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 25mm of Hg / a resting systolic pulmonary artery pressure greater than 40mm Hg.


Etiology and classification:



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 venous HTN



  • Left sided atrial / ventricular heart disease.
  • Left sided valvular heart disease.


Pulmonary HTN associated with hypoxemia



  • COPD.
  • Interstitial lung disease.
  • Obstructive sleep apnoea.


Pulmonary HTN due to chronic thrombotic / embolic disease



  • Thromboembolism to proximal pulm arteries.
  • Obstruction of distal pulmonary arteries in pulmonary embolism, sickle cell disease.


Miscellaneous



  • Sarcoidosis, histiocytosis X


Pathophysiology:



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


Clinical features



1)Symptoms of pulmonary HTN & its consequences



  • 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 :- Prominent ‘a’ waves, JVP elevated with right ventricle failure, prominent ‘v’ waves & rapid ‘y’ descent with functional TR.



Inspection & palpation



  • Apical impulse may be shifted indicating right ventricle hypertrophy & dilatation.
  • Visible & palpable left parasternal heaving & epigastric pulsations indicating right ventricle hypertrophy.
  • Palpable p2.




Auscultation



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


Investigation:



1)ECG





  • Shows Right axis deviation.
  • Right atrial enlargement.
  • With 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:



Endarterectomy


  • Directed at 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 Iloprost, Bosentan, Sildenafil.
  • Oral anticoagulants can be given.