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Biomedical subjects

W C Lineaweaver

Publications and source records attributed to W C Lineaweaver.

At least 73 records · Page 4Linked to original sources
PubMed1996

Effect of anastomosis and geometry of vessel curvature on blood flow velocity and patency in microvessels.

The effect of the geometry of the vessel and the number of anastomoses on the blood flow was studied. Four different shapes of the vessel were constructed by using a 6-cm-long double vein graft model with three anastomoses: (1) an alpha loop, (2) an omega loop, (3) a sigmoid curve, and (4) straight. Blood flow was measured by an ultrasound Doppler flowmeter. The result showed no alternation in blood flow across different geometry and through three patent microanastomoses. However, six out of seven vein grafts were thrombosed at 24 hr postoperative due to vascular kinks. This model demonstrates potential sites of kinking at the dissection end of the femoral artery, the microanastomoses, the side branches of the vein graft, and the adventitial adhesions. This model is recommended to microvascular trainees for the study of kinking and the management of redundant pedicles and vein grafting.

Anastomosis, Surgical↗
PubMed1996

Effect of vein grafting on the survival of microvascularly transplanted muscle flaps.

Since vein grafting is often required during transplantation of free muscle flaps but is associated with a higher failure rate than those flaps transplanted with primary anastomoses, we sought to compare primary repair with the use of vein grafting in an experimental setting. We transplanted the gracilis muscle to the contralateral side in 98 rats using four different methods of vessel repair. In the Control group (n = 28), both femoral vessels were anastomosed primarily. In Experimental Group 1 (n = 25), the femoral artery was anastomosed with an epigastric vein graft and the femoral vein was anastomosed primarily. In Experimental Group 2 (n = 25), the femoral vein was anastomosed with a femoral vein graft and the femoral artery was anastomosed primarily. In Experimental Group 3 (n = 20), both femoral vessels were anastomosed with vein grafts. The Control and Experimental Groups 1-3 survival rates were 89.3, 76.0, 84.0, and 70.0%, respectively; none of the experimental group survival rates was significantly different from that of the control (P < 0.5). This study demonstrates that the use of size-matched, interpositional vein grafts in the arterial or venous pedicle of the rat gracilis muscle flap during transplantation did not significantly decrease flap survival as compared to primary arterial or venous anastomoses. If the observed failure rate persisted with expansion of the study groups to 60-100 animals each, the failure rate of flaps with vein grafts would be significantly lower and comparable to failure rates reported in some clinical series. The large numbers necessary to significantly show this decrease make this model impractical for further studies.

Anastomosis, Surgical↗
PubMed1996

Mechanical evaluation of anastomotic tension and patency in arteries.

This study quantified arterial anastomotic tension, evaluated subsequent patency rates, and examined the degree of tension reduction with vessel mobilization. The study was divided into two components. In part I, a mechanical analysis was undertaken to evaluate tension, based on the determination of the force required to deflect a cable (vessel) laterally, and its resulting lateral displacement. Six Sprague-Dawley rats with 12 femoral arteries were divided into two subgroups: 1) no mobilization; and 2) axial mobilization by ligation and transection of superficial epigastric and gracilis muscular branches. The tension of femoral arterial anastomoses was calculated in vessels with no segmental defect and with 1.5-, 3-, 4.5-, 6-, and 7.5-mm defects. In part II, patency was evaluated. Fifty-five rats with 110 femoral arteries were divided into two sub-groups as defined in part I: 1) no mobilization; and 2) axial mobilization by ligation and transection of superficial epigastric and gracilis muscular branches. Microvascular anastomoses were performed with no segmental defect and with 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, and 10-mm segmental vessel defects. Patency was evaluated 24 hr postoperatively. Part I of the study revealed that anastomotic tension gradually increased along with an increase in the length of the vessel defect, from 1.9 to 11.34 g in the no-mobilization group and from 1.97 to 8.44 g in the axial-mobilization group. Comparison of tension linear regression coefficient showed a significant difference between the two groups (p < 0.05). In part II of the study, the maximum length of femoral artery defects still able to maintain 100 percent patency of anastomoses was 4 mm (tension approximately 6 g) in the no-mobilization group and 6 mm in the axial-mobilization group (tension approximately 6.48 g). Microanastomotic tension was related to the size of the vessel defect, with increasing tension leading to thrombosis. Axial mobilization significantly reduced the tension in vessels with segmental defects and decreased thrombosis rates.

Anastomosis, Surgical↗
PubMed1996

Protection against ischemic-reperfusion injury of skeletal muscle: role of ischemic preconditioning and adenosine pretreatment.

Prolonged tissue ischemia and subsequent reperfusion result in significant tissue injury due to the ischemic-reperfusion syndrome. Although skeletal muscle has significant tolerance to ischemic-reperfusion injury (IRI), compared to other organ systems, IRI of skeletal muscle does occur when there is a prolonged ischemic period. In many reconstructive surgical procedures involving microsurgery and prolonged tissue ischemia time, IRI-induced skeletal-muscle injury is a serious clinical concern. Specifically, there are significant vascular complications (venous thrombosis and arteriolar no-reflow) and loss of transplanted muscle function on reperfusion with prolonged ischemia. Ischemic preconditioning (IPC) or adenosine (ADO) pretreatment applied prior to the ischemic period are known to protect against IRI in cardiac muscle. Recent data from basic science research suggest that IPC or ADO pretreatment may be employed to protect skeletal muscle against IRI. This review summarizes the basic mechanisms and potential clinical relevance of ischemia- and reperfusion-induced skeletal muscle injury and describes how skeletal muscle can be protected against IRI with IPC or ADO pretreatment.

Adenosine↗
PubMed1996

Gluteal infarction as a complication of aortofemoral bypass grafting.

Early complications following aortofemoral bypass grafting include acute limb ischemia, renal failure, bowel and spinal cord ischemia, and myocardial infarction. Although the literature recognizes these more common complications, we have found very few reports that raised the possibility of an anatomically determined, soft-tissue infarction as a complication of aortofemoral bypass grafting. Our plastic surgery service was consulted in August and October 1992 to examine 2 patients with soft-tissue complications following aortofemoral bypass grafting. Both patients were found to have complete gluteal infarction. Recognition of muscle infarction following aortofemoral grafting must be distinguished from postoperative pressure sores, since the muscle infarction requires prompt and thorough anatomic debridement to prevent in situ muscle liquefaction and sepsis.

Aged↗
PubMed1995

Experimental microvenous thrombosis following anastomosis with a knotted suture.

An experimental model for producing venous thrombosis was developed in end-to-end anastomoses of femoral veins in rats. The anastomoses were performed using a suture (9-0 suture-70 microns needle) with a knot 1 cm from the needle. The knot was formed by making either six or eight half-hitches in one throw of the suture. Vessel patency was assessed through the direct "milking test" at 20 min and 24 hrs. The incidence of thrombosis when using one knot with six half-hitches ranged from 20% to 40% and with eight half-hitches, from 50% to 70%. The incidence of femoral vein thrombosis varied directly with the presence and size of the knot. In this model, thrombosis was induced by exaggerating vessel injuries that may occur when performing routine microvascular anastomoses. This study demonstrates a reproducible thrombogenic model which mimics clinical practice and may be used to study the effects of local and systemic antithrombogenic agents.

Anastomosis, Surgical↗
PubMed1995

Microvenous thrombosis rates following anastomosis with vein grafting and a knotted suture.

An experimental microvenous thrombosis model was developed combining vein grafting in femoral vein defects with exaggerated vessel injuries using a knotted suture in the vessel repair. The rat femoral vein grafts were separately subjected to injuries caused by an anastomosis performed with a suture knotted with eight half-hitches at the distal anastomosis (upstream), the proximal anastomosis (downstream), and both anastomotic sites. These groups were compared to vein grafting done with a standard suture. Vessel patency was assessed at 20 min and 24 hr, and the thrombus component was histologically analyzed at 24 hr after the procedures. One hundred percent of control vein grafts were patent at 24 hr. All experimental groups had significantly decreased patency at 24 hr (P < 0.001). Among the experimental groups, knotted suture anastomoses at both anastomoses produced significantly lower patency (13.3%, P < 0.05) than knotted suture anastomoses at distal anastomoses. Histological analyses of thrombosed grafts showed that a large amount of thrombocyte deposition and inflammatory cells were noted at both anastomotic sites in the vein grafts with a knotted suture at the distal anastomosis and in the grafts with a knotted suture at both anastomoses. Thrombocyte deposition and inflammatory cells were seen only at the site of proximal anastomosis when using a knotted suture at the proximal anastomosis site alone. This study demonstrated that quantified microvenous thrombosis can be produced by exaggerating vessel injuries with a knotted suture in a vein graft model. This thrombosis model can be used to study the effects of antithrombogenic agents.

Anastomosis, Surgical↗
PubMed1995

Comparison of nylon and polypropylene sutures in a microvenous thrombosis model.

Thrombosis rates of femoral end-to-end microvenous anastomoses with nylon and polypropylene sutures (9-0 suture, 70 mu needle) were compared in a microvenous thrombosis model. The vessel injuries were produced during anastomosis by using a suture with a knot 1 cm from the needle. Anastomotic thrombosis rates were assessed by visual inspection and strip test at 24 hr postoperatively. Low thrombosis rates (0% and 20%, respectively) of anastomoses with both unknotted nylon and unknotted polypropylene sutures were obtained. Anastomoses with knotted nylon and polypropylene sutures resulted in 65% and 45% thrombosis rates, respectively. Statistical analyses showed that there were no significant differences between thrombosis rates, both in anastomosis performance with unknotted nylon and polypropylene sutures (P > 0.05) and with knotted nylon and polypropylene sutures (P > 0.05), while there were significant differences between the thrombosis rate using unknotted sutures and knotted sutures (P < 0.01). It was concluded that vascular injury, not suture material, is the main factor leading to thrombosis in this model.

Anastomosis, Surgical↗
PubMed1995

Lemierre's syndrome: a case of postanginal septicemia and bilateral flank abscesses.

Lemierre's syndrome is characterized by pharyngeal infections in young healthy adults with secondary septic thrombophlebitis and multiple metastatic infections. In the preantibiotic era, Lemierre's syndrome was common and lethal. With the advent of antibiotics, Lemierre's syndrome has become such a rare entity that the diagnosis is often delayed or missed. With prompt recognition, appropriate antibiotic therapy, and surgical drainage of metastatic abscesses, the majority of patients can be cured. A case of Lemierre's syndrome in a 22-year-old previously healthy man treated on a plastic surgery service is presented. Surgeons who can be consulted for deep space infections should be aware of this disease so that the diagnosis and treatment can be initiated promptly to prevent patients from succumbing to this life-threatening but curable disease.

Abscess↗
PubMed1994

The greater omentum transplantation model in the rat.

Dissection of the rat omentum were performed to study the feasibility of rat omental free transfer. The right epiploic vessels were found to be adequate for anastomosis in transfer. Twelve omental free flaps were transferred to the groin, with 100% survival of flaps in the 10 animals that survived the operation. The artery and vein averaged 0.3 and 0.4 mm in diameter, respectively. The average pedicle length was 5 mm, and the average flap weight was 136.9 mg. This omental transplant offers a new experimental means of studying lymphedema, neovascularization, and tissue revascularization.

Animals↗
PubMed1994

Pectoralis major muscle free flap in rat model.

The rat pectoralis muscle can serve as a vascularized, innervated muscle flap model. The muscle, consisting of superficialis and profundus portions, is supplied by separate neurovascular systems. The vessels to pectoralis profundus (averaging 0.3 mm in diameter) can be taken in continuity with the axillary vessels (averaging 11 mm in diameter), which are used for transplantation. The profundus portion of muscle weighed an average of 1.8 g, and the average pedicle length was 0.9 cm. Nine of 11 transplanted muscles were viable, with intact circulation at 72 hours. An example of muscle transplantation for tissue defect coverage was attempted. The pectoralis profundus transplant was technically reliable, and the muscle bulk and contour could allow biochemical and functional studies.

Abdominal Muscles↗
PubMed1994

Primary common bile duct anastomosis in the rat using microsurgical techniques.

In a rat model, we attempted to describe the natural healing course of the common bile duct (CBD) after primary microsurgical repair. Fifty-three rats were divided into experimental groups with CBD microsurgical anastomoses and control groups with CBD mobilization and ligation. Examination of three experimental groups at 1 week, 1 month, and 3 months showed evolving inflammation and stricture changes with eventual patent, healed ducts in 92% of animals at the end of 3 months following transection and repair. There were no histologic abnormalities in the livers. There were fibrotic ducts and hepatic stasis and cirrhosis changes in the control group with CBD ligation. This study demonstrates that microsurgical techniques can achieve successful primary biliary repair in the rat.

Anastomosis, Surgical↗
PubMed1994

Sensory reinnervation of muscle free flaps for foot reconstruction.

A retrospective study was performed to measure sensibility in sensory-to-motor innervated microvascular muscle transplants to the foot. Seven transplants were on the weight-bearing surface of the foot. Five of seven flaps had light-touch sensation. Mean vibrometer readings of the innervated transplants were 15.7 (range: 5 to 40) vs. 5.3 (range 2 to 9) on the contralateral foot. Semmes-Weinstein scores of the innervated flaps were 3.84 (one), 4.74 (one), 5.46 (two), and 6.45 (three) vs. 3.22 (one), 3.84 (one), 4.08 (one), and 4.17 (four) on the contralateral foot. This study documents that sensory-to-motor innervated free muscle flaps may regain measurable sensibility.

Adult↗
PubMed1994

Intestinal flora of the medicinal leech Hirudinaria manillensis.

Medicinal leeches are widely used to treat venous congestion in microvascular surgery. Aeromonas hydrophila infection, following application of the leech species Hirudo medicinalis, is a recognized complication. Administration of antibiotics directed at Aeromonas has been successful in minimizing complications of infection from this organism. A different leech species, Hirudinaria manillensis, has recently been introduced for microsurgical use. A study of the enteric content of 30 of these leeches showed that Aeromonas hydrophila was isolated in only 20 percent of animals, while the majority of remaining positive cultures were single and mixed gram-negative rods. All organisms isolated were sensitive to current recommended coverage for Aeromonas hydrophila. This study suggests that the enteric flora of different leech species may be variable and should be carefully characterized, to direct appropriate prophylactic therapy prior to release of new species for clinical use.

Aeromonas↗
PubMed1994

Microvascular muscle and myocutaneous transplantation models in the rat.

Rat cutaneous free-flap models have received widespread attention, but muscle and myocutaneous free-flap models in the rat are relatively unknown. These latter models are reliable, reproducible, and economical. Survival of the transplanted tissue is dependent on the axial blood supply, with an all-or-none survival pattern. This article is a summary of the anatomy, transplantation characteristics, and potential application of these muscle and myocutaneous free-flap models in the rat.

Animals↗