Randomized comparison of strategies for type B aortic dissection: the INvestigation of STEnt Grafts in Aortic Dissection (INSTEAD) trial

What makes the difference between the natural course of a remaining type B dissection after type A repair and a primary type B aortic dissection?

OBJECTIVES

To analyse the outcome and need for intervention [surgery or thoracic endovascular aortic repair (TEVAR)] in patients after surgery for remaining type B dissection after type A repair and primary type B aortic dissection.

METHODS

Within a 10-year period, 247 patients with remaining type B after type A, and 112 patients with primary type B aortic dissection were analysed. We assessed the clinical outcome as well as the need for intervention (surgery or TEVAR) within the aortic arch and the thoracoabdominal aorta as well as risk factors.

RESULTS

The median follow-up was 23 months (interquartile range 5-52). There was a significant difference with regard to the status of the primary entry tear between patients after surgical repair of an acute type A aortic dissection and primary acute type B aortic dissection (patent vs. non-patent entry 35 vs. 83%, P < 0.001). The overall need for any kind of intervention (surgery or TEVAR) was 19%. Multivariate Cox regression analysis revealed a patent primary entry tear in patients after surgery for acute type A aortic dissection as an independent predictor for intervention (surgery or TEVAR) during follow-up [odds ratio (OR) 6.4; confidence interval (CI) 1.39-29.81, P = 0.017]. Multivariate Cox regression analysis did not reveal a patent primary entry tear in patients after acute type B aortic dissection as an independent predictor for intervention (surgery or TEVAR) during follow-up (OR 0.67; CI 0.27-1.69, P = 0.671). Finally, the thrombosis status of the false lumen was not an independent predictor for intervention (surgery or TEVAR) either in patients after surgery for acute type A aortic dissection (OR 3.46; CI 0.79-15.16, P = 0.100) or in patients after acute type B aortic dissection (OR 0.77; CI 0.31-1.93, P = 0.580).

CONCLUSIONS

A remaining type B dissection after type A repair and a primary type B aortic dissection represent two distinct pathophysiological entities with regard to late outcome. The need for any kind of intervention in the thoracoabdominal aorta is significantly higher in primary type B aortic dissections. A remaining patent primary entry tear independently predicts the need for intervention (surgery or TEVAR) in patients after surgery for acute type A aortic dissection and, thereby, remains the main target of initial therapy. The thrombosis status of the false lumen seems to be of secondary importance.

Preliminary findings in quantification of changes in septal motion during follow-up of type B aortic dissections

OBJECTIVE

To quantify longitudinal changes in intra-arterial septum (IS) motion with two-dimensional (2D) phase-contrast magnetic resonance imaging (2D pcMRI) in type B aortic dissections (AD) to improve the understanding of AD and its midterm development.

METHODS

From a database of 42 patients who underwent a dynamic magnetic resonance imaging (MRI) examination at the Acute Aortic Treatment Center of The Methodist DeBakey Heart & Vascular Center, 2D pcMRI image data was available from 10 patients with type B AD for both short-term (mean, 6.6 days; range, 1-10 days; n = 7) and midterm follow-up (mean, 155 days; range, 60-324; n = 5). IS motion was quantified as motion of IS boundary points averaged over the cardiac cycle. Relative change in IS motion was expressed as percent change compared with initial presentation. Maximum IS extension (true lumen [TL] expansion) and contraction (TL compression), IS fraction in phase with aortic flow and correlation of IS motion with aortic flow (IS compliance) were quantified.

RESULTS

IS motion at initial presentation was 0.68 ± 0.2 mm and was reduced at short-term (0.48 ± 0.3 mm; P = .07) and midterm (0.5 ± 0.2 mm; P = .1) follow-up. Trend in relative change of IS motion was variable during short-term follow-up: reduced in three subjects (-75% ± 6%) and elevated in four subjects (48% ± 23%). During midterm follow-up, relative change in IS motion was reduced in four subjects (28% ± 19%) and slightly elevated in one (6.2%). IS contraction decreased with follow-up while IS extension slightly increased. Fraction of IS moving in phase with aortic flow increased but IS compliance decreased, suggesting increasing IS stiffness.

CONCLUSIONS

Reduction of IS motion in AD is seen with short-term and midterm follow-up. Intersubject variability of this trend is high at short-term follow-up but low at midterm follow-up. Detailed analysis of IS motion parameters indicate reduction of IS contraction and IS compliance with time. This has potential implications for endovascular management of type B aortic dissections, as expansion of aortic stent grafts can be limited by a stiff IS.

Endovascular treatment of descending thoracic aortic disease: single-center, 15-year experience

PURPOSE

To report the experience with thoracic endovascular aortic repair (TEVAR) in a single center over a 15-year period.

MATERIALS AND METHODS

All patients undergoing TEVAR during the period 1994-2009 were retrospectively evaluated.

RESULTS

The study comprised 133 patients (96 men, age 69.5 years ± 14.7) who underwent 21 emergency and 112 elective TEVAR procedures. Aortic pathologies included 91 aneurysms, 14 pseudoaneurysms, 14 penetrating ulcers with or without pseudoaneurysms or intramural hematomas, 8 type B dissections (3 acute and 5 chronic), and 6 traumatic transections. Technical success was 97.7% with a 30-day mortality of 7.5%. There were 101 patients followed to 1 year, 35 patients followed to 5 years, and 6 patients followed to 10-15 years. The overall estimated survivals at 1 year, 5 years, and 10 years were 81%, 48%, and 36%. The 30-day mortality rates in emergency and elective TEVAR procedures were 23.9% and 4.5% (P = .005). However, among patients who survived > 30 days, there was no significant difference in mortality between groups undergoing emergency and elective TEVAR procedures (P = .9, hazard ratio [HR] 0.94, confidence interval [CI] 0.4-2.2). There was no significant gender survival difference. The 30-day mortality rate in octogenarians (n = 31) was higher than in younger patients (P = .03). Incidences of stroke and paraplegia within 30 days of TEVAR were 6.8% and 2.2%. Endoleaks were found in 39 (29%) patients, and secondary interventions were performed in 6 (4.5%) patients.

CONCLUSIONS

The data support the safety and efficacy of TEVAR for aortic pathologies with a low mortality rate. Younger patients have fewer complications after TEVAR. After the acute perioperative period, TEVAR procedures performed emergently are as durable as the procedures performed electively.

[Treatment of thoracic aortic disease using endovascular stent-grafts: from therapeutic indications to possible complications]

Thoracic endovascular aortic repair (TEVAR) is a minimally invasive technique which is increasingly used in different thoracic aortic pathologies such as aortic aneurysm, complicated type B aortic dissection, aortic trauma, intramural hematoma and penetrating aortic ulcer. In this paper we discuss the main indications for endovascular stent-grafts in the treatment of thoracic aortic disease, based on three cases in which this procedure was used for three different conditions: degenerative aneurysm, complicated type B dissection and post-traumatic injury. These case reports add to the evidence that TEVAR is a safe and feasible therapeutic alternative in selected patients with thoracic aortic disease, improving aortic remodeling, with relatively low morbidity and mortality. The main complications and difficulties related to the procedure are also discussed.

Endovascular stent-graft placement or open surgery for the treatment of acute type B aortic dissection: a meta-analysis

BACKGROUND

Acute type B aortic dissection (ATBAD) is a life-threatening condition. Open chest surgical repair using a prosthetic graft has been a conventional treatment for ATBAD. During the past decade, thoracic endovascular aortic repair (TEVAR), which is considered as a less invasive and potentially safer technique, has been increasingly used to treat this condition. Evidence is needed to support the use of TEVAR for these patients. The aim of this review was to assess the efficacy of TEVAR versus conventional open surgery in patients with ATBAD.

METHODS

For this review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (last searched: 2010, issue 4), MEDLINE, EMBASE, CINAHL, Web of Science, and the Chinese Biomedicine Database for clinical trials until January 18, 2011. Controlled trials in which patients with ATBAD were assigned to TEVAR or open surgical repair were included. For each outcome, we evaluated the quality of the evidence with reference to the Grading of Recommendations Assessments, Development, and Evaluation criteria. At the end, we used RevMan 5.0 software to analyze the datum.

RESULTS

Five trials (318 participants) are included in this review. As determined by the Grading of Recommendations Assessments, Development, and Evaluation approach, the result quality was low for 30-day mortality and very low for other variables. TEVAR can significantly reduce the short-term mortality for ATBAD (Mantel-Haenszel fixed odds ratio [95% confidence interval]: 0.19 [0.09-0.39], P < 0.001). TEVAR cannot significantly improve postoperative complications or long-term mortality.

CONCLUSIONS

TEVAR can be weakly recommended as an alternative for the selective treatment of ATBAD but cannot always be used in case of surgery.

Type-selective benefits of medications in treatment of acute aortic dissection (from the International Registry of Acute Aortic Dissection [IRAD])

The effects of medications on the outcome of aortic dissection remain poorly understood. We sought to address this by analyzing the International Registry of Acute Aortic Dissection (IRAD) global registry database. A total of 1,301 patients with acute aortic dissection (722 with type A and 579 with type B) with information on their medications at discharge and followed for ≤5 years were analyzed for the effects of the medications on mortality. The initial univariate analysis showed that use of β blockers was associated with improved survival in all patients (p = 0.03), in patients with type A overall (p = 0.02), and in patients with type A who received surgery (p = 0.006). The analysis also showed that use of calcium channel blockers was associated with improved survival in patients with type B overall (p = 0.02) and in patients with type B receiving medical management (p = 0.03). Multivariate models also showed that the use of β blockers was associated with improved survival in those with type A undergoing surgery (odds ratio 0.47, 95% confidence interval 0.25 to 0.90, p = 0.02) and the use of calcium channel blockers was associated with improved survival in patients with type B medically treated patients (odds ratio 0.55, 95% confidence interval 0.35 to 0.88, p = 0.01). In conclusion, the present study showed that use of β blockers was associated with improved outcome in all patients and in type A patients (overall as well as in those managed surgically). In contrast, use of calcium channel blockers was associated with improved survival selectively in those with type B (overall and in those treated medically). The use of angiotensin-converting enzyme inhibitors did not show association with mortality.

Endovascular approaches and perioperative considerations in acute aortic dissection

Aortic dissections remain complicated management issues both in the acute setting and in the chronic setting. Acute problems revolve around malperfusion syndromes or rupture, whereas chronic issues progress from the development of aneurysms in the residual dissected aorta. Endovascular approaches to dealing with these difficult situations are being used more frequently to treat acute issues in type B dissections and prevent secondary complications in type A dissections that may require significant intervention in the future. This article discusses the endovascular approaches employed in the care of acute dissections with particular attention toward the anesthetic considerations involved in these challenging cases.

Volumetric analysis of type B aortic dissections treated with thoracic endovascular aortic repair

BACKGROUND

Type B aortic dissections are being successfully treated by thoracic endovascular aortic repair (TEVAR). Postoperative false lumen patency has been associated with aneurysmal dilatation and rupture of the thoracic aorta, necessitating further intervention. This is the first volumetric analysis of type B aortic dissections comparing patients with and without false lumen thrombosis (FLT) after TEVAR. We hypothesized that a greater increase in postoperative true lumen volume will lead to FLT, and without this change, false lumen patency will result.

METHODS

Preoperative and postoperative computed tomography angiography (CTA) imaging was analyzed using three-dimensional reconstruction to measure the short- and long-axis diameter and cross-sectional area of the true lumen, false lumen, and total aorta. Measurements were taken at 5-cm intervals from the left subclavian artery to the aortic bifurcation. Pre- and postoperative volumetric data were calculated and compared in patients with and without postoperative FLT.

RESULTS

Between 2006 and 2010, 132 patients underwent thoracic aortic stent grafting. Of these, 31 (23%) had thoracic endografting for type B aortic dissection. Pre- and postoperative CTA images were available for analysis in 23 patients with a mean age of 59 ± 14 years treated for acute, complicated (n = 8, 35%), and chronic (n = 15, 65%) indications. Mean follow-up imaging was 9 months (range, 1-39 months). Thirteen patients (56%) had postoperative FLT and 10 (43%) had persistent false lumen patency. The dissections involved the left subclavian artery (n = 12), visceral arteries (n = 14), renal arteries (n = 16), and iliac arteries (n = 15). The left subclavian artery was intentionally covered in 15 patients (65%). There were no significant differences in age, acute vs chronic dissection, branch vessel involvement, coverage of the left subclavian artery, or distal extent of the endograft between patients with and without postoperative FLT. Patients with postoperative FLT had a significantly smaller preoperative maximum thoracic aortic diameter (5.05 ± 1.0 vs 6.30 ± 1.4 cm; P = .02). Volumetric analysis demonstrated significantly smaller preoperative true lumen volume (141.3 ± 68 vs 230.5 ± 92 cm(3); P = .01) in patients with FLT, but no difference in preoperative false lumen volume. Patients with FLT had a significant increase in the volume percentage of the true lumen from 42.7% to 61.7% (P = .02) after stent graft repair, compared with an increase from 46.7% to 47.7% (P = .75) in patients with persistent false lumen patency.

CONCLUSIONS

This volumetric study of type B aortic dissection treated with TEVAR suggests that the ability of the endograft to significantly increase the true lumen volume as a percent of the total aorta most accurately predicts postoperative FLT. This is best demonstrated in a nonaneurysmal dissection regardless of timing since dissection.

A systematic review of mid-term outcomes of thoracic endovascular repair (TEVAR) of chronic type B aortic dissection

OBJECTIVE AND DESIGN

The role of Thoracic Endovascular Repair (TEVAR) in chronic type B aortic dissection remains controversial and its mid-term success as an alternative to open repair or best medical therapy remains unknown. The aim of the present study was to provide a systematic review of mid-term outcomes of TEVAR for chronic type B aortic dissection.

MATERIALS AND METHODS

Medline, trial registries, conference proceedings and article reference lists from 1950 to January 2011 were searched to identify case series reporting mid-term outcomes of TEVAR in chronic type B dissection. Data were extracted for review.

RESULTS

17 studies of 567 patients were reviewed. The technical success rate was 89.9% (range 77.6-100). Mid-term mortality was 9.2% (46/499) and survival ranged from 59.1 to 100% in studies with a median follow-up of 24 months. 8.1% of patients (25/309) developed endoleak, predominantly type I. Re-intervention rates ranged from 0 to 60% in studies with a median follow-up of 31 months. 7.8% of patients (26/332) developed aneurysms of the distal aorta or continued false lumen perfusion with aneurysmal dilatation. Rare complications included delayed retrograde type A dissection (0.67%), aorto-oesophageal fistula (0.22%) and neurological complications (paraplegia 2/447, 0.45%; stroke 7/475, 1.5%).

CONCLUSION

The absolute benefit of TEVAR over alternative treatments for chronic B-AD remains uncertain. The lack of natural history data for medically treated cases, significant heterogeneity in case selection and absence of consensus reporting standards for intervention are significant obstructions to interpreting the mid-term data. High-quality data from registries and clinical trials are required to address these challenges.

Management of acute aortic syndromes

Acute aortic syndrome (AAS) is a modern term to describe interrelated emergency aortic conditions with similar clinical characteristics and challenges. These conditions include aortic dissection, intramural haematoma (IMH), and penetrating atherosclerotic ulcer (PAU and aortic rupture); trauma to the aorta with intimal laceration may also be considered. The common denominator of AAS is disruption of the media layer of the aorta with bleeding within IMH, along the aortic media resulting in separation of the layers of the aorta (dissection), or transmurally through the wall in the case of ruptured PAU or trauma. Population-based studies suggest that the incidence of acute dissection ranges from 2 to 3.5 cases per 100 000 person-years; hypertension and a variety of genetic disorders with altered connective tissues are the most prevalent risk conditions. Patients with AAS often present in a similar fashion, regardless of the underlying condition of dissection, IMH, PAU, or contained aortic rupture. Pain is the most commonly presenting symptom of acute aortic dissection and should prompt immediate attention including diagnostic imaging modalities (such as multislice computed tomography, transoesophageal ultrasound, or magnetic resonance imaging). Prognosis is clearly related to undelayed diagnosis and appropriate surgical repair in the case of proximal involvement of the aorta; affection of distal segments of the aorta may call for individualized therapeutic approaches favouring endovascular in the presence of malperfusion or imminent rupture, or medical management.

Diagnosis and management issues in thoracic aortic aneurysm

Thoracic aortic enlargement is an increasingly recognized condition that is often diagnosed on imaging studies performed for unrelated indications. The risk of unrecognized and untreated aortic enlargement and aneurysm includes aortic rupture and dissection which carry a high burden of morbidity and mortality. The etiologies underlying thoracic aortic enlargement are diverse and can range from degenerative or hypertension associated aortic enlargement to more rare genetic disorders. Therefore, the evaluation and management of these patients can be complex and requires knowledge of the pathophysiology associated with thoracic aortic dilation and aneurysm. Additionally, there have been important advances in the treatment available to patients with thoracic aortic disease, including an increased role of endovascular therapy. Given the risk of mortality, increased clinical recognition and advances in therapeutics, the American College of Cardiology, American Heart Association and related professional societies have recently published guidelines on the management of thoracic aortic disease. This review focuses on the pathophysiology and various etiologies that lead to thoracic aortic aneurysm along with the diagnostic modalities and management of asymptomatic patients with thoracic aortic disease.

Management of acute complicated and uncomplicated type B dissection of the aorta: focus on endovascular stent grafting

Endovascular repair of aortic dissection is the subject of multiple studies. This article aims to review the current literature on Type B complicated and uncomplicated dissection, including indications for medical therapy, open surgical therapy, and endovascular therapy. The review suggests a benefit for thoracic endovascular aortic repair in complicated dissection and medical therapy for uncomplicated dissection. Upcoming trials may shed more light on this issue.

Heat shock proteins as biomarkers for the rapid detection of brain and spinal cord ischemia: a review and comparison to other methods of detection in thoracic aneurysm repair

The heat shock proteins (HSPs) are members of highly conserved families of molecular chaperones that have multiple roles in vivo. We discuss the HSPs in general, and Hsp70 and Hsp27 in particular, and their rapid induction by severe stress in the context of tissue and organ expression in physiology and disease. We describe the current state of knowledge of the relationship and interactions between extra- and intracellular HSPs and describe mechanisms and significance of extracellular expression of HSPs. We focus on the role of the heat shock proteins as biomarkers of central nervous system (CNS) ischemia and other severe stressors and discuss recent and novel technologies for rapid measurement of proteins in vivo and ex vivo. The HSPs are compared to other proposed small molecule biomarkers for detection of CNS injury and to other methods of detecting brain and spinal cord ischemia in real time. While other biomarkers may be of use in prognosis and in design of appropriate therapies, none appears to be as rapid as the HSPs; therefore, no other measurement appears to be of use in the immediate detection of ongoing severe ischemia with the intention to immediately intervene to reduce the severity or risk of permanent damage.

Ascending thoracic aorta dimension and outcomes in acute type B dissection (from the International Registry of Acute Aortic Dissection [IRAD])

It is not well known if the size of the ascending thoracic aorta at presentation predicts features of presentation, management, and outcomes in patients with acute type B aortic dissection. The International Registry of Acute Aortic Dissection (IRAD) database was queried for all patients with acute type B dissection who had documentation of ascending thoracic aortic size at time of presentation. Patients were categorized according to ascending thoracic aortic diameters ≤4.0, 4.1 to 4.5, and ≥4.6 cm. Four hundred eighteen patients met inclusion criteria; 291 patients (69.6%) were men with a mean age of 63.2 ± 13.5 years. Ascending thoracic aortic diameter ≤4.0 cm was noted in 250 patients (59.8%), 4.1 to 4.5 cm in 105 patients (25.1%), and ≥4.6 cm in 63 patients (15.1%). Patients with an ascending thoracic aortic diameter ≥4.6 cm were more likely to be men (p = 0.01) and have Marfan syndrome (p <0.001) and known bicuspid aortic valve disease (p = 0.003). In patients with an ascending thoracic aorta ≥4.1 cm, there was an increased incidence of surgical intervention (p = 0.013). In those with an ascending thoracic aorta ≥4.6 cm, the root, ascending aorta, arch, and aortic valve were more often involved in surgical repair. Patients with an ascending thoracic aorta ≤4.0 were more likely to have endovascular therapy than those with larger ascending thoracic aortas (p = 0.009). There was no difference in overall mortality or cause of death. In conclusion, ascending thoracic aortic enlargement in patients with acute type B aortic dissection is common. Although its presence does not appear to predict an increased risk of mortality, it is associated with more frequent open surgical intervention that often involves replacement of the proximal aorta. Those with smaller proximal aortas are more likely to receive endovascular therapy.

How to manage the left subclavian artery during endovascular stenting for thoracic aortic dissection? An assessment of the evidence

BACKGROUND

Despite the publication of recent guidelines for management of the left subclavian artery (LSA) during endovascular stenting procedures of the thoracic aorta, specific management for those presenting with dissection remains unclear. This systematic review attempts to address this issue.

METHODS

Systematic assessment of the published data on thoracic aorta dissection was performed identifying 46 studies, which incorporated 1,275 patients. Primary outcomes included the prevalence of left arm ischemia, stroke, spinal cord ischemia, endoleak, stent migration, and mortality. Outcomes were compared between patients with and without LSA coverage and revascularization incorporating factors such as the number of stents used, length of aorta covered, urgency of intervention, and type of dissection (acute or chronic). Statistical pooling techniques, χ(2) tests, and Fisher's exact testing were used for group comparisons.

RESULTS

As compared with other outcomes, LSA coverage without revascularization in the presence of aortic dissection is much more likely to be complicated by left arm ischemia (prevalence increased from 0.0% to 4.0% [p = 0.021]), stroke (prevalence increased from 1.4% to 9.0% [p = 0.009]), and endoleak (prevalence increased from 4.0% to 29.3% [p = 0.001]). However, revascularization was not shown to reverse these effects. Longer aortic coverage (≥ 150 mm) was associated with an increased prevalence of spinal cord ischemia (from 1.3% to 12.5% [p = 0.011]) and mortality (from 1.3% to 15.6% [p = 0.003]).

CONCLUSION

In patients undergoing endovascular stenting for thoracic aortic dissection, in cases where LSA coverage is necessary, revascularization should be considered before the procedure to avoid complications such as left arm ischemia, stroke, and endoleak, and where feasible, an appropriate preoperative assessment should be carried out.

[Acute aortic syndrome and endovascular treatment: good indications of stent-graft, stent and aortic fenestration]

Acute aortic syndrome of the descending aorta can be treated with stent-graft thanks to technical and material development. Ruptured aneurysms, aortic dissection, wall hematoma and penetrating ulcers can be treated with stent-graft. According to the type of initial lesion, and the clinical tolerance, the emergency of treatment can be different. Non covered stent and aortic fenestration are used in case of visceral ischemia in aortic dissection, according to the type of ischemia.