From the Guidelines
R waves are positive deflections in an electrocardiogram (ECG) that represent ventricular depolarization, specifically indicating the spread of electrical activity through the main mass of the ventricular muscle, as defined in the 2019 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1. The R wave appears as an upward spike in the QRS complex, which is the most prominent feature of a normal ECG tracing. In a standard 12-lead ECG, R waves progressively increase in size from lead V1 to V5, reflecting the normal electrical axis of the heart. Some key characteristics of R waves in the context of conduction disturbances include:
- Complete Right Bundle Branch Block (RBBB): rsr', rsR, rSR, or rarely a qR pattern in leads V1 or V2, with the R' or r' deflection usually wider than the initial R wave 1
- Complete Left Bundle Branch Block (LBBB): broad notched or slurred R wave in leads I, aVL, V5, and V6, with an occasional RS pattern in V5 and V6 attributed to displaced transition of QRS complex 1 The height, width, and timing of R waves provide valuable diagnostic information about heart function. Abnormally tall R waves may indicate ventricular hypertrophy (enlarged heart muscle), while diminished R waves might suggest a myocardial infarction (heart attack) or other cardiac pathology. R wave progression across chest leads helps clinicians assess the electrical conduction system of the heart and identify potential blockages or damage to specific regions of the heart muscle. The most recent and highest quality study, the 2019 ACC/AHA/HRS guideline, provides the most accurate and up-to-date definition of R waves and their characteristics in the context of cardiac conduction disturbances 1.
From the Research
R Waves in ECG
- R waves are a component of an electrocardiogram (ECG) reading, representing the depolarization of the ventricles in the heart.
- The presence and characteristics of R waves can be affected by various conditions, including bundle branch blocks and left ventricular hypertrophy 2, 3.
- In the context of bundle branch blocks, the R wave can be altered, leading to difficulties in diagnosing conditions such as acute coronary syndromes 4.
- The differentiation between left bundle branch block and left ventricular hypertrophy is crucial, as it has implications for cardiac resynchronization therapy 4.
- Bundle branch blocks, including those affecting the R wave, can complicate acute myocardial ischemia or infarction, and are associated with a higher mortality rate 5, 6.
- The appearance of intraventricular conduction blocks and bundle branch blocks, which can affect the R wave, may be an indication of the development of high-grade atrioventricular block 5.