Initial Single-Center Experience With the Knickerbocker Technique During Thoracic Endovascular Aortic Repair to Block Retrograde False Lumen Flow in Patients With Type B Aortic Dissection

Abstract

Objective: Effectiveness of thoracic endovascular aortic repair in type B aortic dissection is impaired by persistent retrograde false lumen flow via distal re-entry tears. Controlled, stentgraft-assisted balloon dilatation of the true lumen at its lower end, or Knickerbocker technique, may block retrograde false lumen flow and consequently improve effectiveness by inducing immediate thrombosis along the entire descending thoracic aorta. Materials and Methods: A single-center retrospective analysis was performed for all consecutive patients with aortic dissection treated with the Knickerbocker technique to block retrograde false lumen flow. Results: Eleven patients were included for analysis. Intraoperative control angiography showed successful occlusion of the false lumen at the level of balloon dilatation in 9 out of 11 patients (82%). There was one perioperative mortality (9%), due to stroke. There were 2 early reinterventions, due to retroperitoneal bleeding and due to chyle leakage in the neck after left subclavian artery bypass. Median clinical follow-up duration was 6 (interquartile range [IQR] 2–11] months. There were 2 deaths during follow-up, one at 2 months after TEVAR from unknown cause of death, and one after 11 months due to rupture of an ascending aortic pseudoaneurysm. The Knickerbocker technique led to positive aortic remodeling. At 3 months follow-up, 100% of patients showed complete false lumen thrombosis in the thoracic aorta proximal to the level of balloon dilatation, with decreasing false lumen diameters (100%) and stable (44%) or decreasing (56%) total aortic diameters. In most patients, the false lumen distal to the stentgraft (i.e. at visceral level) remained patent (11% false lumen thrombosis rate), leading to ≥2 mm dilatation at this level (78% of patients) and in the infrarenal abdominal aorta (56% of patients) at 3 months postoperatively. No distal stent-graft-induced new entry tears were noticed during follow-up. Conclusion: The Knickerbocker technique is feasible and effective, leading to positive aortic remodeling of the aorta covered by stentgraft in all of a small cohort of patients. Clinical Impact Persistent, retrograde false lumen perfusion from distal re-entries following thoracic endovascular aortic repair (TEVAR) for Stanford type B aortic dissection, may lead to progressive, aneurysmal dilatation. Controlled, stent graft-assisted balloon dilatation of the true lumen in the distal descending aorta (i.e. Knickerbocker technique) during TEVAR effectively excludes the false lumen from persistent flow resulting in positive aortic remodeling in our small cohort of patients, and hence potentially eliminates the risk of late post-dissection aneurysm formation in the descending thoracic aorta.