Evaluation of acute stress-induced regional myocardial ischemia: comparison of regional contractile and metabolic indices to easily accessible global left ventricular indices.

Abstract

In clinical studies stress-induced myocardial ischemia in patients with coronary artery disease is used to evaluate the severity of this disease. The discussion on the importance of some parameters measured during this intervention is controversial, other parameters are difficult to obtain. On the basis of an experimental model of stress-induced myocardial ischemia, we tried to find an index that reflects best this cardiac state. We therefore compared in eight anesthetized open-chest dogs control conditions with three other hemodynamic states with increasing imbalance between myocardial oxygen demand and oxygen supply: severe stenosis on circumflex coronary artery, 60 s cardiac sympathetic nerve stimulation (CSNS) with a severe stenosis on circumflex coronary artery, and 60 s complete occlusion of circumflex coronary artery. Using a one-way analysis of variance, we found two significantly changed parameters during the stress-induced ischemia: Regional lactate extraction was turned to production (32 +/- 4 vs. -4 +/- 1%) and the ratio of dP/dtmin to dP/dtmax was decreased (1.13 +/- 0.05 vs. 0.67 +/- 0.05; control vs. CSNS with a severe stenosis on circumflex coronary artery). We conclude that the ratio of dP/dtmin to dP/dtmax is an easily accessible, sensitive, and dynamic index for characterization of an stress-induced myocardial ischemia.