Examkin

Question

Difficulty: HardCardiovascular System

Match each distinct electrocardiographic (ECG) finding with its most characteristic underlying structural or anatomical pathology.

  • Electrical alternans with concurrent sinus tachycardiaAccumulation of fluid within the pericardial sac
  • Epsilon waves in right precordial leads (V1-V3) with T wave inversionsFibrofatty replacement of the right ventricular myocardium
  • Slurred initial upstroke of the QRS complex with a shortened PR intervalPresence of an accessory atrioventricular conduction tract
  • Deep, narrow ("dagger-like") Q waves in lateral and inferior leadsAsymmetric septal hypertrophy causing dynamic outflow obstruction
  • Broad, notched P waves in lead II accompanied by right axis deviationRheumatic valvular thickening with secondary pulmonary hypertension

Answer

Electrical alternans aligns with pericardial fluid accumulation; Epsilon waves align with fibrofatty RV replacement; Slurred QRS upstroke aligns with an accessory tract; Deep narrow Q waves align with asymmetric septal hypertrophy; Broad notched P waves with right axis deviation align with rheumatic valvular thickening with secondary pulmonary hypertension.
Each matching pair requires translating a surface electrical anomaly into its specific pathophysiological or anatomical driver. Pericardial fluid allows the heart to swing, altering the electrical axis beat-to-beat (alternans). Fibrofatty infiltration in the RV delays local depolarization, creating a post-QRS blip (Epsilon wave). An accessory pathway creates a fast-track bypass around the AV node, causing early ventricular excitation (short PR, slurred upstroke). A massively hypertrophied septum generates an exaggerated left-to-right depolarization vector, carving deep but narrow Q waves in lateral leads. Finally, a stenotic mitral valve causes upstream left atrial dilation (P mitrale) and eventual pulmonary hypertension, which in turn causes right ventricular hypertrophy (right axis deviation).

Step-by-Step Solution

1
Analyze the first ECG pattern: Electrical alternans.
Identify it as alternating QRS amplitudes due to mechanical shifting of the heart.
This physical swinging specifically requires a large fluid collection in the pericardial space.
2
Evaluate the second finding: Epsilon waves in V1-V3.
Recognize this as a sign of delayed right ventricular depolarization.
This delay is pathognomonic for structural disruption, specifically the fibrofatty replacement seen in arrhythmogenic right ventricular cardiomyopathy (ARVC).
3
Assess the third finding: Slurred QRS upstroke and short PR interval.
Identify the pattern as pre-excitation (delta wave).
Pre-excitation occurs when electrical impulses bypass the slow AV node via a congenital accessory atrioventricular tract.
4
Analyze the fourth finding: Deep, narrow Q waves in lateral/inferior leads.
Differentiate these from infarction Q waves because they are narrow, representing massive normal septal depolarization.
This electrical exaggeration is the direct result of asymmetric septal hypertrophy.
5
Synthesize the final findings: Broad notched P waves and right axis deviation.
Correlate P mitrale with left atrial enlargement and right axis deviation with right ventricular hypertrophy.
This specific bi-chamber pressure overload is the classic hemodynamic sequence of rheumatic mitral stenosis leading to pulmonary hypertension.

Key Concept

Correlation of distinct electrocardiographic (ECG) patterns with their primary underlying structural, anatomical, or histological myocardial pathologies.
Rate this question

Topics

Cardiovascular System

More questions from this topic