Classifying pulmonary hypertension
Pulmonary hypertension (PH) is defined as resting mean pulmonary arterial pressure (mPAP) ≥25 mmHg, compared to a normal value less than 20 mmHg.
Classification of PH is broken into five categories by the WHO:
- Pulmonary artery hypertension, the most common category that includes hereditary/idiopathic causes, drugs & toxins, connective tissue disorders like scleroderma/SSc, HIV, and schistosomiasis
- Secondary to left heart disease, mostly heart failure with preserved ejection fraction (HFpEF)
- Secondary to chronic lung disease and/or hypoxemia, including COPD and OSA as well as interstitial lung disease
- Secondary to chronic thromboembolic pulmonary hypertension (CTEPH): fairly self-explanatory, I suppose
- Secondary to everything else: weird things that you wouldn’t necessarily think of, including sickle cell disease, other chronic hemolytic anemias, chronic kidney disease, and a grab-bag of other things
A few interesting points:
- The most common cause worldwide is schistosomiasis (included in Group 1, above)
- Longstanding PH can lead to cor pulmonale, which is not good