Sustained hemodynamic effects with therapeutic doses of intravenous nitroglycerin in congestive heart failure

Influence of hemodynamic changes on neuroendocrine response in acute heart failure

We studied 15 patients with acute deterioration of chronic left ventricular heart failure. We compared the influence of reduction of ventricular filling pressures with glyceryl trinitrate versus reduction of ventricular filling pressures with diuretics on plasma concentration of epinephrine, norepinephrine, aldosterone and renin activity. Reduction of ventricular filling pressures with glyceryl trinitrate had no influence on plasma concentrations of epinephrine, norepinephrine, aldosterone and renin activity. After reduction of ventricular filling pressures with diuretics plasma concentrations of epinephrine, norepinephrine and aldosterone decreased, while plasma renin activity did not change. We conclude that there is a difference in the influence of reduction of ventricular filling pressures with glyceryl trinitrate versus reduction of ventricular filling pressures with diuretics, on neuroendocrine response in patients with acute deterioration of left ventricular heart failure. Thus some of the neuroendocrine effects of glyceryl trinitrate are likely to be different from those of diuretics, though that they both produce a reduction in left ventricular filling pressure.

Nitrates: why and how should they be used today? Current status of the clinical usefulness of nitroglycerin, isosorbide dinitrate and isosorbide-5-mononitrate

Nitrates are highly effective both in terminating acute attacks of angina pectoris and in the prophylaxis of symptomatic and asymptomatic myocardial ischemia. Preload reduction by venodilatation is the prevailing mechanism of nitrates in patients with chronic stable angina and is the unique feature distinguishing them from beta and calcium-channel blockers. Nitrates dilate coronary arteries not only in pre- and poststenotic vessels, but also in eccentric lesions. In patients with endothelial dysfunction, nitrates seem to be the physiological substitute for endothelium-derived relaxing factor. During the past decade, however, there has been substantial evidence of a clinically relevant loss of the anti-ischemic effects ("nitrate tolerance"). Many studies with oral dosing of isosorbide dinitrate or isosorbide-5-mononitrate at least three times daily have proven nitrate tolerance in patients with coronary artery disease and/or congestive heart failure. Complete loss of anti-ischemic effects after repetitive, continuous patch attachments has also been found. As we first showed in 1983, intermittent therapy with once-daily ingestion of high-dose sustained-release isosorbide dinitrate was successful in preventing the development of tolerance. Similarly, tolerance to isosorbide-5-mononitrate also does not develop when it is ingested once daily. It is now generally accepted that a daily low-nitrate interval is required to prevent tolerance development. Although the minimal patch-free interval required to prevent tolerance needs further investigation, a 12-h patch-free interval should prevent tolerance in most patients. The prolonged duration of action of once-daily high-dosage administration of sustained-release formulations, the improved patient compliance with a single daily administration, and the increased likelihood of maximal anti-ischemic effects are important reasons for recommending high single daily doses of isosorbide dinitrate or isosorbide-5-mononitrate.