AV Blocks PDF

ARRHYTHMIAS: AV Blocks Ateneo de Davao University School of Nursing By: Rachel Fuentes-Noe, RN, MN Atrioventricular (AV) block is partial or complete interruption of impulse transmission from the atria to the ventricles The most common causes of AV block are Idio...

ARRHYTHMIAS: AV Blocks Ateneo de Davao University School of Nursing By: Rachel Fuentes-Noe, RN, MN Atrioventricular (AV) block is partial or complete interruption of impulse transmission from the atria to the ventricles The most common causes of AV block are Idiopathic fibrosis and sclerosis of the conduction system (about 50% of patients) Ischemic heart disease (40%)  Medications (eg, beta-blockers, calcium The channel blockers, digoxin, amiodarone) remaining Increased vagal tone cases of AV block are Valvulopathy caused by Congenital heart, genetic, or other disorders First Degree AV Block All normal P waves are followed by QRS complexes, but the PR interval is longer than normal (> 0.20 second) Rate 60 bpm Rhythm regular P wave normal PR interval 0.32 sec QRS 0.08 sec Interpretation: FIRST DEGREE AV BLOCK Second Degree AV Block Some normal P waves are followed by QRS complexes, but some are not. Two types Mobitz type I Mobitz type II Mobitz type I the PR interval progressively lengthens with each beat until the atrial impulse is not conducted and the QRS complex is dropped (Wenckebach phenomenon); AV nodal conduction resumes with the next beat, and the sequence is repeated Rate 60 bpm Rhythm regularly irregular P wave present, 1-2 before QRS PR interval 0.2 - 0.36 sec (progressively lengthens) QRS 0.08 sec, skipped every after 3 beats Interpretation: MOBITZ I AV BLOCK Mobitz type II the PR interval remains constant. Beats are intermittently nonconducted and QRS complexes dropped, usually in a repeating cycle of every 3rd (3:1 block) or 4th (4:1 block) P wave Rate 60 bpm Rhythm regularly irregular P wave normal, present PR interval 0.12 sec QRS 0.08 sec, skipped every after 3 beats Interpretation: MOBITZ II 2ND DEGREE AV BLOCK Third-degree AV block Heart block is complete There is no electrical communication between the atria and ventricles and thus no relationship between P waves and QRS complexes (AV dissociation). Cardiac function is maintained by an escape junctional or ventricular pacemaker. Rate 60 atrial bpm (ventricular 30 bpm) Rhythm irregular P wave normal with constant P-P intervals, but not "married" to the QRS PR interval random QRS wide Interpretation: THIRD DEGREE AV BLOCK THANK YOU! RPF