Electrocardiography (ECG) in Pulmonary Disorders

Electrocardiography (ECG) is a useful adjunct to other pulmonary tests because it provides information about the right side of the heart and therefore pulmonary disorders such as chronic pulmonary hypertension and pulmonary embolism.

(See also Electrocardiography in cardiovascular disorders.)

Chronic pulmonary hypertension leading to chronic right atrial dilation and right ventricular hypertrophy and dilation may manifest as P waves of higher amplitude (P pulmonale) and ST-segment depression in leads II, III, and aVF; rightward shift in QRS axis; inferior shift of the P wave vector; and decreased progression of R waves in precordial leads.

Patients with chronic obstructive pulmonary disease (COPD) commonly have low voltage due to interposition of hyperexpanded lungs between the heart and ECG electrodes (1).

Pulmonary embolism (submassive or massive) may cause acute right ventricle overload or failure, which manifests classically (but not commonly) as right axis deviation (QRS axis between 90 and 180 degrees with R > S in V1, occurring in 28% of patients with pulmonary embolism), with S-wave deepening in lead I, Q-wave deepening in lead III, and ST-segment elevation and T-wave inversion in lead III and the precordial leads (S1Q3T3 pattern, occurring in approximately 15% of patients with pulmonary embolism) (2). Right bundle branch block and T-wave inversion in leads V1 to V3 also sometimes occur. Sinus tachycardia is the most common ECG finding in pulmonary embolism and occurs in approximately 30% of patients with pulmonary embolism.