Use of the TandemHeart® left ventricular assist device as a bridge to transplant in a 6-year-old with dilated cardiomyopathy

By Yuriy Slota, MD; Premal M. Trivedi, MD
Ann & Robert H. Lurie Children’s Hospital of Chicago
Northwestern University Feinberg School of Medicine
Chicago, IL

Introduction
Prior to the past decade, extracorporeal membrane oxygenation (ECMO) represented the primary means for pediatric mechanical circulatory support (MCS), regardless of the duration of support that was needed.1 Recently, however, there has been an increase in the number as well as types of support available to children, mainly in the form of pulsatile and centrifugal ventricular assist devices (VADs). Despite the increasing prevalence and use of these devices, further experience remains necessary to determine those devices that best address the needs of patients requiring MCS.

To that end, the TandemHeart® ventricular assist device was used in the patient presented here in irreversible heart failure. While there has been significant experience with the TandemHeart® in adults as a short-term device2, the pediatric experience has been more limited. This case demonstrates the potential to use this device in small children not only as a bridge to recovery, but also to transplantation.

Case Report
A 6-year-old girl (17.9 kg) who was previously healthy presented in congestive heart failure with profound left ventricular dilation and severely depressed biventricular function. Given the absence of an infectious, metabolic, muscular, or inflammatory etiology for her failure and a positive family history for cardiomyopathy, the patient was presumed to have a familial dilated cardiomyopathy and was subsequently listed for transplant.

The patient was initially stabilized with a regimen of diuresis and inodilation with milrinone. Several days later she decompensated, requiring intubation and an increase in her inotropic support. As her markers for end-organ perfusion worsened from their previously normal state, including her mixed venous saturation, lactate, and creatinine, the patient was put forth for MCS with the TandemHeart® left ventricular assist device (LVAD, CardiacAssist, Inc., Pittsburgh, Pennsylvania).

Given the patient’s hemodynamic instability, the LVAD was placed with the patient on cardiopulmonary bypass. Venous inflow into the TandemHeart® was achieved via cannulation of the left atrial dome and arterial outflow was secured via a graft sewn to the ascending aorta (Fig. 1).3 Both cannulas were tunneled through separate incisions inferior to the sternotomy and connected to the TandemHeart® pump (Fig. 2). The patient was slowly weaned from bypass and transitioned to the LVAD on epinephrine, norepinephrine, and inhaled nitric oxide for right heart support. Flows of 1.8-2.2 liters/minute for a calculated cardiac index of 2.5-3 liters/minute/meter2 were ultimately reached at 4500 revolutions per minute (RPMs). Transesophageal echocardiography demonstrated good left atrial drainage and moderately depressed right ventricular function without dilation.

Post-operatively, the patient’s biomarkers slowly normalized and her inotropic support was weaned to only milrinone. Flows of 2-2.2 liters/minute were maintained without any significant increases in RPMs. Because of intermittent fevers, the patient was kept intubated and sedated in order to decrease oxygen consumption. On post-operative day 8, a donor heart became available. She underwent successful heart transplantation and is now home and doing well. No device or cannula thrombi were noted at the time of explant.

Discussion
The use of VADs in the pediatric population has grown exponentially in recent years.4 This has been attributable to the miniaturization and improvement in the devices available, as well as the increasing number of pediatric patients being hospitalized with heart failure.1 Given the limitations in the availability of donor hearts and the related unpredictability of wait-times, the management of end-stage heart failure in children appears to be increasingly dependent on the development of multiple durable options for MCS.

The TandemHeart®, as presented here, may represent a viable option in providing short- and perhaps even long-term support in small and large children. This VAD is a centrifugal, continuous-flow, extracorporeal pump that may be implanted centrally, as in this patient, or percutaneously via the femoral vessels in larger patients (Fig 3). A concern in using this device in infants and small children is its ability to generate appropriate flows in its RPM range of 3500-7500.5 Though this issue certainly needs further study, it appears that adequate flows may be achievable by using smaller inflow and outflow cannulas.3

Advantages of centrifugal pumps like the TandemHeart® include its simplicity, ease of implant, reduced risk of blood trauma, and potential for lower complication rates relative to ECMO or pulsatile VADs.6 And like other devices currently used, it can also allow for extubation and ambulation while awaiting transplantation if centrally placed. As more experience is gained with both pulsatile and centrifugal devices in the pediatric population, comparative studies will be necessary to determine relative survival outcomes and complication rates.

Declaration of Conflicting Interests and Funding
The authors have no conflicts of interest to reveal and received no funding for this manuscript.

References

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