Effects of extracorporeal circulation on cardiac performance and coronary blood flow (total and regional). A study of differences arising from pre-existent left ventricular load and anoxic arrest.

Abstract

It was researched how the ECC affects on cardiac performance and the total and regional coronary blood flow, using two groups of dogs with a hypertrophied heart and a non-hypertrophied heart, each group of which was further divided into two subgroups depending on whether the intermittent 40 mins. anoxic arrest was applied or not. Cardiac performance before and 60 mins. after cessation of ECC were compared each other. Coronary hemodynamics was studied before, during (immediately before and after anoxic arrest), and 60 mins. after cessation of ECC, using 15 +/- 5 diameter radioactive microspheres. 1) In the group of a non-hypertrophied heart, no obvious changes of cardiac performance were seen before and after ECC. The total coronary blood flow increased after ECC than before. Though the regional coronary blood flow pattern showed no differences in this group except only immediately after anoxic arrest, when the regional blood flow into the right ventricle, inner and middle layers of the left ventricle increased. 2) In the group of a hypertrophied heart, cardiac performance decreased after ECC, and further significant decrease was observed in the subgroup of anoxic arrest. No significant changes of the total coronary blood flow were observed before and after ECC in this group, even when compared with that in the group of a non-hypertrophied group. However, the increase of blood flow to the right ventricle, inner and middle layers of the left ventricle immediately after anoxic arrest was not observed, that was seen in the group of a nonhypertrophied heart. 3) It follows that the decrease of cardiac performance after ECC in the group of a hypertrophied heart is not due to the changes of the total and regional coronary blood flow. It is considered that the difference of the regional coronary blood flow pattern changes immediately after anoxic arrest between the non-hypertrophied heart group and hypertrophied group may cause the different changes of cardiac performance before and after ECC between the two groups. This consideration should be more justified by evaluating not only coronary hemodynamics but also the relationship between cardiac metabolic needs and the regional coronary blood flow.