Clinical experience with an implantable, intracardiac, continuous flow circulatory support device: physiologic implications and their relationship to patient selection

Background We have been investigating continuous-flow circulatory support devices for 20 years. Unlike pulsatile assist devices, continuous-flow pumps have a simplified pumping mechanism and they do not require compliance chambers or valves. In the 1980s, clinical experience with the Hemopump proved a high-speed, intravascular, continuous-flow pump could safely augment the circulation. Subsequently, a decade of animal experiments with a larger, longer-term continuous-flow pump (the Jarvik 2000) confirmed the safety and efficacy of intraventricular placement, leading to its clinical application. Methods We analyzed the physiologic and anatomic effect of using the Jarvik 2000 pump for cardiac support in 23 patients in whom the device was applied as a bridge to transplant under the protocol approved by the Food and Drug Administration Investigational Device Exemption. The device was used as a bridge to transplantation in 20 patients and as destination therapy in 3 patients. Results In the bridge-to-transplant group, 14 patients underwent transplantation, 5 died during the circulatory support period and 1 is in an ongoing study. The support period lasted an average of 90 days. For the survivors, the follow-up period has averaged 16 months. Within the first 48 postoperative hours, the average cardiac index increased by 65% (from 1.77 ± 0.24 to 2.92 ± 0.60 L • min−1 • m−2, p = 0.00000002), the systemic vascular resistance decreased by 42% (from 1604 ± 427 to 930 ± 330 dynes/sec per cm2, p = 0.00001), and the pulmonary capillary wedge pressure (PCWP) decreased by 41.8% (from 23 ± 5.1 to 13.4 ± 6.6 mm Hg, p = 0.00009). Similar results were seen for the patients undergoing destination therapy. Cardiac index increased 89.5% (from 1.9 ± 0.1 to 3.6 ± 0.6, p= 0.046) and PCWP decreased by 52.2% (from 23 ± 10 to 11 ± 2, p = 0.22). In that group, 1 patient died unexpectedly from an accident 382 days after device implantation. The 2 survivors remain in New York Heart Association (NYHA) functional class I at 700 to 952 days after implantation. Conclusions The Jarvik 2000 can offer effective long-term support for patients with chronic heart failure and NYHA class IV status. However, the new physiology produced by continuous offloading of the heart throughout the cardiac cycle has introduced unique clinical problems. The understanding of the problems generated by this biotechnological interface is essential for obtaining optimal clinical outcomes.