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Alterations in Ultrasonic Backscatter During Exercise-Induced Myocardial Ischemia in Humans
- Source :
- Scopus-Elsevier
- Publication Year :
- 1995
- Publisher :
- Ovid Technologies (Wolters Kluwer Health), 1995.
-
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.
- Subjects :
- Adult
Male
medicine.medical_specialty
Pathology
Supine position
Myocardial Ischemia
Ischemia
Electrocardiography
Physiology (medical)
Internal medicine
Occlusion
medicine
Humans
Myocardial infarction
Exercise
medicine.diagnostic_test
business.industry
Vascular disease
Middle Aged
medicine.disease
Echocardiography
Parasternal line
Cardiology
Female
Ultrasonic sensor
Cardiology and Cardiovascular Medicine
business
Subjects
Details
- ISSN :
- 15244539 and 00097322
- Volume :
- 92
- Database :
- OpenAIRE
- Journal :
- Circulation
- Accession number :
- edsair.doi.dedup.....ee1fce7b9c478aa8cb00712316a44f7a