An ECG rhythm strip shows a regular ventricular rhythm at a rate of 30 beats/min,more P waves than QRS complexes (the P waves occur regularly),a variable PR interval,and a QRS duration of 0.14 seconds.This rhythm is _____.
A) 2:1 AV block
B) third-degree AV block
C) second-degree AV block type I
D) second-degree AV block type II

Question

Quizplus · Accepted Answer

With a third-degree block,the ventricular and atrial rhythms are regular; however,AV dissociation is present.The ventricular rate is determined by the origin of the escape rhythm.Based on the description provided (i.e.,a QRS duration of 0.14 seconds and a ventricular rate of 30 beats/min),the escape pacemaker is probably ventricular in origin.P waves are normal in size and shape,but some P waves are not followed by a QRS complex.There is no true PR interval because the atria and the ventricles beat independently of each other.The QRS may be narrow or wide,depending on the location of the escape pacemaker and the condition of the intraventricular conduction system.

An ECG Rhythm Strip Shows a Regular Ventricular Rhythm at a Rate