R.G.J. Gibbs

Treatment of Complex Aneurysmal Disease with Fenestrated and Branched Stent Grafts

OBJECTIVES To describe our experience of treating juxtarenal (JRAAAs <4mm neck) and thoracoabdominal aortic aneurysms (TAAAs) using fenestrated and branched stent graft technology. DESIGN Prospective single centre experience. METHODS Since 2005, 29 fenestrated/branched procedures have been performed. 15 patients are studied with JRAAAs (n=7; median neck length 0mm (IQR 0-3.8)) or TAAAs (type I (n=2), III (n=2), IV (n=4)). ASA grade III in 12/15. Maximum diameter of aneurysm 64 mm (56-74 mm). Aneurysms were excluded using covered stents or branches from the main body to patent visceral vessels (40 target vessels total). Pre-operative and follow-up CT scans (1, 3, and 12 months) were analysed by a single Vascular Interventional Radiologist. RESULTS Technical success for cannulation and stenting of target vessels was 98%. In-hospital mortality was 0%. One patient underwent conversion to open repair. Five had major complications including one paraplegia (type III TAAA) with subsequent recovery. Median length of stay was 9 days (IQR 7-18.75). At a median follow-up of 12 months (9-14), CT confirmed 36/37 (97%) target vessels remain patent. Sac size increased >5 mm in one patient only. There were no type I endoleaks, three type II endoleaks (one embolised, two under surveillance) and three type III endoleaks (two successfully treated percutaneously, one aneurysm ruptured 18 months after endografting and died). CONCLUSION In selected patients, fenestrated and branched stents appear to be a safe and effective alternative to surgery for juxtarenal and thoracoabdominal aneurysms. The complication and mortality rates are low. The long-term durability of this procedure, however, needs to be proven.

ABCA1 Expression in Carotid Atherosclerotic Plaques

Background and Purpose— The ATP-binding cassette transporter A1 (ABCA1) facilitates cholesterol efflux from cells, a key process in reverse cholesterol transport. Whereas previous investigations focused on mutations causing impaired ABCA1 function, we assessed the role of ABCA1 in human carotid atherosclerotic disease. Methods— We compared the mRNA and protein levels of ABCA1, and one of its key regulators, the liver X receptor α (LXRα), between minimally and grossly atherosclerotic arterial tissue. We established ABCA1 and LXRα gene expression by real-time quantitative polymerase chain reaction in 10 control and 18 atherosclerotic specimens. Presence of ABCA1 protein was assessed by immunoblotting. To determine whether differences observed at a local level were reflected in the systemic circulation, we measured ABCA1 mRNA in leukocytes of 10 patients undergoing carotid endarterectomy and 10 controls without phenotypic atherosclerosis. Results— ABCA1 and LXRα gene expression were significantly elevated in atherosclerotic plaques (P<0.0001 and 0.03, respectively). The increased mRNA levels of ABCA1 and LXRα were correlated in atherosclerotic tissue (r=0.85; P<0.0001). ABCA1 protein expression was significantly reduced in plaques compared with control tissues (P<0.0001). There were no differences in leukocyte ABCA1 mRNA expression (P=0.67). Conclusions— ABCA1 gene and protein are expressed in minimally atherosclerotic human arteries. Despite significant upregulation of ABCA1 mRNA, possibly mediated via LXRα, ABCA1 protein is markedly reduced in advanced carotid atherosclerotic lesions. No differences in leukocyte ABCA1 expression were found, suggesting the plaque microenvironment may contribute to the differential ABCA1 expression. We propose that the decreased level of ABCA1 protein is a key factor in the development of atherosclerotic lesions.

Analysis of Flow Patterns in a Patient-Specific Aortic Dissection Model

Aortic dissection is the most common acute catastrophic event affecting the thoracic aorta. The majority of patients presenting with an uncomplicated type B dissection are treated medically, but 25% of these patients develop subsequent aneurysmal dilatation of the thoracic aorta. This study aimed at gaining more detailed knowledge of the flow phenomena associated with this condition. Morphological features and flow patterns in a dissected aortic segment of a presurgery type B dissection patient were analyzed based on computed tomography images acquired from the patient. Computational simulations of blood flow in the patient-specific model were performed by employing a correlation-based transitional version of Menters hybrid k-epsilon/k-omega shear stress transport turbulence model implemented in ANSYS CFX 11. Our results show that the dissected aorta is dominated by locally highly disturbed, and possibly turbulent, flow with strong recirculation. A significant proportion (about 80%) of the aortic flow enters the false lumen, which may further increase the dilatation of the aorta. High values of wall shear stress have been found around the tear on the true lumen wall, perhaps increasing the likelihood of expanding the tear. Turbulence intensity in the tear region reaches a maximum of 70% at midsystolic deceleration phase. Incorporating the non-Newtonian behavior of blood into the same transitional flow model has yielded a slightly lower peak wall shear stress and higher maximum turbulence intensity without causing discernible changes to the distribution patterns. Comparisons between the laminar and turbulent flow simulations show a qualitatively similar distribution of wall shear stress but a significantly higher magnitude with the transitional turbulence model.

ABCA1 and atherosclerosis

ATP binding cassette transporter A1 (ABCA1) mediates the cellular efflux of phospholipids and cholesterol to lipid-poor apolipoprotein A1 (apoA1) and plays a significant role in high density lipoprotein (HDL) metabolism. ABCA1’s role in the causation of Tangier disease, characterized by absent HDL and premature atherosclerosis, has implicated this transporter and its regulators liver-X-receptorγ (LXRγ) and peroxisome proliferator activated receptorγ (PPARγ) as new candidates potentially influencing the progression of atherosclerosis. In addition to lipid regulation, these genes are involved in apoptosis and inflammation, processes thought to be central to atherosclerotic plaque progression. A Medline-based review of the literature was carried out. Tangier disease and human heterozygotes with ABCA1 mutations provide good evidence that ABCA1 is a major candidate influencing atherosclerosis. Animal and in vitro experiments suggest that ABCA1 not only mediates cholesterol and phospholipid efflux, but is also involved in the regulation of apoptosis and inflammation. The complex and beneficial interactions between apoA1 and ABCA1 seem to be pivotal for cholesterol efflux. The expression of the ABCA1 is tightly regulated. Furthermore the plaque microenvironment could potentially promote ABCA1 protein degradation thus compromising cholesterol efflux. PPAR-LXR-ABCA1 interactions are integral to cholesterol homeostasis and these nuclear receptors have proven anti-inflammatory and anti-matrix metalloproteinase activity. Therapeutic manipulation of the ABCA1 transporter is feasible using PPAR and LXR agonists. PPAR agonists like glitazones and ABCA1 protein stabilization could potentially modify the clinical progression of atherosclerotic lesions.

Contemporary management of splanchnic and renal artery aneurysms: results of endovascular compared with open surgery from two European vascular centers.

INTRODUCTION Splanchnic and renal artery aneurysms (SRAAs) are uncommon but potentially life-threatening in case of rupture. Whether these aneurysms are best treated by open repair or endovascular intervention is unknown. The aim of this retrospective study is to report the results of open and endovascular repairs in two European institutions over a fifteen-year period. We have reviewed the available literature published over the 10 last years. METHODS All patients with SRAAs diagnosed from 1995 to 2010 in St Marys Hospital (London, UK) and Henri Mondor Hospital (Créteil, France) were reviewed. Preoperative clinical and anatomical data, operative management and outcomes were recorded from the charts and analyzed. RESULTS 40 patients with 51 SRAAs were identified. There were 21 males and 19 females with a mean age of 57 ± 14.9 years. The aneurysms locations were: 14 (27%) renal, 11 (22%) splenic, 7 (14%) celiac trunk, 7 (14%) superior mesenteric artery, 4 (8%) hepatic, 4 (8%) pancreaticoduodenal arcades, 3 (6%) left gastric and 1 (2%) gastroduodenal. 4 patients presented with a ruptured SRAA. 17 SRAAs in 16 patients were treated by open repair, 15 in 15 patients were treated endoluminally and 17 (mean diameter: 18 mm, range: 8-75 mm) were managed conservatively. One patient with metastatic pulmonary cancer with two mycotic aneurysms of the superior mesenteric artery (75 mm) and celiac trunk (15 mm) was palliated. After endovascular treatment, the immediate technical success rate was 100%. There was no significant difference between open repair and endovascular patients in terms of 30-day post-operative mortality rate and peri-operative complications. No in-hospital death occurred in patients treated electively. Postoperatively, four patients (1 ruptured and 3 elective) suffered non-lethal mild to severe complication in the open repair group, as compared with one in the endovascular group (p = .34). The mean length of stay was significantly higher after open repair as compared with endovascular repair (17 days, range: 8-56 days vs. 4 days, range: 2-6; p < .001). The mean follow-up time was 17.8 months (range: 0-143 months) after open repair, 15.8 months (range: 0-121 months) after endovascular treatment, and 24.8 (range: 3-64 months) for patient being managed conservatively. No late death related to the VAA occurred. In each group, 2 successful reoperations were deemed necessary. In the endovascular group, two patients presented a reperfusion of the aneurysmal sac at 6 and 24 months respectively. CONCLUSION No significant difference in term of 30-day mortality and post-operative complication rates could be identified between open repair and endovascular treatment in the present series. Endovascular treatment is a safe alternative to open repair but patients are exposed to the risk of aneurysmal reperfusion. This mandates careful long-term imaging follow up in patients treated endoluminally.

The Incidence of Spinal Cord Ischaemia Following Thoracic and Thoracoabdominal Aortic Endovascular Intervention

OBJECTIVES To determine the incidence and risk factors for spinal cord ischaemia (SCI) following thoracic and thoracoabdominal aortic intervention. METHODS A prospective database of all thoracic and thoracoabdominal aortic interventions between 2001 and 2009 was used to investigate the incidence of SCI. All elective and emergency cases for all indications were included. Logistic regression was used to investigate which factors were associated with SCI. RESULTS 235 patients underwent thoracic aortic stent grafting; 111(47%) thoracic aortic stent-grafts alone, with an additional 14(6%) branched or fenestrated thoracic grafts, 30(13%) arch hybrid procedures and 80(34%) visceral hybrid surgical and endovascular procedures. The global incidence of SCI for all procedures was 23/235 (9.8%) and this included emergency indications (ruptured TAAA and acute complex dissections) but the incidence varied considerably between types of procedures. Of the 23 cases, death occurred in 4 patients but recovery of function was seen in 6. Thus, permanent paraplegia occurred in 13/235 (5.5%) patients. Of the nine pre-specified factors investigated for association with SCI, only percentage of aortic coverage was significantly associated with the incidence of SCI; adjusted odds ratio per 10% increase in aorta covered=1.78[95% CI 1.18-2.71], p=0.007. The procedures in patients who developed SCI took longer (463.5 versus 307.2 minutes) and utilised more stents (4 versus 2). CONCLUSION SCI following thoracic and thoracoabdominal aortic endovascular intervention is associated with the proportion of aorta covered. The degree of risk varies between different types of procedure and this should be carefully considered in both selection and consenting of patients.

Optimizing the outcome of vascular intervention for Takayasu arteritis

Takayasu arteritis (TA) predisposes to the development of arterial stenoses and aneurysms, and is associated with considerable morbidity and mortality amongst young patients. The aims of this study were to analyse indications and outcomes of surgical intervention, and to assess the potential benefits of immunosuppression and the use of perioperative imaging.

Conservative management of diabetic forefoot ulceration complicated by underlying osteomyelitis: the benefits of magnetic resonance imaging.

Aims  To assess efficacy of conservative management of neuropathic forefoot ulcers with underlying osteomyelitis in subjects with diabetes when magnetic resonance imaging (MRI) is used to confirm or establish diagnosis and to guide antibiotic duration.

Chlamydia pneumoniae Does Not Influence Atherosclerotic Plaque Behavior in Patients With Established Carotid Artery Stenosis

Background and Purpose Research for infectious agents in the etiology of atherosclerosis has identified Chlamydia pneumoniae as a possible candidate. While there is evidence of an association between presence of this microorganism and atherosclerosis, it is unclear whether infection has a genuinely etiologic role in this disease, whether its presence influences clinical outcomes, and, if so, at which stages of disease this occurs. We have approached this issue in patients with advanced carotid artery atherosclerosis using molecular biological detection methods and clinically relevant indicators of pathology in carotid artery atheroma to determine whether the presence of C pneumoniae correlates with plaque instability. Methods C pneumoniae was detected with the use of a sensitive nested polymerase chain reaction. Preoperative embolization and preoperative infarcts were recorded with the use of transcranial Doppler insonation of the middle cerebral artery and cerebral CT, respectively. Results C pneumoniae DNA was detected in 25.5% of a cohort of 98 symptomatic patients. There was no significant difference in plaque stability as measured by embolization rates between the chlamydial-positive and -negative specimens. There was also no correlation between the number of ipsilateral hemispheric infarcts in the territory of the middle cerebral artery and chlamydial status. Conclusions This study confirms that C pneumoniae is a common finding in atherosclerotic plaques of the carotid artery but suggests that the presence of the infectious organism has little detectable impact on plaque instability when measured by clinically significant markers. This raises important questions for the rationale of antibiotic therapy in atherosclerosis.

Update: Complications and management of infrarenal EVAR

Endovascular aortic aneurysm repair (EVAR) is now an established technique for treating many patients with infrarenal abdominal aortic aneurysm. Familiarity with the complications associated with this technique and understanding treatment options are crucial for the lifelong performance of stent graft. This pictorial review article describes the currant role of different imaging modalities in surveillance and discusses the complications and its management strategies.