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Ann Thorac Surg 2004;77:2096-2102
© 2004 The Society of Thoracic Surgeons

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Original article: cardiovascular

Changing donor and recipient demographics in a heart transplantation program: influence on early outcome

^a Cardiothoracic Surgery, Auckland, New Zealand
^b Department of Cardiology, Green Lane Hospital, Auckland, New Zealand

Accepted for publication September 5, 2003.

^* Address reprint requests to Dr Ruygrok, Department of Cardiology, Green Lane Hospital, Private Bag 92189, Auckland 1030, New Zealand
e-mail: pruygrok{at}adhb.govt.nz

	Abstract

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 
BACKGROUND: The purpose of this study was to investigate whether broadening acceptance criteria for donor hearts and changing recipient demographics resulted in an increased perioperative morbidity and mortality in a heart transplant program.

METHODS: Donor and recipient data of 137 consecutive heart transplants performed from 1987 to 2001 were retrospectively analyzed and divided into three equal eras, each of 5 years: 1987 to 1991, 1992 to 1996, and 1997 to 2001. Multivariate analyses of recipient and donor demographics and operative factors were performed to identify the predictors of low cardiac output, intraaortic balloon pump utilization, 30-day mortality, and duration of intensive care and hospital stay.

RESULTS: Significant increases in number of female recipients (p = 0.025), cardiopulmonary bypass (p < 0.001), recipient cross-clamp (p < 0.001), donor age (p = 0.009), donor ischemic times (p < 0.001), use of cardioplegia (p < 0.001) and the bicaval technique (p < 0.001), brain death to retrieval time (p = 0.006), and need for postoperative dialysis were observed for the three study periods, whereas length of intensive care and hospital stay decreased. Female donor (odds ratio [OR], 2.4; 95% confidence interval [CI], 1.0 to 5.7) was identified as a risk factor for low cardiac output. Female donor (OR, 3.7; 95% CI, 1.3 to 10.7), donor cardiac arrest (OR, 6.4; 95% CI, 1.6 to 25.9), and cardiopulmonary bypass time more than 2 hours (OR, 7.6; 95% CI, 2.1 to 28.1) were associated with increased intraaortic balloon pump utilization. Intensive care stay was prolonged by the biatrial technique (OR, 3.9; 95% CI, 1.3 to 11.9) and reduced by the use of cardioplegia (OR, 0.3; 95% CI, 0.1 to 0.9), longer cardiopulmonary bypass (OR, 0.2; 95% CI, 0.1 to 0.6) and aortic cross-clamp times (OR, 0.1; 95% CI, 0.03 to 0.6).

CONCLUSIONS: Although a number of significant changes were observed during the study period, no donor, recipient, or operative factors influenced 30-day mortality. This study justifies our current donor and recipient selection policies.

	Introduction

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Heart transplantation remains an important but limited treatment modality for selected patients with end-stage heart failure. Increasing waiting lists, a result of broadening of acceptance criteria, and a shortage of donor hearts worldwide have resulted in the acceptance of so-called marginal donors who may be older, be hemodynamically less stable, and have longer ischemic times [1–7]. The aim of our study was to establish whether liberalization of recipient and donor selection policies at our institution have impacted significantly on early outcome after cardiac transplantation and to attempt to identify any predictors of adverse outcome.

	Material and methods

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Data collection
Donor, recipient, and operative data were retrospectively collected on all 137 consecutive heart transplant operations performed at Green Lane Hospital, the sole cardiac transplant unit in New Zealand (population 4 million), from the inception of the program in December 1987 to December 2001. As New Zealand consists of islands and is geographically isolated (with respect to ischemic time, flight time to our nearest neighbor, Australia, is 3.5 hours), all heart transplants were performed on New Zealand citizens with donor organs from within the country. Most recipients were United Network for Organ Sharing status II, and a small number were status IB. No recipients had been on ventricular assist devices before transplantation.

Approximately 10 to 20 suitable donor calls per annum were received, with a similar number of potential recipients on our waiting list. After a prospective T-cell crossmatch and an echocardiogram, the potential donor was matched initially with recipients of the same blood group (O to O, A to A, and so forth) and then for weight, with a donor to recipient weight ratio of no less than 0.8. The recipient was then finally chosen from the remaining candidates on the basis of urgency.

Surgical technique
Nine different surgeons using either the biatrial or bicaval surgical technique, depending on their preference, performed the cardiac transplants. The biatrial and bicaval techniques have previously been described by Lower and associates [8] and Blanche and colleagues [9], respectively. The method of myocardial protection for those who received it evolved during the study period from crystalloid to blood cardioplegia administered either antegradely or retrogradely into the donor heart at the time of implantation. The method of cardioplegia varied greatly from surgeon to surgeon and evolved during the study period. All surgeons now use substrate-enriched blood cardioplegia (hot-shot) before aortic cross-clamp release, although most surgeons also administer cold substrate-enriched cardioplegia after completion of the left and right atrial or bicaval anastomoses. St. Thomas's solution was the preferred donor heart preservation solution.

Immunosuppression
Patients were treated with perioperative methylprednisolone and antithymocyte globulin before commencing triple therapy with cyclosporin, azathioprine, and prednisone. In October 1998 routine induction therapy was removed from our protocol. During the last decade our immunosuppressive armamentarium has widened with the availability of tacrolimus, mycophenolate mofetil, and more recently sirolimus for patients with recurrent episodes of rejection or those experiencing significant side effects to our standard immunosuppressive agents.

Definitions
A donor was defined as being on inotropic agents if dopamine or similar inotropic agents had been commenced before or at the time of retrieval. Vasoconstrictors such as noradrenaline and Aramine (metaraminol tartrate) were not considered inotropic agents for the purpose of our review. Donor cardiac arrest was any witnessed ventricular fibrillation or asystole before retrieval. Donor death to retrieval time was the time interval between confirmed brain death, after second brain death testing, to application of the cross-clamp to the donor aorta. Recipient cross-clamp time was defined as the time interval between application of the cross-clamp to the recipient aorta and removal. Low cardiac output (LCO) was defined as a requirement for dopamine at more than 5 µg · kg^–1 · min^–1 or another inotropic agent at equivalent dosage. Insertion of an intraaortic balloon pump (IABP) was considered a more objective indicator of LCO. Perioperative death was defined as any death that occurred within 30 days of transplantation. The duration of intensive care unit (ICU) stay was defined as the time from transplantation until the first transfer to the medium-care ward and hospital stay until first discharge from hospital to the within hospital grounds, motel-type facility.

Variables studied
Recipient, donor, surgical, and outcome data for the period 1987 to 2001 were tabulated. The study period was further subdivided into three eras, each of 5 years: 1987 to 1991, 1992 to 1996, and 1996 to 2001, to attempt to identify any temporal changes. Multivariate analyses of recipient and donor demographics and operative factors were performed to identify predictors of LCO, IABP insertion, prolonged ICU and hospital stay, and 30-day mortality. The recipient, surgical, and donor variables tested are listed in the Appendix.

Statistical analysis
Results are reported as counts (percentage), averages ± standard deviation, or median (interquartile range) if more appropriate. Normality was assessed visually with plots (box and whisker and q-q plots) and with the Shapiro-Wilk test. To investigate differences as a function of time, the study period was divided into three eras, and analysis of variance or, when more appropriate, the nonparametric test Kruskal-Wallis rank analysis of variance was used to assess statistical significance. Trend lines were estimated using the scatterplot smoother lowess command [10]. Associations between outcomes and risk factors were investigated using logistic regression, and results were reported as odds ratios with 95% confidence intervals. For ease of interpretation, continuous risk factors in the models were expressed using categorical classifications, which were made at clinically meaningful cuts or, if not available or relevant, the upper quartile. A p value of less than 0.05 was considered statistically significant. The statistical software package S-Plus (Mathsoft Inc, Seattle, WA) was used to generate all figures and SAS release 8.0 (SAS Institute Inc, Cary, NC) was used for all remaining analyses.

	Results

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Changes in demographics
The recipient, donor, and surgical profiles are displayed in Table 1. Seven (5%) recipients were 60 years of age or older, and all received transplants in the last 2 years of the study. The cause of end-stage heart failure was dilated cardiomyopathy in 49%, ischemic cardiomyopathy in 34%, valvular heart disease in 8%, congenital heart disease in 4%, and other causes in 5% of patients. During the period 1987 to 1996, all transplants were performed using the biatrial technique, and since 1997, in 37 of 62 (59%) transplants the bicaval technique was used. Figure 1 demonstrates that recipient age, cardiopulmonary bypass time, recipient cross-clamp time, donor age, and donor ischemic time all increased with time, particularly since 1997. Table 1 demonstrates that recipient age, number of recipients with previous median sternotomy, mean pulmonary vascular resistance and transpulmonary gradient, preoperative creatinine, female donor, and distance traveled to procure donor organs have not shown significant increases during the three eras, whereas number of female recipients, donor ischemic and cardiopulmonary bypass times, death to organ retrieval time, mean donor age, use of the bicaval technique, and cardioplegia and recipient cross-clamp times have all increased significantly. When assessing outcomes, the durations of ICU and hospital stay have decreased significantly as a function of time. Although there was a significant increase in the need for postoperative dialysis, and a trend to an increased requirement for IABP insertion, there was no difference in the number of recipients considered to be in a low-output state postoperatively, to need reexploration for bleeding, and to have a requirement for permanent pacing. There was no difference in 30-day mortality among the three eras.

View larger version (26K): [in this window] [in a new window]   Fig 1. Demographic trends during study period. (A) Recipient age; (B) bypass time; (C) recipient cross-clamp time; (D) donor age; (E) donor ischemia time. The circles represent individual data points and the lines join the mean values.

Predictors of adverse outcomes
The associations between possible risk factors and adverse outcomes are displayed in Table 2. Female donor was identified as a risk factor for LCO, and female donor, donor cardiac arrest, and cardiopulmonary bypass time more than 2 hours was identified as a risk factor for the requirement for IABP utilization. The biatrial technique was associated with prolonged ICU stay. The use of cardioplegia resulted in a reduction in ICU stay, but paradoxically cardiopulmonary bypass time more than 2 hours and aortic cross-clamp time more than 100 minutes appeared to reduce ICU stay.

	Comment

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Recipient age has been steadily increasing in our series with 7 of the last 29 recipients being 60 years of age or older; however, neither recipient age more than 50 years nor recipient sex predisposed an increased 30-day mortality. Others have similarly found that recipient age (>50 years), diagnosis, and sex were not risk factors for perioperative mortality, and that well-selected elderly recipients yielded clinical results similar to those of younger patients [11–13].

Our study also found that a significant increase in donor age, a trend that has been reported worldwide [1], was not associated with an increase in adverse outcomes. Although several studies have found that hearts from donors older than 50 years of age provide a long-term survival similar to that from younger donors [2, 3], other series have shown donor age of 50 years or greater to be a risk factor for operative mortality and decreased long-term survival and recommend that, in these cases, ischemic time should be minimized and implantation in an older recipient should be considered [11]. Coronary angiography of hearts from older donors has been proposed to expand the donor pool without the concomitant increased risk of transferring coronary artery disease from donor to recipient. The sole predictor of detecting coronary artery disease was increasing donor age (>45 years) [14]. As well as accepting older donor hearts, means suggested for widening the donor pool have included the acceptance of nonbeating heart donors, longer ischemic times, donors with systemic infection or those who are hepatitis positive or have prolonged hypotension, undersized hearts, hearts with conduction abnormalities, prior cardiac arrest, high-dose intravenous catecholamines, moderately depressed left ventricular function, and even supporting donors on cardiopulmonary bypass assuming that myocardial dysfunction was secondary to brain death [4, 15].

In an international survey of 164 centers, the majority of donor ischemic times were between 300 and 400 minutes with no difference in maximum acceptable ischemic time between European (mean, 5.9 hours) and American centers (mean, 5.7 hours). More than 20% of centers accept ischemic times of up to 7 hours [16]. Marelli and associates [13] concluded that longer donor ischemic time and older donor age influence survival but are of low clinical significance. Donor ischemic times in our series are shorter (mean, 214 minutes [3.5 hours]; range, 89 to 465 minutes) but have increased significantly during the study period of 15 years and since 1999, were more than 6 hours in 5 transplants, of which one was more than 7 hours. We found ischemic time was significantly longer in recipients receiving a bicaval anastomosis and in those who received cardioplegia, both of which became more frequent during the study period, which may partly explain this observation. Other possible contributing factors may be the expansion of our pool of transplant surgeons, some of whom may only perform two or three transplants per year, and a lessening sense of urgency during the retrieval process. As our cardiac hospital has no general ICU, all donors were from other hospitals. The mean retrieval distance increased, indicating that ICUs farther afield were supplying more donors with resultant travel to more-isolated hospitals and longer flight times.

Female donor was a statistically significant risk factor for LCO and IABP insertion, but multivariate analysis failed to demonstrate this as a risk factor for mortality. Female donor has been identified as a risk factor in other studies [11, 17], but Brock and coworkers [5] demonstrated that donor factors such as age and sex did not affect 30-day mortality, similar to our findings. Donor cardiac arrest predicted IABP insertion but not mortality in our study. Donor cardiac arrest has not been a contraindication to utilization in other centers [18]. Although there has been an increasing IABP utilization in our series, there has also been a lowered threshold for balloon insertion.

Our experience suggests that pulmonary vascular resistance more than 3 Wood units and transpulmonary gradient more than 10 mm Hg are not significant risk factors for LCO, IABP utilization, or mortality. Delgrado and colleagues [19] found that transpulmonary gradient, pulmonary vascular resistance, and pulmonary vascular resistance index were significantly associated with mortality on univariate analysis, but on multivariate analysis, only the latter was an independent predictor. Although the preoperative creatinines were similar in our three groups of patients, there was a significant increase in the requirement for temporary postoperative dialysis. This is likely related to elimination of antithymocyte globulin from our immunosuppressive protocol in 1998 and the resultant earlier and more aggressive introduction of cyclosporine after surgery.

The time interval between brain death and retrieval has increased significantly during the study period. Bittner and associates [20] suggested that risk of right ventricular failure is more a result of the effects of brain death than high pulmonary vascular resistance. Depression of biventricular cardiac function occurs within 4 hours of brain death in dogs [21] owing to various vasomotor and hormonal changes (sympathetic storm) and acute endocrine collapse that occur at brain death [22]. The choice of surgical technique was not an independent risk factor for mortality in our experience. Grande and coworkers [23] and Milano and associates [24] reported similar findings. Administration of blood cardioplegia during surgical implantation may be a useful adjunct [6] but was not universally used by surgeons in our unit. Cardioplegia of the donor heart resulted in a shortened length of ICU stay. Paradoxically, increased bypass and aortic cross-clamp times were also found to reduce ICU stay. We find these observations difficult to explain, but these increased times may be more than offset by beneficial effects of cardioplegia and the bicaval anastomosis (which we found to be significantly time-consuming), as they had no influence on the total length of hospital stay. The hospital stay in our series was relatively short, possibly because of an intermediate self-care facility on the hospital grounds to which our patients were discharged, which may not have been the case in other studies [25–27].

Figure 2 demonstrates the long-term survival of patients transplanted at Green Lane Hospital during the three eras, which compares favorably with the international registry data [1]. Our results are encouraging considering that low-volume centers (our center performs 10 to 15 transplants annually) have been shown to have a higher 1-year mortality than higher volume centers [1].

View larger version (19K): [in this window] [in a new window]   Fig 2. Kaplan-Meier survival curve stratified by era: 1987 to 1991 (– –); 1992 to 1996 (– ); 1997 to 2001 (—), with numbers at risk.

	Acknowledgments

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 
The authors wish to express their gratitude to John Beca, Clinical Director of the Intensive Care Unit, Tim Wilcox, Director of Clinical Perfusion, and Helen Gibbs, Transplant Recipient Coordinator, Green Lane Hospital, for their invaluable assistance with this study. The authors dedicate this paper to all those surgeons, cardiologists, anesthetists, perfusionists, intensivists, transplant coordinators, and theater and postoperative nursing staff who spent many sleepless nights transplanting these terminally ill patients.

	Appendix

 
Recipient factors
Age more than 50 years

Female recipient

Previous surgery

Pulmonary vascular resistance more than 3 Wood units (before vasodilator challenge)

Transpulmonary gradient more than 10 mm Hg

Surgical factors
Biatrial technique

Bicaval technique

Cardioplegia

Cardiopulmonary bypass time more than 2 hours

Aortic cross-clamp time more than 100 minutes

Donor factors
Donor age more than 50 years

Female donor

Donor cardiac arrest

Donor ischemic time more than 5 hours

Time between brain death to retrieval time more than 682 minutes

Distance to donor hospital more than 660 km

	References

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 

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