# An Unusual Case of Paroxysmal Third-Degree Atrioventricular Block: Thinking Outside the Box

## TL;DR

This paper presents a rare case of third-degree heart block caused by bladder issues and eye drops, highlighting the need for broader diagnostic thinking.

## Contribution

The paper highlights an unusual combination of bladder outlet obstruction and ophthalmic beta-blocker use as a cause of third-degree AV block.

## Key findings

- An 80-year-old male presented with symptomatic extrinsic vagal AV block.
- Bladder outlet obstruction and chronic ophthalmic beta-blocker use were identified as likely causes.
- These factors are often overlooked in diagnosing third-degree AV block.

## Abstract

During the assessment of a third-degree atrioventricular (AV) block in a patient with syncope, different etiologies should be considered and evaluated. Extrinsic vagal paroxysmal AV block, extrinsic idiopathic AV block and intrinsic paroxysmal AV block are among the types of third-degree AV block in the differential diagnoses. Extrinsic vagal paroxysmal third-degree atrioventricular block (EV-AVB) is linked to parasympathetic influence on cardiac conduction and can be observed in bladder distention and urinary retention. Topical and ophthalmic beta-blockers have shown systemic effects such as bradycardia with and without syncope. We present the case of an 80-year-old male with symptomatic EV-AVB likely precipitated by bladder outlet obstruction and chronic use of an ophthalmic beta-blocker, often overlooked causes of third-degree AV block.