ECG criteria
- Measured in leads with a measurable positive R or R' wave: V1–V2 to assess the right anterior precordial leads, V5–V6 for the left lateral precordial leads
- From the beginning of the QRS complex to the peak of the R wave; if a terminal R' is present (e.g., rsR'), to the peak of the terminal R'; for a notched or monophasic R, use the corresponding final peak of the R complex
- Norm in V1–V2: ≤ 0.035 s (≤ 0.875 mm at a paper speed of 25 mm/s)
- Norm in V5–V6: ≤ 0.045 s (≤ 1.125 mm at a paper speed of 25 mm/s)
- Prolongation in V5 or V6 > 0.05 s is an auxiliary point in the Romhilt–Estes scoring system for LVH, but not an independent diagnosis
- In complete RBBB, the delay of the R' peak in V1 is typically > 0.05 s combined with QRS ≥ 0.12 s and typical rsR'/rSR' morphology
- In complete LBBB, the delay of the R peak in V5–V6 is typically ≥ 0.06 s combined with QRS ≥ 0.12 s and characteristic morphology
- Measurement is impossible if there is no measurable R or R' wave in the selected lead (e.g., a QS complex)
What it looks like on ECG
The R-wave peak time is the horizontal interval from the onset of the QRS complex to the peak of the R wave. It is measured in millimeters on paper and converted to time: at a standard speed of 25 mm/s, one millimeter corresponds to 0.04 s.
The time for right ventricular activation is usually assessed in V1–V2 when a measurable R or R' wave is present. Normally, an rS-type complex is more commonly recorded in V1, but its shape depends heavily on heart position, the transition zone, and individual anatomy; V1 is not a lead reflecting exclusively the right ventricle. The time from the onset of QRS to the peak of the r wave in V1–V2 generally does not exceed 0.035 s. For the left ventricle, V5 or V6 are used, where a tall R wave normally dominates; the time to its peak is about 0.045 s or less.
| Lead | Evaluates | Norm (s) | Norm (mm at 25 mm/s) |
|---|---|---|---|
| V1–V2 | Right anterior precordial | ≤ 0,035 | ≤ 0,875 |
| V5–V6 | Left lateral precordial | ≤ 0,045 | ≤ 1,125 |
In bundle branch block, the R wave in the corresponding leads becomes broad and frequently notched, and the time to its peak increases; this is primarily characteristic of intraventricular conduction disturbances. In hypertrophy, the R-wave peak time may be merely an additional non-specific sign of prolongation, without obligatory widening or notching of R. In complete left bundle branch block, wide notched R complexes with an R-wave peak time ≥ 0.06 s are visible in V5–V6; in right bundle branch block, a similar pattern is seen in V1 with rSR' or rsR'-type complexes.
Mechanism
The R-wave peak time is the time from the onset of QRS to the maximum positive deflection (R peak) in a given lead, roughly correlating with the moment the depolarization wave reaches the myocardium directly beneath the electrode. The sequence and polarity of waves in each lead depend on the direction of the net depolarization vector rather than a single universal "away, then toward" scheme: for instance, in V1, initial septal activation usually forms a small positive r wave, while the subsequent ventricular wall vector forms the S wave.
The R-wave peak time depends on the sequence of excitation propagation and the orientation of the electrical vector. In hypertrophy, its increase is merely an additional indirect sign. In bundle branch block, excitation propagates via bypass pathways through the myocardium rather than the His–Purkinje system, which slows conduction and increases the time to the R peak. In a normal heart, rapid synchronous excitation via Purkinje fibers ensures a short R-wave peak time.
When prolonged
Ventricular hypertrophy:
- Left ventricular hypertrophy (LVH): R-wave peak time in V5 or V6 > 0.05 s is one point in the Romhilt–Estes system; the diagnosis of LVH requires a point score and other criteria
- Right ventricular hypertrophy (RVH): increased time to the R peak in V1 is an auxiliary non-specific sign; RVH cannot be diagnosed based on this alone, voltage, axis, and morphological criteria are required
Bundle branch blocks:
- Complete left bundle branch block: time in V5–V6 is usually ≥ 0.06 s combined with QRS ≥ 0.12 s and typical morphology (broad notched R in I, aVL, V5–V6 without q waves)
- Complete right bundle branch block: delay of terminal R' in V1 is typically > 0.05 s combined with QRS ≥ 0.12 s, rsR'/rSR' in V1–V2, and a wide terminal S in I and V6
- Incomplete bundle branch blocks (QRS 110–119 ms with typical morphology): intermediate prolongation
Other causes:
- Nonspecific intraventricular conduction block
- Pronounced myocardial fibrosis
- Infiltrative cardiomyopathies
- Prior myocardial infarction with scar changes
- Ventricular pacing
How to measure correctly
Measurement is performed from the very onset of the QRS complex (the first deflection from the isoelectric line in any lead) to the peak of the R wave; if a terminal R' is present (e.g., rsR' in right bundle branch block), to the peak of the terminal R'. For a monophasic R wave, measure to its single peak. It is important to use simultaneously recorded leads to accurately determine the onset of QRS.
For the left ventricle, analyze V5 or V6 with a well-formed R wave. The dominance of an S wave does not preclude measurement in itself: if a measurable R wave is present, the time can be estimated, though reliability may decrease; measurement is impossible only in the absence of a measurable positive R/R' wave (e.g., a QS complex). For the right ventricle, use V1 or V2 under the same conditions.
In wide complexes with a gradual upstroke, exact peak identification can be difficult — in such cases, assessing the overall QRS width is more important. For comparability, use V1–V2 and V5–V6; localization interpretation is less reliable in the transition zone.
V1 — up to 3.5; V6 — up to 4.5 (normal R-wave peak time in hundredths of a second)
1. The R-wave peak time in V6 is 0.07 s with a QRS width of 0.14 s, and a wide notched R wave in I, aVL, V5–V6 without q waves. What is the most likely diagnosis?
A QRS duration ≥ 0.12 s combined with a prolonged R-wave peak time ≥ 0.06 s and typical LBBB morphology (broad notched R in I, aVL, V5–V6 without q waves) indicates complete left bundle branch block. In isolated hypertrophy without block, QRS generally does not exceed 0.11 s.
2. In which lead is the R-wave peak time measured to assess the left ventricle?
V1–V2 are used to assess activation time in the right anterior precordial leads, while V5–V6 are used in the left lateral precordial leads, which predominantly reflect the left ventricle.
3. What value of the R-wave peak time in V1 is considered the upper limit of normal?
In lead V1, the intrinsicoid deflection time normally does not exceed 0.035 s. A value of 0.045 s is normal for V5–V6, and 0.05 s is the threshold for an additional LVH point in V5 or V6.
Frequently asked questions
How does the intrinsicoid deflection time differ from the QRS width?
The QRS width is the total duration of the ventricular complex from start to finish, including all waves. The intrinsicoid deflection time is only the segment from the onset of the QRS to the peak of the R wave in a specific lead. The former characterizes the total ventricular depolarization time, while the latter reflects the myocardial activation time beneath the electrode.
Is the intrinsicoid deflection time always measurable?
Measurement is not possible if there is no measurable R or R' in the chosen lead, such as with a QS complex. If a small but distinct R wave is present alongside a predominant S wave in V5–V6 or V1–V2, the time to its peak can be measured, although the result is less reliable.
What intrinsicoid deflection time is considered pathological?
In V5 or V6, prolongation > 0.05 s is an additional point in the Romhilt–Estes scoring system for LVH, but the diagnosis requires a point total and other criteria. In complete LBBB, the time in V5–V6 is typically ≥ 0.06 s combined with QRS ≥ 0.12 s and characteristic morphology. In complete RBBB, the delay of the terminal R' in V1 is typically > 0.05 s combined with QRS ≥ 0.12 s and typical morphology.
Should the intrinsicoid deflection time be measured on every ECG?
Not in routine practice. Most modern criteria for hypertrophy and bundle branch blocks are based on total QRS width and wave amplitudes. The intrinsicoid deflection time is measured purposefully when hypertrophy is suspected (as an additional criterion) or to clarify the nature of a block in complex cases.
Can hypertrophy be distinguished from a block based on the intrinsicoid deflection time?
The intrinsicoid deflection time value by itself is nonspecific and does not reliably distinguish between hypertrophy and block without considering QRS width and morphology. A range around 0.05 s is merely a Romhilt–Estes criterion for an additional LVH point rather than a mandatory range: hypertrophy may be accompanied by QRS ≥ 0.12 s if a conduction disturbance coexists. Diagnosing a block requires QRS ≥ 0.12 s and typical morphology (LBBB, RBBB) rather than just prolonged intrinsicoid deflection time.
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Related terms
More in the section «Basics: waves, intervals, axes»
Sources
- Surawicz B., Knilans T.K. Chou's Electrocardiography in Clinical Practice, 6th ed., 2008
- Goldberger A.L. Clinical Electrocardiography: A Simplified Approach, 9th ed., 2017
- Kligfield P. et al. Recommendations for the Standardization and Interpretation of the Electrocardiogram (AHA/ACCF/HRS), 2009
- Orlov V.N. Manual of Electrocardiography, 9th ed., 2017
Educational material for medical students and physicians. Does not replace clinical guidelines and physical examination; the ECG must always be interpreted in conjunction with the clinical picture.