Improvement by isosorbide dinitrate of exercise-induced regional myocardial dysfunction

Area of Science:

• Cardiology
• Pharmacology
• Animal Models

Background:

• Chronic single-vessel coronary heart disease can impair regional myocardial function.
• Developing collateral circulation is a compensatory mechanism in coronary obstruction.
• Exercise can exacerbate functional deficits in ischemic heart regions.

Purpose of the Study:

• To evaluate the efficacy of isosorbide dinitrate in preventing exercise-induced myocardial dysfunction.
• To assess the impact of isosorbide dinitrate on hemodynamic parameters and regional function in an animal model of coronary heart disease.

Main Methods:

• Sonomicrometry was used in conscious dogs to measure regional segment length and dynamic wall thickness via telemetry.
• An ameroid constrictor was implanted to create a chronic ischemic zone supplied by the left circumflex coronary artery.
• Exercise tests were performed before and after oral isosorbide dinitrate administration.

Main Results:

• Exercise increased hemodynamic parameters and segment shortening in normal myocardial regions.
• Isosorbide dinitrate reduced increases in left ventricular pressures and end-diastolic dimensions during exercise.
• Percent wall thickening and segment shortening in the ischemic zone did not significantly deteriorate with isosorbide dinitrate during exercise.

Conclusions:

• Isosorbide dinitrate effectively prevents exercise-induced deterioration of regional myocardial function in a canine model of chronic coronary heart disease.
• This study suggests isosorbide dinitrate may be beneficial in managing patients with single-vessel coronary disease experiencing exertional ischemia.