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Effects of thyroid hormone and thyroid dysfunction on the cardiovascular system
R D Kienle1, D Bruyette, P D Pion
1Department of Medicine, School of Veterinary Medicine, University of California, Davis.
Summary
Thyroid disease impacts canine and feline cardiovascular systems. While hypothyroidism rarely causes heart issues, hyperthyroidism can lead to heart failure, but both are reversible.
Area of Science:
- Veterinary Cardiology
- Endocrinology
Background:
- Thyroid hormones significantly influence cardiovascular function in animals.
- Both deficiencies (hypothyroidism) and excesses (hyperthyroidism) can alter heart and vascular function.
- Cardiovascular changes stem from direct myocardial effects and indirect vascular/tissue effects.
Purpose of the Study:
- To summarize the cardiovascular manifestations of thyroid disease in veterinary medicine.
- To differentiate the cardiac impacts of hypothyroidism and hyperthyroidism.
- To highlight the reversibility of thyroid-related cardiovascular changes.
Main Methods:
- Review of clinical observations and echocardiographic findings in animals with thyroid dysfunction.
- Analysis of the physiological effects of thyroid hormones on the cardiovascular system.
- Correlation of clinical signs with specific thyroid hormone levels.
Main Results:
- Hypothyroidism infrequently causes clinically significant cardiovascular abnormalities, mainly reduced left ventricular function or arrhythmias.
- Hyperthyroidism, common in cats, frequently causes dramatic cardiovascular changes, including hyperdynamic systolic function and myocardial hypertrophy.
- These changes can progress to congestive or high-output heart failure.
- In most cases, cardiovascular abnormalities associated with thyroid dysfunction are reversible upon achieving a euthyroid state.
Conclusions:
- Thyroid disease significantly affects animal cardiovascular health.
- Hyperthyroidism presents a greater risk for severe cardiac manifestations than hypothyroidism.
- Prompt diagnosis and treatment to restore euthyroid state are crucial for cardiovascular recovery.