M. Hamady

Hybrid Treatment of Complex Aortic Arch Disease with Supra-aortic Debranching and Endovascular Stent Graft Repair

BACKGROUND Aortic arch disease has conventionally been the domain of open surgical repair. Hybrid open and endovascular repair has evolved as an alternative, less invasive, treatment option with promising results. A systematic literature review and analysis of the reported outcomes was undertaken. METHODS An Internet-based literature search using MEDLINE was performed to identify all studies reporting on hybrid aortic arch repair with supra-aortic branch revascularisation and subsequent stent graft deployment. Debranching should involve at least one carotid artery, so that patients merely requiring a carotid-subclavian bypass were not included. Only reports of five patients or more were included in the analysis. Outcome measures were technical success, perioperative, 30-day and late morbidity and mortality. RESULTS Eighteen studies fulfilled our search criteria, and data from 195 patients were entered for the analysis. No comparative studies of hybrid aortic arch repair with other conventional or innovative treatment modalities were identified. Complete arch repair was performed in 122 patients (63%). The overall technical success rate was 86% (167/195). The most common reason for technical failure was endoleak (9%, 17/195). Overall perioperative morbidity and mortality rates were 21% (41/195) and 9% (18/195), respectively. The most common perioperative complication was stroke (7%, 14/195). Four aneurysm-related deaths were reported during follow-up (2%). No long-term data on hybrid aortic arch repair were identified. CONCLUSIONS Hybrid repair of complex aortic arch disease is an alternative treatment option with acceptable short-term results. Stroke remains a frequent complication and mortality rates are significant. Further research with large comparative studies and longer follow-up is required.

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.

Intra-Arterial Immunoselected CD34+ Stem Cells for Acute Ischemic Stroke

Treatment with CD34+ hematopoietic stem/progenitor cells has been shown to improve functional recovery in nonhuman models of ischemic stroke via promotion of angiogenesis and neurogenesis. We aimed to determine the safety and feasibility of treatment with CD34+ cells delivered intra‐arterially in patients with acute ischemic stroke. This was the first study in human subjects. We performed a prospective, nonrandomized, open‐label, phase I study of autologous, immunoselected CD34+ stem/progenitor cell therapy in patients presenting within 7 days of onset with severe anterior circulation ischemic stroke (National Institutes of Health Stroke Scale [NIHSS] score ≥8). CD34+ cells were collected from the bone marrow of the subjects before being delivered by catheter angiography into the ipsilesional middle cerebral artery. Eighty‐two patients with severe anterior circulation ischemic stroke were screened, of whom five proceeded to treatment. The common reasons for exclusion were age >80 years (n = 19); medical instability (n = 17), and significant carotid stenosis (n = 13). The procedure was well tolerated in all patients, and no significant treatment‐related adverse effects occurred. All patients showed improvements in clinical functional scores (Modified Rankin Score and NIHSS score) and reductions in lesion volume during a 6‐month follow‐up period. Autologous CD34+ selected stem/progenitor cell therapy delivered intra‐arterially into the infarct territory can be achieved safely in patients with acute ischemic stroke. Future studies that address eligibility criteria, dosage, delivery site, and timing and that use surrogate imaging markers of outcome are desirable before larger scale clinical trials.

Hybrid Repair of the Aortic Arch in Patients with Extensive Aortic Disease

OBJECTIVE To evaluate the outcome of hybrid treatment of the aortic arch with supra-aortic debranching and endovascular stent-graft repair in a selected group of patients with complex disease. DESIGN Case series study with retrospective analysis of prospectively collected non-randomised data. METHODS Patients with hybrid repair of complex arch disease at a single centre over a 6-year period were enrolled in the study. Only patients with extensive arch pathologies requiring debranching of at least the left carotid artery were considered. Patients were divided into those who underwent complete and partial supra-aortic revascularisation. The χ2 test was used to evaluate differences in outcomes. Logistic regression analyses were applied to identify predictors of poor outcome. RESULTS A total of 33 patients were included in the study. Complete and partial arch repair was performed in nine and 24 patients, respectively. The aortic disease extended to the thoracic and abdominal aorta in 39% and 52% of the patients, respectively. One-third of the patients (30%) were treated on an urgent/emergency basis. Elective 30-day mortality and morbidity rates were 13% and 35%, respectively. Early mortality was significantly higher in the complete arch repair group (p=0.046). Pre-existing renal impairment was identified as a poor prognostic factor. All extra-anatomic bypasses remained patent and no aortic disease-related deaths occurred during a mean follow-up period of 23 months (range, 1.5-58 months). Complete arch repair was associated with an increased incidence of late endoleak (p=0.018). CONCLUSIONS Hybrid treatment of the aortic arch provides a feasible alternative treatment in patients who are high risk for conventional open surgical repair. Careful selection of patients is required to achieve satisfactory results.

Initial findings and potential applicability of computational simulation of the aorta in acute type B dissection

OBJECTIVE Type B aortic dissection can be acutely complicated by rapid expansion, rupture, and malperfusion syndromes. Short-term adverse outcomes are associated with failure of the false lumen to thrombose. The reasons behind false lumen patency are poorly understood, and the objective of this pilot study was to use computational fluid dynamics reconstructions of aortic dissection cases to analyze the effect of aortic and primary tear morphology on flow characteristics and clinical outcomes in patients with acute type B dissections. METHODS Three-dimensional patient-specific aortic dissection geometry was reconstructed from computed tomography scans of four patients presenting with acute type B aortic dissection and a further patient with sequential follow-up scans. The cases were selected based on their clinical presentation. Two were complicated by acute malperfusion that required emergency intervention. Three patients were uncomplicated and were managed conservatively. The patient-specific aortic models were used in computational simulations to assess the effect of aortic tear morphology on various parameters including flow, velocity, shear stress, and turbulence. RESULTS Pulsatile flow simulation results showed that flow rate into the false lumen was dependent on both the size and position of the primary tear. Linear regression analysis demonstrated a significant relationship between percentage flow entering the false lumen and the size of the primary entry tear and an inverse relationship between false lumen flow and the site of the entry tear. Subjects complicated by malperfusion had larger-dimension entry tears than the uncomplicated cases (93% and 82% compared with 32% and 55%, respectively). Blood flow, wall shear stress, and turbulence levels varied significantly between subjects depending on aortic geometry. Highest wall shear stress (>7 Pa) was located at the tear edge, and progression of false lumen thrombosis was associated with prolonged particle residence times. CONCLUSIONS Results obtained from this preliminary work suggest that aortic morphology and primary entry tear size and position exert significant effects on flow and other hemodynamic parameters in the dissected aorta in this preliminary work. Blood flow into the false lumen increases with increasing tear size and proximal location. Morphologic analysis coupled with computational fluid dynamic modeling may be useful in predicting acute type B dissection behavior allowing for selection of proper treatment modalities, and further confirmatory studies are warranted.

The suitability of thoraco-abdominal aortic aneurysms for branched or fenestrated stent grafts--and the development of a new scoring method to aid case assessment.

OBJECTIVE To determine the proportion of TAAAs which might be suitable for pure endovascular repair based on aneurysm morphology and to develop an MDCTA based scoring system to grade case complexity. DESIGN 70 consecutive MDCTA of patients with TAAAs were analysed in relation to specific morphological characteristics. METHODS The characteristics included potential stent landing zone lengths, arch angulation, thoraco-abdominal aorta angulation, branch vessel origin stenosis, access tortuosity/diameter and aortic dissection. RESULTS 60% of TAAAs would be suitable for branched/fenestrated stent grafting but 40% are unsuitable due to adverse anatomy. 27% had an aortic arch angulation of ≤ 110° and 24% had descending thoracic aorta angulation of ≤ 90°. Significant ostial stenosis was identified in 31% of celiac arteries, 7% superior mesenteric arteries, 24% left renal artery and 19% right renal arteries. 11% of left common iliac and 7% right common iliac arteries had angulation of ≤ 70°. There were 26 cases with aortic dissection and 54% of these had a true lumen of ≤ 26 mm. CONCLUSION Successful fenestrated/branched stent graft repair of TAAAs requires adequate landing zones, cannulation of visceral arteries and suitable diameter access vessels. 60% of TAAAs studied were suitable for branched/fenestrated stent graft repair but 40% of TAAAs were unsuitable; aortic angulation, visceral vessel ostial stenosis and dissection true lumen diameter were the principle issues. Development in stent technology may address these anatomical challenges.

Patient-specific analysis of displacement forces acting on fenestrated stent grafts for endovascular aneurysm repair

Treatment options for abdominal aortic aneurysm (AAA) include highly invasive open surgical repair or minimally invasive endovascular aneurysm repair (EVAR). Despite being minimally invasive, some patients are not suitable for EVAR due to hostile AAA morphology. Fenestrated-EVAR (F-EVAR) was introduced to address these limitations of standard EVAR, where AAA is treated using a Fenestrated Stent Graft (FSG). In order to assess durability of F-EVAR, displacement forces acting on FSGs were analysed in this study, based on patient-specific geometries reconstructed from computed tomography (CT) scans. The magnitude and direction of the resultant displacement forces acting on the FSG were numerically computed using computational fluid dynamics (CFD) with a rigid wall assumption. Although displacement force arises from blood pressure and friction due to blood flow, numerical simulations elucidated that net blood pressure is the dominant contributor to the overall displacement force; as a result, time dependence of the resultant displacement force followed pressure waveform very closely. The magnitude of peak displacement force varied from 1.9N to 14.3N with a median of 7.0N. A strong positive correlation was found between inlet cross-sectional area (CSA), anterior/posterior (A/P) angle and the peak displacement force i.e. as inlet CSA or A/P angle increases, the magnitude of resultant displacement increases. This study manifests that while loads exerted by the pulsatile flow dictates the cyclic variation of the displacement force, its magnitude depends not only on blood pressure but also the FSG morphology, with the latter determining the direction of the displacement force.

Design and Validation of an Error Capture Tool for Quality Evaluation in the Vascular and Endovascular Surgical Theatre

BACKGROUND The unique and complex vascular and endovascular theatre environment is associated with significant risks of patient harm and procedural inefficiency. Accurate evaluation is crucial to improve quality. This pilot study attempted to design a valid, reproducible tool for observers and teams to identify and categorise errors. METHODS Relevant published literature and previously collected ethnographic field notes from over 250 h of arterial surgery were analysed. A comprehensive log of vascular procedural errors was compiled and twelve vascular experts graded each error for the potential to disrupt procedural flow and cause harm. Using this multimodal approach, the Imperial College Error CAPture (ICECAP) tool was developed. The tool was validated during 21 consecutive arterial cases (52 h operating-time) as an observer-led error capture record and as a prompt for surgical teams to determine the feasibility of error self-reporting. RESULTS Six primary categories (communication, equipment, procedure independent pressures, technical, safety awareness and patient related) and 20 error sub-categories were determined as the most frequent and important vascular procedural errors. Using the ICECAP, the number of errors detected correlated well between two observers (Spearman rho = 0.984, p < 0.001). Both observers identified all moderate or severe errors similarly and categorised all but 4/139 (2.9%) of the total errors in an identical fashion. Self-reporting of errors without prompting identified a mean of 24.4% (range 0-50%) of all recorded errors, whereas surgical teams reported a mean of 69.7% (range 50-100%) of errors when ICECAP error-category prompts were used. CONCLUSION The ICECAP tool may be useful for capturing and categorising errors that occur during vascular/endovascular procedures. ICECAP may also have a role as an error recall prompt for self-reporting purposes by vascular surgical teams.