Makindo Medical Notes.com

Related Subjects: |Pulmonary Stenosis |Pulmonary Regurgitation |Pulmonary Hypertension |Pulmonary Embolism

Shunts will always try to shift blood to the low-pressure pulmonary circulation but this will cause pulmonary hypertension. Pulmonary hypertension may be primary or secondary depending on whether a secondary cause can be found and is based on the mean pulmonary artery pressure readings mean > 25 mmHg at rest and 30 mmHg at exercise

About

• Pulmonary hypertension/cor pulmonale is defined as fluid overload due to lung disease in hypoxic patients with COPD
• Cor pulmonale is really secondary pulmonary hypertension due to hypoxic vasoconstriction of pulmonary vessels and Parenchymal and vascular changes - Emphysema most commonly
• There is chronic elevation of pulmonary artery pressure above 25 mmHg at rest or > 30 mmHg with exercise although the WHO definition raises the systolic pulmonary artery pressure to 40 mmHg

Classification

• Pulmonary arterial hypertension
• Pulmonary venous hypertension
• PH associated with respiratory disease/hypoxia
• PH related to thrombosis or embolic disease
• PH due to disease of the pulmonary vasculature

Pathophysiology of Pulmonary Hypertension

• Increase in LV filling pressure with a normal PVR e.g. Mitral Stenosis
• Pulmonary vascular disease with an elevated PVR e.g. pulmonary emboli
• Parenchymal lung disease with an elevated PVR e.g. DPLD
• A Combination of all of the above

Causes

• Chronic Obstructive Pulmonary disease
• Interstitial lung disease
• Idiopathic -Primary Pulmonary Hypertension
• Multiple Pulmonary emboli
• Congenital heart disease with Eisenmenger's
• Mitral stenosis
• Weakness of respiratory muscles
• Chest wall deformities
• Sickle cell disease
• Dexfenfluramine
• Left Ventricular Failure
• Left atrial myxoma
• Living at a High altitude

Clinical

• Breathlessness on exertion due to COPD
• Raised JVP, Tricuspid regurgitation, Loud P2, Parasternal heave
• Fluid retention, ankle swelling

Investigations

• FBC: polycythaemia, WCC
• U&E, LFTs, Bone profile, CRP
• ECG - RVH and RBBB and P pulmonale, RV strain pattern
• Arterial blood gas: hypoxia, hypercarbia
• CXR - enlarged PA + pruning of peripheral vessels
• Echo - RV dilatation and TR. Pulmonary hypertension is based on the mean pulmonary artery pressure readings mean > 25 mmHg at rest and 30 mmHg at exercise
• CT-PA - may suggest a diagnosis of recurrent PE as a cause

Management

• Long term oxygen therapy to reduce hypoxaemia and pulmonary vasoconstriction is indicated as well as to improve morbidity and decrease mortality. In COPD, a PaO₂ of = 7.3 kPa is an indication for home oxygen treatment. LTOT has been shown to reduce mortality, pulmonary resistance and hypoxia, and might produce symptomatic relief.
• Anticoagulation: if due to recurrent small pulmonary emboli - have a low threshold for looking for PE with CT-PA or Ventilation-Perfusion scanning. May also be needed for AF.
• Diuretics are used for fluid retention but care so as not to reduce the volume that impairs RV filling
• ACE inhibitors have little effect and may worsen the situation and there is no evidence either for low dose Beta-Blockers