Control of the pulmonary arterial resistance by the use of the oscillated assist flow.

In the clinical application of supporting circulation, the treatment of a patient with pulmonary hypertension is very important. We developed the electromagnetically driven vibrating flow pump (VFP) as a totally implantable type ventricular assist system. The artificial heart driven by electromagnetic forces creates high speed oscillation flow around 10-50 Hz. Assistance by high-speed oscillation flow has an interesting influence on the cardiovascular system. In this study, we carried out research on the influence such oscillation flow had on the pulmonary arterial vessels, and the supporting flow wave-form that controlled pulmonary vascular resistance was considered. Six healthy adult goats of both sexes were used in the experiments. We carried out inhalation anesthesia and performed intubation. The thorax was opened through left fourth rib resection. Right heart bypass was performed from the right atrium to the pulmonary artery. The flow of right heart assistance was maintained within 20-25% of total flow. Our purpose was to add flow of a specific high frequency to the right heart circulation. The hemodynamic parameters were recorded on a magnetic tape data recorder and input into a computer through an A-D converter. A result identified was that the pulmonary vascular resistance changed according to the alteration of the driving frequency of the VFP even during the same flow assistance. The resistance of the pulmonary arterial vessels became smaller when the driving of the VFP of 30 Hz was added to the right heart circulation. This was significant even when compared with continuous flow right heart assist. The characteristics of impedance appeared to have interesting alterations as well. Control of pulmonary vascular resistance by right heart assistance becomes possible if these results are applied. Accordingly, it may become one of the choices for treatment of a patient with pulmonary hypertension.