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Heart Transplantation in Children after Mechanical Circulatory Support: Comparison of Heart Transplantation with Ventricular Assist Devices and Elective Heart Transplantation

Coskun, Oguz; Parsa, A; Weitkemper, H; Blanz, U; Coskun, T; Sandica, E; Tenderich, G; El-Banayosy, A; Minami, K; Körfer, R

doi: 10.1097/01.mat.0000174630.23368.18
Clinical Outcomes-Devices

Heart transplantation (HTx) is an ultimate treatment for children with end-stage heart failure or inoperable congenital heart disease. The supply of hearts is inadequate; therefore, different mechanical support systems must be used as bridge to HTx in pediatric patients with postoperative low output. The use of ventricular assist devices (VADs) as bridge to HTx in children is limited because of size differences. The purpose of this study was to evaluate the overall long-term outcome of pediatric circulatory support before pediatric HTx. From 1989 through 2004, 91 pediatric patients underwent isolated HTx. Seven of them required mechanical support before transplantation. We reviewed retrospectively the course of 91 children (mean age 14.7 years) who underwent HTx. Group A consisted of elective HTx patients who were treated as outpatients before HTx, whereas group B was the VAD-HTx bridging group (n = 7; mean age 12.31 ± 2.8 years). Mean duration of VAD support was 108 ± 98 days (minimum 1 day, maximum 258 days). Overall survival rate after HTx was 80% at 1 year without significant differences between groups. Five of seven patients survived and could be discharged after successful HTx, for a survival rate of 77%. The mean follow-up period was 16.76 ± 10.6 months. No differences in posttransplantation long-term survival and rejection episodes occurred between patients transplanted with or without VAD. VAD therapy can keep pediatric patients with end-stage heart failure alive until successful HTx, and bridge to HTx is a safe procedure in pediatric patients. After HTx, survival rates of these children are similar to those of patients awaiting elective HTx.

From the Heart-Center of North-Rhine Westphalia, Department of Cardiovascular Surgery, Bad Oeynhausen Germany.

Submitted for consideration and accepted in revised form May 2005.

Presented in part at the First International Conference on Pediatric Mechanical Circulatory Support Systems and Pediatric Cardiopulmonary Perfusion, May 19–22, Hershey, PA, USA.

Reprint Requests: Oguz Coskun, Heart-Center of North-Rhine Westphalia, Department of Cardiovascular Surgery, Georg-Str. 11, D-32545 Bad Oeynhausen Germany

Heart transplantation (HTx) is the ultimate treatment for end-stage heart disease for adults and children, including ne-onates and pediatrics. Since Kantrowitz and colleagues'1 first HTx in infants in 1968 and Cooley and colleagues'2 first bridge to HTx in 1969, various mechanical circulatory support systems have been developed and used all over the world; nevertheless, the limitations are still the same, particularly, suitable sizes for pediatrics. Because of the shortage of donor organs, mechanical circulatory support is still the only alternative to bridge these patients to HTx. Compared with the systems used in adult cases, the selection of ventricular assist device (VAD) systems for adequate support for children is limited.

A number of devices have been developed to defeat these limitations. Some of the pioneers in this field are Del Nido et al.,3 who bridged to HTx by extracorporeal membrane oxygenation in 1985; Frazier et al.,4 who bridged to HTx in 1989 by a Biomedicus centrifugal pump; and Warnecke et al.,5 who did it with the Berlin Heart System in 1991.

The purpose of this study was to evaluate the overall outcome of transplanted pediatric patients after circulatory support.

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Materials and Methods

We retrospectively analyzed 91 pediatric patients who underwent HTx from 1989 to 2004. Seven of these patients required support by a VAD system before HTx. Group A comprised 84 pediatric patients who underwent HTx electively as outpatients, whereas group B comprised 7 pediatric patients who were supported with VAD systems before HTx as a consequence of low-output or postcardiotomy syndrome after corrective congenital operations. Table 1 shows demographic data including age, weight, height, and diagnoses for all patients in group B.

The aim of VAD support was maintenance of systemic circulation, recovery of multiple organ failure, and bridge to transplantation. Criteria for receiving VAD support were clinical deterioration (despite optimal pharmacologic support and the use of an intraaortic balloon pump), low-output syndrome, mean arterial pressure <60 mm Hg, ejection fraction <25%, cardiac index <2 l/min, diuresis <1 ml/min/kg, central venous pressure >15 mm Hg, and left atrial pressure >18 mm Hg.

Routine evaluation of ejection fraction via echocardiography within 72 hours showed an improvement or an irreversible organ failure, so that we evaluated the patients according to HTx selection criteria to place them on the waiting list. HTx selection criteria were irreversible heart pathology, stability of major organ function, no neurologic defects, no active infection/sepsis, and family and social compliance. Normally, clinical improvement is seen immediately after VAD implantation. We achieved a sufficient circulation, preventing multiorgan failure by normalizing organ perfusion to wean off inotropes. Table 2 shows device type, indications for VAD, duration of support, and survival in group B.

The VAD systems used in our cohort were the Biomedicus centrifugal pump, Thoratec or Medos paracorporeal systems, and the Novacor LVAD. For short-term support up to 6 weeks, we used the Biomedicus centrifugal pump consisting of the pediatric pumphead (35 ml) and a 0.25-inch tubing set. Usually, this system is used for bridge to recovery or bridge to bridge.

We prefer Thoratec and Medos devices, especially for midterm support up to 1 month, and the Novacor device for long-term use (>6 months) if body surface area (BSA) is more than >1.5 m2. For a BSA of less than 1.5 m22 in pediatric cases, we prefer the Medos system because of its miniaturized chambers with various sizes from 10, 25, and 60 ml for the left side chamber and 9, 22.5, and 54 ml for the right side chamber. It can even be used in neonates with a BSA <0.3 m2. Figure 2 shows device variations of Medos. Thoratec can be used for patients with a body weight >40kg, especially in cases of biventricular heart failure.6 We found that the device-related patient selections are important for both the outcome and the duration of support.

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Results

Of the 91 patients, 75 survived transplantation. The overall mean survival rate was 82%. There were no significant differences in survival rates between groups. Actuarial survival in group A was 91% at 1 year, 88% at 5 years, and 84% at 10 years. Actuarial survival in group B was 71% at 1 year, 71% at 5 years, and 71% at 10 years. Figure 3 shows cumulative survival analysis of the groups as Kaplan-Meier survival function. Major complications were bleeding, thrombosis, and infection. There are no neurologic disorders in Group B survivors. No renal dysfunction was seen in either group.

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Discussion

Candidates for VADs are patients with postcardiotomy low-output syndrome, acute heart failure, and those on the waiting list who show deterioration in clinical condition despite maximum pharmacologic support. Organ shortage is the main cause of death for patients on the waiting list.

With VADs, patients can be bridged for weeks or months, so that they have the chance to receive a suitable organ. The average waiting time on the list of 304 days has not decreased since 1998,6 and the mortality rate, which is now up to 30%7 of those on the waiting list, can only be decreased with VADs.

End-organ recovery is the second major advantage in addition to VAD's lifesaving and time-gain functions. Satisfactory long-term survivals are associated with end-organ recovery, which is achieved before HTx. Duncan8 demonstrated that in-hospital survival rates of 40–80% are possible for children who require mechanical support, and described a border time interval of support of 72 hours for extracorporeal membrane oxygenation and 48 hours for VAD in which recovery of ventricle function must occur; otherwise, patients require HTx.9 Comparing our results with those of Pasic et al.10 and Stiller et al.,11 who reported 1-year survival rates of 62% and 82%, respectively, our survival rates are acceptable.

Although neurologic complications are one of the major causes of morbidity during VAD support, successful management of anticoagulation can decrease the incidence of adverse events.

According to Reiss et al.,12 renal dysfunction is a predictor of high mortality in VAD patients, which emphasizes the importance of implantation timing. Early referral and elective implant result in better outcomes with regard to end-organ recovery.

Our results are comparable with those of other centers, and the best results seem to be related to end-organ recovery achieved with the correct VAD selection and implantation timing.

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References

1. Kantrowitz A, Haller JD, Joos H, et al: Transplantation of the heart in an infant and an adult. Am J Cardiol 22: 782–790, 1968.
2. Cooley DA, Hallman GL, Bloodwell RD, et al: First human implantation of a cardiac prosthesis for staged total replacement of the heart. Trans Am Soc Artif Intern Organs 15: 252–266, 1969.
3. Del Nido PJ, Armitage JM, Fricker FJ, et al: Extracorporal membrane oxygenation support as a bridge to pediatric heart transplantation. Circulation 90: 66–69, 1994.
4. Frazier OH, Bricker JT, Macris MP, Cooley DA: Use of a left ventricular assist device as a bridge to transplantation in a pediatric patient. Tex Heart Inst J 16: 45–50, 1989.
5. Warnecke H, Berdjis F, Hennig E, et al: Mechanical left ventricular support as a bridge to cardiac transplantation in childhood. Eur J Cardiothorac Surg 5: 330–333, 1991.
6. Minami K, El-Banayosy A, Sezai A, et al: Morbidity and outcome after mechanical ventricular support using Thoratec, Novacor, and Heartmate for bridging to heart transplantation. Artif Organs 24: 421–426, 2000.
7. Vitali E, Lanfranconi M, Ribera E, et al: Successful experience in bridging patients to heart transplantation with the MicroMed DeBakey ventricular assist device. Ann Thorac Surg 75: 1200–1204, 2003.
8. Duncan BW: Mechanical circulatory support for infants and children with cardiac disease. Ann Thorac Surg 73: 1670–1677, 2002.
9. Duncan BW, Hraska V, et al: Mechanical circulatory support in children with cardiac disease. J Thorac Cardiovasc Surg 117: 529–542, 1999.
10. Pasic M, Loebe M, Hummel M, et al: Heart transplantation: A single-center experience. Ann Thorac Surg 62: 1685–1690, 1996.
11. Stiller B, Hetzer R, Weng Y, et al: Heart transplantation in children after mechanical circulatory support with pulsatile pneumatic assist device. J Heart Lung Transplant 22: 1201–1208, 2003.
12. Reiss N, El-Banayosy A, Arusoglu L, et al: Recovery of organ dysfunction during bridging to heart transplantation in children and adolescents. Int J Artif Organs 26: 395–400, 2003.

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