Haemodynamic comparison of different routes of nitrate administration in postmyocardial infarction left ventricular failure.
An open randomised parallel group comparison of the haemodynamic effectiveness of three different routes of nitrate administration was undertaken in 36 male patients aged 40-69 years who had developed acute left ventricular failure within 18 h of the onset of myocardial infarction. All patients had electrocardiographic and serum cardiac enzyme changes compatible with transmural myocardial infarction and all had both radiographic and haemodynamic evidence of left ventricular failure. None were hypotensive, all were in sinus rhythm and none were receiving other cardioactive drugs. Control haemodynamic measurements were made over a period of one h, following which patients were randomised to receive either intravenous isosorbide dinitrate (mean dose 12.9 mg; range 7.7-14.9), buccal nitroglycerine (5 mg) or transdermal nitroglycerin (nitro TTS 10). The raised left heart filling pressure was reduced by all nitrate preparations but none significantly changed the heart rate or cardiac output. Systemic arterial pressure and vascular resistance were reduced by i.v. ISDN and buccal NTG but not by a transdermal NTG. The only adverse circulatory reaction was hypotension in the three patients following buccal NTG. Nitroglycerin by the transdermal route appears to be equally effective in reducing the raised left heart filling pressure in patients with postinfarction heart failure without the practical disadvantages of monitoring its intravenous administration or the potential hazard of hypotension with buccal NTG.