Effects of hypoxia, cyanide, and ischaemia on myocardial contraction: observations in isolated muscle and intact heart.

Using potassium cyanide (KCN) to stimulate hypoxia, the effects of intracoronary injections of KCN were compared with total occlusions of the same vessel. Imparied contraction as measured by segment length gauges was of equally abrupt onset following both interventions. The magnitude of systolic expansion at one minute was more marked following total occlusion than after KCN administration.