Optimal pulse pressure of pulmonary circulation under bi-ventricular assist after cardiogenic shock

In order to evaluate an appropriate pulse pressure of pulmonary circulation during bi-ventricular assist, an experimental study was carried out in swine. The cardiogenic shock model was made by the left anterior descending (LAD) ligation method. When the hear fibrillated due to acute myocardial infarction, both left and right hearts were supported by ventricular assist devices (VADs) for two hours. The left heart assist was operated with a pneumatic pulsatile ventricular assist device (VAD) and the right was operated with a pneumatic VAD or centrifugal pump. According to the pulse pressure of the pulmonary artery these models were divided into three groups: Low-P group (n = 3), in which a low pulse pressure (less than 20 mmHg) was made by VAD, High-P group (n = 5), in which over 20 mmHg of pulse pressure was initiated. NP group (n = 10), in which nonpulsatile assist was done with a centrifugal pump. In pulmonary gas exchange, the Low-P group was superior to the other two groups. The average PaO2 was 214+/-57 mmHg in the Low-p group, and 117+/-41 mmHg and 148+/-81 mmHg in the NP group and High-P group respectively. In the pathological study, a remarkable extension of pulmonary lymphoducts was found in the High-P group. On the other hand, this change was not recognized in other groups. These results suggested that pulmonary microcirculation might deteriorate due to high pulse pressure of the pulmonary artery. We consider the most suitable pulmonary pulse pressure to be around 20 mmHg to maintain normal pulmonary circulation.