Successful Bridge-to-Transplant of Functionally Univentricular Patients With a Modified Continuous-Flow Ventricular Assist Device.

A continuous flow extracorporeal ventricular assist device (VAD) was modified to support functionally univentricular infants and children awaiting heart transplantation. A centrifugal VAD, designed to flow from 1.5 to 8 L/min, was used as a bridge-to-transplant in four patients with functionally univentricular circulation. A variable restrictive recirculation shunt permitted lower flow ranges in small patients. In hypoxic patients, an oxygenator was incorporated into the circuit. From 2012 to 2015, the modified VAD was placed in four patients with Glenn physiology. Age ranged from 0.97 to 6.98 years (median = 2.2 yrs). Body surface area ranged from 0.41 to 0.84 m2 (median = 0.54 m2 ). One patient was on extracorporeal membrane oxygenation prior to VAD. A recirculation shunt was used in three patients. Three patients required temporary use of an oxygenator for 4, 10, and 27 days. Median time on the VAD was 32.3 days (range = 23-43 days). A decrease in the cavopulmonary pressure was noted in all patients, as was a fall in the B-type natriuretic peptide. Three patients survived transplant and were discharged at 28-82 days post-transplantation. One patient died after 35 days of support. Two patients experienced major bleeding events. Two patients experienced cerebrovascular accidents, one major and one minor. The centrifugal VAD successfully supported palliated functionally univentricular patients awaiting heart transplantation. The modified recirculation shunt facilitated the successful support of patients in whom optimal flows were substantially lower than that recommended by the manufacturer. The continuous-flow VAD effectively decompressed the cavopulmonary system. The design allowed placement of an in-line oxygenator in hypoxic patients. Further investigation is required to decrease the thromboembolic events, and associated morbidity, in patients supported with this device.

Novel Modifications of a Ventricular Assist Device for Infants and Children.

BACKGROUND: A continuous-flow "adult" ventricular assist device (VAD) was modified to support infants and children waiting for heart transplantation. METHODS: A centrifugal VAD, designed to flow at 1.5 to 8 L/min, was used as a bridge to transplantation in pediatric patients. In smaller children and infants, a modified recirculation shunt permitted lower flow ranges. In hypoxic patients, an oxygenator was spliced into the circuit. RESULTS: From 2010 to 2015, the VAD was placed in 13 consecutive patients. Age ranged from 0.9 to 16 years (median, 7 years). Body surface area (BSA) ranged from 0.4 to 2.1 m(2) (median, 0.8 m(2)). Ten patients had a BSA less than 1.0 m(2). Four patients were receiving extracorporeal membrane oxygenation (ECMO) before VAD. Three patients had single-ventricle physiology. Five patients had a recirculation shunt and 3 underwent insertion of an oxygenator. Median time on the VAD was 20 days (range, 2-140 days). In patients with a recirculation shunt, mean patient flow was 1.5 L/min (mean flow/BSA, 2.7 L/min/m(2)), with mean total VAD flow of 3.4 L/min. Twelve patients underwent transplantation, and 1 patient underwent VAD explantation. All patients survived and were discharged at a median of 26 days (range, 17-83 days) after transplantation. Three patients experienced major bleeding events. There were 2 cerebrovascular accidents. VAD mortality dropped from 33% (3 of 9) during 2007 to 2010 to 0% (0 of 13) between 2011 and 2015 (p = 0.05). Wait-list mortality dropped from 10% (5 of 52) to 4% (4 of 91) for these periods (p = 0.29). CONCLUSIONS: The centrifugal VAD successfully supported pediatric patients awaiting heart transplantation. The modified recirculation shunt facilitated the successful support of patients in whom optimal flows were substantially lower than those recommended by the manufacturer. The design allows placement of an in-line oxygenator. Compared with pulsatile devices, use of this VAD was associated with a trend toward decreased mortality associated with VAD use.

Modified TandemHeart ventricular assist device for infant and pediatric circulatory support.

PURPOSE: The development of pediatric ventricular assist device (VAD) circuits with lower flow ranges for infants and small children is ongoing. We present our results with modifying a readily available adult VAD to support the pediatric population. DESCRIPTION: The TandemHeart VAD (CardiacAssist, Pittsburgh, PA) circuit was modified to include a variable restrictive recirculation shunt to permit lower flow ranges in small pediatric patients. EVALUATION: Initial benchtop flow rates and pressures were studied. Hemolysis trials were performed using whole bovine blood to compare plasma-free hemoglobin levels between modified and unmodified VAD circuits. The modified VAD was surgically implanted in 7 piglets (6 to 14 kg) and which supported them for 4 hours. Levels of hemolysis did not increase and full hemodynamic support was achieved. The modified TandemHeart VAD with a recirculation shunt was subsequently implanted in 2 pediatric patients who were bridged to transplant successfully. CONCLUSIONS: Because of its simplicity, availability, low prime volume, greater patient flow range, and lower cost, the modified TandemHeart VAD with a recirculation shunt should be considered as an alternative to extracorporeal membrane oxygenation and other pulsatile VADs in children.

Successful Bridge to Transplant Using the TandemHeart(R) Left Ventricular Assist Device in a Pediatric Patient.

A nine-year-old girl ( 23 kg) was successfully bridged to heart transplantation with the TandemHeart(®) centrifugal pump for 10 days. Although this cardiac assist device has been used in adults for short-term mechanical support, its use in the pediatric population has not been widely reported. The TandemHeart(®) was easy to implant, achieved appropriate flows in this pediatric patient, and allowed for extubation and ambulation while awaiting a donor heart.

Optimizing circuit design using a remote-mounted perfusion system.

There is a considerable amount of literature published on the detrimental effects of banked blood exposure in cardiac surgery. Likewise, in an effort to minimize blood exposure, many of these articles involve modifications to the heart-lung machine or its components to reduce priming volumes, therefore decreasing the need for banked blood administration caused by hemodilution. In this study, using Terumo's System 1 Advanced Heart-Lung machine, all the pump heads were remotely mounted off the pump base closer to the patient and to all the pump components. For example, cardioplegia, ultrafiltration, and vent and cardiotomy lines are now close to the oxygenator and to the patient, minimizing any excess tubing length. Cardiopulmonary bypass (CPB) blood use and priming volumes were compared before and after changing from a fixed perfusion system to a remote-mounted perfusion system using the same disposables and protocols. The mean differences of pump prime and CPB blood use were compared in four weight classes. In the 8- to 12-kg class, blood use was reduced from 1.84 +/- 0.55 to 1.10 +/- 0.36 units. Priming volume was reduced from 751.2 +/- 68.4 to 360.4 +/- 51.7 mL. In the 13- to 20-kg class, blood use was reduced from 1.80 +/- 0.42 to 1.04 +/- 0.28 units. Priming volume was reduced from 829.6 +/- 69.6 to 476. +/- 81.4 mL. In the 21- to 40-kg class, blood use was reduced from 1.60 +/- 0.57 to 0.92 +/- 0.49 units. Priming volume was reduced from 994.0 +/- 137.2 to 713.6 +/- 121.8 mL. In the 41+-kg class, blood use was reduced from 1.62 +/- 0.88 to 0.42 +/- 0.54 units. Priming volume reduced from 1306.3 +/- 112.9 to 875.5 +/- 96.6 mL. In conclusion, using a remote-mounted perfusion system resulted in reducing priming volumes and also significantly decreased the need for banked blood, subsequently saving the patient excessive exposure to banked blood.