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A3444 - Can Trauma Cause Water to Flow Upstream?
Author Block: J. Sahbaz, A. Zviman, G. Ramani; University of Maryland School of Medicine, Baltimore, MD, United States.
Introduction: Platypnea-orthodeoxia (P-O) syndrome is a rare but often under-diagnosed condition in which transition from recumbency to standing produces hypoxia, and occasionally dyspnea. The symptomatology is a result of an existing inter-atrial communication and a functional abnormality that produces a right-to-left pressure gradient upon positional changes. Below, we describe a case of P-O syndrome diagnosed years after a motor vehicle accident (MVA). Case: A 38-year-old athletic woman with a history of migraine headaches presented with dizziness and dyspnea while performing pushups and bending exercises. She checked her oxygen saturations during exercise and these were occasionally between 80-85 %. She was involved in an MVA 2 years earlier. Initial diagnostic evaluation, including CTA of the chest, CPEX, and PFT, and transthoracic echocardiogram (TTE) were normal. Laboratory studies were all unremarkable. In light of the intermittent hypoxia, a high flow oxygen shunt study was performed, demonstrating a post-oxygenation PaCO2 of 22 mmHg and PaO2 of 377 mmHg; thus, yielding a Qs/Qt shunt fraction of 16.0% consistent with a significant right-to-left shunt. TTE with agitated saline showed an EF of 60%, normal right ventricular size, and a small right-to-left shunt. Subsequent exercise right heart catheterization demonstrated normal filling pressures with normal cardiac output and an appropriate augmentation during exercise. Agitated saline TTE was performed in the catheterization lab during exercise. Nominal right-to-left shunting was noted while supine, but oxygen saturations remained at 99 % However, when she sat up, a large right-to-left shunt was observed with agitated saline injection with significant oxygen desaturation. Transesophageal echocardiography revealed a small patent foramen ovale (PFO) with normal biventricular function and valvular function. She underwent successful closure of her PFO using a percutaneous occluder device. Postoperative TTE demonstrated no residual evidence of intra-cardiac shunting, and she returned to strenuous exercise within 2 months without hypoxia or dyspnea. Discussion: P-O syndrome was first described in the late 1940s, and has since been identified in several pathologic etiologies. Over 188 case reports have been published describing this rare and interesting phenomenon. The case described above represents the third recognized case of P-O syndrome after blunt chest wall injury, with 2 of the 3 cases resulting after high-speed MVA. As compared to other reported cases, this case is unique in that trauma from the accident either served to increase blood flow through an underlying inter-atrial shunt or, less likely, create a de-novo atrial communication.