Importance of open marine waters to the enrichment of total mercury and monomethylmercury in lichens in the Canadian High Arctic.

Caribou, which rely on lichens as forage, are a dietary source of monomethylmercury (MMHg) to many of Canada's Arctic Aboriginal people. However, little is understood about the sources of MMHg to lichens in the High Arctic. We quantified MMHg, total mercury (THg) and other chemical parameters (e.g., marine and crustal elements, δ(13)C, δ(15)N, organic carbon, calcium carbonate) in lichen and soil samples collected along transects extending from the coast on Bathurst and Devon islands, Nunavut, to determine factors driving lichen MMHg and THg concentrations in the High Arctic. Lichen MMHg and THg concentrations ranged from 1.41 to 17.1 ng g(-1) and from 36.0 to 361 ng g(-1), respectively. Both were highly enriched over concentrations in underlying soils, indicating a predominately atmospheric source of Hg in lichens. However, MMHg and THg enrichment at coastal sites on Bathurst Island was far greater than on Devon Island. We suggest that this variability can be explained by the proximity of the Bathurst Island transect to several polynyas, which promote enhanced Hg deposition to adjacent landscapes through various biogeochemical processes. This study is the first to clearly show a strong marine influence on MMHg inputs to coastal terrestrial food webs with implications for MMHg accumulation in caribou and the health of the people who depend on them as part of a traditional diet.

[Campylobacter fetus subspecies fetus endoaortitis on a Bentall tube prosthesis. Apropos of a case]. / Endoaortite à Campylobacter fetus sous-espèce fetus sur tube prothétique de Bentall. A propos d'un cas.

Campylobacter fetus is a rare cause of endocarditis and endoaortitis: the authors believe this to be the second reported case of infection of an intracardiac prosthesis. The patient was a man who had already undergone replacement of the aortic valve and ascending aorta, and a gastrectomy, which were predisposing factors. The portal of entry was not found. The diagnosis was confirmed by positive blood cultures and transoesophageal echocardiography. The outcome was rapidly fatal despite antibiotic therapy and surgery, because of the seriousness of the lesions (pseudo-aneurysm of the aorta ruptured into the right atrium), the precarity of the terrain and surgical difficulties.

[Extracorporeal circulation in acute ischemia of the lower limb with late detection]. / Circulation extracorporelle de membre dans l'ischémie aiguë vue tardivement.

The authors report a case of acute limb ischemia in a 19 years old patient seen at 9 hours of the injury. They describe a technique of "washing-reperfusion" by a cardio-pulmonary limb bypass (CPLB). Blood pH and kaliema measurements during CPLB were noted. The good clinical result except on the initial nerves deficit, should lead to think that this technique could take a place in the treatment of acute limb ischemia seen lately.

[Coronary artery bypass with bovine internal mammary artery graft]. / Pontages coronaires par artère mammaire interne de boeuf.

Ten of 1,025 patients undergoing coronary bypass surgery received one or two bovine internal mammary artery grafts. Surgery consisted in quadruple coronary bypass in 1 case, triple coronary bypass in 3 cases and double coronary bypass in 6 cases using 4 autologous saphenous vein grafts, 6 autologous internal mammary artery grafts and 13 bovine internal mammary artery grafts. It was necessary to use bovine internal mammary artery grafts because of total bilateral venous stripping in 5 patients, diffuse, bilateral varicose veins in 4 patients and because of the insufficient length of the vein in 1 patient. Short and medium-term (12 months) angiographic studies of the bovine grafts showed 5 occluded grafts, 2 proximal graft stenoses, and 1 patient graft up to the time of his death of extracardiac causes, with a maximum follow-up of 13 months. One of these 10 patients died in the early postoperative period of extracardiac causes with a patent bovine coronary graft. Another patient died in the 5th postoperative month during reoperation motivated by occlusion of the two implanted bovine coronary grafts. The other 8 patients are alive and stable from the coronary view point. Bovine internal mammary artery grafts may be used to manage an acute episode of coronary insufficiency by providing the time for the collateral circulation to develop but it does not provide a complete and durable method of revascularisation. Their use should therefore be reserved for exceptional cases.

[Repair of post-infarction interventricular communication in a 81-year-old patient]. / Réparation d'une communication interventriculaire post-infarctus chez un sujet de 81 ans.

Post-infarction interventricular fistula (IVF) is a complication with a poor prognosis, particularly when it occurs very early after myocardial necrosis, when it is wide in diameter and even more so if it is at a posterior site, and if there are associated lesions which require surgery. An operation is often considered as contraindicated in cases where the patient is elderly. The authors report on the case of an 81-year-old diabetic patient operated for a wide post-infarctus posterior IVF and aorto-coronary artery bypass surgery. The operation is still a clinical success after 23 months of follow-up, showing that old age is not an absolute contraindication for surgery in cases of post-infarction IVF.

[Coronary artery bypass using bovine internal mammary artery]. / Pontages coronaires par artère mammaire interne de boeuf.

Among 760 patients who underwent coronary artery bypass graft (CABG) 8 received one or two bovine internal mammary artery grafts. The surgical procedures were 4, 3 and 3 CABG respectively in 1, 3 and 4 cases with greater saphenous veins in 4 cases, internal mammary artery in 4 cases and bovine internal mammary artery in 11 cases. The 3 mm bioflow grafts were used to revascularize the left coronary artery in 6 cases (to the left anterior descending, circumflex artery) and the right coronary artery in 5 cases. The indications for the use of bovine mammary artery grafts were lack of suitable autologous vessels because of bilateral saphenous vein stripping in 4 cases, bilateral varicose veins in 3 cases and inadequate length of vein in 1 case. Post-operative angiographic studies of these bovine mammary grafts with a maximum follow-up of 11 months showed 5 occluded grafts, 2 grafts with proximal stenosis, one graft which remained patent until the patient died and 3 grafts still under evaluation. Bovine internal mammary artery grafts provide a solution for the acute stage of coronary disease, but do not achieve total and durable revascularization. Their use must remain exceptional.

[Reoperation on valve bioprostheses. Apropos of 64 cases]. / Réinterventions sur bioprothèses valvulaires. A propos de 64 cas.

Sixty-four patients with one or more bioprostheses were reoperated between 1970 and 1982. Reoperation was performed for degenerative lesions in cases (48%), for aseptic periprosthetic leaks in 18 cases (28%), for infectious lesions in 13 cases (21%) and for thrombosis in 2 cases (3%). Degenerative and infectious lesions were commoner in aortic bioprostheses whilst periprosthetic leaks were commoner in mitral bioprostheses. The average interval between operations was 38 months. This was shorter in patients reoperated for mechanical problems (6 months) than those with infections (28 months) or degenerative (5 years) complications. At reoperation 14 prostheses were reinserted and 50 were replaced. The global hospital mortality was 21% (14 deaths). The mortality was related to the surgical indication: mechanical lesions (11%), degenerative lesions (16%), infectious endocarditis (38%), thrombosis (100%). The mortality rate also varied with time (36% during the period 1970-1978 and 18% during the period 1979-1982). This improvement was related to two factors: the use of cardioplegic solutions for myocardial protection and earlier recognition of surgical indications before the onset of irreversible haemodynamic complications. When choosing a valvular prosthesis, the mortality of reoperation for degenerative changes is the only disadvantage of the bioprosthesis which is silent, rarely complicated by thromboembolism and which does not require anticoagulant therapy for life. The mortality has decreased with time and will continue to fall if the indications for reoperation are based on stethacoustic, electrical, radiological and echocardiographic criteria of valvular dysfunction and not on the presence of overt cardiac failure as is still often the case.

[Open approach to the subclavian vein for permanent cardiac stimulation]. / Abord à ciel ouvert de la veine sous-clavière pour stimulation cardiaque permanente.

In 97.5% of 562 successive attempts, puncture of the subclavian vein to introduce permanent pacemaker electrodes was made easier and safer by the incisional technique described in this report. The very low incidence (0.35%) of traumatic pneumothorax and the absence, after a long follow-up, of any infection or exteriorization of the pacemaker chamber were the main advantages of this technical variant.

[Severe postoperative heart blocks appearing late. 16 cases]. / Blocs cardiaques postopératoires de haute gravité et de survenue tardive. 16 observations.

Sixteen patients, aged 4 to 42 years, operated for congenital heart disease, presented, months or years after surgery, complete atrioventricular (11 cases) or sinoatrial block (5 cases). Six patients had transient complete atrioventricular block in the immediate postoperative period, the maximum duration of which was less than 30 days. The late postoperative period was defined as at least 6 months after surgery. The period between surgery and the implantation of a pacemaker varied from 9 months to 19 years, average 6,3 years. Analysis of long term electrocardiographic studies distinguished three types of progression: --group I: alternation of sinus rhythm and conduction defect until definitive block, sometimes presenting with syncope; --group II: sudden, severe conduction defect after a long period of sinus rhythm; --group III: progressive lengthening of the PR interval. Seven patients developed syncope; 4 had dizziness, 2 were short of breath; only 3 were asymptomatic. All underwent permanent pacing. The incidence of late conduction defects appears to be 1 to 2% of operated patients. The causes include progressive fibrosis, slow sclerosis extending over conduction pathways which are congenitally fragile. Most late blocks are of an advanced degree. Some may be responsible for unexplained sudden death. It is therefore desirable to avoid this complication by the judicious and considered implantation of a cardiac pacemaker. Some authors mention the following factors in deciding on the indications for pacing: --complete, transient atrioventricular block during the operation or the immediate postoperative period; --ECG appearances of right bundle branch block and left anterior hemiblock, or trifascicular block; --His bundle studies.(ABSTRACT TRUNCATED AT 250 WORDS)

[Removal of wasted endocavitary pacemaker electrodes by the epigastric route without cardiopulmonary bypass (author's transl)]. / Ablation des sondes endocavitaires perdues par voie épigastrique sans circulation extra-corporelle.

Wasted, embedded and infected endocavitary pacemaker electrodes responsible for severe septicaemia were removed on three occasions, using an original technique. The heart was approached through a subxyphoid or epigastric incision, and the right ventricule was entered through a short opening in its diaphragmatic surface. The cardiac incision was comprised within a U-shaped suture resting on two teflon felter strips. This technique does not require cardiopulmonary bypass.

Computed tomography versus aortography in diagnosis of aortic dissection.

The use of computed tomography (CT) versus aortography is evaluated in a limited study of 17 cases of aortic dissection (AD). With the constraints of the present state of the technology and lack of availability of CT scanners at some centers, aortography remains the premier and often the only diagnostic test to choose in an emergency. CT, however, may be an asset in the diagnosis of AD when: (1) atypical or misleading clinical presentations are evident that do not require aortography; (2) aortography is contraindicated in a weakened patient, when there is no emergency; (3) aortography is a risk while there is a strong suggestion of AD; (4) patency of a false channel must be confirmed. These circumstances were encountered in five patients. In addition, a localized infrarenal AD was fortuitously discovered in two patients presenting with abdominal visceral cancer. On patient follow-up, CT is less invasive and may be performed in asymptomatic patients undergoing treatment, thereby facilitating the early detection of complications. Detailed computed tomograms often yield superior diagnostic information only if the CT study includes rapid sequential scans immediately following a fast intravenous bolus of contrast material.

[Auriculo-ventricular block and pregnancy]. / Bloc auriculo-ventriculaire et grossesse.

20 cases of pregnancy in women with complete atrioventricular block (AVB) (12 patients) or with permanent pacemakers (8 patients) were observed in a French cooperative series and compared with I30 previously reported cases. Most patients were asymptomatic but an increase in the number of syncopes during gestation might be observed : 4 out of 12 in our series. Although AVB remains functionally latent during pregnancy, regular cardio-obstetric follow-up is advised. Hospital admission a few days before the expected date of delivery is desirable, and it is essential that the patients are delivered in department specialised in high risk pregnancies. The need for prophylactic temporary pacing during delivery is not universally accepted. On the other hand, dizziness and syncope are clear cut indications for permanent cardiac pacing ; programmable pacers are excellent choices in young women of childbearing age ; nuclear pulse generators (Pu 238) do not seem to expose the mothers or foetus to serious complications. Rejection of pulse generators during pregnancy is rare. Nearly all mothers with AVB, whether paced or not, now have normal pregnancies resulting in normal viable children. This conduction defect is not therefore an indication for therapeutic abortion.

[Disinsertion of the left innominate vein during median vertical sternotomy (author's transl)]. / Désinsertion du tronc veineux innominé au cours de la sternotomie médiane verticale.

The left innominate vein may be torn during median vertical sternotomy. This tear may in fact be a disinsertion of the venous trunk from the superior vena cava. Repair of this disinsertion is difficult, with a risk of stenosis. It requires the most careful technique, after dissection of the superior vena cava on either side of the tear. It is made much more simple by the use of extracorporeal circulation, which empties and collapses the superior vena cava. Finally, it may be necessary to repair this loss of substance by enlarging it with a fragment of saphenous vein.

Surgery for aortic dissection: 53 operated cases with 32 in the acute phase.

53 cases of aortic dissections were operated on between 1961 and 1975 in the Service of Cardiovascular Surgery at the Broussais Hospital, Paris (Prof. Ch. Dubost). The present study deals with 32 cases operated on in the acute phase. 31 originated in the ascending aorta and 1 in the descending aorta. Operative mortality was 50% (16/32), 4 patients died immediately following sternotomy. Operation consisted in replacement of the ascending aorta for the majority of type I and II dissections. When aortic insufficiency was present, a simple resuspension procedure was effective in 50% of cases. The authors prefer early operative intervention in type I and II dissections and medical treatment in type III dissections.