Effect of high-volume cardioplegia on small-amplitude electrical activity during cardioplegia arrest

The effects of high-volume cardioplegia on the presence of small-amplitude electrical activity during cardioplegia arrest were investigated in 19 mongrel dogs. The animals were randomly assigned to receive either high-volume crystalloid cardioplegia (HV-plege) or crystalloid cardioplegia guided by continuous electrical monitoring (V-plege). Cardiac index, left ventricular stroke work index dp/dt, and myocardial oxygen consumption were measured before bypass and following 90 min ischemia and 45 min reperfusion. Biopsies were taken for measurement of adenosine triphosphate (ATP) and examination of myocardial ultrastructure. Nine animals received HV-plege, while the remaining 10 animals received cardioplegia guided by voltage criteria. Small-amplitude electrical potentials were recorded within 10-15 min after the infusion of cardioplegia in all animals receiving cardioplegia guided by voltage criteria. Electrical activity, however, was immediately abolished by reinfusion of cardioplegia. HV-plege reduced the incidence of small-amplitude electrical activity during cardioplegia arrest but did not prevent electrical activity. Left ventricular function and myocardial ultrastructure were better preserved when cardioplegia was guided by electrical monitoring. ATP decreased similarly in both groups following cardioplegic arrest, but myocardial oxygen consumption was significantly higher following the arrest in the V-plege group.

HV-plege does not prevent small-amplitude electrical activity and may have adverse effects on myocardial metabolic and functional recovery.