Influence of Cooling the Heart on Reactive Hyperemia of the Coronary Bed in the Heart-Lung Preparation
Left coronary artery inflow was recorded in the dog heart-lung preparation by means of a Gregg cannula and a Shipley-Wilson recording rotameter. Reactive hyperemia (RH) was induced by 10-second occlusions. The excess blood flow after release was quantified by planimetry and related to the "blood flow debt" incurred during the period of occlusion. In the normothermic heart, the excess coronary flow was 431% of the flow debt. At heart temperatures of 30 and 25.6° C, it dropped to 228% and 143% respectively. There was shortening of the duration of reactive hyperemia and reduction of peak flow at lower temperatures. These results were discussed in the light of chemical theories of the mechanism of reactive hyperemia and the effect of hypothermia thereon.
- Received June 26, 1964.
- © 1965 American Heart Association, Inc.