Identification of Streptococcus gallolyticus subsp. macedonicus as the etiological agent in a case of culture-negative multivalve infective endocarditis by 16S rDNA PCR analysis of resected valvular tissue

Today, PCR using broad-range primers is being used increasingly to detect pathogens from resected heart valves. Herein is described the first case of multivalve infective endocarditis where 16S rDNA PCR was used to detect a single pathogen from two affected valves in a 61-year-old man. Triple heart valve replacement was required despite six weeks of appropriate antimicrobial therapy. The organism was confirmed as Streptococcus gallolyticus subsp. macedonicus, a member of the 'S. equinus/S. bovis' complex. To date, only one report has been made of human infection due to this organism. This may be due to the limited resolution of the routine diagnostic methods used and/or as a consequence of the complex nomenclature associated with this group of organisms.

Factors influencing the outcome of paediatric cardiac surgical patients during extracorporeal circulatory support

BACKGROUND

Veno-arterial extracorporeal membrane oxygenation (ECMO) is a common modality of circulatory assist device used in children. We assessed the outcome of children who had ECMO following repair of congenital cardiac defects (CCD) and identified the risk factors associated with hospital mortality.

METHODS

From April 1990 to December 2003, 53 patients required ECMO following surgical correction of CCD. Retrospectively collected data was analyzed with univariate and multivariate logistic regression analysis.

RESULTS

Median age and weight of the patients were 150 days and 5.4 kgs respectively. The indications for ECMO were low cardiac output in 16, failure to wean cardiopulmonary bypass in 13, cardiac arrest in 10 and cardio-respiratory failure in 14 patients. The mean duration of ECMO was 143 hours. Weaning off from ECMO was successful in 66% and of these 83% were survival to hospital-discharge. 37.7% of patients were alive for the mean follow-up period of 75 months. On univariate analysis, arrhythmias, ECMO duration >168 hours, bleeding complications, renal replacement therapy on ECMO, arrhythmias and cardiac arrest after ECMO were associated with hospital mortality.On multivariate analysis, abnormal neurology, bleeding complications and arrhythmias after ECMO were associated with hospital mortality. Extra and intra-thoracic cannulations were used in 79% and 21% of patients respectively and extra-thoracic cannulation had significantly less bleeding complications (p = 0.031).

CONCLUSION

ECMO provides an effective circulatory support following surgical repair of CCD in children. Extra-thoracic cannulation is associated with less bleeding complications. Abnormal neurology, bleeding complications on ECMO and arrhythmias after ECMO are poor prognostic indicators for hospital survival.

Mitral valve repair for active culture positive infective endocarditis

OBJECTIVE

To describe the clinical and echocardiographic outcome after mitral valve (MV) repair for active culture positive infective MV endocarditis.

PATIENTS AND METHODS

Between 1996 and 2004, 36 patients (mean (SD) age 53 (18) years) with positive blood culture up to three weeks before surgery (or positive culture of material removed at operation) and intraoperative evidence of endocarditis underwent MV repair. Staphylococci and streptococci were the most common pathogens. All patients had moderate or severe mitral regurgitation (MR). Mean New York Heart Association (NYHA) class was 2.3 (1.0). Follow up was complete (mean 38 (19) months).

RESULTS

Operative mortality was 2.8% (one patient). At follow up, endocarditis has not recurred. One patient developed severe recurrent MR and underwent valve replacement and one patient had moderate MR. There were two late deaths, both non-cardiac. Kaplan-Meier five year freedom from recurrent moderate to severe MR, freedom from repeat operation, and survival were 94 (4)%, 97 (3)%, and 93 (5)%, respectively. At the most recent review the mean NYHA class was 1.17 (0.3) (p < 0.0001). At the latest echocardiographic evaluation, left atrial diameters, left ventricular end diastolic diameter, and MV diameter were significantly reduced (p < 0.05) compared with preoperative values.

CONCLUSIONS

MV repair for active culture positive endocarditis is associated with low operative mortality and provides satisfactory freedom from recurrent infection, freedom from repeat operation, and survival. Hence, every effort should be made to repair infected MVs and valves should be replaced only when repair is not possible.

Venovenous extracorporeal membrane oxygenation for respiratory failure in inotrope dependent neonates

It is often stated that venovenous extracorporeal membrane oxygenation (VV ECMO) should not be used in inotrope dependent patients. It is our practice to use VV ECMO in most patients with respiratory failure even though many of these patients are receiving significant doses of inotropes. Our objective was to review the mode of ECMO in relation to precannulation doses of inotropes administered to neonates treated with ECMO for respiratory failure. Forty-three consecutive case notes were reviewed. Data were collected for basic demographic and ECMO parameters. Inotropic doses were converted to a single score for ease of comparison, with one point equivalent to 1 microg/kg/min dopamine. Forty-three neonates were studied; 37(86%) were treated with VV ECMO and 6 (14%) were treated with VA ECMO. Significant pre-ECMO inotropic support (score > 10) was present in 30 (70%) of the 43 cases. Of these patients, 26 were treated via VV ECMO with a survival rate of 84%, while 4 were treated with VA ECMO with a survival of 75%. Inotrope scores fell to nonsignificant levels (< 10) within 24 hours, regardless of ECMO mode. Mean arterial blood pressure remained above precannulation levels in both groups. VV ECMO allows safe treatment of neonatal respiratory failure in the presence of significant inotropic support. We recommend VV ECMO for neonatal respiratory failure in all cases except where double lumen cannulation is impossible or when septic shock is refractory to inotropic support (i.e., mean blood pressure < 35 mm Hg despite inotrope score of > 100).

Does the type of prosthesis influence early left ventricular mass regression after aortic valve replacement? Assessment with magnetic resonance imaging

BACKGROUND

Debate exists regarding selection of the prosthesis type most likely to maximize early left ventricular (LV) mass regression after aortic valve replacement (AVR) for stenotic valvular disease. The aim of this study was to compare the degree of LV mass regression measured by MRI 6 months after prospectively randomized valve implantation for two biological prostheses, stented and stentless, and for two mechanical valves, tilting disc and bileaflet.

METHODS

Thirty-nine consecutive patients with predominant aortic stenosis accepted for elective AVR were studied. Twenty patients requiring a tissue prosthesis were randomly assigned to receive either a Freestyle or Mosaic valve. The remaining 19 patients in whom mechanical prosthesis was indicated were randomly assigned to receive either an Ultracor or an ATS valve.

RESULTS

There was no difference in valve size implanted between the compared groups. LV mass measurements were performed with MRI (1.5-T Vision, Siemens, Germany) immediately before and 6 months after surgery. All valve types produced significant postoperative reduction in LV mass compared with preoperative values (P <.01). Percent change in LV mass regression was similar between the two porcine valve types, Mosaic (24.4% +/- 11.1%) and Freestyle (21.1% +/- 16.7%), and between the two mechanical valve designs, Ultracor (19.3% +/- 9.5%) and ATS (26.3% +/- 10.8%), respectively.

CONCLUSIONS

Significant LV remodeling occurs early after AVR for aortic stenosis. The degree of regression in LV mass is independent of prosthesis type implanted.

Postoperative extracorporeal membrane oxygenation for severe intraoperative SIRS 10 h after multiple trauma

A 34-yr-old male suffered multiple trauma in a road traffic accident. He required right thoracotomy and laparotomy to control exanguinating haemorrhage, and received 93 u blood and blood products. Intraoperatively, he developed severe systemic inflammatory response syndrome (SIRS) with coagulopathy and respiratory failure. At the end of the procedure, the mean arterial pressure (MAP) was 40 mm Hg, arterial blood gas analysis showed a pH of 6.9, Pa(CO(2)) 12 kPa, and Pa(O(2)) 4.5 kPa, and his core temperature was 29 degrees C. There was established disseminated intravascular coagulation. The decision was made to stabilize the patient on veno-venous extracorporeal membrane oxygenation (ECMO) only 10 h after the accident, in spite of the high risk of haemorrhage. The patient was stabilized within 60 min and transferred to the intensive care unit. He was weaned off ECMO after 51 h. He had no haemorrhagic complications, spent 3 weeks in the intensive care unit, and has made a good recovery.

Hemodynamic performance after stented vs stentless aortic valve replacement

BACKGROUND

Stentless bioprostheses are anticipated to cause improved hemodynamics and increased longevity over stented bioprosthesis. We have compared echocardiographic analysis of stented bioprosthesis "Freestyle" with stented "Mosaic" bioprosthesis. Because of similar technology (0 pressure fixation, anticalcification) any differences may relate to stent.

METHODS

Twenty-eight patients undergoing AVR were randomly assigned to receive either stented or stentless. Echocardiograms, by means of M-mode and Doppler were performed early, 3-6 months and 1 year postoperatively.

RESULTS

The peak flow velocity was significantly lower in the stentless group, especially 1 week and 6 months after surgery. Mean transvalvular gradient dropped significantly in stentless group and did not change in stented group. EOA did not change significantly in either of groups. AoV velocity time integral was increasing in stentless group. LV mass had fallen significantly in both groups but degree of mass reduction was comparable.

CONCLUSIONS

There are marked improvements of stentless valves hemodynamics. However it is not necessary equal to higher degree of LV mass reduction during 1 year follow-up.

Post infarction ventricular septal defect - can we do better?

OBJECTIVE

To identify predictors of early and late outcome among 117 consecutive patients who underwent postinfarction ventricular septal defect (VSD) repair over a period of 12 years.

METHODS

A retrospective analysis of clinical data was performed. Mean age was 65.5+/-7.8. There were 43 females. Full data were obtained in 110 patients. Of these, 76 patients presented with anterior and 34 with posterior VSD. Thirty-three patients were operated in cardiogenic shock. Mean time between myocardial infarction (MI) and VSD development was 5.6+/-7.8 days (median 4) and from VSD to surgery 9. 0+/-28.1 (median 2). Sixty-six patients had intraaortic balloon pump (IABP) inserted, and 15 were ventilated preoperatively. Logistic regression and Cox regression were used for multivariate analysis.

RESULTS

Thirty days mortality was 37%. Among 110 patients, in whom complete analysis was possible, 38 died within 30 days (35%). Mortality in the posterior VSD group was 35% and in the anterior VSD group 34% (NS). In 44 patients (40%) a residual shunt was found on postoperative echocardiography. This required reoperation in 13 patients (four deaths). Cardiogenic shock prior to surgery adversely influenced early survival - odds ratio (OR) 5.7 (confidence interval (CI) 2.1-16.0) (P=0.0008). Deterioration of haemodynamic status in between admission and surgery was stronger predictor of mortality than shock on admission - OR 6.0 (CI 1.6-22.6) (P=0.008) vs. 3.1 (CI 1.0-9.3) (P=0.049). A longer time between MI and surgery favoured survival - OR 0.1 (CI 0.03-0.4) (P=0.002). The time period from the infarct to the septal rupture, but not from the rupture to surgery, appeared to be a significant predictor of survival - OR 0.2 (CI 0. 05-0.6) (P=0.008). Five years survival was 46+/-5%. Preoperative cardiogenic shock affected late survival - OR 2.7 (CI 1.5-4.9) (P=0. 001). Of 72 patients who survived 30 postoperative days, 12 (17%) were in New York Heart Association (NYHA) class III or IV and five (6.9%) in Canadian Cardiovascular Soceity (CCS) class III or IV at the last follow-up.

CONCLUSIONS

Preoperative cardiogenic shock and early postinfarction septal rupture carry a grave prognosis. Achieving haemodynamic stability prior to surgery may be beneficial but prolonged attempts to improve patients' cardiovascular state are hazardous.

"Mosaic" medtronic bioprosthetic valve replacement clinical results and hemodynamical performance

BACKGROUND

We report the mid-term results of a prospective trial of a new bioprosthetic valve. The Mosaic bioprosthesis consists of porcine aortic valve that has been cross linked ed in glutaraldehyde solution under zero-pressure fixation and treated with alpha amino oleic acid to reduce the potential for calcification.

METHODS

Mosaic bioprosthetic valve replacement was performed in 67 consecutive patients between January 1995 and August 1998. There were 37 patients having aortic valve replacement (AVR) and 30 having mitral valve replacement (MVR) who entered this study. The patients age ranged 56 to 86 years (mean 74.9); 38 were female and 29 were male; 44 were in NYHA grade 3 and 21 were NYHA grade 4. All mitral valve replacements were performed with total preservation of subvalvular apparatus. Echocardiographic assessment of valve and LV function were performed on 7th day, 6 months 1,2 and 3 years.

RESULTS

There was no hospital mortality. 3 year survival was 85.9+/-5.9% for AVR and 100% for MVR. Freedom from antithromboembolic related haemorrhage has been 96.7% for MVR and 91.9% for AVR. Freedom from the transient neurological event was 96.7+/-3.3% for MVR and 100% for AVR Freedom from structural valve failure, permanent thromboembolism, thrombosis or endocarditis has been 100% for both AVR and MVR. In AVR group left ventricle mass, left ventricle mass index significantly decreased, when cardiac index and effective orifice area increased significantly during study period. Transvalvular gradient did not change. In MVR group transvalvular gradient, effective orifice area and cardiac index did not change.

CONCLUSIONS

The valve was user friendly. The early results are very satisfactory. Echocardiography measurements after aortic valve replacement are showing very marked late postoperative remodelling of left ventricle. After mitral valve replacement there were exceptionally low transvalvular gradients, no left ventricle outflow tract obstruction.

Off-pump bypass graft operation significantly reduces oxidative stress and inflammation

BACKGROUND

This study investigated whether off-pump coronary bypass graft operations on the beating heart under normothermic conditions reduces the systemic oxidative stress and inflammatory reaction seen in patients operated under cardiopulmonary bypass (CPB).

METHODS

A cardiac stabilizer (Octopus Tissue Stabilizer; Medtronic Inc, Minneapolis, MN) was used to perform the coronary anastomoses on the normothermic beating heart with or without CPB. Serial blood samples were taken at various intervals. Plasma was analyzed for several oxidative stress and inflammatory markers.

RESULTS

Significant increases from prior anesthesia values of lipid hydroperoxides (190% at 4 hours), protein carbonyls (250% at 0.5 hours) and nitrotyrosine (510% at 0.5 hours) were seen in the CPB group, but they were abolished or significantly reduced in the off-pump group. Complement C3a and elastase levels were rapidly increased upon the institution of CPB, and this was followed by increases in IL-8, TNF-alpha, and sE-selectin. In contrast, the rise of these factors was blunted in patients operated without CPB.

CONCLUSIONS

Off-pump coronary bypass graft operation on a beating heart significantly reduces oxidative stress and suppresses the inflammatory reaction associated with the use of CPB.

Modifying a venovenous extracorporeal membrane oxygenation circuit to reduce recirculation

Lung rest is the primary goal of venovenous extracorporeal membrane oxygenation for severe acute respiratory failure. To achieve this there has to be adequate extracorporeal flow. This can be achieved by a two-cannula technique in most cases. In some cases, extra flow is either not achievable or causes excessive recirculation. We report 8 patients in whom we achieved adequate blood and oxygen delivery using a three-cannula technique. Five patients survived (62.5%).

Extracorporeal membrane oxygenation: potential for adults and children?

Extracorporeal membrane oxygenation is a proven therapy for severe neonatal respiratory failure. Extracorporeal membrane oxygenation for older children and adults who are failing to respond to maximal conventional therapy is more controversial, but survival figures of 50-80% can be obtained, in patients with an expected survival of 0-20% with conventional treatment.

Severe acute respiratory distress syndrome secondary to acute pancreatitis successfully treated with extracorporeal membrane oxygenation in three patients

OBJECTIVE

To review three patients who underwent extracorporeal membrane oxygenation (ECMO) for acute respiratory failure secondary to pancreatitis.

SUMMARY BACKGROUND DATA

Severe acute pancreatitis often causes the acute respiratory distress syndrome (ARDS), and if ventilation is required, the mortality rate is more than 50%. If the ratio of PaO2/FiO2 falls below 100 mm Hg or the Murray lung injury score exceeds 3.5, the mortality rate rises to more than 80%. Three patients who have severe ARDS secondary to pancreatitis, who were hypoxic despite ventilation with 100% oxygen and high airway pressures, and who were all successfully treated with ECMO are reported here. The consensus here is that all three patients would have died without ECMO.

METHODS

Retrospective chart review and discussion of the literature.

RESULTS

Pre-ECMO data: mean PaO2/FiO2 59.3 mm Hg, mean Murray lung injury score 3.7, one patient administered 20 ppm inhaled nitric oxide. ECMO data: mean extracorporeal flow at initiation of ECMO 56.3 mL/kg per minute, all patients administered veno-venous ECMO, mean duration of ECMO 104.7 hours. All patients were successfully weaned from ECMO and extubated. One patient had a protracted hospital stay because of a colo-cutaneous fistula. All patients are long-term survivors.

CONCLUSIONS

Extracorporeal membrane oxygenation proved an effective therapy for severe ARDS complicating acute pancreatitis. Extracorporeal membrane oxygenation was conducted without bleeding complications in these three patients.

Extracorporeal membrane oxygenation for adult respiratory failure

OBJECTIVES

To review the first 50 patients to receive extracorporeal membrane oxygenation (ECMO) for respiratory failure at Glenfield Hospital, and to compare them with published series of patients receiving positive pressure ventilation.

DESIGN

Retrospective chart review.

SETTING

Extracorporeal Life Support Organization/European Extracorporeal Life Support Organization recognized ECMO center.

PATIENTS

Fifty consecutive patients referred for ECMO with respiratory failure refractory to conventional management between 1989 and 1995.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Primary end point was survival to hospital discharge, 66%. Other data (mean and SD): Murray Lung Injury Score, 3.4 (0.5); ratio of PaO2 to fraction of inspired oxygen, 65 (36.9) mm Hg; duration of ventilation pre-ECMO, 76.5 (83.7 h); peak airway pressure, 39.6 (7.4) cm H2O; end-expiratory pressure, 10 (3.3) cm H2O; minute ventilation, 12.6 (3.32) L/min; age, 30.1 (10.8) years; duration of ECMO, 207.4 (177.8) h; and units of blood transfused, 19 (17.3). Survival was significantly better than two previously reported series of patients receiving positive pressure ventilation (55.6% and 42% survival), p=0.036 and p=0.0006. Odds ratio for improved survival was 0.46 (95% confidence interval, 0.22 to 0.97, p=0.036).

CONCLUSIONS

Survival with ECMO is 66% for adults with severe respiratory failure. ECMO should be considered in patients who remain hypoxic despite maximal positive pressure ventilation.

Extra-corporeal membrane oxygenation for paediatric respiratory failure

Extracorporeal membrane oxygenation (ECMO) uses modified cardiopulmonary bypass technology to provide prolonged respiratory or cardiorespiratory support for patients of all ages who have failed conventional intensive care management. The use of ECMO for neonatal respiratory failure is now evidence-based following the publication of the randomised UK Collaborative Trial. ECMO use in children remains more controversial, but overall survival of 71% is possible in a group of moribund patients whose mean PaO2/FIO2 ratio of 61 mmHg accurately predicts death in studies of conventional ventilation. Common diagnoses for children requiring ECMO support are pneumonia and the acute respiratory distress syndrome (ARDS).

Cannulation of neonates for venovenous extracorporeal life support

Venovenous access via a double-lumen cannula in the right internal jugular vein is the extracorporeal life support mode of choice for neonates with respiratory failure. We report a simplified method of cannulation. The advantages of this "semi-Seldinger" method include the ability to cannulate without ligating the internal jugular vein, and to adjust the position of the cannula and decannulate without re-exploring the wound.

Extracorporeal membrane oxygenation for the treatment of massive pulmonary embolism

After witnessing the death of a patient following pulmonary embolectomy, John H. Gibbon, Jr, developed the idea of a device for extracorporeal oxygenation and circulation. What followed has led to the present-day method of extracorporeal membrane oxygenation as an effective method of cardiorespiratory support. In this case of massive acute pulmonary embolism, its use in a conscious patient completes the circle from the first ideas of Gibbon.