Paroxysmal AV block
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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]
Synonyms and keywords:
Overview
Historical Perspective
- There is limited information about the historical perspective of paroxysmal AV block.
- In 1931, Adolph Sachs et al reported one of the first cases on paroxysmal AV block. The patient had presented with multiple spells of palpitations, hot flashes, dizziness, ringing in the ears, weakness and diaphoresis accompanied by convulsions. During an acute episode, he noticed an irregular ventricular rhythm, irregular complexes and given a time interval of 30 seconds, the ventricle would beat once in the first 15 second window and 4-5 times in the succeeding window. It was noticed that the duration of the block progressively increased until it was present all the time. Mitral valvulitis was put down as the cause of the attack and the fact that a response to atropine does not rule out an intrinsic conduction defect was emphasized. [1]
- In 1972, Philippe Coumel et al hypothesized that the cause of bradycardia/pause dependent AV block was the spontaneous depolarization of specialized conducting fibers in the late stages of diastole. It was during this ‘zone of opportunity’ that they noticed this ‘AV dissociation’. In this case, they found that the block occurred to be proximal to the division of the His bundle. [2]
- In 1997. Brignole et al first described EI AVB in a group of 15 syncope patients with an initial negative work up. They fortuitously stumbled upon ECG findings indicating a paroxysmal AV block and reconfirmed this by performing an adenosine triphosphate test in each patient. [3]
Classification
- Paroxysmal AV Block may be classified according to the cause into three types :
- Intrinsic AV Block (I-AVB)
- Extrinsic Vagal AV Block (EV- AVB)
- Extrinsic Idiopathic AV Block (EI- AVB)[4]
| Paroxysmal AV Block classification based on cause | |||||||||||||||||||||||||||||||||||
| Intrinsic AV Block (I-AVB): Due to innate structural/ conduction defect | Extrinsic Vagal AV Block (EV- AVB): Due to vagal surge/reflex | Extrinsic Idiopathic AV Block (EI- AVB) : Due to innately low adenosine plasma levels | |||||||||||||||||||||||||||||||||
| Tachycardia Dependent AV Block (TD- AVB) | Bradcardia/Pause Dependent AV Block (BD- AVB/PD-AVB) | ||||||||||||||||||||||||||||||||||
Pathophysiology
Causes
Differentiating Paroxysmal AV block from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
Diagnostic study of choice | History and Symptoms | Physical Examination | Laboratory Findings | Electrocardiogram | X-Ray Findings | Echocardiography and Ultrasound | CT-Scan Findings | MRI Findings | Other Imaging Findings | Other Diagnostic Studies
Treatment
Medical Therapy | Interventions | Surgery | Primary Prevention | Secondary Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies
Case Studies
- ↑ "Paroxysmal complete auriculo-ventricular heart-block: A case report - ScienceDirect".
- ↑ "Bradycardia-dependent atrio-ventricular block: Report of two cases of A-V block elicited by premature beats - ScienceDirect".
- ↑ Brignole M, Gaggioli G, Menozzi C, Gianfranchi L, Bartoletti A, Bottoni N, Lolli G, Oddone D, Del Rosso A, Pellinghelli G (December 1997). "Adenosine-induced atrioventricular block in patients with unexplained syncope: the diagnostic value of ATP testing". Circulation. 96 (11): 3921–7. doi:10.1161/01.cir.96.11.3921. PMID 9403616.
- ↑ 4.0 4.1 Aste M, Brignole M (December 2017). "Syncope and paroxysmal atrioventricular block". J Arrhythm. 33 (6): 562–567. doi:10.1016/j.joa.2017.03.008. PMID 29255501.