The effect of infusion of sodium nitroprusside on S-T segment elevation was evaluated in 12 patlents with acute anterior myocardial infarction. Precordial 35 lead S-T segment maps were obtained in each patient immediately before and 10 minutes after infusion of 53 μ/min (range 20 to 100 μg/min) of nitroprusside. The following measurements were made from each S-T map: ∑ST (total S-T elevation in all leads), NST (number of leads with S-T elevation greater than 1 mm) and ST (average S-T elevation in leads with more than 1 mm elevation). After administration of nitroprusside, evidence of myocardial ischemic injury as assessed by S-T mapping decreased in association with reduction of the myocardial oxygen consumption index of pressure-time per minute. Group mean values diminished significantly for ∑ST (41.7 to 28.6 mm, P <0.001), NST (20.3 to 14.6, P <0.001) and ST (1.6 to 1.2 mm, P <0.005). Pressure-time per minute decreased from 2,690 to 2,372 mm Hg-sec/min (P <0.001). Because there was no significant relation (P >0.05) between reductions in S-T elevation and lower indexes of myocardial oxygen consumption, it is suggested that nitroprusside may possess a separate action of augmenting regional blood flow to ischemic myocardium. Evaluation with the precordial S-T mapping technique suggested that intravenous administration of nitroprusside was associated with evidence of reduced ventricular ischemic injury in patients with acute myocardial infarction. This effect appears to be related to reduction of myocardial oxygen demand by the peripheral cardiac unloading mechanisms of nitroprusside as well as to a possible direct action of the drug in improving regional blood flow to ischemic heart muscle.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine