death were ischemic cardiac failure (2), aortic rupture or extension of dissection (4), renal disease (1), stroke (1), and sudden death (1). Forty-one patients had long-term clinical and echocardiographic evaluation.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacological bridge to cardiac transplantation: current limitations

Addition of intravenous enoximone to sympathomimetic agents permits a rapid and drastic improvement in the clinical and hemodynamical condition of patients in cardiogenic shock referred for a mechanical bridge to transplantation. The present experience, based on the management of 52 patients, permits us to point out the current limitations of this pharmacological bridge: the rate of sudden death, the incompleteness of the physical rehabilitation of the patients, and the vanishing effect of intravenous enoximone.

Changes in hemodynamics and coronary blood flow during left ventricular assistance with the Hemopump

The Hemopump, a catheter-mounted left ventricular assist device, has been demonstrated to be effective in supporting patients with potentially reversible cardiac failure. The mechanism of recovery of the hearts with this device is not fully understood. The effects of the Hemopump on hemodynamics and coronary blood flow with and without myocardial ischemia and failure have been studied in 8 anesthetized open-chest dogs. Coronary blood flow in the left circumflex artery was assessed with an intracoronary Doppler catheter. Myocardial ischemia was induced by ligation of the left anterior descending and diagonal branches. The effects of maximum support were compared with those of minimum support. The effects of the Hemopump varied according to cardiac function. When cardiac dysfunction was mild, the Hemopump support slightly reduced myocardial O2 demand (assessed by pressure-work index) by volume unloading. When cardiac dysfunction was severe, total bypass was achieved and myocardial O2 demand decreased by 45%, owing to both volume and pressure unloading. Coronary blood flow was incompletely auto-regulated, and the ratio of blood flow to O2 demand increased.

Enhanced O2 transportation during cardiopulmonary bypass in piglets by the use of inositol hexaphosphate loaded red blood cells

A continuous lysing and resealing of erythrocytes permitted internalization of inositol hexaphosphate (IHP), a strong allosteric effector of Hb, leading to significant rightward shifts of the HbO2 dissociation curve. Twelve piglets were put on cardiopulmonary bypass (CPB) with the heart beating, cooled to 25 degrees C then rewarmed to 37 degrees C before weaning off CPB. AoP, LV pressure, PAP, and cardiac output (CO) were monitored. Blood samples were taken before CPB, at 25 degrees C, at 30 degrees C, at 37 degrees C and after CPB for assessment of blood gases, arterio-venous difference in O2 content, lactates, P50 (partial pressure of O2 at 50% Hb saturation), and ionogram. Control group I included five pigs where the CPB circuit was primed with Ringer's lactate solution and porcine blood. In group II (n = 5), priming was done with Ringer's lactate solution and IHP loaded erythrocytes. P50 was significantly higher during CPB than before surgery in group II (20%), but not in group I (1%). There was a significant increase in VO2 in group II (6.02 ml/min) compared to group I (4.03 ml/min) (p less than 0.05) after CPB. Hemodynamics improved after CPB in group II (mean AoP 42 mmHg and syst LVP 70 mmHg) compared to group I (AoP 25 mmHg and syst LVP 22.5 mmHg). These preliminary results show that O2 transportation at the end of CPB is enhanced and myocardial function is improved in piglets with the use of IHP erythrocytes.

Evaluation of direct effects of enoximone on systemic and pulmonary vascular bed in animals with a Jarvik total artificial heart

Enoximone, a phosphodiesterase inhibitor, has positive inotropic and vasodilating actions. To evaluate specific effects of this drug on the systemic and pulmonary vascular bed, we administered enoximone as a 10-minute intravenous bolus at two different doses of 2 and 3 mg/kg of body weight, at different days, to five Holstein calves with a Jarvik 7-70 ml total artificial heart (Symbion, Inc., Salt Lake City, Utah). The calves were monitored for aortic pressure, right atrial pressure, pulmonary arterial pressure, and left atrial pressure. For each experiment cardiac output was maintained constant, and systemic and pulmonary vascular resistances were calculated at 0, 15, 30, and 60 minutes and every hour for 8 hours after infusion. Statistical analysis used analysis of variance and the paired t test with Bonferroni's correction. Data showed the following: (1) a marked systemic vasodilating action of enoximone at peak effect at 30 minutes with a 20% decrease in systemic vascular resistance from baseline value under constant cardiac output, returning progressively to normal values throughout the 8 hours; (2) a comparable effect for the two separate doses tested; (3) no specific action on the pulmonary vascular bed with "nonunidirectional" changes in pulmonary vascular resistance. This model was validated by the infusion of prostaglandin I2 in the same animals, at different days, which significantly decreased pulmonary vascular resistance of 50% at peak effect, under constant cardiac output. In summary, enoximone showed a proper systemic vasodilating effect with no specific action on the pulmonary vascular bed in an animal model of the total artificial heart. Decrease in pulmonary vascular resistances obtained with enoximone in clinical practice seems more related to the inotropic properties of the drug. Enoximone should not be administered in pulmonary hypertension, as suggested before.

Endothelin dilates bovine pulmonary circulation and reverses hypoxic pulmonary vasoconstriction

To assess the effects of endothelin 1 (ET) on the pulmonary and systemic vascular beds simultaneously, we examined the hemodynamic responses to ET in awake calves implanted with a Jarvik total artificial heart (TAH), a device that maintains constant cardiac output (CO). During basal conditions, successive incremental intravenous (i.v.) injections of 1, 3, and 10 micrograms ET caused a dose-dependent decrease in pulmonary arterial pressure (PAP), (from 24 +/- 3 to 15 +/- 1 mm Hg, p less than 0.05) while having no effect on systemic arterial (SAP), left atrial (LAP), and right atrial (RAP) pressures. Administration of 30 micrograms ET i.v. also decreased PAP, had no effect on LAP and RAP, but increased SAP from 100 +/- 6 to 118 +/- 4 mm Hg (p less than 0.05). The decrease in PAP was rapid, occurring within seconds and lasting 10 min, whereas the increase in SAP occurred after 2-5 min and was prolonged for greater than or equal to 20 min. As compared with injection in the right atrium, administration of 30 micrograms ET into the left atrium reduced PAP to a similar extent, but induced a greater increase in SAP (+32.5 +/- 4 vs +17.5 +/- 2 mm Hg, p less than 0.05). ET also dose-dependently reversed the acute pulmonary vasoconstriction induced by inhalation of an hypoxic gas mixture. In all cases, pulmonary vasodilation occurred without evidence of short-term tolerance. The results demonstrate that ET is a potent in vivo pulmonary vasodilator. In calves, the predominant hemodynamic response to ET is pulmonary vasodilation, with systemic vasoconstriction apparent only at higher concentrations of the peptide.

Acute postinfarction septal rupture: long-term results

From 1973 to 1989, 66 patients received early surgical repair for acute postinfarction ventricular septal rupture. Mean age was 64 +/- 7 years (range, 45 to 80 years). Ventricular septal rupture occurred soon after acute myocardial infarction (3.4 +/- 4 days), and the first medical treatment occurred 6.7 +/- 7 days after onset of acute myocardial infarction. Three patients had a previous myocardial infarction. The site of the rupture was anterior in 38 patients (57%) and posterior in 28 (43%). Forty-four patients (67%) were in shock at the time of admission. Intraaortic balloon pumping was used preoperatively in 28. Operation was performed at the time of maximal efficacy of medical treatment. The same technique was used in all cases. Associated procedures included coronary bypass grafting in 5 patients and valvar operation in 5. The patients have been carefully followed up for up to 16 years. Hospital mortality was 45% (30 patients) and was cardiac related or due to acute renal failure in 25 patients (83%). No correlation could be revealed between early death and age, sex, preoperative intraaortic balloon pumping, or year of operation. Location of the ventricular septal rupture (early mortality of 57% for posterior versus 37% for anterior ventricular septal rupture) and shock at the time of admission (52% versus 32%) showed a trend toward significance (0.08 less than or equal to p less than 0.10). Response to initial active therapy has a strong predictive value (mortality of 70% in unresponsive patients versus 14% in responders; p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Hemopump support on left ventricular unloading and coronary blood flow

The effects of the Hemopump (HP) on left ventricular (LV) and coronary hemodynamics, with and without myocardial ischemia, were studied in an acute, anesthetized, open-chest dog preparation (n = 6). Coronary blood flow velocity in the left circumflex was assessed with an intracoronary Doppler catheter. Measurements were made at two pump speeds (minimal = HP1 and maximal = HP7) before coronary ligation (control), after ligation of the LAD (ischemia), and after induction of cardiac failure by multiple ligations of the diagonal branches (failure). Changing from HP1 to HP7 resulted in 1) Increased total cardiac output in ischemia and failure; 2) Increased mean aortic pressure and systemic vascular resistance in control, ischemia, and failure; 3) Decreased LV external work (LV systolic pressure X stroke volume) in control, ischemia, and failure; 4) Decreased LV end diastolic pressure in ischemia; 5) Decreased LV systolic pressure and pressure-rate product in failure; and 6) Increased coronary blood flow/O2 demand ratio in failure. Hemopump support reduced O2 demand by LV decompression, and improved blood flow/O2 demand ratio in the nonoccluded coronaries of ischemic, failing hearts.

Intraoperative transesophageal echocardiography for pulmonary embolectomy without cardiopulmonary bypass

This case report describes a patient with massive pulmonary embolism and acute circulatory failure in whom transesophageal echocardiography permitted the diagnosis of thrombi in the main pulmonary truncus and in the right branch and guided intraoperatively the surgical embolectomy performed under simple venous inflow occlusion because of a contraindication to heparin administration. Transesophageal echocardiography seems to be a very helpful technique to diagnose promptly massive pulmonary embolism and a very useful tool at the time of operation to guide the embolectomy.