Ventricular dysrhythmias following intravenous dipyridamole during “stress” myocardial imaging

Abstract

Dipyridamole has vasodilator properties, particularly in the coronary circulation, and for this reason is used during thallium myocardial imaging to accentuate regional perfusion abnormalities (Albro et al, 1978, Wilde et al, 1982). Such coronary vasodilatation, using dipyridamole intravenously, reveals areas of myocardial ischaemia as effectively as maximal treadmill exercise (Albro et al, 1978). Recently, combined exercise and dipyridamole thallium scanning has been reported to be more accurate, giving an increase in image quality and diagnostic yield, and was safer than exercise alone (Wilde et al, 1982). Unwanted effects of dipyridamole, as a result of vasodilatation, include headache and hypotension. Angina can occur, presumably due to “steal” effect after coronary vasodilatation, but is usually reversed by nitrates (Brown et al, 1981) or aminophylline, a pharmacological antagonist of dipyridamole (Afonso, 1970). Life-threatening side-effects have not been reported.