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Organic nitrates are potent vasodilators that are often used therapeutically to treat cardiovascular disease. 1 The biochemical basis of their pharmacological action is the release of nitric oxide from the nitrate group, which activates enzyme soluble guanylate cyclase, leading to the accumulation of cyclic guanosine monophosphate and subsequent vascular relaxation.2 3 Through this mechanism, organic nitrates exert a wide spectrum of physiological actions by dilating peripheral and regional arterial and venous smooth muscle coronary blood vessels, thus increasing coronary blood flow. These effects lead to a decrease in myocardial oxygen demand and preload as well as an increase in oxygen supply, producing symptomatic relief in angina pectoris and congestive heart failure. 4 5 Aside from the biochemical and physiological effects that are common to all nitrates, individual nitrates differ substantially in their pharmacological potency and pharmacokinetics. 6 Experimental work has shown different sensitivity to nitrates in various vessel sections. 7 8
Sublingual nitroglycerin (glyceryltrinitrate, GTN) capsules or isosorbide dinitrate (ISDN) spray are routinely used to treat anginal attacks and to maximally vasodilate the epicardial coronary arteries during coronary angiography. Alternatively, GTN can be given by the intracoronary route. The safety and efficacy of these modes of treatment are well established, 7 9 but a controlled comparative study of the effect of these different methods of application on coronary artery calibre has not been reported.
This study aimed to investigate the coronary vasodilatory effects of different nitrate preparations using quantitative coronary angiography. Sublingual GTN capsules and ISDN spray were compared with intracoronary GTN.
Methods
Ninety six patients (79 men and 17 women; median (range) age 59 (35-77) years) were studied (table 1 ).
Group 1 (ic/spray) (n = 26) | Group 2 (ic/caps) (n = 21) | Group 3 (caps/ic) (n = 27) | Group 4 (spray/ic) (n = 22) | |
Mean (SD) age (years) | 57 (2.1) | 56 (2.3) | 57 (2.1) | 59 (2.3) |
Sex (F/M) | 7/19 | 3/18 | 2/25 | 5/17 |
Coronary artery disease | 22 (85%) | 17 (81%) | 22 (81%) | 21 (95%) |
p values not significant for all parameters.
ic, intracoronary nitroglycerin; spray, isosorbide dinitrate spray; caps, sublingual glyceryltrinitrate capsule.
PATIENT SELECTION
Patients undergoing diagnostic coronary angiography without contraindication to nitrates were eligible. Patients were excluded if they: had received treatment with nitrates or calcium antagonists, or both, less than 24...