The Impact of Intimal Tear Location and Partial False Lumen Thrombosis in Acute Type B Aortic Dissection

Radiographic complicated and uncomplicated descending aortic dissections: aortic morphological differences by CT angiography and risk factor analysis

AIMS

To identify radiographic differences between patients with uncomplicated and complicated descending aortic dissections.

METHODS AND RESULTS

Between April 2009 and July 2021, 209 patients with acute descending aortic dissections were analysed as complicated (malperfusion, rupture, diameter progress, and diameter ≥ 55 mm) or uncomplicated. Detailed CTA measurements (slice thickness ≤ 3 mm) were taken in multiplanar reconstruction. A composite endpoint (early aortic failure) was defined as reoperation, diameter progression, and early mortality. Seventy-seven patients were female (36.8%) [complicated n = 27 (36.5%); uncomplicated n = 50 (37.0%) P = 1.00]. Seventy-four (35%) patients were categorized as morphologically complicated, and 135 (65%) as uncomplicated. In patients with complicated dissections, the dissection extended more frequently to the aortic bifurcation (P = 0.044), the coeliac trunk (P = 0.003), the superior mesenteric artery (P = 0.007), and both iliac arteries (P < 0.001) originated less frequently from the true lumen. The length of the most proximal communication (entry) in type B aortic dissection was longer, 14.0 mm [12.0 mm; 27.0 mm] vs. 6.0 mm [4,0 mm; 13.0 mm] in complicated cases (P = 0.005). Identified risk factors for adverse aortic events were connective tissue disease [HR 8.0 (1.9-33.7 95% CI HR)], length of the aortic arch [HR 4.7 (1.5-15.1 95% CI HR)], a false lumen diameter > 19.38 mm [HR 3.389 (1.1-10.2 95% CI HR)], and origin of the inferior mesenteric artery from the false lumen [HR 4.2 (1.0-5.5 95% CI HR)].

CONCLUSION

We identified significant morphological differences and predictors for adverse events in patients presenting complicated and uncomplicated descending dissections. Our morphological findings will help guide future aortic therapies, taking a tailored patient approach.

The Role of Multiple Re-Entry Tears in Type B Aortic Dissection Progression: A Longitudinal Study Using a Controlled Swine Model

PURPOSE

False lumen (FL) expansion often occurs in type B aortic dissection (TBAD) and has been associated with the presence of re-entry tears. This longitudinal study aims to elucidate the role of re-entry tears in the progression of TBAD using a controlled swine model, by assessing aortic hemodynamics through combined imaging and computational modeling.

MATERIALS AND METHODS

A TBAD swine model with a primary entry tear at 7 cm distal to the left subclavian artery was created in a previous study. In the current study, reintervention was carried out in this swine model to induce 2 additional re-entry tears of approximately 5 mm in diameter. Computed tomography (CT) and 4-dimensional (4D) flow magnetic resonance imaging (MRI) scans were taken at multiple follow-ups before and after reintervention. Changes in aortic volume were measured on CT scans, and hemodynamic parameters were evaluated based on dynamic data acquired with 4D-flow MRI and computational fluid dynamics simulations incorporating all available in vivo data.

RESULTS

Morphological analysis showed FL growth of 20% following the initial TBAD-growth stabilized after the creation of additional tears and eventually FL volume reduced by 6%. Increasing the number of re-entry tears from 1 to 2 caused flow redistribution, with the percentage of true lumen (TL) flow increasing from 56% to 78%; altered local velocities; reduced wall shear stress surrounding the tears; and led to a reduction in FL pressure and pressure difference between the 2 lumina.

CONCLUSION

This study combined extensive in vivo imaging data with sophisticated computational methods to show that additional re-entry tears can alter dissection hemodynamics through redistribution of flow between the TL and FL. This helps to reduce FL pressure, which could potentially stabilize aortic growth and lead to reversal of FL expansion. This work provides a starting point for further study into the use of fenestration in controlling undesirable FL expansion.

CLINICAL IMPACT

Aortic growth and false lumen (FL) patency are associated with the presence of re-entry tears in type B aortic dissection (TBAD) patients. Guidelines on how to treat re-entry tears are lacking, especially with regards to the control and prevention of FL expansion. Through a combined imagining and computational hemodynamics study of a controlled swine model, we found that increasing the number of re-entry tears reduced FL pressure and cross lumen pressure difference, potentially stabilising aortic growth and leading to FL reduction. Our findings provide a starting point for further study into the use of fenestration in controlling undesirable FL expansion.

The Role of Location, Length, and Thickness of the Intimal Flap in the Propagation of Stanford Type B Aortic Dissection Based on Ex Vivo Porcine Aorta Models

PURPOSE

To explore the role of location, length, and thickness of the intimal flap in the propagation of Stanford type B aortic dissection (TBAD) based on ex vivo porcine aorta models based on ex vivo porcine aorta models.

MATERIALS AND METHODS

The porcine aortas were harvested and randomly divided into 6 groups to create various TBAD aortic models. We constructed intimal flaps for different locations (group A [entry tear on outer curvature] and group B [entry tear on inner curvature]), lengths (group C [long] and group D [short]), and thicknesses (group E [thick] and group F [thin]). For the ex vivo perfusion experiments conducted on model aortas, an experimental circulation loop (ECL) was employed. The pressure in false lumen (FL) was constantly monitored. A comparison was made between the morphological data collected before and after the experiment to quantify the changes in the FL after the experiment.

RESULTS

Compared the results with group B, the mean peak pressures of the FL in group A were lower (106.87±15.55 vs. 124.01±22.75 mm Hg, p=0.028). The mean axial propagation length in group A was shown to be shorter than that of group B (88.14±33.38 vs. 197.43±41.65 mm, p<0.001). The mean peak pressure was higher in group C than in group D (144.04±19.37 vs. 92.51±26.70 mm Hg, p<0.001). The mean peak pressure of group E was higher than that of group F (160.83±32.83 vs. 109.33±15.62 mm Hg, p<0.001), as was the mean axial propagation length of group E (143.11±39.73 vs. 100.45±35.44 mm, p=0.021). According to the results of multivariable linear regression, axial propagation length=45.873-0.703×length of initial FL+0.863× peak pressure (p<0.001).

CONCLUSION

There was a relationship between FL propagation and the location, length, and thickness of the intimal flap. The axial propagation length was related to the length of the intimal flap and the peak pressure of propagation. It may be helpful to evaluate the risk of propagation in patients with TBAD.

CLINICAL IMPACT

This study found that the locations, lengths, and thickness of the intimal flap significantly contributed to propagation pressure of FL. Using dissection flap characteristics, a physician can predict FL development in a patient and formulate a treatment plan.The purpose was to investigate the relationship between the dissection flap characteristics (location, length, and thickness) and the propagation of the FL, which is not clear at present. This study employed porcine models to create an experimental circulation loop. The perfusion experiment was conducted using a FL without distal re-entry and a non-pulsating flow.

Model-Based Fluid-Structure Interaction Approach for Evaluation of Thoracic Endovascular Aortic Repair Endograft Length in Type B Aortic Dissection

Thoracic endovascular aortic repair (TEVAR) is a commonly performed operation for patients with type B aortic dissection (TBAD). The goal of TEVAR is to cover the proximal entry tear between the true lumen (TL) and the false lumen (FL) with an endograft to induce FL thrombosis, allow for aortic healing, and decrease the risk of aortic aneurysm and rupture. While TEVAR has shown promising outcomes, it can also result in devastating complications including stroke, spinal cord ischemia resulting in paralysis, as well as long-term heart failure, so treatment remains controversial. Similarly, the biomechanical impact of aortic endograft implantation and the hemodynamic impact of endograft design parameters such as length are not well-understood. In this study, a fluid-structure interaction (FSI) computational fluid dynamics (CFD) approach was used based on the immersed boundary and Lattice–Boltzmann method to investigate the association between the endograft length and hemodynamic variables inside the TL and FL. The physiological accuracy of the model was evaluated by comparing simulation results with the true pressure waveform measurements taken during a live TEVAR operation for TBAD. The results demonstrate a non-linear trend towards increased FL flow reversal as the endograft length increases but also increased left ventricular pulsatile workload. These findings suggest a medium-length endograft may be optimal by achieving FL flow reversal and thus FL thrombosis, while minimizing the extra load on the left ventricle. These results also verify that a reduction in heart rate with medical therapy contributes favorably to FL flow reversal.

Ratio of the false lumen to the true lumen is associated with long-term prognosis after surgical repair of acute type A aortic dissection

Objectives

The aim of this study was to assess potential predictors of aortic events after an emergency surgery for acute type A aortic dissection, especially paying attention to the findings of computed tomography (CT) performed immediately after the surgery.

Methods

Between January 2001 and December 2015, 72 patients, who were diagnosed as having Stanford type A acute aortic dissection with a patent false lumen in the descending thoracic aorta, survived the emergency operation, and had postoperative CT scan data, were included in this study (mean follow-up, 8.2 ± 3.8 years; range 0.8-17.4 years). From the CT scan data, the diameter of the false lumen (FL-D) and true lumen (TL-D) were measured, and the FL-D:TL-D ratio was calculated. Long-term outcomes of the FL-D > TL-D group (n = 30) and the FL-D < TL-D group (n = 42) were compared.

Results

In the late follow-up, 17 aortic events in the downstream aorta were observed. The FL-D:TL-D ratio (P = .01) was an adjusted risk of aortic events in multivariable analysis. The rates of freedom from aortic events at 5 and 9 years were superior in the FL-D < TL-D group than in the FL-D > TL-D group (92.0% and 88.6% vs 81% and 60.7%; log rank P < .05).

Conclusions

Our results suggest that the false lumen:true lumen ratio predicts long-term prognosis after surgical repair of acute type A aortic dissection.

An in vitro Assessment of the Haemodynamic Features Occurring Within the True and False Lumens Separated by a Dissection Flap for a Patient-Specific Type B Aortic Dissection

One of the highest mortality rates of cardiovascular diseases is aortic dissections with challenging treatment options. Currently, less study has been conducted in developing in vitro patient-specific Type B aortic dissection models, which mimic physiological flow conditions along the true and false lumens separated by a dissection flap with multiple entry and exit tears. A patient-specific Stanford Type B aortic dissection scan was replicated by an in-house manufactured automatic injection moulding system and a novel modelling technique for creating the ascending aorta, aortic arch, and descending aorta incorporating arterial branching, the true/false lumens, and dissection flap with entry and exit intimal tears. The physiological flowrates and pressure values were monitored, which identified jet stream fluid flows entering and exiting the dissection tears. Pressure in the aorta’s true lumen region was controlled at 125/85 mmHg for systolic and diastolic values. Pressure values were obtained in eight sections along the false lumen using a pressure transducer. The true lumen systolic pressure varied from 122 to 128 mmHg along the length. Flow patterns were monitored by ultrasound along 12 sections. Detailed images obtained from the ultrasound transducer probe showed varied flow patterns with one or multiple jet steam vortices along the aorta model. The dissection flap movement was assessed at four sections of the patient-specific aorta model. The displacement values of the flap varied from 0.5 to 3 mm along the model. This model provides a unique insight into aortic dissection flow patterns and pressure distributions. This dissection phantom model can be used to assess various treatment options based on the surgical, endovascular, or hybrid techniques.

Outer Media Thickness at False Lumen and Secondary Aortic Dilatation After Acute Aortic Dissection

BACKGROUND

This study measured the outer media thickness (OMT) at the false lumen by using microscopic images of specimens collected intraoperatively and assessed the impact of OMT on secondary dilatation of the downstream aorta.

METHODS

Of 238 patients undergoing surgical procedures for acute type A dissection between 2007 and 2016, 129 patients fulfilled the inclusion criteria for this study: DeBakey type I dissection with a patent false lumen, histopathologic examination of full-thickness aortic wall, and at least 1 follow-up computed tomographic scan at more than 3 months after surgical procedures. On average, 5.1 scans were obtained per patient, and median follow-up was 4.3 years.

RESULTS

Considerable variation was observed in OMT (median, 0.21 mm; range, 0.04-0.51 mm). The aortic diameter growth rate was inversely correlated with the OMT, and in the lowest tertile of OMT the aortic diameter dilated significantly faster in the first year than later and faster than in the other tertiles. Multivariable Fine-Gray analysis, with death as the competing risk, identified OMT as an independent variable for aortic-related events. Patients with OMT of 0.04 to 0.15 mm had a 3.54-fold higher risk of aortic-related events and those with 0.16 to 0.31 mm had a 1.56-fold higher risk of aortic-related events than did patients with OMT of 0.32 to 0.51 mm. Multivariable Cox regression analyses revealed OMT of 0.04 to 0.15 mm as an independent variable for all-cause mortality.

CONCLUSIONS

In patients with DeBakey type I aortic dissection with a patent false lumen, the growth rate of the distal residual dissecting aorta was inversely correlated with the OMT. The risk of aortic-related events was significantly higher in patients with OMT of 0.04 to 0.15 mm.

Hemodynamic Study of Stanford Type B Aortic Dissection Based on Ex Vivo Porcine Aorta Models

Background:

In this study, we aimed to evaluate hemodynamic influence of the dissected aortic system via various ex vivo type B aortic dissection (AD) models.

Methods:

Twenty-four raw porcine aortas were harvested and randomly divided into 4 groups to create various aortic models. Model A was the control group, while models B to D indicated the AD group, where models B and C presented a proximal primary entry with the false lumen (FL) lengths of 15 and 20 cm, respectively, and model D presented a 20 cm FL with a proximal primary entry and a distal reentry. All the aortic models were connected to a mock circulation loop to attain the realistic flow and pressure status. The flow distribution rate (FDR) of the aortic branches was calculated. Doppler ultrasound was applied to visualize the AD structure and to attain the velocity of flow in both the true and false lumens. Several sections of the AD were stained with hematoxylin and eosin for histologic evaluation after the experiment.

Results:

This study demonstrated that higher pressures were found for the AD group compared with the control group. The mean systolic pressures at the inlet of models A to D were 113.34±0.81, 120.58±0.52, 117.76±0.82, and 115.87±0.42 mm Hg, respectively. The FDRs of the celiac artery in models A to D were 8.65%, 8.32%±0.15%, 7.87%±0.13%, and 8.03%±0.21%, respectively. By ultrasound visualization, the velocity of the flow at the entry to the FL in the AD group ranged in 10 to 92 cm/s. The dissection flap presented pulsatile movement, especially in the models B and C which contained 1 primary entry without distal reentries. Histological examinations indicated that AD was located between the intimal and medial layers.

Conclusions:

Our ex vivo models demonstrated that the configuration of the dissected aorta influenced the pressure distribution. Moreover, the dissection flap affected the FDR of the aortic branches that possibly inducing malperfusion syndrome.

Experimental evaluation of the patient-specific haemodynamics of an aortic dissection model using particle image velocimetry

Aortic Dissection (AD) is a complex pathology that affects the aorta. Diagnosis, management and treatment remain a challenge as it is a highly patient-specific pathology and there is still a limited understanding of the fluid-mechanics phenomena underlying clinical outcomes. Although in vitro models can allow the accurate study of AD flow fields in physical phantoms, they are currently scarce and almost exclusively rely on over simplifying assumptions. In this work, we present the first experimental study of a patient-specific case of AD. An anatomically correct phantom was produced and combined with a state-of-the-art in vitro platform, informed by clinical data, employed to accurately reproduce personalised conditions. The complex AD haemodynamics reproduced by the platform was characterised by flow rate and pressure acquisitions as well as Particle Image Velocimetry (PIV) derived velocity fields. Clinically relevant haemodynamic indices, that can be correlated with AD prognosis - such as velocity, shear rate, turbulent kinetic energy distributions - were extracted in two regions of interest in the aortic domain. The acquired data highlighted the complex nature of the flow (e.g. recirculation regions, low shear rate in the false lumen) and was in very good agreement with the available clinical data and the CFD results of a study conducted alongside, demonstrating the accuracy of the findings. These results demonstrate that the described platform constitutes a powerful, unique tool to reproduce in vitro personalised haemodynamic conditions, which can be used to support the evaluation of surgical procedures, medical devices testing and to validate state-of-the-art numerical models.

A meta-analysis of combined proximal stent grafting with or without adjunctive distal bare stent for the management of aortic dissection

BACKGROUND

The efficacy and safety of placement of a proximal covered stent graft combined with a distal bare stent are controversial because of the lack of evidence. This systematic review and meta-analysis compared the outcomes of combined proximal covered stent grafting with distal bare stenting (BS group) and proximal covered stent grafting without distal bare stenting (non-BS group).

METHODS

The MEDLINE, Embase, and Cochrane Central Register of Controlled Trials databases and key references were searched up to January 26, 2019. Predefined outcomes of interest were mortality, morbidity, and postoperative assessment of aortic remodeling. We pooled risk ratios (RRs) of the outcomes of interest using fixed effects model or random effects model.

RESULTS

Overall, eight observational studies involving 914 patients were included. There were no significant differences in overall aorta-related mortality (RR, 0.54; confidence interval [CI], 0.24-1.24; P = .15), complete thoracic false lumen (FL) thrombosis rate (RR, 1.23; CI, 0.83-1.81; P = .30), or complete abdominal FL thrombosis rate (RR, 1.96; CI, 0.68-5.69; P = .21) between the BS group and the non-BS group. The BS group had a lower rate of partial thoracic FL thrombosis (RR, 0.40; CI, 0.25-0.65; P = .0002), a lower stent graft-induced new entry rate (RR, 0.08; CI, 0.02-0.41; P = .003), and a lower reintervention rate (RR, 0.42; CI, 0.26-0.69; P = .0005).

CONCLUSIONS

Combined proximal covered stent grafting with distal adjunctive bare stenting had the potential to reduce the partial thoracic FL thrombosis rate and the rates of stent graft-induced new entry and reintervention but was not associated with lower aorta-related mortality or the complete FL thrombosis rate. Further research with a stricter methodology is needed.

Midterm prognosis of type B aortic dissection with and without dissecting aneurysm of descending thoracic aorta after endovascular repair

Few studies support guidelines for the use of thoracic endovascular aortic repair (TEVAR) to address type B aortic dissection (TBAD) coexisting with descending thoracic aortic dissection and aneurysm (dTADA). This cohort study investigated midterm outcomes of TBAD with dTADA (dTADA group, n = 31) and without dTADA (non-dTADA group, n = 98) after TEVAR. Compared with the non-dTADA group, the dTADA group exhibited higher incidences of type Ia endoleak (29.0% vs. 3.1%, P < 0.001) and reintervention (16.1% vs. 5.1%, P = 0.045). The completely thrombosed rate of the thoracic false lumen was significantly lower in the dTADA group than in the non-dTADA group (45.2% vs. 80.6%, P < 0.001). Although the two groups exhibited similar mortality rates, TBAD coexisting with no regressive dTADA after TEVAR was an independent predictor of mortality (HR: 15.52, 95% CI: 1.614-149.233, P = 0.018). Moreover, the change percentages of false lumen retraction and true lumen re-expansion in the dTADA group were significantly inferior to those of the non-dTADA group at levels of 4th, 6th, 8th and 10th thoracic vertebra throughout follow-up. In conclusion, in the presence of preexisting dTADA, the failure of the dTADA to regress after TEVAR is associated with lower survival and a higher risk of reintervention.

Locational impact of luminal communication on aortic diameter changes and reintervention in acute type I aortic dissection

OBJECTIVES

The aim of this study is to evaluate the locational impact of a luminal communication on aortic diameter changes and reintervention after surgical repair of acute type I aortic dissection.

METHODS

Between 2009 and 2017, 304 patients underwent operation for acute type I aortic dissection. Among them, 93 patients were enrolled. The luminal communications were analysed in segment 1 (the proximal descending thoracic aorta), segment 2 (the distal descending thoracic aorta) and segment 3 (the abdominal aorta). The aortic diameter was measured at the pulmonary artery bifurcation, coeliac axis, maximal abdominal aorta and maximal thoraco-abdominal aorta using serial follow-up computed tomography scans. The linear mixed model was used, and the rate of freedom from reintervention was analysed.

RESULTS

In the adjusted analysis, the initial diameter of the maximal abdominal aorta and the first luminal communication in segment 1 was statistically significant. However, the slope value of the maximal abdominal aorta was smaller than that of the first luminal communication in segment 1 (0.024 vs 0.198). The 3-year freedom from reintervention rate was significantly higher in patients without a luminal communication than in those with an initial luminal communication in segment 1 (96% vs 47%, log rank, P = 0.003).

CONCLUSIONS

A luminal communication at the proximal descending thoracic aorta (segment 1) is a significant factor for an increasing aortic diameter and reintervention after surgical repair of acute type I aortic dissection.

Proposed classification of endoleaks after endovascular treatment of Stanford type-B aortic dissections

Objectives

Despite two decades of experience, no dedicated classification system exists to document and prognosticate patterns of endoleak encountered after endovascular therapy of type-B aortic dissection. This nomenclature gap has led to inconsistent management and underreporting of significant findings associated with adverse outcomes after endovascular treatment of type-B aortic dissection. Our goal was to propose a reproducible and prognostically relevant classification.

Methods

A multidisciplinary team of seven experienced open and endovascular aortic surgeons was assembled to provide consensus opinion. Extensive literature review was conducted. Deficiencies in the current classification approach of the various patterns of persistent filling of false lumen after endovascular therapy were identified.

Results

Our focus was to categorize high-risk and low-risk subgroups within endoleaks after endovascular treatment of type-B aortic dissection. In this classification, type-Ia endoleak refers to persistent filling of the false lumen in an antegrade manner. Causes include failure to cover the primary entry tear and sizing or technical related proximal seal failure. False lumen filling via distal entry tears is classified as type Ib endoleak, which is further sub-classified into b1 (major branch-related tears), and b2 (multiple small branches related tears). Retrograde ascending aortic dissection and stent graft-induced new entry were classified as type-I endoleaks (type-Ir and type-Is, respectively). Another focus was reclassification type-II endoleaks, with type-IIa endoleak referring to conventional retroleak from one or more posterior branches and type-IIx referring to retroleak from major branches (visceral or left subclavian arteries).

Conclusions

The majority of endoleaks after endovascular treatment of type-B aortic dissection are related to persistent or new filling of the false lumen. We propose a new false lumen-based classification schema for endoleaks occurring after endovascular therapy of type-B aortic dissection.

Morphological predictor of remodelling of the descending thoracic aortic false lumen that remains patent after repair of acute type A dissection

OBJECTIVES

Some patients achieve complete recovery through false lumen remodelling in the descending aorta after surgery for acute type A aortic dissection. Our goal was to investigate the relationship between false lumen remodelling during later postoperative stages and quantitative analysis of the true lumen shape during the early postoperative stages.

METHODS

We examined 88 surgical patients between January 2007 and December 2016. Three points of the descending aorta were assessed from the 6th (T6), the 9th (T9) and the 11th (T11) vertebral levels. The shape of the true lumen was evaluated during the early postoperative stages, and false lumen remodelling 1 year after surgery was the end point. The parameters obtained by evaluating the shape of the true lumen comprised the first principal component analysis using elliptic Fourier analysis, the minor diameter ratio and the ratio of the area of the true lumen to that of the descending aorta, and the number of contact points on the true lumen wall during the early stages.

RESULTS

Using univariate analysis, we detected significant differences in the first principal components, the minor diameter ratio, the area ratio and the number of contact points at each thoracic vertebral level (P < 0.05). The cut-off value of the minor diameter ratio was 0.55, and the area ratio was 0.48 as determined by analysis of the receiver operating characteristic. Multivariable logistic analysis indicated that the first principal component was the most significant predictor from the proximal to the middle descending aorta.

CONCLUSIONS

Quantitative evaluation of shape of the true lumen in the early postoperative stages after surgery for acute type A dissection can serve as a viable predictor for false lumen remodelling in later stages. Furthermore, the first principal component could serve as a more astute predictor than other quantitative parameters according to multivariate analysis.

A Promising Treatment of Distal Entry Tears Located in Branched Area of Abdominal Aorta With Coil-Stent Tear Occlusion Device: an Animal Experiment

This study aims to evaluate the effect of coil-stent tear occlusion device in treating entry tears located in branched area of abdominal aorta. An abdominal aortic dissection animal model was constructed by mesh suturing method. The animal models were treated by the occlusion device and were evaluated by computed tomography angiography (CTA) 1 month later. Eighteen pigs were adopted in the abdominal aortic dissection modeling experiment, two of them died of cardiopulmonary arrest during the operation. Sixteen models survived, two of them were found complete false lumen thrombosis by CTA 3 days after the operation. The false lumen kept patency in the remaining 14 cases which were then implanted with the occlusion device. The procedure was successful in 13 cases except for one. The coil-stent tear occlusion device provides a novel method for tears located in the branched area of abdominal aorta, and is worth of further study.

Predictors of Failure of Medical Management in Uncomplicated Type B Aortic Dissection

BACKGROUND

Optimal medical therapy (OMT) for uncomplicated type B aortic dissection (uTBAD) provides excellent short-term outcomes but is associated with a high incidence of failure. This study identified predictors of aortic intervention and mortality in uTBAD patients undergoing OMT.

METHODS

A retrospective review of the Emory University School of Medicine aortic database identified 314 uTBAD patients undergoing OMT from 2000 to 2016. Two hundred sixty-three (84%) patients had imaging at presentation analyzed for maximum aortic diameters (ADs), false lumen (FL) status, and visceral vessel perfusion. Cox proportional hazards models were constructed to estimate hazards ratios (HRs) and identify predictors of OMT failure.

RESULTS

The mean age of patients was 58 ± 12 years, and 67% were men. FL status was patent in 59.4%, partially thrombosed in 39.8%, and completely thrombosed in 0.8% of patients. Over a median follow-up of 5.6 (interquartile range, 1.4 to 8.5) years, 44.9% of patients failed OMT and underwent intervention (n = 58 open, n = 83 endovascular). The estimated incidence of OMT failure was 46%. Multivariate analysis identified the presence of diabetes, renal failure, DeBakey 3B dissection, and a descending thoracic AD of 4.5 cm or greater (HR, 1.39; 95% confidence interval, 1.24 to 1.56; p < 0.001) to be independent predictors of failure of OMT. FL status or the distribution of visceral vessels arising from the FL did not predict OMT failure.

CONCLUSIONS

There is a significant incidence of OMT failure in uTBAD patients. A descending thoracic AD of 4.5 cm or greater at the time of diagnosis is an independent predictor of failure of OMT.

Differential impact of intimal tear location on aortic dilation and reintervention in acute type I aortic dissection after total arch replacement

OBJECTIVE

The study objective was to evaluate the differential impact of intimal tear location on aortic dilation and reintervention after total arch replacement for acute type I aortic dissection.

METHODS

From 2009 to 2016, 85 patients underwent total arch replacement for acute type I aortic dissection with residual dissected thoracoabdominal aorta. Forty patients (47%) underwent serial computed tomography scans that were sufficient for analysis. Among these, 14 (35%) underwent total arch replacement via the frozen elephant trunk procedure. Intimal tears were analyzed (size and number) at 3 different levels (level 1, proximal descending thoracic aorta; level 2, distal descending thoracic aorta; level 3, abdominal aorta). Aortic diameter was measured at 4 levels (pulmonary artery bifurcation, celiac axis, maximal abdominal aorta, and maximal thoracoabdominal aorta) using serial follow-up computed tomography scans. The linear mixed model for a repeated-measures random intercept and slope model was used. The rate of freedom from reintervention was analyzed.

RESULTS

In the unadjusted analysis, initial diameter of pulmonary artery bifurcation level, number of intimal tears, presence of 3- or 5-mm intimal tears, and frozen elephant trunk were not significant factors for aortic dilation or shrinking. The significant factors for aortic dilation were intimal tear location and number of visceral branches from the false lumen. The 3-year freedom from reintervention rate was significantly higher in patients with intimal tears 3 mm or greater at level 3 than in those with tears at level 1 (94.1% vs 37.5%, log-rank, P < .001).

CONCLUSIONS

Intimal tear in the proximal descending thoracic aorta is the most important factor for aortic dilation and reintervention in acute type I aortic dissection after total arch replacement.

Relationship between serum cortisol level and degree of false lumen thrombosis in patients with uncomplicated type B aortic dissection

Partial thrombosis of the false lumen in uncomplicated type B aortic dissection (uTBAD) is associated with an increased late mortality risk. Whether the serum cortisol level can affect false lumen thrombosis in patients with uTBAD has not been well characterized. This study was performed on 87 patients with uTBAD. A curve-fitting method was used to analyze the relationship between serum cortisol and partial thrombosis of false lumen. Univariate and multivariate logistic regression analyses were used to identify false lumen partial thrombosis–associated serum cortisol. Curve-fitting’s result revealed a characteristic U shape, and 14.0 µg/dL was considered as the cutoff point for serum cortisol. The results of univariate and multivariate logistic regression analyses suggested that when trisecting the serum cortisol level into three parts, the low and high levels of serum cortisol could significantly affect the occurrence of false lumen partial thrombosis compared with the middle level. The odds ratio value of the low and high levels of serum cortisol was 6.12 and 4.65, respectively, in the univariate analysis, and 24.32 and 3.93, respectively, in the multivariate analysis. Low or high levels of serum cortisol might influence the natural result of uTBAD through affecting the false lumen thrombosis.

Type B Aortic Dissections: Current Guidelines for Treatment

Stanford type B aortic dissections (TBADs) involve the descending aorta and can present with complications, including malperfusion syndrome or aortic rupture, which are associated with significant morbidity and mortality if left untreated. Clinical diagnosis is straightforward, typically confirmed using CT angiography. Treatment begins with immediate anti-impulse medical therapy. Acute TBAD with complications should be repaired with emergent thoracic endovascular aortic repair (TEVAR). Uncomplicated TBAD with high-risk features should undergo TEVAR in the subacute phase. Open surgical repair is seldom required and reserved only for select cases. It is critical to follow these patients clinically and radiographically in the outpatient setting.