Diminished myocardial function can be seen in chronic coronary stenosis (CS) even in the presence of normal resting myocardial blood flow. We hypothesized that adenosine contributes to myocardial depression in this setting, predominantly through activation of the A1 adenosine receptor. To test this hypothesis we used aminophylline, a nonselective adenosine receptor antagonist, and 8-cyclopentyl 1,3 dipropylxanthine, a selective A1 adenosine receptor antagonist, in a canine model of chronic CS. Chronic CS was produced by placement of ameroid constrictors on the left anterior descending and left circumflex coronary arteries in 17 adult mongrel dogs, which resulted in severe left ventricular dysfunction 6 weeks later. Eight dogs without ameroid placement were used as controls (C). Closed-chest echocardiographic short-axis images at the low midpapillary level, hemodynamics, and radiolabeled microsphere-derived myocardial blood flow were obtained before and immediately after injection of either 5 mg/kg-1 of aminophylline (7 left ventricular dysfunction and 4 C dogs) or 1 mg/kg -1 of 8-cyclopentyl 1,3-dipropylxanthine (10 left ventricular dysfunction and 4 C dogs). Both 8-cyclopentyl 1,3-dipropylxanthine and aminophylline had no effect in C animals but resulted in a significant transient increase in regional percent wall thickening (P < .05) with a concomitant decrease in end-systolic wall stress (P < .05) in CS animals. There was no change in transmural myocardial blood flow or systemic hemodynamics to explain these results. Thus, adenosine plays a significant role in myocardial dysfunction in chronic ischemia by activation of the A 1 receptor. Aminophylline or a selective A1 adenosine receptor antagonist can be used to detect viable myocardium and may be safer than dobutamine in severe chronic ischemic heart disease.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of the American Society of Echocardiography|
|State||Published - Jul 2003|
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging
- Cardiology and Cardiovascular Medicine