Case Summary
We report a 64yo male with a history of severe aortic stenosis who underwent aortic valve replacement in 2015 with a 21 mm Mitroflow bioprosthetic valve (Sorin, Arvada, CO) at an outside hospital. The postoperative course was complicated by pan-sensitive Serratia Marcescens deep sternal wound infection and mediastinitis requiring multiple debridements and treatment with a six-week course of intravenous vancomycin and ceftriaxone. He subsequently required a sternal reconstruction using bilateral pectoralis major flaps and a right rectus abdominis flap. He acutely did well from this hospitalization. However, he then presented three months after his index surgery with 2-3 day history of fevers, chills, and a new sternal mass. His surgeon considered acutely decompressing the mass at the bedside but decided to transfer the patient to our institution.
Upon arrival at our institution he was neurologically intact with an EKG showing sinus tachycardia, all other vitals within normal limits. His exam was impressive with a rapidly enlarging, erythematous, anterior chest wall mass (Figure 1, 2 ). An urgent computed tomographic angiogram (CTA) scan of the chest demonstrated a blush at the aortic cannulation site with active arterial extravasation into a massive pseudoaneurysm of the distal ascending aorta filling the entire anterior mediastinum (Figure 3 ). Echocardiogram demonstrated grossly normal left ventricle (LV) systolic function with poor visualization of the ascending aorta. Percutaneous coverage of the pseudoaneurysm as a temporizing measure was considered but not feasible due to a lack of distal landing zone or a small enough neck.
Given the rapid expansion, he was taken emergently to the operating room for repair. The right femoral vein and artery were cannulated and patient was cooled. Due to several small aortic paravalular leaks and concern for LV distension, a left anterior thoracotomy was performed and an LV vent placed directly through the LV apex. Manual compression was also required to keep the LV from distending.
By the time the patient’s temperature reached 28ºC with the LV continuing to distend, a redo sternotomy was performed. Upon entering the anterior mediastinum, the large pseudoaneurysm was grossly entered with evidence if acute arterial hemorrhage. Circulatory arrest was initiated and the aorta was rapidly dissected out to identify the aortic cannulation site where multiple, pledgeted sutures were identified loosely attached at the original cannulation site. A cowhorn dilator was placed in the defect to control the aorta and cardiopulmonary bypass (CPB) was re-initiated.
Now with some control of the aorta, a sternal retractor was placed and the aorta was dissected circumferentially. Under a second duration of hypothermic circulatory arrest. A large, bovine pericardial patch was then sewn in running fashion around the defect. This appeared to achieve hemostasis at the defect site and the patient was rewarmed and weaned off of CPB without difficulty. The right groin and left anterior thoracotomy were closed in standard fashion.
The decision was made to pack the chest due to mild coagulopathy and prior complex closure. The patient remained intubated, sedated, and on vasopressors for the duration of the postoperative period. Total time on cardiopulmonary bypass was 171 minutes, with 24 minutes (6 minutes on entry, and 18 minutes while sewing patch) of total hypothermic circulatory arrest time.
His postoperative course was complicated by seizures thought to be due to air embolism on subsequent MRI. His operative wound cultures grewCandida albicans . Although he underwent successful washout and closure of his flaps, he later become profoundly hypotensive with acute hemorrhage from his chest tubes. Upon emergently opening his chest, 3 liters of blood was noted in his mediastinum with bleeding from the left side of the bovine pericardial patch. The aorta quality was poor. Hemostasis was achieved with primary repair. Temporary closure was performed and the chest was packed. The patient was weaned off pressors. Ultimately, given the complex disease and concerning neurological status, the decision was made to transition to comfort care and the patient expired soon after.