Abstract

To compare the sensitivity of dipyridamole, dobutamine and pacing stress echocardiography for the detection of myocardial ischemia we produced a physiologically significant stenosis in the left circumflex artery of 14 open-chest dogs (range: 50 to 89% reduction in luminal diameter). In each study, dobutamine (5 to 40 microg kg(-1) min(-1) in 3-min stages) and pacing (20 bpm increments, each 2 min, up to 260 bpm) were performed randomly, and then followed by dipyridamole (up to 0.84 mg/kg over 10 min). The positivity of stress echocardiography tests was quantitatively determined by a significant (P<0.05) reduction of or failure to increase absolute and percent systolic wall thickening in the stenotic artery supplied wall, as compared to the opposite wall (areas related to the left anterior descending artery). Systolic and diastolic frozen images were analyzed off-line by two blinded observers in the control and stress conditions. The results showed that 1) the sensitivity of dobutamine, dipyridamole and pacing stress tests was 57, 57 and 36%, respectively; 2) in animals with positive tests, the mean percent change of wall thickening in left ventricular ischemic segments was larger in the pacing (-19 +/- 11%) and dipyridamole (-18 +/- 16%) tests as compared to dobutamine (-9 +/- 6%) (P = 0.05), but a similar mean reduction of wall thickening was observed when this variable was normalized to a control left ventricular segment (area related to the left anterior descending artery) (pacing: -16 +/- 7%; dipyridamole: -25 +/- 16%; dobutamine: -26 +/- 10%; not significant), and 3) a significant correlation was observed between magnitude of coronary stenosis and left ventricular segmental dysfunction induced by ischemia in dogs submitted to positive stress tests. We conclude that the dobutamine and dipyridamole stress tests showed identical sensitivities for the detection of myocardial ischemia in this one-vessel disease animal model with a wide range of left circumflex artery stenosis. The pacing stress test was less sensitive, but the difference was not statistically significant. The magnitude of segmental left ventricular dysfunction induced by ischemia was similar in all stress tests evaluated.

Highlights

  • Material and MethodsStress echocardiography has become a clinically useful method for detection, prognosis and therapeutic decisions in patients with known or suspected coronary heart disease

  • This investigation was designed to compare, in an animal model of one-vessel coronary heart disease with a wide range of physiologically significant coronary stenosis: 1) sensitivity of dipyridamole, dobutamine and pacing stress echocardiography for the detection of myocardial ischemia, and 2) the magnitude of segmental left ventricular dysfunction induced by ischemia

  • The stress test was interrupted before the peak target of the experimental protocol as a consequence of 1) occurrence of A-V conduction disturbances in 13 animals during pacing, 2) ventricular (3 animals) or supraventricular arrhythmias (1 animal) induced by dobutamine, and 3) occurrence of

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Summary

Introduction

Material and MethodsStress echocardiography has become a clinically useful method for detection, prognosis and therapeutic decisions in patients with known or suspected coronary heart disease. This investigation was designed to compare, in an animal model of one-vessel coronary heart disease with a wide range of physiologically significant coronary stenosis: 1) sensitivity of dipyridamole, dobutamine and pacing stress echocardiography for the detection of myocardial ischemia, and 2) the magnitude of segmental left ventricular dysfunction induced by ischemia.

Results
Conclusion
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