Bryan Lynch

Clinical experience with the MicroMed DeBakey ventricular assist device

BACKGROUND The MicroMed DeBakey ventricular assist device (VAD) (MicroMed Technology, Inc, Houston, TX) is the first long-term axial flow circulatory assist device to be introduced into clinical trials as a bridge to transplantation. Clinical trials began in Europe in November 1998 and in the United States in June 2000. METHODS To qualify for the study, the patients must be listed for cardiac transplantation and must have demonstrated profound cardiac failure. There were no exclusions to the MicroMed DeBakey VAD implant other than those patients who would typically be excluded from cardiac transplantation. RESULTS As of September 2000, 51 patients have been implanted with the MicroMed DeBakey VAD. A detailed evaluation of the first 32 patients has been completed. With current data, the probability of survival at 30 days after VAD implant is 81%. CONCLUSIONS The clinical trial demonstrated that the MicroMed DeBakey VAD is capable of providing adequate circulatory support in patients with severe heart failure, sufficient to recover and return to normal activities while awaiting a heart transplantation. Much has been learned about the function of the device and its continuous flow in humans.

Complications common to ventricular assist device support are rare with 90 days of DeBakey VAD® support in calves

The DeBakey VAD® is a miniaturized, electromagnetically driven axial flow pump intended for long-term ventricular assist. Safety and performance data from six calves implanted with the complete DeBakey VAD® system are reported elsewhere; here we describe complications and necropsy findings for these same six animals, all of which survived 90 days. The study was conducted according to a uniform protocol, which included anticoagulation and antibiotic prophylaxis. Clinical complications tracked included bleeding, cardiovascular abnormalities (e.g., arrhythmias, tachycardia unrelated to pain, bradycardia), hemolysis, hepatic dysfunction, renal dysfunction, thromboembolism (neurologic or peripheral), or infection. Each adverse event was retrospectively categorized with regard to severity (mild, moderate, severe) and relationship to device. Clinical findings were confirmed by necropsy. There was no evidence of systemic infection, thromboembolism, hemolysis, or renal or hepatic dysfunction in these six animals during the study period. A single adverse event was noted in each of two of the calves. Both events were considered mild according to the predefined criteria. Bleeding related to the surgical implantation procedure and requiring reoperation occurred in one animal. The other animal had evidence of a superficial infection at the exit site of the cables on the left lateral thoracic wall; the infection did not extend into the thoracic cavity. Chronic, healed small renal infarct scars were present in several animals. Mild valvular endocardiosis was observed in two calves and mild fibroelastosis was present in the endocardium at the site of the inflow cannula in three calves; however, these lesions were not considered clinically significant. No other gross or histologic abnormalities were noted at necropsy. In conclusion, calves implanted with the complete DeBakey VAD® for 90 days demonstrated few complications and had no significant necropsy findings. Complications common to ventricular assist device (VAD) support (i.e., hemolysis, infection, bleeding, thromboembolism) were rare during long-term support (90 days) with the DeBakey VAD.