TEVAR and covering the celiac artery. Is it safe or not?

Thoracic endovascular aortic repair (TEVAR) is the treatment of choice for descending thoracic aortic aneurysms (TAA). However, not all patients with TAA can be treated with the endovascular technique. Insufficient proximal and/or distal sealing zone is the most common reason for open surgery in these patients. If the distal sealing zone above the celiac axis is too short, several endovascular alternatives are possible; hybrid procedures with TEVAR and open by-pass to the celiac artery, custom made stent-grafts with scallop or fenestration for the celiac artery, or intentional coverage of the celiac artery. In the latter case, adequate collateral supply to the upper gastrointestinal tract is crucial. Collateral arteries joining the celiac and the superior mesenteric arteries are well characterized in patients with chronic celiac stenosis or occlusion. Are these collateral pathways sufficient also for sudden iatrogenic closure of the celiac artery? By performing a preoperative angiography of the superior mesenteric artery with temporary balloon occlusion of the celiac artery, collateral capacity between the two vessels can be tested in advance. Exact positioning of the distal end of a large thoracic stent-graft can be challenging and require special considerations and techniques. Most case series in the literature support the efficacy and the safety of intentional celiac covering. However, there are also reports of ischemic foregut complications that could be associated to the procedure. Taken together, in the large majority of patients, it appears that intentional celiac coverage can be done safely provided that sufficient collateral function have been demonstrated in advance.

[Causes of reoperations and their outcomes in patients with the Marfan's syndrome after correction of the ascending aorta aneurysm and aortic insufficiency]

Aim of the study was to elucidate causes of repeat operations and their outcomes in patients with the Marfan's syndrome. Between December 1972 and January 2009 60 patients with Marfan's syndrome were operated for aneurysm of the ascending aorta and aortic insufficiency. All patients were subjected to ascending aorta and aortic valve replacement with valve containing conduit. Five of 60 patients (8.3%) were subjected to 7 repeat operations (2 patients were reoperated twice). Causes of repeat interventions were: conduit dysfunction (n=3), abdominal aortic aneurysm (n=3), mitral valve prolapse (n=1). Three patients died: 2 during surgery because of impaired conduit function, one - in 1 year after repeat operation of mitral valve replacement for mitral valve prolapse with pronounced mitral insufficiency. In all cases cause of death was progressive heart failure. As an example a case of a female patient who had been subjected to repetitive surgeries because of malfunctioning conduit is presented in this paper. Main reason for reoperations was the Marfan's syndrome itself. Progression of this disease might continue after operation, alteration of the aortic wall promote dissection in regions not subjected to prosthetics. Application of prostheses especially designed for replacement of the ascending aorta excludes such causes of reoperations and death as disruption of old sutured of two parts conduits.

The use of dynamic volumetric CT angiography (DV-CTA) for the characterization of endoleaks following fenestrated endovascular aortic aneurysm repair (f-EVAR)

Accurate endoleak classification is essential following fenestrated endovascular aneurysm repair (f-EVAR). Both endoleak type and exact source of endoleak have implications upon the urgency and complexity of future management strategies. Herein we report on a patient with a documented endoleak post-f-EVAR, in which the source of blood flow into the aneurysm sac could not be determined using conventional computed tomographic angiography. Consequently, dynamic volumetric computed tomographic angiography (DV-CTA) was employed, which clearly illustrated the site of origin of the endoleak. DV-CTA enables accurate endoleak characterization following f-EVAR, with excellent conspicuity of the source of blood flow into the aneurysm sac.

Acute aortic syndromes and thoracic aortic aneurysm

Acute and chronic aortic diseases have been diagnosed and studied by physicians for centuries. Both the diagnosis and treatment of aortic diseases have been steadily improving over time, largely because of increased physician awareness and improvements in diagnostic modalities. This comprehensive review discusses the pathophysiology and risk factors, classification schemes, epidemiology, clinical presentations, diagnostic modalities, management options, and outcomes of various aortic conditions, including acute aortic dissection (and its variants intramural hematoma and penetrating aortic ulcers) and thoracic aortic aneurysms. Literature searches of the PubMed database were conducted using the following keywords: aortic dissection, intramural hematoma, aortic ulcer, and thoracic aortic aneurysm. Retrospective and prospective studies performed within the past 20 years were included in the review; however, most data are from the past 15 years.

[Is local prosthetics of descending thoracic aorta by its distal dissection effective?]

12 patients with distal aortic dissection were included in the study. All had aortic prosthetics and hemodynamic correction. 6 patients (1st group) had hemodynamic correction type I - Cutdown of the false aortic canal and guiding the blood flow to the correct canal. The rest 6 (2nd group) hemodynamic correction type II was performed (guiding blood flow to the both aortic channels). 83,3% of patients of the 1st group demonstrated the false aortic channel thrombosis up to the level of visceral branches, the rest 33,3% of patients had total thrombosis of the false channel. All patients of the 2nd group demonstrated maintenance of the blood flow in both channels, which leaves risk of further aortic dilatation and rupture.

Repeated true lumen collapse after repair of descending thoracic aneurysm in chronic type B dissection

The patient was 69-year-old man. Dilatation of the descending thoracic aorta in chronic type B dissection was revealed on computed tomography. During replacement of the descending thoracic aorta, distal anastomosis was performed in a double-barreled manner. On postoperative day (POD) 3, the patient complained of paralysis and dysesthesia of both legs, and he developed acute renal dysfunction. Based on the results of emergent aortography, we suspected true lumen collapse resulting from an expanded false lumen; therefore, we stabilized the intimal flap to the aortic wall. However, on POD 7 he complained of coldness in both legs. Emergent aortography revealed that occlusion of the abdominal aorta had recurred, and so right axillobifemoral bypass was performed. Preoperative conventional angiography may be mandatory to confirm reentry. There have been several reports of transcatheter fenestration in acute or chronic aortic dissection. The technique would also be effective for postoperative malperfusion.

The role of the renin-angiotensin system in aortic aneurysmal diseases

The renin-angiotensin system has been invoked in the development of both abdominal and thoracic aortic aneurysms. This has been demonstrated experimentally by the chronic subcutaneous infusion of angiotensin II, which consistently leads to development of abdominal aortic aneurysms (AAAs) in mice. Angiotensin II-induced AAAs have highly heterogenous cellular and extracellular matrix characteristics throughout the aorta that change markedly with infusion duration. The mechanistic basis for the reproducible location of AAA development has not been elucidated, but many insights have been provided, especially regarding receptor and inflammatory mechanisms. A recent clinical study provided limited evidence for extrapolating these results to mechanisms of human AAAs. Experimental evidence has also demonstrated that antagonism of angiotensin II type 1 (AT1) receptors prevents ascending aortic aneurysms in a murine model of Marfan's syndrome. A clinical study is currently ongoing to demonstrate the efficacy of AT1 receptor antagonism in humans.

Screening for thoracoabdominal aortic aneurysms in patients with aortoiliac atherosclerosis: a preliminary study

Thoracoabdominal aortic aneurysms (TAAs) usually present with rupture and carry a high morbidity and mortality rate. Early detection of TAAs with screening methods and elective surgical repair could potentially diminish these complications. The present study was aimed at screening for TAA in patients with angiography-proven aortoiliac atherosclerosis (n=43). A group of patients without aortoiliac atherosclerosis was used as controls (n=15). Age, sex and aortic diameter at the level of the T12 vertebra were recorded. The subjects were divided into two age categories, the first made up of those aged less than 65 years and the second those aged 65 years or more. A T12 aortic diameter greater than 35 mm was used to indicate TAA. Statistical analyses were performed by independent t-test and general linear model with age category, sex and atherosclerosis as factors. The mean T12 aortic diameters were greater in patients with atherosclerosis than in the control group (25.2+/-5.0 vs. 22.9+/-2.4 mm; p=0.034). Two out of 43 patients (4.7%) with aortoiliac atherosclerosis had TAA, while no one in the control group had TAA. A general linear model showed that the interaction of age category and sex significantly affected the T12 aortic diameter [F (1.49)=4.044, p=0.050]. Post hoc (LSD) tests revealed that male patients aged over 65 had greater T12 aortic diameters than other patients. We conclude that patients with aortoiliac atherosclerosis may be at greater risk for developing TAA. Ageing and male sex may also be associated with thoracoabdominal aortic enlargement.

The value of motor evoked potentials in reducing paraplegia during thoracoabdominal aneurysm repair

OBJECTIVE

Paraplegia after thoracoabdominal aortic aneurysm (TAAA) repair mainly occurs in patients with Crawford extent I and II. We assessed the impact of monitoring spinal cord integrity and the subsequent adjusted surgical maneuvers on neurologic outcome in repairs of type I and II TAAAs.

METHODS

Surgical repair of TAAAs was performed in 112 consecutive patients with extent type I (n = 42) and type II (n = 70) aneurysms. The surgical protocol included cerebrospinal fluid drainage, moderate hypothermia, and left heart bypass with selective organ perfusion. Spinal cord function was assessed by means of monitoring motor evoked potentials (MEPs). Significant decreased MEPs always generated adjustments, including raising distal aortic and mean arterial pressure, reattachment of visible intercostal arteries, or endarterectomy of the excluded aortic segment with revascularization of back bleeding intercostal arteries.

RESULTS

Motor evoked potential monitoring could be achieved in all patients. By maintaining a mean distal aortic pressure of 60 mm Hg, MEPs were adequate in 82% of patients. Increasing distal aortic pressure restored MEPs in all patients. In 19 patients (17%), MEPs decreased significantly during aortic cross-clamping because of critical spinal cord ischemia. MEPs returned in all patients after spinal cord blood flow was re-established except in three patients with type II TAAA in whom MEPs could not be restored, and absent MEPs at the end of the procedure corresponded with neurologic deficit. Delayed paraplegia developed in two patients owing to hemodynamic instability with insufficient mean arterial blood pressure to maintain adequate spinal cord perfusion.

CONCLUSION

Monitoring MEPs is a highly reliable technique to assess spinal cord ischemia during TAAA repair. A surgical protocol including cerebrospinal fluid drainage, left heart bypass, and monitoring of MEPs can reduce the paraplegia rate significantly. Adjusted hemodynamic and surgical strategies induced by changes in MEPs could restore spinal cord ischemia in most patients, preventing early and late paraplegia in all type I patients. In type II patients, early paraplegia occurred in 4.2% and delayed neurologic deficit in 2.9%. Despite all available measures, complete prevention of paraplegia in type II aneurysms seems to be unrealistic.

[Simulation of stent treatment for aneurysms in the inner bend of aortic arch]

Endovascular stent is a new technique for the treatment of aortic arch aneurysms. The present simulation study of endovascular stent treatment for aneurysms in the inner bend of aortic arch is initiated by the fact that no one has ever investigated the hemodynamics of stented aortic arch aneurysm harboring a bleb. For the comparative convenience, a stented and a nonstented aortic arch aneurysm models were constructed respectively. Physiological blood flows in both models were simulated using the computational fluid dynamics method. The detailed flow patterns, pressure and wall shear stress distributions around the aneurysm of both models were compared and analyzed so as to evaluate the effectiveness of endovascular stent treatment for aortic arch aneurysms. Results showed that the stented model is attributed to substantially different intra-aneurysmal flow patterns versus the nonstented model. Flow activities within the stented aneurysmal sacs are markedly diminished, specifically the pressure and wall shear stress in the bleb were significantly decreased. These phenomena allow us to conclude that endovascular stent can promote intra-aneurysmal thrombus development and attenuating aneurysm rupture risk.

The Use of an Extra-corporeal Graft to Maintain Cerebral Perfusion During Thoracic Endovascular Aneurysm Repair

Endovascular access for aneurysm repair can be challenging in patients with iliofemoral occlusive disease. The carotid artery is an alternative access site, but may increase the risk of cerebral hypoperfusion during stent delivery. We describe a novel approach, where temporary extra-corporeal bypass was used to maintain cerebral perfusion during endovascular thoracic aneurysm repair via the carotid artery, in a patient with significant aorto-iliac and arch vessel disease.

Loss of elastic fiber integrity and reduction of vascular smooth muscle contraction resulting from the upregulated activities of matrix metalloproteinase-2 and -9 in the thoracic aortic aneurysm in Marfan syndrome

Thoracic aortic aneurysm (TAA) is the life-threatening complication of Marfan syndrome (MFS), a connective tissue disorder caused by mutations in the fibrillin-1 gene. TAA is characterized by degradation of elastic fiber, suggesting the involvement of matrix metalloproteinase (MMP)-2 and -9, the activation of which is regulated by TIMP (tissue inhibitor of MMP) types 1 and 2. We hypothesized that MMP-2 and -9 were upregulated during TAA formation in Marfan syndrome, causing loss of elastic fibers and structural integrity. We studied mice, from 3 to 12 months, heterozygous for a mutant Fbn1 allele encoding a cysteine substitution in fibrillin-1 (Fbn1(C1039G/+), designated as "Marfan" mice) (n=120), the most common class of mutation in Marfan syndrome. The littermates, Fbn1(+/+) served as controls (n=120). In Marfan aneurysmal thoracic aorta, mRNA and protein expression of MMP-2 and -9 were detected at 3 months and peaked at 6 months of age, accompanied by severe elastic fiber fragmentation and degradation. From 3 to 9 months, the MMP-2/TIMP-2 ratio increased by 43% to 63% compared with the controls. Dilated thoracic aorta demonstrated increased elasticity but distention caused a pronounced loss of contraction, suggesting weakening of the aortic wall. Breaking stress of the aneurysmal aorta was 70% of the controls. Contraction in response to depolarization and receptor stimulation decreased in the aneurysmal thoracic aorta by 50% to 80%, but the expression of alpha-smooth muscle actin between the 2 strains was not significantly different. This report demonstrates the upregulation of MMP-2 and -9 during TAA formation in Marfan syndrome. The resulting elastic fiber degeneration with deterioration of the aortic contraction and mechanical properties may explain the pathogenesis of TAA.

Aortic debranching procedures to facilitate endografting

Since approval of the Gore TAG device in 2005, endo-grafting of isolated descending thoracic aneurysms has been a welcome replacement to open surgery by many vascular and cardiac surgeons. Obvious constraints of this new technology are seal zones relative to adjacent brachiocephalic and visceral vessels. This is particularly important with regard to the more extensive thoracoabdominal aortic aneurysms. Although branched or fenestrated stent grafts have been used for such cases, these technically advanced devices are not available for general use and, therefore, many practitioners are left with few alternatives other than standard open repair. Some centers have tinkered with various forms of extra-anatomic bypass to lengthen seal zone sites and facilitate stent graft repair. The lack of uniformity and long-term data hamper acceptance of this approach. This review attempts to cull all available information on this technique from recent case reports and series published in the literature.

Bilateral axillary artery inflow in the treatment of a rare case of pseudocoartaction of the aortic arch

The axillary artery is the preferred site for arterial cannulation in operations for ascending aorta and aortic arch replacement in order to reduce perfusion-related morbidity in acute dissection and to prevent cerebral embolism in atherosclerotic aneurysm. We present the case of a patient with a chronic dissection presenting as pseudocoarctation of the aortic arch in which bilateral axillary artery inflow was necessary to perfuse both ascending and descending aorta.

Novel Way to Confirm Successful Endovascular Repair of a Thoracic Aortic Aneurysm Using a Remote Wireless Pressure Sensor

Due to the continuous risk of rupture from endoleaks after endoluminal graft repair of thoracic aneurysms, the need for lifelong postoperative surveillance has become necessary. Patients are put at a lifetime risk of radiation exposure and may be at an increased risk of contrast induced nephropathy from routine contrast use during follow-up computed tomography for postoperative surveillance of endoluminal grafts. Measuring aneurysm sac pressures using remote wireless pressure sensor may provide a noninvasive method to detect endoleak, procedural success, and long-term stent graft stability.

Cross-Sectional Imaging Studies: What Can We Learn and What Do We Need to Know?

Rapid, noninvasive imaging approaches can provide novel diagnostic information and, when effectively interpreted and implemented in a therapeutic strategy, can simplify procedures. Endovascular therapy of thoracic and abdominal aortic disease represents a dramatic shift in treatment of thoracoabdominal aortic disease, but one that requires a change in the knowledge base regarding both the morphology and pathophysiology of aortic disease and the interaction with interventional devices. As a result, the demands on cross-sectional imaging have increased commensurately with the complexity of the therapeutic options, but advances in cross-sectional imaging have kept pace. Current computed tomography (CT) and magnetic resonance imaging (MRI) technologies provide detailed morphologic assessment, and are advancing rapidly into more sophisticated physiologic evaluation of aortic disease. These advances may more effectively triage patients to appropriate therapy, or exclude patients from unnecessary invasive procedures. The information gleaned from CT and MRI studies is critical for the vascular surgeon who wants to identify appropriate vascular territories for intervention, plan a detailed approach, and develop sophisticated surveillance strategies.

Effectiveness of intensive medical therapy in type B aortic dissection: A single-center experience

OBJECTIVE

Although the mainstay of managing acute descending thoracic aortic dissection (ADTAD) remains medical, certain patients will require emergency surgery for complications of rupture or ischemia. This study evaluates factors that affect outcome and determines which patients previously treated surgically would have been eligible for endovascular repair.

METHODS

A single-institution retrospective study was conducted of patients who presented with clinical signs of ADTAD that was confirmed by magnetic resonance angiography (MRA) or computed tomography (CT). All patients were admitted to the intensive care unit (ICU) and medically managed to maintain systolic blood pressure<120 mm Hg and heart rate<70 beats/min. Two treatment groups were identified: group 1 received medical treatment only; group 2 received medical treatment plus emergency surgery. Patient demographic and clinical data were correlated with 30-day group mortality and morbidity and need for emergency surgery. The MRA and CT scan images of group 2 were retrospectively reviewed to determine if currently available endovascular treatment could have been done. The Fisher exact test was used to compare between the groups, and P<.05 was considered significant.

RESULTS

Between 1991 and 2005, 83 patients (55 men) were treated for ADTAD. The mean age was 67 years (range, 38 to 85). Sixty-eight patients (82%) had hypertension, three (3.6%) had Marfan syndrome, and 51 (62%) were smokers. Twenty-five (32%) of the patients were receiving beta-blocker therapy before the onset of their symptoms. Back pain was the most common initial symptom (72.2%). Emergency surgery was required in 19 patients (23%): 12 for rupture or impending rupture, four for mesenteric ischemia, and three for lower extremity ischemia. The need for emergency surgery was significantly higher in smokers (P=.03), in patients>70 years old (P=.035), and in patients who were not receiving beta-blocker therapy before the onset of symptoms (P=.023). The combined overall morbidity rate was 33%, and the mortality rate was 9.6%. Morbidity in group 2 was 64% and significantly higher than the 23% in group 1 (P=.00227). The mortality rate was also higher in group 2 at 31.5% compared with group 1 at 1.6% (P=.0004). Factors affecting the overall mortality included age>70 years (P=.057), previous abdominal aortic aneurysm repair (P=.018), tobacco use (P=.039), and the presence of leg pain at initial presentation (P=.013). As determined from the review of radiologic data, 11 of 13 patients with scans available for review in group 2 could have been treated with currently available endovascular grafts.

CONCLUSIONS

Intensive medical therapies are effective in preventing early mortality associated with ADTAD. Predictably, the need for emergency surgery carries a high morbidity and mortality rate. Most patients in this series requiring emergency surgery could have been candidates for endovascular therapy had it been available.

Hybrid approach to thoracoabdominal aortic aneurysms in patients with prior aortic surgery

OBJECTIVE

The hybrid approach to the repair of thoracoabdominal aortic aneurysm (TAAA), consisting of visceral aortic debranching with retrograde revascularization of the splanchnic and renal arteries and aneurysm exclusion using stent grafts, has been previously described and may be considered particularly appealing in high-risk patients, especially those who have undergone prior aortic surgery. This study analyzed prospectively recorded data of a series of high-risk patients with prior aortic surgery who underwent hybrid TAAA repair at our institute and contrasted the outcomes with those of a similar group of patients who underwent conventional open TAAA repair.

METHODS

Between 2001 and 2006, 13 patients (12 men) with a median age of 69.6 years (range, 35 to 82 years) underwent one-stage hybrid repair of TAAA (7 type I, 2 type II, 2 type IV, and 2 aneurysms of the visceral aortic patch). These patients, the hybrid group, had a history of aortic surgery (30.7% ascending, 30.7% descending, 46.1% abdominal aortic repair, and 15.4% redo TAAA) and were at high risk for open repair. The criteria used to define these patients as high risk and to indicate the need for hybrid treatment were American Society of Anesthesiologists (ASA) class 3 or 4 associated with a preoperative forced expiratory volume in 1 second (FEV1)<50%. In all cases, we accomplished partial or total visceral aortic debranching through (1) a previous visceral artery retrograde revascularization with synthetic grafts (single bypass, customized Y or bifurcated grafts), and (2) aortic endovascular repair with one of three different commercially produced stent grafts (Cook, W.L. Gore & Assoc, and Medtronic). We analyzed the results and compared the outcomes of the hybrid group with those of a similar group of 29 patients (25 men) with a median age 65.3 years (range, 58 to 79) selected from our overall series of 246 TAAA repairs between 1988 and 2005. These 29 patients, the conventionally treated group, were selected for having had aortic surgery (22% ascending, 38% descending, 42% abdominal aortic repair, and 10.3% redo TAAA), an ASA 3 or 4, a preoperative FEV1<50%, and a conventional open repair of TAAA (10 type I, 5 type II, 4 type III, 7 type IV, and 3 aneurysms of the visceral aortic patch).

RESULTS

In the hybrid group, 32 visceral bypasses were completed and endovascular TAAA repair was successful in all cases. No intraoperative deaths occurred. Perioperative mortality was 23%, and morbidity was 30.8% (renal failure in 2, respiratory failure in 1, and delayed transient paraplegia in 1). At a median follow-up of 14.9 months (range, 11 days to 59.4 months), all grafts were patent at postoperative computed tomography angiography and no aneurysm-related deaths, endoleak, stent graft migration, or morbidity related to visceral revascularization had occurred. No conventionally treated patients died intraoperatively. Perioperative mortality was 17.2% and morbidity was 44.8% (respiratory failure in 7, coagulopathy in 1, renal failure in 2, and paraplegia in 3). At a median follow-up of 5.4 years (range, 1.7 to 7.9 years), no significant complications related to aortic repair occurred, except for three patients (10.3%) with asymptomatic dilatation of the visceral aortic patch<5 cm undergoing radiologic surveillance.

CONCLUSION

Hybrid TAAA repair is technically feasible in selected cases. Perioperative morbidity and mortality were considerable in our subset of high-risk patients with prior aortic surgery, but no aneurysm-related or procedure-related complications were reported at mid-term follow-up. Hybrid TAAA repair did not lead to a significant improvement in outcomes compared with open TAAA repair in a similar group of patients. Larger series are required for valid statistical comparisons and longer follow-ups are necessary to evaluate the durability of hybrid repairs.