Pulmonary hypertension (PH) is a broad topic encompassing primary and secondary etiologies. Similar to systemic hypertension, PH refers to elevated pressures in the pulmonary vessels. It’s important to understand how PH is classified and which specific vessels are involved: pulmonary arteries → pulmonary capillaries → pulmonary veins.
PRE-capillary PH refers to elevated pulmonary ARTERIAL pressures and POST-capillary refers to elevated pulmonary VENOUS hypertension. For example, it makes sense that WHO Group 2 PH (caused by left heart issues) will initially increase pulmonary venous pressures as blood flow is directed backwards. In reality, many patients with PH have both arterial and venous issues.
Symptoms can initially be fairly nonspecific and include exertion dyspnea and fatigue. As the severity worsens, signs of overt right heart failure may predominate. The history/physical exam in combination with echocardiography, labs, EKG, and especially cardiac catheterization can help hone in on the diagnosis. The functional classification helps me ascertain the day-to-day limitations a patient’s PH has incurred to help me gauge how “sick” they might be in the ICU or OR when faced with other clinical situations (septic shock, complex cardiac surgeries, etc.)
I created this table to outline the classification system for PH. Share this with colleagues, drop me a comment below with questions, and let me know what you think!