Endovascular versus open surgical repair for complicated chronic Type B aortic dissection.

BACKGROUND: Type B aortic dissection can lead to serious and life-threatening complications such as aortic rupture, stroke, renal failure, and paraplegia, all of which require intervention. Traditionally, these complications have been treated with open surgery. Recently however, endovascular repair has been proposed as an alternative. OBJECTIVES: To assess the effectiveness and safety of thoracic aortic endovascular repair versus open surgical repair for treatment of complicated chronic Type B aortic dissection (CBAD). SEARCH METHODS: The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, and AMED databases, as well as the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers, to 2 August 2021. We searched references of relevant articles retrieved through the electronic search for additional citations. SELECTION CRITERIA: We considered all randomised controlled trials (RCTs) and controlled clinical trials (CCTs) assessing the effects of thoracic aortic endovascular repair (TEVAR) versus open surgical repair (OSR) for treatment of complicated chronic Type B aortic dissection (CBAD). Outcomes of interest were mortality (all-cause, dissection-related), neurological sequelae (stroke, spinal cord ischaemia/paresis-paralysis, vertebral insufficiency), morphological outcomes (false lumen thrombosis, progression of dissection, aortic diameters), acute renal failure, ischaemic symptoms (visceral ischaemia, limb ischaemia), re-intervention, and health-related quality of life. DATA COLLECTION AND ANALYSIS: Two review authors independently screened all titles and abstracts identified by the searches to identify those that met the inclusion criteria. From title and abstract screening, we did not identify any trials (RCTs or CCTs) that required full-text assessment. We planned to undertake data collection and analysis in accordance with recommendations described in the Cochrane Handbook for Systematic Reviews of Interventions. We planned to assess the certainty of evidence using GRADE. MAIN RESULTS: We did not identify any trials (RCTs or CCTs) that met the inclusion criteria for this review. AUTHORS' CONCLUSIONS: Due to lack of RCTs or CCTs investigating the effectiveness and safety of TEVAR compared to OSR for patients with complicated CBAD, we are unable to provide any evidence to inform decision-making on the optimal intervention for these patients. High-quality RCTs or CCTs addressing this objective are necessary. However, conducting such studies will be challenging for this life-threatening disease.

Development of a test method to investigate mode II fracture and dissection of arteries.

The current study presents the development and implementation of a bespoke experimental technique to generate and characterise mode II crack initiation and propagation in arterial tissue. The current study begins with a demonstration that lap-shear testing of arterial tissue results in mixed mode fracture, rather than mode II. We perform a detailed computational design of a bespoke experimental method (which we refer to as a shear fracture ring test (SFRT)) to robustly and repeatably generate mode II crack initiation and propagation in arteries. This method is based on generating a localised region of high shear adjacent to a cylindrical loading bar. Placement of a radial notch in this region of high shear stress is predicted to result in a kinking of the crack during a mode II initiation and propagation of the crack over a long distance in the circumferential (c)-direction along the circumferential-axial (c-a) plane. Fabrication and experimental implementation of the SFRT on excised ovine aorta specimens confirms that the bespoke test method results in pure mode II initiation and propagation. We demonstrate that the mode II fracture strength along the c-a plane is eight times higher than the corresponding mode I strength determined from a standard peel test. We also calibrate the mode II fracture energy based on our measurement of crack propagation rates. The mechanisms of fracture uncovered in the current study, along with our quantification of mode II fracture properties have significant implications for current understanding of the biomechanical conditions underlying aortic dissection.

Kinetic Elephant Trunk Technique: Early Results in Chronic Symptomatic Aortic Dissection Management.

BACKGROUND: The aim was to expand our understanding of the dynamic evolution of the aorta throughout the dissection time course. We investigated how the disease process can be modulated to equalize lumen pressure, enhance perfusion, and stabilize the aorta along its entire length using the kinetic elephant trunk (kET) technique. METHODS: We performed the kET on 9 patients with chronic symptomatic aortic dissection (CSAD) as a primary or secondary intervention, regardless of the chronicity of the dissection. Endovascular scissoring of the intraluminal septum is performed in the infradiaphragmatic dissected aorta to equalize pressure between true and false lumens and allow all branched vessels to be supplied from one lumen. The Streamliner Multilayer Flow Modulator (SMFM), an uncovered cobalt-alloy aortic device, is deployed from the aortic sinus, covering the supra-aortic branches, distally into the distal aorta (primary intervention). In the case of a previous ascending aorta Dacron graft, the SMFM is deployed (secondary intervention) at the level of the Dacron graft so that it is overlapped with the graft and landed in the distal aorta. RESULTS: In the initial study period, all-cause and aortic-related survival were 100%, respectively; all great vessels and visceral branches were patent; and freedom of stroke, end-organ ischemia, paraplegia, and renal failure were 100%. CONCLUSIONS: The kET is a treatment process for managing CSAD. Its simplicity, consistency, and reproducibility in high-risk patients with low morbidity and mortality add to the armamentarium of the cardiovascular specialist. Further assessment of the medium- and long-term outcomes is needed to fully establish the benefits of kET.