Myocardial protection by warm blood cardioplegia. A 31P nuclear magnetic resonance spectroscopy study of an isolated perfused rat heart.
OBJECTIVE
A study of the protective efficiency imparted by intermittent warm blood cardioplegia (WBCP) using perfused rat heart model.


METHODS
Hemodynamic parameters were monitored simultaneously with metabolic changes in high-energy phosphates using 31P-NMR spectroscopy. Following 30 min perfusion with Krebs-Henseleit (KH) buffer, all hearts were arrested for one hour (G1 and G2) and than reperfused with KH for 30 minutes. A warm oxygenated crystalloid cardioplegia (WCCP, modified St Thomas' hospital solution) was used for the control group (G1). The second group of hearts (G2) were arrested with oxygenated WBCP (K+ = 15 mM; Hct = 15-20%) and the third group (G3), was subjected to a protocol consisting of 4 periods (10 min each) of WBCP interspersed by 10 min of global ischaemia.


RESULTS
The post-arrest percentage recoveries of LVDP, +dP/dt and HR were respectively: 88, 93 and 90 for G1 (n = 8); 97, 100 and 98 for G2 (n = 10); 76, 79 and 91 for G3 (n = 12). The corresponding metabolic recoveries of ATP and PCr were respectively, 85 and 90 for G1; 91 and 98 for G2 and 73 and 85 for G3. The PCr level declined during the arrest period in G1 contrasting with elevated PCr level (> 140%) during the WBCP arrest in G2. After an initial rise to approximately 140%, PCr level gradually decreased during the intermittent WBCP interval (G3).


CONCLUSIONS
At normothermia, with equal CF rates, continuous WBCP provides better myocardial protection, through an effective oxygen supply, compared with WCCP. During the intermittent periods of ischaemia, certain metabolic and hemodynamic dysfunction occurs.
D000818:Animals; D010478:Chemotherapy, Cancer, Regional Perfusion; D004195:Disease Models, Animal; D006321:Heart / Q000502:physiology* / Q000503:physiopathology; D006324:Heart Arrest, Induced; D006439:Hemodynamics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D017202:Myocardial Ischemia / Q000517:prevention & control*; D010761:Phosphorus Radioisotopes; D051381:Rats; D017207:Rats, Sprague-Dawley
D010761:Phosphorus Radioisotopes