Coronary sinus potassium concentration recorded during coronary angioplasty.

Coronary sinus potassium concentration was measured continuously in two patients undergoing angioplasty of a significant stenosis of the left anterior descending coronary artery. After each coronary occlusion there was a transient rise in coronary sinus plasma potassium concentration caused by washout of potassium which had accumulated in the extracellular fluid during the short period of ischaemia. There were no significant changes in the surface electrocardiogram and the patients experienced no chest pain. Changes in coronary sinus potassium concentration provide a sensitive and early indication of myocardial ischaemia in man.