From the Guidelines
The treatment for second-degree type 2 (Mobitz II) atrioventricular (AV) block is permanent pacing, as recommended by the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1. This type of heart block is considered more serious than type 1 because it often progresses to complete heart block and is usually caused by disease in the His-Purkinje system.
- Key considerations for permanent pacing include:
- The presence of symptoms that correlate with atrioventricular block
- The absence of conditions associated with progressive atrioventricular conduction abnormalities
- The need for ventricular pacing >40% of the time, in which case techniques that provide more physiologic ventricular activation (e.g., cardiac resynchronization therapy, His bundle pacing) are preferred to right ventricular pacing to prevent heart failure 1 While waiting for pacemaker placement, temporary measures may include atropine (0.5-1 mg IV) for symptomatic bradycardia, though its effectiveness is limited in type 2 blocks.
- In emergency situations, transcutaneous pacing or temporary transvenous pacing may be necessary until definitive treatment. Underlying causes should be addressed, including discontinuing medications that slow AV conduction (beta-blockers, calcium channel blockers, digoxin), correcting electrolyte abnormalities, and treating ischemia if present.
- Patients should be monitored closely as this condition can deteriorate rapidly, and treatment decisions should be based on the best available evidence and on the patient’s goals of care and preferences 1.
From the Research
Treatment for Second-Degree Type 2 (Mobitz II) Atrioventricular (AV) Block
The treatment for second-degree type 2 (Mobitz II) atrioventricular (AV) block typically involves permanent pacemaker (PPM) implantation.
- Permanent pacing is usually instituted in patients who develop second-degree type II AV block to prevent sudden death from the reappearance of the heart block or asystole 2.
- PPM implantation is the standard of care in patients with second-degree type II AV block, irrespective of patient symptoms, when the conduction abnormality is irreversible 3.
- The type of pacing and the timing of electrode insertion depend on the experience of the operator and the prevailing conditions 2.
- In some cases, beta-blocker medication may be used to prevent high sinus rates during everyday activity, especially in patients with tachycardia-dependent AV block 4.
- Electrophysiologic studies (EPS) may be performed to determine the site of the AV block and to induce AV nodal reentrant tachycardia (AVNRT) 5.
Considerations for Treatment
- The distinction between type II and type I block is descriptive, but the anatomic site of the block and the prognosis are of greater importance to the clinician 6.
- Type II AV block is more likely to progress to complete heart block and Stokes-Adams arrest, making prompt treatment essential 6.
- Patients with second-degree type II AV block should be closely monitored, and PPM implantation should be considered to prevent complications 3, 5.