ECG changes occur in COPD due to:
- The presence of hyperexpanded emphysematous lungs within the chest.
- The long-term effects of hypoxic pulmonary vasoconstriction upon the right side of the heart, causing pulmonary hypertension and subsequent right atrial and right ventricular hypertrophy (i.e. cor pulmonale).
Effects of Emphysema on the Heart
- Lung hyperexpansion causes external compression of the heart and lowering of the diaphragms, with consequent elongation and vertical orientation of the heart.
- Due to its fixed attachments to the great vessels, the heart undergoes clockwise rotation in the transverse plane, with movement of the right ventricle anteriorly and displacement of the left ventricle posteriorly.
- The presence of increased air between the heart and recording electrodes has a dampening effect, leading to reduced amplitude of the QRS complexes.
Lung hyperexpansion and vertical orientation of the heart
Effects on the pulmonary vasculature
- Chronic hypoxaemia causes reflex vasoconstriction in the pulmonary arterioles (“hypoxic pulmonary vasoconstriction”), with consequent elevation of pulmonary arterial pressures.
- Destruction of lung tissue with loss of pulmonary capillaries increases the resistance of the pulmonary vascular bed by reducing its effective surface area.
- Over time, this chronic elevation of pulmonary arterial pressures results in compensatory right atrial and right ventricular hypertrophy.
The most typical ECG findings in emphysema are:
- Rightward shift of the P wave axis with prominent P waves in the inferior leads and flattened or inverted P waves in leads I and aVL.
- Rightward shift of the QRS axis towards +90 degrees (vertical axis) or beyond (right axis deviation).
- Exaggerated atrial depolarisation causing PR and ST segments that “sag” below the TP baseline.
- Low voltage QRS complexes, especially in the left precordial leads (V4-6).
- Clockwise rotation of the heart with delayed R/S transition point in the precordial leads +/- persistent S wave in V6. There may be complete absence of R waves in leads V1-3 (the “SV1-SV2-SV3″ pattern).
With development of cor pulmonale, the following additional changes are seen:
Other ECG changes that may be seen include:
- Right bundle branch block (usually due to RVH)
- Multifocal atrial tachycardia – a rapid, irregular atrial tachycardia with at least 3 distinct P wave morphologies (associated with increased mortality in patients with COPD).
Sagging of the PR and ST segments below the TP baseline
Clockwise rotation of the heart
Multifocal Atrial Tachycardia
This ECG demonstrates many of the features of chronic pulmonary disease:
- Rightward QRS axis (+90 degrees).
- Peaked P waves in the inferior leads > 2.5 mm (P pulmonale) with a rightward P-wave axis (inverted in aVL)
- Clockwise rotation of the heart with a delayed R/S transition point (transitional lead = V5).
- Absent R waves in the right precordial leads (SV1-SV2-SV3 pattern).
- Low voltages in the left-sided leads (I, aVL, V5-6).
Sinus tachycardia may be due to breathlessness, hypoxia or bronchodilator therapy (e.g. salbutamol, theophylline).
Another good example of the pulmonary disease pattern:
- Rightward axis (+ 90 degrees).
- Peaked P waves.
- Low QRS voltages (most obvious in the limb leads).
- Clockwise rotation (transitional lead = V6).
- Virtually absent R waves in the right precordial leads (SV1-SV2-SV3 pattern).
This ECG shows multifocal atrial tachycardia with additional features of COPD:
- Rapid, irregular rhythm with multiple P-wave morphologies (best seen in the rhythm strip).
- Right axis deviation, dominant R wave in V1 and deep S wave in V6 suggest right ventricular hypertrophy due to cor pulmonale.
For more great ECG examples of the abnormalities seen with pulmonary disease, check out these related pages from the ECG library.
- ECG BASICS — Waves, Intervals, Segments and Clinical Interpretation
- ECG CLINICAL CASES — Your favourite ECG’s placed in clinical context with a challenging Q&A approach
- ECG and Cardiology Eponymous Syndromes — Cheats guide to eponymous emancipation
- ECG Exam Template — a framework for the FACEM part 2 exam.
- ECG Reference Sites on the WEB — the best of the rest
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- Harrigan RA, Jones K. ABC of clinical electrocardiography. Conditions affecting the right side of the heart. BMJ. 2002 May 18;324(7347):1201-4. Review. PMID: 12016190. Full text.
- Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice (6th edition), Saunders 2008.
- Wagner, GS. Marriott’s Practical Electrocardiography (11th edition), Lippincott Williams & Wilkins 2007.