Cardiac transplantation after mechanical circulatory support: a Canadian perspective

Characteristics and Outcomes of Patients Bridged to Cardiac Transplantation on Centrifugal Ventricular Assist Devices: A Case Series of the Early Experience of One Canadian Transplant Centre

BACKGROUND

Centrifugal ventricular assist devices (VADs) have been used successfully to bridge patients in cardiogenic shock to cardiac transplantation, though complications are frequent and often life-threatening.

PURPOSE

To describe characteristics and examine outcomes of patients bridged to cardiac transplantation on centrifugal VADs.

METHODS

A retrospective health record review was conducted on all adults over a 12 year period (N=20) placed on centrifugal VADs with the intent to bridge to cardiac transplantation at a major Canadian transplant centre.

RESULTS

Complications of VAD support necessitated removal of 12 patients from the transplant list; seven (35%) survived to cardiac transplantation. Of the seven recipients, five survived to discharge and four remain alive and well.

CONCLUSIONS

Bridging patients on centrifugal VADs to cardiac transplantation requires improvement, including maintaining patient stability during the period of early VAD institution, aggressively managing complications of VAD support, and consideration of long-term pulsatile devices. However, if patients survive to transplantation, good long-term outcomes are expected.

Results following implantation of mechanical circulatory support systems: the Montreal Heart Institute experience

BACKGROUND

Mechanical circulatory support systems (MCSS) have been available in Canada since 1986. Accepted indications include bridging to transplantation or recovery. The present study reviewed the results following MCSS implantation at the Montreal Heart Institute (Montreal, Quebec).

METHODS

From September 1987 to September 2006, 43 MCSS were implanted (32 Thoratec [Thoratec Corporation, USA], nine CardioWest TAH [SynCardia Systems Inc, USA], two Novacor [WorldHeart Corporation, Canada]) in 43 patients (mean [+/- SD] age 44+/-13 years; range 19 to 64 years). Indications for implantation included cardiogenic shock due to ischemic (n=19), viral (n=10) or other types of cardiomyopathies (n=14).

RESULTS

The mean ejection fraction before implantation was 17.6+/-6.5% (range 10% to 45%). Before MCSS implantation, most patients showed signs of end-organ failure, including mechanical ventilation (77%), central venous pressure higher than 16 mmHg (44%), oliguria (35%) and hepatic dysfunction (19%). The mean duration of MCSS support was 22.8+/-32.8 days (range one to 158 days). Survival to transplantation or recovery was 74%. Only one patient was successfully bridged to recovery. Complications were common during MCSS support. They included reexploration for bleeding (47%), respiratory failure (44%), renal failure requiring temporary dialysis (40%), infection (33%) and neurological events (16%). Only one patient had device failure. In patients successfully bridged to transplantation, early actuarial survival (one month) following transplantation averaged 71+/-8% and was 57+/-9% at one year.

CONCLUSION

MCSS support with a left ventricular assist device or a total artificial heart provides an effective means of bridging terminally ill patients to transplantation or recovery. Early survival after transplantation shows satisfactory results. However, these results come at the expense of frequent device-related complications, and device failure remains a constant threat.

Heart transplantation in children after mechanical circulatory support with pulsatile pneumatic assist device

BACKGROUND

Mechanical support with a pulsatile pneumatic ventricular assist device (VAD) is a complex rescue procedure performed in children with untreatable cardiogenic shock. Its impact on early and long-term survival after subsequent heart transplantation (HTx) remains to be determined.

METHODS

We reviewed retrospectively the course of 95 children (median age, 8 years; range, 8 days-17 years; body weight, 24 kg; range, 3-110 kg) who underwent HTx. Group A, the elective-HTx group, consists of 33 children who were treated as outpatients before transplantation. Group B, the emergency-HTx group, has 44 children who were critically ill and hospitalized before transplantation but without ventricular assist devices, whereas Group C, the VAD-HTx group, consists of 18 children resuscitated and supported with pulsatile pneumatic VADs for a median time of 20 days.

RESULTS

Overall actuarial survival after cardiac transplantation was 86% at 1 month, 82% at 1 year, and 78% at 5 years, without significant differences among the 3 sub-groups. Group A had the best long-term survival rate, 88% at 1 month, 88% at 1 year, and 80% at 5 years. Group B had a survival rate of 88% at 1 month, 82% at 1 year, and 79% at 5 years. Group C had a survival rate of 72% at 1 month, 72% at 1 year, and 72% at 5 years. We found no differences in neurologic outcome, acute cardiac rejection, or transplant failure. The survival rate was significantly better in the children with cardiomyopathy compared with those with congenital heart defects (p = 0.014).

CONCLUSIONS

Bridging to HTx with a pulsatile pneumatic VAD is a safe procedure in pediatric patients. After HTx, overall survival of these children is similar to that of patients who were bridged with inotropes or who were awaiting heart transplantation electively.

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.

LVAD bloodstream infections: therapeutic rationale for transplantation after LVAD infection

INTRODUCTION

Patients who have ventricular assist devices (VADs) and experience bloodstream infection (BSI) have high mortality. We addressed 2 questions raised by the United Network for Organ Sharing (UNOS) priority policy for this problem: 1) Are organs wasted on this ultra-high-risk group? 2) Can device-related BSI be differentiated from transient BSI?

METHODS

Patients with VADs who underwent heart transplantation from 1987 to 2001, who had BSI during VAD support, and who had positive cultures at VAD explant (device-related BSI, n = 10) were compared with those with negative cultures at explant (non-device-related BSI, n = 11).

RESULTS

Patients with device-related BSI had an 80% (8/10) rate of persistent bacteremia; 30 days and 1 year after transplantation, mortality was 14% and 26%, respectively. Non-device-related BSI (n = 11) persisted in 18% (2/11); peri-operative and 1-year mortalities were 9% and 13%. Duration of VAD support predicted infection (132 vs 48 days, p < 0.001); hypo-albuminemia (2.9 +/- 0.5 mg/dl vs 3.3 +/- 0.8 mg/dl, p < 0.05), and a resistant organism predicted a device-related BSI. These patients had increased intubation requirements and had increased creatinine concentration during the first post-operative week, with no difference in liver function, blood loss, transfusions (packed red blood cells, fresh frozen plasma, or platelets), or hemodynamic stability vs patients with non-device BSI. Despite decreased immunosuppression, we found no difference in acute rejection events with device-related BSI. Re-infection with the pre-operative organism occurred in only 1 patient per group.

CONCLUSIONS

These data suggest that urgent (Status 1A) cardiac transplantation is effective in stable patients with device-related BSI, and these data support the current UNOS policy. However, an extra-device source of BSI should be excluded by considering the isolated organism, the baseline nutritional status, and other risk factors.

Insertion of a left ventricular assist device in patients without thorough transplant evaluations: a worthwhile risk?

OBJECTIVES

Patients in acute cardiogenic shock may require placement of left ventricular assist devices before undergoing standard pretransplant evaluations. This practice raises ethical and logistic concerns and has led us to investigate the short- and long-term outcomes for this patient population. Methods and results We examined our adult bridge-to-transplant left ventricular assist device population over a 6-year period to characterize those patients with acute cardiogenic shock who received left ventricular assist devices on an emergency basis (ie, placement of a device within 24 hours of being listed for cardiac transplantation). Outcomes before and after transplant were compared with those of candidates with nonemergency evaluations by Kaplan-Meier survival curves and the Fisher exact test where appropriate. Of the 115 patients who required left ventricular assist device support, 73 (63%) patients required emergency placement; 70% of these patients survived to transplant compared with 83% of those with nonurgent device implantation (not statistically significant). Posttransplant survival curves were similar for patients with emergency device placement and those with nonurgent placement (not statistically significant). Twenty-two patients having emergency device placement did not undergo heart transplantation because of multisystem organ failure (14), device support withdrawal from irreversible neurologic injury (4), device or technical problems (2), and left ventricular assist device explant due to myocardial recovery (2).

CONCLUSIONS

At our institution, the majority of left ventricular assist devices are placed on an emergency basis. Few of these patients require discontinuation of device support due to undetected conditions during abbreviated preoperative evaluation. Survival before and after transplant is comparable with those of patients who undergo nonurgent left ventricular assist device placement or medical therapy.

Does the pretransplant UNOS status modify the short- and long-term cardiac transplant prognosis?

BACKGROUND

We compared the morbidity and mortality rates of patients who had urgent heart transplantation or transplantation after bridging with a ventricular assist device, with the rates of patients whose clinical stability allowed them to wait at home.

METHODS

From March 1985 to December 2000, 404 patients underwent heart transplantation in a single center. There were 273 patients with UNOS status 2 (US 2), 103 patients with UNOS Status 1A (US 1A), and 28 patients with UNOS Status 1B (US 1B). We compared the groups retrospectively with respect to pretransplantation status and operative results.

RESULTS

Despite more severely impaired hemodynamics and a significantly higher preoperative infection rate in US 1A and 1B patients, there were no statistically significant differences in survival rates among the three groups. Donor sex and age, cytomegalovirus and toxoplasmosis, mismatch rate, ischemic time, method of myocardial protection, and operative technique did not differ statistically among the three groups. Length of intensive care unit stay, postoperative morbidity, first year postoperative rejection rate, and graft occlusive vascular disease rate were statistically similar among the three groups. Although pretransplantation cancer assessment was less complete in US 1A and 1B than in US 2 patients, the late-cancer rate was not statistically different among the three groups.

CONCLUSIONS

These data suggest that urgently transplanted patients have both early and long term morbidity and mortality similar to those of patients waiting for transplantation at home or with a ventricular assist device.

Left ventricular assist device infections: three case reports and a review of the literature

Left ventricular assist device (LVAD) infections are a major device complication and are associated with significant morbidity. We report three cases of LVAD infections in our institution and review the literature to assess clinical parameters associated with infection, causative organisms, treatment modalities, and patient outcomes. A total of 46 cases were reviewed. Fever, leukocytosis, and drainage from the exit site were the most commonly reported symptoms. Left ventricular assist devices were in place an average of 65 days before the onset of infection. The most common site of LVAD infection was the drive line. Staphylococcus aureus was the most common organism, followed by gram negative rods, Candida, and enterococcus species and coagulase negative Staphylococcus. Treatment consisted primarily of surgical intervention, including incisional debridement, pump pocket exploration, and LVAD replacement and adjunctive intravenous antibiotics, especially vancomycin. Only eight infected patients died before transplantation, with five deaths due to sepsis. Four of these five patients were infected with a gram negative rod. In general, patients who developed an LVAD infection were able to undergo successful transplantation without recurrence, but infection with a gram negative rod was associated with a poor outcome.

Mechanical bridge with extracorporeal membrane oxygenation and ventricular assist device to heart transplantation

The aim of this study was to evaluate the effect of double bridges with extracorporeal membrane oxygenation (ECMO) and ventricular assist devices (VADs) in clinical heart transplantation. Between May 1994 and October 2000, 134 patients underwent heart transplantation at the National Taiwan University Hospital. Ten patients received ECMO or VAD support as bridges to transplantation. The ages ranged from 3 to 63 years. The indications included cardiac arrest under cardiopulmonary resuscitation in 2 and profound cardiogenic shock refractory to conventional therapy in 8 patients. Usually ECMO was first set up as rescue therapy. If ECMO could not be weaned off after short-term (usually 1 week) support, suitable VADs (HeartMate or Thoratec VAD) were implanted for medium-term or long-term support. Five patients received ECMO support as emergency rescue for 2 to 9 days, and then moved to Thoratec VAD for 8, 49, and 55 days, respectively, or centrifugal VAD for 31 days, or HeartMate VAD for 224 days. They all survived. The survival rate of double bridges with ECMO and VAD was 100%. In postcardiotomy cardiogenic shock, circulatory collapse from acute myocardial infarction or myocarditis, ECMO is the device of choice for short-term support. If heart transplantation is indicated, VADs should replace ECMO for their superiority as a bridge to heart transplantation. Our preliminary data of double bridges with ECMO and VAD revealed good results and were reliable and effective bridges to transplantation.

Pseudoaneurysm after heart transplantation with history of LVAD driveline infection

An infective complication of the aorta is a potential cause of early and late mortality after heart transplantation. We report the case of a 21-year-old male cardiac transplant patient in whom a pseudoaneurysm of the recipient site of ascending aorta coincided with the site of the outflow prosthesis of a preexisting left ventricular assist device; this condition developed 9 months after transplantation.

Ten-year follow-up of critically ill patients undergoing heart transplantation

BACKGROUND

The long-term result following heart transplantation appears very good despite complications of coronary atherosclerosis and cancer. Critically ill patients supported with mechanical devices remain a growing and difficult group in which long-term results need to be defined. The objective of this study was to review the 10-year follow-up of critically ill patients who underwent heart transplantation after support with mechanical devices.

METHODS

We retrospectively analyzed all patients who underwent heart transplantation from 1986 to 1999 at the Montreal Heart Institute.

RESULTS

Twenty-two patients (22/199, 11%) underwent heart transplantation after support with intra-aortic balloon pumps (n = 17) and total artificial hearts (n = 5). One hundred seventy-seven patients (177/199, 89%) underwent heart transplantation without pre-operative mechanical assistance. Patients with pre-operative mechanical assistance were younger (41 +/- 12 vs 48 +/- 10 years old, p = 0. 002), underwent a shorter waiting time to transplantation (2 +/- 2 vs 19 +/- 27 weeks, p = 0.004), and donor hearts had longer ischemic time (166 +/- 63 vs 137 +/- 49 minutes, p = 0.002) compared with patients without pre-operative mechanical assistance. One-month, 1-, 5-, and 10-year survival averaged 86% +/- 7%, 67% +/- 10%, 67% +/- 10%, and 59% +/- 12%, respectively, in patients with pre-operative mechanical assistance compared with 95% +/- 2%, 88% +/- 2%, 81% +/- 3%, and 74% +/- 4%, respectively, in patients without assistance, a significant difference (p = 0.04) that is mainly related to higher operative mortality in the former group. Although, we found no difference between the 2 groups in the 10-year freedom rate from acute rejection, infection, cancer, and coronary atherosclerosis, sepsis was the cause of 4 early deaths among patients with pre-operative mechanical assistance.

CONCLUSION

Early and long-term survival was significantly decreased in critically ill patients with pre-operative mechanical assistance compared with other patients without pre-operative assistance. Sepsis is a dominant threat among patients who underwent heart transplantation with pre-operative mechanical assistance, and the lower survival is due mainly to the increased early mortality.

Postcardiac surgery infections

Infections following cardiac surgery, although generally uncommon, are associated with difficult management decisions and significant morbidity and mortality. They often present while the patient is either in a critical care unit, or requires CCU management. This review analyzes infections related to median sternotomy wounds, prosthetic heart valves, transvenous permanent pacemakers, automatic implantable cardioverter-defibrillators, and left ventricular assist devices. The diagnosis, microbiology, treatment and outcome of each is also discussed.