Our patient's diagnosis of idiopathic pulmonary arterial hypertension is consistent with the history, bedside findings and the non-invasive laboratory assessment. Right heart catheterization can provide data essential for the diagnosis and management of the patient. The key data to obtain include pulmonary artery systolic, diastolic and mean pressures; cardiac output to calculate pulmonary vascular resistance; pulmonary capillary wedge pressure and/or the left ventricular end diastolic pressure to exclude underlying left heart disease; and evaluation of the response to vasodilators.
PPH hemodynamic data
These are the hemodynamic findings in our patient. The findings most suggestive of idiopathic pulmonary arterial hypertension include the normal capillary wedge pressure and normal left ventricular end diastolic pressure, in the presence of severely elevated pulmonary artery pressure. The elevated right atrial pressure and right ventricular end diastolic pressure reflect right ventricular diastolic dysfunction. The cardiac output is reduced and the pulmonary vascular resistance is markedly elevated, compatible with severe pulmonary vascular disease. The normal saturations that were found during catheterization exclude significant left-to-right shunt. The diagnosis of pulmonary hypertension is made by the following: mean PA pressure ≥ 25 mmHg, left ventricular end diastolic pressure or pulmonary capillary wedge pressure less than 15 mmHg, pulmonary vascular resistance greater than 3 Wood units.
Short-acting vasodilator challenge
A short-acting vasodilator challenge should also be part of the initial catheterization study. An agent with a short half-life is used to evaluate pulmonary vasodilatory response. Agents that can be used include intravenous adenosine and prostacyclin or inhaled nitric oxide. A "positive" response to the vasodilator challenge includes a reduction in pulmonary artery pressure accompanied by an increase in cardiac output and little or no change in systemic blood pressure. Specifically, the mean pulmonary artery pressure should decrease by greater than 10 mmHg and decrease to below 40 mmHg. A "positive" response to the challenge predicts those patients who will benefit from a long-acting oral vasodilator.
Our patient
During initial catheterization, our patient had no response to the vasodilator challenge with prostacyclin.