S.D. Goode

Laser and Radiofrequency Ablation Study (LARA study): A Randomised Study Comparing Radiofrequency Ablation and Endovenous Laser Ablation (810 nm)

OBJECTIVES There have been few randomised studies comparing Radiofrequency Ablation(RFA) with other endovenous techniques. The primary aim of this study was to determine whether RFA of the great saphenous vein (GSV) was associated with less pain and bruising than endovenous laser ablation (EVLA). MATERIALS AND METHODS This trial had two cohorts--patients with bilateral GSV incompetence causing varicose veins (VV) and those with unilateral GSV VVs. In total 87 legs were treated in this study. Limbs in the bilateral group were treated with RFA in one leg and EVLA in the other. In the unilateral group limbs were randomised to RFA or EVLA. RFA was performed using the Celon RFiTT system (Teltow, Germany). EVLA was performed using an 810nm Laser (Biolitec AG, Germany). Phlebectomies were performed as required. Primary endpoints were patient assessed pain and bruising measured by visual analogue scale (VAS). Secondary endpoints were patency assessed by duplex ultrasound at 6 weeks and 6 months. RESULTS In the bilateral group, RFA resulted in significantly less pain than EVLA on days 2-11 postoperatively. RFA also resulted in significantly less bruising than EVLA on days 3-9. There were no significant differences in mean post operative pain, bruising and activity scores in the unilateral group. Both RFA and EVLA resulted in occlusion rates of 95% at 10 days postoperatively. CONCLUSIONS RFA was less painful for patients than EVLA and produced less bruising in the postoperative period with comparable success rates but there was no difference in the unilateral group.

Precision of Cerebrovascular Reactivity Assessment with Use of Different Quantification Methods for Hypercapnia Functional MR Imaging

BACKGROUND AND PURPOSE: Tools for noninvasive mapping of hemodynamic function including cerebrovascular reactivity are emerging and may become clinically useful to predict tissue at hemodynamic risk. One such technique assesses blood oxygen level–dependent (BOLD) MR imaging contrast in response to hypercapnia, but the reliability of its quantification is uncertain. The aim of this study was to prospectively investigate the intersubject and interhemispheric variability and short-term reproducibility of hypercapnia functional MR imaging (fMRI) in healthy volunteers and to assess the effects of different methods of quantification and normalization. MATERIALS AND METHODS: Sixteen healthy volunteers, (7 women and 9 men) underwent hypercapnia fMRI with a clinical 1.5T scanner; 8 underwent scanning twice. We determined BOLD amplitude changes using a visually defined block design or automated regression to end-tidal (ET) carbon dioxide (CO2). Absolute percent signal intensity changes (PSC) were extracted for whole-brain, gray matter, and middle cerebral artery territory, and also normalized to ETCO2 change. Intersubject and intrasubject (between hemispheres and sessions) coefficients of variation (COV) were derived. We assessed the effects of different quantification methods on reproducibility indices using the t test and U tests. RESULTS: The mean change in ETCO2 was 7.8 ± 3.3 mm Hg. Averaged BOLD increases varied from 2.54% to 2.92%. Short-term reproducibility was good for absolute PSC (4.8% to 10%) but poor for normalized PSC (range, 24% to 27% COV). Intersubject reproducibility varied between 11% and 23% for absolute PSC and, again, was poorer for normalized data (32% to 39%). Interhemispheric reproducibility of absolute PSC was excellent ranging between 1.24 and 2.16% COV. CONCLUSIONS: In conclusion, quantification of cerebrovascular reactivity with use of hypercapnia fMRI was found to have good between-session and very good interhemispheric reproducibility. The technique holds promise as a diagnostic tool, especially for sensitive detection of unilateral disease.

Plaque Hemorrhage Is a Marker of Thromboembolic Activity in Patients with Symptomatic Carotid Disease

PURPOSE To assess whether carotid plaque hemorrhage depicted with magnetic resonance (MR) imaging was associated with thromboembolic activity as assessed with transcranial Doppler imaging. MATERIALS AND METHODS The local research ethics committee approved the study, and all patients gave informed written consent. Between April 2005 and December 2006, patients with high-grade symptomatic carotid stenosis were prospectively recruited. All underwent MR imaging of the carotid arteries for plaque hemorrhage and diffusion-weighted imaging of the brain. Transcranial Doppler imaging of the symptomatic carotid artery was performed over 1 hour to assess the presence of microembolic signal. To determine the relationship between the presence of plaque hemorrhage and diffusion-weighted imaging-positive signal and presence of microembolic signal, a logistic regression analysis was performed. RESULTS Fifty-one patients (23 women and 28 men; mean age ± standard deviation, 72 years ± 11) underwent complete MR imaging; 46 (86%) of these patients underwent complete transcranial Doppler imaging. In 32 (63%) patients, there was plaque hemorrhage in the index carotid artery. The presence of plaque hemorrhage increased the risk for ipsilateral abnormalities at diffusion-weighted imaging (odds ratio, 6.2 [95% confidence interval: 1.7, 21.8]; P < .05). Multiple diffusion-weighted imaging-depicted abnormalities of multiple ages were present exclusively in patients with plaque hemorrhage shown at MR imaging (12 of 32 [38%] patients with plaque hemorrhage versus none of 19 patients without plaque hemorrhage; P < .05). The presence of plaque hemorrhage also increased the presence of microembolic signal (odds ratio, 6.0 [95% confidence interval: 1.8, 19.9]; P = .003). CONCLUSION In patients with carotid plaque hemorrhage demonstrated at MR imaging, there was increased spontaneous microembolic activity at transcranial Doppler imaging and cerebral ischemic lesion patterns suggestive of recurrent embolic events; these findings suggest that plaque hemorrhage shown at MR imaging might be a marker of thromboembolic activity and further validate the usefulness of carotid imaging in identifying patients with active carotid arterial disease.

The Importance of Anatomical Suitability and Fitness for the Outcome of Endovascular Repair of Ruptured Abdominal Aortic Aneurysm

INTRODUCTION Endovascular repair of aortic aneurysm (EVAR) has a lower mortality than open repair. The aim of this study was to assess mortality from EVAR for emergency AAA repair and the impact of fitness for operation and adverse anatomy. METHODS One-hundred and forty two patients who had EVAR for a ruptured AAA (80, REVAR) or a symptomatic AAA (62, SEVAR) between 1994 and 2007 in a single specialist endovascular centre were reviewed. Fitness for surgery was assessed by Hardmans index (age>76, loss of consciousness, Hb<9.0, Cr>190, ischaemic ECG). CT scans were reviewed, compared with operative images and operation notes for adverse anatomy. Details of perioperative complications, and outcome were recorded. RESULTS Overall mortality at 24-h, 30-days and one year were, respectively: 17%, 36%, 50% for REVAR and 5%, 8%, 23% for SEVAR. Overall adverse anatomy increased 30-day mortality. Hardmans index of three or more increased mortality HR=2.59 (1.24-5.41), p=0.01. On Cox regression Univariate analysis increasing Hardmans index score and adverse anatomy increased the overall mortality over time. In multivariate Cox regression analysis (controlled for the Hardmans index) adverse anatomy was associated with significant increase in graft related mortality. CONCLUSION The use of EVAR is feasible in patients who present with a ruptured or acutely symptomatic AAA. Care must be taken not to extend anatomical or clinical guidelines.

Carotid Endarterectomy Improves Cerebrovascular Reserve Capacity Preferentially in Patients with Preoperative Impairment as Indicated by Asymmetric BOLD Response to Hypercapnia

PURPOSE In patients with symptomatic carotid artery disease the predominant mechanism causing ischaemic injury is considered to be thromboembolic, however compromise of cerebral haemodynamics is considered to be a significant factor. Removal of the embolic source is accepted as the major benefit from carotid endarterectomy (CEA), however improvement in cerebral haemodynamics may be another beneficial outcome as suggested by transcranial doppler (TCD). Blood oxygen level-dependent (BOLD) hypercapnia functional magnetic resonance imaging (fMRI) can be used to map the cerebrovascular reserve (CVR). The aim of this study was to assess the effects of carotid surgery on cerebral haemodynamics in patients with carotid artery disease using a hypercapnia BOLD fMRI and assessment of hemispheric asymmetry. MATERIALS AND METHODS Seventeen patients with symptomatic internal carotid artery stenosis were scanned using a clinical 1.5T MR scanner. Scanning was done immediately prior to and between 4 and 8 weeks after CEA. 10% carbon dioxide was administered to achieve transient episodes of hypercapnia. The data was analyzed using FMRIB Software Library (FSL) software to derive percentage signal change (PSC) for the grey matter of the middle cerebral artery (MCA-GM) territory for both hemispheres. MCA-GM PSC was furthermore normalized to the contralateral hemisphere to derive an Hemispheric Asymmetry Index (hAI) for all patients pre- and postoperatively. RESULTS Ipsilateral GM CVR improved significantly following CEA (2.47% preoperatively vs. 2.73% postoperatively, p=0.038). There was no change in CVR in the contralateral grey and white matter MCA territories (p=0.27, p=0.1). Also, the hAI was significantly more shifted to the ipsilateral hemisphere after CEA (preoperative hAI -0.56, vs. -3.90 postoperatively, p=0.02). Patients with an impaired hAI preoperatively were found to show the greatest improvement in PSC and hAI following CEA (p=0.007). CONCLUSIONS CEA resulted in improved CVR in patients with carotid artery disease as shown by the absolute and hemispheric asymmetry of BOLD response to hypercapnia.. These findings show that benefits from recanalisation may go beyond removal of the embolic source, by improving the cerebrovascular reserve. Moreover, hypercapnia BOLD fMRI may be a useful clinical tool in predicting this therapeutic potential in patients with severe carotid artery disease.

Leukoaraiosis Predicts the Need for Intraoperative Shunt Placement During Carotid Endarterectomy

OBJECTIVES White matter hyperintense lesions (WMHLs) are related to age, hypertension, and ischemia. They increase the risk of stroke in natural history and perioperatively during carotid endarterectomy. This may reflect an association with impaired cerebral hemodynamics. Hence, the authors studied whether ipsilateral WMHLs predict shunt requirement on clamping as an indicator of hemodynamic compromise. DESIGN AND METHODS A retrospective analysis was done in patients with symptomatic and severe carotid stenosis (>60%). Ipsilateral WMHL volumes were calculated from magnetic resonance imaging scans and association studied with the requirement of an intraoperative shunt. RESULTS Seventy patients were included. Twelve (17%) patients required shunting and 2 developed perioperative strokes. Patients requiring shunting had a larger WMHL volume (adjusted means = 16.2 +/- 2.9 mL compared with 8.7 +/- 1.2 mL for the nonshunt group; P = .020). CONCLUSIONS Ipsilateral WMHL volume is a significant predictive factor for shunt requirement during carotid endarterectomy. This may reflect cerebral hemodynamic compromise.

Cerebral misery perfusion diagnosed using hypercapnic blood-oxygenation-level-dependent contrast functional magnetic resonance imaging: a case report

IntroductionCerebral misery perfusion represents a failure of cerebral autoregulation. It is an important differential diagnosis in post-stroke patients presenting with collapses in the presence of haemodynamically significant cerebrovascular stenosis. This is particularly the case when cortical or internal watershed infarcts are present. When this condition occurs, further investigation should be done immediately.Case presentationA 50-year-old Caucasian man presented with a stroke secondary to complete occlusion of his left internal carotid artery. He went on to suffer recurrent seizures. Neuroimaging demonstrated numerous new watershed-territory cerebral infarcts. No source of arterial thromboembolism was demonstrable. Hypercapnic blood-oxygenation-level-dependent-contrast functional magnetic resonance imaging was used to measure his cerebrovascular reserve capacity. The findings were suggestive of cerebral misery perfusion.ConclusionsBlood-oxygenation-level-dependent-contrast functional magnetic resonance imaging allows the inference of cerebral misery perfusion. This procedure is cheaper and more readily available than positron emission tomography imaging, which is the current gold standard diagnostic test. The most evaluated treatment for cerebral misery perfusion is extracranial-intracranial bypass. Although previous trials of this have been unfavourable, the results of new studies involving extracranial-intracranial bypass in high-risk patients identified during cerebral perfusion imaging are awaited.Cerebral misery perfusion is an important and under-recognized condition in which emerging imaging and treatment modalities present the possibility of practical and evidence-based management in the near future. Physicians should thus be aware of this disorder and of recent developments in diagnostic tests that allow its detection.

Impaired Cerebrovascular Reactivity Predicts Recurrent Symptoms in Patients with Carotid Artery Occlusion: A Hypercapnia BOLD fMRI Study

BACKGROUND AND PURPOSE: A key factor in predicting recurrent ischemic episodes in patients with carotid artery occlusion is the presence of hemodynamic impairment. There is, however, no consensus on how to best assess this risk in terms of imaging modalities or thresholds used. Here we investigated whether a predefined threshold of hemispheric asymmetry in hypercapnia fMRI predicts recurrent symptoms in patients with carotid artery occlusion. MATERIALS AND METHODS: We studied 23 patients (2 women) with a mean age of 67.5 ± 9 years. Patients were assessed for recurrent ischemic events until lost to follow-up, study end, death, or recurrent ischemic event. Hypercapnia fMRI was used to assess the cerebrovascular reserve and quantify the percentage signal change in GM in the MCA territory and the hemispheric asymmetry index. Kaplan-Meier survival analysis and log-rank tests were performed to assess differences between patients with normal or abnormal hemispheric indices. RESULTS: The median follow-up was 20 months. During this period, 8 patients experienced recurrent events, and 15 did not. The percentage signal change in GM in the MCA territory was significantly decreased in those patients with recurrent events compared with those without (2.39 ± 0.22 versus 2.70 ± 0.42, P = .032). The normal hemispheric index predicted event-free survival during follow-up (median, 20 months) for both the combined outcome (recurrent events and/or death, log-rank, P = .034) and recurrent retinal or ipsilateral ischemic events only (log-rank, P = .012). CONCLUSIONS: The hemispheric asymmetry index derived from hypercapnia fMRI showed hemodynamic impairment in more than half of the studied patients with carotid occlusion, and those patients showed a higher risk of recurrent ischemic symptoms.