What is pulmonary hypertension?
Pulmonary hypertension is nothing but high blood pressure in the blood vessels of lung (pulmonary arteries and veins). If there is no known cause it is called primary pulmonary hypertension. If there is a cause like disease of the left side of the heart, or obstructive airways disease, then it is called secondary pulmonary hypertension.
Can pulmonary hypertension be measured using the ‘BP apparatus’?
No. Pulmonary hypertension cannot be measured using the usual blood pressure measuring instrument (BP apparatus or sphygmomanometer).
How can pressure in the pulmonary arteries be measured?
In the yesteryears, blood pressure in the blood vessels of the lung could be measured only by introducing small tubes directly (catheters) into them. But now pressure in the arteries of the lung can be estimated indirectly by Doppler echocardiography. Doppler echocardiography uses ultrasound beams to measure the velocity of blood in the chambers of the heart. From the velocity of reverse blood flow from the right ventricle to right atrium (tricuspid regurgitation), pressure difference between these two chambers (upper and lower right sided chambers of the heart) can be estimated. This will give an idea of the pressure in the right ventricle. Usually pressure in the right ventricle and the pulmonary artery (main blood vessel which takes blood to the lung from the right ventricle) are the same when the right ventricle contracts (systolic pressure). To be more accurate, 10 is added to the measured gradient to get the estimated right ventricular systolic pressure (RVSP) as the normal pressure in the right atrium is about 10 mm Hg. High pressure in the pulmonary artery is known as pulmonary arterial hypertension (PAH). Blood pressure in the pulmonary veins which return oxygenated blood from the lungs to the heart cannot be measured by this technique. If blood pressure in the pulmonary veins are elevated, it is known as pulmonary venous hypertension.