Reduction of gaseous microembolism during aortic valve replacement using a dynamic bubble trap

Serious postoperative psycho-neurological dysfunction is at least partially attributed to the occurrence of gaseous microbubbles in the arterial line of extracorporeal circulation (ECC). Therefore, we investigated in a prospective randomized double blind study whether the usage of dynamic bubble trap (DBT) will reduce microbubble load of patients undergoing aortic valve replacement. Patients (n = 41) were divided into group I (GI, n = 22) with DBT introduced into the arterial line of ECC and group II (GII, n = 19) with placebo-DBT instead. Doppler ultrasonography was used for detection of microbubbles before and after DBT, and for detection of high intensity transient signals (HITS) within the middle cerebral artery. The recording time during ECC was divided into period 1 (P1, until aortic clamp removal) and period 2 (P2, clamp removal until the end of ECC). A significant reduction of microbubble load was found in GI only (p < 0.0001 for ECC; p < 0.0001 for P1; p < 0.0025 for P2). A significant difference in number of HITS between the groups was observed in P1 only (p < 0.002 left middle cerebral artery, p < 0.005 right middle cerebral artery), since in P2 the trapped air in left chamber can go to the supraaortal vessels without passing ECC. In conclusion the use of DBT cannot substitute careful venting after aortic declamping. Nevertheless, reduction of HITS in the cross-clamped period of ECC justifies the use of DBT in patients undergoing open chamber surgery.

Non-Aneurysmal Inflammation of the Aorta in Combination with Aortic Valve Disease

A 61-year-old man presented with aortic valve stenosis, coronary artery disease in combination with rheumatic arthritis, peri-aortic inflammation and fibrosis with aortitis. In the pathological literature this has been termed chronic periaortitis, while in the surgical literature, non-aneurysmal dilatation of the aorta associated with atherosclerosis and inflammation has been described as aortitis. The name chronic periarteritis refers to the associated involvement of coronary arteries. Although different terminologies have been used, it is suggested that all of them most likely represent the same disease entity.

Leukocyte-depleted Secondary Blood Cardioplegia Attenuates Reperfusion Injury after Myocardial Ischemia

BACKGROUND

Activated neutrophils have been implicated in reperfusion injury of the myocardium; leukocyte depletion at the time of reperfusion may contribute to better myocardial protection after cardiac surgery. In the present study, we examined whether leukocyte depletion as an adjunct to terminal blood cardioplegia attenuates reperfusion injury.

METHODS

Porcine hearts that had undergone 60 minutes of normothermic ischemia with cardioplegia and 60 minutes of reperfusion under cardiopulmonary bypass were divided into four groups according to the methods of 15 min of controlled initial reperfusion: whole blood reperfusion (n = 6), leukocyte-depleted reperfusion (n = 6), secondary blood cardioplegia (n = 6) and leukocyte-depleted secondary blood cardioplegia (n = 6). At 60 min of reperfusion, hemodynamic recovery, release of malondialdehyde (MDA) as a marker for free oxygen radicals, CK-MB-isoenzyme from the coronary sinus, recovery of adenosine triphosphate, and myocardial water content were evaluated.

RESULTS

The group with leukocyte-depleted secondary blood cardioplegia showed the best hemodynamic recovery (Emax and total dp/dt), lowest levels of MDA, CK-MB and myocardial water content, and highest adenosine triphosphate recovery.

CONCLUSIONS

These results suggest that controlled reperfusion with leukocyte-depleted secondary blood cardioplegia attenuated severe damage of the myocardium as compared to whole blood reperfusion.

INR self-management permits lower anticoagulation levels after mechanical heart valve replacement

BACKGROUND

The Early Self Controlled Anticoagulation Trial (ESCAT I) showed that anticoagulation self-management after mechanical heart valve replacement decreased complication rates by maintaining INR levels closer to the target range than International Normalized Ratio (INR) home doctor management. The therapeutic range for the INR in that study was between 2.5 and 4.5 for all positions of prosthetic valves. ESCAT II should find out whether lowering the target range for INR self-management would further reduce complication rates.

METHODS

ESCAT II is a prospective controlled randomized (valves: St. Jude Medical Standard or Medtronic Hall, treatment: conventional/low-dose) multicenter study with 3,300 patients. We present interim results of 1,818 patients. 908 were categorized as having a low-dose target range, which was INR 1.8 to 2.8 for prostheses in aortic position and 2.5 to 3.5 for prostheses in mitral position or in combined valve replacement. The control group (conventional group) with 910 patients aimed at an INR of 2.5 to 4.5 for all valve positions.

RESULTS

In the conventional group, 74% of INR values measured were within the therapeutic range. In the low-dose group, 72% of the values were within that range. The linearized thromboembolism rate (% per patient year) was 0.21% for both groups. The bleeding complication rate was 0.56% in the low-dose regimen group versus 0.91% in the conventional group.

CONCLUSIONS

Early onset INR self-management under oral anticoagulation after mechanical heart valve replacement enables patients to keep within a lower and smaller INR target range. The reduced anticoagulation level resulted in fewer grade III bleeding complications without increasing thromboembolic event rates.

Predictors for atrial transport function after mini-maze operation

BACKGROUND

Restoration of atrial transport function (ATF) is a major goal of the maze procedure. This prospective study was undertaken to evaluate predictors of left atrial transport function in patients undergoing a mini-variant of the maze III procedure 3 and 12 months postoperatively.

METHODS

Mini-maze operation was performed in 72 patients with a mean age of 64 +/- 8.7 years during a 5-year period. Seventy of 72 (97%) had combined procedures. Clinical and electrophysiologic examination was carried out before surgery, and 3 and 12 months postoperatively.

RESULTS

Early mortality was 1.4% (1 of 72 patients) and late death occurred in 5.6% (4 of 71 patients). After 3 months, 54 of 68 (80%) patients showed sinus rhythm, and 48 of 60 (80%) after 12 months. ATF was restored in 87% (echocardiography) and 82% (magnetic resonance imaging) after 3 months, and in 86% (echocardiography) and 78% (magnetic resonance imaging) after 12 months. Independent predictors for ATF restoration after 12 months were better preoperative left ventricular function (p = 0.02), and smaller preoperative left atrial diameter (p = 0.005). Correlation between echocardiography and magnetic resonance imaging was 80% after 12 months.

CONCLUSIONS

Restoration of ATF after mini-maze procedure is achieved in over 80%. Independent predictors for ATF restoration are smaller preoperative left atrial diameter and better preoperative left ventricular ejection fraction.

Ruptured papillary muscle after mitral valve replacement with preservation of chordae tendineae

Many cardiac surgeons believe strongly that every effort should be made to preserve the continuity of the mitral anulus, chordae tendineae, and papillary muscles during mitral valve replacement in order to maximize ventricular function and maintain normal ventricular geometry. We treated a patient with spontaneous papillary muscle rupture after mitral valve replacement in whom efforts had been made to preserve continuity of the mitral mechanism.

Symptomatic aneurysm of a saphenous vein graft with compression of the right atrium

A symptomatic aneurysm of a saphenous vein bypass to the right coronary artery in a 77-year-old female patient is presented. Surgical therapy included resection of the aneurysmal saphenous vein graft, reconstruction of the right atrium, and coronary artery bypass grafting (CABG) to the right coronary artery.

[Papillary muscle rupture after mitral valve replacement with preservation of subvalvular structures]

We report a female patient with mitral valve replacement and preservation of subvalvular apparatus in which parts of the papillary muscle ruptured postoperatively. During systole the ruptured papillary muscle prolapsed through the native aortic valve. Echocardiographic documentation and operative procedure were demonstrated.

Peripheral arterial embolism originating from a thrombus in the ascending aorta

A 45-year-old man experienced arterial thromboembolism to the right leg requiring surgical restoration of blood flow. Transesophageal echocardiography (TEE) was performed to determine the source of embolism and identified a localized atherosclerotic lesion in the distal ascending aorta with an adherent, highly mobile thrombus. The patient underwent surgery with removal of the atherosclerotic plaque and attached thrombus, and resection of the adjacent aortic wall. This case illustrates an unusual location for a complex atherosclerotic lesion in the ascending aorta, and points out the opportunity for remedial surgery once a symptomatic embolus has occurred.

[The maze operation--surgical therapy of chronic atrial fibrillation: modification to mini-maze operation]

OBJECTIVE

Atrial fibrillation (AF) is the most common arrhythmia. However, its precise electrophysiologic mechanism is still not well understood. Chronic symptomatic atrial fibrillation resistant to medical therapy can successfully be treated by the Maze III procedure (M III). Several publications are dealing with alternative surgical techniques. This study describes technique and midterm results of a Mini-variant (Mini) of the Maze III procedure.

METHODS

During a 48-month period we performed either a M III (group I = 7 patients) or a Mini-Maze operation (group II = 65 patients) in 33 males and 39 females with chronic symptomatic atrial fibrillation and additional cardiac pathology. Patients were controlled 4.0 +/- 1.8 months (group I) respectively 3.6 +/- 0.8 months (group II) (NS) and 16.75 +/- 2.5 months (group I) respectively 13.2 +/- 1.9 months (group II) (NS) after operation by means of thorough electrophysiological assessment, right heart catheterization, MRI, echocardiography, stress-ECG and 24 h-ECG.

RESULTS

There was no significant difference between the two groups with regard to sex, age and duration of AF. Echocardiographic left atrial diameter (LAD) was 75 +/- 11 mm in group I and 65 +/- 8 mm in group II (p = 0.002). Whereas right atrial diameter was 62 +/- 8 mm in group I and 57 +/- 7 mm in group II (NS). Perioperative data (n = 72): Aortic cross clamp time was 127 +/- 40 min in group I and 87 +/- 22 min in group II (p = 0.0002). Cardiopulmonary bypass time was 185 +/- 71 min in group I and 137 +/- 42 min in group II (p = 0.01). Postoperative data I (first follow-up: n = 66): sinus rhythm (yes): 4/7 vs. 47/59 (NS); pacemaker (PM) in AAI mode (yes): 1/7 vs. 3/59 (NS); inducible atrial fibrillation (yes): 2/7 vs. 5/59 (NS); Bradycardie Tachycardie Syndrome with the need of PM implantation 0/7 vs. 4/59 (NS). Postoperative data II (second follow-up: n = 55): sinus rhythm (yes): 5/7 vs. 34/48 (NS); PM in AAI mode (yes): 0/7 vs. 4/48 (NS); Inducible atrial fibrillation (yes): 2/7 vs. 5/48 (NS); Bradycardia Tachycardia Syndrome with the need of PM Implantation 0/7 vs. 5/48.

CONCLUSION

Midterm results are identical after M III and Mini. The Mini-Maze procedure is less complex compared to the Maze III procedure and there is a significant reduction of crossclamp and ECC times. We recommend the Mini especially for polymorbid patients and for those with poor left ventricular function.

Significant reduction of air microbubbles with the dynamic bubble trap during cardiopulmonary bypass

Air microbubbles mostly occur unnoticed during cardiopulmonary bypass and are predominantly responsible for serious postoperative psychoneurological dysfunction. A dynamic bubble trap (DBT), which removes air microbubbles from the arterial blood, was tested in a clinical study. The aim was to evaluate the efficiency of microbubble removal under clinical conditions. As blood passes through the DBT, which is placed in the arterial line between the arterial filter and arterial cannula, it is converted into a rotating stream. The bubbles are directed to the centre of the blood flow and are collected in the distal end of the DBT, from where they are returned to the cardiotomy reservoir. Doppler ultrasonography was used to detect the microbubbles before and after the DBT, and also the number of high-intensity transient signals (HITS) in the right and left middle cerebral artery during extracorporeal circulation. A significant reduction of microbubbles in the arterial line (3,990 before DBT, 537 after, p < 0.001) and HITS in the brain (51 in the DBT group, 77 in the placebo group, p = 0.04) was measured.

A self-perpetuating vicious cycle of tissue damage in human hibernating myocardium

Recently, we proposed the hypothesis that a vicious cycle exists in human hibernating myocardium (HM) between the progression of myocyte degeneration and the development of fibrosis. We now investigated the pathomechanism of this cycle in more detail and established a correlation between the severity of the morphological changes and the degree of postoperative functional recovery of HM. HM was diagnosed by dobutamine echocardiography, thallium-201 scintigraphy and radionuclide ventriculography. Functional recovery was present at 3 months after coronary bypass surgery but remained unchanged at 15 months. Forty patients were subdivided into 2 groups: A with complete and B with incomplete recovery. Biopsies taken during surgery and studied by electron microscopy, immunocytochemistry, rt-PCR, and morphometry revealed myocyte degeneration and inflammatory and fibrinogenic changes in a widened interstitial space. We report here for the first time an upregulation of TGF-beta1 evident by a 5-fold increase of fibroblasts and macrophages exhibiting a TGF-beta1 content 3-fold larger than in control, and a > 3-fold increase in TGF-beta1 mRNAby rt-PCR. The number of angiotensin converting enzyme (ACE) containing structures was increased (n/mrm2: control-11.4, A-17.6, B-19.2, control vs. A and B, p < 0.05). Fibrosis was more severe in group B than A or control (%: C-10.1; A-21.2; B-40.6; p < 0.05). Capillary density was significantly reduced (n/mm2: C-1152; A-782; B-579, p < 0.05) and intercapillary distance was widened (microm: C-29.5, A-36.1, B-43.3, p < 0.05). The number of CD 3 (n/mm2: C-5.0; A-9.6; B-9.4, ns) and CD 68 positive cells (n/mm2: C-37.2; A-80.7; B-55.0, C vs. A p < 0.05) was elevated in HM as compared to control indicating an inflammatory reaction. Cut-off points for functional recovery are fibrosis > 32%, capillary density < 660/mm2 and intercapillary distance > 39.0 microm. In HM a self-perpetuating vicious cycle of tissue alterations leads to progressive replacement fibrosis and continuous intracellular degeneration which should be interrupted by early revascularization.

The effect of leukocyte-depleted blood cardioplegia in patients with severe left ventricular dysfunction: a randomized, double-blind study

BACKGROUND

The propensity for leukocytes to cause reperfusion injury in patients undergoing heart surgery is widely accepted. Reperfusion injury may result in myocardial damage and unfavorable operative outcome, especially in patients with severely reduced ejection fractions. This study was performed to evaluate the impact of leukocyte filtration on the postoperative course of patients undergoing coronary bypass surgery.

METHODS

Thirty-two patients with coronary artery disease and left ventricular ejection fraction less than 35% were included in this double-blind, randomized study. Two serial leukocyte removal filters (Pall BC1B filter [Pall Biomedical, Portsmouth, England], group F, 15 patients) or two dummy filters (group C, 17 patients) were connected to the blood cardioplegia line. Leukocyte count, hemodynamic measurement, and transesophageal echocardiography were performed before and after cardiopulmonary bypass. Cardiac-specific enzymes were analyzed from arterial blood during the first 72 hours and from coronary sinus blood 30 and 60 minutes after aortic unclamping.

RESULTS

Patient characteristics were similar in the two groups (ejection fraction 20.9% +/- 4.3% in group C and 21.1% +/- 4.8% in group F; P =.773). No early death or perioperative myocardial infarction occurred. Leukocyte count, hemodynamic parameters, cardiac troponin T, cardiac troponin I, and creatine kinase MB mass levels in arterial blood were similar in the two groups. Group F showed lower release of cardiac troponin T from the coronary sinus 30 minutes after unclamping of the aorta (group F, 0.263 +/- 0.12 ng/mL; group C, 0.6 +/- 0.32 ng/mL; P =.005). Lower doses of dopamine were necessary after cardiopulmonary bypass (group F, 0.36 +/- 0.11 mg x kg(-1) x min(-1); group C, 0.49 +/- 0.14 mg x kg(-1) x min(-1); P =.003). A moderate increase in ejection fraction was observed at 30 minutes in both groups (group F, 30.3% +/- 6.2%; group C, 28.0% +/- 6.3%; P =.239) and a significant increase at 60 minutes in group F (group F, 32.5% +/- 6.0%; group C, 27.4% +/- 7.5%; P =.012).

CONCLUSIONS

These results indicate that serial leukocyte filters connected to the blood cardioplegia line decrease myocardial cell injury and may therefore help to improve outcome of patients with severely depressed ejection fractions undergoing coronary artery bypass grafting.

A dynamic bubble trap reduces microbubbles during cardiopulmonary bypass: a case study

Microemboli passing to the cerebral circulation during cardiopulmonary bypass can contribute to postoperative neurologic dysfunction. Many studies conclude that air microbubbles predominantly are responsible for this problem. A dynamic bubble trap (DBT) was developed to diminish the number of microbubbles in the arterial line of extracorporeal circulation. The DBT is able to substantially reduce the number of air microbubbles, as shown in two patients undergoing coronary artery bypass grafting, where a high number of microbubbles was assessed. Although a 40-micron arterial filter was used, many bubbles larger than 40 microns occurred in the arterial line. The DBT reduced the number of large microbubbles from 2,267 to 67 in patient 1 and from 897 to 61 in patient 2.

[Symptomatic true aneurysm of a venous bypass with compression of the right atrium]

A symptomatic true aneurysm of a saphenous vein graft to the right coronary artery in a female patient twelve years after bypass surgery is presented. Beating heart surgery included resection of the aneurysmatic saphenous vein graft, reconstruction of the right atrium and coronary artery bypass grafting to the right coronary artery. The symptoms of aneurysms of vein grafts, the diagnostic procedures and the surgical treatment are discussed.

Increased expression of cytoskeletal, linkage, and extracellular proteins in failing human myocardium

Experimental studies have shown that in hypertrophy and heart failure, accumulation of microtubules occurs that impedes sarcomere motion and contributes to decreased ventricular compliance. We tested the hypothesis that these changes are present in the failing human heart and that an entire complex of structural components, including cytoskeletal, linkage, and extracellular proteins, are involved in causing functional deterioration. In explanted human hearts failing because of dilated cardiomyopathy (ejection fraction </=20%), expression of alpha- and beta-tubulin, desmin, vinculin, fibronectin, and vimentin was determined by Northern and Western blot analysis and compared with normal myocardium from explants not used for transplantation. The mRNA for alpha- and beta-tubulin was increased to 2.4-fold (P<0.01) and 1.25-fold (NS), respectively; for desmin, 1.2-fold (P<0.05); for fibronectin, 5-fold (P<0.001); and for vimentin, 1.7-fold (P<0.05). Protein levels for alpha-tubulin increased 2.6-fold (P<0.02); for beta-tubulin, 1.2-fold (P<0.005); for desmin, 2.1-fold (P<0.001); for vinculin, 1.2-fold (P<0.005); for fibronectin, 2.9-fold (P<0.001); and for vimentin, 1.5-fold (P<0. 005). Confocal microscopy showed augmentation and disorganization of all proteins studied. In combination with the loss of myofilaments and sarcomeric skeleton previously reported, these changes suggest cardiomyocyte remodeling. Increased fibronectin and elevated interstitial cellularity (vimentin labeling) indicate progressive fibrosis. The present results suggest a causative role of cytoskeletal abnormalities and myofilament loss for intrinsic contractile and diastolic dysfunction in failing hearts.

Midterm results after the Mini-Maze procedure

OBJECTIVE

Atrial fibrillation (AF) is the most common arrhythmia. However, its precise electrophysiologic mechanism is still not well understood. Chronic symptomatic AF resistant to medical therapy, can successfully be treated by the Maze III procedure (M III). However, there are several publications dealing with alternative surgical techniques. This study describes technique and midterm results of a Mini-variant of the M III procedure.

METHODS

During a 38-month period we performed either an M III (seven patients) (group I) or a MINI-operation (45 patients) (group II) with chronic symptomatic AF and additional cardiac pathology. Patients were controlled 3.6 +/- 0.9 and 14.9 +/- 2.2 months after operation by means of thorough electrophysiological assessment, right heart catheterization, magnetic resonance imaging (MRI), echocardiography, stress-EGG and 24-h-ECG.

RESULTS

There was no significant differences between the two groups with regard to sex, age and duration of AF. Echocardiographic left atrial diameter (LAD) was 75 +/- 11 mm in group I and 67 +/- 8 mm in group II (P = 0.01). Whereas right atrial diameter was 62 +/- 8 mm in group I and 56 +/- 7 mm in group II (NS). Perioperative data (n = 52): aortic cross clamp time was 127 +/- 40 mm in group I and 87 +/- 21 mm in group II, (P = 0.0002). Cardiopulmonary bypass time was 185 +/- 71 mm in group I and 137 +/- 46 mm in group II, (P = 0.02). Postoperative data: there was no difference between the two groups with regard to sinus rhythm, prolonged sinus node recovery time, pacemaker (PM) in AAI-mode, inducible atrial fibrillation, reduction of left and right atrial size after a follow-up interval of 3.6 months and 1 year, respectively.

CONCLUSION

Midterm results are identical after M III and MINI. MINI is less complex compared to the M III procedure and there is a significant reduction of crossclamp- and ECC-time. We recommend the MINI especially for polymorbid patients, and for those with poor left ventricular function.

Transmyocardial laser revascularisation has no beneficial effect on high energy phosphates and lactate content during acute myocardial ischaemia in pigs

OBJECTIVE

Transmyocardial laser revascularisation (TMLR) is used to treat endstage coronary heart disease. There is evidence that angina is significantly reduced after TMLR. However, the precise mechanism by which symptoms disappear remains unknown. The objective of the present study was to examine the potential effects of TMLR on high-energy phosphates and myocardial perfusion in an acute ischaemic model.

METHOD

Five male landrace pigs (42 +/- 1.8 kg) had TMLR of the anterolateral wall of the left ventricle using a 1000 W CO2 laser (PLC, USA). Thereafter the anterior descending coronary artery was occluded with a tourniquet. After 90 min of ischaemia, drill-biopsies were taken from ischaemic and non-ischaemic areas as well as from laser channels. The specimens were snap-frozen in liquid nitrogen. Subsequently, methylene blue was injected into the left atrium to study tissue distribution. The hearts were excised and the patency of channels was examined visually.

RESULTS

Coronary artery occlusion resulted in immediate blue discoloration in both TMLR and control areas. There was no subendocardial methylene blue staining around laser channels. Inspection of hearts showed occlusion of laser channels due to thrombus formation at both endo- and epicardial levels. ATP-metabolites significantly increased in ischaemic areas compared to non-ischaemic areas. Furthermore there was significant upregulation of purine-content in ischaemic regions even in areas with laser channels.

CONCLUSIONS

In our acute model there was early occlusion of the channels after TMLR. We suggest that clinical improvement after this procedure is not due to increased myocardial oxygen delivery, since high energy phosphate levels and lactate content remained unchanged.

Cardioscopy: potential applications and benefit in cardiac surgery

OBJECTIVE

Cardioscopy in open heart surgery is still not routine in most units. However, since our first report in 1996 we use this device more frequently, because we think that safety and accuracy of different surgical procedures is increased.

METHODS

Between 1/96 and 12/97 we performed cardioscopy in 100 patients. Indications (IND) for cardioscopy were as follows: IND (1) resection of hypertrophied septum (N = 15); IND (2) evaluation of aortic valve with low grade stenosis or insufficiency (N = 12); IND (3) removal of intracardiac foreign bodies/tumors (N = 13); IND (4) inspection of VSD prior and after repair (N = 8); IND (5) identification of paravalvular leakage (N = 8); IND (6) diagnostic purposes (N = 4); IND (7) education of surgeons and operating room staff (N = 40). During cardioplegic arrest the 5 mm rigid or flexible cardioscope (Storz, Tuttlingen, Germany) was inserted through ascending aorta, aortic valve or tricuspid valve depending on indication.

RESULTS

No complication occurred during cardioscopy. IND (1): there was an excellent view of all intracardiac structures. Thorough resection of hypertrophied septum was possible and there was no injury of adjacent structures or aortic valve. IND (2): all valves were inspected through a 1 cm aortic incision and the pathology of the valves was documented. In case of severe calcification, the valve was replaced although transvalvular gradient was less than 50 mm Hg. IND (3): intraventricular foreign bodies, such as felt pledges (N = 2), debris (N = 5), thrombi (N = 4) and tumors (N = 2) were entirely removed through the aortic valve with a special forceps. IND (4): anatomy of VSD was documented in all cases. It was possible to test accuracy of all patch-sutures. IND (5): all paravalvular leakages were identified even though there was heavy immobility of the mechanical valve. IND (6): a papillary muscle (N = 2) and a thrombus formation (N = 2) were diagnosed. IND (7): the surgeons and operating room staff could follow the entire procedure in all cases.

CONCLUSIONS

Cardioscopy is a supporting technique to clearly identify intracardiac structures, to control several surgical procedures, to document valve pathology, and to educate surgeons and operating room staff. Handling is easy and does not increase operative risk. Some procedures will be performed with minimal invasivity in future.

Repair of an aneurysm of the pulmonary trunk in a 65-year-old patient

The case of a 65-year-old patient with asymptomaticaneurysm of the pulmonary trunk associated with severe insufficiency of the pulmonary valve and symptomatic coronary artery disease is presented. The surgical procedure included coronary artery bypass grafting, aneurysmectomy, and pulmonary artery replacement with implantation of a stentless bioprosthesis and lengthening of the root of the bioprosthesis with a reversed vascular Y prosthesis, which was anastomosed to the left and right pulmonary artery.

The extracellular matrix in hibernating myocardium--a significant factor causing structural defects and cardiac dysfunction

Recently, we described chronic intracellular degeneration accompanied by fibrosis as typical structural features of hibernating myocardium and we concluded that cellular degeneration as a sign of the incomplete adaptation to the reduced blood flow is characteristic of hibernation. This study has been extended by analyzing the composition of the extracellular matrix proteins of the diseased myocardium. Areas of hibernating myocardium were identified in 38 patients by angiography, multigated radionuclide ventriculography, thallium scintigraphy with reinjection and low-dose dobutamine echocardiography. These areas were biopsied at cardiac surgery and were studied by electron microscopic and immunofluorescence techniques. Electron microscopy showed an enlarged extracellular space containing numerous particles of cellular debris, macrophages, fibroblasts, homogeneous matrix material and collagen fibrils. The basement membrane of the cardiomyocytes was thickened by an augmentation of laminin, fibronectin and collagen VI, but these proteins also were present in the matrix itself. Collagen fibrils were numerous and macrophages (CD68) and fibroblasts (vimentin) were increased. In situ hybridization showed an increase in mRNA for laminin, fibronectin and collagen. This observation is consistent with the conclusion that fibrotic scar formation was occurring continuously. It is postulated that fibrosis is the consequence of myocyte loss due to chronic underperfusion in the hibernating tissue. This will further injure myocytes so that a vicious cycle is established that leads to progressive loss of structural integrity and functional capacity. Since these changes are progressive, revascularization should be performed at the earliest time point possible in patients with areas of hibernating myocardium.

[Dysfunctions of transvenous cardioverter/defibrillator electrode systems: clinical significance of system integrated diagnosis and measurement function--possibilities of partially automated system control]

The aim of this study is the analysis of electrical failures in transvenous cardioverter/defibrillator (ICD) lead systems with regard to the importance of device implemented diagnostic and measurement functions and the potential role of an automated device-control in the detection of lead failures.

METHODS

All consecutive ICD patients at our institution were enrolled in this retrospective investigation. The routine follow-up controls consisted in a complete evaluation of all diagnostic and measurement ICD features and additional controls in case of spontaneous arrhythmia episodes.

RESULTS

Two hundred thirty patients, 193 male and 37 female, were enrolled in this study (mean age: 61.5 +/- 10.2 years; mean LVEF 32 +/- 9%). During a mean follow-up period of 29.5 +/- 18.4 (6-76) months, lead failure occurred in 19 patients (8%), 16 patients were implanted with an ICD, capable of diagnostic and measurement functions. All nonadequate device discharges could be classified as sensing-failure by stored electrograms. Device implemented measurement features revealed clinical important information in 13/16 patients (81%). In 14/16 patients, the lead defect could not be detected during routine follow-up. At the time of documented lead failure the safety of the implanted devices was already lost in 6/16 patients (38%).

CONCLUSIONS

Device implemented diagnostic and measurement options are of great importance in the early detection of ICD lead failures. The implementation of automated measurements of lead related parameters in connection with a patient alert function may contribute to a further increase in the safety of ICD therapy.

Assessment of myocardial viability: Dobutamine echocardiography and thallium-201 single-photon emission computed tomographic imaging predict the postoperative improvement of left ventricular function after bypass surgery

The aim of this study was to evaluate the usefulness of dobutamine echocardiography and quantitative thallium-201 single photon emission computed tomography myocardial scintigraphy with reinjection in the detection of viable myocardium in patients with coronary artery disease and reduced left ventricular function, which will improve after aortocoronary bypass surgery. Forty-eight patients (47 men, aged 61 +/- 6 years) with angiographically documented reduced left ventricular function (ejection fraction 35 +/- 14, 63% with chronic transmural myocardial infarction) were examined by dobutamine two-dimensional echocardiography (before and during low dosage), 201Tl, and gated radionuclide ventriculography before and 3 +/- 2 months after aortocoronary bypass surgery. Four of 55 areas classified viable before operation were revascularized inadequately and discarded. Global left ventricular ejection fraction at rest rose from 35% +/- 14% before operation to 40% +/- 13% (p < 0.05) after operation. Stress-induced perfusion defects involved 40% +/- 19% of the left ventricle circumference after stress and showed a significant reduction of size to 23% +/- 14% (p < 0.01) at rest, 4 hours later, and after reinjection. This value fell to 16% +/- 12% (p < 0.05) 3 months after aortocoronary bypass surgery. We conclude that both dobutamine echocardiography (sensitivity 95%, specificity 80%, positive predictive value 87%, negative predictive value 88%) and 201Tl studies (sensitivity 87%, specificity 98%, positive predictive value 97%, negative predictive value 93%) are suitable and comparable accurate methods for predicting improvement in systolic function 3 months after revascularization in a selected population with a high prevalence of viable but hypokinetic or akinetic myocardium.

[Therapy with implanted cardioverter-defibrillator: Is a replacement of the impulse generator due to battery depletion also necessary without the occurrence of a tachyarrhythmia episode?]

The aim of this retrospective study was to evaluate the necessity of the replacement of an implantable cardioverter/defibrillator (ICD) in patients with pulse generator battery depletion without an adequate, spontaneous arrhythmia episode during the life-time of the first implanted device. In this study 213 patients with implanted ICDs were enrolled. In 62 patients an elective generator replacement due to battery depletion was performed. Both patient groups (Group A: patients with generator replacement n = 62 and Group B: patients without replacement n = 151) were not different with regard to main clinical characteristics, such as underlying heart disease and left ventricular function. In both groups there was a predominance of male patients (Group A: 89%; Group B: 83%). The mean age was 58 +/- 11 years and 59 +/- 11 years in Group A and Group B, respectively. Coronary artery disease was present in 66% and 68% of the patients. There was a comparable left ventricular ejection fraction: Group A: 30.5 +/- 9% vs Group B: 31.9 +/- 9%. The follow-up time was much longer in Group A patients compared to Group B patients (50.5 +/- 14 vs. 16.5 +/- 11 months). For the total patient group there was a 5 year event-free probability of 23%, no differences were found between both groups. The subanalysis in Group A patients revealed no difference in the probability of ICD-shock occurrence prior to or after the replacement of the pulse generator. In 48/62 (77%) of Group A patients adequate ICD discharges were documented. In 15/62 (24%) patients shock occurred before and after generator replacement. In 6/62 (10%) of Group A patients, the first adequate ICD-therapy was documented after generator replacement. The results of this study indicate the necessity of an ICD-pulse generator replacement even in patients without an adequate device discharge during the life-time of the first implanted device.

Hibernating myocardium: an incomplete adaptation to ischemia

BACKGROUND

We tested the hypothesis that hibernating myocardium represents an incomplete adaptation to a reduced myocardial oxygen supply.

METHODS AND RESULTS

In 38 patients, areas of hibernating myocardium were identified by angiography, multigated radionuclide ventriculography, thallium scintigraphy with reinjection, and low-dose dobutamine echocardiography. Biopsies removed at cardiac surgery showed structural degeneration characterized by a reduced protein and mRNA expression and disorganization of the contractile and cytoskeletal proteins myosin, actin, desmin, titin, alpha-actinin, and vinculin by electron microscopy, immunohistochemistry, and in situ hybridization. Additionally, an increased amount of extracellular matrix proteins resulting in a significant degree of reparative fibrosis was present. Dedifferentiation, ie, expression of fetal proteins, was absent. Apoptosis indicating suicidal cell death was found by the terminal deoxynucleotidyl transferase end-labeling method and electron microscopy. Radionuclide ventriculography showed improvement of regional function at 3 months postoperatively compared with preoperative values (mean values, 23.5% and 48%, respectively), and the echocardiographic wall-motion score index decreased from 3.4 to 1.8. The degree of severity of the morphological changes (three stages) correlated well with the extent of postoperative functional recovery: more advanced clinical improvement was observed in patients with slight and moderate morphological degeneration (stages 1 and 2), but recovery was only partial in severe degeneration (stage 3).

CONCLUSIONS

Cellular degeneration rather than adaptation is present in hibernating myocardium. The consequence is progressive diminution of the chance for complete structural and functional recovery after restoration of blood flow. The practical consequence from this study should be early revascularization in patients showing areas of hibernating myocardium.

Reoperations after dacron patch aortoplasty with heparinized femoro-femoral bypass

Dacron patch aortoplasty used to be a standard therapy in some surgical units. Occurrence of aneurysm formation after this procedure is well known. The incidence of aneurysms is reported to be 0-35% with a high risk of lethal rupture. We report three cases of aneurysm repair of the descending thoracic aorta after dacron patch aortoplasty using femoro-femoral extracorporeal system. Heparin-coated system was used primarily to prevent ischemic spinal cord injury through hypotension of the distal aorta and secondarily to reduce the risk of intraoperative hemorrhage.

Video-assisted resection of hypertrophied and fibrous intraventricular tissue

There is increasing interest in endoscopic techniques in cardiac surgery. However, use of the endoscope during open heart operations is still not routine. Cardioscopy has been used in patients with hypertrophied obstructive cardiomyopathy, asymmetric septal hypertrophy, or membranous subaortic stenosis. We demonstrate the resection of this pathologic tissue under direct visualization. With this technique we could increase the safety and accuracy of this surgical procedure. Beside this advantage, the entire operating room staff could follow the surgical intervention, which increases its educational side-effect.

Upregulation of cell adhesion molecules and the presence of low grade inflammation in human chronic heart failure

BACKGROUND

In the present study, the hypothesis was tested that cell adhesion molecules are expressed in failing human hearts and that a chronic inflammatory process contributes to chronic degeneration known to occur in cardiac incompetence. The cell adhesion molecules: ICAM-1, VCAM-1, PECAM-1, and E-selectin were studied, in addition to cellular markers of inflammation.

METHODS AND RESULTS

Tissue was obtained at transplantation from patients with either myocarditis, chronic ischaemic heart disease, or dilated cardiomyopathy. Controls were taken from patients with normal ventricles. Cell adhesion molecules were qualitatively evaluated and counted using specific antibodies and confocal microscopy. Additionally, semiquantitative evaluation of the presence of the CD3 antigen (T-lymphocytes), CD68 (macrophages), CD11a/CD18 (ICAM-1 receptor) and human tumour necrosis factor-a were used as indicators of chronic inflammation. PECAM-1 stained all endothelial cells but ICAM-1 was only present in 80% of all capillaries in control tissue. The ratio ICAM-1/PECAM-1 was significantly enhanced in all groups of diseased hearts. Myocytes in myocarditic hearts expressed ICAM-ICAM. CD3 positive lymphocytes, CD68 positive macrophages and CD11a/CD18 positive cells were more abundantly present than in control. Macrophages expressing tumour necrosis factor-a were found in failing myocardium but not in control tissue.

CONCLUSION

Independent of the cause of heart failure, chronic low grade inflammation is present in failing human myocardium. This may significantly contribute to the structural deterioration that is the basis of reduced cardiac function in congestive heart failure.

Diagnostic transaortic cardioscopy of the left ventricle

Preoperative diagnosis of pathologic intracardiac structures by noninvasive techniques is sometimes difficult or even impossible. In these cases a heart operation is required with opening of one or more cardiac chambers. We demonstrate direct visualization of the left ventricular cavity by transaortic cardioscopy in a patient with a pathologic intraventricular structure. With this technique we could avoid ventriculotomy.

Valve surgery combined with coronary artery operation: is the use of internal mammary artery a predictor for early complications?

The internal mammary artery (IMA) provides better early and long-term patency than venous grafts do. Although IMA is the conduit of choice in isolated coronary artery bypass grafting (CABG), its use in combined procedures is not routine in some cardiovascular units. During a 16-month period, 188 patients underwent valve surgery combined with CABG. Internal mammary grafts were used in 68/188 (36%) patients (group 1) and vein grafts without arterial grafts (group 2) in 120/188 (64%). Left IMA was implanted in 67/68 (99%) and right IMA in 1/68 1%) cases. Surgeon A used IMA in 28/44 (64%), surgeon B in 20/32 (63%), surgeon C in 18/44 (41%), surgeon D in 1/4 (25%) and surgeon E in 1/63 (2%) patients. The final decision to use IMA in a combined procedure was left up to the surgeon. Statistically, the preoperative- and perioperative data were identical in the two groups, although the frequency of IMA grafting in patients with double valve replacement and reoperation was lower (1/68 vs 11/120, ns, and 3/68 vs 9/120, ns). Ten of 188 (5.3%) patients died within 30 days after operation. Longer cross-clamp time (P = 0.008) and mitral valve replacement (P = 0.05) were independent risk factors for early death. The use of IMA did not increase the risk of early mortality. The postoperative variables were similar in the IMA and vein groups, in particular data suggesting perioperative myocardial infarction (CK-MB, catecholamine support). Postoperative mechanical ventilation was longer in the IMA group, although not significantly (P = 0.06). Early mortality and morbidity were identical in the two groups in combined procedures. We did not find any hints for an increased risk of using IMA in this type of surgery. Internal mammary artery implantation is safe in selected patients undergoing combined valve and CABG surgery. Beside the better long-term patency of IMA, its use may have several technical advantages.

Coronary arteriovenous fistula: surgical correction of a rare form

In a 60-year-old woman with long-standing angina left heart catheterisation revealed peripheral and central coronary arteriovenous fistulae connected to the left and right coronary system and opening into the pulmonary artery. The fistulae connected to terminal coronary artery branches were corrected by ligation of these feeding arteries while the electrocardiogram was continuously monitored. The central fistulae were closed via a transcoronary approach of the left anterior descending artery. Knowledge of different surgical techniques helps to prevent perioperative myocardial infarction and late fistula recurrence.

[Doppler and echocardiography parameters in detection of acute graft rejection after heart transplantation]

Due to the invasive nature of myocardial biopsies, a complication rate of up to 2.5%, and the limitations, e.g., at focal distribution of rejection, there is a continuous need for reliable, non-invasive parameters in recognizing moderate (grade 2) and severe (grade 3) acute cardiac allograft rejections in patients treated with cyclosporine A. 64 biopsies of 20 patients with previous heart transplantations in the past 3 weeks to 36 months (mean 11 months) were compared prospectively to Doppler and echocardiographic results. Parameters of systolic function such as percent fractional shortening (FS) and systolic wall thickness of the posterior wall (SWT) remained without significant changes at grade 2 and grade 3 rejections. The same is valid for relaxation parameters such as maximum velocity of posterior wall reduction (PTR), the time interval of endsystole to maximum velocity of posterior wall reduction (tES-PTR), and the isovolumic relaxation time (IVRT). Left-ventricular filling parameters such as maximum early diastolic flow velocity (VEmax) increased significantly from 73.3 +/- 15.2 cm/s in the rejection-free interval (grade 0) to 103.9 +/- 15.0 cm/s at grade 2 rejection and 101.1 +/- 9.2 cm/s at grade 3 rejection (both p < 0.001). A sensitivity of 50% and a negative predictive value of 77% are, however, too low to diagnose or exclude a moderate or severe acute rejection in the individual case.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial preservation using HTK solution for heart transplantation. A multicenter study

Bretschneider HTK solution is commonly used for myocardial preservation. In order to evaluate its protective effect for heart transplantation, a retrospective study was initiated in cooperation with Eurotransplant and five heart transplant centers. Seventy-six female and 524 male patients who underwent cardiac transplantations between 1981 and 1991 were included in this study. Using standardized questionnaires, donor and recipient laboratory data, immunosuppressive therapy and the preoperative, intraoperative and postoperative organ function were documented. The average ischemic time of the donor hearts was 160 min, ranging from 75 min-304 min. Immediate postoperative graft failure was observed in 25 transplantations (4.2%). Within the first 30 days 71 organs (11.8%) failed. Using the chi2-test, a statistically significant increase of acute graft failure and early mortality was evident when they were correlated with the length of ischemic time (P = 0.01). In addition, a higher incidence of early graft failure was observed when the perfusion volume was less than 1500 ml. The 1- and 5-year survival rates were 72% and 63%, respectively. Organ preservation with HTK shows good results as long as the ischemic time does not exceed 4 h. The possibility that an increased perfusion volume allows longer ischemic times cannot be excluded with this study.

Long-term results after right ventricular outflow tract reconstruction with porcine and allograft conduits

From 1975 to 1989, a total of 353 patients were operated for complex cardiac malformations with impaired pulmonary artery perfusion using 53 non-valved and 300 valved right heart to pulmonary artery conduits. In 108 patients a porcine conduit (Hancock or Carpentier-Edwards) 12-30 mm was used; the age range was 14 days to 37 years (mean 4.3 years) and body weight 2.9-68 kg (mean 15.3 kg). One hundred and ninety-two patients had an allograft of 9-29 mm implanted at the age of 17 days to 26 years (mean 3.8 years), body weight 2.7-73 kg (mean 14.2 kg). So far, 32 of the porcine valved conduits have had to be exchanged 2.5-10.5 years (mean 6.1 +/- 2.1 years) after the first implantation. In 3 patients, reoperated before 1982, another porcine valved conduit was used. After 1982, 29 exchanges were all performed using allografts. The main reason for xenograft conduit malfunction was degeneration and/or calcification of the valves. Some conduits, however, with rather small sizes of 12 and 14 mm had to be exchanged in spite of still sufficient function because the children had "outgrown" the conduit and needed a bigger one. Out of 192 patients with allografts implanted since 1982, so far 5 patients have had to be reoperated 2 months to 6 years (mean 4.6 +/- 2.8 years) after the first operation. The causes of allograft failure were degeneration and, in one case, infection of the conduit. Even though allografts seem to be the conduit of choice for right ventricular outflow tract reconstruction.(ABSTRACT TRUNCATED AT 250 WORDS)