Biventricular assist using a portable driver in combination with implanted devices: preliminary experience

Left ventricular assist systems with portable drive units are increasingly used in the clinical setting. However, such systems usually are not suitable for right ventricular support, and therefore, in the case of biventricular heart failure, they must be combined with other support devices that require additional drive consoles. As a result, most of the benefits of the wearable drive units (early mobilization and outpatient care) are lost. This present study was performed to evaluate biventricular support with implanted assist devices and a portable DC/battery-powered driver (Thoratec TLC-II). Electronic control by nonvolatile RAM accessible via RS232 interface, internal backup emergency battery, and optional manual activation are additional features of this 6 kg biventricular drive unit. In 3 bovine experiments (body weight 70 +/- 5 kg) partial cardiopulmonary bypass (CPB) was established, and two ventricular assist devices were implanted into a preperitoneal pocket on each side after connection to the right atrium and the pulmonary artery and to the left atrium and aorta, respectively. After weaning the patient from CPB, activated coagulation time (ACT) was kept at greater than 180 s, and biventricular support with the portable driver was activated. After 10 min, mean device flow stabilized at 3.5 +/- 0 L/min and remained at that level throughout the ensuing 6 h (3.5 +/- 0.3 L/min; NS). The heart rate moved from 130 +/- 13 beats per minute (bpm) at the end of CPB to 116 +/- 13 bpm after 10 min of assist (p < 0.05). Right atrial pressure moved from 11 +/- 2 mm Hg at the end of CPB to 13 +/- 3 mm Hg after 10 min of assist (not significant [NS]). Mean pulmonary artery pressure was 18 +/- mm Hg at the end of CPB and 17 +/- 5 mm Hg after 10 min of assist (NS). Left atrial pressure was 10 +/- 1 mm Hg at the end of CPB and 13 +/- 3 mm Hg after 10 min of assist (NS). Mean aortic pressure was 73 +/- 11 mm Hg at the end of CPB and 77 +/- 3 mm Hg after 10 min of assist (NS). Mixed venous oxygen saturation increased from 49 +/- 9% at the end of CPB to 58 +/- 10% after 10 min of assist (p < 0.05). The portable drive unit that was tested provides adequate power to maintain significant biventricular support with implanted right and left assist devices. The configuration of batteries tested driving two ventricles provides independence for 60 min.