What is pulmonary hypertension? What is a vasoactive drug study?

A right heart catheterization is an important test that is performed to measure the pressures inside the right side of your heart. More importantly, it is done to check for the presence of pulmonary hypertension.

In patients who have severe heart failure, the pulmonary artery pressure (pressure in the lung arteries) can become elevated due to the chronic congestion in the heart and lungs. This is known as pulmonary hypertension and essentially is high blood pressure in the arteries that supply the lungs. The right heart catheterization (using a Swan-Ganz catheter) can precisely measure and record this pressure. These pressures are also referred to as your hemodynamics.

If your right heart catheterization demonstrates pulmonary hypertension, the cardiologist may need to consider additional testing during your catheterization. This is referred to as a vasoactive drug study. If the pulmonary pressures are too high, special intravenous medications (vasoactive drugs) are given to try to lower the pulmonary pressures or to increase the forward pumping force of the heart (the cardiac output). They are called vasoactive because they typically work by acting on the blood vessels in the body, typically dilating (enlarging) them, which can act to lower the pressure in the arteries. This may reduce the pulmonary artery pressure and may increase the cardiac output of the heart.

These vasoactive medicines are given slowly according to a standardized administration protocol. At each stage of the protocol, careful measurements of the hemodynamics are repeated and measured. Usually, the pulmonary pressures eventually come down with escalating doses of the medicines, and the test may then be concluded. It the pressures do come down, then the person’s pulmonary hypertension is deemed “reversible.”

If a patient’s pulmonary pressures do not decrease/ improve with the special intravenous medicines during the drug study and still remain too high, their pulmonary hypertension is deemed to be “fixed” or “irreversible.” This situation is a major concern, because when a patient develops fixed pulmonary hypertension, there is a significant risk that a new transplanted heart will not function properly in their chest, and the new heart may fail shortly after the transplantation. If this is the case, these patients may not be eligible to receive a heart transplant.

Fixed pulmonary hypertension is a contraindication to transplantation because of the high risk of posttransplant failure. While you are on the heart transplant waiting list, you will undergo periodic right heart catheterizations to exclude this type of pulmonary hypertension. If pulmonary hypertension is present, then a vasoactive drug study will be performed to demonstrate that it remains reversible. As long as it remains reversible, you are still eligible for a heart transplant.