Right Ventricular Hypertrophy RVH ECG Interpretation Made Easy

Right ventricular hypertrophy (RVH) results from pressure overload on the right side of the heart. The right ventricle normally has a thinner wall and is more compliant than the left ventricle. RVH can occur as an isolated condition or more commonly as a consequence of left ventricular pathology. The most frequent cause is pulmonary hypertension, which increases afterload on the right ventricle, leading to compensatory hypertrophy and eventual dilation. Causes of pulmonary hypertension include parenchymal lung diseases (COPD, emphysema, interstitial fibrosis), occupational lung diseases (pneumoconioses, bronchiectasis), vascular causes (thromboembolism), neuromuscular disorders, and obesity-related respiratory dysfunction.

Right ventricular hypertrophy (RVH) is characterized by enlargement of the right ventricle, which can be detected through clinical examination and imaging. The right ventricle is normally smaller than the left ventricle, so significant enlargement suggests increased pressure or volume load on the right side of the heart, often due to pulmonary hypertension or chronic lung disease. Pulmonary hypertension causes increased pressure in the pulmonary arteries, which leads to right ventricular strain and eventual hypertrophy. The right ventricle must work harder to pump blood against the elevated pulmonary vascular resistance.

Pulmonary hypertension has multiple etiologies. Group 1 includes idiopathic, hereditary, drug-induced (amiodarone, fenfluramine, rapeseed oil, vitamin B6, tryptophan, interferon alpha/beta), connective tissue disease-associated (systemic sclerosis, lupus), HIV-associated, portal hypertension-associated, congenital heart disease-associated, schistosomiasis-associated, and PAH responsive to calcium channel blockers. Group 2 includes chronic heart failure, valvular pathology, and left ventricular dysfunction. Group 3 includes COPD, interstitial lung disease, and lung developmental abnormalities. Group 4 includes chronic thromboembolic pulmonary hypertension and vasculitis. Group 5 includes hematological and metabolic disorders. Women are affected approximately twice as often as men. Associated conditions include HIV infection, portal hypertension, liver diseases, antiphospholipid syndrome, protein C deficiency, and congenital heart diseases with left-to-right shunts.

Right ventricular hypertrophy (RVH) is characterized by increased voltage in the right ventricular leads. The key diagnostic criteria include: (1) increased R-wave amplitude in V1 and V2, (2) decreased R-wave amplitude in V5 and V6, (3) right axis deviation, (4) S-wave in V5 and V6 greater than 30mm. Chronic obstructive pulmonary disease (COPD) is characterized by specific ECG findings related to cor pulmonale. The key diagnostic features include: (1) right axis deviation, (2) right ventricular hypertrophy, (3) right bundle branch block, (4) low voltage QRS complexes, (5) T-wave inversion in the precordial leads. The combination of RBBB and RVH is commonly seen in patients with COPD and cor pulmonale.

The most common causes of pulmonary hypertension are left heart diseases (50% of cases) including systemic hypertension, diabetes, heart failure, and post-infarction conditions, and chronic lung diseases (45% of cases) particularly fibrosis and emphysema. Together, these account for 95% of cases. Rare causes include: (1) Congenital heart diseases (third or fourth most common cause); (2) Connective tissue diseases like lupus and scleroderma; (3) Idiopathic pulmonary hypertension (no defined cause); (4) Asthma (approximately 15% of severe asthmatics may develop pulmonary hypertension due to inadequate oxygenation from repeated airway inflammation). The clinical approach involves identifying the underlying cause and referring to specialists for rare etiologies.

Two high-yield conditions present with distinctive ECG patterns. Pulmonary embolism shows S1Q3T3: deep S-wave in lead I, deep Q-wave in lead III, and inverted T-wave in lead III, reflecting acute right heart strain. Hypokalemia produces prominent U-waves exceeding T-wave height. Both conditions are high-yield for boards because they appear in questions testing electrolyte-pathophysiology correlations. The approach involves using answer choices to guide ECG interpretation—for example, if pulmonary embolism is an option, specifically look for S1Q3T3.

Right ventricular pressure overload produces the S1Q3T3 pattern (S in I, Q in III, T inversion in III) reflecting delayed right ventricular depolarization and abnormal repolarization. Acute pulmonary embolism commonly shows sinus tachycardia, with T-wave inversions in V1-V3 appearing on days 2-3. Additional findings include RBBB, right axis shift, and right atrial abnormality. U-waves are non-specific but prominent ones indicate hypokalemia, bradycardia, or QT prolongation, commonly seen with ST depression and T-wave flattening.

Diagnosing pulmonary embolism requires systematic investigation. Chest X-ray typically appears normal but may show enlarged pulmonary artery, wedge-shaped opacities, elevated hemidiaphragm, or pleural effusion. ECG may reveal sinus tachycardia (50% of cases), right ventricular strain patterns (inverted T-waves in V1-V4), or S1Q3T3 pattern. CT pulmonary angiogram is the gold standard for confirmation. Additional tests include V/Q perfusion scanning, bedside echocardiogram, and D-dimer assay, which helps rule out PE when negative.

ECG interpretation is critical in shock management. Cardiogenic shock shows ST elevation in AVL/V1-V4, electrical alternance (pericardial effusion), right axis deviation, T-wave inversions, and S1Q3T3 pattern. Massive pulmonary embolism causes acute RV strain: right axis deviation, T-wave inversions progressing from V1 to V4, and S1Q3T3 pattern. However, S1Q3T3 is NOT specific—it also occurs in status asthmaticus, ARDS, and tension pneumothorax. Right ventricular dysfunction causes inability to generate adequate pressure against obstruction. Recognizing these patterns guides urgent interventions like pericardiocentesis or thrombolysis.

Pulmonary embolism symptoms depend on embolus size: Massive PE causes hypotension, syncope, and cyanosis. Sinus tachycardia is most common ECG finding; S1Q3T3 pattern occurs in only 7-10%. Right heart strain shows right axis deviation, RBBB, and inverted T waves in V1-V3. Hampton hump suggests infarction; Westermark sign indicates acute embolism.

Pediatric ECG changes reflect postnatal cardiac adaptation. In utero, fetal circulation shunts blood through foramen ovale and ductus arteriosus due to high pulmonary resistance, creating right ventricular dominance. At birth, pulmonary vascular resistance drops dramatically while systemic resistance rises, reversing pressure loads so left ventricle becomes dominant. Over weeks to months, progressive pulmonary vasodilation causes gradual shift from right to left ventricular dominance. This explains why pediatric ECGs show progressively leftward axis with age, with QRS axis shifting from +75-+140° in newborns toward adult norms. Understanding this developmental sequence is essential for proper pediatric ECG interpretation.

Pediatric ECG differs from adult due to fetal circulation: right axis deviation and RV dominance are normal in newborns up to 6 months, maximum 8 years. T wave inversion in V1 is normal from 5-6 days and should not become positive before 6-7 years; upright T in V1 after 1 year suggests RVH or pulmonary hypertension. ECG findings in structural defects: Tetralogy of Fallot, TGA, truncus arteriosus, and tricuspid atresia all show RVH and right axis deviation (cannot differentiate). ASD secundum shows right axis deviation; ASD primum shows left axis deviation. VSD shows left axis deviation (LVH). Eisenmenger syndrome shows right axis deviation with P pulmonale and RVH. Hypoplastic left heart syndrome shows RVH. Coarctation of aorta shows left axis deviation or LVH.

This segment covers ventricular dominance assessment and endocardial cushion defects: (1) Ventricular dominance is assessed by examining precordial lead QRS polarity; (2) Right ventricular dominance shows negative V1-V4 and positive V5-V6; (3) Extreme axis deviation (northwest axis) shows negative QRS in both lead I and aVF; (4) Endocardial cushion defects involve abnormal development of the atrioventricular valves and lower ventricular septum; (5) These defects produce characteristic ECG patterns. The segment emphasizes distinguishing normal ventricular dominance from pathological hypertrophy.

Normal newborn EKG axis is right axis due to right ventricular predominance. To determine axis, examine leads I and aVF: if the main deflections point in the same direction, it is right axis; if they point in opposite directions, it is left axis. The normal range for newborns is approximately -30 to +90 degrees. Right ventricular strain or dysfunction on EKG is identified by: decreased R wave amplitude in right precordial leads (V1, V2, V3) and increased S wave amplitude in left precordial leads (V5, V6). The RS ratio in V1-V3 can help assess right ventricular function.

Children's ECGs differ from adults due to circulatory system restructuring (right to left ventricular predominance), heart position changes (diaphragm to descending), and maturation of neurohumoral regulatory mechanisms and cardiac conduction system. Normal variants include sinus tachycardia (120-160 bpm in newborns, 70-90 bpm in older children), junctional rhythm, wandering atrial pacemaker, low voltage in first 5-10 days, rightward axis deviation in ages 1-3, shorter PR/QRS/QT intervals with gradual increase toward adult norms, and right bundle branch block patterns. P pulmonale (high peaked P wave) is normal in newborns due to right ventricular predominance. Deep Q waves in III and aVF may persist until adolescence. Negative T waves in V1-V4 are normal until ages 10-15. Bradycardia thresholds: less than 80 bpm in newborns, less than 60 bpm in older children. Tachycardia requires investigation if not related to anxiety. Sinus tachycardia shows P wave before each QRS, shortened PR intervals (differences <0.15s), and normal QRS morphology. Sinus bradycardia shows prolonged PR intervals, P wave before QRS, and normal QRS, common in athletes and vagotonic individuals. Sinus arrhythmia shows irregular rhythm with PR interval differences >0.15s, caused by autonomic imbalance during growth periods.