An unusual cause of exercise dyspnoea and hypoxia after cardiac surgery: a case report.

Background: Dyspnoea is a cardinal clinical feature of post-cardiac surgery patients and represents one of the most significant postoperative complications, whether of cardiac or pulmonary origin. Case summary: We report the case of a 52-year-old woman with mitral valve prolapse with severe regurgitation and a moderate-to-severe tricuspid regurgitation, who underwent mitral and tricuspid valvuloplasty using the Guiraudon approach. In the late postoperative phase, during cardiac rehabilitation, the patient experienced dyspnoea during low-intensity exercise associated with significant oxygen desaturation. A surgical technique-guided transthoracic echocardiography revealed a large atrial septal suture dehiscence (ASSD) with a significant bidirectional shunt, which was confirmed by transoesophageal echocardiography. An expert-performed cardiopulmonary exercise testing confirmed the pathophysiological link between ASSD and oxyhaemoglobin desaturation during effort. The patient subsequently underwent a second cardiac surgery to repair the ASSD, which led to the resolution of symptoms and a significant improvement in functional capacity, without further oxygen desaturation. Discussion: This case underscores the importance of a multiparametric diagnostic approach and integrating expert-performed imaging and surgical technique-guided assessments in addressing the common challenge of post-cardiac surgery dyspnoea. The cardiac rehabilitation setting provides an ideal multidisciplinary environment for early detection and effective management of such complications.