Left ventricular function at rest and during exercise in acute hypothyroidism.

Abstract

SUMMARY The effect of hypothyroidism on left ventricular function at rest and during exercise was studied in nine patients without demonstrable cardiovascular disease who had had total thyroidectomy and ablative radioiodine treatment for thyroid cancer. Radionuclide ventriculography and simultaneous right heart catheterisation were performed while the patients were hypothyroid two weeks after stopping triiodothyronine treatment (to permit routine screening for metastases) and while they were euthyroid on thyroxine replacement treatment. When the patients were hypothyroid, cardiac output, stroke volume, and end diastolic volume at rest were all lower and peripheral resistance was higher than when they were euthyroid. Pulmonary capillary wedge pressure, right atrial pressure, heart rate, left ventricular ejection fraction, and the systolic pressure:volume relation of the left ventricle, which was used as an estimate of the contractile state, were not significantly different when the patients were hypothyroid or euthyroid. During exercise, heart rate, cardiac output, end diastolic volume, and stroke volume were higher when the patients were euthyroid than when they were hypothyroid. Again, pulmonary capillary wedge pressure, ejection fraction, and the systolic pressure:volume relation were similar in both thyroid states.The data suggest that the alterations in cardiac performance seen in short term hypothyroidism are primarily related to changes in loading conditions and exercise heart rate; they do not suggest that acute thyroid hormone deficiency has a major effect on the contractile properties of the myocardium.Thyroid hormone deficiency is known to affect the heart.`13 Although exercise intolerance is a classic feature of hypothyroidism, most studies have focused on the contractile function of the heart at rest' and little attention has been paid to the performance of the left ventricle during exercise.Some radionuclide studies assessed the response of the ejection fraction to stress in hypothyroid patients.7' The ejection fraction is widely accepted as a useful measure of ventricular performance'0 but it has limitations. Because it is the ratio of two physiological variables the size of the left ventricular chamber can change considerably without causing a significant change in ejection fraction. So the Requests for reprints to Dr Siegfried Wieshammer, Cardiology Section, Department of Internal Medicine, University of Ulm, Steinhovelstraf3e 9, D-7900 Ulm, Federal Republic of Germany.Accepted for publication 9 November 1987 haemodynamic consequences of hypothyroidism are only incompletely evaluated by the response of the ejection fraction to stress, and for a more comprehensive assessment left ventricular volumes and pressures must be measured. More importantly, the ejection fraction is dependent not only on the intrinsic contractile state of the heart but also on the preload and afterload." Changes in loading conditions seem to be especially important when thyroid function is abnormal'2 and, therefore, it is u...

Short-term hypothyroidism after Levothyroxine-withdrawal in patients with differentiated thyroid cancer: clinical and quality of life consequences

“…Short-term hypothyroidism may worsen diastolic function as a result of altered calcium handling induced by thyroid hormone deficiency. Left ventricular mass was higher in DTC patients after 5 weeks of LT4-withdrawal than during TSH-suppression; this increase was attributed to the presence of early interstitial myxedema (23). Compared with controls, diastolic dysfunction, defined by ventricular filling, was altered in patients with shortterm hypothyroidism as documented by Doppler-echocardiographs (24).…”

“…The similar pattern of these cardiovascular abnormalities in subclinical and overt hypothyroidism suggests that there is a continuum in cardiovascular effects related to thyroid hormone deficiency and also that a lesser degree of thyroid hormone deficiency may induce severe cardiovascular abnormalities. Moreover, cardiovascular function was found to be impaired not only in long-standing but also in short-term hypothyroidism (20)(21)(22)(23)(24)(25)(26)(27)(28)(29).…”

Effects of Chronic Nitrate Therapy on Left-Ventricular Volume in Patients with Heart Failure Secondary to Coronary Disease Already Treated with Captopril: A Withdrawal Study

“…Saline injections were started at end exhalation [8]. The radionuclide techniques have been described previously [9, 10]. Derived variables were calculated as follows: Stroke volume = cardiac output/heart rate; left-ventricular end-diastolic volume = stroke volume/radionuclide ejection fraction; left-ventricular end-systolic volume = end-diastolic volume – stroke volume.…”

Endocrine Disorders and the Heart

“…449,475 Although cardiac enlargement is typical, overt CHF is uncommon. [476][477][478][479] When it occurs, CHF is caused by dilated cardiomyopathy. 471 Another important cause of cardiomegaly in hypothyroidism is pericardial effusion, which occurs in up to 30% of hypothyroid patients.…”