Indications for pacemakers

# Guidelines for Implantation of a Pacemaker for Sinus Node Dysfunction

## Class I
- Sinus node dysfunction with documented symptomatic bradycardia, including frequent sinus pauses that produce symptoms. In some patients, bradycardia is iatrogenic and will occur as a consequence of essential long-term drug therapy of a type and dose for which there are no acceptable alternatives.
- Symptomatic chronotropic incompetence.

## Class IIa
- Sinus node dysfunction occurring spontaneously or as a result of necessary drug therapy with heart rate <40 bpm when a clear association between significant symptoms consistent with bradycardia and the actual presence of bradycardia has not been documented.

## Class IIb
- In minimally symptomatic patients, chronic heart rate <30 bpm while awake.

## Class III
- Sinus node dysfunction in asymptomatic patients, including those in whom substantial sinus bradycardia (heart rate <40 bpm) is a consequence of long-term drug treatment.
- Sinus node dysfunction in patients with symptoms suggestive of bradycardia that are clearly documented as not associated with a slow heart rate.
- Sinus node dysfunction with symptomatic bradycardia due to nonessential drug therapy.

# Guidelines for Implantation of a Pacemaker in Acquired Atrioventricular Block in Adults

## Class I
- Third-degree AV block at any anatomic level associated with any one of the following conditions:
Bradycardia with symptoms presumed to be due to AV block.
Arrhythmias and other medical conditions that require drugs that result in symptomatic bradycardia.
Documented periods of asystole  3.0 seconds or any escape rate <40 beats per minute (bpm) in awake, symptom-free patients.
After catheter ablation of the AV junction.
Postoperative AV block that is not expected to resolve.
Neuromuscular diseases with AV block such as myotonic muscular dystrophy, Kearns-Sayre syndrome, Erb's dystrophy (limb-girdle), and peroneal muscular atrophy.
- Bradycardia with symptoms presumed to be due to AV block.
- Arrhythmias and other medical conditions that require drugs that result in symptomatic bradycardia.
- Documented periods of asystole  3.0 seconds or any escape rate <40 beats per minute (bpm) in awake, symptom-free patients.
- After catheter ablation of the AV junction.
- Postoperative AV block that is not expected to resolve.
- Neuromuscular diseases with AV block such as myotonic muscular dystrophy, Kearns-Sayre syndrome, Erb's dystrophy (limb-girdle), and peroneal muscular atrophy.
- Second-degree AV block regardless of type or site of block, with associated symptomatic bradycardia.

## Class IIa
- Asymptomatic third-degree AV block at any anatomic site with average awake ventricular rates of 40 bpm or faster.
- Asymptomatic type II second-degree AV block.
- Asymptomatic type I second-degree AV block at intra- or infra-His levels found incidentally at electrophysiological study for other indications.
- First-degree AV block with symptoms suggestive of pacemaker syndrome and documented alleviation of symptoms with temporary AV pacing.

## Class IIb
- Marked first-degree AV block (>0.30 second) in patients with LV dysfunction and symptoms of congestive heart failure in whom a shorter AV interval results in hemodynamic improvement, presumably by decreasing left atrial filling pressure.

## Class III
- Asymptomatic first-degree AV block.
- Asymptomatic type I second-degree AV block at the supra-His (AV node) level or not known to be intra- or infra-Hisian.
- AV block expected to resolve and unlikely to recur (eg, drug toxicity, Lyme disease).

# Guidelines for Implantation of a Pacemaker in patients with chronic bifascicular or trifascicular block.

## Class I
- Intermittent third-degree AV block.
- Type II second-degree AV block.

## Class IIa
- Syncope not proved to be due to AV block when other likely causes have been excluded, specifically ventricular tachycardia (VT).
- Incidental finding at electrophysiological study of markedly prolonged HV interval ( 100 milliseconds) in asymptomatic patients.
- Incidental finding at electrophysiological study of pacing-induced infra-His block that is not physiological.

## Class IIb
- None.

## Class III
- Fascicular block without AV block or symptoms.
- Fascicular block with first-degree AV block without symptoms.

# Guidelines for Implantation of a Pacemaker in Hypersensitive Carotid Sinus and Neurally Mediated Syndromes

## Class I
- Recurrent syncope caused by carotid sinus stimulation; minimal carotid sinus pressure induces ventricular asystole of >3 seconds' duration in the absence of any medication that depresses the sinus node or AV conduction.

## Class IIa
- Recurrent syncope without clear, provocative events and with a hypersensitive cardioinhibitory response.
- Syncope of unexplained origin when major abnormalities of sinus node function or AV conduction are discovered or provoked in electrophysiological studies.

## Class IIb
- Neurally mediated syncope with significant bradycardia reproduced by a head-up tilt with or without isoproterenol or other provocative maneuvers.

## Class III
- A hyperactive cardioinhibitory response to carotid sinus stimulation in the absence of symptoms.
- A hyperactive cardioinhibitory response to carotid sinus stimulation in the presence of vague symptoms such as dizziness, light-headedness, or both.
- Recurrent syncope, light-headedness, or dizziness in the absence of a hyperactive cardioinhibitory response.
- Situational vasovagal syncope in which avoidance behavior is effective.