Update in acute aortic syndrome: intramural hematoma and incomplete dissection as new disease entities

Late Outcomes of Surgery Versus Medical Therapy in Patients With Type A Aortic Intramural Hematoma: Meta-Analysis of Reconstructed Time-to-Event Data

The effect of an initial surgical approach (in comparison with initial medical therapy) in acute type A intramural hematoma remains insufficiently explored. We designed a pooled analysis of Kaplan-Meier-derived individual patient data from studies with follow-up for overall survival (all-cause death). Restricted mean survival time was calculated to evaluate lifetime gain or loss. The Risk of Bias in Non-Randomized Studies of Interventions tool (ROBINS-I) was used to assess risk of bias. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) was applied to assess certainty of evidence. Eight studies met our eligibility criteria, including a total of 654 patients (311 patients treated with surgery and 343 patients treated with medical therapy alone). All the studies were non-randomized and observational. The median follow-up was 4.6 years (interquartile range 1.0 to 7.7). Patients who underwent surgery had a significantly lower risk of mortality compared with patients receiving medical therapy alone (hazard ratio 0.51, 95% confidence interval 0.35 to 0.74, p <0.001). The restricted mean survival time was overall 1.1 years greater with surgery compared with medical therapy, and this difference was statistically significant (p <0.001), which means that surgery is associated with lifetime gain. The overall risk of bias (ROBINS-I) was considered moderate-to-serious and the certainty of evidence (GRADE) was deemed to be low. In conclusion, in the overall follow-up, surgery as the initial approach was associated with better late survival and lifetime gain in comparison with medical therapy alone in the setting of acute type A aortic intramural hematoma; however, high-quality randomized trials are warranted to establish the efficacy of the surgical strategy.

Clinical characteristics and outcomes of Stanford type B aortic intramural hematoma: A single centre experience

Objective

To compare the clinical characteristics of Stanford type B aortic intramural hematoma (IMH) and Stanford type B aortic dissection (AD), and to identify the differences between thoracic endovascular aortic repair (TEVAR) and medical management (MM) in the Stanford type B IMH patients.

Methods

A retrospective observational study was conducted in patients treated between January 2015 and December 2016. The clinical characteristics and CT images of patients with type B IMH and type B AD were compared, and the clinical characteristics and CT images of patients in the type B IMH group who were treated with TEVAR and MM were compared.

Results

A total of 176 patients were included in this study, including 62 patients of type B IMH and 114 patients of type B AD. Five patients died in the IMH group and three in the AD group. The proximal hematoma or entry tear in both groups was mainly located in the descending aorta, and the proportion of the iliac artery involved in the AD group was significantly higher than that in the IMH group (31.6% vs. 8.1% P < 0.05). There were 50 MM patients and 12 TEVAR patients in the IMH group. No death occurred in the TEVAR group, while five patients in the MM group died. Seven patients in the MM group had disease progression vs. 12 in the TEVAR group (P < 0.05). The patients in the TEVAR group had more intima lesions than those in the MM group (83.3% vs. 30.0%, P < 0.05). TEVAR group involved more iliac artery hematoma than MM group (33.3% vs. 2.0%, P < 0.05). The maximum thickness of hematoma in TEVAR group was 14.9 ± 3.4 mm, which was significantly larger than that of MM group (10.2 ± 2.8 mm) (P < 0.05).

Conclusion

In the diagnosis of IMH, patients' symptoms and high-risk signs of CTA should be paid attention to. TEVAR therapy should be actively considered on the basis of effective medical management when there are intima lesions (ULP/PAU), increased aortic diameter and hematoma thickness, extensive hematoma involvement, and pleural effusion.

In situ visualization of aortic dissection propagation in notched rabbit aorta using synchrotron X-ray tomography

Aortic dissection is a complex, intramural, and dynamic condition involving multiple mechanisms, hence, difficult to observe. In the present study, a controlled in vitro aortic dissection was performed using tension-inflation tests on notched rabbit aortic segments. The mechanical test was combined with conventional (cCT) and synchrotron (sCT) computed tomography for in situ imaging of the macro- and micro-structural morphological changes of the aortic wall during dissection. We demonstrate that the morphology of the notch and the aorta can be quantified in situ at different steps of the aortic dissection, and that the notch geometry correlates with the critical pressure. The phenomena prior to propagation of the notch are also described, for instance the presence of a bulge at the tip of the notch is identified, deforming the remaining wall. Finally, our method allows us to visualize for the first time the propagation of an aortic dissection in real-time with a resolution that has never previously been reached. STATEMENT OF SIGNIFICANCE: With the present study, we investigated the factors leading to the propagation of aortic dissection by reproducing this mechanical process in notched rabbit aortas. Synchrotron CT provided the first visualisation in real-time of an aortic dissection propagation with a resolution that has never previously been reached. The morphology of the intimal tear and aorta was quantified at different steps of the aortic dissection, demonstrating that the early notch geometry correlates with the critical pressure. This quantification is crucial for the development of better criteria identifying patients at risk. Phenomena prior to tear propagation were also described, such as the presence of a bulge at the tip of the notch, deforming the remaining wall.

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.

Iatrogenic Aortic Root Injury from Coronary Interventions: Early and Follow-up CT Imaging Findings

Aortic injury represents a rare but potentially fatal complication of invasive coronary angiography. The authors present a series of four patients with aortic injury after invasive coronary angiography and intervention (mean age, 71 years; three women). In three patients, CT showed subintimal staining from undiluted contrast media (CM) in the aortic root with no communication to the aortic lumen. Short-term follow-up CT showed resolution of CM staining in all patients. Classic aortic dissection occurred in one patient, with undiluted CM from invasive angiography in the false lumen in the aortic root. Preliminary evidence suggests that iatrogenic injury from invasive coronary angiography resulting in subintimal CM staining of the aortic wall at CT, without evidence of communication with the lumen of the aortic root, shows favorable short-term outcome. Keywords: CT Angiography, Percutaneous, Fluoroscopy Supplemental material is available for this article. © RSNA, 2021.

Therapeutic management of acute type A aortic intramural hematoma

OBJECTIVES

The proper therapeutic management for acute type A aortic intramural hematoma (IMH) is still controversial. The purpose of this study was to compare the outcomes following emergency surgery or conservative treatment for patients with this disease.

METHODS

From January 2015 to December 2018, 124 consecutive patients were diagnosed with an acute type A aortic IMH and were included in this study. According to our surgical indications, they were divided into two groups: an operation group (OG) and a conservative treatment group (CG).

RESULTS

Of 124 patients, 83 (66.9%) patients accepted emergency surgery and 41 (33.1%) patients accepted strict conservative treatment. There were no differences between these two groups in early mortality and complications. However, the late mortality of patients in the CG was significantly higher than for patients in the OG. A maximum aortic diameter in the ascending aorta and aortic arch ≥ 45 mm and maximum thickness of IMH in the same section ≥ 8 mm were risk factors for IMH related death in patients undergoing conservative treatment.

CONCLUSIONS

The mortality associated with emergency surgery for patients with acute type A aortic IMH was satisfactory. In clinical centers with well-established surgical techniques and postoperative management, emergency surgical treatment may provide a better outcome than medical treatment for patients with acute type A aortic IMH.

A Parametric Study on Factors Influencing the Onset and Propagation of Aortic Dissection Using the Extended Finite Element Method

OBJECTIVE

Aortic dissection is a life-threatening event which starts most of the time with an intimal tear propagating along the aortic wall, while blood enters the medial layer and delaminates the medial lamellar units. Studies investigating the mechanisms underlying the initiation sequence of aortic dissection are rare in the literature, the majority of studies being focused on the propagation event. Numerical models can provide a deeper understanding of the phenomena involved during the initiation and the propagation of the initial tear, and how geometrical and mechanical parameters affect this event. In the present paper, we investigated the primary factors contributing to aortic dissection.

METHODS

A two-layer arterial model with an initial tear was developed, representing three different possible configurations depending on the initial direction of the tear. Anisotropic damage initiation criteria were developed based on uniaxial and shear experiments from the literature to predict the onset and the direction of crack propagation. We used the XFEM-based cohesive segment method to model the initiation and the early propagation of the tear along the aorta. A design of experiment was used to quantify the influence of 7 parameters reflecting crack geometry and mechanics of the wall on the critical pressure triggering the dissection and the directions of propagation of the tear.

RESULTS

The results showed that the obtained critical pressures (mean range from 206 to 251 mmHg) are in line with measurement from the literature. The medial tensile strength was found to be the most influential factor, suggesting that a medial degeneration is needed to reach a physiological critical pressure and to propagate a tear in an aortic dissection. The geometry of the tear and its location inside the aortic wall were also found to have an important role not only in the triggering of tear propagation, but also in the evolution of the tear into either aortic rupture or aortic dissection. A larger and deeper initial tear increases the risk of aortic dissection.

CONCLUSION

The numerical model was able to reproduce the behaviour of the aorta during the initiation and propagation of an aortic dissection. In addition to confirm multiple results from the literature, different types of tears were compared and the influence of several geometrical and mechanical parameters on the critical pressure and direction of propagation was evaluated with a parametric study for each tear configuration.

SIGNIFICANCE

Although these results should be experimentally validated, they allow a better understanding of the phenomena behind aortic dissection and can help in improving the diagnosis and treatment of this disease.

Epidemiology and management of aortic disease: aortic aneurysms and acute aortic syndromes

The aorta is the 'greatest artery', through which oxygenated blood is delivered from the left ventricle to end organs with each cardiac cycle (200 million litres of blood transported in an average lifetime). The aorta can be affected by a wide spectrum of acute factors (such as cocaine use, weight lifting and trauma) and chronic acquired and/or genetic conditions (such as systemic arterial hypertension and phaeochromocytoma), which variously lead to increased aortic wall stress. The medial layer of the aorta can also be subject to abnormalities (such as Marfan syndrome, bicuspid aortic valve, inflammatory vasculitis, atherosclerosis and infections). Despite important advances in diagnostic and therapeutic interventions, data derived from registries and population-based studies highlight that the burden of aortic diseases remains high. Therefore, specific resources need to be allocated to design and implement preventive strategies (healthy lifestyles, modifications to cardiovascular risk factors, and educational and screening programmes) at individual and community levels. In this Review, we discuss the epidemiology, management and outcomes of the most common aortic diseases, namely, aortic aneurysms and acute aortic syndromes.

Aortic dissection extending from the brachiocephalic artery during transradial coronary catheterization: a case report

BACKGROUND

Iatrogenic acute aortic dissection (AD) is an extremely rare but devastating complication during cardiac catheterization. It can be treated conservatively if it develops in a retrograde form or manifests as an intramural hematoma (IMH) with a micro-intimal tear in the absence of instability. However, only a few reports exist on its natural course and long-term outcomes.

CASE PRESENTATION

A 78-year-old woman presented to the emergency department with acute chest discomfort. Elective cardiac catheterization was performed via the right radial artery. The patient's brachiocephalic artery was so tortuous that the hydrophilic soft guidewire had to be exchanged for a stiffer one. However, the stiff wire caused the dissection of a tortuous brachiocephalic artery that extended from the sinuses of Valsalva to the proximal descending aorta. Emergent computed tomography showed crescentic aortic wall thickening without a dissection flap. The patient had cardiac tamponade and a gradually thickening thrombosed false lumen. Although the patient was unstable during the first 2 weeks, she was stabilized during hospital stay with only conservative treatment. Consequently, she has been well for over 5 years.

CONCLUSIONS

Even though the patient showed ominous findings, a good prognosis was expected because the AD was mainly retrograde. Furthermore, the thrombosed false lumen mimicked an IMH on imaging. To the best of our knowledge, this is the first report of an extensive iatrogenic AD originating from the brachiocephalic artery during right transradial catheterization that was treated conservatively despite clinical instability.

Prediction of adverse events in patients with initially medically treated type A intramural hematoma

BACKGROUND

Prior studies provided limited data regarding natural history of initially medically treated type A intramural hematoma (IMH).

OBJECTIVES

To develop predictive models for adverse aorta-related events in patients with type A IMH.

METHODS

We performed a retrospective pooled analysis of individual patient data, including baseline clinical and CT characteristics. All patients enrolled were followed up for adverse aorta-related events, defined as a composite of aortic disease-related death and the presence of aortic complications that required aortic invasive treatment.

RESULTS

A total of 172 patients (52.9% men) were included, with a mean age of 61.1 ± 11.2 years. During a median follow-up time of 770.5 (45.3-1695.8) days, 60 patients (34.9%) experienced adverse aorta-related events. In Cox regression model for predicting adverse aorta-related events, hypertension (HR = 3.78, p = .067), MAD (HR = 1.05, p = .018), presence of ULP (HR = 2.43, p = .002) and pericardial effusion (HR = 1.65, p = .061) were independently associated with adverse aorta-related events. A majority of the adverse aorta-related events (n = 46, 76.7%) occurred within acute and subacute phase (90 days) of IMH. In predictive model for 90 days aortic events, MAD≥50.7 mm (OR = 2.79, p = .006) and presence of ULP (OR = 3.20, p = .002) were independent predictors. C statistic of the predictive model were 0.71 (p < .001).

CONCLUSIONS

Predictive models including baseline clinical and CT characteristics as predictors allow for accurate estimation of risk of adverse aorta-related events in patients with type A IMH. The proposed predictive models are helpful for risk estimates and decision making.

Clinical features and surgical outcomes of type A intramural hematoma

Background

Data on the clinical features and surgical outcomes of type A intramural hematoma (IMH) in Chinese patients are very limited. We aimed to present the surgical experiences on type A IMH in our center, and report early and late outcomes.

Methods

From February 2012 to April 2018, 106 consecutive patients underwent open surgery for type A IMH at our hospital. We adopted emergent operation for patients with cardiac tamponade or other severe complications, and recommended initial medical treatment followed by elective surgery for stable patients. The composite endpoints included operative mortality, permanent nerve damage (stroke, paraplegia), and new-onset renal failure necessitating hemodialysis. Risk factors for operative mortality and the composite endpoints were identified using univariable and multivariable logistic regression model analysis. The survival and freedom from aortic events were analyzed using a Kaplan-Meier surviving curve and a log-rank test.

Results

Except 1 patient receiving emergent surgery (within 24 hours from onset) because of cardiac tamponade and cerebral malperfusion, all patients received initial medical treatment and delayed surgery. Two patient developed pericardial tamponade while waiting for surgery, and then received emergent surgery. Preoperative conversion to aortic dissection (AD) was noted in no patient. The operative techniques included ascending aorta replacement in 9 patients, hemiarch replacement in 18 patients, total arch replacement (TAR) with frozen elephant trunk (FET) in 45 patient and hybrid aortic arch repair in 34 patients. The mean cardiopulmonary bypass (CPB) time and cross-clamp time were 138.7±41.6 and 79.3±27.8 min, respectively. The operative mortality was 1.9% (2/106). And the composite endpoints occurred in 7 patients. Multivariable logistic regression analysis showed CPB time ≥200 min and chronic kidney disease were risk factors for the composite endpoints. The follow-up data were available in 97 survivors, with the mean follow-up time of 30.8±16.2 months. Three patients died and 5 patients developed aortic events during the follow-up. The overall survival at 1-, 3- and 5-year were 97.0%, 95.3%, and 79.4%, respectively. And freedom from aortic events at 1-, 3- and 5-year were 97.7%, 95.3% and 89.4%, respectively.

Conclusions

Our strategy had got low mortality and excellent mid-term survival in patients with type A IMH. Therefore, our strategy was suitable for the surgical repair of type A IMH in Chinese population.

Beyond the term penetrating aortic ulcer: A morphologic descriptor covering a constellation of entities with different prognoses

Penetrating aortic ulcer (AU) is defined as localized disruption of the intimal layer of the aortic wall, resulting in a crater-like lesion outpouching from the vessel contour. AU is a generic term which encompasses a constellation of entities with different etiologies and prognoses and may be a complication of infective, inflammatory, traumatic, iatrogenic, atherosclerotic processes or intramural hematoma. One of the most challenging scenarios of AU for a differential diagnosis, but also for treatment implications, is when they are associated with acute aortic syndrome. Despite advances in the field of aortic disease, lack of consensus defining these lesions and the significant semantic confusion in the medical literature of the acronym PAU (for penetrating aortic ulcer but also for penetrating atherosclerotic ulcer) have given rise to controversy in guidelines and expert consensus, leading to the same treatment being recommended for entities with different etiology and prognosis. Moreover, in the medical literature, most diagnoses were mainly based on imaging techniques which identified AU regardless of clinical symptoms, surrounding imaging findings or dynamic morphologic changes. In this Review, we provide the latest insight into the differential diagnosis between AU, also called penetrating aortic ulcers, based on clinical context and the newest imaging characteristics to aid treatment decision-making.

Acute aortic syndromes: diagnosis and management, an update

Acute aortic syndromes (AAS) encompass a constellation of life-threatening medical conditions including classic acute aortic dissection (AAD), intramural haematoma, and penetrating atherosclerotic aortic ulcer. Given the non-specific symptoms and physical signs, a high clinical index of suspicion is necessary to detect the disease before irreversible lethal complications occur. In order to reduce the diagnostic time delay, a comprehensive flowchart for decision-making based on pre-test sensitivity of AAS has been designed by the European Society of Cardiology guidelines on aortic diseases and should be thus applied in the emergency scenario. When the definitive diagnosis is made, prompt and appropriate therapeutic interventions should be undertaken if indicated by a highly specialized aortic team. Urgent surgery for AAD involving the ascending aorta (Type A) and medical therapy alone for AAD not involving the ascending aorta (Type B) are typically recommended. In complicated Type B AAD, thoracic endovascular aortic repair (TEVAR) is generally indicated. On the other hand, in uncomplicated Type B AAD, pre-emptive TEVAR rather than medical therapy alone to prevent late complications, while intuitive, requires further study in randomized cohorts. Finally, it should be highlighted that there is an urgent need to increase awareness of AAS worldwide, including dedicated education/prevention programmes, and to improve diagnostic and therapeutic strategies, outcomes, and lifelong surveillance.

Doppler ultrasound diagnosis of transient leg malperfusion caused by dynamic obstruction in a patient with chronic aortic dissection

Leg malperfusion caused by dynamic obstruction is a serious complication of aortic dissection. A diagnosis of the malperfusion is difficult because it is made mainly on the basis of nonspecific symptoms such as intermittent claudication and numbness on walking. In the present study, we reported on a case of a 51-year-old man with leg malperfusion in chronic aortic dissection diagnosed by Doppler ultrasound. The combination of bisferious and dampened velocity waveform changes after walking may lead us to suspect a leg malperfusion caused by dynamic obstruction.

Conditional deletion of Rcan1 predisposes to hypertension-mediated intramural hematoma and subsequent aneurysm and aortic rupture

Aortic intramural hematoma (IMH) can evolve toward reabsorption, dissection or aneurysm. Hypertension is the most common predisposing factor in IMH and aneurysm patients, and the hypertensive mediator angiotensin-II induces both in mice. We have previously shown that constitutive deletion of Rcan1 isoforms prevents Angiotensin II-induced aneurysm in mice. Here we generate mice conditionally lacking each isoform or all isoforms in vascular smooth muscle cells, endothelial cells, or ubiquitously, to determine the contribution to aneurysm development of Rcan1 isoforms in vascular cells. Surprisingly, conditional Rcan1 deletion in either vascular cell-type induces a hypercontractile phenotype and aortic medial layer disorganization, predisposing to hypertension-mediated aortic rupture, IMH, and aneurysm. These processes are blocked by ROCK inhibition. We find that Rcan1 associates with GSK-3β, whose inhibition decreases myosin activation. Our results identify potential therapeutic targets for intervention in IMH and aneurysm and call for caution when interpreting phenotypes of constitutively and inducibly deficient mice.

Recommendations for accurate CT diagnosis of suspected acute aortic syndrome (AAS)--on behalf of the British Society of Cardiovascular Imaging (BSCI)/British Society of Cardiovascular CT (BSCCT)

Accurate and timely assessment of suspected acute aortic syndrome is crucial in this life-threatening condition. Imaging with CT plays a central role in the diagnosis to allow expedited management. Diagnosis can be made using locally available expertise with optimized scanning parameters, making full use of recent advances in CT technology. Each imaging centre must optimize their protocols to allow accurate diagnosis, to optimize radiation dose and in particular to reduce the risk of false-positive diagnosis that may simulate disease. This document outlines the principles for the acquisition of motion-free imaging of the aorta in this context.

Complicated Acute Aortic Syndromes Affecting the Descending Thoracic Aorta: Endovascular Treatment Compared With Open Repair

BACKGROUND

For patients with complicated acute thoracic aortic syndromes, endovascular treatment, when feasible, is preferred over open surgery. However, there are limited data on the long-term benefits of endovascular treatment in complicated acute aortic syndromes affecting the descending thoracic aorta.

HYPOTHESIS

The endovascular treatment is expected to have more favorable long-term mortality and fewer late reintervention in complicated acute thoracic aortic syndromes.

METHODS

Of 155 consecutive patients with acute aortic syndromes, 94 met the inclusion criteria of the study; 63 underwent endovascular repair (group 1) and 31 underwent open repair (group 2). Patients with a diagnosis of acute aortic syndrome localized in the descending thoracic aorta distal to the emergence of the left subclavian artery, complicated by rupture, malperfusion syndrome, and/or acute aortic expansion, were included. Indications for repair of the descending thoracic aorta included impending rupture in 70.2%, malperfusion syndrome in 29.8%, and persistence of pain with aortic expansion (aortic diameter >40 mm) in 2 patients.

RESULTS

During the follow-up period (63.0 ± 24.6 months), the cumulative survival free from cardiovascular death rates at 5 years was 92.0% and 51.4% in group 1 and 2, respectively (log rank P = 0.0001). Late mortality related to the aorta was 1.6% with thoracic endovascular aortic repair and 0% with surgical treatment.

CONCLUSIONS

Endovascular treatment in patients with complicated acute thoracic aortic syndromes localized at the descending thoracic aorta is feasible and safe, with a lower rate of early complications and similar long-term benefits when compared with surgical treatment.

Paraparesis after Primary Percutaneous Coronary Intervention for ST-segment Elevation Myocardial Infarction: Combined Uncommon Complications of Acute Aortic Syndrome in a Patient

Acute aortic syndrome complicated by both ST-segment elevation myocardial infarction (STEMI) and spinal ischemia is exceedingly rare. We herein report the case of a 66-year-old man who presented with paraparesis after primary percutaneous coronary intervention for STEMI. He was found to have an intramural hematoma of the ascending aorta and a severe dissection in the descending aorta, which led to both STEMI and paraparesis.