July 23, 2016
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Pulmonary Hypertension (cont.)

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How is pulmonary hypertension defined?

When the heart pumps blood it is referred to as systole, and when the heart fills with blood it is referred to as diastole. Normal pulmonary artery pressures range from an upper pressure (systolic) of 15-30 mmHg and a lower pressure (diastolic) of 4-12 mmHg. These values can be obtained approximately by and ultrasound of the heart (echocardiogram), and more accurately using a catheter to measure the pressures in the pulmonary circulation (right heart catheterization).

What is pulmonary hypertension?

The right ventricle pumps blood returning from the body into the pulmonary arteries to the lungs to receive oxygen. The pressures in the lung arteries (pulmonary arteries) are normally significantly lower than the pressures in the systemic circulation. When pressure in the pulmonary circulation becomes abnormally elevated, it is referred to as pulmonary hypertension. This most commonly occurs when the pulmonary venous pressure is elevated, so called pulmonary venous hypertension (PVH). This pressure is transmitted back to the right side of the heart and the pulmonary arteries. The result is elevated pulmonary pressure throughout the pulmonary circulation. Some of this is a direct pressure transmission from the venous system backward and some can result from a reactive constriction of the pulmonary arteries.

Less commonly, pulmonary hypertension results from constriction, or stiffening, of the pulmonary arteries that supply blood to the lungs, so called pulmonary arterial hypertension (PAH).

Whether it is pulmonary venous or pulmonary arterial hypertension, it becomes more difficult for the heart to pump blood forward through the lungs. This stress on the heart leads to enlargement of the right heart and eventually fluid can build up in the liver and other tissues, such as the in the legs.

What are pulmonary arteries?

  • The human body has two major sets of blood vessels that distribute blood from the heart to the body. One set pumps blood from the right heart to the lungs, and the other from the left heart to the rest of the body (systemic circulation). When a doctor or a nurse measures the blood pressure on a person's arm, he/she is measuring the pressures in the systemic circulation. When these pressures are abnormally high, the person is diagnosed as having high blood pressure (systemic hypertension).
  • The portion of the circulation that distributes the blood from the right side of the heart to the lungs and back to the left side of the heart is referred to as the pulmonary (lung) circulation.
Medically Reviewed by a Doctor on 3/30/2016

Source: MedicineNet.com
http://www.medicinenet.com/pulmonary_hypertension/article.htm

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