Martin Claridge

Routine Preoperative Vascular Ultrasound Improves Patency and Use of Arteriovenous Fistulas for Hemodialysis: A Randomized Trial

BACKGROUND AND OBJECTIVES Arteriovenous fistulas (AVFs) are the preferred vascular access for hemodialysis but have a considerable failure rate. This study investigated whether routine preoperative vascular ultrasound results in better AVF outcome than physical examination. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Patients with end-stage kidney disease referred for permanent access formation were assessed by independent examiners using physical examination and ultrasound. After random allocation, the ultrasound report was disclosed to the surgeon for patients in the ultrasound group but not for the clinical group. End points were AVF failure and survival rates, analyzed by intention to treat and by use for hemodialysis. RESULTS AVFs were made in 208 of 218 randomized patients. Clinical and ultrasound groups were similar in terms of patient characteristics, allocation to individual surgeons, and proportion of forearm AVFs. The ultrasound group had a significantly lower rate of immediate failure (4% versus 11%, P = 0.028) and, among failed AVFs, less thrombosis (38% versus 67%, P = 0.029). Primary AVF survival at 1 year was not statistically different (ultrasound = 65%, clinical = 56%, P = 0.081). Assisted primary AVF survival at 1 year was significantly better for the ultrasound group (80% versus 65%, P = 0.012). The number of patients requiring preoperative ultrasound to prevent one AVF failure was 12. CONCLUSIONS Routine preoperative vascular ultrasound in addition to clinical assessment improves AVF outcomes in terms of patency and use for dialysis. National Research Register, United Kingdom, trial number N0046131432.

LDL Cholesterol is Associated with Small Abdominal Aortic Aneurysms

OBJECTIVE To examine the relationship between serum lipids and abdominal aortic aneurysms (AAA). METHODS Two hundred and six males (>50 years) with AAA (> or =30 mm) detected in a population based screening programme were compared with 252 age-matched male controls in a nested case-control study. Smoking status, previous medical and family histories, height, weight, blood pressure, ankle brachial pressure index (ABPI) and non-fasting lipid profile were recorded. RESULTS Cases were found to have significantly higher LDL cholesterol than controls. LDL cholesterol was an independent predictor of the risk for aneurysms in a logistic regression model adjusting for smoking status, family history of AAA, history of ischaemic heart disease, presence of peripheral vascular disease, use of lipid lowering medication and treatment for hypertension. There was a linear effect with increased levels of LDL cholesterol increasing the risk of having a small aneurysm (test for trend p=0.03). CONCLUSION The highly significant association between LDL cholesterol and small aneurysms suggests that LDL, possibly acting via inflammatory mediated matrix degeneration, could be an initiating factor in the development of AAA. The ability of statin therapy to prevent AAA formation requires further investigation.

Measurement of arterial stiffness in subjects with vascular disease: Are vessel wall changes more sensitive than increase in intima–media thickness?

BACKGROUND AND AIMS It is widely accepted that subjects with vascular disease have increased arterial stiffness and intima-media thickness (IMT) when compared with healthy controls. The aim of this study was to investigate indices of arterial stiffness and IMT in the common carotid arteries (CCAs) of subjects with and without peripheral arterial disease (PAD), in order to look for evidence of change in wall quality and quantity to explain increased stiffness that has been found in the arteries of subjects with vascular disease. METHODS AND RESULTS The arterial distension waveform (ADW), IMT, diameter and brachial blood pressure were measured to calculate Youngs Modulus (E) and elastic modulus (Ep) in the common carotid arteries of subjects with and without PAD. 38 subjects with confirmed PAD were compared with 43 normal controls matched for age, sex, smoking and hypertension. The mean diameter (8.35mm [95% CI 7.93-8.77] vs. 6.93mm [6.65-7.20] P<0.001, increase 20%), IMT (0.99mm [0.92-1.07] vs. 0.88mm [0.82-0.93] P=0.020, increase 12.5%), Ep (315kPa [185-444] vs. 190kPa [164-216] P=0.034, increase 66%) and E (1383kPa [836-1930] vs. 744kPa [641-846] P=0.006, increase 86%) were all significantly higher in subjects with PAD. CONCLUSIONS This study suggests that increased stiffness observed in subjects with peripheral vascular disease is a result of change in both quantity and quality of the arterial wall. Changes in indices of arterial stiffness were much higher than changes in IMT and diameter. These preliminary observations may be an indication that indices of arterial stiffness are a sensitive early marker of atherosclerosis.

Current results of endovascular repair of thoraco-abdominal aneurysms

OBJECTIVES Fenestrated and branch endografts represent a totally endovascular solution for high-risk patients with atherosclerotic thoraco-abdominal aortic aneurysms (TAAAs). This study reports the early outcome of endovascular TAAA repair. METHODS Interrogation of a prospective database of consecutive patients who underwent endovascular repair (EVAR) for TAAA between June 2007 and October 2012. RESULTS Sixty-two high-risk patients (55 men; median age 72, range 54-84 years) underwent fenestrated (n = 39) or branch (n = 23) EVAR for non-ruptured TAAA [extent I-III (n = 26) and IV (n = 36)]. Twenty patients had undergone 22 previous aortic procedures. A total of 221 target vessels (coeliac 50, superior mesenteric 61, renal 106, left subclavian 1 and hypogastric 3) were preserved with scallops (n = 17), fenestrations (n = 140) or branches (n = 62) and 201 of these vessels were stent-grafted (coeliac 34, superior mesenteric 58, renal 105, left subclavian 1 and hypogastric 3). The 30-day mortality was 1.6% (n = 1) and one further patient died on postoperative day 62 from respiratory complications. Spinal cord injury (SCI) developed in 5 (8%) patients (3 women and 2 men). Two patients required temporary renal replacement therapy and a further two commenced planned postoperative dialysis. CONCLUSIONS In high-risk patients with TAAA, fenestrated and branch EVAR is associated with low early mortality and requirement for renal support, but the risk of SCI is not insignificant despite the use of cerebrospinal fluid drainage and blood pressure manipulation. Our current practice is to stage the repair of extent I-III aneurysms and this has significantly reduced the incidence of SCI.

Effect of ramipril on renal function in patients with intermittent claudication

Background The Heart Outcomes Prevention Study (HOPE) demonstrated that ramipril resulted in a blood-pressure-independent 25% reduction in cardiovascular events in patients with peripheral arterial disease (PAD). Despite this, general practitioners and vascular surgeons remain reluctant to prescribe ACE inhibitors in this group of patients because of concerns about renal artery stenosis (RAS). We aimed to define the effect of ramipril on renal function in patients with intermittent claudication (IC). Methods and Results Of 132 unselected patients with IC entering the study 78 (59%) were excluded due to: current ACE inhibitor use (38%), renal impairment (serum creatinine above normal range) (15%), known severe RAS (1%) or unwillingness to participate (5%). The remaining 54 patients were titrated to 10 mg ramipril and renal function was monitored at 1, 5, and 12 weeks. Treatment was discontinued during titration in 5 patients due to symptoms (3) or lack of compliance (2). In the remainder, median [IQR] serum creatinine increased (94 [85.8–103.3] to 98 [88.0–106.5] μmol/L, p ≤ 0.001) and median [IQR] GFR decreased (71.5 [64.6–82.3] to 68.7 [59.8–74.7] mL/min per 1.73 m2, p ≤ 0.001) between baseline and 5 weeks. These changes were not considered clinically significant. By 12 weeks these values had returned almost to baseline (Cr 95.5 [88.0–103.25] μmol/L, GFR 71.8 [65.3–77.4] mL/min). No patient had a serum creatinine rise >30%. Conclusion Most of patients with IC and a normal serum creatinine can be safely commenced on ramipril provided they are screened, titrated and monitored as described above. Studies in patients with borderline renal impairment (serum creatinine up to 30% above baseline) are on-going.