ABSTRACT
In the evaluation of patients with agina-like chest pain but with insignificant obstructive coronary artery disease, it is important to exclude myocardial ischemia from coronary artery vasospasm. Hyperventilation, like ergonovine and acetylcholine, can also induce myocardial ischemia and its clinical expressions by provoking coronary vasospasm. A possible mechanism for hyperventilation induction of coronary vasospasm is from promotion of an intracellular influx of calcium ions, induced by the alkalotic state, which then stimulates the vascular contractile process, leading to coronary vasospasm. Fifteen patients with anginal-like chest pain [at least one attack per day] were studied. A hyperventilatory ischemic electrocardiographic changes were reported in 11 patients [73.3%] while a hyperventilatory chest pain was reported in 9 patients [60%]. All the positive responses were reported in the posthyperventilation phase or phase II and ventricular ectopics were seen in one patient [6.6%] during the hyperventilation phase, but neither infarction nor arrest have been reported. The hyperventilation test is an alternative diagnostic tool in evaluating patients with angina-like chest pain of unknown etiology and is an effective alternative diagnostic tool for the diagnosis of active coronary vasospasm, especially when spontaneous electrocardiographic evidence of myocardial ischernia, either silent or with chest pain, is not obtained