ECG Interpretation Flashcards

Right bundle branch block (RBBB) produces which classic ECG pattern?

Answer: RSR' (rabbit ears) pattern in V1 and wide S waves in leads I, aVL, and V6

RBBB produces the classic RSR' (M-shaped or rabbit ears) pattern in V1-V2 and wide, slurred S waves in I, aVL, V5-V6 due to delayed right ventricular activation.

The QTc (corrected QT) is used to adjust for heart rate. Using Bazett's formula, QTc is prolonged when it exceeds which threshold in adults?

Answer: 440-450 ms (with upper limits: 450 ms in men, 460 ms in women)

QTc greater than 440-450 ms in men or 460-470 ms in women is generally considered prolonged, with QTc > 500 ms carrying the highest risk for torsades de pointes.

Wolff-Parkinson-White (WPW) syndrome produces which classic triad of ECG findings?

Answer: Short PR interval (< 120 ms), delta wave (slurred QRS upstroke), and wide QRS complex

WPW is characterized by a short PR interval (accessory pathway bypasses AV nodal delay), delta wave (early pre-excitation of the ventricle producing slurred QRS onset), and widened QRS (fusion of pre-excited and normally conducted ventricular activation).

In a patient with suspected hyperkalemia, which ECG finding appears first as potassium rises from normal levels?

Answer: Peaked, narrow, symmetric T waves

The earliest ECG sign of hyperkalemia is peaked, narrow, symmetric (tent-shaped) T waves, appearing when serum potassium rises above approximately 5.5-6.0 mEq/L.

Brugada syndrome is associated with which pattern on ECG?

Answer: Coved ST elevation in V1-V3 (Type 1 Brugada pattern) with right bundle branch block morphology

Brugada syndrome is diagnosed by the Type 1 pattern: coved (downsloping) ST elevation ≥ 2 mm in V1-V3 with RBBB-like morphology, associated with risk of sudden cardiac death from polymorphic VT/VF.

The axis of the heart on a 12-lead ECG is considered to have left axis deviation when it falls within which range?

Answer: -30 degrees to -90 degrees (or beyond -30 to -180 degrees depending on criteria)

Left axis deviation (LAD) is defined as a frontal plane QRS axis more negative than -30 degrees, producing a predominantly positive QRS in lead I and negative QRS in lead aVF.