Emergency endovascular management of acute thoracic aortic pathology A safe and feasible option.

Endovascular repair has revolutionised the emergency treatment of thoracic aortic disease. We report our 10 year experience using this treatment in emergency cases. A prospectively maintained vascular database was analysed. Patients' medical records and CT images stored on the hospital PACS system were also reviewed. Statistical analysis was done using IBM SPSS V21. There were a total of 59 thoracic aortic stenting procedures of which 33 (60% males with a mean age of 58 yrs) were performed for emergency thoracic pathologies: traumatic transection (n = 10), ruptured aneurysm (n = 6), non-traumatic dissection (n = 8) and penetrating aortic ulcer (n = 9). All patients had self-expanding endografts implanted. Two patients required debranching procedures before the endovascular treatment. Thirty-day mortality was 12.1% (4/33). 70% of patients received a single device. There were 7 procedure related complications, 6 requiring re-intervention: thoracotomy and drainage in 2 patients, proximal graft extension in 2, open drainage of groin haematoma in 1 and open repair of a common femoral artery pseudo-aneurysm in one patient. In total 23 patients were transferred from 11 centres nationwide. There were no mortalities or other complications related to patient transfer from peripheral centres. Although acute thoracic aortic pathology is life threatening, appropriate blood pressure management and treatment of associated injuries can result in favourable outcomes. Endovascular repair is a safe and effective treatment option which enables patients to be treated with reduced morbidity and mortality. Transfer of patients with acute pathology to a tertiary centre can safely be performed.

Increased thrombin generation potential in symptomatic versus asymptomatic moderate or severe carotid stenosis and relationship with cerebral microemboli.

INTRODUCTION: The importance of thrombin generation in the pathogenesis of TIA or stroke and its relationship with cerebral microembolic signals (MES) in asymptomatic and symptomatic carotid stenosis has not been comprehensively assessed. METHODS: Plasma thrombin generation parameters from patients with moderate or severe (≥ 50%) asymptomatic carotid stenosis were compared with those from patients with symptomatic carotid stenosis in the early (≤ 4 weeks) and late phases (≥ 3 months) after TIA or stroke in this prospective, pilot observational study. Thrombin generation profile was longitudinally assessed in symptomatic patients with data at each time point. Bilateral transcranial Doppler ultrasound monitoring of the middle cerebral arteries was performed whenever possible to classify patients as MES-positive or MES-negative. RESULTS: Data from 31 asymptomatic, 46 'early symptomatic' and 35 'late symptomatic' patients were analysed. Peak thrombin (344.2 nM vs 305.3 nM; p = 0.01) and endogenous thrombin potential (1772.4 vs 1589.7; p = 0.047) were higher in early symptomatic than asymptomatic patients. Peak thrombin production decreased in symptomatic patients followed up from the early to late phase after TIA or stroke (339.7 nM vs 308.6 nM; p = 0.02). Transcranial Doppler ultrasound data were available in 25 asymptomatic, 31 early symptomatic and 27 late symptomatic patients. Early symptomatic MES-positive patients had a shorter 'time-to-peak thrombin' than asymptomatic MES-positive patients (p=0.04), suggesting a more procoagulant state in this early symptomatic subgroup. DISCUSSION: Thrombin generation potential is greater in patients with recently symptomatic than asymptomatic carotid stenosis, and decreases over time following TIA or stroke associated with carotid stenosis. These data improve our understanding of the haemostatic/thrombotic biomarker profile in moderate-severe carotid stenosis.

Evolution of Carotid Surgical Practice in the last Decade.

Stroke units provide immediate care and appropriate intervention in the evolving stroke. The aims of this study were to review the practice of carotid endarterectomy (CEA) before and after the establishment of a Stroke Unit in St. James's Hospital. Prior to the introduction of the Stroke Unit, 263 CEA's were performed over a five-year period. 139/263 (53%) of these were for symptomatic disease. 229 were performed in the five years since. 179/229 (78%) of these were for symptomatic disease. The 30-day stroke and death rates were < 2% before the introduction of the Stroke Unit, and have remained unchanged. Since the introduction of the Stroke Unit, there has been a slight decrease in the overall number of CEA's performed with a 25% increase in the proportion of endarterectomies performed for symptomatic disease. Despite the reduction in surgery for asymptomatic disease the overall 30-day stroke and death rate remains excellent at 2/229 (2%).

Increased endothelial activation in recently symptomatic versus asymptomatic carotid artery stenosis and in cerebral microembolic-signal-negative patient subgroups.

BACKGROUND AND PURPOSE: von Willebrand factor propeptide (VWF:Ag II) is potentially a more sensitive marker of acute endothelial activation than von Willebrand factor antigen (VWF:Ag). These biomarkers have not been simultaneously assessed in asymptomatic versus symptomatic carotid stenosis patients. The relationship between endothelial activation and cerebral microembolic signals (MESs) detected on transcranial Doppler ultrasound is unknown. METHODS: In this multicentre observational analytical study, plasma VWF:Ag and VWF:Ag II levels in patients with ≥50% asymptomatic carotid stenosis were compared with those from patients with ≥50% symptomatic carotid stenosis in the 'early' (≤4 weeks) and 'late' (≥3 months) phases after transient ischaemic attack or ischaemic stroke. Endothelial activation was also longitudinally assessed in symptomatic patients during follow-up. Transcranial Doppler ultrasound monitoring classified patients as MES-positive or MES-negative. RESULTS: Data from 31 asymptomatic patients were compared with those from 46 early symptomatic and 35 late phase symptomatic carotid stenosis patients, 23 of whom had undergone carotid intervention. VWF:Ag II levels were higher in early (12.8 µg/ml; P < 0.001), late (10.6 µg/ml; P = 0.01) and late post-intervention (10.6 µg/ml; P = 0.038) symptomatic patients than asymptomatic patients (8.9 µg/ml). VWF:Ag levels decreased in symptomatic patients followed up from the early to late phase after symptom onset (P = 0.048). Early symptomatic MES-negative patients had higher VWF: Ag II levels (13.3 vs. 9.0 µg/ml; P < 0.001) than asymptomatic MES-negative patients. CONCLUSIONS: Endothelial activation is enhanced in symptomatic versus asymptomatic carotid stenosis patients, in early symptomatic versus asymptomatic MES-negative patients, and decreases over time in symptomatic patients. VWF:Ag II levels are a more sensitive marker of endothelial activation than VWF:Ag levels in carotid stenosis. The potential value of endothelial biomarkers and concurrent cerebral MES detection at predicting stroke risk in carotid stenosis warrants further study.

Measurement and optimization of patient radiation doses in endovascular aneurysm repair.

The study assessed radiation exposure during EVAR. Two types of patient dose were estimated: effective dose (ED), which allows estimation of radiation risk to the EVAR patient population; and Peak Skin Dose (PSD), which allows us assess the potential for an individual patient to receive a radiation skin injury. An ancillary aim was to examine dose optimization in EVAR procedures. Based on 111 EVAR cases we estimated average ED as 12.4 mSv. Cumulative patient dose in our centre was lower than other studies because the follow up of EVAR patients is based on ultrasound rather than CT. PSD calculated using a published conversion formula closely matched measurements with calibrated gafchromic film. 99% of patients had an estimated PSD of < 2Gy. Results indicate that skin injuries are possible, but very unlikely in EVAR procedures at our centre. EVAR is a high dose procedure and emphasis on dose optimisation is important. We broke the EVAR procedure into 15 steps and, in a phantom study, showed how skin dose changes as procedure steps are varied. The resulting dose matrix has the potential to be used as an educational tool to promote dose optimization.

A critical evaluation of HIPE data.

Resource allocation and planning of future services is dependent on current volumes, making it imperative that procedural data is accurately recorded. We sought to evaluate the effectiveness of the information gathered by the Hospital Inpatient Enquiry (HIPE) system in recording such activity. Five index vascular procedures (open/endovascular abdominal aneurysm repair, carotid endarterectomy, lower limb angioplasty/bypass) were chosen to reflect activity. The Economic and Social Research Institute (ESRI), and HIPE databases were interrogated to obtain the regional and hospital specific figures for the years 2005, 2006 and 2009, and then compared with the prospective vascular database in St James's hospital. Data for 2006 (the most recent year available) shows significant discrepancies between the HIPE and vascular database figures for St James's hospital. The HIPE and database figures respectively for; open aneurysm 13/30 (-50%), endovascular aneurysm 39/31 (+25%), carotid 62/48 (+29%), angioplasty 242/111 (+100%) and bypass 24/10 (+100%) These inaccuracies are likely to be magnified on a regional and national level when pooling data.

Relationship between 'on-treatment platelet reactivity', shear stress, and micro-embolic signals in asymptomatic and symptomatic carotid stenosis.

BACKGROUND: Assessment of 'high on-treatment platelet reactivity (HTPR)' could enhance understanding of the pathophysiology of first or recurrent vascular events in carotid stenosis patients on antiplatelet therapy. METHODS: This prospective, multi-centre study assessed antiplatelet-HTPR status and its relationship with micro-emboli signals (MES) in asymptomatic vs. symptomatic ≥ 50-99% carotid stenosis. Platelet function/reactivity was assessed under 'moderately high shear stress' with the PFA-100® and 'low shear stress' with VerifyNow® and Multiplate® analysers. Bilateral 1-h transcranial Doppler ultrasound of the middle cerebral arteries classified patients as MES + ve or MES - ve. RESULTS: Data from 34 asymptomatic patients were compared with 43 symptomatic patients in the 'early phase' (≤ 4 weeks) and 37 patients in the 'late phase' (≥ 3 months) after TIA/ischaemic stroke. Median daily aspirin doses were higher in early symptomatic (225 mg; P < 0.001), but not late symptomatic (75 mg; P = 0.62) vs. asymptomatic patients (75 mg). There was a lower prevalence of aspirin-HTPR in early (28.6%; P = 0.028), but not late symptomatic (38.9%; P = 0.22) compared with asymptomatic patients (56.7%) on the PFA-100®, but not on the VerifyNow® or Multiplate® (P ≤ 0.53). Early symptomatic patients had a higher prevalence of aspirin-HTPR on the PFA-100® (28.6%) vs. VerifyNow® (9.5%; P = 0.049), but not Multiplate® assays (11.9%, P = 0.10). There was no difference in aspirin-HTPR prevalence between any symptomatic vs. asymptomatic MES + ve or MES - ve subgroup. DISCUSSION: Recently symptomatic moderate-severe carotid stenosis patients had a lower prevalence of aspirin-HTPR than their asymptomatic counterparts on the PFA-100®, likely related to higher aspirin doses. The prevalence of antiplatelet-HTPR was positively influenced by higher shear stress levels, but not MES status.

Endovascular management of thoracic aortic pathology.

BACKGROUND: Endovascular technology has revolutionised the management of abdominal aortic aneurysmal disease but the less frequent occurrence of pathology in the thoracic aorta has meant that evidence demonstrating the primacy of endovascular treatment strategies in this portion of the vessel is less convincing. Herein we summarise the best available evidence to date. METHODS: A comprehensive search of the surgical and radiological literature using the search term 'endovascular thoracic aorta' was conducted. FINDINGS AND CONCLUSIONS: The vast majority of patients treated by thoracic aortic stent grafting have had their treatment outside the context of a randomised trial. While it would seem that endovascular repair is the treatment of choice for the thoracic aorta, the present evidence is based on single centre case series and is anecdotal at best.

Fenestrated endovascular repair of complex aortic aneurysms.

BACKGROUND: Fenestrated endovascular aneurysm repair (FEVAR) provides an endovascular solution for patients with large abdominal aortic aneurysms and challenging neck anatomy in addition to repair of endoleaks and pseudoaneurysms. This article reports the midterm outcomes of FEVAR from a single-tertiary referral centre in Ireland. METHODS: From 2006 to 2012, nine consecutive asymptomatic patients with neck anatomy unfavourable for standard EVAR underwent endovascular repair with a customised fenestrated Zenith stent graft. An additional three patients had fenestrated grafts for repair of pseudoaneurysms (n = 2) following open AAA repair and a type I endoleak (n = 1). All patients were prospectively enrolled in a computerised database. Outcomes including mortality, morbidity, renal function, target vessel patency, endoleak and reintervention were analysed. FINDINGS: The mean age and aneurysm size in the primary repair group were 74 years (65-84 years) and 6 cm (5-8.3 cm), respectively, and in the secondary repair group, the mean age was 66 years (61-75 years). No procedures required open conversion, and no visceral arteries were lost. On completion angiography, two patients in group 1 had a type I endoleak and one had a type III endoleak. There were no endoleaks in the secondary repair group. Follow-up ranged from 30 days to 6 years. There was one death within 30 days (8 %) and two deaths at 3 years from non-aneurysm-related causes. Six patients required secondary interventions. Three patients had a transient post-operative creatinine rise of >30 %. CONCLUSION: Our study supports FEVAR as a feasible and effective therapy in the management of patients with complex aortic aneurysms.

Arterial closing pressure correlates with diastolic pseudohypertension in the elderly.

BACKGROUND: Pseudohypertension has frequently been reported in the elderly population, with the diastolic measurement being the most frequent source of error. There is no satisfactory noninvasive method of calculating the error in the blood pressure reading. We investigated the role of arterial closing pressure in the diagnosis of diastolic pseudohypertension. METHODS: Indirect and direct blood pressure were measured in 24 elderly patients. Brachial artery closure was visualized by ultrasound in all subjects. Arterial closing pressure (ACP) was recorded as zero if the vessel was seen to close spontaneously when it was isolated from central arterial pressure. If the vessel did not close spontaneously, a water cuff was applied externally over the artery and the additional pressure required to close it was recorded. RESULTS: Diastolic pseudohypertension was noted in 8 subjects. Spontaneous closure of the brachial artery occurred in the 16 without pseudohypertension; i.e., ACP = 0. Additional pressure of the water cuff (range: 30-158 mm Hg) was required to collapse the artery (ACP) in those with diastolic pseudohypertension. ACP correlated with the extent of diastolic pseudohypertension (range: 5-17 mm Hg); r = .85, p < .001). CONCLUSION: We propose that ACP may be used to diagnose the presence and extent of pseudohypertension.

Stenosis following carotid endarterectomy. Its implication in management of asymptomatic carotid stenosis.

Carotid endarterectomy is established in the treatment of atherosclerosis of the carotid bifurcation, but the incidence of restenosis and the role of endarterectomy in the management of asymptomatic carotid stenosis are variable. During a four-year period, we performed 80 endarterectomies of the internal carotid artery in 73 patients. Patients were prospectively studied by means of Doppler ultrasonography in combination with real-time spectral analysis to determine the incidence of restenosis postoperatively. A concomitant study of 116 patients with 79 asymptomatic carotid stenoses was undertaken. We found a 12.5% incidence of stenosis following carotid endarterectomy and a 3% risk of transient neurologic deficit in the patients with asymptomatic carotid stenoses.

Alpha 2C-adrenoceptors mediate contractile responses to noradrenaline in the human saphenous vein.

We have investigated the subtype of alpha 2-adrenoceptor mediating isometric contractions of human saphenous vein in comparison with alpha 2-adrenoceptor ligand binding sites. Postjunctional alpha 2-adrenoceptors in the human saphenous vein were investigated in terms of the ability of alpha 2-adrenoceptor antagonists to shift the contractile potency of noradrenaline. The following antagonists were employed (potencies, pKB, in human saphenous vein in parentheses): chlorpromazine (6.98 +/- 0.24), BDF 8933 (7.60 +/- 0.06), prazosin (6.62 +/- 0.15), ARC 239 (7.19 +/- 0.15), yohimbine (7.23 +/- 0.09), HV 723 (7.52 +/- 0.14), WB 4101 (7.90 +/- 0.06), SKF 104078 (6.55 +/- 0.08), BRL 44408 (5.72 +/- 0.21). Antagonist potency at postjunctional alpha 2-adrenoceptors was correlated with antagonist affinity at alpha 2-adrenoceptor ligand binding sites in membranes of human platelet (alpha 2A), rat kidney (alpha 2B) and Sf9 cells expressing human recombinant receptors (alpha 2C), labelled with [3H]yohimbine. The correlation with the postjunctional alpha 2-adrenoceptor mediating contraction of the human saphenous vein was best for the human recombinant alpha 2C-adrenoceptor ligand binding site (r = 0.92, n = 8, P < 0.001), as compared to correlations with the alpha 2B-adrenoceptor ligand binding site of rat kidney (r = 0.62, n = 8, n.s.) and with the alpha 2A-adrenoceptor ligand binding site of human platelet (r = 0.23, n = 8, n.s.). It is concluded that the functional postjunctional alpha 2-adrenoceptor mediating contractions of the human saphenous vein closely resembles the human recombinant alpha 2C-adrenoceptor ligand binding site.

Ultrasonic screening for the detection of abdominal aortic aneurysms.

Detection of aortic aneurysms before they rupture is imperative if the mortality rate from this disease is to be reduced. Although large aneurysms frequently are palpable, small aneurysms--especially in obese patients--are seldom recognized on physical examination. Ultrasound, which is noninvasive, relatively inexpensive, and nearly 100 per cent accurate in identifying the presence or absence of aneurysms, is well suited to screening. In high-risk populations (patients over the age of 50 with coronary artery or peripheral vascular disease), ultrasonic screening is probably cost-effective.

Low dose intraarterial thrombolysis with tissue plasminogen activator: does it deliver as promised?

The widespread use of intraarterial thrombolytic therapy has been based on perceived benefits over operative treatment and the downgrading of the magnitude of subsequent surgery. Thirty-three patients who had thrombolysis for peripheral artery occlusion were retrospectively analyzed at St. James's Hospital from 1991 to 1997. One patient received streptokinase unsuccessfully. Five other patient's records were inadequate for analysis. Twenty-seven patient's notes were analyzed for risk, duration of occlusion, duration of treatment, dosage of tissue plasminogen activator (tPA) and conduits thrombolysed. There were 15 males and 12 females. The mean age was 62 years (range, 20-87). Fourteen were current or reformed smokers. Five were diabetic. Indications for treatment included acute graft occlusion (n=13), embolus (n=6), and primary and secondary arterial thrombosis (n=8). Duration of occlusion was less than 24 hours in seven, 1 to 7 days in ten, and more than 7 days in ten patients. Twelve (44.44%) patients had complete clot lysis, four (14.81%) had partial clearance, and 11 (40.74%) remained occluded. Eight (29.63%) had serious complications including one death. Eighteen (66.66%) patients needed further surgical intervention to maintain graft patency. Data were analyzed using the chi-square and pooled t test. No significant difference was observed in results from thrombolysis from different conduits, gender, etiology, or smoking history. Increased duration of tPA administration was associated with an increased risk of failure. Administration of total dosages greater than 60 mg was associated with a higher risk of failure. Diabetics had a poor outcome (p=0.0520). Only 44 % of patients successfully underwent lysis. A primary surgical option may be a more sensible course than lysis, given that the vast majority of patients ended up having surgery anyway.

Stenosis following carotid endarterectomy.

Carotid endarterectomy is well established in the treatment of selected cases of atherosclerosis of the carotid bifurcation but the incidence of restenosis is unknown. During a four year period 80 endarterectomies of the internal carotid artery were performed in 73 patients. Post-operatively we studied our patients prospectively by means of Doppler ultrasound in combination with real time spectral analysis and where indicated digital venous angiography to determine the incidence of restenosis. We report a 12.5% incidence of stenosis following carotid endarterectomy with a 1% incidence of symptomatic restenosis. We therefore question the role of carotid endarterectomy in the treatment of asymptomatic carotid stenosis.

Measurement of arterial closing pressure.

It has been suggested that certain artifacts in blood pressure measurement by auscultation stem from stiffness of the tissues underneath the pressure cuff, resulting in a component of cuff pressure being required to overcome resistance to brachial artery collapse. This paper describes a technique for measuring the pressure required to collapse a segment of the brachial artery which has been isolated from central arterial pressure. This measurement is termed the arterial closing pressure. In a study of eleven elderly subjects, the artery collapsed spontaneously (zero closing pressure) after being isolated from central pressure in seven subjects. The remaining four required external pressures ranging from 4.6 to 10.7 kPa (35 to 81 mmHg) in order to collapse the artery. Thus arterial closing pressure may frequently be a significant fraction of arterial blood pressure in the elderly population, and may contribute to error in the measurement of blood pressure by auscultation. Arterial closing pressure may be a useful tool for investigating the origin of differences between indirect and direct blood pressure measurements, and also in the investigation of spontaneous arterial closure.

Observing the brachial artery through a pressure cuff.

A technique is described which enables ultrasonic imaging of the brachial artery whilst pressure is applied via a pressure cuff. This involves a new instrument--a sphygmomanometer, which uses water as opposed to air as the pressure medium, in order to permit ultrasonic imaging through the cuff. The technique was found to be acceptable in the clinical setting, and gave a measurement of the systolic blood pressure which correlated with the conventional cuff measurement in eleven elderly subjects (r = 0.89, p < 0.001). The technique should have an important role to play in studying the origin of differences which occur between direct and indirect blood pressure measurements.

New approaches in the medical management of venous ulceration.

This literature survey of the medical treatment of venous ulcers of the lower extremities discusses five classes of agents: (1) fibrinolytics, (2) hydroxyrutosides, (3) prostaglandins, (4) methylxanthines, and (5) others. The authors conclude that all these agents require further research.