CONTENTS
- Normal R-wave transition
- Irregular R-wave transition
- PRWP (poor R-wave progression)
- Persistent S wave in V6
Normally, the QRS complex should smoothly transition from negative to positive (moving from V1-V6). The point where the QRS goes from predominantly negative to predominantly positive is generally between V3 and V4. If the transition occurs beyond V4, that's regarded as a late R-wave transition (with a differential diagnosis as explored below).
Early R-wave transition refers to patients with a predominantly positive QRS complex in V1 (R>S). The differential diagnosis of that finding is located here. 📖
definition
- Normally, R-waves should gradually increase in size from V1-V6.
- Irregular R-wave transition refers to R-waves that increase in size, decrease, and then increase in size again (moving from V1 to V6).
differential diagnosis
#1/3) Lead misplacement
- Very abrupt transitions in morphology may suggest this.
- Example below.
#2/3) Posterior Q-wave MI
- A posterior MI will generate Q-waves that manifest as positive R-waves in the right precordium (essentially the mirror image of a Q-wave in the opposing myocardial wall).
- Tall R-waves in the right precordium that subsequently recede as one progresses towards the left precordium may reveal a Q-wave posterior MI (either remote or subacute).
#3/3) Anterior Q-wave MI
- Anterior Q-wave MI may cause focal loss of R-waves. This loss of R-waves is fundamentally similar to a Q-wave (one may imagine that a Q-wave cancels out the R-wave without being able to manifest as an isolated entity on the ECG).
definition of PRWP
- The best definition might be V4 with S ≧ R (i.e., R-wave transition occurs after V4).
- PRWP is also sometimes defined as an R-wave amplitude in V3 ≦3 mm. (Berberian 2021) However, taken alone, this captures a lot of patients who have low voltage (rather than misalignment of the electrical axis of the heart).
- PRWP is not highly specific for any specific disorder, but it bears consideration for several possible abnormalities. Sometimes, PRWP may relate to incorrect electrode placement (too high up), so a slightly abnormal R-wave transition shouldn't necessarily raise an alarm.
- There are some additional etiologies of PRWP that aren't listed below because they should be diagnosed by other aspects of the ECG (e.g., LBBB, dextrocardia).
considerations in PRWP
- High electrode placement. ⚡️
- RVH.⚡️
- Lung hyperinflation pattern.⚡️
- LAHB.⚡️
- LVH (including DCM).⚡️
- Prior anterior MI. ⚡️
[1/6] High electrode placement 📖
- Other findings may include:
- [1] V1 has an entirely negative P-wave (this may occur with LAA, but in LAA, it would often be accompanied by a broad P-wave in lead II).
- [2] V2 has a negative or biphasic P-wave (it should be purely positive).
- [3] QRS in aVR looks similar to V1 (and sometimes V2).
- [4] Morphologic abnormalities may include:
- RSR' in V1 and/or V2:
- If seen, an Rsr' pattern supports that this is a false incomplete RBBB (generally, the right bunny ear should be taller).
- There should be an absence of prominent/blunted S-waves in leads I and V6 (arguing against a global alteration in right ventricular depolarization).
- STE, often in a saddleback configuration. (22938933)
- TWI in V2 (TWI may be normal in V1, but generally not in V2). However, persistent juvenile TWI may TWI in V2. 📖
- RSR' in V1 and/or V2:
[2/6] RVH
- ECG diagnosis of RVH is discussed further here: 📖
- PRWP may also rarely occur with isolated LPFB, so LPFB could be a consideration in this situation. (Zema 2009)
[3/6] lung hyperinflation pattern 📖
- 🔑 Prominent P-waves in inferior leads.
- 🔑 Lead-I sign (low voltage in lead I).
- 🔑 Low voltage (sometimes with shrinkage of QRS voltage in V4->V5->V6).
- 🔑 Slow R-wave progression in V1-V3.
- 🔑 S-waves in V6 and Lead I.
- ⚠️ No unexplained features suggest PE/RVH 📖 (e.g., right precordial TWI, RBBB, tall R-V1).
[4/6] LAHB
- [1] QRS <120 ms (often ~100-120 ms).
- [2] Left axis deviation with an axis between -45 to -90 degrees. (19228822)
- [3] rS in III and aVF (III may be sufficient).
- Usually, S-III > S-II. Alternatively, if S-II > S-III, this may suggest right ventricular enlargement. (de Luna 2022)
- [4] qR in aVL and I.
- [5] At least one of the following indicators of poor conduction:
- aVL has R peak time >45ms and/or slurred R downstroke.
- Slurred S in V5/V6.
[5/6] LVH (including DCM)
- This may include dilated cardiomyopathy. 📖 Note Goldberger's triad for DCM:
- [1] Low voltage in the limb leads (<8 mV).
- [2] LVH that is driven by large precordial voltages (e.g., modified Sokolow-Lyon criteria).
- [3] Delayed R-wave progression (with S>R in V4). Slow R-wave progression may be followed by an abrupt transition from a deep S-wave to a tall R-wave.
- Discussed further here: 📖
[6/6] prior anterior MI
- This may be suggested by:
- [a] Frank Q-waves (e.g., in V2-V3).
- [b] Loss of R-wave progression (i.e., irregular R-wave progression; discussed above).
- [c] Loss of R-wave amplitude in lead I (e.g., <~4 mm). (15895699)
- [d] Fragmentation, or slurring of the initial downslope of the QRS complex.
- [e] Signs of prior MI elsewhere in the ECG (e.g., inferior Q-waves).
Sometimes R-wave progression is initially normal (e.g., with R>S in V4), but subsequently stalls out. This leads to a persistent S-wave in V6 (a lead where the S-wave is usually absent). Causes include:
- RBBB (right bundle branch block).
- PE or RVH (right ventricular hypertrophy).
- Lung hyperinflation pattern.
- LPFB (left posterior hemiblock).
- LAHB (left anterior hemiblock).
- Prior MI (especially lateral wall MI).
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References
- 15895699 MacKenzie R. Poor R-wave progression. J Insur Med. 2005;37(1):58-62 [PubMed]
