Single chamber or dual chamber pacemaker? Cardiology Basics

Single chamber or dual chamber pacemaker? Cardiology Basics

The decision between single chamber and dual chamber pacemaker though important based on cost, device longevity and complication wise, is not that easy to make. I am trying to summarize based on the 2018 American College of Cardiology/American Heart Association/Heart Rhythm Society guidelines on this aspect [1]. In underprivileged regions, given an option, there is always a potential bias towards single chamber devices as they are cheaper, tend to have more battery life, easier to implant and likely to have lesser procedure and lead related issues.

In symptomatic sinus node dysfunction, with correlation between symptoms and bradycardia, permanent pacing is a Class I indication. There is no cutoff of heart rate or length of pause as an indication for pacing in sinus node dysfunction. If need for pacing is likely to  very infrequent or the patient has significant comorbidities reducing survival, single chamber ventricular pacing has been given a Class IIa recommendation in symptomatic sinus node dysfunction.

In others, AV conduction has to be assessed and check whether there is a reason to avoid a right ventricular lead as borderline left ventricular function. If AV conduction is intact and there is reason to avoid an RV lead, single chamber atrial pacing has been given a Class I recommendation. Atrial based pacing can lower the chance of atrial fibrillation. It may be noted that even in those with currently intact AV conduction, there is a small chance to deterioration later, which can be tackled with pacemaker revision if needed. Right ventricular pacing can potentially lead to worsening of left ventricular function in the long run, due to left ventricular dyssynchrony.

On the other hand, if there is no reason to avoid an RV lead and there is chance of deterioration of AV conduction, dual chamber pacing has been given a Class I recommendation. Programming to minimize ventricular pacing has been given a Class IIa recommendation in this group. It may also be noted that benefit of pacing in sinus node dysfunction is mainly improvement in quality of life.

Permanent pacing is also recommended when guideline directed medical therapy for other conditions produce symptomatic sinus bradycardia as with beta blockers and calcium channel blockers. This is considered when there is no alternative treatment for the other condition is available. Permanent pacing in that situation permits safe continuation of medications with negative chronotropic effects.

Symptomatic AV block is another important reason for implantation of pacemaker. In case of infranodal disease, even asymptomatic cases need pacing as there a risk of sudden onset complete AV block, syncope and harm. In patients with acquired second degree Mobitz type II AV block, high grade AV block or complete AV block which are not due to reversible causes, permanent pacing has been given a Class I recommendation.

In patients with sinus node dysfunction and AV block who need permanent pacing, dual chamber pacing is recommended over single chamber ventricular pacing as a Class I recommendation. In certain patients with AV block needing pacing, if the frequency of pacing is likely to low or if there are significant comorbidities, single chamber ventricular pacing has a Class I recommendation.

Patients in sinus rhythm with AV block who develop pacemaker syndrome while on single chamber ventricular pacemaker needs revision to a dual chamber pacemaker as a Class I indication. Atrial lead should not be implanted in a person with persistent atrial fibrillation if a rhythm control strategy is not being planned (Class III). So that is also an indication for single chamber ventricular pacing.

Advanced pacing options like cardiac resynchronization therapy and His bundle pacing in patients with AV block have also been covered in the guidelines. They are considered in those with borderline left ventricular function and likely need for pacing more than 40% of the time. His bundle pacing can be considered in those with AV block in the region of the AV node also. This is a highly abridged version and those who wish to have more information, please read the full text of the guidelines available as free full text online.

Reference

1. Kusumoto FM, Schoenfeld MH, Barrett C, Edgerton JR, Ellenbogen KA, Gold MR, Goldschlager NF, Hamilton RM, Joglar JA, Kim RJ, Lee R, Marine JE, McLeod CJ, Oken KR, Patton KK, Pellegrini CN, Selzman KA, Thompson A, Varosy PD. 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. J Am Coll Cardiol. 2019 Aug 20;74(7):e51-e156. doi: 10.1016/j.jacc.2018.10.044. Epub 2018 Nov 6. Erratum in: J Am Coll Cardiol. 2019 Aug 20;74(7):1016-1018. PMID: 30412709.