Effect of propranolol on heart rate variability in hyperthyroidism

Citation metadata

From: BMC Research Notes(Vol. 11, Issue 1)
Publisher: BioMed Central Ltd.
Document Type: Report
Length: 1,852 words
Lexile Measure: 1570L

Document controls

Main content

Article Preview :

Author(s): Aurel T. Tankeu1,2 , Marcel Azabji-Kenfack1,2 , Chris-Nadège Nganou2,3 , Eliane Ngassam1,2 , Liliane Kuate-Mfeukeu2,3 , Camille Mba1 , Mesmin Y. Dehayem1,2 , Jean-Claude Mbanya1,2 and Eugene Sobngwi1,2

Introduction

Typical clinical signs of hyperthyroidism such as increase in heart rate, cardiac output, systolic blood pressure, myocardial contractility, the presence of tremor suggest a hyper adrenergic state and [beta]-adrenergic blocking agents ([beta]-blockers) have been used in this indication for many years as they rapidly improve signs and symptoms observed in patients with thyrotoxicosis [1-4]. Propranolol is widely used in hyperthyroidism to relieve cardiac and peripheral manifestations of thyrotoxicosis and is considered as the drug of choice in the treatment of hyperthyroidism [3, 4]. However, it has been suggested that the beneficial effect of propanolol was not related to a reduction in hormone level suggesting that they must be another mechanism of action [5]. On the other hand, thyrotoxicosis is accompanied by a sympathovagal imbalance characterized by a reduced vagal tone and a subsequent increase in sympathetic activity which may contribute to sinus tachycardia generating some cardiac signs of hyperthyroidism including increase in resting heart rate and arrhythmias [6, 7]. Reduced heart rate variability (HRV), a marker of autonomic dysfunction, predicts mortality after acute myocardial infarction and propanolol has been thought to improve recovery of parasympathetic tone in these patients, thereby reducing risk of sudden death [8]. Evidence indicates that the cardiovascular state due to vagal inhibition in patients suffering from thyroid dysfunctions is poor, an attempt should therefore be made to improve vagal tone especially in hyperthyroid subjects to achieve a stable sympathovagal and cardiovascular homeostasis [9]. Although the peripheral effects of propanolol on the metabolism of thyroid hormones such as reducing peripheral conversion of FT4 to FT3 and antagonizing the [beta]-receptor-mediated effects of catecholamines are well known, many questions on its intra-cardiac effect are still unanswered. Whether [beta] blockers, especially propanolol could influence the improvement HRV in hyperthyroidism is unknown and few data are available on the topic [10]. The purpose of this study was to investigate the effect of propranolol on HRV in patients with hyperthyroidism naive to treatment.

Main text

Methods

Setting and study population

This was a before and after study, which took place at the National Obesity Center of the Yaoundñ Central Hospital. The study population was made up of recently diagnosed patients with hyperthyroidism and naïve to antithyroid treatment. All participants fulfilled diagnosis criteria of thyrotoxicosis. Patients having evidence of cardiopulmonary disease or arrhythmia or presenting a contra-indication to beta blockers were excluded. No other medication was taken during the study period.

Procedure and investigations

The study procedure was made of an inclusion visit and three exploratory visits. All patients presenting with signs or symptoms of hyperthyroidism or referred for the management of hyperthyroidism were...

Source Citation

Source Citation   

Gale Document Number: GALE|A528602725