Evaluation of nitrate tolerance in patients with coronary heart disease byvascular ultrasonography and treadmill exercise

The aim of this study was to evaluate nitrate tolerance in patients with co ronary heart diseases by vascular ultrasonography and treadmill exercise. A ccording to the dosage interval of isosorbide dinitrate, 66 patients with c oronary heart disease were divided into group A and group B in a random, co ntrol and double-blind method. Isosorbide dinitrate was given every 6 hours in group A and every 12 hours in group B for one week. Before and after th e therapeutic period, the diameters of brachial arteries were measured by v ascular ultrasonography at baseline and 5 min after sublingual administrati on of 10 mg isosorbide dinitrate, and the treadmill exercise test was perfo rmed in all subjects. The results showed that diameters of brachial arterie s were increased significantly after sublingual isosorbide dinitrate in bot h groups before the therapeutic period. After the therapeutic period, dilat ion of brachial arteries induced by sublingual isosorbide dinitrate was mor e marked in soup B than in group A. Compared with those before the therapeu tic period, CST segment depression decreased and treadmill walking time inc reased significantly in group B but not in group A after the therapeutic pe riod. These findings suggest that less frequent doses of isosorbide dinitra te may prevent development of nitrate tolerance, which is confirmed by vasc ular ultrasonography combined with treadmill exercise in patients with coro nary heart disease. (C) 1999 Elsevier Science Ireland Ltd. All rights reser ved.