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Tjun Tang

Publications and source records attributed to Tjun Tang.

10 recordsLinked to original sources
PubMed2006

Assessment of inflammatory burden contralateral to the symptomatic carotid stenosis using high-resolution ultrasmall, superparamagnetic iron oxide-enhanced MRI.

BACKGROUND AND PURPOSE: It is well known that the vulnerable atheromatous plaque has a thin, fibrous cap and large lipid core with associated inflammation. This inflammation can be detected on MRI with use of a contrast medium, Sinerem, an ultrasmall superparamagnetic iron oxide (USPIO). Although the incidence of macrophage activity in asymptomatic disease appears low, we aimed to explore the incidence of MRI-defined inflammation in asymptomatic plaques in patients with known contralateral symptomatic disease. METHODS: Twenty symptomatic patients underwent multisequence MRI before and 36 hours after USPIO infusion. Images were manually segmented into quadrants, and the signal change in each quadrant was calculated after USPIO administration. A mixed mathematical model was developed to compare the mean signal change across all quadrants in the 2 groups. Patients had a mean symptomatic stenosis of 77% compared with 46% on their asymptomatic side, as measured by conventional angiography. RESULTS: There were 11 (55%) men, and the median age was 72 years (range, 53 to 84 years). All patients had risk factors consistent with severe atherosclerotic disease. All symptomatic carotid stenoses had inflammation, as evaluated by USPIO-enhanced imaging. On the contralateral sides, inflammatory activity was found in 19 (95%) patients. Contralaterally, there were 163 quadrants (57%) with a signal loss after USPIO when compared with 217 quadrants (71%) on the symptomatic side (P=0.007). CONCLUSIONS: This study adds weight to the argument that atherosclerosis is a truly systemic disease. It suggests that investigation of the contralateral side in patients with symptomatic carotid stenosis can demonstrate inflammation in 95% of plaques, despite a mean stenosis of only 46%. Thus, inflammatory activity may be a significant risk factor in asymptomatic disease in patients who have known contralateral symptomatic disease. Patients with symptomatic carotid disease should have their contralateral carotid artery followed up.

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PubMed2006

How critical is fibrous cap thickness to carotid plaque stability? A flow-plaque interaction model.

BACKGROUND AND PURPOSE: Acute cerebral ischemic events are associated with rupture of vulnerable carotid atheroma and subsequent thrombosis. Factors such as luminal stenosis and fibrous cap thickness have been thought to be important risk factors for plaque rupture. We used a flow-structure interaction model to simulate the interaction between blood flow and atheromatous plaque to evaluate the effect of the degree of luminal stenosis and fibrous cap thickness on plaque vulnerability. METHODS: A coupled nonlinear time-dependent model with a flow-plaque interaction simulation was used to perform flow and stress/strain analysis in a stenotic carotid artery model. The stress distribution within the plaque and the flow conditions within the vessel were calculated for every case when varying the fibrous cap thickness from 0.1 to 2 mm and the degree of luminal stenosis from 10% to 95%. A rupture stress of 300 kPa was chosen to indicate a high risk of plaque rupture. A 1-sample t test was used to compare plaque stresses with the rupture stress. RESULTS: High stress concentrations were found in the plaques in arteries with >70% degree of stenosis. Plaque stresses in arteries with 30% to 70% stenosis increased exponentially as fibrous cap thickness decreased. A decrease of fibrous cap thickness from 0.4 to 0.2 mm resulted in an increase of plaque stress from 141 to 409 kPa in a 40% degree stenotic artery. CONCLUSIONS: There is an increase in plaque stress in arteries with a thin fibrous cap. The presence of a moderate carotid stenosis (30% to 70%) with a thin fibrous cap indicates a high risk for plaque rupture. Patients in the future may be risk stratified by measuring both fibrous cap thickness and luminal stenosis.

Atherosclerosis↗
PubMed2005

Waiting time for primary hip replacement--a matter of priority.

INTRODUCTION: Government reformers often allocate priority to patients based on the time spent on a waiting list. This may conflict with the surgeon's agenda of priority based upon clinical need. METHODS: We reviewed 125 consecutive patients who were awaiting total hip replacement on one consultant's surgical waiting list. We assessed hip pain and function by using a modified Harris Hip Score, which was calculated at the time of addition to the surgical waiting list, at pre-operative assessment and at 6 months' follow-up. RESULTS: Analysis showed that although many patients (31.2%) deteriorate on a surgical waiting list, not all do so. Some stay clinically the same (53.8%) and some improve (15%) while awaiting surgery. CONCLUSION: Patients should not be prioritised solely on the length of time they have spent on a surgical waiting list. Waiting lists should be continually reviewed.

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PubMed2003

Enteral stenting in 21 patients with malignant gastroduodenal obstruction.

Placement of an enteral stent is emerging as an effective alternative to surgery for symptomatic relief in patients with malignant gastric outflow and duodenal obstruction. We report experience in a series of patients who had the Wallstent enteral prosthesis inserted. 21 consecutive patients with inoperable obstruction, median age 75 years, had twenty-three procedures for insertion of the Wallstent under fluoroscopic guidance. Stent implantation was successful in 18 patients (86%), all of whom gained relief from nausea and vomiting. There were no short-term complications. Median survival after the procedure was four months (longest ten months), and no deaths were related to insertion. The efficacy and lack of complications in this series support use of the endoscopically placed stent for palliative management of malignant upper gastrointestinal obstruction.

Adult↗
PubMedDate not supplied

Surgical repair of bilateral profunda femoris artery aneurysms.

True aneurysms of the profunda femoral artery are a rare arteriopathy. Few cases have been described in the literature. They are prone to spontaneous rupture and carry significant morbidity, including loss of limb. In light of this, elective repair of profunda femoris aneurysms at the time of detection is the preferred course of action. Surgical repair should include reconstruction of the profunda circulation, in addition to exclusion of the aneurysm to prevent distal ischemia. In this report, we describe the case of a gentleman in whom bilateral profunda femoris artery aneurysms were detected during angiography to investigate his intermittent claudication. Surgical repair involved both exclusion of the aneurysms and bilateral vascular reconstruction.

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