Clonidine for major vascular surgery in hypertensive patients: a double-blind, controlled, randomized study.

The utility of clonidine for hypertensive patients presenting for major vascular procedures remains debatable. Twenty-one hypertensive patients presenting for aortic surgery were given clonidine (n = 11) or placebo (n = 10) in a double-blind, randomized manner. Clonidine was administered 6 micrograms/kg per os 120 min before induction of anesthesia and 3 micrograms/kg intravenously (i.v.) over 60 min from aortic declamping to skin closure. Anesthesia was induced with alfentanil 20 micrograms/kg, midazolam, and atracurium and maintained with nitrous oxide 70%, an alfentanil infusion (0.25 microgram.kg-1. min-1), and isoflurane. Anesthetic requirements, circulatory variables, interventions, and isoproterenol dose-response curves (pre- and postoperatively) were determined. Plasma concentrations of clonidine, alfentanil, and vasoactive hormones were measured. When the clonidine group was compared with the placebo group, (a) isoflurane, alfentanil, and midazolam requirements were reduced by 38%, 42%, and 41%, respectively (P = 0.04, 0.03, 0.0002, respectively); (b) supplemental circulatory and anesthetic adjustments were reduced by 51% (P = 0.0006); (c) interventions with vasopressors were not significantly increased (placebo: two; clonidine: five); (d) systolic and mean arterial pressures and heart rate were reduced; (e) increases in norepinephrine, epinephrine, and plasma renin activity were suppressed, whereas vasopressin surge was attenuated; and (f) chronotropic response to isoproterenol was unaffected. Clonidine was effective in reducing anesthetic requirements and in improving circulatory stability in hypertensive patients presenting for major vascular procedures.

[Diagnosis of bacterial infections on vascular prosthesis. Histological and microbiological analysis]. / Diagnostic de l'infection des prothèses vasculaires. Analyse histologique et microbiologique.

A retrospective study of 212 vascular graft failures, using different criteria of infection evidenced a relatively high incidence of infectious complications. Vascular graft infection was assessed on one of the following criteria: clinical infection, positive bacteriological and/or virological examination of the graft, presence of characterized micro-organisms and of microstructures 0.1 to 0.5 micron in size at the blood/prosthesis surface at scanning electron microscopy, and presence of foci of persistent polymorphonuclear cells and lymphocytes at histological microscopy. In the absence of overlapping between these criteria, the present results raise the question of the adequacy of conventional bacteriological sampling on explanted artificial surfaces.

[Interruption of the inferior vena cava by the DIL filter. Experience apropos of 34 cases]. / Interruption de la veine cave inférieure par le filtre DIL. Expérience à propos de 34 cas.

Endocaval filters are often used to prevent pulmonary embolism but they have a number of disadvantages. The DIL filter, made of a memory metal wire, is intended to male up for some of these disadvantages. It acts by modifying the shape of the inferior vena cava, which it filters through its meshed loops. It is inserted percutaneously, causes little trauma, and its release is progressive. However, it requires measuring the caliber of the inferior vena cava. This filter was inserted in thirty-four patients over a period of 13 months. One filter has migrated. No recurrence of pulmonary embolism and no thrombosis of the inferior vena cave occurred.

Oxygen uptake and mixed venous oxygen saturation during aortic surgery and the first three postoperative hours.

This study was designed to determine the significance of changes in mixed venous oxygen saturation (SVO2) associated with aortic surgery. In 12 patients undergoing aortic aneurysm repair, SVO2 was monitored using a fiberoptic pulmonary arterial catheter, and oxygen uptake (VO2) was measured at 2-min intervals by a mass-spectrometer system. Excluding the phase of aortic clamping, VO2, hemoglobin, and arterial oxygen saturation were moderately stable during anesthesia, and changes in SVO2 were correlated with changes in cardiac output (CO). SVO2 remained stable during infrarenal aortic clamping, but increased during supraceliac aortic clamping. During the first three postoperative hours, changes in SVO2 were opposite to changes in VO2 and CO. They were especially marked in the patients whose preoperative left ventricular ejection fraction was less than 50%. We conclude that SVO2 changes are an indicator of same-direction changes in CO during general anesthesia except during periods of aortic clamping. The interpretation of SVO2 changes is more complex during aortic clamping and during the immediate postoperative period, two critical periods during which simultaneous changes in VO2 and CO occur.

Human vascular graft failure and frequency of infection.

Among 212 vascular prostheses collected in a vascular explant retrieval program, 50 exhibited one or more criteria of graft infection i.e., (a) clinical evidence of graft infection, (b) positive bacteriological analyses of the graft, and (c) presence at the blood-prosthetic interface of characterized microorganisms. Whereas each of these criteria was noted respectively in 25, 26, and 20 cases, there was no complete overlapping among the three criteria, but their combination led us to consider 50 cases of infected vascular grafts among the 212 collected. These results, and the occurrence in two cases among six investigations for viral infection, suggest that extensive bacteriological investigations of vascular explants should be included in an implant retrieval program, and that infection may represent a high risk in graft failure.

[The Dacron vascular prosthesis in men. Mechanical performance, lesions and molecular stability]. / Prothèses vasculaires en Dacron chez l'homme. Performances mécaniques, lésions et stabilité moléculaire.

The causes of failure of vascular prostheses implanted in man were investigated by means of histological, ultrastructural and scanning electron microscopic techniques as well as mechanical performance and macromolecular structure studies. These investigations concerned 22 out of 212 explanted prostheses from about 10 vascular surgery departments, examined over a 3-year period. The changes observed in the mechanical properties of the explanted prostheses (2 to 75 per cent reduction of resistance to rupture) and the finding of broken fibers and migrating polyester particles were confirmed by the presence of structural alterations in the polymer with, in particular, diminution of its crystalline structure. No correlation was found between the occurrence of these lesions and the type of prosthesis used and/or the duration of implantation.

[Thoracic sympathectomy by thoracoscopy. Apropos of 15 cases]. / Sympatholyse thoracique par thoracoscopie. A propos de 15 cas.

UNLABELLED: Thoracic sympathectomy is achieved using the trans-axillary route during the course of a thoracotomy. The indications are Raynaud's phenomenon, digital arteriopathy, and hyperhidrosis. Alongside the surgical approach in theory it is possible to use a thoracoscopic approach for a thoracic sympathectomy, to achieve a physico-chemical destruction, we have studied this possibility using this technique. MATERIAL AND METHODS: Thoracoscopy is achieved under local anaesthetic after creating a pneumothorax. The approach is through the 2nd intercostal space in the mid-clavicular line. Anaesthesia of the 2nd sympathetic ganglion is achieved, the ganglion is destroyed by injection of 8 c.c's of Phenol. 15 patients were treated (15 to 7). The presented with palmar hyperhidrosis (7), digital arteriopathy (6) or Raynaud's syndrome (2). RESULTS: The first 5 patients were failures which led to a more precise technique. Overall we observed 8 favourable results. If we exclude the first 5 cases we achieved 8 favourable results and 2 failures. The approach to the 2nd sympathetic ganglion using the thoracoscope is not always possible: the vision may be obscured. When it is possible phenolization may yield excellent results comparable to those of surgical sympathectomy. CONCLUSION: Palmar hyperhidrosis for which we have obtained the best results seems to us to be an extra indication of this technique which enables a cure at the price of a relatively simple procedure and a brief period of hospital stay.

[Thoracic sympathectomy by thoracoscopy. Apropos of 15 cases]. / Sympatholyse thoracique par thoracoscopie. A propos de quinze cas.

Thoracic sympathectomy is generally performed by thoracotomy. Apart from the surgical approach, the thoracoscopic technique allows vision and physical or chemical destruction of the thoracic sympathetic system. We studied the possibilities of their technique. Thoracoscopy is performed under local anesthesia after creation of a pneumoserosa. Local anesthesia of the second sympathetic ganglion is performed. The ganglion is destroyed by injection of 8cc of phenol. Fifteen patients have been treated (15 to 70). The first five patients were failures and led to improvement of the technique. We have 8 good results. If we exclude the first five patients, we observe 8 good results and 2 failures. The thoracoscopic approach to the second sympathetic ganglion is not always possible (local pleurodesis). When it is possible, the results of local treatment by phenol are as good as those of surgery.

[Aneurysm of iliac arteries. Is it anatomo-clinical entity? Report of 18 cases]. / L'anévrisme des artères iliaques. Une entité anatomo-clinique? A propos de 18 cas.

338 patients with aorto iliac aneurysms were operated in the Department of vascular surgery (Hosp. E.-Herriot-University A.-Carrel Lyon). Retrospective evaluation found 20 solitary iliac artery aneurysms (AAIS) in 18 patients (2 bilateral AAIS). 77% of aneurysms were on the common iliac artery, 17% on the internal iliac artery, and one case of mycotic aneurysm on the external iliac artery. 8 patients (44.4%) were asymptomatic, 5 (27.8%) had non specific complaints. Rupture or acute ischemia occurred in 5 cases (27.8%). The incidence of non atherosclerotic cause (dysplasia 33.3%, infection 16.7%) in this series shows a real difference with AAA (atherosclerotic dominant etiologic factor). The value of C.T. scanning and sonographic evaluation and their extensive use in vascular and non vascular diagnostic problems are an obvious explanation for increasing AAIS reports. The risk of rupture is probably higher than in AAA because of the incidence of arterial dysplasias (1/3 in this study) and mycotic origin. This occurrence suggests an aggressive surgical management. Aneurysmorrhaphy with graft interposition by intraperitoneal approach is the routine technique for most of surgeons. An alternative procedure (retroperitoneal approach) was performed on ten of our patients (55.5%). No perioperative mortality and low morbidity rate (one case of phlebitis) in our cases support this surgical management. The survival rate based on actuarial method is estimated 64% at five years (all grafts patent).

[Value of somatosensory evoked potentials in thoraco- brachial outlet syndrome]. / Intérêt des potentiels évoqués somesthésiques dans les syndromes de la traversée thoraco-brachiale.

INTRODUCTION: Brachial plexus involvement in symptoms of thoracic outlet syndrome (TOS) is often difficult to assess from clinical data. Conventional EMG and nerve conduction studies (NCS) do not seem reliable to all authors. For this reason, our investigations of this syndrome were complemented by study of somatosensory evoked potentials (SEP) in order to compare the results of these different techniques. PATIENTS AND METHODS: Ten patients were studied, all of whom had prominent vascular symptoms which led to their consulting a vascular surgeon. Only one had hand wasting without hypoesthesia. None had cervical rib or cervical spine anomaly. In all cases, diagnosis was confirmed by arteriography or phlebography. Operations were decided on clinical data and results of vascular investigations. Patients were tested with conventional motor and sensitive NCS F-wave studies. Needle EMG was performed in abductor pollicis brevis, first dorsal interosseus or abductor digitiminimi. Their SEP were performed as for controls. Ten controls were studied whose SEP were obtained at Erb's point (N9) and C2 cervical spine level (N13) after percutaneous stimulation of median and ulnar nerves at the wrist on both sides. The criterion of abnormality was the mean of controls + 2.5 SD for latencies. Amplitude was considered as low when it was less than 50% of the contralateral one. RESULTS: For 2 patients EMG, NCS and SEP were abnormal. One had hand wasting and denervation in hand muscles as well as slowed median and ulnar sensory conduction with low amplitude responses. SEP at Erb's point were slightly delayed after ulnar stimulation. No cervical response was obtained after ulnar stimulation. The second one had normal responses at Erb's point but delayed responses at the cervical level. In addition, N13 amplitude after ulnar stimulation was low. Four patients had normal EMG, NCS and SEP. Two patients had normal EMG and NCS, but their SEP was questionable since latencies were normal, even though amplitude was low after median and ulnar stimulation. This was not considered this to be abnormal since it was bilateral. For the remaining 2 patients (F.1), EMG and NCS and Erb's point SEP were normal, but C2 median and ulnar responses were delayed in one case and C2 ulnar response amplitude was very low on one side only in the other. In conclusion, SEP were abnormal for 4 patients out of 10 but gave more information than conventional EMG and NCS for only 2 patients. SEP abnormalities prevailed after ulnar stimulation.

[The neoartery, myth or reality? Study of 79 explanted arterial prostheses]. / La néo-artère, mythe ou réalité? Etude de 79 prothèses artérielles explantées.

This study represents the third stage of a personal study on the long term fate of reconstruction and arterial restoration materials presented to the Academie de Chirurgie. 79 explanted prostheses were studied. First of all by an in depth histological study (8 cases selected from 70 reinterventions carried out before 1980), and then by a more complete protocol: scanning electron microscopy, resistance testing, programmed differential calorimetry, X-ray diffraction and biochemical analysis (71 reinterventions carried out after 1980). Our findings agree with the studies of R. Guidoin. With the exception of structural manufacturing defects or defects related to surgical manipulation, mechanical fatigue in a Dacron (PET) arterial prosthesis is inevitable: on average by the 7th to 10th year, a prosthesis looses one half of its mechanical resistance. The covering tissue, like that of the external capsule, which has poor mechanical properties, cannot compensate for prosthetic deterioration which may be considered to be complete by the 25th year. Knitted arterial prostheses, especially aortic, more rapidly undergo dilatation than woven prostheses which are much more resistant. On the other hand, the poor compliance of the latter compared with the recipient artery, perhaps favorises late anastomotic rupture. At internal capsule or pseudo-intimal level, endothelium is never present, but rather there is a permanent turnover with a variable time course, the mechanisms of which are poorly understood (role of prostaglandins?). Rather than a neo-artery, the vascular surgeon is only capable of producing an imperfect arterial tube, fragile from many points of view, and having an evolution which remains poorly understood.

[Surgery of carotid stenosis combined with contralateral obstruction. Technic of carotid bypass]. / Chirurgie des sténoses carotidiennes associées à une occlusion controlatérale. Technique du pontage carotidien.

Clamping of a carotid artery carries a considerable risk when the contralateral vessel is occluded. In a continuous series of 14 patients with carotid stenosis associated with contralateral occlusion, the possibility of substitute blood flow during clamping of the stentic vessel was evaluated by intra-operative measurement of carotid back pressure. In the 7 patients whose back pressure was higher than 40 mmHg, endarterectomy of the carotid bifurcation was performed in 6 cases and reimplantation for stenosing loop in 1 case. In the 7 patients whose carotid back pressure was lower than 40 mmHg, a carotid-carotid bypass was performed, the first anastomosis always being on the common carotid artery. No post-operative neurological accident was recorded. This technique seems to be preferable to a shunt, which is not always feasible, notably in cases with high bifurcation.

Stability of performances of vascular prostheses retrospective study of 22 cases of human implanted prostheses.

Twenty-two cases of vascular graft failures (thrombosis, pseudoaneurysm, dilation, infection) were investigated by means of physicochemical, histological, and ultrastructural studies. A general decrease of mechanical resistance to stress of the prostheses was observed. Its magnitude ranged from 2 to 75% of the values of identical virgin prostheses and there was no relation with the duration of implantation. In addition to the breakage of yarn filaments (SEM), migration of fiber debris (histology) was observed in 7 cases. The structure of the polyester molecule had evolved after implantation. A decrease of crystallinity (x-ray diffraction and differential scanning calorimetry) was noted. These observations raise the question of the established stability of vascular prostheses and emphasize the need for further investigations in human graft retrieval programs.

[Totally implantable venous-access systems: apropos of experiences of 30 patients]. / Les systèmes d'accès veineux totalement implantables: a propos d'une expérience chez 30 patients.

Thirty-one totally implantable venous access system were investigated in patients who required intravenous administration of chemotherapy, drugs, nutrients solutions, blood products and blood sampling. Mean duration of venous access was 179 days (ranged from 9 to 429 days). Eight complications were observed, five benign without consequence on port system use, three severe (infections) requiring its removal. No death occurred during implantation and port system use. Patient acceptance was better than with other methods for repeated vascular access. In patients requiring prolonged chemotherapy, totally implantable venous access systems represent a new technique of long term venous access, with easy implantation and lack of restriction of daily activities. Review of literature show that complications are most frequently local and easy to manage. Four types of complications may have severe consequences for patient and/or port system use: catheter occlusion, venous thrombosis, local and/or general infection, and skin necrosis subsequent or not to extravasation. They represent the major cause of port system removal, but this is seldom necessary. Acquired experience allow to justify an earlier implantation of totally implantable venous access systems before chemotherapy and destruction of available surface vessels.