Anginal Syndrome Induced by Gradual General Anoxemia

Abstract

With individuals subject to attacks of chest pain, in whom there is no evidence by physical or electrocardiographic examination of myocardial (coronary) disease, it is often difficult to be certain of the origin of the pain. We wished to distinguish between those with pain due to impaired coronary circulation, and those in whom the pain arose otherwise. It occurred to us that if one were to produce a general anoxemia, and, therefore a local cardiac anoxemia, there might appear differentiating responses in these 2 groups.

By means of rebreathing, we were able to produce a state of general anoxemia in human subjects. The carbon dioxide was absorbed. It usually took about 10 minutes for the oxygen to become so low that the patient became uncomfortable.

Twenty-seven patients were subjected to the test. Fourteen patients were used as controls. The controls consisted of 4 patients with normal hearts. The remaining cases were patients with chronic valvular disease, paroxysmal auricular fibrillation, rheumatic fever, spondylitis, gall bladder disease, and cardiospasm. None of these patients developed pain. Thirteen were patients with clear-cut histories of attacks of precordial pain brought on by exertion, excitement, eating, or exposure to cold. Ten developed pain during the rebreathing test. Eight of these had no physical or electrocardiographic signs of myocardial disease. The pain appeared when the oxygen fell to about 9 to 10%. This ordinarily took about 8 to 10 minutes. Subjects were advised to raise their hands when they felt uncomfortable, and the experiment was stopped.

It is furthermore interesting to observe that 2 other patients with clinical angina and intra-ventricular block developed pain and additional electrocardiographic changes during the anoxemia.