Effect of extracorporeal membrane oxygenation on left ventricular functionof swine

Background. Previous clinical and experimental investigations have produced inconsistent data describing the effects of veno-arterial extracorporeal m embrane oxygenation (VA ECMO) on intrinsic left ventricular (LV) function. We report an animal model that allows investigation of the effects of VA EC MO on the mechanics of the LV using two load-insensitive indices: end-systo lic pressure-minor axis dimension relationship (ESPDR) and preload recruita ble dimensional stroke work (PRDSW). Methods. Eight piglets (5 to 11 kg) were anesthetized, instrumented, and pl aced on VA ECMO. Throughout the experiment, systemic and left atrial partia l pressure of oxygen were maintained between 100 to 200 mm Hg. At ECMO flow rate of 50% of baseline cardiac output, data were collected prior to ECMO, at 4 and 6 hours during ECMO, and after weaning from ECMO. Data measured o r calculated for each time point included heart rate, LV pressures and mino r axis dimensions at different preloads, first derivative of LV pressure wi th respect to time, velocity of circumferential fiber length shortening (VC F), LV shortening fraction (LVSF), ESPDR, and PRDSW. Results. A significant (p < 0.05) decrease in LVSF and VCF was seen at 4 an d 6 hours during ECMO when compared to baseline, but the ESPDR and PRDSW di d not change during ECMO. Conclusions. VA ECMO alone changes some of the load-dependent parameters of contractility, but intrinsic function of the heart is not significantly af fected as measured by load-insensitive indices of LV performance. (C) 2001 by The Society of Thoracic Surgeons.