I now have a thorough view of the ECG image and the relevant textbook reference. Let me compile the full analysis.
ECG Analysis
Patient details (from strip header): Female, age partially visible (~10 years old based on the printed header reading "H: 0 cm / W: 0 kg" - likely a pediatric/adolescent patient), recorded on a Bionet ECG2000 machine at 25 mm/s, 10 mm/mV calibration.
Systematic Reading
1. Rate
The R-R intervals are short and regular. Counting beats across the rhythm strip, the rate is approximately 100-110 bpm - consistent with sinus tachycardia.
2. Rhythm
- Regular R-R intervals
- P waves are visible before every QRS, upright in lead II, inverted in aVR - this confirms normal sinus rhythm (but at the tachycardic end)
3. Axis
- QRS is predominantly positive in leads I and II
- Normal axis (approximately 0° to +60°)
4. P Wave
- Normal morphology in most leads
- No obvious broadening or bifid P waves to suggest left atrial enlargement
5. PR Interval
- Appears normal (~120-200 ms)
6. QRS Duration
- Narrow QRS complexes throughout - no bundle branch block
Key Abnormalities
PRIMARY FINDING: Left Ventricular Hypertrophy (LVH)
This is the dominant abnormality. Looking at the precordial leads:
- V1/V2: Very deep S waves
- V5/V6: Tall, prominent R waves
- Sokolow-Lyon voltage criterion: S in V1 + R in V5 (or V6) appears to exceed 35 mm - consistent with LVH by standard criteria
Additionally:
- ST-segment depression with T-wave inversion in V4-V6 (lateral leads) - this is the classic LV "strain" pattern, indicating repolarization abnormality from pressure/volume overload
- Tall R waves in aVL - further supporting LVH
SECONDARY FINDING: Sinus Tachycardia
- Rate ~100-110 bpm with regular P-before-QRS morphology
POSSIBLE FINDING: Left Atrial Abnormality
- The P waves in lead II appear slightly broad/bifid in some beats, which, per Harrison's, "increases the likelihood of underlying left ventricular hypertrophy in cases with borderline voltage criteria"
Summary Interpretation
| Finding | Detail |
|---|
| Rhythm | Sinus tachycardia (~100-110 bpm) |
| Axis | Normal |
| LVH | Tall R in V5/V6 + deep S in V1/V2 (Sokolow criteria >35 mm) |
| LV strain pattern | ST depression + T-wave inversion in lateral leads (V4-V6, I, aVL) |
| QRS | Narrow - no BBB |
Clinical Correlation
In a female patient (possibly adolescent/young adult given the age field), LVH with strain pattern on ECG raises the following differential:
- Hypertensive heart disease - most common cause of LVH with strain
- Hypertrophic cardiomyopathy (HCM) - especially in a younger patient; can show massive precordial voltages with deep T-wave inversions
- Aortic stenosis - pressure overload LVH
- Athletic heart - though strain pattern is atypical for this and should prompt further workup
Echocardiography is mandatory to confirm LVH, assess wall thickness, cavity size, and diastolic/systolic function. The ECG alone has limited sensitivity and specificity for LVH - as Harrison's notes, "more definitive anatomic and functional information is provided by echocardiographic and cardiac MRI studies."
Harrison's Principles of Internal Medicine 22E - "Multiple voltage criteria for left ventricular hypertrophy have been proposed based on the presence of tall left precordial R waves and deep right precordial S waves (e.g., SV₁ + RV₅ or RV₆ >35 mm). Repolarization abnormalities (ST depression with T-wave inversions, the left ventricular 'strain' pattern) may appear in leads with prominent R waves."