ECG Troubleshooting Flashcards

An ECG shows a wide complex tachycardia at 180 bpm with AV dissociation. What is the most likely diagnosis?

Answer: Ventricular tachycardia

AV dissociation (P waves marching through QRS independently) in a wide complex tachycardia is a hallmark of ventricular tachycardia.

When recording a right-sided ECG (V3R-V6R), what is the primary clinical indication?

Answer: Suspected right ventricular MI in the setting of inferior STEMI

Right-sided leads are obtained when inferior STEMI is present to detect right ventricular involvement, which changes management (avoid nitrates and diuretics).

A patient's ECG shows a QRS duration of 140 ms with a broad, notched R wave in leads I, aVL, V5, and V6, and absence of septal Q waves. What is the diagnosis?

Answer: Left bundle branch block

Left bundle branch block (LBBB) produces broad, notched R waves (M-shaped) in lateral leads (I, aVL, V5-V6) with absent septal Q waves and QRS ≥ 120 ms.

What is the most common cause of pseudo-Q waves (QS pattern) in leads V1-V2 in an otherwise healthy patient?

Answer: Incorrect precordial electrode placement (too high)

Placing V1 and V2 electrodes one or two intercostal spaces too high is the most common technical cause of QS patterns mimicking anteroseptal infarction.

A patient on digoxin therapy has an ECG showing scooped ST depression in lateral leads, shortened QT, and slow ventricular rate. What is the most likely finding?

Answer: Digitalis effect (therapeutic digoxin changes)

The digitalis effect refers to the characteristic scooped (reverse tick) ST depression, QT shortening, and bradycardia seen with therapeutic digoxin levels.

Which ECG pattern is described as 'strain pattern' and in which condition is it most commonly seen?

Answer: Asymmetric ST depression with T wave inversion in lateral leads; LVH with pressure overload

LVH strain pattern consists of asymmetric ST depression and T wave inversion in lateral leads (I, aVL, V5-V6), reflecting subendocardial ischemia from increased wall stress.

A 45-year-old presents with syncope. The ECG shows a right bundle branch block with ST elevation in V1-V3 resembling a 'coved' pattern. What syndrome should be suspected?

Answer: Brugada syndrome

The coved-type ST elevation in V1-V3 with RBBB morphology is the classic Type 1 Brugada pattern, associated with risk of sudden cardiac death from ventricular fibrillation.