Under-utilization of mechanical circulatory support in Canada: why and what can be done?

In October of 2002, a workshop was held as part of the Canadian Cardiovascular Congress in Edmonton, Canada, entitled "Under-Utilization of Mechanical Circulatory Support in Canada. Why and What Can Be Done?" The workshop examined various issues related to the use of mechanical circulatory support devices in the Canadian context. Representatives from all Canadian centers with active mechanical circulatory support programs were invited to participate and participants included surgeons and cardiologists, as well as other affiliated health professionals. Opinions were solicited from the workshop participants and a series of recommendations were formulated.

Ventricular assist devices as a bridge to cardiac transplantation: the Ottawa experience.

This article reports our experience with ventricular assist devices (VADs) as a bridge to cardiac transplantation. From 1991 to 2003, a total of 42 patients received a Thoratec VAD (Thoratec Laboratories Corporation Inc., Pleasanton, CA, U.S.A.) (Group T) and 12 patients received a Novacor VAD (WorldHeart Corporation, Ottawa, Canada) (Group N). Thirty Thoratec patients were transplanted compared to six in the Novacor group. Four more Novacor patients are still supported. Of the transplanted patients, 87% survived to hospital discharge in Group T and 67% in Group N. Infections affected 29% and 50% of Group T patients during support and post-transplantation, respectively, compared to 25% and 0%, respectively, in Group N. Neurologic complications affected 33% of patients in each group during support. Reopening rates for bleeding during support were 45% and 42% in Groups T and N, respectively. There were no significant differences in outcomes between the two groups. Our study demonstrated the effectiveness of VADs in bridging mortally ill cardiac patients to successful heart transplantation.

Patient selection for left ventricular assist devices.

The use of mechanical support as a bridge to cardiac transplant has become the standard of care in many cardiac transplant centers. This therapy has been shown to increase survival and improve morbidity in carefully selected patients waiting for heart transplantation. With approximately 30000 patients being listed worldwide for transplant every year and only 3500 transplantations performed annually, alternative strategies need to be developed to minimize morbidity and mortality in this high-risk population. Patient selection remains the primary determinant of success with left ventricular assist device (LVAD) therapy. This article will review both the cardiac and extracardiac considerations needed in the assessment of patient suitability for LVAD support as a bridge to transplantation.

Improved early survival with the total artificial heart.

We report our experience with the total artificial heart (TAH) to determine if outcomes have improved. Thirty-one patients received the TAH as a bridge to transplant and were divided into the two groups A (eighteen implanted in the first eight years) and B (thirteen implanted in the last eight years). Changes in management included immediate sternal closure, early extubation, delayed transplant listing, early rehabilitation, and measurement of preformed antibodies. The infection rate in B was lower than in A, both during support (31% versus 39%) and following transplant (38% versus 72%), and rejection was lower in B than in A (0% versus 44%). There was no difference in neurological events between groups; however, reopening was more frequent in B (61% versus 28%). Hospital survival increased from 61% in A to 85% in B; however, this was not statistically significant. We hypothesize that this improvement was likely due to changes in patient management.

Heart transplantation at the Ottawa heart institute: comparison with Canadian and international results.

Heart transplantation has been carried out in 340 patients in Ottawa, including seventy-one who required mechanical circulatory support as a bridge to transplant. Survival in Ottawa was compared with other Canadian centers based on data from the Canadian Organ Replacement Register up to the year 2000 and with the International Society of Heart and Lung Transplantation (ISHLT) registry 2001. For survival analysis, the number of adult patients at risk at year 0 was 303 (87 transplanted from 1985 to 1990, 105 from 1990 to 1994, and 111 from 1995 to 2000). The Statistical Analysis System (SAS) life test procedure was used. Survival was not adjusted for comorbidities or heart failure class. For the year of transplant 1985-1989, one-, five-, and ten-year patient survival in Ottawa was 83%, 70%, and 60%, respectively, compared to 82%, 71%, and 54%, respectively, for Canada (Wilcoxon test, P = 0.71), and compared to one- and five-year survival for ISHLT from 1980 to 1987 at 76% and 60%, respectively. For 1990-1994, one-, five-, and ten-year patient survival in Ottawa was 88%, 81%, and 74%, respectively, compared to 80%, 71%, and 61%, respectively, for Canada (P = 0.05), and compared to one- and five-year survival for ISHLT from 1998 to 1992 at 80% and 68%, respectively. For 1995-2000, one- and five-year patient survival in Ottawa was 90% and 82%, respectively, compared to 85% and 76%, respectively, for Canada (P = 0.09), and compared to one- and five-year survival for ISHLT from 1993 to 1996 at 82% and 68%, respectively. Survival after heart transplantation in Ottawa compares favorably with Canadian and international data.

Late incidence and predictors of persistent or recurrent heart failure in patients with aortic prosthetic valves.

BACKGROUND: We examined factors associated with persistent or recurrent congestive heart failure after aortic valve replacement. METHODS: Patients who underwent aortic valve replacement with contemporary prostheses (n = 1563) were followed up with annual clinical assessment and echocardiography. The effect of demographic, comorbid, and valve-related variables on the composite outcome of New York Heart Association class III or IV symptoms or congestive heart failure death after surgery was evaluated with stratified log-rank tests, Cox proportional hazard models, and logistic regression. Factors associated with all-cause death were also examined. Prediction models were bootstrapped 1000 times. RESULTS: Total follow-up was 6768 patient-years (mean, 4.3 +/- 3.3 years; range, 60 days to 17.1 years). Freedom from congestive heart failure or congestive heart failure death was 98.6% +/- 0.3%, 88.6% +/- 1.0%, 73.9% +/- 2.3%, and 45.2% +/- 8.5% at 1, 5, 10, and 15 years, respectively. Age, preoperative New York Heart Association class, left ventricular grade, atrial fibrillation, coronary artery disease, smoking, and redo status predicted congestive heart failure after surgery (all P <.05). Larger prosthesis size and effective orifice area, both absolute and indexed for body surface area, were independently associated with freedom from congestive heart failure. Increased transprosthesis gradients were predicted by prosthesis-patient mismatch and were associated with congestive heart failure after surgery. Mismatch defined as an effective orifice area/body surface area of 0.80 cm(2)/m(2) or less was a significant predictor of congestive heart failure events after surgery, but mismatch defined as an effective orifice area/body surface area of 0.85 cm(2)/m(2) or less was not. Small prosthesis size and mismatch were not significantly associated with all-cause mortality. CONCLUSIONS: These analyses identify independent predictors of congestive heart failure symptoms and congestive heart failure death late after aortic valve replacement and indicate that prosthesis size has a significant effect on this cardiac end point, but not on overall survival after aortic valve replacement.

In vivo evaluation of the biocompatibility of the totally implantable ventricular assist device (HeartSaver VAD).

A series of multicenter in vivo studies have been conducted to assess the biocompatibility and device performance of the HeartSaver VAD, a totally implantable pulsatile ventricular assist device (VAD). The experiments (n = 23) were conducted in calves with a mean weight of 101 (75-152) kg. Implants took place at four centers using two different surgical procedures of implantation (one with cardiopulmonary bypass and one without). Three anticoagulation regimens were used (one with continuous intravenous heparin, one with oral warfarin, and one with oral warfarin combined with antiplatelet clopidogrel therapy). Device function and biochemistry were monitored during the study, and organs and device analysis were conducted at explant. There were six nonsurvivors because of early surgical complications (during the first week of support). The postoperative courses in the remaining 17 (74%) calves were uneventful. Hemodynamic and biocompatibility indicators were monitored throughout the study. The mean duration of device support for those cases was 48 (13-92) days. Mean device flow was 7.15 (+/- 1.68) L/min. There were no deaths caused by infection; however, two animals developed endocarditis believed to be caused by the percutaneous instrumentation lines used for the study. No severe bleeding requiring reoperation occurred during the study. The mean plasma free hemoglobin was within normal limits at 6.8 +/- 2.6 mg/dl. Renal and hepatic functions were normal with a mean creatinine of 0.6 +/- 0.1 mg/dl and a mean aspartate aminotransferase of 68.7 +/- 42.6 mg/dl. Several device related improvements were identified and have now been implemented. Additional bovine implants with an optimized device are currently underway in preparation for human trials.

Mechanical circulatory support for adolescent patients: the Ottawa Heart Institute experience.

BACKGROUND: Mechanical circulatory support devices may be used for patients with end-stage heart failure for bridging either to cardiac transplant or to recovery of the native heart. While less common in adolescents, fulminant heart failure may be rapidly fatal in these patients unless circulatory support can be instituted. OBJECTIVES: To assess the outcomes and the utility of mechanical circulatory assist devices for children. METHODS: A retrospective review of pediatric patients (18 years of age or younger) who underwent circulatory support at the Ottawa Heart Institute, Ottawa, Ontario, from 1992 to 2001 was performed using chart audits. RESULTS: Seven patients (four boys, three girls) with a mean age of 14.9 +/- 0.9 years were supported with Thoratec ventricular assist devices (n=6) or a CardioWest total artificial heart (n=1). Preoperatively, the cardiac index was 1.64 +/- 0.2 L/min/m2 on one or two inotropes with ejection fractions of 11 +/- 2.2%. Mean duration of circulatory support was 59.3 +/- 17.2 days with a hospital length of stay of 89.6 +/- 12.8 days. All seven patients underwent successful transplantation and were discharged home. CONCLUSIONS: Pediatric patients with fulminant heart failure may be bridged to cardiac transplant successfully with mechanical circulatory support devices.

Isolated CABG in the Elderly: Operative Results and Risk Factors Over the Past Three Decades.

This chapter is reproduced from the book, Coronary Bypass Surgery in the Elderly, edited by Paul J. Walter. Reprinted by permission of Kluwer Academic Publishers. All Rights Reserved (c)1995 Kluwer Academic Publishers.