Resuscitation and Emergency Medicine
Myocardial function following cardiopulmonary resuscitation in a pig model of myocardial infarction
Background and Goal of Study: Results in research on cardiopulmonary resuscitation (CPR) in different animal models and outcome in humans undergoing CPR, still differ. One reason for this discrepancy could be that experimental studies use young and healthy animals while in most cases humans undergoing CPR suffer from acute or chronic myocardial dysfunction . To overcome this problem, we developed a pig model of myocardial infarction which compromises myocardial function significantly without rendering CPR impossible.
Materials and Methods: A median thoracostomy was performed in 12 pigs and they were instrumented for measurement of mean arterial pressure (MAP), left ventricular pressure (LVP) and cardiac index (CI). LVP was processed for maximal contractility (dP/dt). Animals in group 1 (G1, n = 6) received no further preparation. In group 2 (G2, n = 6) myocardial infarction was induced by clipping the circumflex artery (RCX) close to its origin, which was performed immediately after induction of a four minute cardiac arrest by ventricular fibrillation. CPR was carried out according to the AHA guidelines. Statistical analysis: Mann-Whitney-U-test, p < 0.05 considered significant, data expressed as mean ± SD.
Results and Discussions: At baseline there were no significant differences between G1 and G2. All animals were resuscitated successfully. Myocardial infarction affected 39 ± 5% (G2) of the mass of the left ventricle and resulted in a significantly reduced cardiac index and myocardial contractility after return of spontaneous circulation (ROSC).
Conclusion: Clipping of the RCX provides reproducible myocardial infarction in pigs and leads to a significant decreased myocardial function after CPR. Therefore, this setup provides a clinically highly relevant model for future CPR studies.
© 2004 European Society of Anaesthesiology
1 Wennerblom, B. and S. Holmberg. Eur Heart J, 1984. 5
(4): p. 266-74.