Pulmonary Hypertension

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Pulmonary Hypertension

Definition: a consistently increased pulmonary arterial pressure (> 20mmHg) under resting conditions, which can lead to cor pulmonale- right ventricular failure secondary to pulmonary hypertension.

Aetiology/risk factors:

Occurs due to an increase in pulmonary vascular resistance or an increase in pulmonary blood flow.

Causes:

Primary pulmonary hypertension: idiopathic

Secondary:

Left heart disease– mitral valve disease, left ventricular failure, left atrial myxoma/thrombosis

Chronic lung disease– COPD, bronchiectasis, pulmonary fibrosis, severe chronic asthma, lung resection

Pulmonary vascular disorders– pulmonary emboli, pulmonary vasculitis,  ARDS, sickle-cell disease, parasite infestation

Increased pulmonary blood flow– atrial septal defect, ventral septal defect, patent ductus arteriosus

Neuromuscular disease– myasthenia gravis, poliomyelitis, motor neuron disease

Skeletal disease– kyphosis, scoliosis, thoracoplasty (rib resection)

Connective tissue disease– SLE, systemic sclerosis

Hypoventilation– sleep apnoea, enlarged adenoids in children

Drugs-amiodarone

Epidemiology: primary pulmonary hypertension is usually seen in young females

Symptoms:

-dyspnoea (on exertion), fatigue, lethargy = inability to increase cardiac output with exercise

-syncope

-chest pain

-symptoms of underlying cause e.g. chronic cough

As right ventricular failure develops:

-peripheral oedema

-abdominal pain from hepatic congestion

Signs:

-cyanosis

-tachycardia

-raised JVP (with prominent a and v waves)

-right ventricular/left parasternal heave (hypertrophy)

loud P2

pansystolic murmur (tricuspid regurgitation)

early diastolic Graham Steell murmur (pulmonary regurgitation secondary to pulmonary hypertension)

Signs of underlying condition e.g. hyper-resonant chest in COPD

Signs of right heart failure if severe:

-hepatomegaly, pulsatile liver

-oedema, ascites

-pleural effusion

Investigations:

FBC- raised Hb and haematocrit (secondary polycythaemia in chronic lung disease)

ABG- hypoxia +/- hypercapnia

CXR- enlarged right atrium and ventricle, prominent pulmonary arteries

            signs of cause e.g. COPD, calcified mitral valve

Image result for cor pulmonale cxr

CXR in primary pulmonary hypertension showing right heart enlargement and enlargement of the main pulmonary artery and its right and left branches

ECG-

  • P pulmonale (peaked P wave = right atrial hypertrophy, usually in lead II)
  • Right axis deviation
  • Right ventricular hypertrophy/ strain (RVH- dominant R wave in V1 + deep S wave in V6, T wave inversion in V1-V3 or V4. RV strain- dominant R wave + T wave inversion/ST depression in V1-2. Leads II, III, aVF may show similar changes.)
  • Limb leads exhibit low voltage in COPD

Image result for cor pulmonale ecg

Echo- to visualise right ventricular hypertrophy or dilation and possible underlying case e.g. mitral disease

Lung function tests- to assess for chronic lung disease

Cardiac catheterisation– to assess severity, right heart pressures and response to vasodilators

High-resolution CT thorax- images pulmonary arteries and to diagnose lung disease

Lung biopsy- assesses structural lung changes

Management:

-treat underlying cause e.g. COPD and pulmonary infections

-for primary pulmonary hypertension consider:

  • anticoagulation (warfarin)- due to high risk of thrombosis
  • calcium channel blockers (e.g. verapamil, nifedipine)
  • prostacyclin analogues (e.g. iloprost) Epoprostenol = IV prostacyclin .
  • endothelin receptor antagonist (bosentan) blocks vasoconstriction but teratogenic so only considered in later stage
  • phosphodiester inhibitors (e.g. sildenafil) promote pulmonary smooth muscle relaxation reducing pulmonary hypertension

treat respiratory failure

= acutely, 24% oxygen if PaO2 < 8kPa.

= monitor ABG and gradually increase O2 concentration if PaCO2 is stable.

=long-term oxygen therapy for 15h/d in COPD patients increases survival

NICE guidelines suggest LTOT for COPD patients with PaO2 < 7.3 kPa or < 8kPa if they have pulmonary hypertension.

treat cardiac failure

=diuretics e.g. furosemide, spironolactone

=monitor U&Es and give amiloride (potassium-sparing diuretic) or potassium supplements if necessary.

-consider venesection if haematocrit > 55% (percentage of blood volume that is red blood cells)

-consider heart-lung transplantation in young patients

Complications: respiratory failure, right heart failure (cor pulmonale), arrhythmias (AF/VT/VF), sudden death

Prognosis: poor. Chronic and incurable with unpredictable survival rate. Length of survival has improves to up to 15-20 years.

50% with cor pulmonale die within 5 years.

References: Cheese & Onion, Rapid Medicine

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