​

PULMONARY ARTERIAL HYPERTENSION (PAH)

Definition: A condition with increased blood pressure within the arteries of the lungs. Normally the mean pulmonary arterial pressure is about 15mmHg.

The Pulmonary Arterial Systolic and Diastolic pressures are about 25 & 10 mg Hg respectively.

In Pulmonary Hypertension (PH) the mean Pulmonary Artery Pressure (PAP) is equal to or more than 20mmHg.

 

ETIOLOGY

A combination of heart and/or lung disease causes PAH. For instance, rheumatic heart disease with mitral stenosis leads to PAH.

In cardiac disease, there is an increase in left atrial pressure, leading to an increased pulmonary capillary wedge pressure of <15. Normally this is <12.

Diagnostic tools include EKG and catheterization. Echo cardiograms are useful too.

 

CLASSIFICATION OF PH

 

• PAH- Primary Pulmonary Hypertension

Idiopathic; with vast-reactivity; inherited PAH; drugs and toxin induced; associated with connective tissue disease, infections, portal hypertension, and schistosomiasis; and PAH with venous/capillary involvement

 

• PH DUE TO LEFT HEART DISEASE

Heart failure with preserved Ejection Fraction (EF); heart failure with reduced EF; & Valvular heart disease.

 

• PH DUE TO LUNG DISEASES AND/OR HYPOXIA

Obstructive lung disease; restrictive lung disease; mixed etiology lung disease; and hypoxia without lung disease. A pO2 value of as low as 51 is not unusual.

 

• PH DUE TO PULMONARY ARTERY OBSTRUCTION

Chronic thromboembolic PH; Other pulmonary obstructions

 

• PH WITH UNCLEAR MECHANISMS

  • Hematologic disorders; Systemic disorders – such as  Sarcoidosis.

  • Chronic pulmonary emboli, which cause obstruction of the pulmonary artery, can be cured surgically at social centers like the UCSD unit.

 

HISTORY AND PHYSICAL, AND DIAGNOSTIC TESTS

History presentation includes: Dyspnea, fatigue, chest pain, edema, syncope, dizziness, cough and palpitations.

 

• Exam. For PH shows:  Loud P2 sound; RV lift, systolic murmur, early systolic click, mid-systolic ejection murmur and diastolic murmur.

• Exam, for RV Failure shows:  Jugular Venous intension, RV S3 and S4 sounds, pulsatile liver, hepatomegaly, edema, ascites and low BP.

• The PAH/PH occurs due to the thickening of the arterioles in the lungs, leading to pulmonary vascular resistance.

• The vessels have to be occluded at >60% for presentation of symptoms. Cardiac output is decreased and R ventricular failure occurs.

• Echocardiogram is a good screening tool. A perfusion scan of the lungs is a useful study.

• Fibrin tissue within the vasculature, causing obstruction, can be surgically extracted with dramatic results.

 

ADVERSE FACTORS LEADING TO INCREASED MORTALITY

CLINICAL FACTORS

Elderly age, female gender, obesity, uncontrolled systemic hypertension, diabetes mellitus, hyperlipidemia, coronary artery disease, valvular heart disease, cardiomyopathies and sleep apnea.

 

RADIOLOGY

Pulmonary sculpture congestion with KB lines, pulmonary edema, and pulmonary effusion.

 

EKG FINDINGS

Lack of Right Axis Deviation, Lack of right atrial enlargement or RVH, Left atrial enlargement and left ventricular hypertrophy.

 

THREE PATHWAYS OF APPROIVED THERAPIES FOR PAH

1. PAH is often considered to be driven by vasoconstriction.

2. A profound remodeling of the vascular wall mainly contributes to the pathogenesis of PAH.

3. New medicines seek to ameliorate the intimal fibrosis, endothelial cell proliferation, medial thickening and smooth muscle cell hypertrophy and hyperplasia seen in the pulmonary vasculature of patients with PAH.

4. Novel compounds have been introduced that target the three key pathways involved in the development and progression of PAH, namely: the endothelin (ET), nitric oxide (NO) and prostacyclin (PGI2) pathways.

 

Summarized by:

Dr. Parvin D. Syal