Paroxysmal AV block Medical Therapy
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Akash Daswaney, M.B.B.S[2]
Overview
In patients with acute onset AV block,reversible causes such as drug toxicity,thyroid dysfunction, Lyme disease, etc should be taken into consideration. A decision should then be made regarding usage of [medical]] therapy or other treatment modalities such as temporary pacing. Theophylline is an adenosine antagonist that may be used in the diagnosis of extrinsic vagal paroxysmal AV Block.
2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: Recommendations for Acute Management of Reversible Causes of Bradycardia Attributable to Atrioventricular Block
| Recommendations for Acute Management of Reversible Causes of Bradycardia Attributable to Atrioventricular Block |
| "1. Patients with transient or reversible causes of atrioventricular block, such as Lyme carditis or drug toxicity, should have medical therapy and supportive care, including temporary transvenous pacing if necessary, before determination of need for permanent pacing. (Level of Evidence: B-NR
2. In selected patients with symptomatic second-degree or third-degree atrioventricular block who are on chronic stable doses of medically necessary antiarrhythmic or betablocker therapy, it is reasonable to proceed to permanent pacing without further observation for drug washout or reversibility. (Level of Evidence: B-NR)[1] 3. In patients with second-degree or third degree atrioventricular block associated with cardiac sarcoidosis, permanent pacing, with additional defibrillator capability if needed and meaningful survival of greater than 1 year is expected, without further observation for reversibility is reasonable. (Level of Evidence: B-NR)[1] 4. In patients with symptomatic second degree or third-degree atrioventricular block associated with thyroid function abnormalities but without clinical myxedema, permanent pacing without further observation for reversibility may be considered. (Level of Evidence: C-LD)[1]" |
2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: Recommendations for Acute Medical Therapy for Bradycardia Attributable to Atrioventricular Block
| Recommendations for Acute Medical Therapy for Bradycardia Attributable to Atrioventricular Block |
| "1. For patients with second-degree or third degree atrioventricular block believed to be at the atrioventricular nodal level associated with symptoms or hemodynamic compromise, atropine is reasonable to improve atrioventricular conduction,increase ventricular rate, and improve symptoms (Level of Evidence: C-LD[1]
2. For patients with second-degree or thirddegree atrioventricular block associated with symptoms or hemodynamic compromise and who have low likelihood for coronary ischemia, beta-adrenergic agonists, such as isoproterenol, dopamine, dobutamine, or epinephrine, may be considered to improve atrioventricular conduction, increase ventricular rate, and improve symptoms.(Level of Evidence: B-NR)[1] 3.For patients with second-degree or thirddegree atrioventricular block associated with symptoms or hemodynamic compromise in the setting of acute inferior MI, intravenous aminophylline may be considered to improve atrioventricular conduction, increase ventricular rate, and improve symptoms. (Level of Evidence: C-LD)[1] " |
- The acute treatment of bradycardia attributable to atrioventricular block will often begin with timely identification and removal of potential causative factors as well as medical therapy.
Atropine
- Atropine is a parasympatholytic drug that has a short duration of action, is easy to administer and has relatively low risk of adverse reactions (except for obvious antimuscarinic actions).
- It is effect for blocks at the level of the AV node and bradycardia secondary to increased vagal tone. It should be used judiciously in patients with AV blocks at the His-Purkinje or His bundle level as it may worsen the patients condition. [1]
Beta-adrenergic agonists
- Beta-adrenergic agonists such as isoproterenol, dopamine, dobutamine, and epinephrine exert direct effects to enhance atrioventricular nodal and His-Purkinje conduction.
- Adverse effects of beta-adrenergic agonists may include ventricular arrhythmias, excacerbation of coronary ischemia and hypotension. [1]
Amminophylline
- Aminophylline is a nonselective adenosine receptor antagonist and phosphodiesterase inhibitor.
- It is used clinically as a bronchodilator and as a reversal drug for dipyridamole, adenosine, and regadenoson in pharmacologic nuclear stress testing.
- It has a possible role in the treatment of AV block but sparse literature is available regarding this. [1]
Theophylline
- Theophylline is a non-selective adenosine antagonist that may be employed in the treatment of EI-AVB.
- It exerts a positive chronotropic and dromotropic effect.
- A study conducted by Benditt et al showed that theophylline shortened the minimum atrial paced cycle length, maintained 1:1 AV conduction and consistently reduced AV node functional refractory periods. [2]
- In two small observational studies, oral theophylline appeared to be effective over a mean follow-up of 16 and 17 months in patients with an established diagnosis of EI-AVB and may be considered an alternative to permanent pacing in such patients.
- No studies on the role of theophylline in I-AVB are available.
- A few small observational studies on patients with EV-AVB treated with theophylline have recorded a recurrence rate ranging between 12% and 22%.
- In a randomized controlled trial,theophylline proved ineffective in preventing reflex syncope in patients affected by sick sinus syndrome compared with the not treatment arm. "Syncope and paroxysmal atrioventricular block - Aste - 2017 - Journal of Arrhythmia - Wiley Online Library".
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Kusumoto FM, Schoenfeld MH, Barrett C, Edgerton JR, Ellenbogen KA, Gold MR; et al. (2019). "2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: Executive Summary: 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. 74 (7): 932–987. doi:10.1016/j.jacc.2018.10.043. PMID 30412710.
- ↑ Benditt DG, Benson DW, Kreitt J, Dunnigan A, Pritzker MR, Crouse L; et al. (1983). "Electrophysiologic effects of theophylline in young patients with recurrent symptomatic bradyarrhythmias". Am J Cardiol. 52 (10): 1223–9. doi:10.1016/0002-9149(83)90578-7. PMID 6359850.