Biomedical subjects
Publications and source records attributed to J M Chevalier.
Femoro-popliteal bypass is difficult to perform when the posterior tibial artery originates at a high level in the lower limb. The problems arising from this anatomical variation, in which the tibio-peroneal trunk is, at least classically, anterior to the popliteal muscle, can be overcome by the technique described.
The laser used in this study (NEURALASE R1) is a light-emitting diode which emits continuous or modulated impulsional signals in the near infra-red (approximately 850 nm). The power emitted varies between 1 and 11 mW. The instrument is placed at a fixed distance from a photovoltaic sensor whose voltage response is a linear function of the received luminous power. The voltage variations are studied as functions of the thickness of the compact bone interposed between the output of the laser and the diode. On semilogarithmic paper, we find a curve of two linear segments having different slopes. The first (between 0 and 1 mm of bone), of very sharp incline, is most probably due to an important reflexion on the bone surface; the second, with a slight incline, corresponds to the absorption which is exponential. Moreover, if the ray enters in the cortico-medullar direction, the second slope is sharper than in the case of a longitudinal penetration following the diaphyseal texture. A power of 10 mW gives a maximal penetration of about 18 mm in the bone axis direction and approximately 6 mm in the cortico-medullar direction. For eventual therapeutic indications, it is necessary to take account of reflexion on the bone surface as well as the direction of the beam in relation to the bone texture, since these two elements interfere in the diffusion of the stimulation.
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A comparative study was conducted on three micrografts of 2 mm diameter: a frozen umbilical artery, a bovine heterograft and an inert P.T.F.E. material graft. These were implanted in the infrarenal aorta of 158 Wistar rats. Each graft was examined on eight occasions: after 4, 24 and 48 hours, one and two weeks, and 1, 2 and 6 months. Excluding 46 animals that died within 24 hours, the overall permeability rate for all grafts was 87.7% (88.9% for umbilical arteries, 82.8% for bovine heterografts and 85.4% for P.T.F.E.). All grafts were examined by optical and electron microscopy. The inert material showed excellent parietal stability. In contrast, alteration and resorption of the primary matrix were moderate in extent for bovine heterografts, and major for frozen umbilical arteries which appear to be a very unstable grafts.
A rarely reported method for revascularization of lower limbs is the use of descending thoracic aorta and a prosthesis passing through the subpleural and subperitoneal tissues. It is nevertheless a valuable procedure in patients in good general condition in whom there is a local contraindication to the abdominal approach. It appears to be more reliable in the long term than a conventional axillofemoral shunt.
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The authors report 2 cases, in which recurrent and reversible atelectasis of the left lung was the only manifestation leading to a diagnosis of post-traumatic aneurysm of the thoracic aorta at an early stage (D + 5). Other classically described signs were absent. These 2 cases demonstrate the need to seek an aortic aneurysm following any severe trauma. They emphasize the importance of bronchial endoscopy in this type of trauma. They confirm the value of CAT scan investigation.
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A rare case of thrombosis of the popliteal artery due to an exostosis of upper end of tibia is reported. It is rare for exostoses to develop at the upper metaphysial region of the tibia, rare fore vascular complications to develop and particularly rare for these to consist of thromboses. This lesion is a differential diagnosis in young adults with lower limb ischemia. Follow up of these exostoses should be by Doppler, after dynamic arteriography to serve as a reference. Surgical treatment should be adapted to the degree of functional disability and the course of the exostosis or the complications it provokes.
Crossed shunts between the two femoral axes constitute a useful safeguard in unilateral iliac occlusions when the abdominal approach is contraindicated. Hemodynamic considerations suggest the need for iliac implantation from the donor side. This simple technique does not complicate the operation and provides a more satisfactory result than the interfemoral shunt.
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The authors report the case of a new born baby in whom at the fourth day of life, a severe hypocalcemia was discovered. An umbilical arterial catheterization was performed. The evolution was characterized by a staphylococcic septicemia with hip arthritis and partial immune deficit. The mid term survey of the joint status, allowed the unexpected discovery, during an examination held under general anesthesia, of a probable mycotic aneurysm, by abdominal palpation. The lesion was localized on the right common iliac artery and was successfully treated by resection; arterial continuity was possible without venous patch nor prosthesis.
Despite recent advances in the treatment of vascular injuries, the prognosis of injuries to the popliteal vessels is still poor with an incidence of 10-40 p. 100 of amputations recorded in the literature. Mortality rate is 4 p. 100. The authors have seen 13 cases and have studied seven factors influencing the prognosis - the duration of ischaemia, the general condition of the patient, the type of lesion, the state of the veins, the severity of the ischaemia, the level of the lesion and associated soft tissue injury and wounds. Each of the parameters has been assessed with a grade proportional to its severity. The summation of the grades leads to a division into three degrees of increasing severity and allows an early prognosis to be made. In the most severe degree of the lesion, amputation should be performed immediately. Twenty-one attempts at conservative surgery resulted in success in only four cases, with 17 amputations and four deaths among these.
The construction of an extra-anatomical femoropopliteal shunt resulted in the saving of a lower limb following a gunshot wound to the upper third of the thigh involving vascular lesions and extensive tissue loss. By applying this technique it was possible to obtain revascularization of the limb without the septic risks of reconstruction in situ, with the attendant difficulty of initial skin coverage of the wound.
Sub-crural bypass operations on a single leg artery were analysed retrospectively with a follow-up period ranging from six months to eight years. The vitality of the limb was threatened in the majority of cases (91/96). Whenever possible (79/96) the internal saphenous vein was used as a graft, preferably by the in situ technique. Mortality was 6%. Morbidity with the exception of thromboses was 14.5%. Patency by actuarial analysis was 71.6% at 5 years and 65.8% beyond. The majority of thromboses occurred during the first few months and led, in the majority of cases, to amputation. Secondary thromboses were better tolerated. The influence of various parameters was studied: clinical stage, peroperative flowmeter results, material used, technique, associated procedure (sympathectomy), implantation site and permeable vessel.
The prevention of recurrent pulmonary embolism by caval clip or intracaval filter may be difficult when the infrarenal segment of the inferior vena cava is double or left sided. Two such cases of anatomical variations are reported.
Three types of laser radiation were compared as to their capabilities in hepatic surgery using 17 New Zealand rabbits. In four animals, subtotal scalpel lobectomy was performed, the hepatic pedicle being clamped. Hemostasis is obtained by means of argon or Nd YAG laser as long as the internal diameter of the vessels encountered is less than 4.5 mm. Nd YAG laser requires a power output four times higher than argon laser to obtain hemostasis. In six animals limited resection was performed by means of Nd YAG and CO2 lasers. CO2 radiation supplied insufficient hemostasis whenever the vessel diameter was more than 1 mm despite an excellent cutting power. Nd YAG radiation created an important necrosis zone due to thermal diffusion. In seven animals various focal hepatic lesions produced by the three types of laser were compared. Argon laser induced superficial and regularly round lesion, Nd YAG laser deeper, cauliflower-like lesions with thermal diffusion following especially vessels. Veins presented thrombosis of their blood content and coagulation necrosis of their wall. The amount of glycogenic granulation decreased. The CO2 laser induced very sharp punctual lesion without necrosis. Electron-microscopic sections revealed faint shadowy liver cells closet to the thermal source and bubbled mitochondria containing disrupted critea around the lesion. In later lesions Nd YAG laser produced more extensive fibrosis than argon or CO2 laser. After first clinical trials we believe that laser irradiation is actually an adjuvant safety factor in current hepatic surgery, whereas the Nd YAG laser could be of real interest in metastatic carcinoma destruction in liver.