Thyroid disease and heart

  Thyroid disease and heart

Richard N, Fogoros reported that for people with almost any type of heart disease, disorders of the thyroid gland can worsen old cardiac symptoms or cause new ones, and can accelerate the underlying heart problem. This is why it is useful for those with heart disease to know a little about the cardiac effects of thyroid disease.

Hypothyroidism and the heart

In hypothyroidism the heart muscle is weakened in both its contraction phase, and also its relaxation phase. This means that the heart cannot pump as vigorously as it should, and the amount of blood it ejects with each heart beat is reduced. In addition, because the heart muscle does not relax normally in between heart beats, a potentially serious condition called diastolic dysfunction may result. Furthermore, hypothyroidism reduces the amount of nitric oxide in the lining of the blood vessels, causing them to stiffen.

Cardiac symptoms of hypothyroidism

Common symptoms include:

·         Shortness of breath on exertion and poor exercise tolerance.

·         Slow heart rate (bradycardia.) The heart rate is modulated by thyroid hormone, so that in hypothyroidism the heart rate is typically 10 - 20 beats per minute slower than normal.

·    Diastolic hypertension bcz the arteries are stiffer in hypothyroidism, which causes the diastolic blood pressure to rise.

·         Worsening of heart failure, or the new onset of heart failure.

·         Edema (swelling.) Swelling can occur as a result of worsening heart failure.

·         Hypothyroidism itself can produce a type of edema called myxedema, caused by an accumulation of abnormal proteins and other molecules in the interstitial fluid (fluid external to the body's cells.)

·         Worsening of coronary artery disease. While the reduction in thyroid hormone can actually make angina less frequent in patients who have angina, the increase in LDL-C (bad cholesterol) and in C-reactive protein seen with hypothyroidism can accelerate any underlying coronary artery disease.

Hyperthyroidism and the heart

In hyperthyroidism, caused by the overproduction of thyroid hormone, the heart muscle is "whipped" like a horse, and for a person with heart disease it's like whipping a tired horse. Thyroid hormone increases the force of contraction of, and the amount of oxygen demanded by, the heart muscle. It also increases the heart rate. For these reasons the work of the heart is greatly increased in hyperthyroidism. Hyperthyroidism increases the amount of nitric oxide in the lining of the blood vessels, causing them to dilate and become less stiff.

Cardiac symptoms of hyperthyroidism

Common symptoms include:

·         Fast heart rate (tachycardia) and palpitations.

·         Systolic hypertension. The forceful cardiac contraction increases the systolic blood pressure, though the increased relaxation in the blood vessels reduces the diastolic blood pressure.

·         Shortness of breath on exertion. This can be due to the skeletal muscle weakness cause by hyperthyroidism, or to a worsening in heart failure.

·         Heart failure. Hyperthyroidism itself can produce heart failure, but this condition is relatively rare.

·         Worsening angina. Patients with coronary artery disease often experience a marked worsening in symptoms with hyperthyroidism. These can include an increase in chest pain (angina) or even a heart attack.