The Poststenotic Vessel Segment during Dynamic Exercise: Effect of Oral Isosorbide-dinitrate

Abstract

Coronary vasomotion of normal, stenotic, and poststenotic vessel segments was studied in 18 patients with coronary artery disease at rest, during submaximal bicycle exercise, and 5 min after sublingual nitroglycerin or oral isosorbide-dinitrate (ISDN) spray. Patients were divided into two groups: group 1 consisted of 10 patients with no premedication prior to exercise, and group 2 consisted of 8 patients receiving 120 mg long-acting ISDN orally 1 h before the procedure. Quantitative coronary arteriography was carried out in biplane projection using a semi-automatic computer system. The normal vessel segment showed a trend toward a small increase in cross-sectional area during exercise in both groups (+3% in group 1 and +4% in group 2, both NS). After sublingual nitroglycerin following exercise, there was a significant increase in group 1 (+29%, p less than 0.001 vs rest) but not after ISDN spray in group 2 (+5%, NS vs rest). The stenotic vessel segment showed exercise-induced stenosis narrowing in group 1 (-31%, p less than 0.01 vs rest) which was prevented by oral ISDN (+6%, NS vs rest). After exercise, sublingual administration of nitroglycerin or ISDN spray was associated with no significant change in stenosis area in either group. The poststenotic vessel segment showed no significant vasomotion during exercise in both groups (area change +6% in group 1 and +7% in group 2), but poststenotic luminal area increased after sublingual nitroglycerin (group 1: +15%, p less than 0.01 vs rest) or ISDN spray (group 2: +15%, p less than 0.05 vs rest). The mean pulmonary artery pressure increased during exercise from 22 to 39 mmHg (p less than 0.001) in group 1 and from 14 to 27 mmHg (p less than 0.001) in group 2. At rest (p less than 0.001) and during exercise (p less than 0.01) mean pulmonary pressure was lower in group 2 than in group 1. Thus, it is concluded that coronary vasomotion of the poststenotic vessel segment is only minimal during exercise and is not affected by coronary vasomotion of the stenotic vessel segment. Pretreatment with oral ISDN did not influence coronary vasomotion of the poststenotic vessel segment, but prevented exercise-induced stenosis narrowing. In the untreated patients, vasoconstriction of the stenotic vessel segment is limited to the site of the stenosis, and it appears that there is no release of vasoactive substances with vasoconstrictive influences on the poststenotic segment.