Aortic Dissection and Other Acute Aortic Syndromes: Diagnostic Imaging Findings from Acute to Chronic Longitudinal Progression

Aortic dissection: How to identify it during an abdominal ultrasound examination and achieve a potentially lifesaving diagnosis

Aortic dissection (AD) is a rare and potentially fatal condition that may be diagnosed late. During an emergency or elective abdominal ultrasound (US) examination, when going to evaluate the abdominal aorta for other reasons, it may happen that we find ourselves suspecting an AD. It is therefore important to know the US characteristics of this pathology to avoid wrong or missed diagnoses. Here, we present our practical experience regarding the application of US in the study of the abdominal aorta, which allowed us on several occasions to find an unexpected dissection in patients brought to our attention for other reasons.

Pulmonary Artery Periadventitial Hematoma in a Patient with Aortic Intramural Hematoma: A Case Report

A pulmonary artery periadventitial hematoma is a rare complication of a Stanford type A intramural hematoma. As the proximal ascending aorta and pulmonary artery share a common adventitial layer, extravasated blood from the intramural hematoma in the ascending thoracic aorta may extend to beneath the adventitia of the pulmonary artery. The authors describe a case involving a 66-year-old male with acute chest pain who presented with a pulmonary artery periadventitial hematoma associated with a Stanford type A intramural hematoma.

Acute Aortic Syndromes from Diagnosis to Treatment-A Comprehensive Review

This work aims to provide a comprehensive description of the characteristics of a group of acute aortic diseases that are all potentially life-threatening and are collectively referred to as acute aortic syndromes (AASs). There have been recent developments in the care and diagnostic plan for AAS. A substantial clinical index of suspicion is required to identify AASs before irreversible fatal consequences arise because of their indefinite symptoms and physical indicators. A methodical approach to the diagnosis of AAS is addressed. Timely and suitable therapy should be started immediately after diagnosis. Improving clinical outcomes requires centralising patients with AAS in high-volume centres with high-volume surgeons. Consequently, the management of these patients benefits from the increased use of aortic centres, multidisciplinary teams and an "aorta code". Each acute aortic entity requires a different patient treatment strategy; these are outlined below. Finally, numerous preventive strategies for AAS are discussed. The keys to good results are early diagnosis, understanding the natural history of these disorders and, where necessary, prompt surgical intervention. It is important to keep in mind that chest pain does not necessarily correspond with coronary heart disease and to be alert to the possible existence of aortic diseases because once antiplatelet drugs are administered, a blocked coagulation system can complicate aortic surgery and affect prognosis. The management of AAS in "aortic centres" improves long-term outcomes and decreases mortality rates.

[Acute aortic syndrome]

Acute aortic syndrome embraces a group of heterogenous pathological entities involving the aortic wall with a common clinical profile. The current epidemiology, clinical presentation, diagnosis and treatment strategy are discussed in this review. Besides, the importance of multidisciplinary aortic teams, aortic centers and the implementation of an aortic code are emphasized.

Mathematical modeling and numerical simulation of arterial dissection based on a novel surgeon's view

This paper presents a mathematical model for arterial dissection based on a novel hypothesis proposed by a surgeon, Axel Haverich, see Haverich (Circulation 135(3):205-207, 2017. https://doi.org/10.1161/circulationaha.116.025407 ). In an attempt and based on clinical observations, he explained how three different arterial diseases, namely atherosclerosis, aneurysm and dissection have the same root in malfunctioning Vasa Vasorums (VVs) which are micro capillaries responsible for artery wall nourishment. The authors already proposed a mathematical framework for the modeling of atherosclerosis which is the thickening of the artery walls due to an inflammatory response to VVs dysfunction. A multiphysics model based on a phase-field approach coupled with mechanical deformation was proposed for this purpose. The kinematics of mechanical deformation was described using finite strain theory. The entire model is three-dimensional and fully based on a macroscopic continuum description. The objective here is to extend that model by incorporating a damage mechanism in order to capture the tearing (rupture) in the artery wall as a result of micro-injuries in VV. Unlike the existing damage-based model of the dissection in the literature, here the damage is driven by the internal bleeding (hematoma) rather than purely mechanical external loading. The numerical implementation is carried out using finite element method (FEM).

Contemporary Midterm Outcomes After Primary Repair of Chronic Type A Aortic Dissection

BACKGROUND

Without surgical repair, acute type A aortic dissection (TAAD) is usually fatal. However, some patients survive without an early operation and progress to the chronic phase. Contemporary outcomes of primary surgical repair of chronic TAAD are unclear, so we evaluated them at our single-practice service.

METHODS

During 1990 to 2021, 205 patients underwent repair of TAAD in the chronic phase (>60 days after onset). The 2 relevant DeBakey classifications were nearly equally represented: type I, 52% (n = 107), and type II, 48% (n = 98). The median interval between dissection onset and repair was 7 months (interquartile range, 3-25 months). Kaplan-Meier and competing-risk analyses provided time-dependent outcomes.

RESULTS

At the time of intervention, most patients (40%) had chronic symptoms. Type I patients were younger than type II patients; however, comorbidities were similar. Most patients (n = 183 [87%]) underwent hemiarch or total arch repair, although total arch replacement was more common in type I dissection (P < .001). There were 15 operative deaths (7%), and 7 strokes (3%) persisted to the time of death or discharge. No patient had persistent paraplegia. Median follow-up was 5 years (interquartile range, 2-11 years). The 5-year reoperation-free survival was 61% (95% CI, 54%-68%), and the incidence of reoperation was 3% (95% CI, 0.4%-5%). Patients with type I and type II dissection did not differ significantly in survival (P = .2).

CONCLUSIONS

Durable repair can be achieved with reasonable operative risk. Treatment is individualized and is associated with low rates of persistent neurologic complications. Despite differing operative approaches by DeBakey type, early and late outcomes were similar.

Clinical and imaging differences between Stanford Type B intramural hematoma-like lesions and classic aortic dissection

BACKGROUND

Intramural hematoma (IMH) and Aortic dissection (AD) have overlapping features. The aim of this study was to explore the differences between them by comparing the clinical manifestations and imaging features of patients with acute Stanford type B IMH-like lesions and acute Stanford type B AD (ATBAD).

METHODS

This study retrospectively analysed the clinical and computed tomography angiography (CTA) imaging data of 42 IMH-like lesions patients with ulcer-like projection (ULP) and 38 ATBAD patients, and compared their clinical and imaging features.

RESULTS

(1) The IMH-like lesions patients were older than the ATBAD patients (64.2 ± 11.5 vs. 50.9 ± 12.2 years, P < 0.001). The D-dimer level in the IMH-like lesions group was significantly higher than that in the ATBAD group (11.2 ± 3.6 vs. 9.2 ± 4.5 mg/L, P < 0.05). The incidence rate of back pain was significantly higher in the ATBAD group than in the IMH-like lesions group (71.1% vs. 26.2%, P < 0.05). (2) The ULPs of IMH-like lesions and the intimal tears of ATBAD were concentrated in zone 4 of the descending thoracic aorta. The ULPs of IMH-like lesions and the intimal tears of ATBAD were mainly in the upper quadrant outside the lumen (64.3% vs. 65.8%, P > 0.05). (3) The maximum diameter of the ULPs in IMH-like lesions was smaller than that of the intimal tears in ATBAD (7.4 ± 3.4 vs. 10.8 ± 6.8 mm, P = 0.005). The lumen compression ratio in the ULPs plane and the maximum compression ratio of the aortic lumen in the IMH-like lesions group were smaller than that in the ADBAD group (P < 0.05). Fewer aortic segments were involved in IMH-like lesions patients than in ATBAD patients (5.6 ± 2.2 vs. 7.1 ± 1.9 segments, P < 0.005). The IMH-like lesions group had less branch involvement than that of the ATBAD group (P < 0.001).

CONCLUSION

The degree of intimal tears, lumen compression ratio, extent of lesion involvement, and impact on branch arteries in ATBAD are more severe than that of IMH-like lesions. But for the ULPs of IMH-like lesions and intimal tears of ATBAD, they have astonishing similarities in the location of the partition and the lumen quadrant, we have reason to believe that intimal tear is the initial factor in the pathogenesis of this kind of disease, and their clinical and imaging manifestations overlap, but the severity is different. Concerning similarities between these two conditions, these two may be a spectrum of one disease.

The Role of Multimodality Imaging Approach in Acute Aortic Syndromes: Diagnosis, Complications, and Clinical Management

Acute aortic syndromes are life-threatening conditions with high morbidity and mortality. The principal pathological feature is acute wall damage with possible evolution towards aortic rupture. Accurate and timely diagnosis is mandatory to avoid catastrophic consequences. Indeed, misdiagnosis with other conditions mimicking acute aortic syndromes is associated with premature death. In this view, cardiovascular imaging is necessary for the correct diagnosis and management. Echocardiography, computed tomography, magnetic resonance imaging, and aortography allow for diagnosis, guarantee immediate treatment, and detect associated complications. Multimodality imaging is essential in the diagnostic work-up to confirm or rule out acute aortic syndromes. The aim of this review is to highlight the contemporary evidence on the role of single cardiovascular imaging techniques and multimodality imaging in the diagnosis and management of acute aortic syndromes.

Registry of Aortic Diseases to Model Adverse Events and Progression (ROADMAP) in Uncomplicated Type B Aortic Dissection: Study Design and Rationale

Purpose

To describe the design and methodological approach of a multicenter, retrospective study to externally validate a clinical and imaging-based model for predicting the risk of late adverse events in patients with initially uncomplicated type B aortic dissection (uTBAD).

Materials and Methods

The Registry of Aortic Diseases to Model Adverse Events and Progression (ROADMAP) is a collaboration between 10 academic aortic centers in North America and Europe. Two centers have previously developed and internally validated a recently developed risk prediction model. Clinical and imaging data from eight ROADMAP centers will be used for external validation. Patients with uTBAD who survived the initial hospitalization between January 1, 2001, and December 31, 2013, with follow-up until 2020, will be retrospectively identified. Clinical and imaging data from the index hospitalization and all follow-up encounters will be collected at each center and transferred to the coordinating center for analysis. Baseline and follow-up CT scans will be evaluated by cardiovascular imaging experts using a standardized technique.

Results

The primary end point is the occurrence of late adverse events, defined as aneurysm formation (≥6 cm), rapid expansion of the aorta (≥1 cm/y), fatal or nonfatal aortic rupture, new refractory pain, uncontrollable hypertension, and organ or limb malperfusion. The previously derived multivariable model will be externally validated by using Cox proportional hazards regression modeling.

Conclusion

This study will show whether a recent clinical and imaging-based risk prediction model for patients with uTBAD can be generalized to a larger population, which is an important step toward individualized risk stratification and therapy.Keywords: CT Angiography, Vascular, Aorta, Dissection, Outcomes Analysis, Aortic Dissection, MRI, TEVAR© RSNA, 2022See also the commentary by Rajiah in this issue.

Bib Sign in Proximal Descending Thoracic Aorta Rupture on CT Angiography: Presentation of a Paradigmatic Case

Thoracic aortic rupture may present with subtle clinical and CT-angiography findings. Recognition of the imaging features of early rupture is key for timely diagnosis and treatment. This report presents a new sign of incipient proximal thoracic aortic rupture on CT-angiography.

Ascending aortic intramural hematoma: current concepts

PURPOSE OF REVIEW

Type A intramural hematoma (TAIMH) is an acute aortic disease characterized by the presence of hematoma in the aortic media and involving the ascending aorta. Open repair seems to be the first treatment approach, although recent evidence highlights that the best management of TAIMH is controversial. This review will focus on the current concept for TAIMH management and factors affecting the decision making.

RECENT FINDINGS

Recent studies have evaluated the role of open and endovascular repair, as well as conservative management in patients with TAIMH. More specific imaging findings seem to affect decision making for urgent repair.

SUMMARY

Despite TAIMH's acute nature, conservative management seems to represent a valid option for urgent approach, presenting similar mortality to open and endovascular repair. Comparative data are limited, however, in experienced centers, any approach may be applied with encouraging results. Endovascular management, which is mainly applied to manage retrograde TAIMH, is related to lower mortality and morbidity compared to open repair in this group of patients while aortic remodeling seems beneficial with this approach. Imaging findings, as ulcer-like lesions, hematoma thickness, concomitant dissection and aortic diameter, related to higher complication rate, set the indication for interventional management. Further research, including prospective data and registries, and ideally, randomized data may further clarify the best approach and factors indicating urgent repair.

Natural history and clinical significance of aortic focal intimal flaps

Objective

Focal intimal flaps (FIF) are a variety of defects of the aorta that result in a short, flap-like projection into the lumen, and are often encountered in asymptomatic patients undergoing computed tomography angiography (CTA) surveillance for aortic aneurysm, but the natural history and clinical significance of such lesions has not yet been studied.

Methods

We retrospectively identified patients with an asymptomatic FIF and available imaging follow-up (>1 year). FIF was defined as flap-like intimal irregularity < 4 cm in length involving the thoracic aorta (TA), abdominal aorta (AA) or common iliac arteries (CIA). FIF characteristics included length and circumferential extent as well as the presence and size (width and depth) of associated penetrating aortic ulcers (PAUs). Patient characteristics, adverse events and history of surgical repair was determined by chart review. FIFs and associated PAUs were assessed for progression by comparing baseline and follow-up CTA studies.

Results

A total of 84 FIFs were identified in 77 patients. Average age was 69.2 ± 10.1 years, and 81% were male (81%). Common co-morbidities included: hypertension (78%), hyperlipidemia (68%), smoking (60%), coronary artery disease (41%), aortic aneurysm (34%), type II diabetes mellitus (27%) and prior cardiovascular surgery (25%). FIFs were most commonly located in the abdominal aorta (n = 50, 60%). Nearly all FIFs were associated with local atherosclerotic plaque (93%). Mean follow-up interval was 3.5 ± 2.6 years (259 cumulative follow-up years). Change in FIF length and local aortic diameter over follow-up were 0.7 ± 2.3 mm and 0.8 ± 1.1 mm, respectively. Nearly half (47%) of FIFs were associated with penetrating aortic ulcers (PAU) with baseline depth of 7.3 mm (IQR: 6.1–10.2) and change in depth of 0.5 ± 1.4 mm. Only 12% of FIFs and 0% of associated PAUs demonstrated growth (≥3 mm) at follow-up. No acute pathology developed in the location of FIFs and no aortic interventions were performed specifically to treat FIFs.

Conclusion

Focal intimal flaps identified in asymptomatic patients with aortic disease were co-localized with atherosclerotic plaque and PAUs, and demonstrated indolent behavior, not leading to significant growth or acute aortic events, supporting a conservative management approach.

MDCT Imaging of Non-Traumatic Thoracic Aortic Emergencies and Its Impact on Diagnosis and Management—A Reappraisal

Non-traumatic thoracic aorta emergencies are associated with significant morbidity and mortality. Diseases of the intimomedial layers (aortic dissection and variants) have been grouped under the common term of acute aortic syndrome because they are life-threatening conditions clinically indistinguishable on presentation. Patients with aortic dissection may present with a wide variety of symptoms secondary to the pattern of dissection and end organ malperfusion. Other conditions may be seen in patients with acute symptoms, including ruptured and unstable thoracic aortic aneurysm, iatrogenic or infective pseudoaneurysms, aortic fistula, acute aortic thrombus/occlusive disease, and vasculitis. Imaging plays a pivotal role in the patient’s management and care. In the emergency room, chest X-ray is the initial imaging test offering a screening evaluation for alternative common differential diagnoses and a preliminary assessment of the mediastinal dimensions. State-of-the-art multidetector computed tomography angiography (CTA) provides a widely available, rapid, replicable, noninvasive diagnostic imaging with sensitivity approaching 100%. It is an impressive tool in decision-making process with a deep impact on treatment including endovascular or open surgical or conservative treatment. Radiologists must be familiar with the spectrum of these entities to help triage patients appropriately and efficiently. Understanding the imaging findings and proper measurement techniques allow the radiologist to suggest the most appropriate next management step.

CT of the Difficult Acute Aortic Syndrome

Acute aortic syndrome (AAS) is classically attributed to three underlying pathologic conditions-aortic dissection (AD), intramural hematoma (IMH), and penetrating atherosclerotic ulcer (PAU). In the majority of cases, the basics of image interpretation are not difficult and have been extensively reviewed in the literature. In this article, the authors extend existing imaging overviews of AAS by highlighting additional factors related to the diagnosis, classification, and characterization of difficult AAS cases. It has been well documented that AAS is caused not only by an AD but by a spectrum of lesions that often have overlap in imaging features and are not clearly distinguishable. Specifically, phase of contrast enhancement, flow artifacts, and flapless AD equivalents can complicate diagnosis and are discussed. While the A/B dichotomy of the Stanford system is still used, the authors subsequently emphasize the Society for Vascular Surgery's new guidelines for the description of acute aortic pathologic conditions given the expanded use of endovascular techniques used in aortic repair. In the final section, atypical aortic rupture and pitfalls are described. As examples of pericardial and shared sheath rupture become more prevalent in the literature, it is important to recognize contrast material third-spacing and mediastinal blood as potential mimics. By understanding these factors related to difficult cases of AAS, the diagnostic radiologist will be able to accurately refine CT interpretation and thus provide information that is best suited to directing management. Online supplemental material is available for this article. ^©RSNA, 2021.

Acute Aortic Syndrome Revisited: JACC State-of-the-Art Review

The purpose of this paper is to describe all available evidence on the distinctive features of a group of 4 life-threatening acute aortic pathologies gathered under the name of acute aortic syndrome (AAS). The epidemiology, diagnostic strategy, and management of these patients has been updated. The authors propose a new and simple diagnostic algorithm to support clinical decision making in cases of suspected AAS, thereby minimizing diagnostic delays, misdiagnoses, and unnecessary advanced imaging. AAS-related entities are reviewed, and a guideline to avoid imaging misinterpretation is provided. Centralization of patients with AAS in high-volume centers with high-volume surgeons is key to improving clinical outcomes. Thus, the role of multidisciplinary teams, an "aorta code" (streamlined emergent care pathway), and aortic centers in the management of these patients is boosted. A tailored patient treatment approach for each of these acute aortic entities is needed, and as such has been summarized. Finally, a set of prevention measures against AAS is discussed.