Haemodynamic aspects of nitrate tolerance.

Development of tolerance to the haemodynamic effects of nitrates is influenced by the degree of left ventricular dysfunction and a number of other factors related to the circulatory system. Patients with angina pectoris and normal cardiac function at rest differ in response compared with patients with chronic congestive heart failure. Several studies have shown that haemodynamic tolerance to nitrates will develop in patients with angina pectoris. Slow-release oral nitrates and transdermal nitrates, as well as higher dosages, are more likely to induce tolerance. Patients with congestive heart failure will usually not develop tolerance after oral nitrate therapy. With transdermal therapy, however, tolerance frequently develops even in these patients. The individual response of patients to the effects of nitrates and the development of tolerance is variable, regardless of clinical status. Future studies on the development of tolerance must consider the complexity of the effects of nitrates and the various factors that may affect the haemodynamic changes.