Dissection Membrane Research Articles

Spontaneous Coronary Artery Dissection, Takotsubo Cardiomyopathy, and Venoarterial Extracorporeal Membrane Oxygenation in Pregnancy.

Spontaneous Coronary Artery Dissection, Takotsubo Cardiomyopathy, and Venoarterial Extracorporeal Membrane Oxygenation in Pregnancy.

Six Years' Experience With a Novel Dissection-Specific Stent-Graft to Prevent Distal Stent-Graft-Induced New Entry.

Thoracic endovascular aortic repair (TEVAR) in chronic dissection is associated with a risk for distal stent-graft-induced new entry (dSINE) in up to a quarter of cases. We assess the mid-term outcome of a novel dissection-specific stent-graft (DSSG), which is a custom-made device based on the Cook Alpha platform, with a modified graft design and a distal endovascular elephant trunk without any supporting stent to reduce the radial force on the dissection membrane at the distal landing zone. A retrospective single-center study of chronic dissection patients at high risk of dSINE who received an elective endovascular repair with DSSG from January 2017 to June 2023. The primary outcome is Kaplan-Meier (KM) estimated freedom from dSINE during follow-up. Secondary outcomes included technical success, aortic remodeling, and anatomical evaluation of the distal landing zone in cases with dSINE during follow-up versus those without. Thirty patients (24 males) with a median age of 66 years [range=31-78] underwent elective TEVAR with the DSSG. The majority, n=27 (90%), had previous aortic repair; 7 (23%) had established connective tissue disease, and 6 (20%) had established dSINE after previous stent-graft implantation as an indication for TEVAR. Technical success was achieved in n=29 (97%). Median follow-up was 38.5 months (4.3-76.4), and KM estimated freedom from dSINE at 1 and 3 years was 95.6% (SE 0.043) and 89% (SE 0.081), respectively Four cases developed dSINE during follow-up. The median distance from the distal stent-graft to the coeliac trunk was 74mm (range=18-123) in the dSINE group versus 26mm (range=0-74) in the non-dSINE group (p=0.049). Median proximal tangential aortic angulation in the distal landing zone was 38.5° (range=26°-50°) in the dSINE group compared to 21° (range=3-61°) in the non-dSINE group (p=0.052). The Use of a novel DSSG with low radial force for TEVAR in the setting of chronic dissection is safe and feasible, with remodeling outcomes comparable with standard TEVAR. The reduced distal radial force in the DSSG does not eliminate the risk for dSINE over time, with new entries occurring, particularly in cases where the distal landing zone is in a tortuous aortic segment and not close to the coeliac trunk. Using the novel dissection-specific stent-graft with reduced radial force is safe and feasible but does not completely eliminate the risk of dSINE occurring over time. The exact positioning of the distal stent-graft in a straight aortic segment, close to the coeliac trunk, may be of importance to further mitigate the risk.

Bare Stent Fracture After TEVAR With the Modified Restrictive Bare Stent (RBS) Technique in Type B Aortic Dissections.

The aim was to assess the mid-term aortic remodeling and bare-metal stent (BMS) integrity of the restricted bare stent (RBS) technique reconstruction in aortic dissections. This retrospective cohort study included prospectively collected patients treated with the modified RBS technique between 2017 and 2020. The preoperative, postoperative, and last follow-up computed tomographic (CT) scans were analyzed in the centerline at the mid-descending, celiac trunk (CeT), and the mid-abdominal levels for false lumen (FL) patency, aortic diameter, and true lumen (TL) diameter changes. Bare-metal stent integrity was assessed in the 3-dimensional multiplanar reformats. The median follow-up of the cohort (n=17) was 26 (11, 45) months. The procedure was mainly performed with the Relay NBS endograft (15/17; 88%) + E-XL BMS (17/17; 100%). Postoperative mortality, paraplegia, stroke, renovisceral vessel loss, and type I and III endoleaks were not observed. BMS fractured in 6 patients (6/17; 36%), damaged the dissection flap in 4/17 (24%), and led to the reperfusion of the FL and re-interventions with TEVAR (4/17; 24%). Two patients without FL reperfusion showed stable CT follow-ups 13 and 17 months after the fracture diagnosis. The TL expansion was seen at all landmarks and peaked in the thoracic aorta (+10; 6, 15; p<0.001). The FL thrombosis after modified RBS was only relevant in the thoracic aorta (p<0.001) and at CeT (p=0.003). The aortic diameter was stable in the thoracic aorta and increased at distal landmarks (CeT [+5; 1, 10; p=0.001]; mid-abdominal [+3; 1, 5; p=0.004]). The modified RBS technique could not stop aortic growth below the diaphragm and prevent new membrane rupture due to the fractures of the BMS and consecutive flap damage with the reperfusion of the FL. The treatment of complicated type B aortic dissections with TEVAR has become a standard. Particularly, patients with true lumen collapse and malperfusion may benefit from a more aggressive treatment strategy including proximal TEVAR and distal bare-metal stent implantation to re-open the true lumen and to prevent distal stent-induced new entry. However, this study reports the challenges of this approach with a high rate of bare-metal stent fractures during the follow-up. The fractures that occurred at the site of vertical nitinol bridges led to the dissection membrane ruptures and the reperfusion of the false lumen with consecutive dilatation. A close follow-up is mandatory to detect this complication and to treat the patients with TEVAR extension.

Computational Fluid Dynamics Analysis of the Effect of a New Dissection Specific Stent Graft on Preventing Distal Stent Graft Induced New Entry (dSINE) in Patients With Chronic Type B Aortic Dissection

Objective: Distal stent graft induced new entry (dSINE) is being increasingly reported after TEVAR for chronic type B aortic dissection (cTBAD). In addition to aortic wall fragility, stent graft oversizing due to the discrepancy between the sizes of proximal and distal landing zones and the less compliant dissection flap to the expansion of the stent graft carry a higher risk of a new intimal tear. To address these risk factors, a dissection specific stent graft (DSSG) was designed to include features such as: no proximal barbs, a customised longer body length with substantial taper, reduced radial force in the second and third distal stents that are sited internally to avoid any contact with the dissection membrane, and removal of the final stent, leaving 30 mm of unsupported Dacron fabric (“endovascular elephant trunk”) (Fig. 1). The combination of patient specific anatomy and the implanted endograft brings about changes in haemodynamic of the stented and non-stented regions that can have consequences on flow patterns and shear stress distributions. As such, wall shear stress (WSS) is of particular interest, and computational fluid dynamics (CFD) can provide information on WSS. As a continuation of previous work reporting midterm clinical effectiveness of DSSG with low rates of dSINE,1 the present study focuses on identifying haemodynamic properties (WSS) of DSSG compared with those of standard thoracic stent graft (STSG) by means of CFD simulations.

Changing Management of Type B Aortic Dissections.

The purpose of this manuscript is to review recent trends in the management of acute type B aortic dissection. Due to its efficacy and low morbidity, thoracic endografting has rapidly been adopted as the treatment of choice for most patients with malperfusion or rupture as a consequence of acute aortic dissection. This technology is increasingly applied to patients without rupture or malperfusion, so-called "uncomplicated" dissections, to reduce the incidence of late aneurysmal degeneration in the ungrafted segments of the thoracoabdominal aorta. A variety of techniques have been proposed, including intentional rupture of the dissection membrane to obliterate the false lumen as well as the candy-plug technique to eliminate retrograde flow in the false lumen.

Ultrasound Criteria for Diagnosing Spontaneous Cervical Artery Dissections.

Spontaneous dissection of brain-supplying cervical arteries, which also includes findings after minor injuries, is one of the main causes of ischaemic strokes in young adults. Strokes due to dissection are usually due to arterio-arterial embolism. They are rarely the first symptom of dissection because an intraluminal thrombus must first develop. Therefore, early diagnosis of dissection can contribute to stroke prevention - through immediate therapy with anticoagulants or antiplatelet drugs. This article describes the diagnostic criteria and typical findings of spontaneous dissection, in which no dissecting membrane is to be expected as in aortic dissection. Traumatic dissections following blunt or penetrating injuries also present with different findings. Examiners should be aware of possible differential diagnoses whose ultrasound image may mimic a dissection. A frequently occurring but avoidable cause of misdiagnosis is idiopathic carotidynia. Ultrasound also enables differentiation between dissection and vasculitis or carotid web and detection of normal variants such as fenestration of the vertebral artery. Further possibilities for misdiagnosis may arise in the presence of a variant of the ascending pharyngeal artery or in extracranial vasospasm. The different imaging techniques for the detection of a dissection are complementary, as false-negative findings occur with all techniques; no method serves as the gold standard. In any case, ultrasound can make an important contribution to the detection of a dissection, and it is worth knowing the diagnostic criteria.

Aortic Wall Injury After Thoracic Stent Grafts: Vigilance Is Required!

The occurrence of stent-induced new entry tears (SINE) in patients undergoing thoracic endovascular aortic repair (TEVAR) for aortic dissection is an important complication associated with high reintervention and death. In this issue of The Annals of Thoracic Surgery, by systematically reviewing all cross-sectional imaging after TEVAR for all indications, Doberne and colleagues,1 from Duke University, have identified the occurrence of stent-graft induced aortic wall injury, or SAWI, a broader term that encompasses all forms of aortic wall injury after TEVAR—including SINE, which occurs at the interface of a stent graft with a pre-existing dissection membrane.

Impact of true or false lumen renal perfusion after type B aortic dissection on renal volume.

The aim of this study was to analyse the influence of true, false, and combined lumen perfusion of renal arteries on mid- and long-term kidney volume in patients with type B aortic dissection (TBAD). Retrospective analysis of patients diagnosed with a TBAD between 2008 and 2015 in a single high-volume European center. The origin of the renal arteries was evaluated on a dedicated 3D workstation (TeraRecon Inc., San Mateo, CA, USA) and coded as either arising from the true lumen (TL), false lumen (FL) or from a combination of both (CL). Additional evaluated anatomical parameters were renal volume, length, width, and depth of the kidneys. Measurements were recorded at the time of diagnosis (T0) and at 1-month (T1), 6-months (T2), 18-months (T3) and 36-month of follow-up time (T4). A total of 131 renal arteries and kidneys were evaluated in 69 patients. Mean age was 64±13 years and 77% were male. The absolute number and percentage of assessed renal arteries/kidneys was 131 (100%) at T0, 89 (68%) at T1, 73 (56%) at T2, 57 (44%) at T3 and 43 (44%) at T4. At the time of diagnosis, 71.6% renal arteries originated from the TL, 19.1% from the FL and 9.2% from a CL. TEVAR was performed in 92.7% patients and nine patients had additional renal artery stenting. At T0 the mean renal volume was 212.1±70.9cm3, 178±61.2 in women versus 222.2±70.6 in men (P=0.002). Forty-three percent of the patients had a renal volume reduction ≥15% from T0 to their last available CTA. Mixed model analysis showed a significant overall renal volume reduction of 13.7cm3 from T0 to T4 (P<0.05). No significant differences in renal-volume reduction were observed depending on origin of the renal artery, though an estimated reduction of renal volume from T0 to T4 of 40.8 cm3 was seen when the kidneys were perfused by a CL, while TL perfusion only caused a reduction of 15.6 cm3 and no relevant volume change over time was observed when the renal artery originated from FL. Alongside a renal volume reduction, mixed model analysis also showed a significant serum-creatinine increase, from 0.8618mg/at T0 to 1.38±0.56 mg/dL at T4 (P<0.001), as well as a significant glomerular filtration rate reduction over time, from > 60mL/min at T0 to 49±13 mL/min at T4 (P<0.001). A negative correlation was observed between creatinine values and renal volume change, while a positive correlation was observed between GFR and renal volume change (P<0.001). There is a significant mid-term renal-volume reduction in patients with TBAD, independent of the origin of the renal arteries. Albeit not statistically significant, combined renal artery perfusion may lead to a greater volume reduction, potentially secondary to a relevant dynamic compression by the dissection membrane. Further multicentre studies are warranted to determine the effect on long-term renal function and on possible preventive strategies.

Entry Tear Dominance at CT Angiography Predicts Long-term Clinical Outcomes in Aortic Dissection: Another Piece of the Puzzle.

Entry Tear Dominance at CT Angiography Predicts Long-term Clinical Outcomes in Aortic Dissection: Another Piece of the Puzzle.

Multi‐layered tissue models in patient‐specific simulations of aortic dissection

AbstractIn aortic dissections blood flows not only in the regular, true lumen but also between separated lamellae within the media of the aortic wall, in the so‐called false lumen. Both lumina are separated by a dissection membrane, which may move substantially during the cardiac cycle, linking blood flow and vessel deformation. We employ strongly coupled fluid‐structure interaction simulations incorporating an anisotropic, fiber‐reinforced, hyperelastic continuum including layer‐specific tissue parameters.

Early Experience With a Novel Dissection-Specific Stent-Graft to Prevent Distal Stent-Graft-Induced New Entry Tears After Thoracic Endovascular Repair of Chronic Type B Aortic Dissections

The aim was to report short and mid-term outcomes of a novel, investigational, dissection-specific stent-graft (DSSG), specifically designed to address the features of chronic type B aortic dissection (CTBAD) and reduce the risk of distal stent-graft-induced new entry tears (dSINE). A retrospective single center cohort study of all patients undergoing TEVAR with the DSSG for CTBAD from January 1, 2017 to January 31, 2020. The DSSG, which is a modified stent-graft based on the Cook Zenith Alpha Thoracic platform, has no proximal barbs, and a customized longer body length with substantial taper. The second and third distal Z-stents are sited internally to avoid any contact of the metal skeleton with the dissection membrane and have reduced radial force, while the most distal stent was removed creating a distal 30 mm unsupported Dacron graft. Sixteen patients (13 males, 3 females) with a median age of 66 years (range 31-79 years) underwent elective TEVAR of CTBAD using the DSSG. Six patients (38%) had an underlying connective tissue disorder. The median tapering was 10 mm (range 4 mm-21 mm) and median length 270 mm (range 210-380 mm). Technical success was achieved in all but one case (96%). One patient died within 30 days, due to retrograde type A dissection with cardiac tamponade. The 30-day rate of stroke, spinal cord ischemia, and re-interventions was 0%. After median imaging follow-up time of 17 months (range 1-31 months), one patient developed a dSINE 4 months after the index procedure. After median survival follow-up of 23 months (range 2-35 months), one late death occurred due to traumatic brain injury, while no aortic-related death occurred during follow-up. Complete false lumen (FL) thrombosis was achieved in 9 patients while the remaining 6 showed partial FL thrombosis. No instances of diameter increase at the level oftreated aortic segment were noted with serial measurements showing either stable (n = 7) or decreased (n = 8) maximal transverse diameter. Use of a novel DSSG with low radial force for TEVAR in the setting of CTBAD is safe and feasible. This early real-world experience shows promising mid-term effectiveness with low rates of dSINE or unplanned re-interventions and satisfactory aortic remodeling during follow-up. Longer follow-up is needed, however, before any firm conclusions can be drawn.

The impact of dissection membrane motility on mid-term aortic remodelling after thoracic endovascular repair.

The aim of this study was to assess preoperative dissection flap motility and to evaluate its impact on the aortic remodelling and the development of distal stent-induced new entry after thoracic endovascular aneurysm repair (TEVAR)/frozen elephant trunk (FET). Patients with primary or residual type B dissections were included in a retrospective study with transoesophageal echocardiography analysis of the preoperative dissection flap motility assessed by the true lumen (TL) strain. Three-dimensional computing tomography centreline reconstructions before TEVAR/FET and during the follow-up were conducted to measure aortic remodelling: false lumen thrombosis, TL expansion and aortic diameters at 10 and 20 cm downstream the left subclavian artery, at the coeliac trunk and in the infrarenal aorta. All continuous variables are reported as median with first and third quartiles. Fifty-six consecutive patients were treated with TEVAR (n = 45) or FET (n = 11) in the acute (n = 16), subacute (n = 16) and chronic (n = 24) dissection phase. At a median follow-up of 6 (3-12) months, they showed a favourable TL expansion in the descending aorta, significantly higher in the acute [+9 mm (5-12); P < 0.001] and subacute groups [+5 mm (3-8); P = 0.039] than in the chronic group [+2 mm (0-5)]. The dissection flap motility parameter TL strain was superior in the acute (P = 0.006) and subacute (P = 0.035) groups in comparison to the chronic group. The motile flap [TL strain >22.5% (median)] was associated with a higher TL expansion rate in the thoracic aorta (P = 0.009) and a comparable distal stent-induced new entry incidence (overall: 16%) in comparison to the immobile flap (P = 0.89). The intraoperative assessment and the inclusion of the dissection flap motility parameters in the decision-making during TEVAR/FET may refine the distal endograft sizing for an improved remodelling of the TL.

Implicit Modeling of Patient‐Specific Aortic Dissections with Elliptic Fourier Descriptors

AbstractAortic dissection is a life‐threatening vascular disease characterized by abrupt formation of a new flow channel (false lumen) within the aortic wall. Survivors of the acute phase remain at high risk for late complications, such as aneurysm formation, rupture, and death. Morphologic features of aortic dissection determine not only treatment strategies in the acute phase (surgical vs. endovascular vs. medical), but also modulate the hemodynamics in the false lumen, ultimately responsible for late complications. Accurate description of the true and false lumen, any communications across the dissection membrane separating the two lumina, and blood supply from each lumen to aortic branch vessels is critical for risk prediction. Patient‐specific surface representations are also a prerequisite for hemodynamic simulations, but currently require time‐consuming manual segmentation of CT data. We present an aortic dissection cross‐sectional model that captures the varying aortic anatomy, allowing for reliable measurements and creation of high‐quality surface representations. In contrast to the traditional spline‐based cross‐sectional model, we employ elliptic Fourier descriptors, which allows users to control the accuracy of the cross‐sectional contour of a flow channel. We demonstrate (i) how our approach can solve the requirements for generating surface and wall representations of the flow channels, (ii) how any number of communications between flow channels can be specified in a consistent manner, and (iii) how well branches connected to the respective flow channels are handled. Finally, we discuss how our approach is a step forward to an automated generation of surface models for aortic dissections from raw 3D imaging segmentation masks.

Adjunctive endovascular balloon fracture fenestration for chronic aortic dissection.

Positive remodeling after thoracic endovascular aortic repair (TEVAR) for chronic thoracic aortic dissection is variable due to incomplete distal seal and retrograde false lumen perfusion. We assessed the outcomes of adjunctive balloon fracture fenestration (BFF) during TEVAR in patients with chronic aortic dissection complicated by negative remodeling. From June 2013 to January 2016, 49 patients with chronic aortic dissection complicated by aneurysm due to negative remodeling underwent TEVAR with BFF. Contrast-enhanced computed tomography was performed before discharge, at 3 to 6months, and annually. Intraoperatively, endovascular stent graft expansion was achieved in all patients. There was 1 hospital death due to visceral malperfusion related to acute-on-chronic dissection noted before planned BFF. There were no occurrences of paraplegia, 3 patients had stroke, and 3 had acute renal failure. Survival at 1year was 91%. Late reintervention for incomplete false lumen exclusion was required in 16 patients and freedom from reintervention was 75% at 1year. Thirty-six patients (73.5%) had complete false lumen thrombosis through the treated segment. True lumen area increased following TEVAR with BFF and continued to incrementally expand with subsequent aortic remodeling at 1-year follow-up. Thirteen patients had positive remodeling, defined as thrombosis of false lumen, ≥10% decrease in aortic dimension, and ≥10% increase in true lumen diameter. Patients with positive remodeling had an average decrease of 11mm in maximal aortic diameter at final follow-up. BFF of chronic dissection membrane is a beneficial adjunct to TEVAR during short-term follow-up and may promote positive aortic remodeling and is worthy of further study.

Fluid-structure interaction simulations of patient-specific aortic dissection.

Credible computational fluid dynamic (CFD) simulations of aortic dissection are challenging, because the defining parallel flow channels-the true and the false lumen-are separated from each other by a more or less mobile dissection membrane, which is made up of a delaminated portion of the elastic aortic wall. We present a comprehensive numerical framework for CFD simulations of aortic dissection, which captures the complex interplay between physiologic deformation, flow, pressures, and time-averaged wall shear stress (TAWSS) in a patient-specific model. Our numerical model includes (1) two-way fluid-structure interaction (FSI) to describe the dynamic deformation of the vessel wall and dissection flap; (2) prestress and (3) external tissue support of the structural domain to avoid unphysiologic dilation of the aortic wall and stretching of the dissection flap; (4) tethering of the aorta by intercostal and lumbar arteries to restrict translatory motion of the aorta; and a (5) independently defined elastic modulus for the dissection flap and the outer vessel wall to account for their different material properties. The patient-specific aortic geometry is derived from computed tomography angiography (CTA). Three-dimensional phase contrast magnetic resonance imaging (4D flow MRI) and the patient's blood pressure are used to inform physiologically realistic, patient-specific boundary conditions. Our simulations closely capture the cyclical deformation of the dissection membrane, with flow simulations in good agreement with 4D flow MRI. We demonstrate that decreasing flap stiffness from [Formula: see text] to [Formula: see text] kPa (a) increases the displacement of the dissection flap from 1.4 to 13.4 mm, (b) decreases the surface area of TAWSS by a factor of 2.3, (c) decreases the mean pressure difference between true lumen and false lumen by a factor of 0.63, and (d) decreases the true lumen flow rate by up to 20% in the abdominal aorta. We conclude that the mobility of the dissection flap substantially influences local hemodynamics and therefore needs to be accounted for in patient-specific simulations of aortic dissection. Further research to accurately measure flap stiffness and its local variations could help advance future CFD applications.

Complete Entry and Re-entry Neutralization protocol in endovascular treatment of aortic dissection.

68 patients qualified for endovascular treatment of an acute or chronic aortic dissection. Computed tomography was performed post-operatively to assess aortic remodeling after 1/6/12/24/36 months. the 30-day mortality rate was 4.4%. In 29 cases (43%) unfavorable remodeling was noted in the follow-up. The most important factors leading to unfavorable remodeling were: uncovered re-entry tear including the infra-renal segment, no relining of dissection membranes and insufficient coverage of the descending aorta. We analyzed these factors to develop the CERN protocol. This concept consists of six basic rules: A. cover all entry tears, B. amplify the BMS radial force, C. use the STABILISE technique, D. consider using thrombus plugs, E. avoid stenting the visceral branches, F. spare the intercostal and lumbar side branches. CERN improves the rate of favorable remodeling from 25% to 85% (P = 0.0067). Introduction of the Complete Entry and Re-entry Neutralization protocol improves the rate of favorable remodeling following endovascular treatment of aortic dissection in mid-term follow-up in patients with diffused aortic dissection.

Successful Resuscitation Using Extracorporeal Membrane Oxygenation of 2 Patients With Severe Liver Rupture: A Case Report

Extracorporeal membrane oxygenation is a rescue treatment for respiratory or cardiac failure. Its use is limited in patients predisposed to bleeding due to heparin administration. We present 2 patients with deranged coagulation after liver rupture successfully treated by extracorporeal membrane oxygenation. One patient with cardiac arrest developed a liver laceration during resuscitation. Liver suture was performed, but acute respiratory distress syndrome (PaO2/fraction of inspired oxygen, 50) necessitated venovenous extracorporeal membrane oxygenation. The other patient suffered hemothorax, thoracic aorta dissection, and liver rupture. Liver segments VI and VII were resected. Endovascular aneurysm repair of aortic dissection and venoarterial extracorporeal membrane oxygenation were performed. Both patients survived without neurological sequelae.

High intimal flap mobility assessed by intravascular ultrasound is associated with better short-term results after TEVAR in chronic aortic dissection

Thoracic endovascular aortic repair (TEVAR) in chronic aortic dissection remains controversial. We analysed whether a high intimal flap mobility (IFM) of the dissection membrane has an impact on aortic remodelling after TEVAR in chronic Type B aortic dissection. Patients undergoing TEVAR with intravascular ultrasound (IVUS) were analysed and IFM was calculated. High IFM was defined as maximum flap amplitude >3 mm. For determining aortic remodelling, the degree of true lumen (TL) expansion was analysed in the last available follow-up CT. Fifty-two patients (63.6 ± 15.4 years) with a mean follow-up of 26.6 ± 20.7 months were analysed. The mobile flap group (n = 29) showed higher absolute TL expansion at the distal stent-graft (5.9 ± 3.1 vs. 3.3 ± 5.4 mm; p = 0.036) and a higher increase in TL diameter (18 ± 10 vs. 9 ± 15%; p = 0.017) compared to the non-mobile group (n = 23). Basic TEVAR-related outcome characteristics were comparable, but the mobile intimal flap group showed a lower re-intervention rate (3 vs. 8pts.; p = 0.032) in chronic dissections. High IFM in chronic Type B aortic dissection is linked to improved aortic remodelling and is associated with a lower re-intervention rate over time. IVUS assessment of IFM in chronic Type B aortic dissection might be helpful in identifying patients with better remodelling after TEVAR.

Order Indication Solicitation to Assess Clinical Laboratory Test Utilization: D-Dimer Order Patterns as an Illustrative Case

Background: A common challenge in the development of laboratory clinical decision support (CDS) and laboratory utilization management (UM) initiatives stems from the fact that many laboratory tests have multiple potential indications, limiting the ability to develop context-specific alerts. As a potential solution, we designed a CDS alert that asks the ordering clinician to provide the indication for testing, using D-dimer as an exemplar. Using data collected over a nearly 3-year period, we sought to determine whether the indication capture was a useful feature within the CDS alert and whether it provided actionable intelligence to guide the development of an UM strategy. Methods: We extracted results and ordering data for D-dimer testing performed in our laboratory over a 35-month period. We analyzed order patterns by clinical indication, hospital service, and length of hospitalization. Results: Our final data set included 13,971 result-order combinations and indeed provided actionable intelligence regarding test utilization patterns. For example, pulmonary embolism was the most common emergency department indication (86%), while disseminated intravascular coagulation was the most common inpatient indication (56%). D-dimer positivity rates increased with the duration of hospitalization and our data suggested limited utility for ordering this test in the setting of suspected venous thromboembolic disease in admitted patients. In addition, we found that D-dimer was ordered for unexpected indications including the assessment of stroke, dissection, and extracorporeal membrane oxygenation. Conclusions: Indication capture within a CDS alert and correlation with result data can provide insight into order patterns which can be used to develop future CDS strategies to guide appropriate test use by clinical indication.

Echocardiography-Guided False Lumen Catheterization for “Cheese-Wire” Technique in Complicated Type A Aortic Dissection

Endovascular treatment of both type A and type B aortic dissections complicated by organ malperfusion is gaining increasing interest and evidence. Different fenestration techniques of the dissection membrane have already been described. We present a 53-year-old patient with complicated type A aortic dissection after previous repair of the ascending aorta. The patient was treated with dissection membrane fenestration and "cheese-wire" technique. Owing to the mobility of the dissection flap, we encountered problems to perforate the dissection membrane with the use of a needle. Finally, on transesophageal echocardiography (TEE), a small dynamic dissection flap was visualized in the aortic arch, which could be catheterized by TEE for guidance. Downward traction of the through-wire caused infrarenal intima accumulation. Iliac outflow obstruction could be solved by placement of a bare-metal stent. Extensive screening for dynamic dissection of (re)-entry holes with the use of TEE is a valuable auxiliary in case needle perforation is difficult to achieve in complicated type A or B dissections.