[Thyroid hormone and the cardiovascular system]

Area of Science:

• Cardiovascular endocrinology
• Thyroid hormone signaling

Context:

• Thyroid hormones (TH) exert profound effects on the cardiovascular system via genomic and nongenomic pathways.
• TRalpha1 is the predominant thyroid hormone receptor in cardiac tissue.
• TH regulate cardiomyocyte proliferation, cardiac function, and vascular tone.

Purpose:

• To elucidate the multifaceted roles of thyroid hormones in cardiovascular physiology and pathology.
• To highlight the clinical implications of thyroid hormone imbalances in cardiovascular disease.
• To explore therapeutic strategies targeting thyroid hormone receptors.

Summary:

• Hyperthyroidism leads to a hyperdynamic cardiovascular state with enhanced cardiac function, while hypothyroidism causes opposite effects.
• TH modulate peripheral vascular resistance, the renin-angiotensin system (RAS), blood volume, and erythropoiesis, impacting cardiac preload and output.
• TH influence cardiac electrophysiology, lipid profiles, and possess protective effects against myocardial ischemic injury and cardiac remodeling.

Impact:

• TH are critical for maintaining cardiovascular homeostasis; imbalances contribute to various cardiac conditions.
• Low T3 syndrome is prevalent in acute and chronic cardiac diseases, underscoring TH's importance.
• Targeting specific thyroid hormone receptors (e.g., TRbeta1) offers potential therapeutic avenues for dyslipidemia and cardiovascular complications.