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Exercise echocardiographic correlates of transient dilatation of the left ventricular cavity on exercise thallium-201
A Van Tosh1, S Hecht, M Berger
1Department of Medicine, Beth Israel Medical Center, New York, NY 10003.
Insights
Transient dilatation of the left ventricle during exercise stress tests may signal coronary artery disease. This study suggests that impaired systolic function, specifically the failure of the left ventricle to shrink during exercise, causes this observed dilatation.
Area of Science:
- Cardiology
- Nuclear Cardiology
- Echocardiography
Background:
- Transient left ventricular dilatation on exercise thallium imaging indicates significant coronary disease.
- The underlying mechanisms for this scintigraphic finding are not fully understood.
Purpose of the Study:
- To investigate the changes in left ventricular cavity size during exercise.
- To determine the mechanisms responsible for transient dilatation observed in exercise thallium imaging.
Main Methods:
- Studied 32 patients undergoing both exercise thallium perfusion imaging and exercise echocardiography.
- Assessed left ventricular cavity size using apical four-chamber view area measurements from rest to peak exercise.
- Categorized patients into those with (group 2, n=8) and without (group 1, n=24) transient dilatation.
Main Results:
- Patients without transient dilatation (group 1) showed a decrease in systolic left ventricular area from rest to exercise.
- Patients with transient dilatation (group 2) did not exhibit a decrease in systolic left ventricular area during exercise.
- No significant changes in diastolic left ventricular area were observed in either group during exercise.
Conclusions:
- Exercise-induced systolic dysfunction, characterized by a failure of the left ventricle to decrease its systolic cavity size, may be a key mechanism causing transient dilatation on scintigraphy.
- This finding highlights the importance of assessing systolic function in conjunction with perfusion imaging for diagnosing coronary artery disease.
Abstract:
Transient dilatation of the left ventricular cavity on exercise thallium perfusion imaging is recognized as a marker of significant coronary disease, but the mechanisms that produce this finding are not fully understood. We studied 32 patients who underwent exercise thallium imaging and exercise echocardiography to determine the changes in left ventricular cavity size that underlie transient dilatation. Left ventricular area from the apical four-chamber view was used to approximate left ventricular cavity size. There were 24 patients who did not have transient dilatation (group 1) and 8 patients who did have transient dilatation (group 2) on thallium imaging. Systolic area decreased from rest to exercise in group 1 patients but not in group 2 patients. There was no significant change in diastolic area from rest to exercise in either group 1 or group 2 patients. Thus, exercise-induced systolic dysfunction, manifested as a failure to decrease left ventricular systolic cavity size in exercise, may be an important mechanism in producing scintigraphic transient dilatation.