0071643192.pdf

ECG ESSENTIALS

Conduction Blocks

RIGHTBUNDLEBRANCHBLOCK(RBBB)

RBBB results from failure of conduction of the R bundle. R ventricular activa-
tion occurs via conduction through the L ventricle and is therefore delayed
and slowed.

CAUSES

RBBB may occur in a healthy heart but is typically caused by right-sided heart
strain:

■ Pulmonary hypertension
■ Atrial septal defect
■ Ischemia
■ COPD
■ Massive pulmonary embolism (PE)

ECG FINDINGS(SEEFIGURE2.1)

■ Characterized by terminal slurring of QRS complex
■ QRS duration ≥0.12 sec
■ Terminal R in V 1 (rR, rSR)
■ Large S wave in V 6
■ Appropriately discordant T waves—T waves deflected opposite the terminal
deflection of the QRS

TREATMENT

■ Treat underlying condition.

CARDIOVASCULAR EMERGENCIES

RBBB can occur in a healthy

heart.

II dVL V2 V5

III dVF V3 V6

FIGURE 2.1. Right bundle branch block.

Law of Appropriate

Discordance: The T waves

should be deflected opposite

the terminal deflection of the

QRS.