The thyroid, a small gland in the neck, influences many functions, including growth, heart rate and blood pressure. Thyroid disorders can have serious consequences for the body, including the heart. For example:

• Hypothyroidism (underactive thyroid) may increase the risk of cholesterol problems, heart attack, enlarged heart (cardiomegaly) and heart failure.
  
  
• Hyperthyroidism (overactive thyroid) may increase the risk of rapid heart rate, atrial fibrillation and cardiac arrest.

Signs and symptoms of thyroid disorders may vary from person to person and depend on the type of thyroid disorder present. Sometimes patients experience no symptoms at all. Common heart-related symptoms of thyroid disorders include bradycardia (slow heart rate), tachycardia (fast heart rate), shortness of breath, high blood pressure and angina (cardiac chest pain).

Diagnosis of thyroid disorders involves a physical examination, medical history and thyroid blood tests. In some cases, additional tests may be performed such as a thyroid scan, biopsy, chest x-ray and electrocardiogram.

Treatment methods depend on the type of thyroid disorder present. For example, the goal of treating hypothyroidism and hyperthyroidism is to restore normal levels of thyroid hormones in the body. In most cases, this is achieved with medications. In other cases, thyroid surgery may be recommended.