Pulmonary artery hypertension is defined as having at least ONE of the following:
- PA systolic pressure > 35mmHg
- Mean PA pressure > 25mmHg at rest
- Mean PA pressure > 30mmHg during exercise
According to the 2009 Fourth World Symposium on Pulmonary Hypertension, the exercise criteria should be abandoned and only a mean PA of > 25 mmHg at rest should be considered as defining pulmonary hypertension.
Editorial/Summary of new Guidelines, see Ref. 1. Original article referenced in editorial, see Ref. 2
Primary pulmonary hypertension is a diagnosis of exclusion; it is much less common than secondary pulmonary hypertension.Secondary pulmonary hypertension has many possible etiologies. These include :
The most common cause of elevated PA pressures in adults with acquired heart disease is left atrial hypertension. This is most commonly due to: mitral valve disease, LV diastolic dysfunction, LV systolic dysfunction, or loss of AV synchrony.
(Acute: PA diastolic and occlusion pressure similar to LA pressure; chronic: PA diastolic pressure greater than PA occlusion pressure, which is similar to LA pressure)
Pulmonary venous obstruction. For example, a pulmonary embolism.
(Associated with increased transpulmonary gradient (meanPAP-LAP) and increased PVR.)
Pulmonary vascular occlusive disease. This vascular bed fibrosis develops after chronic exposure to high flow or high pressure in the pulmonary arteries.
(PA diastolic pressure much higher than PA occlusion pressure. Also, increased transpulmonary gradient and PVR).
Large left-to-right shunt, usually a VSD. Elevated PA pressures may be due to a high flow into the PA, or they may be secondary to high pulmonary resistance despite normal flows.
(PA diastolic and occlusion pressures are similar to LA pressure)
Hypoventilation. Examples include : obesity, Pickwickian syndrome.
Misc: IV drug use, high altitudes.
M M Hoeper The new definition of pulmonary hypertension. Eur. Respir. J.: 2009, 34(4);790-1
G Kovacs, A Berghold, S Scheidl, H Olschewski Pulmonary arterial pressure during rest and exercise in healthy subjects: a systematic review. Eur. Respir. J.: 2009, 34(4);888-94