Cardiac surgeon The University Of Western Ontario Western University London, Ontario, Canada
Background: Malperfusion carries the highest risk of morbidity and mortality in acute type A aortic dissections(ATAAD). Several international centers have developed specialized protocols to diagnose/treat malperfusion in ATAAD. However they are very resource intense limiting their usefulness at other institutions. Intravascular ultrasound(IVUS) is readily available at most centers. Here we evaluate the effectiveness of IVUS for intraoperative assessment of malperfusion during ATAAD repair.
METHODS AND RESULTS: 50 consecutive patients, presenting with acute TAAD, were split into 3 groups. 1-those presenting with evidence of malperfusion, 2-those without any evidence of malperfusion and 3-those who developed evidence of malperfusion intraoperatively following proximal aortic repair. After cross-clamp removal, all patients underwent IVUS evaluation of the aorta from the aortic arch to the femoral arteries. All aortic branches were evaluated by; identifying true/false lumen origin, the expansion or collapse of the lumens at each level, the presence of any clot, the location and mobility of the dissection flap and any other features concerning for arterial obstruction or malperfusion. Patients were then followed clinically, with bloodwork done on post-operative day 1,7 and 30, or the date of discharge. Primary outcomes were a composite of all-cause hospital mortality, acute kidney injury requiring new permanent hemodialysis, mesenteric ischemia or vascular complication requiring intervention.
To date, 44/50 patients have been successfully enrolled, with completion of the study expected in the next few months. 28.6% of patients (12/44) presented with clinical evidence of malperfusion(Group 1). 71.4% (32/44) did not present with any evidence of malperfusion(Group 2). No patients developed malperfusion intraoperatively(Group 3). IVUS identified malperfusion in 41.7% (5/12) of Group 1 patients intraoperatively, prompting early intervention in 4 of these cases. Intervention included extension TEVAR and aortic stenting, endovascular peripheral arterial stenting, and septal fenestration. Our primary endpoint was reached in 18.2%(8/44) of patients with seven post-operative deaths (15.9%) and one patient that required a thrombin injection for a 1x2cm pseudoaneurysm at the femoral artery puncture site on the day of discharge (2.3%). Following intraoperative IVUS evaluation and treatment of malperfusion, we did not observe a single case of acute kidney injury requiring permanent dialysis or mesenteric ischemia requiring any intervention.
Conclusion: IVUS evaluation in ATAAD has shown to be a readily available, safe and effective technique for immediate diagnosis of malperfusion. This technique allows for early intervention and a drastic reduction in peri-operative complications. A multicenter RCT is warranted to evaluate intraoperative IVUS assessment as a standard of care in ATAAD repair.
