European Journal of Cardio-Thoracic Surgery, Vol 3, 203-207, Copyright © 1989 by European Association for Cardio-thoracic Surgery
Monitoring the voltage of the myocardium during cardioplegia arrest
RW Landymore and AE Marble
Department of Surgery, Dalhousie University, Halifax, Nova Scotia, Canada.
Electrical activity was monitored with specially designed plunge electrodes
in 19 animals undergoing 3 h of cardioplegic arrest. Electrical activity
was recorded on electromagnetic tape and intramyocardial voltage was
monitored with an inline voltmeter. Haemodynamic function was assessed
before bypass and following 3 h of ischaemia and 45 min of reperfusion.
Intramyocardial voltage during normothermic fibrillation measured 2.4 +/-
0.4 mv. Infusion of cardioplegia initiated a complete electrical arrest in
all animals and reduced intramyocardial voltage to 33 +/- 7 mu v. Small
amplitude electrical activity was present in 9 of 19 animals.
Intramyocardial voltage increased to 108 +/- 12 mu v with the onset of
small amplitude electrical activity and spectral analysis of the wave form
indicated that the fundamental frequency was in the range of 3.08 Hz. Small
amplitude electrical activity during cardioplegic arrest was associated
with significant post-arrest depression of left ventricular function. Our
data confirms that the presence of small amplitude electrical activity
impairs myocardial functional recovery and suggests that continuous
intramyocardial voltage monitoring may be used to guide the administration
of cardioplegia during cardioplegic arrest.
