What is the role of electrocardiography in the diagnosis of cor pulmonale?

Updated: Dec 15, 2017
  • Author: Derek Leong, MD; Chief Editor: Henry H Ooi, MD, MRCPI  more...
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Electrocardiographic (ECG) abnormalities in cor pulmonale reflect the presence of right ventricular hypertrophy (RVH), RV strain, or underlying pulmonary disease (see the image below). Such ECG changes may include the following:

  • Right axis deviation

  • R/S amplitude ratio in V1 greater than 1 (an increase in anteriorly directed forces may be a sign of posterior infarction)

  • R/S amplitude ratio in V6 less than 1

  • P-pulmonale pattern (an increase in P wave amplitude in leads 2, 3, and aVF)

  • S1 Q3 T3 pattern and incomplete (or complete) right bundle branch block, especially if pulmonary embolism is the underlying etiology

  • Low-voltage QRS because of underlying COPD with hyperinflation

Severe RVH may reflect as Q waves in the precordial leads that may be mistakenly interpreted as an anterior myocardial infarction (however, as electrical activity of the RV is significantly less than the left ventricle [LV], small changes in RV forces may be lost in the ECG). See the image below.

This ECG shows some typical abnormalities that may This ECG shows some typical abnormalities that may be seen in cor pulmonale and other chronic pulmonary diseases: (1) R/S ratio >1 in V1 and <1 in V6 suggestive of right ventricular hypertrophy/enlargement, (2) right superior axis deviation, (3) left atrial type of p wave with increased width of the p wave and biphasic p wave in V1, and (4) right bundle branch block pattern with wide QRS and RsR1 pattern in V1 and slurred s wave in V6.This ECG also presents a sinus bradycardia rhythm with first-degree AV block and left anterior fascicular block.

Additionally, many rhythm disturbances may be present in chronic cor pulmonale; these range from isolated premature atrial depolarizations to various supraventricular tachycardias, including paroxysmal atrial tachycardia, multifocal atrial tachycardia, atrial fibrillation, atrial flutter, and junctional tachycardia. These dysrhythmias may be triggered by processes secondary to the underlying disease, (eg, anxiety, hypoxemia, acid-base imbalance, electrolyte disturbances, excessive use of bronchodilators, heightened sympathetic activity). Life-threatening ventricular tachyarrhythmias are less common.

In selected cases, pulmonary function testing may be indicated to determine underlying obstructive or interstitial lung disease.

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