The effects of a centrifugal pump as a left-ventricular-assist device in myocardial infarction

Cardiogenic shock after acute myocardial infarction and open heart surgery having cardiopulmonary bypass may present a difficult clinical problem with high mortality. The present study was carried out to evaluate a newly developed laminar flow centrifugal pump as a left-ventricular-assist device to support the circulation and prevent myocardial damage in such situations. Experimentally induced acute myocardial infarction in dogs was used as the model. Cardiogenic shock was effected by ligating enough branches of the left coronary artery. In addition to recording the haemodynamic parameters, samples of myocardium were taken with a biopsy needle from the infarcted area, transitional zone and intact myocardium for determination of adenosine triphosphate, creatine phosphate and lactate. In the first phase of the work the effects of acute myocardial infarction on haemodynamics and high-energy compounds were defined, to form a basis for the evaluation of the pump as left-ventricular-assist device. Ligation of the branches of the left coronary artery produced a rapid fall in aortic pressure, cardiac output and cardiac performance, elevation of ST-segment in the ECG and fall in high-energy compounds. However, there was a marked spontaneous recovery in the transitional zone within 120 min, despite the haemodynamic deterioration. The laminar flow pump produced a significant improvement in the haemodynamic and metabolic parameters which exceeded the spontaneous changes noted previously.