Intermittent warm blood cardioplegia does not provide adequate myocardial resuscitation after global ischaemia.
OBJECTIVE
Intermittent warm blood cardioplegia is controversial, and many surgeons consider it inadequate for myocardial protection. The purpose of this study was to compare intermittent and continuous warm blood cardioplegia as resuscitation in hearts exposed to global ischaemia.


METHODS
Pigs were put on cardiopulmonary bypass (CPB) and subjected to 30 min of warm, "unprotected", global ischaemia, followed by continuous (n = 7) or intermittent (n = 10, 12 ml/kg every 10 min) warm (34 degrees C) antegrade blood cardioplegia for 45 min (delivery pressure 75-80 mmHg) and weaned from CPB 45 to 60 min later. Indices of left ventricular function were acquired with the conductance catheter technique and pressure-volume loops at baseline and after 90 min of reperfusion.


RESULTS
Cardioplegia was delivered during 17% of the cross-clamp time. Global left ventricular function, evaluated by preload recruitable stroke work (PRSW), was unchanged after continuous cardioplegia; 95 (76-130) (median (quartile interval)) to 91 (90-104) erg/ml x 10(3), but decreased after intermittent cardioplegia; 122 (100-128) to 64 (23-93) erg/ml x 10(3). Two pigs in the intermittent group weaned from CPB, but died before post-bypass measurement. A 95% confidence interval for the difference in post-bypass mean PRSW was estimated as 32 +/- 30 erg/ml x 10(3) (corresponding to P = 0.04 for comparison between treatments). The end-diastolic pressure-volume relation (EDPVR) increased from 0.17 (0.14-0.20) (continuous) and 0.15 (0.12-0.22) (intermittent) mmHg/ml to 0.27 (0.22-0.33) (P = 0.018) and 0.39 (0.25-0.66) (P = 0.005) mmHg/ml, respectively, indicating deterioration in diastolic function. No difference between groups was found in EDPVR, stiffness constant, troponin T release or myocardial water content.


CONCLUSIONS
Following acute global ischaemia left ventricular global function was, in this model, less preserved using warm intermittent compared to warm continuous cardioplegia.
Ericsson
A B
AB
Department of Thoracic Surgery, Karolinska Hospital, Stockholm, Sweden.
Kawakami
T
T
Vaage
J
J
D000818:Animals; D001794:Blood Pressure; D001834:Body Water / Q000378:metabolism; D002315:Cardiopulmonary Bypass; D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004195:Disease Models, Animal; D006323:Heart Arrest / Q000150:complications / Q000628:therapy; D006324:Heart Arrest, Induced / Q000379:methods*; D006979:Hyperthermia, Induced; D007511:Ischemia / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D013318:Stroke Volume; D013552:Swine; D016896:Treatment Outcome; D020107:Troponin T / Q000097:blood
D020107:Troponin T