Explain Type C RVH on ECG

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"right ventricular hypertrophy" AND "electrocardiogram" AND "pattern"

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Type C RVH ECG pattern criteria COPD emphysema

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Type C RVH ECG pattern criteria classification

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Type A Type B Type C RVH ECG classification Chou's electrocardiography

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"type C" RVH ECG "rS pattern" "deep S" right precordial COPD cor pulmonale classification

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Type C RVH ECG pattern classification criteria COPD

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Type C RVH on ECG

The Three-Pattern Classification of RVH

RVH on ECG is traditionally classified into three types (A, B, and C) based on QRS morphology, primarily in lead V1. Understanding each helps decode the underlying pathophysiology:

Type	V1 morphology	Mechanism	Classic cause
Type A	Tall dominant R wave (R > S, or monophasic R)	Severe pressure overload dominating the LV vector	Severe pulmonary arterial hypertension, critical pulmonary stenosis
Type B	rSr' / RSr' pattern (incomplete RBBB-like)	Volume overload with mild pressure	ASD (ostium secundum), moderate mitral stenosis
Type C	Persistent rS or S1S2S3 - no tall R in V1	RV dilatation masking RVH; insulation + heart displacement	COPD/emphysema, acute cor pulmonale (PE)

Type C RVH - In Detail

Core Concept

Type C RVH is the "paradoxical" pattern: the RV is genuinely hypertrophied and/or dilated, but the classic hallmarks of RVH (tall R in V1, R/S > 1 in V1) are absent. RVH is diagnosed by proxy rather than by direct voltage criteria.

Pathophysiology - Why the Tall R Wave Is Missing

Two key mechanisms account for this in COPD/emphysema:

Diaphragmatic descent and vertical heart position - Hyperinflated lungs push the diaphragm and heart downward, rotating the QRS vector inferiorly. This makes the heart more vertical, moving electrical forces away from V1.
Pulmonary insulation effect - Hyperaerated lung tissue between the heart and precordial electrodes attenuates QRS voltages, especially in right-to-mid precordial leads. Even a hypertrophied RV cannot generate a tall R in V1 through a thick cushion of low-density emphysematous lung.
RV dilatation > RV hypertrophy - In COPD-related cor pulmonale, the quantum of hypertrophy is relatively modest compared to primary PAH or critical mitral stenosis. The RV dilates more than it hypertrophies, and dilation shifts forces posteriorly (away from V1) rather than anteriorly.

As Harrison's notes: "Chronic cor pulmonale due to obstructive lung disease usually does not produce the classic ECG patterns of right ventricular hypertrophy. Instead of tall right precordial R waves, emphysema is more typically associated with diminished r waves in right to mid-precordial leads (slow R-wave progression) due in part to downward displacement of the diaphragm and the heart. Low-voltage complexes are commonly present, owing to hyperaeration." - Harrison's Principles of Internal Medicine 22E

ECG Features of Type C RVH

Direct QRS findings (the "negative" pattern):

Persistent rS or QS complexes in V1-V3 (poor R-wave progression / "SV1-SV2-SV3" pattern)
Low-voltage QRS complexes in precordial and/or limb leads
Right axis deviation (QRS axis > +90°, often + 90° to +110°)
S1-S2-S3 pattern: dominant S wave in leads I, II, and III simultaneously
Short QRS duration (sometimes < 75 ms due to LV disuse atrophy)
Clockwise rotation of the heart with delayed R/S transition zone (transition zone pushed to V5-V6 or absent)

Indirect "proxy" criteria (how you actually diagnose it):

Right atrial enlargement (P pulmonale): peaked P waves ≥ 2.5 mm in II, III, or aVF - this is your strongest clue. For all practical purposes, P pulmonale = RVH (except isolated tricuspid stenosis).
P-wave axis verticalization: P-wave axis > +60° to +75°, with inverted/flat P in lead I (the "Lead I sign")
Rightward P-wave and QRS axis together pointing to cor pulmonale

Harrison's ECG diagram showing LVH vs RVH QRS patterns in V1 and V6

Harrison's Principles of Internal Medicine 22E - FIGURE 247-9: RVH may show R, RS, or qR complex in V1 (Types A/B) with T-wave inversions, but in Type C the rS pattern persists with no dominant R.

Classic Causes of Type C RVH

COPD / Emphysema with cor pulmonale - the prototype. Chronic hypoxic pulmonary vasoconstriction causes slowly progressive RV pressure and volume overload with dilatation. The emphysematous lung insulates and displaces the heart.
Acute cor pulmonale (massive pulmonary embolism) - acutely, the RV cannot generate tall R waves in the timescale of hours. The S1Q3T3 pattern may co-exist. Type C in this context reflects acute RV dilatation under sudden pressure load.
Interstitial lung disease with pulmonary hypertension - similar mechanism to COPD.

Clinical Importance - Why Type C RVH Matters

1. You can miss it if you look only for tall R in V1. Many clinicians only screen for the Type A pattern and miss Type C entirely. In a COPD patient, the absence of tall R waves does NOT exclude significant RVH/cor pulmonale.

2. It helps differentiate chronic vs. acute RV disease. A classic clinical scenario: a patient presents with acute dyspnea and RV dilatation on echo, with a filling defect in the pulmonary artery.

Type A RVH on ECG (tall monophasic R in V1) = the RV has had time to hypertrophy = chronic PAH (e.g., in-situ thrombus from PAH, not acute PE)
Type C RVH on ECG (poor R progression, no tall R) = acute or subacute process, favoring acute massive PE where the RV hasn't had time to develop hypertrophy

This distinction can guide management between thrombolysis vs. anticoagulation-only approaches.

3. Confounds anterior MI interpretation. The persistent QS or rS pattern in V1-V3 can mimic anterior wall myocardial infarction (poor R-wave progression = pseudoinfarct pattern). Always correlate with clinical history and biomarkers.

Summary Table: Type C RVH at a Glance

Feature	Finding
V1 morphology	rS or QS (no dominant R)
QRS axis	Right (+90° to +110° or beyond)
P wave	Peaked (P pulmonale), rightward axis (P-wave verticalization)
Precordial voltage	Low, especially left-sided (V4-V6)
R-wave progression	Poor or absent (SV1-SV2-SV3 pattern)
S1-S2-S3	Often present
Clockwise rotation	Transition zone delayed to V5-V6 or not reached
Key indirect sign	Right atrial enlargement (P pulmonale)
Prototype cause	COPD/emphysema, acute massive PE
Mechanism	RV dilatation + pulmonary insulation + heart displacement

Bottom line: Type C RVH is RVH without its classical fingerprint. The RV is under stress, but the ECG evidence is "masked" by pulmonary hyperinflation, dilatation rather than true hypertrophy, and inferior displacement of the heart. Look for P pulmonale, right axis deviation, and poor R-wave progression together in the appropriate clinical context (COPD, acute PE) - that constellation IS your Type C RVH diagnosis.

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