From the Guidelines
The treatment for a second-degree type 2 atrioventricular (AV) block typically involves permanent pacemaker implantation, as this condition often progresses to complete heart block and can cause significant symptoms. This recommendation is based on the most recent and highest quality study, which emphasizes the importance of permanent pacing in patients with acquired second-degree Mobitz type II atrioventricular block, high-grade atrioventricular block, or third-degree atrioventricular block not caused by reversible or physiologic causes 1.
Key Considerations
- The location of the conduction problem in type 2 AV block, which is in the His-Purkinje system rather than the AV node itself, explains why type 2 blocks are less responsive to atropine and more likely to progress to complete heart block, making permanent pacing the definitive treatment in most cases.
- For temporary management before pacemaker placement, atropine 0.5-1 mg IV may be administered, though it's often ineffective in this type of block, as noted in older studies 1.
- In emergency situations with symptomatic bradycardia, transcutaneous pacing can be initiated while awaiting definitive treatment, as suggested by recent guidelines 1.
- Underlying causes such as myocardial ischemia, medication effects (beta-blockers, calcium channel blockers), or electrolyte abnormalities should be identified and addressed.
Temporary Measures
- Temporary transvenous pacing is reasonable for patients with second-degree or third-degree atrioventricular block associated with symptoms or hemodynamic compromise that is refractory to medical therapy 1.
- Temporary transcutaneous pacing may be considered until a temporary transvenous or permanent pacemaker is placed or the bradyarrhythmia resolves, especially in cases of hemodynamic compromise refractory to antibradycardic medical therapy 1.
Definitive Treatment
- Permanent pacemaker implantation is the recommended treatment for second-degree type 2 AV block, given its potential to progress to complete heart block and cause significant symptoms, as emphasized by the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
From the FDA Drug Label
Atropine also may lessen the degree of partial heart block when vagal activity is an etiologic factor The treatment for a second-degree type 2 atrioventricular (AV) block may involve atropine as it can lessen the degree of partial heart block when vagal activity is an etiologic factor, however the label does not explicitly state its use for second-degree type 2 AV block 2.
From the Research
Treatment for Second-Degree Type 2 Atrioventricular (AV) Block
The treatment for second-degree type 2 atrioventricular (AV) block typically involves:
- Implantation of a pacemaker, as this condition is more likely to progress to complete heart block and Stokes-Adams arrest 3
- Catheter ablation as a treatment option for alleviating symptomatic AV block due to a ventricular nodal pathway interfering with AV conduction 4
- Pacing is required for infranodal block presenting with either type I or II manifestations, regardless of QRS duration or symptoms 5
Considerations for Treatment
When considering treatment for second-degree type 2 AV block, the following factors should be taken into account:
- The site of the block, which can be determined using information about the age of the patient, the clinical setting, and the width of the QRS complex on the surface electrocardiogram 3
- The presence of symptoms, such as palpitations and presyncopal events, which can guide treatment decisions 6
- The effectiveness of pharmacological treatment attempts, such as β-blocker, calcium channel antagonists, and ivabradine, which may remain clinically unsuccessful 6
Specific Treatment Approaches
In specific cases, the following treatment approaches may be considered:
- Prophylactic implantation of a temporary pacemaker prior to surgery, especially in symptomatic patients or those with a high risk of progression to complete AV block 7
- Radiofrequency catheter ablation of a concealed ventricular nodal pathway interfering with AV conduction, which can restore normal AV conduction and eliminate clinical symptoms 4