Author + information
- Carl Lewis Backer, MD⁎ ()
- ↵⁎Reprint requests and correspondence:
Dr. Carl Lewis Backer, Children's Memorial Hospital, 2300 Children's Plaza, Box 22, Chicago, Illinois 60614-3363
In this issue of the Journal, Tissot et al. (1) from the Children's Hospital of Denver have presented the outcome of patients undergoing extracorporeal membrane oxygenation (ECMO) for early primary graft failure after pediatric heart transplantation. Nine percent of their patient population undergoing transplantation required post-operative ECMO support. Survival in this group was 54%. The long-term graft function of the patients supported with ECMO was similar to the overall transplant population. There are few situations more daunting for a pediatric heart transplant team than the patient who has difficulty being weaned from cardiopulmonary bypass after an apparently technically successful heart transplantation. One of the great joys of being a heart transplant surgeon is seeing the donor heart in normal sinus rhythm with excellent ventricular function by transesophageal echocardiography and an easy wean from cardiopulmonary bypass, chest closure, and a triumphant return to the intensive care unit of a previously very sick patient. Conversely, the donor heart that does not want to function, has arrhythmias, and clearly is not going to be weaned from cardiopulmonary bypass tends to deflate the operating room of its enthusiasm.
This series of patients undergoing post-operative ECMO therapy with a survival of >50%, and perhaps as important, a 100% 3-year survival in the surviving patients gives hope to surgical teams that are unable to wean a patient from cardiopulmonary bypass after a heart transplantation. The markers predictive of ECMO survival and the experience of this transplant group with >300 patients undergoing transplantation is a very good educational experience for any center in which pediatric heart transplantation is performed. I took away a number of points from this article and would like to highlight them in this editorial.
The total ischemic time of the donor heart has always been considered important for graft function and survival of the recipient. The total ischemic time in this series was significantly longer for ECMO-rescued recipients compared with the overall transplant population (276 ± 86 min vs. 204 ± 70 min, p < 0.01). This 30-min time difference, essentially 4 h vs. 4.5 h, appears to be critically important. This reminds all of us (i.e., the transplant procurement surgeon, the coordinators, and the flight team) that vigilance in the speed and efficiency of the procurement continues to be important. All possible anticipated delays should be addressed and focused to make the procurement as expeditious as possible. It is also an area that continues to await research that will improve donor preservation.
Hyperacute rejection was rare, with only 1 patient having this indication for ECMO support. The fact that only 1 of 28 children had hyperacute rejection, and presumably this is actually 1 of 310 total children transplanted, would indicate to me that in the current era of immunosuppression regimens this has become a very rare event. Because the outcome of hyperacute rejection is usually quite poor, the fact that it rarely happened is notable. In particular, the focus of the team when a donor heart is not able to support the recipient patient should probably be less on the risk or possibility of hyperacute rejection and more on other factors, including long donor ischemia time and possible donor issues before the harvest such as long “downtime,” high-dose pre-harvest inotropic support, and pre-operative anoxic insult to the heart (drowning, asphyxia, and so on).
The authors attempted to capture the characteristics of ECMO-rescued recipients. This step is important in that it helps the surgeon and transplant team to possibly prepare themselves for the child who may require post-operative ECMO support. The first risk factor was the longer total ischemia time, which I discussed previously. The next risk factor was younger age at the time of transplant, 1.3 years vs. 4.8 years (p = 0.002). This younger age goes along with the other factor, which is low weight at transplantation, 7.8 kg vs. 12.6 kg (p = 0.0001). The smaller, younger patients appear to be at greater risk of requiring ECMO support. That has certainly been the experience at our center. Factors that were not important for ECMO-rescued recipients included indications for transplantation (i.e., cardiomyopathy vs. congenital heart disease), the waiting time on the list (81 days vs. 77 days), and the donor-recipient weight ratio (1.9 vs. 1.8).
The authors evaluated patients who had neurological complications. These complications were found in 4 of 15 survivors. Two had permanent neurological impairment, and 2 had transient and resolved seizures. Of interest, all of the patients with neurologic disability were emergently cannulated in the cardiac intensive care unit, and 3 of these patients had cardiac arrest before cannulation. These outcomes give some credence to the thought that, with a 54% overall survival of patients on ECMO, earlier ECMO intervention rather than later ECMO intervention for the borderline patients may be important. Some centers are quite firm about not using high-dose inotropic support in these patients and go to early mechanical support, which will hopefully be a transient 24- to 48-h time of support. Clearly, the patient who has a cardiac arrest in the immediate perioperative period after heart transplantation is at greater risk of neurologic complications as noted by these authors.
One conclusion that the authors note but I am not sure whether I agree with is the time course of patients who are on ECMO support. In their series no survivor required ECMO support for >4 days. They note in the discussion that recovery of ventricular function with 8 days of ECMO support has been reported and may become more common as ECMO support technology progresses and improves over time. However, on the basis of their institutional experience, they recommend consideration be given to listing for retransplantation or transition to a ventricular assist device if the patient is not decannulated within 4 days of initiation of ECMO support. In our recent experience at our institution during the last 2 years we have had 3 children on post-operative ECMO support, all of whom were on ECMO support for over a week and all of whom are currently alive with their initial graft in place.
As the authors suggest, given the challenges of shortage of donors and the increased risk of transplantation after mechanical assistance, the decision to list for retransplantation should be reserved for those patients who are deemed to be good candidates for this option. Given our own personal experience I believe that, particularly for patients where the left ventricular function is preserved but it is a right ventricular issue with borderline pulmonary artery pressures and pulmonary vascular resistance issues, the use of ECMO for more than 4 days can still result in a successful outcome.
The results of this Denver series of ECMO requirement in 9% of the patients and an overall survival rate of 54% are not dissimilar from a recent abstract presented at the International Society of Heart and Lung Transplantation in Paris, France in April of 2009 (2). Dr. Groemmer and colleagues from Vienna, Austria reported that between the years 2000 and 2008, 59 (14%) of 425 patients required ECMO support after cardiac transplantation. The results of this series were that 75% of the patients could be weaned from ECMO, and in-hospital survival of these patients was 55%, which is nearly identical to the Denver experience. The duration of ECMO support was 5 ± 4 days. The survival has actually improved, and there appears to be an era effect, with the survival being only 20% between the years 2000 and 2003 and 50% in the years 2004 to 2008. The authors of this abstract concluded that ECMO is a valuable tool to overcome primary graft dysfunction after cardiac transplantation. It is interesting that the requirement for ECMO of 14% is very similar to the 9% in the Denver series and that the in-hospital survival of 55% was also nearly identical.
The paper by Tissot et al. (1) on the outcome of extracorporeal membrane oxygenation for early primary graft failure for pediatric heart transplantation describes a very interesting experience and one that should be of great interest to all centers performing pediatric heart transplants. The 54% survival rate in an extraordinarily complex group of patients is quite good, but remains a number that needs to be improved. In particular, the fact that all 15 children successfully weaned off ECMO were discharged alive and had a 100% 3-year survival is very encouraging. This series reminds us that the total ischemic time continues to be important and that hyperacute rejection is rarely a cause of primary graft failure in the immediate peritransplant time period. As mechanical support technology improves and progresses over time one would anticipate that the results of post-operative ECMO support would continue to improve. The other support mechanism that may be important in the future is mechanical ventricular assist devices, which continue to be miniaturized and improved and add to our post-transplant armamentarium.
↵⁎ Editorials published in the Journal of the American College of Cardiologyreflect the views of the authors and do not necessarily represent the views of JACCor the American College of Cardiology.
- American College of Cardiology Foundation
- Tissot C.,
- Buckvold S.,
- Phelps C.M.,
- et al.
- Groemmer M.,
- Mabar S.,
- et al.