Paroxysmal AV block electrocardiogram
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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
Electrocardiography is an important initial diagnostic test in diagnosing paroxysmal AV Block. Excercise ECG testing and ambulatory ECG monitoring may be employed.Intrinsic paroxysmal AV block is characterized by atrial premature beats/ventricular premature beats prior to and during the period of asystole. Extrinsic vagal paroxysmal AV block is characterized by sinus rate slowing, increasing PP interval/PR interval prior to the period or asystole. Extrinsic idiopathic paroxysmal AV block is characterized by narrowing of QRS complexes and sinus rate increase prior to the period of asystole.
Electrocardiogram, Holter monitoring, External Loop Recorder
- According to the European Society of Cardiology, indications for ECG monitoring are as follows :
- Immediate in-hospital monitoring (in bed or by telemetry) is indicated in high risk patients.
- Holter monitoring should be considered in patients who have frequent syncope or presyncope (more than or equal to 1 episode per week).
- External loop recorders should be considered, early after the index event, in patients who have an inter symptom interval of less than or equal to 4 weeks. "ESC Guidelines on Syncope (Diagnosis and Management of)".
- The SYNARR- Flash study (Monitoring of SYNcopes and/or sustained palpitations of suspected ARRhythmic origin) was one of the first multicentric observational studies wherein 395 patients with a history of unexplained syncope were monitored with an external ECG device for 4 weeks.
- Based on certain criteria, events were classified as conclusive, significant, suggestive and negative.
- It was found that diagnostic events were seen more in patients in which ECG recordings were initiated within 15 days from the index syncope and those with a history of supraventricular arrhythmias and frequent events. If the patient remained undiagnosed following this 4 week interval, more invasive modalities like implantable loop recorders (ILR) may be considered.[1]
- Brignole et al demonstrated that bundle branch block findings on an ECG does not necessarily correlate to a cardiac related/ bradyarrhythmic syncope.
- Bundle branch block (in particular, a monofasicular block) in a patient with atypical presenting symptoms and advancing age should prompt a physician to think of paroxysmal AV block or a neurally mediated mechanism being behind the syncope. .[2]
2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: Recommendation for Electrocardiogram (ECG)
| Recommendation for Electrocardiogram (ECG) |
| "1. In patients with suspected bradycardia or conduction disorder, a 12-lead ECG is recommended to document rhythm, rate, and conduction, and to screen for structural heart disease or systemic illness..[3](Level of Evidence: B-NR)" |
| Recommendations for Exercise Electrocardiographic Testing |
| "1. In patients with suspected chronotropic incompetence, exercise electrocardiographic testing is reasonable to ascertain the diagnosis and provide information on prognosis. (Level of Evidence: B-NR)[3]
2.In patients with exercise-related symptoms suspicious for bradycardia or conduction disorders, or in patients with 2:1 atrioventricular block of unknown level, exercise electrocardiographic testing is reasonable. (Level of Evidence: C-LD)[3] " |
- Exercise testing can be helpful in distinguishing atrioventricular nodal versus conduction disturbances in the His Purkinje system below the atrioventricular node.
- It is helpful in the diagnosis of chronotropic incompetence or conduction disorders precipitated by myocardial ischemia[3].
| Recommendation for Ambulatory Electrocardiography |
| "1. In the evaluation of patients with documented or suspected bradycardia or conduction disorders, cardiac rhythm monitoring is useful to establish correlation between heart rate or conduction abnormalities with symptoms, with the specific type of cardiac monitor chosen based on the frequency and nature of symptoms, as well as patient preferences(Level of Evidence: B-NR)[3] " |
ECG examples
Classic ECG Findings seen in the different types of paroxysmal AV Block are as follows :
References
- ↑ Locati ET, Moya A, Oliveira M, Tanner H, Willems R, Lunati M; et al. (2016). "External prolonged electrocardiogram monitoring in unexplained syncope and palpitations: results of the SYNARR-Flash study". Europace. 18 (8): 1265–72. doi:10.1093/europace/euv311. PMC 4974630. PMID 26519025.
- ↑ Donateo P, Brignole M, Alboni P, Menozzi C, Raviele A, Del Rosso A; et al. (2002). "A standardized conventional evaluation of the mechanism of syncope in patients with bundle branch block". Europace. 4 (4): 357–60. doi:10.1053/eupc.2002.0265. PMID 12408253.
- ↑ 3.0 3.1 3.2 3.3 3.4 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.