Second degree AV block natural history, complications and prognosis
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Raviteja Guddeti, M.B.B.S. [2]
Overview
Patients with Mobitz type II second degree AV block who are hemodynamically stable do not require urgent therapy with atropine or temporary cardiac pacing. However, Mobitz type II second degree AV block is by nature unstable and frequently progresses to third degree (complete) AV block, so patients should be continuously monitored with transcutaneous pacing pads in place in the event of clinical deterioration. While stable patients are being monitored, reversible causes of Mobitz type II second degree AV block such as myocardial ischemia, increased vagal tone, hypothyroidism, hyperkalemia, and drugs that depress conduction, should be excluded in patients prior to implantation of a permanent pacemaker. For patients with Mobitz type II second degree AV block who do not have a reversible etiology, we recommend implantation of a permanent pacemaker (Grade 1A). We implant a dual chamber DDD pacemaker whenever possible in an effort to maintain physiologic AV synchrony.
Natural History
- Mobitz I second degree AV block, usually most of the times, involves the AV node (70%). In about 30% of the cases the site of block is infranodal. It is usually benign and rarely progresses to complete heart block[1].
- Mobitz II second degree Av block is due to block inferior to the AV node (infra-Hisian structures) and it progresses to complete heart block[2].
Complications
Prognosis
Mobitz type I second degree AV block is usually benign and carries a good prognosis compared to Mobitz type II. But in the setting of an acute MI Mobitz type I is associated with a significant rise in mortality. Mobitz II, as it involves the infra nodal structures, carries the risk of progression to complete heart block and carries an unfavorable prognosis.[4]
References
- ↑ Strasberg B, Amat-Y-Leon F, Dhingra RC, Palileo E, Swiryn S, Bauernfeind R, Wyndham C, Rosen KM (May 1981). "Natural history of chronic second-degree atrioventricular nodal block". Circulation. 63 (5): 1043–9. doi:10.1161/01.cir.63.5.1043. PMID 7471363.
- ↑ Rodstein M, Wolloch L, Iuster Z (1979). "The natural history intraventricular conduction disturbances in the aged: an analysis of the developing second and third degree heart block with clinical pathological correlations". Am. J. Med. Sci. 277 (2): 179–88. doi:10.1097/00000441-197903000-00006. PMID 463945.
- ↑ Bexton RS, Camm AJ (March 1984). "Second degree atrioventricular block". Eur. Heart J. 5 Suppl A: 111–4. doi:10.1093/eurheartj/5.suppl_a.111. PMID 6373268.
- ↑ Meimoun P, Zeghdi R, D'Attelis N, Berrebi A, Braunberger E, Deloche A; et al. (2002). "Frequency, predictors, and consequences of atrioventricular block after mitral valve repair". Am J Cardiol. 89 (9): 1062–6. doi:10.1016/s0002-9149(02)02276-2. PMID 11988196.