Simply put, pulmonary hypertension is an elevation in blood pressure in the lungs. While most people are aware of systemic hypertension which is usually measured by checking the blood pressure in the arms, they are unaware that there is a second blood pressure system within the chest. Pulmonary hypertension is a condition which is often overlooked until the disease is advanced. It is a condition that causes symptoms of shortness of breath/dyspnea, fatigue, and symptoms of fluid overload/heart failure.
Normal pulmonary vascular system
The pulmonary vasculature is a low pressure system much different than the rest of the blood vessels throughout the body. The left side of the heart (which pumps blood to the body) is large and muscular, generating enough pressure to push blood flow throughout your entire body. The right side of the heart, in contrast, is the smaller side of the heart, supplying a blood flow to the blood vessels in the lungs. In pulmonary hypertension (PH), the right side of the heart has to work harder and harder to pump against the increased pressure in the pulmonary arteries. Just like any muscle that is constantly worked, it grows bigger. Unfortunately, the right side of the heart can only enlarge to an extent and eventually it begins to fail if the underlying cause of the increased lung pressures are not treated. The ability for the chambers to efficiently pump blood diminishes, eventually leading to right heart failure.
Testing for Pulmonary Hypertension
Initially, a proper history and physical exam must be obtained to determine the likelihood of whether or not the patient may have elevated blood pressure in their lungs. Then, certain noninvasive tests may be employed to evaluate for the presence of pulmonary hypertension. The most common test is the echocardiogram. Blood pressure in the lungs can be estimated using the echocardiogram. In addition, a cardiopulmonary exercise test (CPET) also provides important information as to the function of the cardiopulmonary system. In this test, we are able to assess whether or not the heart has difficulty pumping blood through the lungs. This test gives further information related to the possibility of the patient having pulmonary vascular disease. The only definitive test for the presence or absence of pulmonary hypertension is the right heart catheterization. A separate blog post will be devoted to how this test is performed. I have written an article highlighting the right heart catheterization itself: http://www.phaonlineuniv.org/Journal/Article.cfm?ItemNumber=729
Different types of pulmonary hypertension
it is just as important to determine the underlying cause of the patient's pulmonary hypertension and whether or not is truly a disease of the pulmonary vasculature versus a disease of the heart versus a different type of heart/lung condition. Future blog posts will be devoted to special types of pulmonary hypertension. The diagnosis and assessment of pulmonary hypertension is further explained in an article that I co-authored: http://www.sciencedirect.com/science/article/pii/S0735109709012145