PH vs. PAH

Is there a difference between pulmonary hypertension (PH) and pulmonary arterial hypertension (PAH)?

Reviewing PAH DiagnosisYes, there is a difference between pulmonary hypertension (PH) and pulmonary arterial hypertension (PAH). Pulmonary arterial hypertension (PAH) is a specific subgroup of pulmonary hypertension (PH). The definition of PH is more inclusive than the definition of PAH, meaning that the specific hemodynamic measurements used to define PAH do not apply to PH.

Pulmonary hypertension (PH) is simply an elevation in the pressure in the arteries of the lungs. Many diseases such as obstructive sleep apnea (OSA), lung diseases, diastolic heart failure, and diseases of the left heart can cause the pressures in the pulmonary arteries to rise but this does not mean you have pulmonary arterial hypertension (PAH). Pulmonary arterial hypertension is a disease of the blood vessels of the lungs meaning these vessels have changed causing the elevation in pressure. In pulmonary hypertension, the elevation of the pressures is caused by another disease, the blood vessels themselves are not the problem.

WHO groups of pulmonary arterial hypertension

The World Health Organization (WHO) has grouped PH into 5 groups.  These groups are used to help distinguish PH versus PAH.  These five pulmonary hypertension WHO groups are outlined below.

1.  Pulmonary Arterial Hypertension

2.  Pulmonary Hypertension due to left heart disease

3.  Pulmonary Hypertension due to lung disease

4.  Pulmonary Hypertension due to chronic blood clots: CTEPH

5.  Pulmonary Hypertension due to miscellaneous diseases

 WHO group 1 PAH

WHO group 1 pulmonary arterial hypertension is the “true” PAH and makes up only a small portion of all pulmonary hypertension cases.  The first group can further be broken down into idiopathic pulmonary arterial hypertension, PAH related to drugs and toxins, and PAH associated with other diseases such as connective tissue disease, congenital heart disease, liver disease, HIV infection, chronic hemolytic anemias and hemoglobinopathies, and schistosomiasis.   Persistent pulmonary hypertension of the newborn and pulmonary capillary disorders are also included in WHO group 1.

Are the treatments for pulmonary hypertension different than the treatments for pulmonary arterial hypertension?

It is important to distinguish between pulmonary hypertension and pulmonary arterial hypertension because treatments used for pulmonary arterial hypertension will not help and may even harm patients that do not have PAH. The treatment for pulmonary hypertension is to treat whichever disease is causing the elevation of pressures. For example, if the patient has severe sleep apnea causing the elevation in pulmonary artery pressures, they will be prescribed therapy such as a CPAP mask and machine. Once the sleep apnea is adequately treated, the pressures in their pulmonary arteries will most likely have decreased. While some tests such as echocardiograms may estimate the pulmonary artery pressures are elevated, the right heart catheterization is the only definitive test to officially diagnose pulmonary arterial hypertension (PAH).


Pulmonary hypertension is commonly used instead of pulmonary arterial hypertension

Because the phrase pulmonary arterial hypertension is long and pulmonary hypertension is a bit shorter the phrase pulmonary hypertension is often used in place of pulmonary arterial hypertension. Once the official diagnosis of pulmonary arterial hypertension is made your physician may still call it pulmonary hypertension. The phrases pulmonary hypertension, PH, pulmonary arterial hypertension, and PAH are used interchangeably on this site and in many publications related to pulmonary hypertension.