Abstract
Thyroid hormones (THs) are synthesized in the thyroid gland, and they circulate in the blood to regulate cells, tissues, and organs in the body. In particular, they exert several effects on the cardiovascular system. It is well known that THs raise the heart rate and cardiac contractility, improve the systolic and diastolic function of the heart, and decrease systemic vascular resistance. In the past 30 years, some researchers have studied the molecular pathways that mediate the role of TH in the cardiovascular system, to better understand its mechanisms of action. Two types of mechanisms, which are genomic and non-genomic pathways, underlie the effects of THs on cardiomyocytes. In this review, we summarize the current knowledge of the action of THs in the cardiac function, the clinical manifestation and parameters of their hemodynamics, and treatment principles for patients with hyperthyroid- or hypothyroid-associated heart disease. We also describe the cardiovascular drugs that induce thyroid dysfunction and explain the mechanism underlying the thyroid toxicity of amiodarone, which is considered the most effective antiarrhythmic agent. Finally, we discuss the recent reports on the involvement of thyroid hormones in the regulation of myocardial regeneration and metabolism in the adult heart.
Highlights
The thyroid gland secretes two thyroid hormones (THs), 3,5,3 -triiodothyronine (T3) and 3,5,3,5 −tetraiodothyronine (T4 known as thyroxine)
Recent clinical studies have reported that patients with cardiovascular disease who have reduced T3 levels have a higher risk of death from heart failure (Wang et al, 2017; Neves et al, 2019)
According to the guidelines of the European Thyroid Association, treatment for hypothyroidism is recommended for patients with severe hypothyroid disease, symptoms of hypothyroidism, an age < 70 years, and elevated risk of cardiovascular disease (CVD) (Pearce et al, 2013)
Summary
The thyroid gland secretes two thyroid hormones (THs), 3,5,3 -triiodothyronine (T3) and 3,5,3 ,5 −tetraiodothyronine (T4 known as thyroxine). Thyroid dysfunction, which causes hyperthyroidism and hypothyroidism, is associated with increased cardiovascular risk factors (Klein and Ojamaa, 2001; Rodondi et al, 2010; Collet et al, 2012). The cardiovascular effects of hypothyroidism significantly differ from those of hyperthyroidism; for example, cardiac output can be reduced by 30 to 50%, compared to that in a normal state (Danzi and Klein, 2004).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
