Non-A non-B aortic dissection: A literature review

Multimodal Imaging and Clinical Features of Aortic Dissection in a Cat

An 11-year-old male castrated cat was presented for dyspnoea. Cardiomegaly and pulmonary oedema were identified radiographically. Echocardiography identified lesions of suspected aortic dissection consisting of a false lumen filled with echogenic material at the level of the aortic valve with aortic insufficiency. The cat developed pericardial effusion and chylothorax three months after the initial diagnosis. A computed tomography exam revealed a wall defect allowing connection between the true and beak-, spiral-shaped false lumen compressing the true lumen, which led to a diagnosis of aortic dissection. In addition, aortic wall calcification from the aortic root to the ascending aorta was identified. Ten weeks after the scan, the cat collapsed and died shortly after hospitalisation. The post-mortem examination revealed full-thickness aortic dissection of 2 mm and a beak-shaped lumen surrounding the true lumen, consistent with computed tomography findings. A histopathologic exam revealed aortic dissection at the tunica media, myocyte hypertrophy and endocardial fibrosis. This case report describes clinical, multimodal imaging and histopathological features of aortic dissection in a cat and is the first to describe the corresponding computed tomography and post-mortem findings. Aortic dissection should be considered as a differential diagnosis when true and false lumen is identified on echocardiographic and computed tomography tests.

Aortic Outcome after Implementation of a Treatment Strategy for Type B Aortic Dissection Involving the Aortic Arch

OBJECTIVE

To evaluate the outcomes achieved after implementing a treatment strategy for non-A non-B (NANB) (B 1-2 D according to the latest consensus document of the Society of Vascular Surgery (SVS) and Society of Thoracic Surgeons (STS) acute aortic dissection (AAD)).

METHODS

This retrospective observational study adhered to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist. All cases of NANB AAD (B 1-2 D) treated at our institution between January 2016 and December 2022 were reviewed. Morbidity, mortality, aortic-related reintervention, and remodeling were analyzed.

RESULTS

Among 519 cases of acute aortic syndrome, n = 22 (4.2%) patients presented with NANB AAD (B 1-2 D) (n = 16,72.7% men, mean age 61.5 years+/14.7). Eleven cases were managed with best medical treatment (BMT) alone. Among them, one patient (9.1%) died suddenly 2 days after diagnosis for aortic rupture. Frozen elephant trunk procedure (FET) was required in the remaining 11 patients: 7 (31.8%) needed emergent operation for risks of impending aortic rupture or retrograde aortic dissection extension, and 4 (26.7%) underwent delayed surgery within a month from initial presentation. Overall, in-hospital mortality was 9.1% with both FET and BMT. At a median follow-up of 40 months (range 2 days-200 months) no other deaths occurred. A statistically significant differences in the rate of false lumen thrombosis (100% vs 55.5%, P = 0.033), and a significant positive aortic remodeling in zone 3 (P < 0.001) and 4 (P = 0.038) were reported in operated versus medically managed patients.

CONCLUSIONS

The best treatment for NANB is not established. We advocate for medical stabilization with an operative approach that favors open surgery in the acute post dissection period, promotes aortic remodeling, and carries acceptable risk in centers where FET is performed routinely.

Midterm Outcome of Aortic Dissection Associated With Aberrant Subclavian Artery: A Single-Center Retrospective Observational Study

PURPOSE

The aberrant subclavian artery (aSA) is a rare anomaly of the aortic branches. Approximately 20-60% of patients with an aSA are associated with Kommerell's diverticulum (KD). These vascular anomalies have been reported to increase the risk of aortic rupture (4-19%) and aortic dissection. However, limited studies have investigated the treatment of aortic dissection in patients with aSA and KD. This study aims to investigate clinical characteristics and midterm follow-up outcomes of patients with aortic dissection associated with aSA.

MATERIALS AND METHODS

Between 2011 and 2021, a total of 48 patients with aSA anomalies underwent aortic dissection surgical intervention. Surgical interventions include open surgery, hybrid surgery, and endovascular therapy. Among them, 20 (41.7%) had Stanford type A dissection, 9 (18.8%) had Stanford type B dissection, and 19 (39.6%) had non-A non-B dissection. We report the early and midterm clinical outcomes including mortality, central nervous system complication and respiratory complication, and other operative outcomes including reintervention rates and endoleak. A subgroup analysis of the surgical and postoperative conditions was performed on Stanford type B and non-A non-B aortic dissection patients.

RESULTS

The mean age of the patient population was 48.81±9.65 years. The 30-day mortality rate was 12.5%. The overall mortality rate was 20.8%, with a median follow-up time of 4.5 years (interquartile range [IQR]: 2-8.75 years). Central nervous system complications occurred in 8 patients (16.7%), subclavian steal syndrome in 6 patients (12.5%), and respiratory complications in 3 patients (6.2%). The estimated Kaplan-Meier survival rates at 1 year, 3 years, 5 years, and 7 years after surgery were, respectively, 87.0%, 82.5%, 79.7%, and 75.1%. For Stanford type B and non-A non-B aortic dissection patients, the 30-day mortality rate between the open surgery group and the minimally invasive group had no statistically significant differences (18.3% vs 8.3%, p=0.815).

CONCLUSIONS

Surgical intervention for aSA patients with aortic dissection has poor outcomes. Early intervention might be considered for patients with aSA and KD to prevent the occurrence of aortic dissection.Clinical ImpactAberrant subclavian artery (aSA) and Kommerell's diverticulum (KD) have been reported to increase the risk of aortic rupture and aortic dissection. This study is currently the largest single-center retrospective study on aSA combined with aortic dissection, providing standardized data reporting and midterm follow-up of patients with this rare vascular anomaly.

Differences in In-Hospital and Follow-Up Outcomes Between Non-A Non-B Aortic Dissection and Type B Aortic Dissection Treated by Endovascular Based Treatment

OBJECTIVES

Non-A non-B aortic dissection (AD) is a rare and life-threatening medical emergency, and it has been controversial whether it should be managed as type B aortic dissection (TBAD). The study aims to compare in-hospital and follow-up outcomes between patients with non-A non-B AD and those with TBAD treated by endovascular based treatment (EBT).

METHODS

From January 2017 to December 2021, 96 consecutive patients with non-A non-B AD met the inclusion criteria and underwent EBT. Patients with TBAD were matched to patients with non-A non-B AD at a 1:1 ratio using propensity score matching analysis to correct for baseline confounding factors. The primary endpoint was all-cause mortality. Aortic-related events were defined as dissection-related death, aortic rupture, retrograde type A aortic dissection, reintervention, and type Ia endoleak.

RESULTS

Patients with non-A non-B AD required more TEVAR-related adjunctive procedures compared to TBAD patients during EBT and they required a longer ICU length of stay (36.0 vs 24.0 hours, P < .05) as well as a longer hospitalization (8.0 vs 7.0 days, P < .05) after EBT. There was no statistical difference in overall survival after EBT for patients with TBAD and non-A non-B AD. However, compared to patients with TBAD, non-A non-B AD patients had a higher rate of reintervention and experienced more aortic-related late events during follow-up.

CONCLUSION

Patients with non-A non-B acute AD who are treated with EBT do not have higher in-hospital or follow-up mortality rates compared to patients with type B AD. However, there is an increased risk of reintervention and aortic-related late events after the intervention during follow-up.

Non-A Non-B Acute Aortic Dissection: Is There Some Confusion in the Radiologist's Mind?

BACKGROUND

The aim of this study is to define and determine the rate of acute non-A-non-B aortic dissections, and to evaluate CT angiography findings and possible complications, as well as to discuss management strategies and currently available therapy. Non-A non-B type of aortic dissection is still a grey area in the radiologist's mind, such that it is not entirely clear what should be reported and completed in terms of this disease.

METHODS

A retrospective single-center study including 36 pre-treatment CT angiograms of consecutive patients (mean age: 61 years) between January 2012 and December 2022 with aortic dissection involving the aortic arch with/without the thoracic descending/abdominal aorta (type non-A non-B).

RESULTS

According to the dissection anatomy, we identified three modalities of spontaneous acute non-A-non-B anatomical configurations. Configuration 1 (n = 25) with descending-entry tear and retrograde arch extension (DTA entry). Configuration 2 (n = 4) with Arch entry tear and isolated arch involvement (Arch alone). Configuration 3 (n = 7) with Arch entry and anterograde descending (±abdominal) aorta involvement (Arch entry). CT angiogram findings, management, and treatment options are described.

CONCLUSIONS

Acute non-A non-B dissection represents an infrequent occurrence of aortic arch dissection (with or without involvement of the descending aorta) that does not extend to the ascending aorta. The complete understanding of its natural progression, distinct CT angiography subtypes, optimal management, and treatment strategies remains incomplete. Within our series, patients frequently exhibit a complex clinical course, often necessitating a more assertive approach to treatment compared to type B dissections.

Current knowledge and contemporary management of non-A non-B aortic dissections

Non-A non-B aortic dissection (AAD) is an infrequently documented condition, comprising of only a small proportion of all AADs. The unique anatomy of the aortic arch and the failure of the existing classifications to adequately define individuals with non-A non-B AAD, have led to an ongoing controversy around the topic. It seems that the clinical progression of acute non-A non-B AAD diverges from the typical type A and B dissections, frequently leading to serious complications and thus mandating early intervention. Currently, the available treatment methods in the surgical armamentarium are conventional open, endovascular techniques and combined hybrid methods. The optimum approach is tailored in every individual case and may be determined by the dissection’s location, extent, the aortic diameter, the associated complications and the patient’s status. The management of non-A non-B dissections still remains challenging and a unanimous consensus defining the gold standard treatment has yet to be reached. In an attempt to provide further insight into this perplexing entity, we performed a minireview of the literature, aiming to elucidate the epidemiology, clinical course and the optimal treatment modality.

Surgical treatment patterns and clinical outcomes of type B aortic dissection involving the aortic arch

OBJECTIVE

In the present report, we have described the outcomes of endovascular repair, hybrid arch repair, and open surgical repair for type B dissection involving the aortic arch (B_{1-2, D}).

METHODS

Cases of endovascular repair, hybrid arch repair, and open surgical repair performed between January 2015 and December 2019 for aortic dissection designated as B_{1-2, D} by the Society for Vascular Surgery/Society of Thoracic Surgeons classification were retrospectively analyzed. The primary end point was all-cause mortality at follow-up. The secondary end points included early mortality, early morbidities, and aortic-related late events. Kaplan-Meier curves were created to analyze survival from all-cause mortality and freedom from aortic-related late events in the endovascular, hybrid, and open groups. Propensity score matching and stratification (stratified by proximal dissection extension: B_{1, D} and B_{2, D}) were performed as sensitivity analyses to compare the outcomes among the three treatment patterns after controlling for major confounders.

RESULTS

The present study included 151 patients (men, 79.5%; mean age, 47.3 ± 10.5 years), with 72 (47.7%) in the endovascular group, 46 (30.5%) in the hybrid group, and 33 (21.8%) in the open group. No significant difference was noted in early mortality between the endovascular, hybrid, and open groups (1.4% vs 2.2% vs 3.0%; P = .791). The incidence of early endoleak was significantly greater (33.3% vs 13.0% vs 6.1%; P = .002) and the incidence of renal function deterioration was less (4.2% vs 26.1% vs 24.2%; P = .001) after endovascular repair vs hybrid arch repair and open surgery. After a median follow-up of 40.0 months (range, 0-84.0 months), no significant differences were found in all-cause mortality (5.6% vs 4.3% vs 3.0%; P = 1.0), aortic-related late events (16.7% vs 15.2% vs 12.1%; P = .834), or late endoleak (9.7% vs 4.3% vs 6.1%; P = .630) after endovascular, hybrid, and open surgery. The propensity score matching and stratification analyses displayed consistent outcomes for early mortality, all-cause mortality, and aortic-related late events among the three groups.

CONCLUSIONS

The mid- to long-term outcomes after endovascular repair, hybrid arch repair, and open surgical repair for type B dissection involving the aortic arch (B_{1-2, D}) were favorable and comparable in selected patients. Extensive experience and multidisciplinary teamwork are prerequisites for individualized strategies for repair of B_{1-2, D}.

Successive surgical repair of a progressive aortic dissection in a case of Loeys-Dietz Syndrome

INTRODUCTION

The Frozen Elephant Trunk technique is a well-established treatment for aortic dissections (Stanford Type A) involving the aortic arch and descending aorta. The Thoraflex™ Hybrid prosthesis (Vascutek Ltd.), consisting of a proximal flexible conduit and a distal self-expanding covered stent, has consistently shown positive results in the treatment of this condition.

CASE DESCRIPTION

The following is a description of such a staged reconstruction using the Thoraflex™ Hybrid Ante-Flo™ device, performed in a patient previously diagnosed with Loeys-Dietz Syndrome. After clamping the aorta proximally, an incision was taken at the distal end of the stent. Here, the distal end of the new prosthesis was inserted into the true lumen of the descending aorta and the stent was deployed. Following this, a bypass was established via the left atrium, and blood was returned to the lower body using the perfusion arm of the prosthesis with the proximal part of the descending aorta clamped. The collar of the prosthesis was sutured proximally to the aorta near the inlying previous stent. Air was removed via the perfusion arm of the prosthesis, which was then oversewn.

DISCUSSION

To date, hybrid prostheses have only been used on the proximal aorta in patients with aortic aneurysms and aortic dissections (Stanford Type A).

CONCLUSION

Using the described technique, it is possible to reconstruct the aortic anatomy using the available prostheses with accuracy and minimal complications.

“More or less”: management of type A aortic dissections in the endovascular era

The management of type A aortic dissection presents a major therapeutic challenge in modern surgical practice. Whilst the traditional dictum, to provide timely surgical intervention with the minimum treatment needed to repair the ascending aorta as well as the primary tear, may be a reasonable strategy in older patients, a tailored approach is desired for younger patients to manage the immediate life-threatening condition, as well as for the management of lifelong complications of the residual dissected aorta. Endovascular technology continues to advance, providing an adjunctive role to open cardiac repair presently to manage downstream aortic pathology, with the aim of striving towards a complete endovascular solution for type A aortic dissections.

Management of Ascending Aorta and Aortic Arch: Similarities and Differences Among Cardiovascular Guidelines

BACKGROUND

Ascending aorta and aortic arch diseases have an increasing interest among cardiovascular specialists regarding diagnosis and management. Innovations in endovascular surgery and evolution of open surgery have extended the indications for treatment in patients previously considered unfit for surgery. The aim of this systematic review of the literature was to present and analyze current cardiovascular guidelines for overlap and differences in their recommendations regarding ascending aorta and aortic arch diseases and the assessment of evidence.

METHODS

The English medical literature was searched using the MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials databases from January 2009 to December 2020. Recommendations on selected topics were analyzed, including issues from definitions and diagnosis (imaging and biomarkers) and indications for treatment to management, including surgical techniques, of the most important ascending aorta and aortic arch diseases.

RESULTS

The initial search identified 2414 articles. After exclusion of duplicate or inappropriate articles, the final analysis included 5 articles from multidisciplinary, cardiovascular societies published between 2010 and 2019. The definition of non-A-non-B aortic dissection is lacking from most of the guidelines. There is a disagreement regarding the class of recommendation and level of evidence for the diameter of ascending aorta as an indication. The indication for treatment of aortic disease may be individualized in specific cases while the growth rate may also affect the decision making. The role of endovascular techniques has not been established in current guidelines except by 1 society. Supportive evidence level in the management of aortic arch diseases remains limited.

CONCLUSION

In current recommendations of cardiovascular societies, the ascending aorta and aortic arch remain a domain of open surgery despite the introduction of endovascular techniques. Recommendations of the included societies are mostly based on expert opinion, and the role of endovascular techniques has been highlighted only from 1 society. The chronological heterogeneity apparent among guidelines and the inconsistency in evidence level should be also acknowledged. More data are needed to develop more solid recommendations for the ascending aorta and aortic arch diseases.

Is TEVAR really needed for uncomplicated type B aortic dissection?

Thoracic endovascular aortic repair (TEVAR) has quickly become the mainstay of treatment for acute aortic dissection, in particular cases of acute complicated Stanford Type B dissection (co-TBAD). Necessarily, TEVAR carries with it the risk of postoperative complications, including stroke and renal failure. As a result, the management of patients with uncomplicated type B aortic dissection (un-TBAD), which is generally accepted as being less severe, is safely managed via optimal medical therapy (OMT) alone. However, despite OMT, patients with un-TBAD are at substantial risk of severe disease progression requiring delayed intervention. The cost-benefit ratio associated with TEVAR for un-TBAD is therefore of key interest. Howard and colleagues produced a fascinating systematic review and meta-analysis investigating the clinical outcomes of TEVAR for complicated and uncomplicated TBAD. Their data suggest that there is no significant difference in in-hospital mortality or 5-year survival between TEVAR for un-TBAD and co-TBAD, although the 30-day mortality rate appeared to be higher in the co-TBAD cohort. Patients with co-TBAD appeared to also be at a higher risk of postoperative stroke and TEVAR endoleak, while un-TBAD patients were at a higher risk of postoperative renal failure. Further prospective research into these relationships is recommended to fully elucidate the comparative efficacies of TEVAR for un-TBAD and co-TBAD.