Paroxysmal AV block Treatment for Reflex Syncope

• Once a diagnosis of EV-AVB has been made, the following guidelines may be helpful ;

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

Counter Pressure Maneuvers-"ESC Guidelines on Syncope (Diagnosis and Management of)".

2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay

• Vagally mediated atrioventricular block observed with ambulatory electrocardiographic monitoring may be an incidental finding that occurred while the patient was sleeping or in other cases be associated with syncope.
• Vagally mediated atrioventricular block is felt to be attributable to neural reflexes, which result in simultaneous bradycardia and hypotension.
• There is typically sinus rate slowing in conjunction with the onset of atrioventricular block and the atrioventricular block can be high grade or complete.
• Atrioventricular block attributable to high vagal tone, such as during sleep, is almost always asymptomatic.
• The level of the block is at the atrioventricular node, and there is normal atrioventricular nodal function when tested at EPS.
• If asymptomatic, medical treatment or pacemaker implantation is not warranted for atrioventricular block attributable to high vagal tone or vagally mediated atrioventricular block.
• If the patient is having frequent syncopal episodes, treatment may be warranted if bradycardia appears to be the dominant factor in these episodes.
• Although PPM implantation is a relatively low-risk cardiac procedure, procedural complications and death directly related to implant can occur, and implanted leads have long-term management implications.

Atropine and Isoproterenol

• Atropine shortens the refractoriness of the atrioventricular node but has little effect on infranodal conduction tissues.
• Atropine will improve or have no change in atrioventricular conduction block if the block is at the level of the atrioventricular node but will worsen atrioventricular conduction block in the presence of intra-His or distal conduction disease.
• Isoproterenol can also be used to unmask underlying pathologic His-Purkinje disease by enhancing atrioventricular nodal and sinus conduction and precipitating heart block with faster heart rates.
• Similar to atropine, worsening atrioventricular block with isoproterenol infusion would be suggestive of infranodal block.