Mediastinitis due to Gram-negative bacteria is associated with increased mortality.

The aim of this study was to describe the features of a large cohort of patients with postoperative mediastinitis, with particular regard to Gram-negative bacteria (GNB), and assess their outcome. This bicentric retrospective cohort included all patients who were hospitalized in the Intensive Care Unit with mediastinitis after cardiac surgery during a 9-year period. Three hundred and nine patients developed a mediastinitis with a mean age of 65 years and a mean standard Euroscore of six points. Ninety-one patients (29.4%) developed a GNB mediastinitis (GNBm). Of the 364 pathogens involved, 103 GNB were identified. GNBm were more frequently polymicrobial (44% versus 3.2%; p <0.001). Being female was the sole independent risk factor of GNBm in multivariate analysis. Initial antimicrobial therapy was significantly more frequently inappropriate with GNBm compared with other microorganisms (24.6% versus 1.9%; p <0.001). Independent risk factors for inappropriateness of initial antimicrobial treatment were GNBm (OR = 8.58, 95%CI 2.53-29.02, p 0.0006), and polymicrobial mediastinitis (OR = 4.52, 95%CI 1.68-12.12, p 0.0028). GNBm were associated with more drainage failure, secondary infection, need for prolonged mechanical ventilation and/or use of vasopressors. Thirty-day hospital mortality was significantly higher with GNBm (31.9 % versus 17.0%; p 0.004). GNBm was identified as an independent risk factor of hospital mortality (OR = 2.31, 95%CI 1.16-4.61, p 0.0179).

Immunologic events and long-term survival after combined heart and kidney transplantation: a 12-year single-center experience.

BACKGROUND: In this study we compare the incidence of cardiac rejection and long-term survival after combined heart and kidney transplantation (HK) and single heart transplantation (H). Combined HK transplantation is a surgical option for patients with irreversible cardiac and renal failure. However, long-term results of combined HK transplantation on immunologic events and patient survival remain unknown. METHODS: Between 1988 and 1997, 12 consecutive patients underwent combined HK transplantation (HK group) at a single institution. A control group (H group) of 24 single heart transplant recipients operated on within the same period was matched for age, pre-operative pulmonary vascular resistance, hepatic insufficiency and gender mismatch. Recipients and donors were ABO compatible without HLA antigen matching. All patients received immediate triple immunosuppression that included cyclosporine. Because of early renal dysfunction, cyclosporine was switched to anti-thymocyte globulin in 5 patients from the HK group and in 1 patient from the H group (p = 0.01). RESULTS: Actuarial freedom from heart rejection at 6 months and at 1 year following transplantation averaged 90 +/- 9% and 70 +/- 14% in the HK group, and 65 +/- 10% and 49 +/- 11% in the H group, respectively (p = 0.023). Actuarial survival at 1, 5 and 12 years was not significantly different between groups, at 66%, 55% and 28% in the HK group, and 66%, 44% and 32% in the H group, respectively (p = 0.66). CONCLUSION: The incidence of cardiac rejection was significantly lower. Long-term survival in the HK group was similar to that in the H group. Putative mechanisms of decreased cardiac rejection in the HK group include allogeneic stimulation, donor-derived dendritic cells and induction by anti-thymocyte globulins. The need for long-term immunosuppression may be reduced after combined heart and kidney transplantation.

[External ventricular support in primary cardiogenic shock]. / Dérivations ventriculaires externes dans le choc cardiogénique primaire.

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.

Cardiac troponin I release after open heart surgery: a marker of myocardial protection?

BACKGROUND: Unlike creatine kinase MB isoenzyme, cardiac troponin I (cTnI) is a highly specific marker of myocardial injury. Its release has recently been studied after coronary artery bypass grafting operation. However, its significance after open heart surgery (OHS) remains to be determined. This protein release could be a marker of myocardial protection. We sought to study cTnI release after OHS in patients with normal coronary arteries and to compare it with cTnI release in patients after coronary artery bypass graft (CABG) surgery. METHODS: Eighty-five patients undergoing OHS and 86 patients undergoing CABG were enrolled in the study. CTnI concentrations were measured in serial venous blood samples drawn before surgery and immediately, 12 hours, 24 hours, 48 hours, and 5 days after aortic unclamping. RESULTS: In the OHS group and in the CABG group without acute myocardial infarction (AMI), cTnI peaked at 12 hours postoperatively (6.35 +/- 6.5 and 5.38 +/- 8.55 ng/mL, respectively) and normalized on day 5 postoperatively (0.57 +/- 2 and 0.72 +/- 1.62 ng/mL, respectively). CTnI concentration did not differ significantly between the OHS group and the CABG group in the absence of AMI for any samples considered. In the CABG group, 2 patients had AMI. In the OHS group, cTnI levels at 12 hours postoperatively were found to correlate closely with CPB and aortic cross-clamping (ACC) times, contrary to the CABG group, which correlated only with occurrence of AMI. CTnI release was independent of age and ejection fraction in either group. CONCLUSIONS: cTnI release in patients after OHS with normal coronary arteries has the same profile as cTnI release in patients after CABG in the absence of AMI. However, its peak at 12 hours postoperatively is only correlated to ACC and CPB times, which is contrary to cTnI release after CABG surgery. This observation suggests that cTnI could be a marker of myocardial ischemia after OHS.

Doppler tissue imaging to predict myocardial recovery during mechanical circulatory support.

Bridge to recovery is a possibility for patients receiving mechanical circulatory support. However, no reliable factors exist to predict a sustained myocardial recovery. We report the use of a new technique of Doppler tissue imaging to document myocardial recovery in two cases with promising results.

Lack of durability of the Mitroflow valve does not affect survival.

BACKGROUND AND AIM OF THE STUDY: The aim of the study was to compare the durability and risk of reoperation in patients undergoing isolated aortic valve replacement with either a porcine standard Carpentier Edwards or a Mitroflow pericardial valve. METHODS: Follow up evaluation was performed in 118 patients receiving a Mitroflow valve (M) and 94 patients receiving a standard Carpentier Edwards porcine valve (CE) between 1980 and 1987. The two groups were identical in terms of clinical characteristics; only prosthesis size differed, with small-sized valves used more frequently among the Mitroflow group. RESULTS: The risk of structural valve deterioration (SVD) was 2.3% per patient-year (pt-yr) in CE valves, and 5.4 per pt-yr in M valves. Freedom from SVD was 100%, 87 +/- 4% and 63 +/- 8% at 5, 10 and 15 years for CE valves, and 96 +/- 2%, 56 +/- 7% and 5 +/- 4% for M valves. Freedom of reoperation was 98 +/- 1%, 83 +/- 5% and 76 +/- 7% at 5, 10 and 15 years respectively for CE valves, and 94 +/- 2%, 55 +/- 7% and 11 +/- 9% for M valves. Despite the high number of valve-related reoperations, survival at 5, 10 and 15 years was not affected in M valve patients. Multivariate analysis (Cox model) showed that age and valve type were the two main risk factors for SVD and reoperation, though the latter factor had no impact on survival. CONCLUSIONS: In younger patients (aged < 75 years), the CE valves offer superior results to the M counterpart in valve replacement. However, in patients aged > 75 years, pericardial and porcine bioprostheses demonstrate equivalent durability, despite post-implantation tissue changes in the former material.

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.

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.

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.

Mechanical circulatory support towards the permanent implantation.

Experience on wearable LVAS Novacor support accumulated since the first implantation in March 1993, includes in November 1995, seven cases (six male, one female, mean age 34) of cardiogenic shock, unresponsive to optimal medical management referred for urgent transplantation. Post-implantation period was free of any major incident in all but one, allowing transplantation in five, on an elective basis, and prolongation of the waiting period, at home in two. This experience suggests that a major breakthrough in the technology of mechanical support has been achieved: patients awaiting transplantation can be discharged home, which is both the result and an contributing factor of a satisfactory quality of life. This improvement allows speculations on coming studies on permanent implantation of the wearable LVAS Novacor, as an alternative therapy to cardiac transplantation.

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.

[Indication of mechanical circulatory assistance]. / Indication de l'assistance circulatoire mécanique.

Over the last decade, we have seen considerable progress both in medical treatment of acute and chronic heart failure and in circulatory assist systems, including the first used aorta counter-pulse system. More sophisticated systems have been developed with specific indications recognized by specialized teams. However, in the treatment of chronic heart failure, whether caused by idiopathic dilated cardiomyopathies or ischemic heart disease (frequently improved with coronary revascularization), the nature of the disease in patients hospitalized in intensive care units has greatly changed. There is a net tendency towards hospitalizing older patients who may no longer be reasonable candidates for transplantation. The option of circulatory assist is thus undoubtedly reasonable for these patients due to the lack of a sufficient number of donor organs.

[Wearable Baxter-Novacor mechanical ventricular assistance]. / L'assistance mécanique ventriculaire portable, type Baxter-Novacor.

Progressive technological developments have permitted clinical use of the wearable Baxter-Novacor left ventricular assist system. The system allows total bypass of the left ventricular function, and recovery of and adequate circulation in patients in cardiogenic shock. Since the first clinical use, in March 1993, eight patients about to die have been supported with a cardiac transplantation. This experience suggests that an an acceptable answer to the problem of organ shortage is now available.

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.

[Mechanical circulatory assistance using the Novacor implanted device. A postoperative follow-up]. / Assistance circulatoire mécanique par dérivation ventriculaire gauche implantée type Novacor. Suivi postopératoire.

The postoperative follow-up of 8 patients on the waiting list for cardiac transplantation, with implanted left ventricular assist devices of the Novacor type, was marked by right ventricular failure in the first week, controlled by positive inotropic agents and the maintenance of high right ventricular preload. The outcome later on showed that an ambulatory life was possible for 6 of the 8 patients, allowing the wait for cardiac transplantation under excellent conditions. Three major complications were observed: a case of aspergillosis endocarditis, one vertebrobasilar cerebrovascular accident and one low output state by progressive degradation of right ventricular function: after a period of circulatory assistance of 52 to 201 days. 6 out of the 8 patients underwent cardiac transplantation, 5 of which were successful.

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.

[Wearable mechanical ventricular support]. / L'assistance mécanique ventriculaire portable.

Progressive technological developments have permitted clinical use of the wearable Baxter-Novacor left ventricular assist system. The system allows total bypass of the left ventricular function, and recovery of an adequate circulation in patients about in cardiogenic shock. Since the first clinical use, in March 1993, six patients about to die have been supported with a cardiac transplantation. This experience suggests that an acceptable answer to the problem of organ shortage is non available.

[Orthotopic cardiac transplantation with caval anastomosis: a comparative randomized study with standard procedure in 81 cases]. / Transplantation cardiaque orthotopique avec anastomoses caves: étude randomisée comparative avec la technique standard sur 81 procédures.

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.

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.