# Platypnea-Orthodeoxia Syndrome Revealing an Undiagnosed Patent Foramen Ovale: A Case Report

## TL;DR

A 76-year-old woman's breathing issues were traced to a heart defect called patent foramen ovale, which was successfully treated with a minimally invasive procedure.

## Contribution

This case report highlights a rare delayed diagnosis of POS due to PFO despite prior thromboembolic events.

## Key findings

- Transesophageal echocardiography confirmed a PFO as the cause of POS in the patient.
- Percutaneous closure of the PFO resolved the patient's symptoms completely.
- The case emphasizes the importance of considering PFO in undiagnosed cases of POS.

## Abstract

Platypnea-orthodeoxia syndrome (POS) is an uncommon clinical entity characterized by position-dependent hypoxemia that worsens when standing and improves when lying down. Patent foramen ovale (PFO) was the most commonly reported site of an intracardiac shunt. In addition to PFO, intracardiac shunt leading to POS has been reported from either an atrial septal defect (ASD) or an atrial septal aneurysm (ASA). In cases where POS occurs due to intracardiac shunting in the absence of pulmonary hypertension, closure of the defect can be curative.

We report a rare case of POS caused by a PFO in a 76-year-old woman. Transesophageal echocardiography was essential for identifying the shunt, excluding the presence of pulmonary hypertension, enabling successful percutaneous closure and complete resolution of her symptoms. This case adds novelty beyond typical PFO-related POS due to delayed diagnosis despite prior thromboembolic events.