Remove before MRI, cardioversion or DC defibrillation, or diathermy treatment. Patients w/ recent MI & acute heart failure. Patients w/ arterial hypoxaemia due to severe anaemia, hypoxaemia & ventilation/perfusion imbalance due to lung disease or ischaemic heart failure. Patients w/ angina pectoris, MI or cerebral ischaemia. Hypertrophic cardiomyopathy. Increased frequency of angina during patch-off periods. Tolerance to SL nitroglycerin. Infusion site should be examined regularly for development of phlebitis. May impair ability to drive or operate machinery. Pregnancy & lactation.