Pulmonary Hypertension

Pulmonary hypertension is a rare cause of high blood pressure(hypertension) in the pulmonary artery(pulmonary artery). When the blood vessels of the lungs becomes damaged, such as in pulmonary arterial hypertension, the thickening and stiffening of the pulmonary artery walls occur which causes deviations in the vessel wall. The consequence of this is that the pressure in the pulmonary artery rises and also in the RV. PH is a pressure load on the right heart. Click here to see an animation about PH.

WHO classification

Pulmonary hypertension is classified by the World Health Organization (WHO) as the place where the obstruction lies.

Classification	Subcategories
Pulmonary Arterial Hypertension(PAH)	Idiopathic PAH(unknown cause) Familial PAH(genetic cause) PAH by underlying causes such as, connective tissue diseases, congenital heart disease, portal hypertension, HIV infection, drugs, drugs, toxins, and other factors. PAH with significant venous and/or capillary involvement Persistent pulmonary hypertension of newborn
Pulmonary hypertension with left heart disease	In disorders of left atrium and ventricle of the heart With Valvular
Pulmonary hypertension in pulmonary disease and/or hypoxemia	Chronic obstructive pulmonary disease(COPD) Interstitial lung disease Sleep disorders, alveolar hypoventilation; chronic exposure to high altitude Congenital malformations/developmental
Pulmonary hypertension due to chronic thrombotic and/or embolic processes	Thromboembolic obstruction of proximal pulmonary arteries Thromboembolic obstruction of distal pulmonary arteries Embolism of the lung (eg: tumor, parasites, foreign body, bone marrow)
Pulmonary hypertension as a result of other diseases and disorders	Sarcoidosis Histiocytosis X Lymphangioleiomyomatosis Sickle Cells Compression of the pulmonary vessels from outside(eg: by lymphadenopathy, tumor, fibrosing mediastinitis) Storage disorders

 

Evidence of pulmonary hypertension

	Unlikely	Possible	Likely
SPAP	<36 mmHg	36-50 mmHg	>50 mmHg
TR Vmax	<2.8 m/s	2.9-3.4 m/s	>3.4 m/s
AccT	>120 ms	120-60 ms	<60 ms
RV MPI (TCO-ET/ET)	<0.36
RV MPI (TDI)	<0:50

Calculations for estimating pressure in the pulmonary artery

 

	Formula
Systolic PA pressure	4 x(TR Vmax)2 + estimated RA pressure
Diastolic PA pressure	4 x(PR Ved)2 + estimated RA pressure
Mean PA pressure	0.3 x systolic PA pressure + 0.6 x diastolic PA pressure
	90 - (0.62 x ACCT) if Acct < 120ms
	4 x(PR Vmax)2 + estimated RA pressure
	TR PGmean + estimated RA pressure

Example severe pulmonary hypertension

Short acct with "systolic notch" Flattened septum

Increased Systolic PA pressure Increased MPI, extension of isovolumetric times. Source : Eur Respir Rev 2012 ; 21: 125, 239-248

References

1. Habib G, Badano L, Tribouilloy C, Vilacosta I, Zamorano JL, Galderisi M, Voigt JU, Sicari R, Cosyns B, Fox K, Aakhus S, and European Association of Echocardiography. Recommendations for the practice of echocardiography in infective endocarditis. Eur J Echocardiogr. 2010 Mar;11(2):202-19. DOI:10.1093/ejechocard/jeq004 |