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    3.2
    Home > ECG findings

    3.2

    Minnesota Code 3-2: dominant R wave in V1 (R ≥ 5 mm, R/S ≥ 1) suggesting right ventricular hypertrophy; other causes to exclude.

    Code 3.2 — Minnesota Code 3-2: high-amplitude R wave in V1 (right). This code is assigned when the R wave in lead V1 is 5 mm or more and dominant over the S wave (R/S ≥ 1). Normally V1 shows a small r and a deep S, because the thick left ventricle dominates. A tall R in V1 suggests that the right ventricle has become thicker — right ventricular hypertrophy (RVH) — or that the electrical forces are redirected for another reason.

    Minnesota Code 3Tall R in V1Right ventricular hypertrophy
    CriterionR ≥ 5 mm and R/S ≥ 1 in V1
    Suggestsright ventricular hypertrophy
    Often withright axis deviation
    ExcludeRBBB, posterior MI, WPW
    Normal small r and deep S wave in lead V1 compared with a dominant tall R wave in V1 suggesting right ventricular hypertrophy Normal V1 rS pattern Code 3-2 R ≥ 5 mm, R/S ≥ 1
    Figure 1. Left: normal V1 with small r and deep S. Right: dominant R wave in V1 (R ≥ 5 mm, R/S ≥ 1, Minnesota 3-2), often with secondary ST-T changes in right ventricular hypertrophy.

    Causes of a tall R wave in V1

    CauseClues
    Right ventricular hypertrophyRight axis deviation, P pulmonale, ST-T "strain" in V1–V3; pulmonary hypertension, COPD, pulmonary stenosis, congenital heart disease, chronic pulmonary embolism
    Right bundle branch blockQRS ≥ 120 ms with rSR′ pattern (see code 3.21 / 7.21)
    Posterior (inferobasal) myocardial infarctionTall, wide R in V1–V2 with upright T, often with inferior Q waves
    WPW pattern (left-sided accessory pathway)Short PR and delta wave
    OtherHypertrophic cardiomyopathy, muscular dystrophy, dextrocardia, lead misplacement; normal variant in children and young adults

    Clinical significance

    The ECG detects right ventricular hypertrophy with low sensitivity but reasonable specificity. When present, RVH usually reflects increased pressure in the pulmonary circulation, which can lead to right-sided heart failure (leg swelling, liver enlargement, fatigue). Echocardiography assesses right ventricular size and estimates pulmonary artery pressure.

    When to see a doctor

    Arrange an evaluation if this finding is new, particularly with breathlessness on exertion, chronic lung disease, leg swelling, fainting on exertion or a history of blood clots in the lungs.

    References

    1. 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
    2. 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

    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