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Stress echocardiography in hyperthyroidism.
G J Kahaly1, S Wagner, J Nieswandt
1Department of Endocrinology/Metabolism, Gutenberg University Hospital, Mainz, Germany. kahaly@endokrinologie.klinik.uni-mainz.de
The Journal of Clinical Endocrinology and Metabolism
|July 15, 1999
Summary
Hyperthyroidism impairs cardiovascular function during exercise, reducing exercise capacity and cardiac reserves. These deficits are reversible with treatment, as shown by stress echocardiography.
Area of Science:
- Cardiology
- Endocrinology
- Exercise Physiology
Background:
- Hyperthyroidism frequently presents with exertional symptoms.
- Stress echocardiography is a noninvasive tool to assess exercise capacity and left ventricular function.
Purpose of the Study:
- To evaluate stress-induced cardiovascular function changes in hyperthyroidism using exercise echocardiography.
- To compare cardiovascular responses during hyperthyroidism, propranolol treatment, and after euthyroidism restoration.
Main Methods:
- Exercise echocardiography was performed on 42 untreated thyrotoxicosis patients and 22 healthy controls.
- Patients underwent testing during hyperthyroidism, after propranolol, and after achieving euthyroidism.
- A continuous ramp protocol ergometry was used, starting at 20 watts/min.
Main Results:
- Hyperthyroidism showed increased resting stroke volume index, ejection fraction, and cardiac index, but blunted exercise responses.
- Maximal workload, heart rate, and stroke volume index changes were reduced in hyperthyroidism.
- Systemic vascular resistance was reduced at rest in hyperthyroidism but did not decline further with exercise.
Conclusions:
- Stress echocardiography reveals impaired chronotropic, contractile, and vasodilatory cardiovascular reserves in hyperthyroidism.
- These impairments are reversible upon restoration of euthyroidism.
- Propranolol treatment improved stroke volume index response during exercise.