Acute cor pulmonale

Acute cor pulmonale (pulmonary embolus – PE):

A thrombus formed in the systemic veins may dislodge and embolize into the pulmonary arterial system.

• After PE, lung tissue is ventilated but not perfused, leading to impaired gaseous exchange
• After some hours, surfactant is no longer produced by the non-perfused lung
• Alveolar collapse occurs and exacerbates hypoxaemia
• The haemodynamic consequence of PE is an elevation of pulmonary arterial pressure and a reduction in cardiac output

Clinical features of PE:

Many Pulmonary emboli occur silently, but there are 3 typical clinical presentations:

Small/medium PE:

• In this situation, an embolus has impacted in a terminal pulmonary vessel
• Symptoms are:
• Pleuritic chest pain
• Breathlessness
• Haemoptysis (in ~30%, occurring >3 days after the initial event)

• On examination:
• Tachypnoea
• Localized pleural rub
• Coarse crackles over the involved area
• A pleural effusion can develop
• There may be a fever
• Normal CVS

Massive PE:

• Much rarer scenario
• Sudden collapse occurs due to an acute obstruction of the right ventricular outflow tract
• Symptoms:
• Severe central chest pain (cardiac ischaemia due to lack of coronary blood flow)
• Shock
• Death can occur

• On examination:
• Tachypnoea
• Tachycardia
• Hypotension
• Peripheral vasoconstriction
• Raised JVP
• Right ventricular heave
• Gallop rhythm
• Widely split second heart sound

Multiple recurrent pulmonary emboli:

• Symptoms:
• Increasing breathlessness (often over weeks or months)
• Weakness
• Syncope on exertion
• Angina (occasionally)
• On examination:
• Signs of right ventricular overload
• Right ventricular heave
• Loud pulmonary second heart sound

Diagnosis of PE:

PE should be considered if patients present with symptoms of new-onset AF (or other tachycardia), unexplained breathlessness or cough, if no other obvious cause is present.

Investigations for PE:

CXR:

• Usually normal in small/medium PE
• May show pulmonary oligaemia with a massive PE

ECG:

• In small/medium PE, there is usually sinus tachycardia or AF
• In massive PE there is:
• Tall peaked T waves in lead II
• Right axis deviation
• Right bundle branch block

Blood tests:

• Hypoxia and hypercapnia
• Raised ESR/LDH due to pulmonary infarction

Plasma D-dimer:

• If undetectable, it excludes the diagnosis of PE

Radionucleotide ventilation-perfusion scan (V/Q scan):

Ultrasound:

• To detect clots in pelvic/lower limb veins

Spiral CT scans

MRI

Acute management:

High-flow O₂, unless they have significant chronic lung disease

In severe cases:

• IV fluids
• Inotropic agents

Analgesia

Dissolution of the thrombus:

• Streptokinase 250,000U IVI over 30 minutes, followed by streptokinase 100,000U IV hourly is often used following a major embolism

Prevent further emboli:

• The basis of therapy is IV heparin
• Give a bolus of 10,000U of unfractionated heparin followed by a continuous infusion of 1000-2000U per hour
• Oral anticoagulants are usually begun after 48 hours and the heparin is tapered off as the oral anticoagulant becomes effective
• Oral anticoagulants are continued for 6 weeks to 6 months