Introduction
The early phase of pivotal testing for pulmonary hypertension should include an electrocardiogram (ECG) as part of the work-up. An abnormal ECG waveform may indicate that the heart, or part of the heart, is under stress.
Usefulness of the ECG
ECG, usually a 12-lead, may give evidence of right ventricular hypertrophy or right atrial enlargement in pulmonary hypertension. As pulmonary arterial pressure increases, the ECG becomes more sensitive. However, ECG alone cannot be used to measure or infer pulmonary artery pressure, right atrial pressure, right ventricular end diastolic pressure, or any other pulmonary blood pressure parameter. It is important that the ECG be interpreted by a health care provider specifically trained to analyze the complex wave forms from the various leads of the recording in order to obtain an accurate ECG interpretation.
Any patient with complaints of dyspnea upon exertion and suggestive history, physical exam, chest X-ray and ECG should be referred for Doppler ECHO. When looking at an ECG, the following abnormalities are useful in raising the suspicion of PAH: right axis deviation, increased P-wave amplitude in lead II, and
incomplete right bundle branch block.
Image courtesy of Dr. Paul Forfia
Figure 1 shows an ECG demonstrating important abnormalities that are positive signs of pulmonary hypertension. Important abnormalities in the ECG are highlighted within the image. Of particular note are the waveforms indicating right ventricular hypertrophy and right ventricular strain, which are critical indicators of a heart under stress with an increased afterload in the right ventricle. Right ventricular hypertrophy and strain indicate severe dysfunction in the RV, which may reduce right heart ejection fraction in the face of elevated pulmonary arterial pressures.
References
1. Widimsky J. Non-invasive diagnosis of pulmonary hypertension in chronic lung diseases. Prog Respir Res 1985;20:69-75.
2. McLaughlin VV, Archer SL, Badesch DB, et al. ACCF/AHA 2009 Expert Consensus Document on Pulmonary Hypertension, JACC, 2009; 53(17):1573-1619.
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