A 63-year-old man presents to your office for a check-up. On cardiac examination, you notice an irregular rhythm. The patient walks two miles every day and has no significant dyspnea. A 12-lead electrocardiogram shows a Mobtiz type II second degree atrioventricular (AV) block, as well as a left bundle-branch block. The patient asks what, if anything, needs to be done, since he has no symptoms.
Which of the following statements concerning the patients AV conduction abnormality is most accurate?
A. A pacemaker is not indicated because he is asymptomatic B. A pacemaker is not indicated because this is a stable rhythm C. A pacemaker is indicated in a type II AV block when a wide QRS is present D. A pacemaker is indicated in all type II AV blocks
A pacemaker is indicated in a type ii av block when a wide qrs is present-key concept/objective: to understand that type ii av block is an indication for pacing regardless of symptoms when associated with a wide qrs complex high-degree (or advanced) type ii av block is defined as block of two or more consecutive p waves. complete heart block, or third-degree block, denotes a complete absence of conduction from the atria to the ventricles. in advanced or complete heart block, there is often an escape rhythm that can originate from the area of the av node (which generally results in a narrow qrs with typical escape rate 50 to 60 beats/min) or from one of the ventricles (wide qrs with typical escape rate 30 to 40 beats/min). a hallmark of complete heart block with escape rhythm is a regular ventricular rate. the anatomic location of av block has important prognostic and therapeutic implications. typically, a block occurring at the level of the av node-such as first-degree block, type i second-degree block, and 2:1 block at the level of the av node-does not lead to abrupt complete heart block, though gradual progression is common. a block occurring below the level of the av node, on the other hand, can often progress quickly to complete heart block. in addition, high-degree or complete heart block at the level of the av node is more likely to be ameliorated by an escape rhythm, whereas block at the level of the his-purkinje system is associated with a greater risk of complete ventricular asystole. pacing is indicated in second-degree av block, regardless of type, when associated with symptomatic bradycardia. type ii second-degree av block is also an indication for pacing when associated with a wide qrs complex, regardless of symptoms, because it likely indicates his-purkinje system disease.