In support of nitrate ointment for patients with acute myocardial infarction.

Glyceryl trinitrate (GTN) is a potent vasodilator. It causes venodilatation which reduces venous return to the heart and thus reduces preload and also causes arterial vasodilatation which reduces left ventricular afterload. In angina pectoris these effects reduce myocardial wall tension and thereby reduce myocardial oxygen consumption and arterial vasodilatation increases myocardial oxygen delivery. In heart failure left ventricular filling pressures are high causing pulmonary venous congestion and pulmonary oedema and preload reduction improves these. Afterload reduction also improves forward flow and cardiac output. Thus, nitrates have important haemodynamic effects in the context of ischaemic heart disease.