Management of Acute Aortic Syndrome and Chronic Aortic Dissection

Overall survival, cause of death and time interval between diagnosis and death after Stanford type B acute aortic dissection (TBAAD)

OBJECTIVES

This study aimed to assess survival rates and the causes of both early and late mortality in patients with Stanford type B acute aortic dissection (TBAAD).

METHODS

A retrospective analysis was conducted on all consecutive patients presenting with TBAAD from 2000 to 2018 at a single tertiary care centre. The primary end-point was early (<3 months) and late (>3 months) survival following TBAAD, with causes of both early and late mortality evaluated.

RESULTS

A total of 274 patients, with a mean age of 64 ± 13 years, were included. Among these, 155 patients (57%) presented with uncomplicated TBAAD, including 52 (19%) identified as high-risk, and 119 patients (43%) had complicated TBAAD. Early aorta-related mortality occurred in 9 patients (3.3%), all within the complicated TBAAD group. The median follow-up period for the entire cohort was 8.5 years [95% confidence interval (CI) 7.6-11.2]. Long-term survival was significantly higher in patients with uncomplicated TBAAD compared to those with complicated TBAAD (P < 0.001). Both complicated and high-risk uncomplicated TBAAD cases required significantly more interventions in the chronic phase (>3 months) compared to uncomplicated TBAAD cases [hazard ratio (HR) 9.8, 95% CI 6.4-15.4, P < 0.001; HR 3.3, 95% CI 2.1-5.1, P < 0.001).

CONCLUSIONS

Complicated TBAAD presents the greatest risk for aorta-related mortality and interventions. Patients with high-risk uncomplicated TBAAD are also notable for an increased rate of aorta-related mortality and interventions. Thorough evaluation of clinical and anatomical characteristics is essential for determining the optimal therapeutic approach.

Investigation of Type A Aortic Dissection Using Computational Modelling

Aortic dissection is a catastrophic failure of the endothelial wall that could lead to malperfusion or rupture. Computational modelling tools may help detect arterial damage. Technological advancements have led to more sophisticated forms of modelling being made available to low-grade computers. These devices can create 3D models with clinical data, where the clinical blood pressure waveforms' model can be used to form boundary conditions for assessing hemodynamic parameters, modelling blood flow propagation along the aorta to predict the development of cardiovascular disease. This study presents patient-specific data for a rare case of severe Type A aortic dissection. CT scan images were taken nine months apart, consisting of the artery both before and after dissection. The results for the pre-dissection CT showed that the pressure waveform at the ascending aorta was higher, and the systolic pressure was lagging at the descending aorta. For the post-dissection analysis, we observed the same outcome; however, the amplitude for the waveform (systolic pressure) at the ascending aorta increased in the false lumen by 25% compared to the true lumen by 3%. Also, the waveform peak (systolic) was leading by 0.01 s. The hemodynamic parameter of wall shear stress (WSS) predicted the aneurysm's existence at the ascending aorta, as well as potential aortic dissection. The high WSS contours were located at the tear location at the peak blood flow of 0.14 s, which shows the potential of this tool for earlier diagnosis of aortic dissection.

Transcatheter electrosurgical septotomy technique for chronic postdissection aortic aneurysms

Aortic dissection often results in chronic aneurysmal degeneration due to progressive false lumen expansion. Thoracic endovascular aortic repair and other techniques of vessel incorporation such as fenestrated-branched or parallel grafts have been increasingly used to treat chronic postdissection aneurysms. True lumen compression or a vessel origin from the false lumen can present considerable technical challenges. In these cases, the limited true lumen space can result in inadequate stent graft expansion or restrict the ability to reposition the device or manipulate catheters. Reentrance techniques can be used selectively to assist with target vessel catheterization. Transcatheter electrosurgical septotomy is a novel technique that has evolved from the cardiology experience with transseptal or transcatheter aortic valve procedures. This technique has been applied in select patients with chronic dissection to create a proximal or distal landing zone, disrupt the septum in patients with an excessively compressed true lumen, or connect the true and false lumen in patients with vessels that have separate origins. In the present report, we summarize the indications and technical pitfalls of transcatheter electrosurgical septotomy in patients treated by endovascular repair for chronic postdissection aortic aneurysms.

A rare presentation of triple-barrel aortic dissection in a Ghanaian male

Acute aortic dissection in unusual/rare circumstances may become chronic and multi lumen. A high clinical acumen, examination and investigations in the acute setting, may help reduce late/misdiagnosis and complications in low resource settings.

Mid-term Outcomes of Physician-Modified Fenestrated or Branched Endovascular Repair for Post-dissection Thoracoabdominal Aortic Aneurysms

PURPOSE

To report the early experience and mid-term outcomes of physician-modified fenestrated or branched endovascular repair (PM-F/BEVAR) for patients with post-dissection thoracoabdominal aortic aneurysm (PD-TAAA).

METHODS

PD-TAAA patients treated with PM-F/BEVAR between December 2014 and September 2020 in our institution were retrospectively analyzed.

RESULTS

Out of the 39 patients, technical success defined as successful deployment of all stent grafts with patent target vessels (TVs) and exclusion of the lesion without type I or III endoleak was achieved in 35 patients (89.7%). A total of 126 TVs were successfully reconstructed. Thirty-day mortality was 0%. Seven major adverse events occurred including one acute kidney injury, four renal infarctions, one retroperitoneal hematoma and one left renal artery occlusion. Seven type II endoleak and three type III endoleak were detected. During a mean 29.4 ± 15.5 months follow-up period, the mortality was zero. Three renal arteries and one external iliac artery occluded in four patients. No other new onset major adverse event occurred. No patient required reintervention. One type II endoleak spontaneously resolved, while the remaining six remained stable. One early type III endoleak diminished, and one new type III endoleak occurred at 2 months. The primary patency of TV was 96.8% (120/124). Shrinkage or stability of aneurysm diameter can be observed in 38 patients (97.4%). The false lumen thrombosis rate was 89.7% (35/39).

CONCLUSIONS

The present study showed encouraging results of PM-F/BEVAR for treatment of PD-TAAAs.

LEVEL OF EVIDENCE

Level 4, Case Series.

Reverse "cheese wire" fenestration for abdominal aortic dissection repair: a case report and literature review

Background

Aortic dissection is one of the most common emergency condition leading to internal organs or lower limb ischemia and aortic rupture. Herein, we described a reverse “cheese wire” endovascular fenestration repair (CWFER) in a patient with complicated abdominal aortic dissection which had never been reported.

Case presentation

A 62-year-old male presented abdominal tear-like pain and acute ischemia of the right lower extremity during the endovascular treatment of celiac trunk aneurysms. Computed tomography angiography (CTA) and digital subtraction angiography (DSA) showed abdominal aortic type B dissection with acute ischemia of the right lower extremity preoperatively. After a detailed preoperative examination, the patient then was performed a reverse CWFER. So far, the patient has been followed-up for 6 months, postoperative CTA demonstrated good stent-graft expansion and perfusion of bilateral common iliac arteries; also, no endoleak was detected.

Conclusions

The right iliac artery in this patient supplied by false lumen, which lead to acute ischemia of the right lower extremity, needed to be treated as an emergency and dealt with promptly. CWFER is a very high-risk treatment that requires the rich experience of vascular surgeon and accurate assessment of aortic dissection. After interventional treatment, the patient recovered uneventfully after 6 months’ follow-up.

Supplementary information

The online version contains supplementary material available at 10.1186/s12893-022-01581-4.

Computed Tomography Angiography Assessment of Acute Aortic Syndromes: Classification, Differentiating Imaging Features, and Imaging Interpretation Pitfalls

An acute aortic syndrome (AAS) is an important life-threatening condition that requires early detection and management. Acute intramural hematoma (IMH), aortic dissection (AD) and penetrating atherosclerotic ulcer (PAU) are included in AAS. ADs can be classified using the well-known Stanford or DeBakey classification systems. However, these classification systems omit description of arch dissections, anatomic variants, and morphologic features that impact outcome. The Society for Vascular Surgery and Society of Thoracic Surgeons (SVS-STS) have recently introduced a classification system that classifies ADs according to the location of the entry tear (primary intimomedial tear, PIT) and the proximal and distal extent of involvement, but does not include description of all morphologic features that may have diagnostic and prognostic significance. This review describes these classification systems for ADs and other AAS entities as well as their limitations. Typical computed tomography angiography (CTA) imaging appearance and differentiating features of ADs, limited intimal tears (LITs), IMHs, intramural blood pools (IBPs), ulcer-like projections (ULPs), and PAUs will be discussed. Furthermore, this review highlights common imaging interpretation pitfalls, what should be included in a comprehensive CTA report, and provides a brief overview of current management options.

Hemodynamic Effects of Multiple Overlapping Uncovered Stents on Aortic Dissection: Surgical Strategies and Implications for False Lumen Thrombosis

PURPOSE

Multiple overlapping uncovered stents (MOUS) are employed to promote false lumen thrombosis in the aortic dissections (AD), when the tears are in close vicinity to the branch vessels. However, the overall rate of false lumen thrombosis remains unsatisfactory. This study was performed to investigate the hemodynamic influence of MOUS on aortic dissection to shed some light on the mechanism of post-stenting false lumen thrombosis.

METHODS

An anatomically accurate computational fluid dynamics model was developed to investigate the hemodynamics of AD. A parametric study was carried out to demonstrate the hemodynamic influence of MOUS in various post-surgery scenarios featuring the representative surgical strategies involving MOUS.

RESULTS

The use of reduced-porosity MOUS slowed the blood flow in the false lumen and decreased the wall shear stress. MOUS depressed the false lumen and enlarged the true lumen, without significantly altering the blood outflow distribution among the branch vessels. Compared with MOUS-alone and stent graft-alone scenarios, the combination of MOUS and stent graft generated a substantially large region of stagnant flow. The active flow was confined to an area in close vicinity to the tears covered by the MOUS, which perfuse the right renal artery in the false lumen.

CONCLUSIONS

MOUS helps to generate a favored hemodynamic environment for thrombus formation in the false lumen. Application of MOUS along with covered stent grafts may represent a more effective treatment for AD than utilizing MOUS or stent graft alone.

Association between acute aortic dissection and the distribution of aortic calcification

Objective

Aortic calcification (AC) is associated with increased risks of cardiovascular events and mortality. Numerous studies have explored the association between calcification and abdominal artery aneurysm. However, evidence regarding the association between AC and acute aortic dissection (AAD) is limited. We aimed to evaluate the association between AC-related variables and the development of intimal tear (IT) in patients with AAD.

Methods

We conducted a retrospective observational study involving 64 patients with type A AAD and 32 patients with type B AAD from February, 2011 to January, 2017 at a tertiary referral medical center in Taiwan. We used the default analysis module “calcification score analysis” to calculate all the calcification variables, including AC scores and volume.

Results

We identified an association between AC and AAD. Patients with AAD had a greater AC volume in the aortic arch and greater AC scores for both the ascending aorta and the aortic arch than did patients without AAD. However, hypertension and coronary artery disease, rather than AC remained to be the independent risk factor for AAD in multivariate analysis. Patients with type A AAD had greater mean and cumulative AC volumes in the aortic arch, greater cumulative AC volumes in the whole aorta and higher cumulative AC scores in the aortic arch than did patients with type B AAD. ACs were superimposed on ITs in nearly half of the patients with AAD. In patients with type A AAD, AC was more commonly located distal to the IT and farther from the IT.

Conclusions

We identified the associations between AC-related variables and the location of IT in patients with AAD. However, AC was not an independent risk factor for AAD. The distribution of AC was different between patients with type A and type B AAD.

Hemodynamic consequences of a multilayer flow modulator in aortic dissection

Aortic dissections are challenging for it remains perplexing to determine when surgical, endovascular, or medical therapies are optimal. We studied the effect of the multilayer flow modulator (MFM) device in patients with different forms of type-B aortic dissections. CT scans were performed pre-, immediately post-MFM implantation, and multiple times within a 24-month follow-up. Three-dimensional reconstructions were created from these scans and the multilayer or single-layer mesh device placed virtually into the true lumen. We observed that MFM device can sufficiently restore flow perfusion, reduce the false lumen, eliminate local flow recirculation, and reduce wall shear stress distribution globally. Single-layer devices can reduce false lumen dimensions; however, they generate local disturbance and recirculation zones in selected areas at specific time points. Moreover, in polar extremes of dissection, the MFM device restored flow to vital organs perfusing vessels independent of effects on luminal patency. Management of aortic dissections should focus on modulation of blood flow, suppression of local recirculation, and restoration of vital organ perfusion rather than primarily restoring vascular lumen morphology. While the latter restores the geometry of the true lumen, only the former restores homeostasis. Graphical abstract.

Successful treatment of unexpected complication during aortic stent-grafting: retrieval of broken stent-graft tip by coaxial technique

Thoracic aortic endovascular repair (TEVAR) is increasingly preferred as a treatment of choice in thoracic aortic diseases. Intravascular foreign body is one of the TEVAR-related complications similar to the other endovascular operations. Here, to the our best knowledge for the first time in the English literature, this report presents an extremely rare complication of a broken and stuck tip part of aortic stent-graft in the intravascular space and successful removal by using the coaxial technique. Thoracic aortic endovascular repair (TEVAR) has been increasingly preferred as the treatment of choice in thoracic aortic diseases (1). Endovascular treatment has been gaining popularity compared with open surgery due to its less invasive approach and rapid application, and allows the patient to easily return to daily life (2). However, TEVAR is associated with several specific complications including paraplegia, stroke, vascular injuries and local complications. These complications depend on vascular or nonvascular comorbidities, vascular anatomy, equipment, and experience of the provider (3-6). Intravascular foreign body could be among TEVAR-related complications similar to other endovascular operations (7). Several types of equipment, including guidewire, vascular sheath, or suboptimally uncoiled stents may get stuck in the intravascular space, causing complications (8). Herein, to the best of our knowledge, we present the first report in the English literature of broken and stuck tip part of an aortic stent-graft in the intravascular space and its successful removal using the coaxial technique.

Clinical validation and assessment of aortic hemodynamics using computational fluid dynamics simulations from computed tomography angiography

Background

Hemodynamic information including peak systolic pressure (PSP) and peak systolic velocity (PSV) carry an important role in evaluation and diagnosis of congenital heart disease (CHD). Since MDCTA cannot evaluate hemodynamic information directly, the aim of this study is to provide a noninvasive method based on a computational fluid dynamics (CFD) model, derived from multi-detector computed tomography angiography (MDCTA) raw data, to analyze the aortic hemodynamics in infants with CHD, and validate these results against echocardiography and cardiac catheter measurements.

Methods

This study included 25 patients (17 males, and 8 females; a median age of 2 years, range: 4 months–4 years) with CHD. All patients underwent both transthoracic echocardiography (TTE) and MDCTA within 2 weeks prior to cardiac catheterization. CFD models were created from MDCTA raw data. Boundary conditions were confirmed by lumped parameter model and transthoracic echocardiography (TTE). Peak systolic velocity derived from CFD models (PSV_CFD) was compared to TTE measurements (PSV_TTE), while the peak systolic pressure derived from CFD (PSP_CFD) was compared to catheterization (PSP_CC). Regions with low and high peak systolic wall shear stress (PSWSS) were also evaluated.

Results

PSV_CFD and PSP_CFD showed good agreements between PSV_TTE (r = 0.968, p < 0.001; mean bias = − 7.68 cm/s) and PSP_CC (r = 0.918, p < 0.001; mean bias = 1.405 mmHg). Regions with low and high PSWSS) can also be visualized. Skewing of velocity or helical blood flow was also observed at aortic arch in patients.

Conclusions

Our result demonstrated that CFD scheme based on MDCTA raw data is an accurate and convenient method in obtaining the velocity and pressure from aorta and displaying the distribution of PSWSS and flow pattern of aorta. The preliminary results from our study demonstrate the capability in combining clinical imaging data and novel CFD tools in infants with CHD and provide a noninvasive approach for diagnose of CHD such as coarctation of aorta in future.

Contemporary endovascular treatment of type B aortic dissection in China

OBJECTIVE

Endovascular stent-grafts have been used in China to treat type B aortic dissection since 1999, and there is a plethora of cohort studies in the contemporary literature. The aim of this review was to analyse the published results of endovascular treatment for type B aortic dissection in China.

METHOD

A systematic literature review of all published literature from January 1999 to October 2014 on endovascular treatment of type B aortic dissection in China was undertaken using PubMed, Medline, and the Chinese National Knowledge Infrastructure databases.

RESULTS

Seventy papers were retrieved (4 English, 66 Chinese) with a total of 4208 patients; 3396 (80.7%) were male, and the mean age ranged from 43 to 65 years. Procedural success was reported in 99.4% ± 1.7%. Complications were reported in 14.6% ± 11.1%, with major complications in 1.7% ± 2.9%, and the most devastating neurologic complications in 1.1% ± 2.2% (stroke 0.9% ± 2.4%, paraplegia 1.5% ± 0.7%). Postoperative endoleak occurred in 8.1% ± 7.6%. The 30-day postoperative mortality was 2.4% ± 3.3%. During follow-up, false-lumen thrombosis occurred in 92.1% ± 11.7%. Reintervention was performed in 1.3% ± 3.3%. The incidence of proximal and distal stent-graft-induced new entry was 0.5% ± 1.3% and 0.9% ± 2.7%, respectively, with endoleak in 2.7% ± 4.4% and mortality of 2.2% ± 3.2%.

CONCLUSIONS

Current evidence suggests that use of endovascular stent-grafts for type B aortic dissection in China is feasible and safe with low rates of perioperative complications and short-term mortality. However, a standardised reporting system and long-term follow-up data are lacking.

Aortic dissection simulation models for clinical support: fluid-structure interaction vs. rigid wall models

BACKGROUND

The management and prognosis of aortic dissection (AD) is often challenging and the use of personalised computational models is being explored as a tool to improve clinical outcome. Including vessel wall motion in such simulations can provide more realistic and potentially accurate results, but requires significant additional computational resources, as well as expertise. With clinical translation as the final aim, trade-offs between complexity, speed and accuracy are inevitable. The present study explores whether modelling wall motion is worth the additional expense in the case of AD, by carrying out fluid-structure interaction (FSI) simulations based on a sample patient case.

METHODS

Patient-specific anatomical details were extracted from computed tomography images to provide the fluid domain, from which the vessel wall was extrapolated. Two-way fluid-structure interaction simulations were performed, with coupled Windkessel boundary conditions and hyperelastic wall properties. The blood was modelled using the Carreau-Yasuda viscosity model and turbulence was accounted for via a shear stress transport model. A simulation without wall motion (rigid wall) was carried out for comparison purposes.

RESULTS

The displacement of the vessel wall was comparable to reports from imaging studies in terms of intimal flap motion and contraction of the true lumen. Analysis of the haemodynamics around the proximal and distal false lumen in the FSI model showed complex flow structures caused by the expansion and contraction of the vessel wall. These flow patterns led to significantly different predictions of wall shear stress, particularly its oscillatory component, which were not captured by the rigid wall model.

CONCLUSIONS

Through comparison with imaging data, the results of the present study indicate that the fluid-structure interaction methodology employed herein is appropriate for simulations of aortic dissection. Regions of high wall shear stress were not significantly altered by the wall motion, however, certain collocated regions of low and oscillatory wall shear stress which may be critical for disease progression were only identified in the FSI simulation. We conclude that, if patient-tailored simulations of aortic dissection are to be used as an interventional planning tool, then the additional complexity, expertise and computational expense required to model wall motion is indeed justified.

The role of multidetector-row CT in the diagnosis, classification and management of acute aortic syndrome

The term "acute aortic syndrome" (AAS) encompasses several non-traumatic life-threatening pathologies of the thoracic aorta presenting in patients with a similar clinical profile. These include aortic dissection, intramural haematoma and penetrating atherosclerotic ulcers. These different pathological entities can be indistinguishable on clinical grounds alone and may be confused with other causes of chest pain, including myocardial infarction. Multidetector-row CT (MDCT) is the current modality of choice for imaging AAS with a sensitivity and specificity approaching 100%. Early diagnosis and accurate radiological classification is associated with improved clinical outcomes in AAS. We review the characteristic radiological features of the different pathologies that encompass AAS and highlight the vital role of MDCT in determining the management of these life-threatening conditions.

Endovascular repair of acute uncomplicated aortic type B dissection promotes aortic remodelling: 1 year results of the ADSORB trial

OBJECTIVES

Uncomplicated acute type B aortic dissection (AD) treated conservatively has a 10% 30-day mortality and up to 25% need intervention within 4 years. In complicated AD, stent grafts have been encouraging. The aim of the present prospective randomised trial was to compare best medical treatment (BMT) with BMT and Gore TAG stent graft in patients with uncomplicated AD. The primary endpoint was a combination of incomplete/no false lumen thrombosis, aortic dilatation, or aortic rupture at 1 year.

METHODS

The AD history had to be less than 14 days, and exclusion criteria were rupture, impending rupture, malperfusion. Of the 61 patients randomised, 80% were DeBakey type IIIB.

RESULTS

Thirty-one patients were randomised to the BMT group and 30 to the BMT+TAG group. Mean age was 63 years for both groups. The left subclavian artery was completely covered in 47% and in part in 17% of the cases. During the first 30 days, no deaths occurred in either group, but there were three crossovers from the BMT to the BMT+TAG group, all due to progression of disease within 1 week. There were two withdrawals from the BMT+TAG group. At the 1-year follow up there had been another two failures in the BMT group: one malperfusion and one aneurysm formation (p = .056 for all). One death occurred in the BMT+TAG group. For the overall endpoint BMT+TAG was significantly different from BMT only (p < .001). Incomplete false lumen thrombosis, was found in 13 (43%) of the TAG+BMT group and 30 (97%) of the BMT group (p < .001). The false lumen reduced in size in the BMT+TAG group (p < .001) whereas in the BMT group it increased. The true lumen increased in the BMT+TAG (p < .001) whereas in the BMT group it remained unchanged. The overall transverse diameter was the same at the beginning and after 1 year in the BMT group (42.1 mm), but in the BMT+TAG it decreased (38.8 mm; p = .062).

CONCLUSIONS

Uncomplicated AD can be safely treated with the Gore TAG device. Remodelling with thrombosis of the false lumen and reduction of its diameter is induced by the stent graft, but long term results are needed.

Evaluation of the hemodynamic effectiveness of aortic dissection treatments via virtual stenting

Aortic dissection treatment varies for each patient and stenting is one of a number of approaches that are utilized to Stabilize the condition. Information regarding the hemodynamic forces in the aorta in dissected and virtually stented cases could support clinicians in their choices of treatment prior to medical intervention. Computational fluid dynamics coupled with lumped parameter models have shown promise in providing detailed information that could be used in the clinic; for this, it is necessary to develop personalized workflows in order to produce patient-specific simulations. In the present study, a case of pre- and post-stenting (virtual stent-graft) of an aortic dissection is investigated with a particular focus on the role of personalized boundary conditions. For each virtual case, velocity, pressure, energy loss, and wall shear stress values are evaluated and compared. The simulated single stent-graft only marginally reduced the pulse pressure and systemic energy loss. The double stent-graft results showed a larger reduction in pulse pressure and a 40% reduction in energy loss as well as a more physiological wall shear stress distribution.Regions of potential risk were highlighted. The methodology applied in the present study revealed detailed information about two possible surgical outcome cases and shows promise as both a diagnostic and an interventional tool.

A patient-specific study of type-B aortic dissection: evaluation of true-false lumen blood exchange

Background

Aortic dissection is a severe pathological condition in which blood penetrates between layers of the aortic wall and creates a duplicate channel – the false lumen. This considerable change on the aortic morphology alters hemodynamic features dramatically and, in the case of rupture, induces markedly high rates of morbidity and mortality.

Methods

In this study, we establish a patient-specific computational model and simulate the pulsatile blood flow within the dissected aorta. The k-ω SST turbulence model is employed to represent the flow and finite volume method is applied for numerical solutions. Our emphasis is on flow exchange between true and false lumen during the cardiac cycle and on quantifying the flow across specific passages. Loading distributions including pressure and wall shear stress have also been investigated and results of direct simulations are compared with solutions employing appropriate turbulence models.

Results

Our results indicate that (i) high velocities occur at the periphery of the entries; (ii) for the case studied, approximately 40% of the blood flow passes the false lumen during a heartbeat cycle; (iii) higher pressures are found at the outer wall of the dissection, which may induce further dilation of the pseudo-lumen; (iv) highest wall shear stresses occur around the entries, perhaps indicating the vulnerability of this region to further splitting; and (v) laminar simulations with adequately fine mesh resolutions, especially refined near the walls, can capture similar flow patterns to the (coarser mesh) turbulent results, although the absolute magnitudes computed are in general smaller.

Conclusions

The patient-specific model of aortic dissection provides detailed flow information of blood transport within the true and false lumen and quantifies the loading distributions over the aorta and dissection walls. This contributes to evaluating potential thrombotic behavior in the false lumen and is pivotal in guiding endovascular intervention. Moreover, as a computational study, mesh requirements to successfully evaluate the hemodynamic parameters have been proposed.

A longitudinal study of Type-B aortic dissection and endovascular repair scenarios: computational analyses

Conservative medical treatment is commonly first recommended for patients with uncomplicated Type-B aortic dissection (AD). However, if dissection-related complications occur, endovascular repair or open surgery is performed. Here we establish computational models of AD based on radiological three-dimensional images of a patient at initial presentation and after 4-years of best medical treatment (BMT). Computational fluid dynamics analyses are performed to quantitatively investigate the hemodynamic features of AD. Entry and re-entries (functioning as entries and outlets) are identified in the initial and follow-up models, and obvious variations of the inter-luminal flow exchange are revealed. Computational studies indicate that the reduction of blood pressure in BMT patients lowers pressure and wall shear stress in the thoracic aorta in general, and flattens the pressure distribution on the outer wall of the dissection, potentially reducing the progressive enlargement of the false lumen. Finally, scenario studies of endovascular aortic repair are conducted. The results indicate that, for patients with multiple tears, stent-grafts occluding all re-entries would be required to effectively reduce inter-luminal blood communication and thus induce thrombosis in the false lumen. This implicates that computational flow analyses may identify entries and relevant re-entries between true and false lumen and potentially assist in stent-graft planning.

Aortic branch artery pseudoaneurysms associated with intramural hematoma: when and how to do endovascular embolization

PURPOSE

To describe when and how to perform endovascular embolization of aortic branch artery pseudoaneurysms associated with type A and type B intramural hematoma (IMH) involving the descending thoracic and abdominal aorta (DeBakey I and III) that increased significantly in size during follow-up.

MATERIALS AND METHODS

Sixty-one patients (39 men; mean ± standard deviation age 66.1 ± 11.2 years) with acute IMH undergoing at least two multidetector computed tomographic examinations during follow-up for 12 months or longer were enrolled. Overall, 48 patients (31 men, age 65.9 ± 11.5) had type A and type B IMH involving the descending thoracic and abdominal aorta (DeBakey I and III).

RESULTS

Among the 48 patients, 26 (54 %; 17 men, aged 64.3 ± 11.4 years) had 71 aortic branch artery pseudoaneurysms. Overall, during a mean follow-up of 22.1 ± 9.5 months (range 12-42 months), 31 (44 %) pseudoaneurysms disappeared; 22 (31 %) decreased in size; two (3 %) remained stable; and 16 (22 %) increased in size. Among the 16 pseudoaneurysms with increasing size, five of these (three intercostal arteries, one combined intercostobronchial/intercostal arteries, one renal artery), present in five symptomatic patients, had a significant increase in size (thickness >10 mm; width and length >20 mm). These five patients underwent endovascular embolization with coils and/or Amplatzer Vascular Plug. In all patients, complete thrombosis and exclusion of aortic pseudoaneurysm and relief of back pain were achieved.

CONCLUSION

Aortic branch artery pseudoaneurysms associated with type A and type B IMH involving the descending thoracic and abdominal aorta (DeBakey I and III) may be considered relatively benign lesions. However, a small number may grow in size or extend longitudinally with clinical symptoms during follow-up, and in these cases, endovascular embolization can be an effective and safe procedure.