SHM Converge Scientific Abstract ePoster Gallery-Infective Endocarditis of the Mitral Valve Complicated by Platypnea-Orthodeoxia Syndrome in an Adult With Atrial Septal Defect and Bidirectional Shunting

Infective Endocarditis of the Mitral Valve Complicated by Platypnea-Orthodeoxia Syndrome in an Adult With Atrial Septal Defect and Bidirectional Shunting

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This case report describes a 48-year-old man with an untreated atrial septal defect (ASD) who developed methicillin-susceptible <em>Staphylococcus aureus</em> (MSSA) bacteremia and infective endocarditis (IE) of the mitral valve. He presented with fever, severe pain and impaired movement, and signs of systemic infection. Blood tests showed marked inflammation, and blood cultures grew MSSA. Imaging revealed a mitral valve vegetation, multiple cerebral infarctions, splenic infarction, right renal infarction, and nodular/cavitating lesions in both lungs, indicating septic emboli affecting both systemic and pulmonary circulations.

Transesophageal echocardiography and right heart catheterization demonstrated an ASD with bidirectional shunting. During hospitalization, the patient developed position-dependent oxygen desaturation, leading to a diagnosis of platypnea–orthodeoxia syndrome (POS). The authors concluded that the ASD and mitral valve damage from IE likely contributed to abnormal shunt physiology and hypoxemia.

The case highlights several important points: although ASD has traditionally not been considered a major risk factor for IE, more recent evidence suggests adults with ASD may have a higher risk than the general population. In this patient, the untreated ASD may have facilitated the complex hemodynamics and paradoxical distribution of septic emboli. The report emphasizes that IE should be suspected in patients with ASD who present with fever, embolic phenomena, or unexplained oxygen desaturation, especially when symptoms vary with posture.

Asset Subtitle

Naomitsu Akimoto

Meta Tag

Author List Daisuke Haratake, Daisuke Miyamori, Kana Sakai, Keishi Kanno, Kotaro Ikeda, Masanori Ito, Naomitsu Akimoto, Sachi Nagasaka, Shuhei Yoshida, Yuya Shigenobu

Category Clinical Vignettes

Concept Infective Endocarditis

Concept Atrial Septal Defect

Concept Platypnea-Orthodeoxia Syndrome

Concept Septic Emboli

Concept Blood Culture

Distinguished Non-Finalist

Presenter Organization Hiroshima University Hospital

Presenting Author Naomitsu Akimoto

Track Adult

Keywords

atrial septal defect

infective endocarditis

Staphylococcus aureus

bacteremia

mitral valve vegetation

septic emboli

platypnea-orthodeoxia syndrome

bidirectional shunt

systemic infarction

pulmonary embolic lesions

Infective Endocarditis

Atrial Septal Defect

Platypnea-Orthodeoxia Syndrome

Septic Emboli

Blood Culture