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Biomedical subjects

M G Cowling

Publications and source records attributed to M G Cowling.

17 recordsLinked to original sources
PubMed2004

The relationship between plasma MMP-1, -7, -8 and -13 levels and embolic potential during carotid endoluminal intervention.

BACKGROUND: Patients undergoing carotid endoluminal intervention are at risk of embolic stroke even with the use of distal protection devices. Matrix metalloproteinases (MMPs) have been implicated as a causal factor in plaque instability leading to spontaneous embolisation. We investigated whether plasma MMP levels correlated with the embolisation during carotid endoluminal intervention. METHODS: Thirty circumferentially intact carotid endarterectomy specimens were subjected to a standardised angioplasty procedure in a pulsatile ex vivo model. Emboli collected in a series of distal filters were counted and sized. Plasma samples were collected pre-operatively and analysed for MMP-7 and MMP-8 levels using Western immunoblotting. MMP-1 and MMP-13 levels were determined using ELISA. Emboli number and maximum size were correlated with plasma levels of the MMPs using Spearmans rank. RESULTS: Total MMP-8 levels were related to maximum embolus size (r=0.442, p=0.005) but not emboli number (r=0.342, p=0.052). MMP-1, -7 and -13 were not correlated with either emboli number or with maximum embolus size. CONCLUSION: Pre-operative plasma MMP-8 levels are related to the size of emboli from plaques during carotid endovascular intervention. Further in vivo studies need to be performed to assess the importance of this finding. There is potential for development of plasma markers to identify those patients at greater risk of embolic stroke during carotid endoluminal intervention.

Aged↗
PubMed2003

Carotid angioplasty in a pulsatile flow model: factors affecting embolic potential.

OBJECTIVES: Carotid endoluminal intervention is an alternative to surgery but carries a risk of embolic stroke even with distal protection devices. We investigated the clinical features and degree of stenosis related to number and size of emboli during carotid angioplasty. DESIGN: An experimental ex vivo study. MATERIALS: An ex vivo pulsatile flow model was used in which temperature, velocity, flow, pressure and viscosity characteristics were designed to simulate the carotid circulation. METHODS: Carotid endarterectomy specimens excised as intact cylinders (n = 28) were subjected to a standardised angioplasty procedure using radiological guidance. Emboli collected in filters placed distally were counted and sized using microscopy. RESULTS: Median number of emboli during angioplasty was 133 (range 15-1331). Median size of the largest embolus was 700 microns (range 75-2400). Severity of stenosis correlated with increased maximum size (r = 0.55, p = 0.012). Statin therapy >4 weeks pre-operatively was associated with reduced emboli number and size (54 (range 15-748) vs 247 (range 37-1331) [p = 0.023] and 400 microm (range 75-2400) vs 1300 microm (range 600-2200) [p = 0.022]). CONCLUSIONS: In this model a wide range of emboli number and size were produced. Number and size of embolic particles were highest in patients with high-grade stenoses not receiving statin therapy.

Aged↗
PubMed2001

Internal stenting in malignant biliary obstruction.

Internal stenting in inoperable malignant biliary obstruction plays an important role in patient management. Surgical bypass may still be undertaken where there is also duodenal obstruction, though the need for gastroenterostomy may be reduced with the increasing use of metallic stents for the relief of malignant gastric outlet obstruction. Stents may be placed endoscopically or percutaneously, though in most centers the endoscopic route is usually tried first, with the percutaneous route being reserved for endoscopic failures. Plastic and self-expanding metallic biliary stents are available, each with its own advantages and disadvantages. In general, longer periods of patency are observed with metallic stents, though they are more expensive. Plastic stents can be changed endoscopically relatively easily when they have blocked, and in practice it is common for plastic stents to be inserted via this route for initial biliary drainage. If there is prolonged survival thereafter, many workers insert a metallic stent in an attempt to reduce the number of interventions required. If the percutaneous route is being employed, the histologic diagnosis has been confirmed, and the malignancy is inoperable, our practice is to use a self-expanding metallic stent, as the delivery system is relatively small and subsequent occlusion less likely.

Biliary Tract Neoplasms↗
PubMed2000

Stenting in the oesophagus.

Self-expanding metallic stents have assumed increasing importance in the palliative treatment of malignant dysphagia in recent years. This is most commonly the result of inoperable oesophageal cancer, but may also be the result of extrinsic compression on the oesophagus by other malignant masses. Stents are also occasionally used as a last resort in benign disease.

Carcinoma↗
PubMed1999

Self-expanding metallic stents in the management of pyloric dysfunction after gastric pull-up operations.

The purpose of this paper is to report the use and benefits of self-expanding metallic stents employed in pyloric dysfunction. Four patients treated with oesophagectomy and gastric pull-up for oesophageal carcinoma failed to respond to balloon dilatation for pyloric dysfunction. Three of the patients were thought to have residual tumour at sites remote from the pylorus prior to stenting, but the fourth, who had undergone surgery 8 years previously, was thought to be cured. All were treated with self-expanding metallic stents. All four patients responded well with resolution of their symptoms. Over a mean follow-up of 6 months there has been no recurrence of symptoms. Stent insertion represents a potentially valuable method of treatment in patients with post-surgical pyloric dysfunction in whom simple balloon dilatation has failed.

Aged↗
PubMed1998

Management of malignant oesophageal obstruction with self-expanding metallic stents.

BACKGROUND: The use of self-expanding metal stents for palliation of malignant dysphagia is increasing. Experience in 70 patients was reviewed with respect to the value of stenting and management of the complications encountered. METHODS: Oesophageal stents were inserted in 70 patients (42 men) of mean age 73 years with malignant oesophageal obstruction. Data regarding stent insertion and degree of dysphagia were gathered prospectively. RESULTS: Seventy-six stents were placed in 70 patients. By the end of the study 57 patients had died and 13 were still alive. Three patients died within 3 days of stent insertion and dysphagia was relieved in 64 of the 67 patients remaining. Stent migration, tumour ingrowth and overgrowth, and food impaction were encountered during follow-up in eight patients. CONCLUSION: Insertion of self-expanding metal stents for the palliation of malignant oesophageal obstruction is a successful therapy which can be carried out with relative ease. Palliation of dysphagia with an appropriate stent can be expected in up to 95 per cent of patients.

Aged↗
PubMed1998

Radiological management of oesophageal strictures.

Interventional radiologists have an increasing role in managing oesophageal strictures. Fluoroscopically-guided balloon dilatation can relieve dysphagia in patients with benign strictures in about 95% of cases with minimal associated complications. Over 95% of patients with inoperable malignant oesophageal strictures can be successfully palliated with self-expanding metallic stents.

Catheterization↗
PubMed1995

Benign chest wall lipoblastoma of infancy producing underlying bone enlargement.

We report a case of a chest wall lipoblastoma first presenting in a 6-month-old infant. Clinical presentation was with a posterior chest wall mass. Chest X-ray showed expansion of the posterior ribs on the left, a feature not previously described in this condition. CT scanning delineated a mass of predominantly fat attenuation, which was invading between the ribs to line the extra-pleural space, and was causing compression and atrophy of muscles locally. There were two recurrences requiring further surgery. Histology showed a well-differentiated lipoblastoma.

Female↗
PubMed1995

A potential pitfall in bronchial artery embolization.

Two cases of patients with massive haemoptysis undergoing bronchial arteriography are described. Both had collateral vessels which filled the right subclavian artery from the right intercosto-bronchial trunk. Such vessels form a potential route for the passage of embolic material into the subclavian artery and its branches during therapeutic bronchial artery embolization. To avoid this potential complication, super selective catheterization with the positioning of the catheter tip well into the bronchial artery beyond the origin of the intercostal artery and any large collateral vessels is recommended.

Adult↗
PubMedDate not supplied

Evaluation and complications of direct graft puncture in thrombolysis and other interventional techniques.

PURPOSE: To evaluate the value and complications of direct graft puncture in conducting interventional procedures in synthetic vascular bypass grafts. METHODS: We retrospectively reviewed 65 direct graft punctures in 50 patients undergoing a variety of interventional vascular procedures. In two patients the grafts were found to be infected and the procedures abandoned. RESULTS: Complications encountered included hematomas that did not require treatment in three patients, and four hematomas requiring surgical drainage. One graft became infected (despite prophylactic cefuroxime), after three consecutive punctures over a 10-day period for a variety of interventions. All the patients who developed hematomas had undergone pharmacological thrombolysis. CONCLUSION: Direct graft puncture is a relatively safe technique, with a minimal risk of infection and hemostatic complications attributable to thrombolysis. In 31 of the 41 patients undergoing successful thrombolysis, additional percutaneous procedures were undertaken, and these were facilitated by the direct graft puncture route.

Aged↗
PubMedDate not supplied

The role of transradial diagnostic angiography.

PURPOSE: To evaluate the use of 4 Fr radial artery catheters as an alternative to both transbrachial and transfemoral approaches. METHODS: Seventy examinations were performed via the transradial route using 4 Fr 130-cm-long pigtail catheters. Prior to puncture the radial artery was assessed with pulse oximetry to ensure that it did not contribute the dominant blood supply to the hand. Patients were reassessed for complications within 24 hr of the procedure. RESULTS: Acceptable images were obtained in femoral arteriography, arch aortography, and selective carotid studies. In three of six renal arteriograms, images were suboptimal. There was a total technical failure rate of 5.7%. Significant complications were encountered in 4.3%, but no hand ischemia occurred. CONCLUSION: The transradial route for arteriography is easy to learn and has a low complication rate. It is a reasonable alternative approach to transfemoral arteriography for true outpatient peripheral angiography and in cases where the transfemoral route is not feasible, though it did not prove satisfactory for renal arteriography in hypertensive patients.

Adult↗