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Biomedical subjects

A C Meek

Publications and source records attributed to A C Meek.

13 recordsLinked to original sources
PubMed1997

Artery wall damage and platelet uptake from so-called atraumatic arterial clamps: an experimental study.

A 'traumatic' clamps are routinely used to control arteries during reconstruction, but little is known about the arterial damage caused and the effects on platelet uptake. This experiment used sheep carotid arteries to correlate the degree of histologic damage observed with the level of indium-111-labelled platelet uptake in clamped arterial segments. Scanning electron microscopy and light microscopy enabled three degrees of injury to be recognized. In mild injuries, endothelial cell orientation was changed but local platelet uptake was little different from controls. In moderate injuries, the endothelial cells directly squeezed by the clamp were morphologically altered, superficial fissures developed which extended into the media, and local platelet uptake was usually increased. Severe injuries caused extensive endothelial cell desquamation, formation of deep cavities in the media and increased platelet uptake (mean 5.51 times that of control). Platelet uptake at the site of clamp application was not significantly different from non-clamped carotids for mild injuries. However, the increased platelet uptakes for moderate (P = 0.007) and severe (P = 0.005) injuries were statistically significant when compared with non-clamped control arterial segments.

Animals↗
PubMed1996

Acute platelet deposition after carotid endarterectomy in sheep: vein patch compared with gelatin-sealed Dacron and polytetrafluoroethylene patch closure.

PURPOSE: Patch angioplasty is commonly used to close the arteriotomy after carotid endarterectomy is performed. The purpose of this study was to determine whether any significant variations were present in platelet deposition for different patch sizes and materials. METHOD: The study measured 111-indium-labeled uptake in the sheep to compare thrombus deposition for three different patch materials: autologous vein, gelatin-sealed Dacron, and polytetrafluoroethylene and for 6- and 12-mm patch widths. Platelet uptake was measured on the patch itself and on the artery wall that was opposite to the patch and that had undergone endarterectomy. Scanning electron microscopy was used to confirm the localization of the labeled platelets on the patch and on the surface that had undergone endarterectomy. RESULTS: Although considerable variation was seen among animals, platelet accumulation was lowest in the vein patches compared with the prosthetic patches (p < 0.01), but the deposition on the gelatine-sealed Dacron was not significantly different from that on polytetrafluoroethylene patches. Platelet deposition on the artery wall that had undergone endarterectomy was considerably less than on the patch but was higher when a synthetic patch was used rather than a vein patch (p < 0.05). CONCLUSIONS: Acute thrombus deposition after carotid endarterectomy was considerably less for vein patch closure than for synthetic patches. A 6-mm patch width caused less thrombus deposition both on the patch itself and on the artery wall compared with a 12-mm patch, but the difference was proportional to the patch width.

Animals↗
PubMed1995

Carotid-subclavian bypass and the carotid steal phenomenon.

Twelve patients with patent carotid-subclavian bypass grafts were investigated by colour flow duplex imaging to look for a carotid steal. Centre-stream peak systolic flow velocities in the common carotid arteries distal to the take-off of the bypass graft were equivalent to those in the contralateral common carotid artery. On the side of the bypass, common carotid flow proximal to the graft was almost double that on the distal side. Steal phenomena were not identified in the carotid artery either with the arm at rest or during hyperaemia. However, in two instances arm hyperaemia caused reversal of flow in the ipsilateral vertebral artery, suggesting the induction of a subclavian steal. The method of centre-stream peak systolic velocity as an index of flow confirmed that carotid-subclavian bypass can be safely carried out without depriving the cerebral circulation of the normal carotid inflow.

Aged↗
PubMed1994

Vascular surgery.

Explore the source record for details and available documents.

Angioplasty, Balloon↗
PubMed1994

Transverse abdominal incisions compared with midline incisions for elective infrarenal aortic reconstruction: predisposition to incisional hernia in patients with increased intraoperative blood loss.

PURPOSE: Both midline and transverse abdominal incisions are used for exposing the infrarenal aorta. Transverse incisions are said to cause less pulmonary and systemic complications, but the claimed advantages may be because most transverse incisions are extraperitoneal, whereas midline incisions are intraperitoneal. This study compares intraperitoneal transverse and midline incisions with respect to perioperative and late complications, especially incisional hernia. METHODS: Three hundred twenty-nine patients undergoing infrarenal aortic reconstruction (239 aneurysms; 90 occlusive disease) were analyzed retrospectively according to whether the abdominal wall incision was midline (154 patients) or transverse (175 patients). In all patients, the subsequent dissection was transperitoneal and not retroperitoneal. RESULTS: Perioperative survival rates and intraoperative blood loss were comparable, but the transverse incision tended to be followed by a shorter period of postoperative ileus (p = 0.07), perhaps because the small bowel was not always exteriorized during operation with transverse incisions. Mean time spent in the intensive care unit was not different between the groups, but those with transverse incisions remained in hospital 5 days less than those receiving midline incisions (p = 0.0005). When an aortic graft greater than 18 mm in diameter was used, survival was reduced compared with that after smaller grafts (p = 0.028). At 1 to 6 years follow-up in 235 patients (109 midline; 126 transverse), 35 (14.9%) incisional hernias were detected, with no statistical difference according to incision (16.5% midline; 13.4% transverse). Analysis by univariate and multivariate logistic regression showed that blood loss at operation exceeding 1000 ml increased the risk of later incisional hernia by a factor of 3.07. Wound infection increased the risk of hernia by 3.70. CONCLUSION: Excess blood loss and wound infection exerted this predisposition to incisional herniation independent of other variables.

Aged↗
PubMed1990

Gallbladder emptying following cholecystokinin and fatty meal in normal subjects.

A quantitative study of gallbladder emptying using 99mTc-HIDA as a bile tracer was performed with either CCK or a fatty meal as gallbladder stimulant. Its aims were to establish; (1) the reproducibility of CCK- and fatty-meal-induced gallbladder contraction, and (2) temporal patterns of gallbladder emptying following a physiological meal. Nineteen healthy, fasted volunteers were selected for 3-minute CCK administration (IV Boots Pancreozymin 2CHR units/kg) or a 40 g fatty meal. Each underwent repeat scans not less than 14 days after the first. Quantitative activity/time curves were drawn with computer analysis establishing gallbladder ejection fractions (GBEF) for each stimulus. Our results demonstrated: (1) poor reproducibility of CCK-induced gallbladder contraction precluding its diagnostic use, (2) improved but still variable meal-induced gallbladder contraction, and (3) evidence for a neurocephalic emptying response with a fatty meal stimulus.

Adult↗
PubMed1988

Platelet kinetics following carotid endarterectomy: the effect of aspirin and patch angioplasty.

Platelet deposition on the subintimal surface of the arterial wall following endarterectomy has been implicated in the development of postoperative thrombosis, intimal hyperplasia and may be important in recurrent stenosis. Autologous radiolabelled platelet deposition has been measured in 51 patients following carotid endarterectomy. The effect of platelet inhibitory drugs and patch angioplasty on early postoperative platelet accumulation at the site of endarterectomy has been investigated. In patients undergoing direct suture of the arteriotomy, platelet deposition measured as the Carotid Uptake Ratio was significantly reduced from 1.44 +/- 0.03 to 1.11 +/- 0.35 in those receiving aspirin and dipyridamole (P less than 0.002). Carotid Uptake Ratio was greater following patch angioplasty at 1.41 +/- 0.07 when compared to 1.14 +/- 0.07 with direct suture of the arteriotomy (P less than 0.002).

Aspirin↗
PubMed1986

Effect of the cyclo-oxygenase inhibitor indobufen on platelet accumulation in prosthetic vascular grafts.

An in vivo method of measuring thrombus deposition and pseudo-intimal thickening in prosthetic arterial grafts in an animal model is described. The effect of indobufen, a new cyclo-oxygenase inhibitor, was evaluated and compared to aspirin plus dipyridamole and placebo in 24 greyhounds. Luminal platelet accumulation expressed as thrombogenicity index was 0.33 +/- 0.07 in the placebo group. This was significantly reduced to 0.14 +/- 0.01 by indobufen (P less than 0.05). The reduction to 0.19 +/- 0.04 by aspirin plus dipyridamole failed to achieve statistical significance. Pseudointimal thickness when measured 28 days after implacement was significantly reduced to 21.4 +/- 10.6 per cent by indobufen (P less than 0.01) and 29.4 +/- 10.6 per cent by aspirin plus dipyridamole (P less than 0.02) compared to 75 +/- 10 per cent found in the placebo group. This prosthetic graft model has considerable advantages in the evaluation of potential platelet inhibitory drugs for use in vascular surgery.

Animals↗
PubMed1984

Vascular injury with associated bone and joint trauma.

The clinical presentation and management of 102 vascular injuries associated with bone and joint trauma, in 100 patients over a 6-year period, is reviewed. Eighty-three injuries involved the lower limbs. Amputation became necessary in 16 patients. In 12 this was directly attributable to delay in revascularization or the extent of the soft tissue injury with consequent sepsis. Early graft occlusion in an otherwise salvageable limb occurred in four patients (3.9 per cent). Successful therapy involves close co-operation between vascular and orthopaedic surgeons with the vascular injury taking priority. The orthopaedic injury should be treated on its merits. In contaminated or comminuted fractures skeletal traction (or in suitable cases exoskeletal fixation) can be employed without adversely affecting the vascular repair. A plea is made for early diagnosis of concomitant vascular injury in patients with bone and joint injuries; this depends on clinical awareness and careful and repeated examination.

Adolescent↗