Conditions: Healthy
Keywords: To determine if topical nitroglycerin acts to vasodilate the radial artery by a direct local action, or by systemic vasodilation To determine if topical nitroglycerin dilates the radial artery in the presence of local anesthetic agents used in cardiac catheterization
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 19
Healthy volunteers: yes

Brief summary:
The radial artery, which is located on the outer side of the forearm, can be used in interventional procedures, such as cardiac catheterization, to provide access to the arterial blood supply. In order to facilitate successful catheterization of the artery, a dilated artery and one free of arterial spasm is desirable. The proposed study will randomize twenty three healthy subjects in 2 visits to determine the effect of topical nitroglycerin on radial artery vasodilation. Radial artery diameter will be measured with ultrasound at regular intervals up to two hours.

Detailed description:
During the first study visit, as a dose-optimizing study, each subject will be randomly assigned to one of two Dose-Test arms to receive either 15mg or 30mg of nitroglycerin on one wrist and placebo on the other. Radial artery diameter will be measured with ultrasound at regular intervals up to two hours. On the second study visit, the same participants will be randomly assigned to one of two Combination-Test arms to receive bilateral topical application of either 20mg or 40mg of lidocaine; the lidocaine will be applied in combination with 30mg of nitroglycerin on one wrist and in combination with placebo on the other wrist. Measurements of radial artery diameter will be performed as in the first visit.

Arms:
arm 1: Nitroglycerin 15mg (NTG) applied topically to one wrist and placebo to the other wrist at Visit 1 arm 2: Nitroglycerin 30mg applied topically to one wrist and placebo to the other wrist at Visit 1 arm 3: Lidocaine 20mg + Nitroglycerin 30mg applied topically to one wrist, Lidocaine 20mg + placebo applied to the other wrist, at Visit 2 arm 4: Lidocaine 40mg + Nitroglycerin 30mg applied topically to one wrist, Lidocaine 40mg + placebo applied to the other wrist, at Visit 2

Interventions: intervention 1: Nitroglycerin 15mg intervention 2: Nitroglycerin 30mg intervention 3: Lidocaine 20mg intervention 4: Lidocaine 40mg intervention 5: Placebo
Intervention descriptions: intervention 1: 15mg Nitroglycerin applied topically to one wrist intervention 2: 30mg Nitroglycerin applied topically to one wrist intervention 3: 20mg Lidocaine applied topically to one wrist in combination with nitroglycerin or placebo intervention 4: 40mg Lidocaine applied topically to one wrist in combination with nitroglycerin or placebo intervention 5: Topical skin moisturizing cream with same appearance as active agent

Protocol document: