Abstract
To determine the effects of intravenous nitroglycerin on the velocities and excursions of the acutely ischemic myocardium, 20 open-chest dogs were stud ied by use of ultrasound. In 10 dogs with acute septal ischemia, the posterior wall excursion during contraction (B-C excursion), the mean systolic posterior wall velocity, and the posterior wall excursion remained unaltered. Nitroglyc erin, however, increased all these parameters (P < 0.01). In 10 dogs with acute posterior wall ischemia the B-C excursion (aneurysmal bulging) increased (P < 0.01), but the mean systolic posterior wall velocity and posterior wall excursion decreased (P < 0.01). Nitroglycerin increased even more the aneurysmal bulg ing (P < 0.01) and the other parameters (P < 0.01). Increased regional blood flow, reduced afterload, and mechanical pulling of the ischemic myocardium seem to be a possible mechanism. The measurements were obtained using the recently described method of the specific points.
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