3.41
Code 3.41 — Minnesota Code 3-4: combined high R waves (left and right). This code is assigned when the criteria of code 3-1 (high R in the left leads) and code 3-2 (dominant R in V1) are present at the same time. The pattern suggests enlargement of both ventricles (biventricular hypertrophy), with a marked contribution of the right ventricle — an abnormal thickening of the right ventricular wall caused by increased pressure in the lungs or a heart defect.
Why both ventricles show high voltage
Normally the left ventricle is much thicker than the right and dominates the ECG, so the right ventricle is "hidden". When the right ventricle becomes thick enough, its forces shift the QRS towards the right and produce a dominant R wave in V1, while the enlarged left ventricle still produces tall R waves in V5–V6. Because the forces partly cancel each other, the ECG detects biventricular hypertrophy with low sensitivity.
Causes
| Group | Examples |
|---|---|
| Congenital heart defects | Ventricular septal defect, patent ductus arteriosus, tetralogy of Fallot after repair |
| Left heart disease with pulmonary hypertension | Mitral stenosis or regurgitation, long-standing left ventricular failure |
| Lung and pulmonary vascular disease plus hypertension | COPD, sleep apnoea, chronic thromboembolic pulmonary hypertension |
| Cardiomyopathies | Hypertrophic or infiltrative cardiomyopathy involving both ventricles |
Clinical significance
Involvement of the right ventricle usually means that pressure in the pulmonary circulation is raised. Untreated, this may lead to right heart failure, with leg swelling, an enlarged liver, fatigue and breathlessness on exertion. Echocardiography measures the thickness of both ventricles and estimates pulmonary artery pressure; additional tests depend on the suspected cause.
A cardiology assessment is needed for this finding, especially with breathlessness, leg swelling, a heart murmur, cyanosis (bluish lips) or fainting during exertion.
References
- Prineas RJ, Crow RS, Zhang ZM. The Minnesota Code Manual of Electrocardiographic Findings. 2nd ed. London: Springer; 2010. doi:10.1007/978-1-84882-778-3
- Hancock EW, Deal BJ, Mirvis DM, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part V: electrocardiogram changes associated with cardiac chamber hypertrophy. Circulation. 2009;119(10):e251–e261. doi:10.1161/CIRCULATIONAHA.108.191097
This article is for general information and does not replace a consultation with a doctor. ECG findings must be interpreted by a physician together with symptoms and other tests.
Published on 14 May 2019