There are usually two methods to measure pulmonary arterial hypertension. One is through echocardiography to estimate, by measuring the speed of tricuspid regurgitation and then calculating the systolic pressure of the pulmonary artery through a formula. This method may overestimate or underestimate, hence its accuracy is not reliable. The gold standard is measuring pulmonary artery pressure via right heart catheterization. The downside of this gold standard is that it is an invasive procedure, which needs to be performed in a catheterization room; compared to ultrasound, it is also more costly. These are the two methods, each with its pros and cons. We need to choose based on the patient's situation.