Association between metformin prescription and growth rates of abdominal aortic aneurysms.

BACKGROUND: It has been suggested that diabetes medications, such as metformin, may have effects that inhibit abdominal aortic aneurysm (AAA) growth. The aim of this study was to examine the association of diabetes treatments with AAA growth in three patient cohorts. METHODS: AAA growth was studied using ultrasound surveillance in cohort 1, repeated CT in cohort 2 and more detailed repeat CT in cohort 3. Growth was estimated by the mean annual increase in maximum AAA diameter. RESULTS: A total of 1697 patients with an AAA were studied, of whom 118, 39 and 16 patients were prescribed metformin for the treatment of diabetes in cohorts 1, 2 and 3 respectively. Prescription of metformin was associated with a reduced likelihood of median or greater AAA growth in all three cohorts (cohort 1: adjusted odds ratio (OR) 0·59, 95 per cent c.i. 0·39 to 0·87, P = 0·008; cohort 2: adjusted OR 0·38, 0·18 to 0·80, P = 0·011; cohort 3: adjusted OR 0·13, 0·03 to 0·61, P = 0·010). No other diabetes treatment was significantly associated with AAA growth in any cohort. CONCLUSION: These findings suggest a potential role for metformin in limiting AAA growth.

Detection of Anomalous Cervical Internal Carotid Artery Branches by Colour Duplex Ultrasound.

OBJECTIVES: Conventional anatomical descriptions of the cervical internal carotid artery (ICA) report that no branches arise from this segment. However reports of ICA branches exist. The study aim was to determine the prevalence of anomalous branches of the ICA using colour duplex ultrasound (CDU). METHODS: Four hundred consecutive patients (800 carotid vessels) referred to a tertiary hospital vascular laboratory for investigation of carotid disease were included. A clear differentiation of a low resistive ICA and a high resistive external carotid artery (ECA) waveform was required. CDU was performed on a Philips IU22 ultrasound system with a 9-3 MHz linear array transducer employing a standard carotid imaging protocol. The origin of each ICA branch was identified using B-mode and CDU. Anatomical orientation of ICA branches and distance from bifurcation was recorded and spectral CDU analysis was performed. RESULTS: Twenty ICA branches, tracking cephaladly, were detected in 16 patients (4%), or 2.5% (20/800) vessels. The median age was 73 years; 50% were female and 50% male. All patients demonstrated a single branch [unilateral anomaly (n = 12 patients), bilateral anomaly (n = 4) patients]. Eighty-five percent arose from the posterior wall of the ICA. The median distance from ICA bifurcation was 4 mm (range 0-18 mm). ICA branch diameters ranged from 1.2 mm to 2.4 mm (median 1.4 mm, mean 1.6 mm). Eighty percent of ICA branches had less than 50% stenosis. Spectral analysis revealed high resistive waveforms in all branches. CONCLUSIONS: Branches from the ICA exist and can be characterised with CDU. Prevalence in a tertiary hospital referral cohort is 4%. Given their potential clinical implications, standard carotid imaging protocols should consider routine assessment and reporting of ICA branches.

Outcomes of infected abdominal aortic grafts managed with antimicrobial therapy and graft retention in an unselected cohort.

OBJECTIVE: To document the treatment of all patients with infected aortic grafts at Christchurch Hospital between 1999 and 2010, focussing on the mortality and morbidity of those treated without graft explantation. METHODS: Cases of infected aortic grafts were reviewed. Cases required a compatible clinical syndrome, CT imaging and tissue/blood culture results. RESULTS: Eighteen patients were identified. Organisms isolated at diagnosis from blood or graft site were Staphylococcus aureus 6 (MRSA 1), beta haemolytic streptococci 2, enteric organisms 9.There was no isolate from 2. One case had graft explantation and brief antimicrobial therapy. Seventeen patients had the graft retained. Of these, 14 received intravenous antimicrobial therapy for 6 weeks and 14 lifelong oral therapy. None died during their initial admission or within 30 days. During a mean follow-up of 57 months, 10 (59%) relapsed (median time 31 months, range 0--98), 4 (24%) underwent graft explantation and 10 (59%) died (median 40 months, range 1e 198). Four of 10 who relapsed had organisms isolated (all enteric). CONCLUSION: Patients treated with lifelong antimicrobial therapy and graft retention survived a median of 41 months, with low early mortality although over half relapsed. Empiric therapy should cover skin organisms and enteric organisms, even for those outside the post-operative period.

Spectral CT of carotid atherosclerotic plaque: comparison with histology.

OBJECTIVE: To distinguish components of vulnerable atherosclerotic plaque by imaging their energy response using spectral CT and comparing images with histology. METHODS: After spectroscopic calibration using phantoms of plaque surrogates, excised human carotid atherosclerotic plaques were imaged using MARS CT using a photon-processing detector with a silicon sensor layer and microfocus X-ray tube (50 kVp, 0.5 mA) at 38-µm voxel size. The plaques were imaged, sectioned and re-imaged using four threshold energies: 10, 16, 22 and 28 keV; then sequentially stained with modified Von Kossa, Perl's Prussian blue and Oil-Red O, and photographed. Relative Hounsfield units across the energies were entered into a linear algebraic material decomposition model to identify the unknown plaque components. RESULTS: Lipid, calcium, iron and water-like components of plaque have distinguishable energy responses to X-ray, visible on spectral CT images. CT images of the plaque surface correlated very well with histological photographs. Calcium deposits (>1,000 µm) in plaque are larger than iron deposits (<100 µm), but could not be distinguished from each other within the same voxel using the energy range available. CONCLUSIONS: Spectral CT displays energy information in image form at high spatial resolution, enhancing the intrinsic contrast of lipid, calcium and iron within atheroma. KEY POINTS: Spectral computed tomography offers new insights into tissue characterisation. Components of vulnerable atherosclerotic plaque are spectrally distinct with intrinsic contrast. Spectral CT of excised atherosclerotic plaques can display iron, calcium and lipid. Calcium deposits are larger than iron deposits in atheroma. Spectral CT may help in the non-invasive detection of vulnerable plaques.

Endovascular repair of the thoracic aorta: predictors of 30-day mortality in patients on the New Zealand Thoracic Aortic Stent Database (NZ TAS).

OBJECTIVES: To evaluate data in the New Zealand Thoracic Aortic Stent database to try and identify a scoring system that could predict 30-day mortality in patients undergoing stenting of the descending thoracic aorta (TEVAR). DESIGN: Retrospective analysis of the New Zealand thoracic aortic stent database between December 2001 and August 2007. MATERIALS AND METHODS: The 30-day mortality of the 122 patients is 7.38% (n=9). Risk factors were recorded based on the Society of Thoracic Surgeons (STS) risk score. Glasgow aneurysm score was calculated and the pathology being treated analysed. Univariate analysis was carried out. RESULTS: The mortality of three pathology groups was compared. 30-day mortality was 2.04% (n=1) in the elective aneurysm group, 17.95% (n=7) in the complicated Stanford type B dissection group, and 0% (n=0) in the trauma group. Thirty-day mortality is significantly higher in the dissection group compared with the elective aneurysm (p=0.02) and trauma (p=0.03) groups. The most frequent risk factors in the dissection group of patients were peripheral vascular disease, smoking and hypertension. Although percentage mortality is higher with increasing GAS, the results are not statistically significant (p=0.34). No independent risk factors were identified from the STS risk score data. CONCLUSION: No specific risk score system seems to be able to predict mortality in TEVAR patients.

Outcomes of endovascular repair of acute thoracic aortic injury: interrogation of the New Zealand thoracic aortic stent database (NZ TAS).

OBJECTIVES: Report the New Zealand national experience of endovascular repair of acute traumatic thoracic aortic injuries (TTAIs). DESIGN: Retrospective analysis of the New Zealand thoracic aortic stent database between December 2001 and December 2007. MATERIALS AND METHODS: Of the 134 patients on the database, 27 patients (20%) underwent endovascular repair of TTAI. Data collected included age, sex, cause of injury, details of the procedure, complications and mortality. RESULTS: Most patients were young, median age 20 (15-78), male (n=19, 70%), and involved in motor vehicle accidents (n=23, 85%). Median length of aorta stented was 117 mm (77-200 mm). Great vessel origins were covered intentionally in 23 (85%) patients, four (17%) requiring a hybrid procedure. Average procedure time was 98.3 min (35-180). Primary technical success was 96%, secondary technical success 100%. Endoleaks were observed in four (15%) patients, one requiring a second endovascular procedure. There were no conversions to open surgery. Procedure-related complications occurred in four (15%) patients. No patient developed cord injury. All cause mortality at 30 days is one (4%) and at discharge is two (7%) due to associated poly-trauma. CONCLUSION: Our results add further evidence of the safety of endovascular repair of thoracic aortic injury and compare favourably with those of other centres.

Renal artery stenosis: a common and important problem in patients with peripheral vascular disease.

OBJECTIVE: To study the prevalence, severity, vascular risk factors, and clinical implications of renal artery stenosis in patients with peripheral vascular disease. DESIGN: Cross-sectional study of consecutive patients who were electively referred from the department of vascular surgery for lower limb digital subtraction angiography. SETTING: St. George's Hospital, London, United Kingdom. SUBJECTS: One hundred twenty-seven patients presenting with intermittent claudication or lower limb ischemic ulceration. MAIN OUTCOME MEASURES: Prevalence and clinical importance of renal artery stenosis in patients with peripheral vascular disease adjusted for the confounding effects of age and hypertension. RESULTS: Of the 127 patients, 57 (44.9%) had renal artery disease, of whom 22 (17.3%) had mild disease, 20 (15.7%) had severe disease, and 15 (11.8%) had bilateral renal artery stenosis. There was a significant positive relationship between the presence of renal artery stenosis and the severity of peripheral vascular disease (p = 0.00015). The risk of having renal artery stenosis was nearly four times greater in those with three to four vessels affected and nearly seven times greater in those with five or more vessels affected as compared with those with a milder degree of peripheral vascular disease (one or two vessels affected). This association persisted when the confounding effect of age and hypertension was accounted for. Six patients (31.6%) with renal artery stenosis who underwent revascularization for peripheral vascular disease died during the early postoperative period of cardiac or renal complications. None of the patients with normal renal arteries who had similar surgery developed postoperative complications (p = 0.005). CONCLUSIONS: Renal artery stenosis is a common independent feature in patients with peripheral vascular disease, and its prevalence increases with the increasing severity of the peripheral vascular disease. The postoperative risk following revascularization for peripheral vascular disease appears to be greater in those patients with renal artery stenosis. All patients studied with digital subtraction angiography for peripheral vascular disease should have an aortic flush performed to image the renal arteries. This information may be used to identify those patients likely to develop postoperative complications during peripheral revascularization.

Non-invasive screening for renal artery stenosis with ultrasound contrast enhancement.

OBJECTIVE: Our aim was to evaluate duplex ultrasound imaging in the identification of renal artery stenosis using a new technique to enhance the recorded Doppler signal. DESIGN: Colour Doppler studies of interlobar renal arteries were performed before and after enhancement using an intravenous contrast of galactose microparticle suspension containing microbubbles (Levovist, Schering) in patients with angiographically confirmed renal artery stenosis. SETTING: Blood Pressure Unit, St. George's Hospital Medical School, and Department of Radiology. The Middlesex Hospital, London, UK. PARTICIPANTS: Twenty-one consecutive hypertensive patients in whom the diagnosis of renal artery stenosis was made on digital subtraction angiography. MAIN OUTCOME MEASURES: The diagnosis of haemodynamically significant renal artery stenosis (> or = 60% on angiography). RESULTS: With Levovist, there was a 20 db increase in the Doppler intensity and, as a result, intrarenal signals were much more clearly delineated and distinct spectral waveforms were obtained from all but one kidney, which was occluded. Significant associations were found between the degree of stenosis (as assessed by angiography) and the following Doppler parameters: diastolic velocity (F = 7.6; P < 0.01), acceleration time (F = 33.5, < 0.0001), peak systolic velocity (F = 37.7, P < 0.0001) and acceleration (F = 60.0; P < 0.0001). Without enhancement, there were five false-positive and two false-negative examinations (sensitivity 85%; specificity 79%) using the acceleration cut-off value of 3.5 m/s2 to identify haemodynamically significant renal artery stenosis (> or = 60% on angiography). After contrast enhancement, there were only three false-positive and one false-negative examinations (sensitivity 94% and specificity of 88%) using the acceleration cut-off value of 3.75 m/s2 and the examination time was reduced by approximately half (sensitivity and specificity of 90% using the acceleration cut-off value of 3.5 m/s2). CONCLUSIONS: Our results suggest that renal duplex scanning using contrast enhancement is a promising new non-invasive technique in screening patients with suspected renal artery stenosis. Contrast enhancement produces more reproducible spectral waveforms, improves accuracy and halves the examination time.

Ultrasound of the extracranial vertebral artery.

Ultrasound of the extracranial vertebral artery (VA) is a valuable technique. This review outlines VA anatomy and the technical aspects of ultrasound scanning of the VA, then proceeds to demonstrate and discuss the use of ultrasound of the VA in identifying vertebral-subclavian and coronary-subclavian steal syndromes, aortic valve disease, stenosis or occlusion of the VA itself, dissection and aneurysm of the VA, and vertebrobasilar insufficiency.

Coronary subclavian steal syndrome: non-invasive imaging and percutaneous repair.

Although coronary subclavian steal syndrome (CSSS) is relatively uncommon, it is a well documented cause of graft failure in patients having undergone coronary artery bypass grafting (CABG) using the left internal mammary artery (LIMA). Here we report a case of CSSS induced by restenosis of a left subclavian artery (SCA) origin stent, identified by increased velocities within the stent and an abnormal ipsilateral vertebral artery (VA) waveform on Duplex ultrasound imaging. This was successfully treated percutaneously by re-stenting, resulting in restoration of normal SCA waveforms and velocities, and normalization of the ipsilateral VA waveform.

Digital sialography: imaging and intervention.

Digital subtraction imaging (DSI) has been widely used in angiography but less commonly applied to sialography. Over a 3-year period 109 patients referred for sialography, 42 males and 67 females with a mean age of 44 years (range 8-85 years), were examined using a digital subtraction imaging technique. 13 patients went on to have an interventional procedure, stone removal or duct dilatation. The role of DSI imaging in sialography and its use in facilitating interventional procedures on the salivary glands are discussed.

Traumatic rupture of the thoracic aorta: computed tomography may be a dangerous waste of time.

Traumatic rupture of the thoracic aorta is a justifiably feared condition. Some authors have proposed the use of computed tomography as a non-invasive means of diagnosis. We report two cases where computed tomographic scans were misinterpreted, leading to erroneous diagnoses and inappropriate referrals. The pitfalls of using a cross-sectional imaging technique to diagnose a transverse lesion and the relative ease and accuracy of aortography are discussed.

A review of alternative approaches in the management of iatrogenic femoral pseudoaneurysms.

The management of iatrogenic pseudoaneurysms (IPAs) demands close co-operation between radiologist, vascular surgeon and plastic surgeon. Ideally, each patient should be reviewed employing a team approach. Many IPAs require only observation; those with a volume greater than 6 cm3 will require treatment as spontaneous thrombosis is uncommon. Radiological treatment options include ultrasound guided compression repair (UGCR), embolisation, and covered stenting. Occasionally, these are unsuccessful or contra-indicated, and the vascular surgical approach is discussed in detail. Finally, the role of the plastic surgeon in dealing with skin ischaemia is detailed.

Antenatal ultrasonography in Dunedin: one year's data.

Two thousand and forty-five pregnancies were registered during one calendar year, at the two hospitals in Dunedin. One thousand five hundred and ninety-four liveborn infants and 15 stillborn infants resulted from 1585 pregnancies. Of this group of pregnant women, 74% had one or more ultrasonographic studies (mean number of scans = 1.5). Of the 1609 infants delivered, 0.4% had a major anomaly of the central nervous system, and 0.7% had hydroenphrosis. Four hundred and sixty pregnancies resulted in spontaneous or therapeutic abortion. Ten point nine percent of those women undergoing therapeutic abortion had ultrasonographic studies. It is apparent from this retrospective audit, that antenatal ultrasonography has become almost routine in those women carrying an infant to term. The relative rarity of fetal anomalies is similar to other, larger, series.

Non-operative removal of a parotid duct stone with a balloon angioplasty catheter.

We illustrate a rapid and simple method for removal of a stone from the parotid duct using a balloon angioplasty catheter and digital subtraction imaging. No anaesthesia or surgical intervention is necessary.

Update on endovascular management of arterial occlusive disease.

Although balloon angioplasty is the most widely used technique for treating peripheral vascular disease, developments in endovascular therapies have extended methods of percutaneous vascular intervention. Lasers have been used to recanalize occluded arteries. Mechanical devices can remove obstructions and metallic stents can be placed to keep a vessel open with good long-term patency.

Management plan of post-angiography false aneurysms of the groin.

BACKGROUND: False aneurysm (FA) of the groin is a potentially serious complication of angiographic procedures. We developed a management plan at St. Georgeâs Hospital, and prospectively applied it to 14 consecutive cases over a period of one year. PATIENTS AND METHODS: This report is a prospective cohort study of post-angiography false aneurysms. Fourteen patients with groin FA presented to the vascular team between October 1995 and September 1996 (0.2% of 6926 angiographic procedures). Nine of the 14 patients were fully anticoagulated at the time of treatment. Ultrasound-guided compression (USGC) was tried in 11 patients and was considered inappropriate in three. Embolization was attempted in four patients and surgery was needed in seven patients. RESULTS: The initial angiographic procedure was therapeutic in nine and diagnostic in five patients. The median maximal dimension of the FA was 3 cm (range 2-5). USGC was successful in three patients and failed in eight, seven of them fully anticoagulated at the time of compression. Embolization of the FA was tried in four patients; all were anticoagulated, and embolization was successful. Surgery was required in seven patients, one with infected groin and bleeding, another with FA at the site of a groin graft anastomosis, three with concomitant evacuation of large groin hematomas, one who refused further angiographic procedures, and one who needed prolonged full anticoagulation before the availability of the embolization. The operation was successful in all the patients except one, who died of myocardial infarction 24 hours after successful surgical closure of a FA. CONCLUSION: FA can be managed in a step-wise manner, starting with the noninvasive USGC, embolization and surgery. Surgery is indicated if evacuation of a large hematoma is required, or the presence of infection is suspected. Emergency surgery is indicated for bleeding or imminent rupture.