What is the treatment for pacing to regulate heart rhythm?

Treatment for Cardiac Pacing to Regulate Heart Rhythm

Permanent pacemaker implantation is the definitive treatment for cardiac pacing, with specific indications based on the underlying rhythm disorder, and the choice of pacing mode (AAI, DDD, or VVI) depends on whether the patient has sinus node dysfunction, AV block, or chronic atrial fibrillation. 1

Primary Indications for Permanent Pacemaker Implantation

Atrioventricular (AV) Block

• Permanent pacing is indicated for advanced second-degree or third-degree AV block associated with symptomatic bradycardia, ventricular dysfunction, or low cardiac output 2
• Pacing is indicated for third-degree and advanced second-degree AV block with symptomatic bradycardia, asystole >3 seconds, or escape rhythm <40 bpm 1
• For postoperative AV block, permanent pacing is indicated when block persists at least 7 days after cardiac surgery and is not expected to resolve 2
• Pacing prevents recurrence of syncope and improves survival in patients with AV block 1

Sinus Node Dysfunction (SND)

• Permanent pacemaker implantation is indicated for SND with correlation of symptoms during age-inappropriate bradycardia 2
• The primary criterion is concurrent observation of symptoms (syncope, presyncope, fatigue) with documented bradycardia (heart rate <40 bpm or asystole >3 seconds) 2
• Correlation of symptoms with bradycardia must be determined by ambulatory ECG or implantable loop recorder before proceeding with permanent pacing 2

Reflex-Mediated Syncope

• Permanent pacing is indicated for recurrent syncope caused by carotid sinus stimulation that induces ventricular asystole >3 seconds 2
• For vasovagal syncope, permanent pacing may be considered for significantly symptomatic patients with documented bradycardia or asystole, but evidence is conflicting 2
• Pacing should be confined to highly selected patients over 40 years with severe recurrent vasovagal syncope showing prolonged asystole during ECG recording or tilt testing, after failure of other therapeutic options 2

Optimal Pacing Mode Selection

For Sinus Node Dysfunction

• Atrial-based pacing (AAI or DDD) is strongly preferred over ventricular pacing (VVI) as it significantly reduces stroke risk (HR: 0.81) and atrial fibrillation (HR: 0.80) 1
• Dual-chamber pacing with minimization of right ventricular stimulation is recommended to avoid ventricular desynchronization 2
• Rate-responsive pacing (RR) should be programmed to maintain physiologic heart rates during activity 2

For AV Block with Normal Sinus Function

• DDD pacing is preferred to maintain AV synchrony and optimize cardiac output 1
• This mode preserves the atrial contribution to ventricular filling and maintains chronotropic competence 2

For Chronic Atrial Fibrillation

• Patients with chronic atrial fibrillation should receive ventricular-based pacing (VVI/R) 1
• Atrial pacing provides no benefit when atrial fibrillation is permanent 2

Special Clinical Situations

Cardiac Sarcoidosis

• Pacemaker implantation is recommended even if high-grade or complete AV block reverses transiently, due to the possibility of disease progression 2
• Cardiac sarcoidosis affects the AV conduction system in up to 30% of patients with myocardial involvement 2

Cardiac Transplantation

• Permanent pacing may be considered when relative bradycardia is prolonged or recurrent and limits rehabilitation after transplantation 2
• Approximately 50% of patients show resolution of bradyarrhythmia within 6-12 months, so temporary measures should be attempted first 2

Long-QT Syndrome

• Permanent pacing combined with beta blockade is indicated for patients with pause-dependent ventricular tachycardia 2
• AAI/DDD pacing at sufficiently high rates suppresses ventricular tachyarrhythmias by preventing bradycardia-triggered events 1
• ICD therapy with overdrive suppression pacing should be considered in high-risk patients 2

Pacing for Arrhythmia Prevention and Termination

Atrial Tachyarrhythmias

• Permanent pacing is reasonable for symptomatic recurrent supraventricular tachycardia (SVT) that is reproducibly terminated by pacing when catheter ablation and/or drugs fail 2
• Atrial antitachycardia pacing (ATP) may terminate 30-60% of atrial tachyarrhythmias in selected patients, though evidence from randomized trials is conflicting 2
• When permanent antitachycardia pacemakers detect and interrupt SVT, all pacing should be done in the atrium to avoid ventricular pacing-induced proarrhythmia 2

Bradycardia-Tachycardia Syndrome

• Permanent pacing is reasonable for patients with congenital heart disease and sinus bradycardia for prevention of recurrent intra-atrial reentrant tachycardia 2
• Long-term atrial pacing at physiological rates may prevent or terminate recurrent episodes, though results remain controversial 2

Cardiac Resynchronization Therapy (CRT)

• CRT is indicated for heart failure patients with LVEF ≤35%, NYHA class III-IV symptoms despite optimal medical therapy, and QRS duration ≥120 ms (particularly with left bundle branch block) 1
• Biventricular pacing is the preferred mode, though left ventricular pacing alone may be acceptable in selected patients 1
• For patients with conventional pacemakers who develop severe LV dysfunction (LVEF ≤35%) and NYHA class III symptoms, upgrading to biventricular pacing is indicated 1

Critical Pitfalls to Avoid

• Always exclude reversible causes before permanent pacemaker implantation: drug effects (digitalis intoxication), electrolyte disturbances, inflammatory or ischemic myocardial disease 2, 1
• Do not implant permanent pacemakers for hypersensitive cardioinhibitory response to carotid sinus stimulation without documented symptoms 2
• Avoid ventricular-only pacing (VVI) in patients with sinus node dysfunction, as this increases risk of atrial fibrillation and stroke 1
• Do not use AAI-like algorithms in patients with vasovagal syncope, as they fail to pace the ventricle when needed 2
• Recognize that dual-chamber pacing with short AV delay does not improve outcomes in heart failure patients without standard bradycardia indications 3