The Tomasu ventricular assist device (VAD) has been applied to three patients and the Thoratec type of Pierce-Donachy VAD developed in the United State has been applied to two patients in our institutes. Out of the five three patients could be successfully weaned from the VAD, and one of them achieved long-term survival. Non synchronizing pumping of the VADs was significantly effective as well as the synchronizing pumping might be. There were no significant evidences of thromboembolism.
Ventricular Assist Device (VAD) is an effective means of saving patients with severe cardiac failure. I expressed my opinion about status of the VAD and problems of the pump-driven system in Japan. At present, staged or bridged cardiac transplantation utilising apartial artificial heart is available and should be used more often in further to provide effective life for suffering from end-staged cardiac failure.
To improve the performance of vascular prostheses, seeding experiments and measurement of elastic properties of grafts have been carried out. (1) The scanning electron micrograph 6 weeks after implantation showed that the luminal lining of seeded grafts had more cellular ingrowth than control grafts and the efficacy of endotherial cell seeding was demonstrated. (2) Compliance of grafts currently in use was measured using a new type ultrasonic system. In comparison of compliance of human arteries to that of grafts, the difference of compliance between grafts and human arteries was obviously recognized.
The first concept of Single Pump Artificial Heart is that both failed right and left natural ventricles are combined either in series or parallel, to maintain the low pressure pulmonary circulation, while single artificial pump carries the systemic circulation. In the “series” approach, a ventricular septal defect of ca. 3 cm size is created and the mitral valve orifice is closed with a felt patch. A pusher-plate type pump is connected between the LA and the aorta. In the second “parallel” configuration, the atrial septum is removed totally and a pericardial baffle relocates both tricuspid and mitral valves in the new PA. A valved conduit is placed between the LV apex and the main PA so that the LV receives venous blood from the new RA and eject into the pulmonary circulation. A pusher-plate type pump is connected between the new LA and the aorta. The second concept of Single Pump Artificial Heart is that both failed right and left natural ventricles are removed and the atrial septum is also removed totally. Both right and left atrium are anastomosed to create common atrium to maintain low pressure pulmonary circulation, while single artificial pump which is connected between the PA and the aorta carries the systemic circulation. In this method, pulmonary circulation is totally reversed. Preliminary studies indicate that the approach is feasible, and that some number of biventricular failure cases can be treated in this manner using only single artificial heart.