Ultrasonic Integrated Backscatter Cyclic Variations During Atrial Pacing in Patients with and without Coronary Artery Disease

Contraction and relaxation of normal myocardium are associated with parallel integrated backscatter cyclic variations (IB CV). It has been demonstrated that IB CV are reversibly reduced in magnitude during coronary occlusion and reperfusion. To evaluate in humans the effects of pacing-induced ischemi on IB CV, 29 pts were studied with multiplane TEE and simultaneous atrial pacing (up to 150 beats/m′). prototype (Hewlett-Packard AD system) was used to acquire and analyse IB images. In each pt transgastric 2 chamber view was acquired at rest, at peak-pacing and 5 cardiac cycles after pacing interruption (recovery). Twenty-one pts had significant coronary stenosis (≥50% narrowing): 8 pts developed myocardial ischemi (chest pain, ECG changes and wall motion abnormalities) during atrial-pacing [Group A], while the remaining 13 pts did not [Group B]. Eight pts had normal coronaries and no myocardial ischemi during pacing [Group C]. IB CV analysis was performed only in myocardial segments perpendicular to ultrasonic beam (anterior and inferior wall in transgastric view). In group and B pts only segments within territory supplied by stenotic coronary artery were considered. Results: Conclusion: atrial pacing does not affect IB CV in myocardium supplied by normal coronary arteries. During pacing, IB CV are blunted in myocardium supplied by significantly narrowed coronary arteries, even in the absence of traditional signs of ischemia. IB CV have potential in the identification of stress-induced regional left ventricular dysfunction in pts with coronary artery disease