Pulmonary Hypertension


Definition:

An elevation in pulmonary vascular pressure that can be caused by an isolated increase in pulmonary arterial pressure / by increase in both pulmonary arterial & pulmonary venous pressure.
In practice, pulmonary HTN is used for pulmonary arterial HTN & is defined as a resting mean pulmonary artery pressure greater than 25mmHg / a resting systolic pulmonary artery pressure greater than 40mmHg.

Etiology & Classification of Pulmonary HTN

  1. Pulmonary arterial HTN
    -Sporadic.
    -Familial.
    -Related to collagen vascular disease, liver cirrhosis, HIV infection, congenital systemic to pulmonary shunts.
    -Associated with significant venous / capillary involvement.
    -Pulmonary veno-occlusive disease.
Pulmonary HTN
Pulmonary HTN

2. Pulmonary venous HTN
-Left sided atrial / ventricular heart disease.
-Left sided valvular heart disease.

3. Pulmonary HTN associated with hypoxemia
-COPD.
-Interstitial lung disease.
-Obstructive sleep apnea

4. Pulmonary HTN due to chronic thrombotic / embolic disease
-Thromboembolism to proximal pulmonary arteries.
-Obstruction of distal pulmonary arteries in pulmonary embolism, sickle cell disease.

5. Miscellaneous
-Sarcoidosis, histiocytosis X.

Pathophysiology of Pulmonary HTN

-Normal pulmonary artery systolic pressure at rest is 18-25mmHg, with a mean of 12-16mmHg. This low pressure is due to large cross-sectional area of pulmonary circulation, which results in low resistence.
-Increase in pulmonary vascular resistence.
-Increase in pulmonary blood flow.

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Clinical Feature of Pulmonary HTN

Symptoms of pulmonary HTN

-Fatigue, dyspnea, syncope, angina due to reduced cardiac output.
-Hemoptysis uncommon & occurs due to rupture of distended pulmonary vessels.
-Peripheral edema, tender hepatomegaly, raised jugular venous pressure due to right ventricle failure.

2) Signs of pulmonary HTN
-Cyanosis
Peripheral cyanosis due to reduced cardiac output & skin blood flow.
-Pulse is low volume due to reduced cardiac output & left ventricle stroke volume.
-JVP (jugular venous pressure)
Prominent a waves, JVP elevated with right ventricle failure, prominent v waves & rapid y descent with functional TR (tricuspid regurgitation).

-Inspection & palpation
Apical impulse may be shifted indicating right ventricle hypertrophy & dilation.
visible & palpable left parasternal heaving & epigastric pulsations indicating right ventricle hypertrophy.
Palpable P2.

Auscultatory
Pulmonary ejection sound.
Abnormal S2.
Right atrial 4th heart sound S4.
Right ventricle 3rd heart sound S3.
Pulmonary ejection systolic murmur.
Pulmonary early diastolic murmur.
Tricuspid pan-systolic murmur.

Investigations

ECG
Right axis deviation.
Right atrial enlargement.
Right ventricle hypertrophy.

2. Chest X-ray
Enlargement of pulmonary trunk & its main branches.
Peripheral pruning of vascular shadows.
Enlarged right atrium.
Enlarged right ventricle.

3. Echocardiography

4. Other
Routine autoantibodies if collagen vascular disease.
HIV ELISA.
Arterial blood gas to exclude hypoxia / acidosis.
Sleep studies.
Helical CT.
High resolution chest CT.
Cardiac catheterization.

Treatment

-Directed early recognition & treatment of underlying cause.
-Pulmonary endarterectomy is current mainstay of chronic thromboembolic pulmonary HTN.
-Treatment of hypoxemia by low flow oxygen.
-Excessive diuretics avoided.
-Drugs like ilioprost, bosentan, sildenafil.
-Oral anticoagulants can be used.