An asymptomatic case of type B dissection developing type A dissection during transferRunning title: Asymptomatic retrograde type A aortic dissectionKayo Sugiyama1, Hirotaka Watanuki1, Masato Tochii1, Katsuhiko Matsuyama11Department of Cardiac Surgery, Aichi Medical University Hospital, 1-1 Yazako Karimata, Nagakute, Aichi, 480-1195, JapanCorresponding author: Kayo Sugiyama, MD, PhDDepartment of Cardiac Surgery, Aichi Medical University Hospital, 1-1 Yazako Karimata, Nagakute, Aichi, 480-1195, JapanTel: +81-561-62-3311, Fax: +81-561-63-6193E-mail: [email protected]

Background: Mesenteric malperfusion is a complication with a higher risk of in-hospital mortality because diagnosing mesenteric ischemia before necrotic change is difficult, and when it occurs, the patient’s condition has worsened. Although it contradicts the previous consensus on central repair-first strategy, the revascularization-first strategy was found to be significantly associated with lower mortality rates. The aim of this study is to present our revascularization-first strategy and assess the postoperative results for acute aortic dissection involving mesenteric malperfusion. Methods: Among 58 patients with acute type A aortic dissection at our hospital between January 2017 and December 2019, mesenteric malperfusion was noted in six. Four hemodynamically stable patients underwent mesenteric revascularization with endovascular intervention in a hybrid operation room before central repair, and two hemodynamically unstable patients underwent central repair before mesenteric revascularization. Results: No in-hospital mortality was recorded. All four patients with mesenteric revascularization-first strategy recovered with no symptoms related to mesenteric ischemia. Two patients with central repair-first strategy developed paralytic ileus for 1 week; one of them needed explorative laparotomy, but no patients needed colon resection. Conclusion: The revascularization-first strategy in cases of acute type A aortic dissection with mesenteric malperfusion may achieve favorable results. However, in cases with other-major organ malperfusion or having hemodynamically unstable status, the appropriate strategy is controversial. Close evaluation of mesenteric perfusion using multiple modalities and prompt revascularization are mandatory in these complicated cases. A hybrid operation room provides an ideal environment for this revascularization-first strategy.

Few studies have reported re-sternotomy after an omental flap procedure. We describe the case of a 78-year-old man who received re-sternotomy after omental flap procedure for deep sternal wound infection and successfully underwent coronary artery bypass grafting. Although preoperative computed tomography showed funnel chest and limited space between the sternum and omentum, re-sternotomy was performed safely using circular electric sternum saw under partial cardiopulmonary bypass. Because the omentum functioned as cushioning material between the sternum and mediastinal organs, no injuries of the mediastinal organs occurred. An ultrasonic scalpel effectively dissected between the omentum and mediastinal organs, especially above the ascending aorta. The targeted coronary arteries were easily detected. The patient experienced no major cardiac or infectious events for three months. An ultrasonic scalpel is recommended for dissecting between the omentum and mediastinal organs.