Critical Care Medicine-Neurologic Disorders>>>>>Arrhythmias and Pacemaker
Question 4#

A 95-year-old female develops bradycardia in the postanesthesia care unit shortly after having undergone a transcatheter aortic valve replacement (TAVR). ECG shows a heart rate of 41, and a thirddegree atrioventricular block (AVB) is noted. A preoperative ECG showed normal sinus rhythm, right bundle branch block (RBBB), and signs of left ventricular hypertrophy. Her blood pressure up to this point had been normal but now is 93/53 mm Hg. She does report mild dizziness but appears otherwise neurologically intact.

Which of the following statements is TRUE?

A. Most of the patients after TAVR require a lifelong permanent pacemaker (PPM)
B. Immediate TCP is indicated for TAVR-induced third-degree AVB
C. A preoperative RBBB in patients undergoing TAVR is associated with worse outcomes
D. Dopamine and isoproterenol are not efficacious in this situation
E. Aminophylline is recommended for this patient with a third-degree AVB

Correct Answer is C

Comment:

Correct Answer: C

Conduction system abnormalities are common after TAVR. A new-onset left bundle branch block occurs in 19% to 55% and a new high-degree AVB in approximately 10% of patients. Up to 50% of these new-onset conduction disturbances resolve before discharge. Further, only 50% of patients with a new PPM after TAVR will be pacer dependent at 6 to 12 months. In older studies, up to 51% of patients received PPM implant after TAVR, but owing to evolving technology, there has been a significant decrease in the need for pacemaker implantation after TAVR.

Although it is imperative to place TCP pads on this patient, this patient appears hemodynamically and neurologically fairly intact and thus an attempt at chemical pacing is reasonable. Hemodynamic instability and bradycardia refractory to medical therapy (including atropine and sympathomimetics) warrant transcutaneous or transvenous pacing. Preprocedural conduction abnormalities, particularly RBBB is associated with increased risk of PPM and death after TAVR.

Beta-adrenergic agonists such as isoproterenol, dopamine, dobutamine, and epinephrine enhance atrioventricular nodal and His-Purkinje conduction, and automaticity of atrioventricular junctional and ventricular pacemakers in the setting of a complete AVB. Clinical efficacy of dopamine was shown to be equivalent to TCP in patients with unstable bradycardia unresponsive to atropine. Isoproterenol was able to elicit an escape rhythm in the majority of pacemaker-dependent patients. Use of aminophylline is reasonable for patients with a second- or third-degree AVB associated with acute inferior myocardial infarction.

References:

1. Kusumoto FM, Schoenfeld MH, Barrett C, et al. 2018 ACC/AHA/HRS Guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay: a report of the American College of Cardiology/American Heart Association task force on clinical practice guidelines and the heart rhythm society. Heart Rhythm. 2018doi:10.1016/j.hrthm.2018.10.037.
2. Piazza N, Onuma Y, Jesserun E, et al. Early and persistent intraventricular conduction abnormalities and requirements for pacemaking after percutaneous replacement of the aortic valve. JACC Cardiovasc Interv. 2008;1:310-316.
3. Auffret V, Webb JG, Eltchaninoff H, et al. Clinical Impact of baseline right bundle branch block in patients undergoing transcatheter aortic valve replacement. JACC Cardiovasc Interv. 2017;10:1564-1574.
4. Gonska B, Seeger J, Kessler M, et al. Predictors for permanent pacemaker implantation in patients undergoing transfemoral aortic valve implantation with the Edwards Sapien 3 valve. Clin Res Cardiol. 2017;106:590-597.