0071643192.pdf

■ First-degree AV block

■ Second-degree AV block type I (Wenckebach, Mobitz I)

■ Second-degree AV block type II (Mobitz II)

■ Third-degree AV block (complete heart block)

INTRAVENTRICULARBLOCKS

■ Unilateral fascicular blocks

■ Right bundle branch block (RBBB)

■ Left anterior fascicular block (LAFB)

■ Left posterior fascicular block (LPFB)

■ Bifascicular blocks

■ RBBB+LAFPorLPFB

■ Left bundle branch block (LBBB)

■ Trifascicular blocks

■ Any bifascicular block +first-degree AV block

■ Alternating RBBB and LBBB

FIRST-DEGREEAV BLOCK

First-degree AV block is common and is often a normal variant in a healthy

heart. It results from prolonged conduction of the atrial impulse, typically at the

AV node.

CAUSES

Causes include:

■ Increased vagal tone in healthy heart

■ ACS (usually inferior MI)

■ Infectious disease (eg, Lyme disease, rheumatic fever)

■ Infiltrative myocardial disease (eg, sarcoidosis)

■ Structural heart disease (congenital or surgical)

■ Medications

ECG FINDINGS(SEEFIGURE1.3)

■ All P waves conducted (QRS for every P wave)

■ PR interval > 0.2 seconds

■ PR interval constant

TREATMENT

■ Doesnotcause serious signs or symptoms

■ Treat underlying condition.

RESUSCITATION

FIGURE 1.3. First-degree AV block.

(Reproduced, with permission, from Tintinalli JE, Kelen GD, Stapczynski JS. Emergency

Medicine: A Comprehensive Study Guide, 6th ed. New York: McGraw-Hill, 2004:193.)