Alterations in ultrasonic backscatter during exercise-induced myocardial ischemia in humans

Dino F. Vitale, Robert O. Bonow, Giusto Gerundo, Nicola Pelaggi, Gianfranco Lauria, Dario Leosco, Fernando Coltorti, Carlo Bordini, Carlo Rengo, Franco Rengo

Research output: Contribution to journalArticle

Abstract

Background: Experimentally induced myocardial ischemia in animals causes tissue modifications that alter characteristics of the ultrasonic beam backscattered from the myocardial muscle. Alterations of backscatter parameters have been evidenced in human subjects with acute or remote myocardial infarction and during ischemia induced by angioplasty balloon occlusion or pharmacological stimuli. The effects of transient effort ischemia in humans have not been reported. The purpose of this study is to assess ultrasonic backscatter parameter changes induced by transient effort myocardial ischemia in human subjects. Methods and Results: Nineteen patients with single left anterior descending coronary stenosis and 15 healthy subjects underwent ultrasonic backscatter analysis (parasternal long-axis view) at rest, immediately after a supine stress test, and 30 minutes later. Two windows were selected in each ultrasonic study: one encompassing the septum; the other, the posterior wall. Integrated backscatter was computed throughout the cardiac cycle, yielding a power curve relative to the midmyocardial region of the myocardial wall (excluding pericardial and endocardial borders). Five parameters were computed from the backscatter power curve: the maximum minimum difference, amplitude and phase of the first harmonic Fourier fitting, phase-weighted amplitude, and time-averaged integrated backscatter difference from rest (an index of overall myocardial reflectivity). This protocol allowed comparison of the backscatter data from a region at risk of ischemia (the septum) with that from a region normally perfused (posterior wall) and a comparison with the same regions of the control group during the three ultrasonic studies. All backscatter indexes in the septum were altered significantly by exercise compared with rest values, whereas no changes were found in the normally perfused posterior wall or in the septum of the control group. All modified parameters returned to baseline values at the time of the recovery study. Conclusions: These data indicate that transient, exercise-induced ischemia is associated with reduction of the cardiac cycle-dependent variation of the integrated backscatter power curve, a temporal shift in the nadir of the power curve with respect to the R wave (phase increase), and a small but detectable increase of myocardial reflectivity. These changes may be detected noninvasively in humans with ultrasonic backscatter analysis.

Original languageEnglish
Pages (from-to)1452-1457
Number of pages6
JournalCirculation
Volume92
Issue number6
Publication statusPublished - Sep 15 1995

Keywords

  • echocardiography
  • ischemia

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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    Vitale, D. F., Bonow, R. O., Gerundo, G., Pelaggi, N., Lauria, G., Leosco, D., Coltorti, F., Bordini, C., Rengo, C., & Rengo, F. (1995). Alterations in ultrasonic backscatter during exercise-induced myocardial ischemia in humans. Circulation, 92(6), 1452-1457.