Eficácia da redilatação coronária em portadores de reestenose da artéria descendente anterior / Efficacy of repeat percutaneous transluminal coronary angioplasty for coronary restenosis of the proximal left anterior descending coronary artery

PURPOSE: To analyze the clinical characteristics, acute and long term results of repeat percutaneous transluminal coronary angioplasty (PTCA) for restenosis of the proximal left anterior descending coronary artery (LDA) METHODS: We studied 113 patients, 79 male, mean age 59 years, 49.5 had stable angina, with single vessel proximal LDA disease undergoing repeat PTCA for a first restenosis from January/88 to December/92. We examined the in hospital outcome (success rate and complications) and long term follow up (angina status, occurrence of myocardial infarction (MI), death and need for repeat PTCA or coronary artery bypass graft (CABG) of this subgroup. RESULTS: Primary success was 96. Complications included: 1 MI, 1 emergency CABG and 1 procedural death. Follow up data (mean 42 months) was available in 102 (94) out of 109 patients with successful repeat PTCA: 64 (63) patients were asymptomatic, 5 (5) had a MI and 28 (27) required repeat PTCA or CABG. Actuarial 5 year freedom from death was 94, freedom from death and MI was 91 and freedom from death, MI and repeat PTCA or CABG was 52. CONCLUSION: Repeat PTCA is an effective treatment for proximal LAD restenosis with a high success rate, low incidence of procedural complications and provides excellent long term cardiac survival, however repeat revascularization is frequently required.

Objetivo - Analisar as características clínicas e angiográficas, e a evolução hospitalar e tardia dos pacientes submetidos à redilatação pós-reestenose da artéria coronária descendente anterior (DA). Métodos - Cento e treze pacientes uniarteriais, sendo 89 (79%) homens, com média de idade de 59 anos, 49,5% com quadro de angina estável, foram submetidos a angioplastia coronária eletiva da DA e redilatados no período de janeiro/88 a dezembro/92. Foram analisados quanto à evolução hospitalar (sucesso e complicações) e tardia (ocorrência de infarto agudo do miocárdio (IAM), óbito e necessidade de novos procedimentos de revascularização - NPR). Resultados - O sucesso primário foi de 96%, ocorrendo 1% de JAM, 1% de cirurgia de emergência (CE) e 1% de óbito. Foram seguidos 102 (94%) pacientes, em média por 42 meses, sendo que 63% estavam assintomáticos, 5% apresentaram IAM, 5% morreram e 27% necessitaram NPR (aterectomia ou cirurgia). As curvas actuariais de 5 anos revelaram 94% de sobrevida global, 91% de sobrevida livre de IAM e 52% de sobrevida livre de IAM e NPR. Conclusão -A redilatação coronária pós-reestenose da DA é procedimento seguro e eficaz. As curvas actuariais revelaram excelente prognóstico, embora NPR sejam freqüentes

The effects of implant orientation, canal fill, and implant fit on femoral strain patterns and implant stability during catastrophic testing of a canine cementless femoral prosthesis.

Cementless femoral stems were placed into 12 normal greyhound femora. The implanted femora were divided into three groups by stem orientation and implant size and loaded in axial compression at a rate of 25 newtons (N) per second until failure. Rosette strain gauges were used to measure femoral principal strains at 500 N, 1,000 N, 1,500 N, and at maximum load. During maximum load, varus orientation of the femoral stem had significantly higher tensile hoop strains in the proximomedial cortex, whereas neutral orientation had higher tensile hoop strains along the cranial cortex. Femoral fractures occurred in these areas of peak tensile strain. There was no difference in maximum load between groups, therefore varus orientation did not predispose to fracture. Maximizing canal fill and implant fit increased implant stability.

The intercondylar fossa of the normal canine stifle an anatomic and radiographic study.

The intercondylar fossa (ICF) in dogs consists of a cranial outlet, intercondylar shelf, caudal arch, caudal outlet, a medial wall, and a lateral wall. The normal cranial outlet is bell-shape and, in mixed-breed dogs (mean body weight 19.2 kg, N = 21), measured 5.8 mm cranially, 8.1 mm centrally, and 10.3 mm caudally. The ICF is oriented 12 degrees from the dorsal plane of the femoral diaphysis and obliqued 7 degrees, proximolateral to distomedial, in the sagittal plane. To adjust for dog size, a fossa width index (FWI) was calculated by dividing the cranial outlet width by the distance between epicondyles. The normal FWI as determined in this study was 0.18 cranially, 0.25 centrally, and 0.32 caudally. The fossa height index 0.31. Contact between the ICF and the cranial cruciate ligament began at about 115 degrees of extension. The contact area moved cranially in the intercondylar fossa as the stifle was extended. Evaluation of the ICF can be performed radiographically but positioning is critical.

The effect of intercondylar notchplasty on the normal canine stifle.

This study evaluated the effect of notchplasty (enlargement of the intercondylar fossa) in stable and unstable canine stifles. Bilateral notchplasty and unilateral cranial cruciate ligament (CrCL) transection were performed in 6 dogs. Exercise, consisting of walking 1.5 miles three times a week, began 1 month after surgery and continued until euthanasia 6 months after surgery. Evaluation methods included orthopedic examination, serial radiographs, thin section radiography, histopathology, and gross pathology. Notchplasty in the stable stifle did not cause lameness beyond 3 weeks, joint instability, or degenerative joint disease. In the stable stifle, smooth resurfacing of the notchplasty site with fibrous and osseous tissue occurred. Stifles with notchplasty and CrCL transection exhibited persistent lameness, instability, and degenerative joint disease. In CrCL deficient stifles osteophytes formed within the notchplasty site, resulting in a rough surface. Our observations indicated significant refilling in notchplasties of both stable and unstable stifles (P < .05). However, the intercondylar fossa (ICF) width 6 months after notchplasty was significantly smaller in unstable stifles compared with stable stifles (P < .05) indicating that greater refilling of the notchplasties occurred in the unstable stifles. In clinical cases, notchplasty should be larger than the desired final result to accomodate the partial refilling that occurs even in stable stifles.

Femoral strain distribution and subsidence after physiological loading of a cementless canine femoral prosthesis: the effects of implant orientation, canal fill, and implant fit.

Twelve normal greyhound femora were divided into three groups. In group one, femoral stems were placed in neutral position with maximal fill. Group two had undersized femoral stems placed in neutral position. Group three had undersized femoral stems placed in varus position. Intact and implanted femora were loaded from 10 newtons (N) to 300 N in axial compression at a rate of 25 N/s for 10 replications. A strain gauge analysis showed that the strain distribution of all implanted femora were substantially different from intact femora, but femora with large implants placed in neutral position had the least amount of deviation from normal. An undersized stem in neutral position had significantly less compressive longitudinal strains along the proximomedial and proximocranial cortices. An undersized stem in varus position improved implant fit along the proximomedial and distolateral cortices, which resulted in increased tensile hoop strains. There were multiple significant correlations between the strain data and implantation variables (implant alignment, canal fill, and implant fit). Subsidence was significantly greater for the undersized implant in neutral position. There was not a difference in subsidence between the large neutral and varus groups. The most important variable that decreased subsidence was increased lateral implant fit (r = -0.86, P = .0003).

Total hip arthroplasty for treatment of canine hip dysplasia.

Cemented THA is an established procedure for treating arthropathies of the hip in large, healthy mature dogs. CHD with secondary osteoarthritis is the most common indication. Although comparative studies between THA and excision arthroplasty have not been reported, our experience with both procedures and studies in the literature support THA as the best available treatment for crippling degenerative joint disease secondary to CHD in large, mature dogs. Negative aspects of the procedure include high cost, the potential of significant complications, and the sophisticated surgical technique required. Improvements in patient selection, design of implants, surgical technique, and postoperative care have decreased the incidence of complications and improved the success rate to over 90%. However, concerns in human applications about cement disease and the desire to increase the functional life of the prosthesis have renewed interest in cementless systems. Advantages of cementless THA are fixation via bony ingrowth and avoidance of problems associated with PMMA. Important technical aspects of cementless THA relate to optimal fit and fill so that the prosthesis is stable, bone ingrowth is promoted, and weight-bearing forces are transferred to the proximal femur physiologically. Problems recognized with cementless systems include fissure fracture, bone resorption, and excessive motion between the implant and bone. Currently, investigations are being conducted to develop prosthetic materials that more closely match the stiffness of bone, stem designs that provide optimal fit and maintain normal strain patterns in the bone, and coating materials that promote permanent fixation by bone ingrowth. Early clinical results in humans and research results in dogs have been encouraging but have not withstood the test of time. Results of cementless techniques must be compared to the standards set by cemented THA over the last 20 years in humans and the last 10 years in dogs.

Hip dysplasia with bilateral ischiatic nerve entrapment in a dog.

Dysfunction of both ischiatic nerves was detected in a 5-year-old spayed Labrador Retriever with radiographic evidence of severe bilateral hip dysplasia. Marked hyperflexion of the hip and stifle was evident when the dog walked. Results of electromyography confirmed the ischiatic nerve involvement. At staged operations, both ischiatic nerves were found to be compressed between the sacrotuberous ligament and proliferative tissue around the hip. One year after surgery, electromyographic and physical findings were essentially normal.

Comparison of aerobic culturette, synovial membrane biopsy, and blood culture medium in detection of canine bacterial arthritis.

Canine joints were cultured 24 hours after inoculation with Staphylococcus intermedius using synovial membrane biopsy, synovial fluid on aerobic culturette and in blood culture medium, and synovial fluid incubated 24 hours in blood culture medium before being cultured. A mildly virulent strain consistently yielded positive cultures when incubated in blood culture medium 24 hours and negative cultures with the other techniques. A highly virulent strain also yielded positive cultures when incubated in blood culture medium 24 hours, which was significantly better than synovial membrane biopsy. When both strains were considered together there was no significant difference between the first three techniques; blood culture medium incubated 24 hours was significantly more reliable. These results suggest that the trauma of synovial membrane biopsy is not justified because synovial fluid culture is more reliable. Synovial fluid should be placed on an aerobic culturette and in blood culture medium, and the samples cultured immediately upon arrival at the laboratory to allow the most rapid results of culture and antibiotic sensitivity testing. The blood culture medium should be recultured after 24 hours of incubation to permit culture and antibiotic sensitivity testing of those samples (approximately 50%) that have no growth on initial culture.

Elevation of thromboxane in pressure wounds.

Arachidonic acid metabolites have been implicated as mediators of progressive dermal ischemia. Decubitus ulcer formation results from chronic mechanical pressure on the skin which results in a diminished blood supply to the skin and underlying tissues. To evaluate the role of thromboxanes in pressure wounds, we measured TxB2, a stable metabolite of TxA2, in spontaneously occurring pressure wounds on Greyhound dogs. In pressure wounds in which the skin was showing early signs of pressure necrosis but was still intact, elevated TxB2 concentrations were found in healthy appearing tissues immediately adjacent to the pressure wounds, in the inner edge of the wounds, and in the center of the wounds. Significantly greater TxB2 concentrations (P less than 0.05) were found in the center of the intact wounds versus the TxB2 concentrations in the inner edge of the wounds or in healthy appearing tissues adjacent to the wounds. In pressure wounds in which the center of the wound had ulcerated or had an eschar, elevated TxB2 concentrations were found in tissues in the inner edge of the wounds and in healthy appearing tissues immediately adjacent to the pressure wounds. These results demonstrate the occurrence of elevated thromboxane concentrations in and around spontaneously occurring pressure wounds.

Comparison of over-the-top and tunnel techniques for anterior cruciate ligament replacement.

The osseous tunnel technique of anterior cruciate ligament (ACL) reconstruction was compared to the over-the-top (OTT) technique in vivo. A prosthesis replaced the ACL in 35 dogs by one of three methods: double osseous tunnels, OTT, or a combined method utilizing the unique Y shape of the prosthesis by placing one fork through a femoral osseous tunnel and the other fork over the top of the femoral condyle in the same stifle. Rupture occurred in all prostheses placed in double osseous tunnels and in one of 12 prostheses placed by the OTT technique. When rupture occurred in only one fork of prostheses placed in the combined method, all occurred in the tunnel-placed fork. If the results of the three groups are combined, rupture occurred in 16.7% of all OTT-placed prostheses versus 91.3% rupture of all osseous tunnel-placed prostheses. Objective assessment of the in vivo testing clearly indicates that the OTT technique is superior to the tunnel technique under the conditions of this study. The relationship between placement technique and rupture of other prostheses should also be tested in vivo.

A retrospective comparison of three techniques for femoral head and neck excision in dogs.

Femoral head and neck excision was performed in 169 dogs over a 7 year period. A written questionnaire completed by 56 owners, evaluating a total of 72 joints, was the basis for retrospective evaluation of the efficacy of the procedures used. There were four surgical groups: femoral head and neck excision (FHNE) in dogs with body weights over 14 kg, the same procedure in dogs with body weights less than 14 kg (SMALL), femoral head and neck excision with muscle interposition (MI), and the wedge resection technique (WRT). Although differences in results were noted, there were no statistically significant differences between any of the groups for the percentage of leg use during normal activity (p greater than 0.05), mean postoperative time until leg use, use of the leg or hopping while running, or lameness with exercise (p greater than 0.10). The results of this study suggest that there is little advantage in performing the more time-consuming and traumatic muscle interposition and wedge resection procedures.

Congenital elbow dislocations.

Three categories of congenital elbow dislocations are described in the literature: humeroulnar, humeroradial, and dislocation or joint laxity with other congenital anomalies. Congenital humeroulnar dislocation is a well-defined problem that occurs predominantly in small breeds of dogs and causes severe limb deformity and dysfunction. Early reduction and stabilization are simple to achieve and have provided good results. Radial head dislocations occur most often as a result of growth disturbance of the radius and ulna. There is a lack of conclusive information on congenital radial head dislocations. Regardless of the etiology, radial head dislocation causes rather mild deformity and lameness and can be treated by conservative management, surgical correction, or radial head ostectomy. Dislocation of the elbow may occur concurrently with other rare congenital anomalies and has been described with ectrodactyly and polyarthrodysplasia.

Plasma concentrations of chloramphenicol in snakes.

Plasma chloramphenicol concentrations after a subcutaneous injection were studied in 87 snakes of 16 different species. The biological half-life of chloramphenicol varied from 3.3 hours in the indigo snake (Drymarchon corais couperi) to 22.1 hours in the midland water snake (Nerodia sipedon). A single dosage of 50 mg of chloramphenicol/kg of body weight produced plasma concentrations greater than 5 micrograms/ml for nearly 72 hours in 2 species of water snakes (Nerodia erythrogaster, Nerodia sipedon), for 24 hours in the Burmese python (Python molurus bivittatus), and for less than 12 hours in the gray rat snake, Indigo snake, and eastern king snake (Elaphe obsoleta spiloides, Drymarchon coraise couperi, and Lampropeltis getulus getulus). A dosage of 50 mg/kg administered to water snakes every 72 hours for 18 days maintained a minimum plasma concentration of chloramphenicol between 2 and 5 micrograms/ml.

Closed reduction and blind cross-pinning for repair of a proximal tibial fracture in a foal.

A 4-day-old foal underwent repair of a proximal metaphyseal fracture of the tibia. After closed reduction, fixation was achieved by use of blind cross-pinning. Thirty-five days after surgery, radiography demonstrated complete healing. The foal was mildly lame 4 months after repair of the fracture. Blind cross-pinning may be considered as a method of repair for certain long bone fractures in small foals.

Plasma concentrations of chloramphenicol in birds.

The plasma concentrations of chloramphenicol after oral, IM, and IV administrations were studied in 15 species of birds. The biological half-lives of chloramphenicol ranged from 26 minutes in the pigeon, Columbia livia, to 288.3 minutes in the bald eagle, Haliaeetus leucocephalus. In those birds studied, the oral route gave low and inconsistent plasma chloramphenicol concentrations. The IM route was the most satisfactory. Based on the data presented, an IM dose of 50 mg/kg would produce plasma concentrations above 1 micrograms/ml for 8 to 12 hours, except in the pigeon, macaw, conure.

Effect of localized trauma and temporary splinting on immature skeletal muscle and mobility of the femorotibial joint in the dog.

The right pelvic limbs of 2 groups of dogs were splinted in extension for 2 weeks. In 1 of these groups, the dogs were anesthetized and the distal portion of the quadriceps femoris muscle was traumatized before splinting. Two groups of control dogs were also used; neither group was splinted, but 1 group was anesthetized, and their muscles were traumatized. The range of motion of the femorotibial joint was measured in all 4 groups before splinting and 3 and 9 weeks after splinting. Types I and II muscle fiber diameters and percentages were also recorded at 3 and 9 weeks in all groups. Flexion of the femorotibial joint was limited after splinting (P less than 0.001), but less so after trauma and splinting than after splinting alone (P less than 0.0001). A reversible type I fiber atrophy occurred in most restricted muscles (P less than 0.001) and early type II fiber atrophy was seen in a few muscles after trauma and splinting (P less than 0.002). Multifocal fiber necrosis was the only irreversible change seen after 3 weeks of splinting with or without concurrent muscle trauma. Relative fiber percentages did not change appreciably during splinting or recovery.