Intravascular Ultrasound Imaging as Applied to the Aorta: A New Tool for the Cardiovascular Surgeon

How to improve epidemiological trustworthiness concerning abdominal aortic aneurysms

BACKGROUND

Research on degenerative abdominal aortic aneurysms (AAA) is hampered by complex pathophysiology, sub-optimal pre-clinical models, and lack of effective medical therapies. In addition, trustworthiness of existing epidemiological data is impaired by elements of ambiguity, inaccuracy, and inconsistency. Our aim is to foster debate concerning the trustworthiness of AAA epidemiological data and to discuss potential solutions.

METHODS

We searched the literature from the last five decades for relevant epidemiological data concerning AAA development, rupture, and repair. We then discussed the main issues burdening existing AAA epidemiological figures and proposed suggestions potentially beneficial to AAA diagnosis, prognostication, and management.

RESULTS

Recent data suggest a heterogeneous scenario concerning AAA epidemiology with rates markedly varying by country and study cohorts. Overall, AAA prevalence seems to be decreasing worldwide while mortality is apparently increasing regardless of recent improvements in aortic-repair techniques. Prevalence and mortality are decreasing in high-income countries, whereas low-income countries show an increase in both. However, several pieces of information are missing or outdated, thus systematic renewal is necessary. Current AAA definition and surgical criteria do not consider inter-individual variability of baseline aortic size, further decreasing their reliability.

CONCLUSIONS

Switching from flat aortic-size thresholds to relative aortic indices would improve epidemiological trustworthiness regarding AAAs. Aortometry standardization focusing on simplicity, univocity, and accuracy is crucial. A patient-tailored approach integrating clinical data, multi-adjusted indices, and imaging parameters is desirable. Several novel imaging modalities boast promising profiles for investigating the aortic wall. New contrast agents, computational analyses, and artificial intelligence-powered software could provide further improvements.

Computed Tomography Angiography for Aortic Diseases

Aortic pathologies encompass a heterogeneous group of disorders, including acute aortic syndrome, traumatic aortic injury , aneurysm, aortitis, and atherosclerosis. The clinical manifestations of these disorders can be varied and non-specific, ranging from acute presentations in the emergency department to chronic incidental findings in an outpatient setting. Given the non-specific nature of their clinical presentations, the reliance on non-invasive imaging for screening, definitive diagnosis, therapeutic strategy planning, and post-intervention surveillance has become paramount. Commonly used imaging modalities include ultrasound, computed tomography (CT), and MR imaging. Among these modalities, computed tomography angiography (CTA) has emerged as a first-line imaging modality owing to its excellent anatomic detail, widespread availability, established imaging protocols, evidence-proven indications, and rapid acquisition time.

Optical coherence elastography and its applications for the biomechanical characterization of tissues

The biomechanical characterization of the tissues provides significant evidence for determining the pathological status and assessing the disease treatment. Incorporating elastography with optical coherence tomography (OCT), optical coherence elastography (OCE) can map the spatial elasticity distribution of biological tissue with high resolution. After the excitation with the external or inherent force, the tissue response of the deformation or vibration is detected by OCT imaging. The elastogram is assessed by stress-strain analysis, vibration amplitude measurements, and quantification of elastic wave velocities. OCE has been used for elasticity measurements in ophthalmology, endoscopy, and oncology, improving the precision of diagnosis and treatment of disease. In this article, we review the OCE methods for biomechanical characterization and summarize current OCE applications in biomedicine. The limitations and future development of OCE are also discussed during its translation to the clinic.

2022 ACC/AHA guideline for the diagnosis and management of aortic disease: A report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease" provides recommendations to guide clinicians in the diagnosis, genetic evaluation and family screening, medical therapy, endovascular and surgical treatment, and long-term surveillance of patients with aortic disease across its multiple clinical presentation subsets (ie, asymptomatic, stable symptomatic, and acute aortic syndromes).

METHODS

A comprehensive literature search was conducted from January 2021 to April 2021, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, CINHL Complete, and other selected databases relevant to this guideline. Additional relevant studies, published through June 2022 during the guideline writing process, were also considered by the writing committee, where appropriate.

STRUCTURE

Recommendations from previously published AHA/ACC guidelines on thoracic aortic disease, peripheral artery disease, and bicuspid aortic valve disease have been updated with new evidence to guide clinicians. In addition, new recommendations addressing comprehensive care for patients with aortic disease have been developed. There is added emphasis on the role of shared decision making, especially in the management of patients with aortic disease both before and during pregnancy. The is also an increased emphasis on the importance of institutional interventional volume and multidisciplinary aortic team expertise in the care of patients with aortic disease.

MR Angiography for Aortic Diseases

Aortic pathologic conditions represent diverse disorders, including aortic aneurysm, acute aortic syndrome, traumatic aortic injury, and atherosclerosis. Given the nonspecific clinical features, noninvasive imaging is critical in screening, diagnosis, management, and posttherapeutic surveillance. Of the commonly used imaging modalities, including ultrasound, computed tomography, and MR imaging, the final choice often depends on a combination of factors: acuity of clinical presentation, suspected underlying diagnosis, and institutional practice. Further research is needed to identify the potential clinical role and define appropriate use criteria for advanced MR applications such as four-dimenional flow to manage patients with aortic pathologic conditions.

2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease" provides recommendations to guide clinicians in the diagnosis, genetic evaluation and family screening, medical therapy, endovascular and surgical treatment, and long-term surveillance of patients with aortic disease across its multiple clinical presentation subsets (ie, asymptomatic, stable symptomatic, and acute aortic syndromes).

METHODS

A comprehensive literature search was conducted from January 2021 to April 2021, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, CINHL Complete, and other selected databases relevant to this guideline. Additional relevant studies, published through June 2022 during the guideline writing process, were also considered by the writing committee, where appropriate. Structure: Recommendations from previously published AHA/ACC guidelines on thoracic aortic disease, peripheral artery disease, and bicuspid aortic valve disease have been updated with new evidence to guide clinicians. In addition, new recommendations addressing comprehensive care for patients with aortic disease have been developed. There is added emphasis on the role of shared decision making, especially in the management of patients with aortic disease both before and during pregnancy. The is also an increased emphasis on the importance of institutional interventional volume and multidisciplinary aortic team expertise in the care of patients with aortic disease.

2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease" provides recommendations to guide clinicians in the diagnosis, genetic evaluation and family screening, medical therapy, endovascular and surgical treatment, and long-term surveillance of patients with aortic disease across its multiple clinical presentation subsets (ie, asymptomatic, stable symptomatic, and acute aortic syndromes).

METHODS

A comprehensive literature search was conducted from January 2021 to April 2021, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, CINHL Complete, and other selected databases relevant to this guideline. Additional relevant studies, published through June 2022 during the guideline writing process, were also considered by the writing committee, where appropriate.

STRUCTURE

Recommendations from previously published AHA/ACC guidelines on thoracic aortic disease, peripheral artery disease, and bicuspid aortic valve disease have been updated with new evidence to guide clinicians. In addition, new recommendations addressing comprehensive care for patients with aortic disease have been developed. There is added emphasis on the role of shared decision making, especially in the management of patients with aortic disease both before and during pregnancy. The is also an increased emphasis on the importance of institutional interventional volume and multidisciplinary aortic team expertise in the care of patients with aortic disease.

Vascular compression syndromes: a pictorial review

Vascular compression syndromes include a group of rare vascular changes due to extrinsic compression of veins or arteries by surrounding structures. These pathologies are often underestimated due to their rarity, clinicians’ poor level of knowledge, and the non-specificity of their symptoms. The best known are Eagle syndrome, thoracic outlet syndrome, nutcracker syndrome, May-Thurner syndrome, Dunbar syndrome, and popliteal entrapment syndrome. This work summarizes the main ultrasonographic characteristics, symptoms, and treatments of choice for these syndromes. Knowledge of these conditions’ characteristic signs is essential for the differential diagnosis. Failure to diagnose these rare diseases can expose patients to serious complications and risks to their health.

Intravascular Ultrasound in Branched and Fenestrated Endovascular Aneurysm Repair: Initial Experience in a Single-Center Cohort Study

PURPOSE

To evaluate intravascular ultrasound (IVUS) safety and efficacy to detect visceral stenting issues during complex endovascular aneurysm repair through branched and fenestrated repair (B-FEVAR).

MATERIALS AND METHODS

A single-center retrospective analysis of 33 bridging stents assessed intraoperatively using IVUS between January and September 2020 was performed. Ten aortic aneurysm patients [7 thoracoabdominal / 1 pararenal / 2 juxtarenal; 3 females; mean age 73 years [range 70-77 years]) were included. Eight BEVAR (5 standard; 2 custom-made) and 2 FEVAR (custom-made) were performed. The study assessed the safety and efficacy of IVUS utilization to detect immediate branch instability after visceral stenting in the case of B-FEVAR. The primary safety endpoint was defined as the absence of IVUS-related adverse events. The primary efficacy endpoint was defined as the composite of technical success of the IVUS-assessment in each target visceral vessels (TVVs), the rate of IVUS-findings divided as prompting additional maneuvers or not, and the incidence of postoperative computed tomography angiography findings compared with intraoperative assessment.

RESULTS

There were no IVUS-related adverse events. The technical success of the IVUS-assessment was achieved in all TVVs. No technical issues compromised the evaluation of the intended vessel. Among the 7 findings identified by IVUS, 3 were suspected at the angiography. In all, 57% (4/7) had normal final angiography. IVUS was able to detect a 12% (4/33) intraoperative branch instability not identified/suspected at the completion angiography. The IVUS assessment led to an immediate revision in 5 (15%) vessels. A total of 57% (4/7) of the issues were detected in patients undergoing primary BEVAR. The remaining 43% (3/7) was detected in patients undergoing secondary intervention for branch instability.

CONCLUSION

IVUS was safe as an adjunctive imaging technique to assess completion after B-FEVAR. It demonstrated efficacy in the detection of intraoperative issues missed by angiography. Further investigations are required to validate these promising results.

Aortic aneurysms and dissections: Unmet needs from physicians and engineers perspectives

The treatment of aortic disease is complex, requiring cardiothoracic and vascular surgeons to make pre-, post- and intraoperative decisions directly influencing patient survival and well-being. Despite tremendous advancement in vascular surgery and endovascular techniques in the last two decades, along with the abundance of research in the field, many unmet needs and unanswered questions remain. Tight collaboration between engineers and physicians is a keystone in translating new tools, techniques, and devices into practice. Here, we have gathered our perspective, as physicians and engineers, in several pressing issues associated with the diagnosis and treatment of aortic aneurysms and dissection, referring to the current knowledge and practice, signifying unmet needs as well as future directions.

Intravascular Ultrasound for Assessment of Residual Coarctation of the Aorta after Balloon Angioplasty in Infants

Intravascular ultrasound (IVUS) has been introduced as an accurate and minimally invasive diagnostic technique for the assessment of vascular anatomy and its abnormalities. We believe that IVUS can be used for clarifying the reasons for failure of balloon angiography in infantile coarctation of the aorta (CoA), because post-balloon angioplasty tearing, intimal flap, thrombosis and pseudoaneurysm of the aorta can be evaluated by IVUS with greater sensitivity and specificity. We aimed to assess the outcome of balloon angioplasty of CoA using angiography as the gold standard and IVUS as a new method in infants, comparing the two techniques for the evaluation of the diameter and area of CoA segment pre- and post-procedure. This cross-sectional study was performed on 18 infants hospitalized with a final diagnosis of CoA. All the infants underwent angiography and were also assessed by IVUS to measure the preoperative and postoperative diameter of the narrow segment in the two anterior-posterior and lateral views. In assessment by IVUS, the mean diameter of the coarctation site increased from 2.10 ± 0.30 mm to 4.50 ± 0.94 mm (P < 0.001). Similarly, the average minimum area of the coarctation level increased from 5.26 ± 1.50 mm² to 13.77 ± 3.48 mm² after angioplasty (P < 0.001). Comparing these findings, angiography and IVUS showed a high level of agreement. In the assessment of a dissection flap, there was a high level of agreement between angioplasty and IVUS before the procedure, but IVUS had higher accuracy after the procedure. Our study showed that IVUS was more reliable than angiography in the assessment of residual coarctation. IVUS yielded high sensitivity (58.3%) and specificity (100%) for discriminating the presence and absence of residual coarctation as well as the need for repeating the procedure. The assessment of coarctation before and after angioplasty procedures in children is possible using the IVUS method, with high accuracy. IVUS can offer greater accuracy than angiography in the evaluation of the coarctation area, detecting tears, dissection and flaps, and assessment of residual coarctation.

Intravascular Ultrasound for the Peripheral Vasculature-Current Applications and New Horizons

Intravascular ultrasound (IVUS) is a proven and rapidly developing imaging modality that can be used for a multitude of both diagnostic and interventional purposes. By allowing for superior intraluminal characterization, compared with angiography, IVUS has emerged as a technically valuable tool in interventional procedures such as transjugular intrahepatic portosystemic shunt/direct intrahepatic portosystemic shunt, venous interventions (May Thurner stenting, inferior vena cava filter placement, recanalization in the setting of chronic venous thrombosis/insufficiency), percutaneous fenestration in the setting of aortic dissection and angioplasty. Additional applications evaluating coronary arteries and plaque morphology have been described, but are outside the scope of this review. In addition to IVUS's merit as a pre- and intra-procedural guidance modality, there are also several advantages compared to the gold standard of angiography which include decreased need for iodinated contrast, decreased radiation exposure and decreased procedural times in certain cases. With current research, such as that aimed at supraharmonic imaging, further improvements in imaging depth, resolution and contrast to noise ratio are on the horizon.

In Vivo Assessment of Ascending and Arch Aortic Compliance

BACKGROUND

Dynamic compliance (Cd) of the adult thoracic ascending and arch aorta has had limited in vivo evaluation in patients with aortic disease. This study evaluates aortic compliance using intravascular ultrasound (IVUS) across a range of thoracic aortic diseases.

METHODS

Seventy-nine patients undergoing thoracic aortic endovascular procedures had Cd measurements of the ascending aorta proximal to the origin of the brachiocephalic trunk and distal to the origin of the left common carotid artery using IVUS before endograft deployment. Cd was calculated for each segment using the following equation, Cd = ΔD/(D • ΔP) where ΔD = change in aortic diameter, D = diameter in diastole, and ΔP = pulse pressure.

RESULTS

Mean Cd of the ascending aorta in all patients (18.4%/mm Hg) and aortic arch (16.5 %/100 mm Hg) did not differ significantly. Compliance was significantly lower in patients being treated for thoracic aortic aneurysm and penetrating ulcer than in patients with traumatic rupture, acute and chronic dissection (P = 0.009). Compliance was significantly higher in patients with aortic transection compared with thoracic aneurysm or penetrating ulcer (P = 0.001). Compliance decreased with age by 0.44 ± 0.06 (P = 0.001) per year in the ascending aorta and 0.41 ± 0.05 (P = 0.001) per year in the aortic arch. Compliance did not increase with diameter when adjusted for age (P = 0.65). Compliance measured in the ascending aorta in 7 patients after descending thoracic aortic endograft repair decreased to 12.6%/100 mm Hg, although not significant (P = 0.18).

CONCLUSIONS

Ascending and aortic arch compliance is significantly higher than reported for peripheral vessels. Thoracic aortic compliance decreases with age and is not related to aortic diameter. The results of the present study are important when considering the development of endoprosthesis devices and long-term effects on the thoracic aorta.

Towards a Reduced-Wire Interface for CMUT-Based Intravascular Ultrasound Imaging Systems

Having intravascular ultrasound (IVUS) imaging capability on guide wires used in cardiovascular interventions may eliminate the need for separate IVUS catheters and expand the use of IVUS in a larger portion of the vasculature. High frequency capacitive micro machined ultrasonic transducer (CMUT) arrays should be integrated with interface electronics and placed on the guide wire for this purpose. Besides small size, this system-on-a-chip (SoC) front-end should connect to the back-end imaging system with a minimum number of wires to preserve the critical mechanical properties of the guide wire. We present a 40 MHz CMUT array interface SoC, which will eventually use only two wires for power delivery and transmits image data using a combination of analog-to-time conversion (ATC) and an impulse radio ultra-wideband (IR-UWB) wireless link. The proof-of-concept prototype ASIC consumes only 52.8 mW and occupies 4.07 [Formula: see text] in a 0.35- [Formula: see text] standard CMOS process. A rectifier and regulator power the rest of the SoC at 3.3 V from a 10 MHz power carrier that is supplied through a 2.4 m micro-coax cable with an overall efficiency of 49.1%. Echo signals from an 8-element CMUT array are amplified by a transimpedance amplifier (TIA) array and down-converted to baseband by quadrature sampling using a 40 MHz clock, derived from the power carrier. The ATC generates pulse-width-modulated (PWM) samples at 2 × 10 MS/s with 6 bit resolution, while the entire system achieved 5.1 ENOB. Preliminary images from the prototype system are presented, and alternative data transmission and possible future directions towards practical implementation are discussed.

Transesophageal echocardiography guidance for stent-graft repair of a thoracic aneurysm is facilitated by the ability of partial stent deployment

Transesophageal echocardiography (TEE) is routinely used in our Institution for monitoring correct positioning of thoracic aortic stent grafts. We present a case of successful endovascular repair of three discrete thoracic aortic aneurysms with Zenith TX2 endovascular stent grafts in an 82-year-old female patient. Our focus is on the increased value of TEE guidance because of the ability of partial stent deployment and manipulation during insertion.

Retrograde ascending aortic dissection as an early complication of thoracic endovascular aortic repair

OBJECTIVE

Retrograde ascending aortic dissection (rAAD) is a potential complication of thoracic endovascular aortic repair (TEVAR), yet little data exist regarding its occurrence. This study examines the incidence, etiology, and outcome of this event.

METHODS

A prospective institutional database was used to identify cases of acute rAAD following TEVAR from a cohort of 309 consecutive procedures from March 2005 (date of initial Food and Drug Administration approval) to September 2010. The database was analyzed for the complication of rAAD as well as relevant patient and operative variables.

RESULTS

The incidence of rAAD was 1.9% (6/309); all cases occurred with proximal landing zone in the ascending aorta and/or arch (zones 0-2). All were identified in the perioperative period (range, 0-6 days) with 33% (2/6) 30-day/in-hospital mortality. Eighty-three percent (5/6) underwent emergent repair; one patient died without repair. rAAD patients were similar to the non-rAAD group (n = 303) across pertinent variables, including age, gender, race, and device size (all P > .1). rAAD incidence by aortic pathology was 1.0% (2/200) for aneurysm, 4.4% (4/91) for dissection, and 0% (0/18) for transection; P = .08. rAAD incidence by device was TAG (Gore) 1.0% (2/205), Talent (Medtronic) 4.7% (2/43), and Zenith TX2 (Cook) 3.6% (2/55). rAAD incidence was observed to be higher among patients with an ascending aortic diameter ≥ 4.0 cm (4.8% vs 0.9% for ascending diameter <4.0 cm); P = .047. Incidence was also higher with proximal landing zone in the native ascending aorta (zone 0) 6.9% (2/29) versus 1.4% for all others (4/280); P = .101. For patients with dissection pathology and an ascending aortic diameter ≥ 4.0 cm, 11% (3/28) suffered rAAD; with the combination of native ascending aorta (zone 0) landing zone measuring ≥ 4.0 cm, the incidence was 25% (2/8). Definitive diagnosis was by computed tomography angiography (n = 1), intraoperative transesophageal echocardiography (n = 3), intraoperative arteriography (n = 1), or postmortem autopsy (n = 1).

CONCLUSIONS

rAAD is a lethal early complication of TEVAR, which may be more common when treating dissection, with devices utilizing proximal bare springs or barbs for fixation, with native zone 0 proximal landing zone and with ascending aortic diameter ≥ 4 cm. Combinations of these risk factors may be particularly high risk. Intraoperative imaging assessment of the ascending aorta should be conducted following TEVAR to avoid under-recognition. National database reporting of this complication is needed to ensure safety and proper application of emerging TEVAR technology.

Imaging of Abdominal Aortic Aneurysm: the present and the future

Abdominal Aortic Aneurysm (AAA) is a common, progressive, and potentially lethal vascular disease. A major obstacle in AAA research, as well as patient care, is the lack of technology that enables non-invasive acquisition of molecular/cellular information in the developing AAA. In this review we will briefly summarize the current techniques (e.g. ultrasound, computed tomography, and magnetic resonance imaging) for anatomical imaging of AAA. We also discuss the various functional imaging techniques that have been explored for AAA imaging. In many cases, these anatomical and functional imaging techniques are not sufficient for providing surgeons/clinicians enough information about each individual AAA (e.g. rupture risk) to optimize patient management. Recently, molecular imaging techniques (e.g. optical and radionuclide-based) have been employed to visualize the molecular alterations associated with AAA, which are discussed in this review. Lastly, we try to provide a glance into the future and point out the challenges for AAA imaging. We believe that the future of AAA imaging lies in the combination of anatomical and molecular imaging techniques, which are largely complementary rather than competitive. Ultimately, with the right molecular imaging probe, clinicians will be able to monitor AAA growth and evaluate the risk of rupture accurately, so that the life-saving surgery can be provided to the right patients at the right time. Equally important, the right imaging probe will also allow scientists/clinicians to acquire critical data during AAA development and to more accurately evaluate the efficacy of potential treatments.

Application of high-frequency ultrasound for the detection of surgical anatomy in the rodent abdomen

Rats are used extensively in abdominal disease research. To monitor disease progress in vivo, high-frequency ultrasound (HFU) can be a powerful tool for obtaining high-resolution images of biological tissues. However, there is a paucity of data regarding the correlation between rat anatomy and corresponding HFU images. Twenty-four adult male Sprague-Dawley (SD) rats underwent abdominal scans using HFU (40 MHz) surgical procedures to identify abdominal organs and major vessels as well as in situ scanning to confirm the imaging results. The results were compared with those of human abdominal organs in ultrasonographic scans. The rat liver, paired kidneys, stomach, intestines, and major blood vessels were identified by HFU and the ultrasonic morphologies of the liver and kidneys showed clear differences between rats and humans. Clinically relevant anatomical structures were identified using HFU imaging of the rat abdomen, and these structures were compared with the corresponding structures in humans. Increased knowledge with regard to identifying the anatomy of rat abdominal organs by ultrasound will allow scientists to conduct more detailed intra-abdominal research in rodents.

Retrograde Ascending Aortic Dissection During or After Thoracic Aortic Stent Graft Placement

Background— Single-center reports have identified retrograde ascending aortic dissection (rAAD) as a potentially lethal complication of thoracic endovascular aortic repair (TEVAR).

Methods and Results— Between 1995 and 2008, 28 centers participating in the European Registry on Endovascular Aortic Repair Complications reported a total of 63 rAAD cases (incidence, 1.33%; 95% CI, 0.75 to 2.40). Eighty-one percent of patients underwent TEVAR for acute (n=26, 54%) or chronic type B dissection (n=13, 27%). Stent grafts with proximal bare springs were used in majority of patients (83%). Only 7 (15%) patients had intraoperative rAAD, with the remaining occurring during the index hospitalization (n=10, 21%) and during follow-up (n=31, 64%). Presenting symptoms included acute chest pain (n=16, 33%), syncope (n=12, 25%), and sudden death (n=9, 19%) whereas one fourth of patients were asymptomatic (n=12, 25%). Most patients underwent emergency (n=25) or elective (n=5) surgical repair. Outcome was fatal in 20 of 48 patients (42%). Causes of rAAD included the stent graft itself (60%), manipulation of guide wires/sheaths (15%), and progression of underlying aortic disease (15%).

Conclusions— The incidence of rAAD was low (1.33%) in the present analysis with high mortality (42%). Patients undergoing TEVAR for type B dissection appeared to be most prone for the occurrence of rAAD. This complication occurred not only during the index hospitalization but after discharge up to 1050 days after TEVAR. Importantly, the majority of rAAD cases were associated with the use of proximal bare spring stent grafts with direct evidence of stent graft–induced injury at surgery or necropsy in half of the patients.