ABSTRACT
AIM: The goal of this study was to identify physical characteristics of primary intimal tears in patients arriving to the hospital alive with acute type A aortic dissection using 64-multislice computerized tomography (MSCT) in order to determine anatomic feasibility of endovascular stent-grafting (ESG) for future treatment. METHODS: Radiology database was screened for acute type A aortic dissection since the time of acquisition of the 64-slice CT scanner and cross-referenced with surgical database. Seventeen patients met inclusion criteria. Images were reviewed for number, location, and size of intimal tears and aortic dimensions. Potential obstacles for ESG were determined. RESULTS: Ascending aorta (29%) and sinotubular junction (29%) were the most frequent regions where intimal tears originated. Location of intimal tears in nearly 75% of patients was inappropriate for ESG, and 94% of patients did not have sufficient proximal or distal landing zone required for secure fixation. Only 71% of patients underwent surgical aortic dissection repair after imaging and 86% of entry tears detected on MSCT were confirmed on intraoperative documentation. Only one patient would have met all technical criteria for ESG using currently available devices. CONCLUSION: Location of intimal tear, aortic valve insufficiency, aortic diameter>38 mm are major factors limiting use of ESG for acute type A dissection. Available stents used to treat type B aortic dissection do not address anatomic constraints present in type A aortic dissection in the majority of cases, such that development of new devices would be required.
Subject(s)
Aortic Aneurysm, Thoracic/diagnostic imaging , Aortic Dissection/diagnostic imaging , Blood Vessel Prosthesis , Endovascular Procedures , Patient Selection , Stents , Tomography, X-Ray Computed/methods , Acute Disease , Adult , Aged , Aged, 80 and over , Aortic Dissection/surgery , Aortic Aneurysm, Thoracic/surgery , Female , Follow-Up Studies , Humans , Male , Middle Aged , Reproducibility of Results , Retrospective Studies , Treatment Outcome , Tunica Intima/diagnostic imagingABSTRACT
AIM: Aortic dissection is a life-threatening aortic catastrophe where layers of the aortic wall are separated allowing blood flow within the layers. Propagation of aortic dissection is strongly linked to the rate of rise of pressure (dp/dt) experienced by the aortic wall but the hemodynamics is poorly understood. The purpose of this study was to perform computational fluid dynamics (CFD) simulations to determine the relationship between dissection propagation in the distal longitudinal direction (the tearing force) and dp/dt. METHODS: Five computational models of aortic dissection in a 2D pipe were constructed. Initiation of dissection and propagation were represented in 4 single entry tear models, 3 of which investigated the role of length of dissection and antegrade propagation, 1 of which investigated retrograde propagation. The 5th model included a distal re-entry tear. Impact of pressure field distribution on tearing force was determined. RESULTS: Tearing force in the longitudinal direction for dissections with a single entry tear was approximately proportional to dp/dt and L2 where L is the length of dissection. Tearing force was much lower under steady flow than pulsatile flow conditions. Introduction of a second tear distally along the dissection away from the primary entry tear significantly reduced tearing force. CONCLUSION: The hemodynamic mechanism for dissection propagation demonstrated in these models support the use of ß-blockers in medical management. Endovascular stent-graft treatment of dissection should ideally cover both entry and re-entry tears to reduce risk of retrograde propagation of aortic dissection.
Subject(s)
Aortic Aneurysm/physiopathology , Aortic Aneurysm/surgery , Aortic Dissection/physiopathology , Aortic Dissection/surgery , Blood Vessel Prosthesis Implantation , Endovascular Procedures , Hemodynamics , Models, Cardiovascular , Molecular Dynamics Simulation , Blood Pressure , Blood Vessel Prosthesis , Blood Vessel Prosthesis Implantation/instrumentation , Endovascular Procedures/instrumentation , Humans , Hydrodynamics , Pulsatile Flow , Regional Blood Flow , Stents , Stress, MechanicalABSTRACT
BACKGROUND: Zygomycosis is an opportunistic fungal infection mainly affecting patients with diabetes mellitus, immunodeficiency, and malignancies. The majority of cases in which it has been reported as a posttransplantation complication have been after renal or liver transplantation. There are few instances of rhino-sinusitis and orbital mucormycosis complicating heart transplantation. CASE REPORT: A 38-year-old diabetic man who had undergone heart transplantation returned to the transplantation follow-up clinic 20 days after a successful operation with unilateral periorbital swelling, nasal discharge, and multiple cranial nerve dysfunctions. Multidisciplinary investigations resulted in detection of mucormycosis in the paranasal sinuses and the orbital space, as well as a thrombosis of the cavernous sinus. Surgical ablation of the infected parts, along with antifungal treatment and adjustment of immunosuppressive maintenance, restricted extension of the craniofacial involvement. Allograft function remained undisturbed. CONCLUSION: Early detection of opportunistic infections in transplant recipients plays a big role in preventing dissemination. Fungal infections, including zygomycosis, should be considered for recipients, especially those with risk factors, such as diabetes, who present with local unusual manifestations. Sinonasal and orbital mucormycosis, if diagnosed in timely fashion, can be managed to reduce mortality. Although devastation of one-side facial and ophthalmic structures was inevitable in this case, the overall outcome was acceptable.
