Summary
Intramyocardial temperature gradients developing during and following cold infusion
cardioplegia were studied in patients operated upon for coronary and for valvular
heart disease as a function of systemic blood- and ambient temperatures. Following
cardioplegic infusion septal temperature fell more profoundly than that of the lateral
and particularly the inferior wall of the left ventricle in both groups of patients.
In those with multiple coronary heart disease and in the presence of grossly viable
myocardium, distribution of cold within the left ventricle was not affected by the
degree of coronary obstruction. The spontaneous septal rewarming rate was greater
in coronary than in valvular heart diesease. The rate of temperature rise at any of
the measuring sites depended upon the level of systemic blood temperature, on the
removal of warm collateral blood from the cardiac cavities and particularly upon the
presence or absence of cold pericardial irrigation. It is concluded that near homogeneous
cooling of the heart only can be achieved and maintained in clinical cardioplegia
when the influence of extracavitary and intracavitary heat sources is minimized. In
prolonged clinical cardioplegia systemic blood temperature should be kept low, the
cardiac cavities drained of collateral blood, topical cooling maintained and the heart
shielded within the pericardium.
Key words
Cardioplegia - Topical cooling - Temperature gradients - Myocardial
