Risk of left ventricular loading during percutaneous cardiopulmonary support in cardiac arrest

BACKGROUNDRecently, circulatory assistance with the Hemopump (Johnson and Johnson Interventional Systems, Warren, NJ) and percutaneous cardiopulmonary support (pCPS) devices has been applied in the clinical setting. Because both of these systems work independently of mechanical and electrical heart function, the spectrum of their clinical application could be broader than that of intra-aortic balloon pulsation. METHODSIn a study of 10 sheep with a mean body weight of 97 kg, the effect of pCPS on the coronary circulation was quantified during cardiac arrest and after ventricular fibrillation was induced. RESULTSPercutaneous cardiopulmonary support stabilized the hemodynamics adequately (pump rate of about 4.5 L/min; aortic pressure of about 50 mm Hg) and provided sufficient coronary circulation (arteriocoronary-venous difference in lactate [acvdiactate] in the range of +0.1 mmol/L when the left ventricular pressure was low, as during cardiac arrest. However, in sheep in ventricular fibrillation we found spontaneous increases in left ventricular pressure that occurred sometimes slowly (n=7; mean left ventricular pressure 36 ± 1.1 mm Hg), sometimes rapidly (n=2), and led to an alignment of left ventricular and aortic pressure. During left ventricular loading the coronary circulation deteriorated and myocardial metabolism switched to anaerobic pathways (acvdlactale in the range of −0.5 mmol/L). Moreover, in some cases (n=4) a parallel rise in pulmonary pressure (in the range of 34 to 46 mm Hg) occurred that resulted in serious damage to the lung. CONCLUSIONSIn summary, left ventricular function should be carefully monitored during pCPS in cardiac arrest. The monitoring of pulmonary capillary wedge pressure is of limited value for estimating the left ventricular pressure loadin most of the animals in this study there was no parallel increase in pulmonary pressure. We conclude that catheter techniques for support of the left ventricular or pulmonary circulation could be considered a valid treatment alternative.