Paroxysmal AV block differential diagnosis

link=https://www.wikidoc.org/index.php/Paroxysmal AV block

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Akash Daswaney, M.B.B.S[2]

Overview

Considering that a number of conditions may present with a history of syncope and presyncope, paroxysmal AV block must treated as a diagnosis of exclusion. Vasaovagal syncope, situational syncope, carotid sinus hypersensitivity, seizures, structural heart defects such as aortic stenosis, hypertrophic cardiomyopathy and conduction defects such as atrial fibrillation, atrial flutter are a few conditions that need to be ruled out initially.

Differential Diagnosis

Disease	Findings
Vasaovagal Syncope	Occurs secondary to emotional distress, prolonged standing, painful stimuli. Seen more in women and may be diagnosed by tilt table testing. Not associated with periods of asystole.
Situational Syncope	Due to cardioinhibitory and vasopressor mechanisms. Syncope may be associated with cough, micturition and defecation. Not associated with periods of asystole.
Carotid Sinus hypersensitivity	Common causes of unexplained syncope in individuals more than 40 years of age. Syncope may be associated with wearing shirts with tight collars. Not associated with periods of asystole.
Aortic Stenosis	Presents with syncope, angina and dyspnea on exertion. Not associated with periods of asystole but may show features of left ventricular hypertrophy. On Physical examination,pulsus parvus et tardus may be noted and a systolic click followed by a crescendo decrescendo murmur may be heard over the aortic area.
Hypertrophic Cardiomyopathy	Common cause of sudden cardiac death in adolescents during physical activity. Family history is often present. Not associated with periods of asystole.
1st Degree AV Block	P waves associated with 1:1 atrioventricular conduction and a PR interval >200 ms (this is more accurately defined as atrioventricular delay because no P waves are blocked)
2nd Degree AV Block	P waves with a constant rate (<100 bpm) where atrioventricular conduction is present but not 1:1. Mobitz Type 1: P waves with a constant rate (<100 bpm) with a periodic single nonconducted P wave associated with P waves before and after the nonconducted P wave with inconstant PR intervals. Mobitz Type 2 : P waves with a constant rate (< 100 bpm) with a periodic single nonconducted P wave associated with other P waves before and after the nonconducted P wave with constant PR intervals (excluding 2:1 atrioventricular block)
3rd Degree AV Block	No evidence of atrioventricular conduction.
Atrial Fibrillation	May present with syncope, presyncope, lightheadedness or palpitations. Associated with irregular RR intervals and absence of clearly defined P waves.
Congenital long QT syndrome/ Torsade de pointes	Associated with electrolyte abnormalities such as hypokalemia, hypomagnesemia, hypocalcemia or congenital conditions such as Jervell- Lange- Nielsen Syndrome and Romano Ward Syndrome which may degenerate into a life threatening polymorphic ventricular tachycardia.
Seizures	May be associated with generalized tonic clonic movements, tongue bite, bowel or bladder incontinence, a post ictal state and Todd’s paralysis. Following a loss of consciousness, there is a delayed recovery time.
Others	Atrial Flutter,Subclavian Steal syndrome, Vertebrobasilar Transient Ischemic Attacks, Sick Sinus Syndrome, Psychogenic Pseudosyncope, Psychogenic Non epileptic Seizures.

"ESC Guidelines on Syncope (Diagnosis and Management of)".

References

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