A Rare Presentation of Central Airway Obstruction and Cardiac Arrest Secondary to Megaesophagus From Superior Mesenteric Artery Syndrome

Abstract

Introduction: Superior mesenteric artery syndrome (SMAS) is a rare clinical entity characterized by compression of the third or transverse portion of the duodenum between the aorta and the SMA. Patients can present with dyspepsia, postprandial discomfort or vomiting as a result of recurrent, acute or chronic duodenal obstruction. CASE PRESENTATION: A 53-year-old man with a history of dysphagia and 25 pound weight loss presented to the emergency room due to postprandial, witnessed cardiac arrest. The initial rhythm was pulseless electrical activity (PEA) and return of spontaneous circulation was achieved after 36 minutes. Physical exam revealed an unresponsive cachectic man and chest auscultation revealed diminished breath sounds on the right. Computed tomography of the chest revealed a dilated esophagus occupying the majority of the right hemithorax and superior mediastinum, causing mass effect on central airways, aortic arch and right brachiocephalic vessels (image 1). There was marked dilatation of the stomach down to the third portion of the duodenum. The transition zone occurred distal to the third segment of duodenum between the aorta and superior mesenteric artery, consistent with SMAS. Endoscopy excluded endoluminal obstruction. To our knowledge, this is the first case of megaesophagus from SMAS presenting as PEA arrest from tracheal mass effect. DISCUSSION: SMAS occurs due to narrowing of the aortomesenteric (AOM) angle to < 25degree and AOM distance <8mm, causing entrapment and compression of the third part of the duodenum as it passes between the SMA and aorta. The normal AOM angle is between 45degree and 60degree and the normal AOM distance is between 10 mm and 20 mm. Potential etiologic factors include anorexia, depletion of mesenteric fat, spinal deformities, and scoliosis surgery. Nasogastric decompression, correction of electrolyte imbalance and nasojeunal tube feeding serve as initial stabilizing measure. Duodenojejunostomy is the definitive treatment. Other presentations include pneumoperitoneum and pneumomediastinum; as well as nutcracker phenomenon, described as microscopic hematuria and left sided varicocele due to compression of the left renal vein. Conclusions: SMAS should be in the differential diagnosis of patients presenting with weight loss, high intestinal obstruction and typical transition point. Acute respiratory failure and cardiac arrest can occur as a result of mass effect.