Ian M. Nordon

Pathophysiology and epidemiology of abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are found in up to 8% of men aged >65 years, yet usually remain asymptomatic until they rupture. Rupture of an AAA and its associated catastrophic physiological insult carries overall mortality in excess of 80%, and 2% of all deaths are AAA-related. Pathologically, AAAs are associated with inflammation, smooth muscle cell apoptosis, and matrix degradation. Once thought to be a consequence of advanced atherosclerosis, accruing evidence indicates that AAAs are a focal representation of a systemic disease of the vasculature. Risk factors for AAAs include increasing age, male sex, smoking, and low HDL-cholesterol levels. Familial associations exist and although susceptibility genes have been described on the basis of candidate-gene studies, robust genetic studies have failed to discover causative gene mutations. The surgical management of AAAs has been revolutionized by minimally invasive endovascular repair. Ongoing randomized trials will establish whether endovascular repair confers a survival advantage over open surgery for patients with a ruptured AAA. In many countries, centralization of vascular surgical services has largely been driven by the improved outcomes of elective aneurysm surgery in specialized centers, the widespread adoption of endovascular techniques, and the introduction of screening programs.

Modern Treatment of Juxtarenal Abdominal Aortic Aneurysms with Fenestrated Endografting and Open Repair ― A Systematic Review

INTRODUCTION Advances in endovascular technology have led to the introduction of fenestrated stents to treat juxtarenal aneurysms (JRAs), previously deemed unsuitable for standard endovascular repair (EVR). This article reviews the outcomes of fenestrated technology and makes a comparison with open repair. METHODS A systematic review of the literature was performed. RESULTS No randomised studies were identified. 8 cohort studies reporting 368 f-EVR cases and 12 cohorts reporting 1164 open repairs of JRAs were identified. Analysis of outcome measures found the f-EVR and open cohorts to be homogeneous. Combining studies identified an increased 30-day mortality after open repair when compared to f-EVR (Relative risk (RR) 1.03, 95% Confidence interval (CI) 1.01-1.04, p=.02), 2% increased absolute mortality. No difference was identified in postoperative permanent dialysis dependence (RR 1.00, CI 0.99-1.01, p=1). Transient renal failure was more common following open repair (RR 1.06, CI 1.01-1.12, p=.03). Early re-interventions were less common following open repair (RR 0.87, CI 0.83-0.91, p=.0001). CONCLUSIONS Selective f-EVR appears to have reduced peri-operative mortality compared with traditional open surgery, yet selectivity within the study groups and lack of a rigorous classification prohibit more robust comparison. Promising short-term results confirm a role for f-EVR in management of complex abdominal aneurysms.

A prospective double-blind randomized controlled trial of radiofrequency versus laser treatment of the great saphenous vein in patients with varicose veins.

Background:Endovenous ablation of varicose veins using radiofrequency ablation (RFA) and endovenous laser therapy (EVLT) has reported advantages over traditional open surgical treatment. There is little evidence comparing the efficacy and patient-reported outcomes between the 2 endovenous solutions. This study compares the RFA and EVLT strategies in a prospective double-blind clinical trial. Methods:Consecutive patients with primary unilateral great saphenous vein (GSV) reflux undergoing endovenous treatment were randomized to RFA (VNUS ClosureFAST) or EVLT (810-nm diode laser). The primary outcome measure was GSV occlusion at 3 months after treatment. Secondary outcome measures were occlusion at 7 days, postoperative pain, analgesic requirement, and bruising, assessed at day 7 after surgery. Quality of life (QoL) was assessed preoperatively and 3 months after surgery using the Aberdeen Varicose Vein Questionnaire (AVVQ) and EQ-5D. Results:A total of 159 patients were randomized to RFA (79 patients) or EVLT (80 patients). Groups were well matched for demographics, disease extent, severity, and preoperative QoL. Duplex scanning confirmed 100% vein occlusion at 1 week in both groups. At 3 months, occlusion was 97% for RFA and 96% for EVLT; P = 0.67. Median (interquartile range) percentage above-knee bruise area was greater after EVLT 3.85% (6.1) than after RFA 0.6% (2); P = 0.0001. Postoperative pain assessed at each of the first 7 postoperative days was less after RFA (P = 0.001). Changes in the AVVQ (P = 0.12) and EQ-5D (P = 0.66) at 3 months were similar in both groups. Conclusions:RFA and EVLT offer comparable venous occlusion rates at 3 months after treatment of primary GSV varices; with neither modality proving superior. RFA is associated with less periprocedural pain, analgesic requirement, and bruising. Registration number: ISRCTN63135694 (http://www.controlled-trials.com)

Secondary Interventions Following Endovascular Aneurysm Repair (EVAR) and the Enduring Value of Graft Surveillance

OBJECTIVE Lifelong imaging surveillance is currently recommended for all patients following endovascular aortic aneurysm repair (EVR). The modality, timing and overall necessity of surveillance has recently been brought into question. This review reports contemporary secondary intervention rates and explores surveillance imaging pick-up rates and reports the evidence supporting modified EVR surveillance programs. DESIGN Systematic review of literature (2002-2009) and meta-analysis of Kaplan-Meier re-intervention-free survival estimates. RESULTS 32 Papers were included in final analysis. 17,987 EVR cases were reported. Crude annual secondary intervention rates from the US population registries were 3.7%/year (range 1.7-4.3%). Combined re-intervention-free survival estimates, from 14 series (10,365 cases), demonstrated a linear progression with 89.9%, 86.9% and 81.5% of grafts without secondary procedures at 2, 3 and 5 years respectively. 3 Reports (1249 cases) differentiated between interventions directed by surveillance or outside surveillance protocols. Surveillance imaging alone initiated the secondary interventions in 1.4-9% of cases; >90% of EVR cases received no benefits from surveillance scans. DISCUSSION Some format of surveillance following EVR probably remains necessary despite a reduction in secondary interventions with modern stent-grafts. Surveillance should be targeted at those stent-grafts and patients at high risk of complications. Further work is justified to identify this group.

Review of Current Theories for Abdominal Aortic Aneurysm Pathogenesis

Atherosclerotic plaques are a feature of abdominal aortic aneurysms (AAAs). Atherosclerosis and AAA appear to share similar risk factors. These observations have led to the conclusion that AAAs are a consequence of advanced atherosclerosis. This review explores current theories regarding the pathogenesis of AAA and their implications for treatment. A systematic literature search was conducted using the search terms abdominal aortic aneurysm, atherosclerosis, pathogenesis, and systemic disease. Articles were categorized according to the association of AAAs with atherosclerosis, arteriomegaly, peripheral aneurysm, systemic expression, genetics, autoimmunity, oxidative stress, and systemic disease. Twenty-nine articles reporting changes in the systemic vasculature associated with AAA and 12 articles examining the shared risk factor hypothesis were identified. There is insufficient evidence to confirm that AAAs are the result of advanced atherosclerosis. The bulk of evidence points to AAA disease being a systemic disease of the vasculature, with a predetermined genetic susceptibility leading to a phenotype governed by environmental factors.

Endovascular management of chronic aortic dissection in patients with Marfan syndrome

INTRODUCTION Marfan syndrome patients are prone to aortic dilatation, dissection, and rupture. Success of aortic root replacement has generated a cohort of patients surviving longer and presenting with distal aortic dissection and enlargement. Thoracic endovascular stent-graft repair (TEVR) is being increasingly utilized to exclude aneurysms resulting from chronic aortic dissection. This report explores the role of TEVR in Marfan patients with this pathology. METHODS Review of a prospectively maintained database identified seven patients with Marfan syndrome offered endovascular repair of aneurysmal chronic aortic dissection. All patients had previous aortic root repair. Talent or Valiant (Medtronic Vascular, Santa Rosa, Calif) aortic stent-grafts were used to occlude the dissection entry tear and cover the thoracic aorta. Electronic data, case notes, and radiological surveillance were analyzed. RESULTS Seven consecutive patients (six male; mean age, 45.9 +/- 10 years, range, 29 to 63) underwent successful thoracic stent-graft deployment. Mean aortic aneurysmal diameter was 63.4mm (+/-11.2) with six of seven dissections extending to the aortic bifurcation. No perioperative neurological events occurred. Thirty-day mortality was 1/7 (14%) due to congestive cardiac failure. At median 16 month follow-up, two of six cases (33%) required intervention for endoleak. Aortic false lumen thrombosis (FLT) occurred in 5/6 (83%) cases and partial FLT occurred in 1/6 (17%). All thoracic aortas continued to dilate during follow-up. Crude median aortic growth rate was 7.2 mm/year (range, 3.5 to 19 mm). CONCLUSION TEVR in Marfan syndrome patients with chronic aortic dissection is technically feasible. However, post intervention surveillance confirms that the aorta continues to dilate despite graft deployment and false lumen thrombosis. Endovascular repair may offer a viable option in patients who have contraindications to open surgery, but longer follow up of more patients is required to define the place of this therapy.

Surgical management of varicose veins: meta-analysis.

Open surgery remains the gold standard by which endovascular treatment of superficial chronic venous insufficiency is measured. This meta-analysis of randomized controlled trials reviews the current evidence base, comparing open and endovascular treatment of varicose veins. Systematic review of studies reporting duplex scan follow-up after open surgical, laser (endovenous laser therapy [EVLT]), or radiofrequency (VNUS Closure device, VNUS Medical Technologies, San Jose, CA) treatment of refluxing great saphenous veins was completed. Primary outcome measures were occlusion and complication rates and time taken to resume work. No significant difference in recurrence rates at 3 months between open surgery and EVLT (RR 2.19, 95% CI 0.99–4.85, p = .05) or VNUS device (RR 7.57; 95% CI 0.42–136.02) were found. Return to work is significantly faster following VNUS (by 8.24 days; 95% CI 10.50–5.97) or EVLT (by 5.02 days; 95% CI 6.52–3.52). Endovascular treatment of varicose veins is safe and effective and offers the significant advantage of rapid recovery.

Existing risk prediction methods for elective abdominal aortic aneurysm repair do not predict short-term outcome following endovascular repair

OBJECTIVE Improving the safety of elective abdominal aortic aneurysm (AAA) repair has become an imperative. Five well-described risk-scoring systems developed on open aneurysm repair (OR) were tested on a multicenter contemporary sample of patients undergoing endovascular repair of AAA (EVR) to determine if they predicted 30-day morbidity and mortality. METHODS The Glasgow score (GAS), combined prognostic index (CPI), and its modification (M-CPI), the Leiden score and the Vascular Biochemical and Haematological Outctome Model (VBHOM) score were studied using a retrospective database of 846 patients. Thirty-day mortality and serious morbidity were used as end-points. A receiver-operator characteristic curves was plotted and the area under this (known as the c-statistic) was calculated to determine discriminatory ability of each model. RESULTS Incidence of postoperative mortality was 2.2% and serious morbidity was 12.3%. All scores were predictive of mortality except the Leiden score, which had a c-statistic of 0.603 (95% CI, 0.485-0.720; P = .123). The VBHOM score and the M-CPI had a c-statistic of 0.649 (95% CI, 0.514 -0.783; P = .026) and 0.653 (95% CI, 0.544-0.763; P = .026), respectively. The best performing scores were the GAS and CPI, which had a c-statistic of 0.677 (95% CI, 0.559-0.795; P = .008) and 0.679 (95% CI, 0.572-0.787; P = .007), respectively. No score effectively predicted morbidity. CONCLUSION None of the available scores predicted the outcome of EVR with enough accuracy to be recommended for clinical use. To improve preoperative risk prediction in EVR validation of new systems is required, taking into account morphologic features of the aneurysm to predict medium-term morbidity and re-intervention.

Validation of DynaCT in the Morphological Assessment of Abdominal Aortic Aneurysm for Endovascular Repair

Purpose: To evaluate the feasibility of intraoperative 3-dimensional rotational angiography (DynaCT) as a single tool to assess suitability for endovascular aneurysm repair (EVAR) and for sizing the stent-graft. Methods: Twenty elective patients undergoing EVAR were prospectively recruited. All had preoperative multidetector computed tomography (CT) scans and intraoperative (pre-stent deployment) DynaCT scans. Images were read independently by 4 experienced endovascular practitioners. A total of 17 morphological variables, including aneurysm neck diameter and length, were measured from the CT and DynaCT images and compared. Bland-Altman plots examined intraclass correlation of continuous outcomes; kappa correlation coefficient assessed agreement of ordinal results. Results: The mean DynaCT radiation dose was 3751±835 μGym 2 . The mean difference between DynaCT and multidetector CT in aneurysm neck diameter measurement was − 1.5 mm (95% CI −4.9 to 1.9). Differences in left and right common iliac artery diameters were −1.9 mm (95% CI −6.3 to 2.4) and −2.1 mm (95% CI −6.9 to 2.7), respectively. For presence of neck thrombus, the group kappa statistic was 0.51 (p<0.0001); for neck calcification, the kappa was 0.07 (p = 0.29). Nine (45%) cases had incomplete information on DynaCT because external iliac arteries were not included in the scan. Conclusion: DynaCT provides adequate preoperative imaging for morphological assessment of aortic anatomy. The greatest limitation is the evaluation of access vessels and underestimation of calcification. Due to current limited detector size, precise positioning is essential to attain all necessary sizing information using DynaCT.

Management of acute aortic syndrome and chronic aortic dissection.

Acute aortic syndrome (AAS) describes several life-threatening aortic pathologies. These include intramural hematoma, penetrating aortic ulcer, and acute aortic dissection (AAD). Advances in both imaging and endovascular treatment have led to an increase in diagnosis and improved management of these often catastrophic pathologies. Patients, who were previously consigned to medical management or high-risk open surgical repair, can now be offered minimally invasive solutions with reduced morbidity and mortality. Information from the International Registry of Acute Aortic Dissection (IRAD) database demonstrates how in selected patients with complicated AAD the 30-day mortality from open surgery is 17% and endovascular stenting is 6%. Despite these improvements in perioperative deaths, the risks of stroke and paraplegia remain with endovascular treatment (combined outcome risk 4%). The pathophysiology of each aspect of AAS is described. The best imaging techniques and the evolving role of endovascular techniques in the definitive management of AAS are discussed incorporating strategies to reduce perioperative morbidity.