Conrad Pelletier

A simple classification of the risk in cardiac surgery.

A new risk classification for patients undergoing cardiac surgery has been used for the last two years by the anaesthesiologists of the Montreal Heart Institute. The following factors known to be associated with a greater operative morbidity and mortality were selected: (1) poor left ventricular function, (2) congestive heart failure, (3) unstable angina or recent (less than 6 weeks) myocardial infarction, (4) age over 65 years, (5) severe obesity (Body Mass Index > 30), (6) reoperation, (7) emergency surgery, (8) other significant or uncontrolled systemic disturbances. Patients with none of the above factors were classified as normal risks; those presenting with one of those selected factors were classified as increased risks, and those with more than one factor were said to carry a high risk.In a prospective study of 500 consecutive open-heart surgery patients classified according to this method, we found that the operated population at normal risk (50 per cent of cases) had a mortality of 0.4 per cent, the patient group with increased risk (32 per cent of cases) had a mortality of 3.1 per cent, and the high risk group (18 per cent of cases) had a 12.2 per cent mortality. Furthermore, 50 deaths following open-heart surgery were assessed retrospectively using the classification; 58 per cent of these patients were classified as high risk, 34 per cent had an increased risk, and only eight per cent were found to be in the normal risk group. Thus, this new risk classification has proven to be a reliable and useful tool for preoperative assessment of patients undergoing open-heart surgery and for teaching purposes.RésuméUne nouvelle classification du risque opératoire est en usage à l’Institut de Cardiologie de Montréal depuis deux ans. Cette classification est basée sur la présence ou l’absence pré-opératoire des facteurs suivants; mauvaise fonction ventriculaire, signes cliniques ou radiologiques d’insuffisance cardiaque, angine instable ou infarctus récent, âge supérieur à 65 ans, obésité importante (i.e. Index de Masse Corporelle supérieur à 30), réintervention, chirurgie effectuée en urgence, autre atteinte systémique importante ou non contrôlée. Les malades qui ne présentaient aucun de ces facteurs de risque avant l’intervention étaient classifiés dans le groupe du risque habituel; ceux qui présentaient un de ces facteurs étaient classifies dans celui du risque accru et ceux qui présentaient plus qu’un de ces facteurs étaient définis comme des risques élevés.La classification a été évaluée prospectivement chez cinq cent patients consécutifs soumis à une chirurgie à cœur-ouvert. Un malade sur deux appartenait à la catégorie du risque habituel; la mortalité dans ce groupe a été de 0.4 pour cent. Une mortalité de 3.1 pour cent a été enregistrée chez les malades appartenant au groupe du risque accru (34 pour cent de nos 500 patients). Chez les patients répondant aux critères du risque élevé (18 pour cent des cas) nous avons observé une mortalité de 12.2 pour cent.Cinquante malades décédés après une chirurgie à cœur-ouvert ont été classifiés de façon rétrospective avec notre classification. Huit pour cent de ces malades appartenaient à ta classe du risque habituel, 34 pour cent à celle du risque accru et 58 pour cent à celle du risque élevé.La nouvelle classification s’est donc avérée utile et fiable pour l’évaluation pré-opératoire du risque en chirurgie cardiaque et pour l’enseignement de nos résidents.

Clinical and Hemodynamic Results with the Carpentier-Edwards Porcine Bioprosthesis

Carpentier-Edwards bioprostheses were implanted in 605 patients, 509 of whom had a single valve replacement, and 96 of whom had a multiple valve replacement. There were 54 early deaths (8.9%) and 26 late deaths (4.3%). The five-year actuarial survival was 87% for aortic valve replacement, 83% for mitral valve replacement, and 81% for multiple valve replacement. Of the 525 survivors, all but 3 were followed for a total of 964 patient-years; 354 patients (68%) remained asymptomatic, and 95 patients (18%) were improved. The incidence of thromboembolism, endocarditis, and reoperation due to primary tissue failure of the bioprosthesis were 2.0, 1.3, and 0.1% per patient-year, respectively. The actuarial probability of being free of all valve-related complications was 93% after five years. Satisfactory hemodynamic performance of the bioprosthesis was demonstrated by postoperative studies done in 70 patients. Thus, the Carpentier-Edwards porcine valve provides good clinical improvement, with a low incidence of valve-related complications and tissue failure at five years postoperatively.

Postinfarction Ventricular Septal Defect: Delayed Closure with Prolonged Mechanical Circulatory Support

Three patients who had ventricular septal rupture and cardiogenic shock complicating an acute myocardial infarction were treated by prolonged circulatory assistance using intraaortic balloon pumping. Hemodynamic stabilization was obtained, and surgical repair was delayed for 19 to 27 days after initiation of circulatory support. All three patients survived the operation and were discharged from the hospital 13 to 19 days after operation. Prolonged intraaortic balloon pumping in such patients is safe and often induces hemodynamic stabilization. The patients may then be operated on under more favorable conditions, without risk of multisystem failure, and after fibrosis has developed around the septal rupture.

Epidemiological study of Candida spp. colonization in cardiovascular surgical patients

Summary. Candida infections involve multiple risk factors. Among the independent risk factors identified, the degree of colonization of Candida spp. allows the prediction of subsequent severe candidosis in surgical patients. The aim of this study was to assess among 13 selected variables, those that would best predict the perioperative variation of the colonization index (CI) of Candida spp. in cardiovascular surgical patients. The colonization index took into account the number of sites colonized and the density of growth. The results showed that 56.8% of our patients were colonized perioperatively. A total of 116 isolates were identified and Candida albicans accounted for 76.7% of the strains. Among the patients who developed post‐surgical Candida infections, 57.1% had an increase of the CI early after the operation. By univariate analysis, three factors were significantly associated with an increase of the CI in patients after surgery: sex (female), the duration of central intravascular catheterization and the length of stay in the surgical intensive care unit (SICU). Epidemiological data could help predict those patients who are at risk of developing Candida infections.

Pentoxifylline decreases cyclosporine-induced renal endothelin release and vasoconstriction☆

Cyclosporine (CSA) causes an acute vasoconstriction of renal artery and a significant increase in renal endothelin release. Pentoxifylline, a vasodilator, has been suggested to prevent CSA toxicity. To study the effect of pentoxifylline treatment on CSA-related vasoconstriction and endothelin release, a model of renal autoperfusion in the dog was used. Oral pentoxifylline at the dose of 400 mg three times daily for 3 days was given to 15 dogs. Pure powder CSA (10 mg) was injected into the isolated renal artery perfused at constant flow; changes in perfusion pressure reflected variations in vascular resistance. In the pentoxifylline-treated group (15 dogs), the infusion of CSA caused an average increase of 27 +/- 8 mm Hg in renal perfusion pressure, compared with 60 +/- 10 mm Hg in a control group of 8 untreated animals (p < or = 0.05). Plasma concentration of endothelin in the renal vein increased from an average of 1.2 +/- 0.2 pg/mL before to 2.4 +/- 0.5 pg/mL after CSA administration (p < or = 0.05) in the control group, whereas it did not change significantly in the pentoxifylline-treated group. Thus, oral pretreatment with pentoxifylline significantly decreased the renal vasoconstriction and endothelin release due to CSA administration.

Mechanism of hind limb vasoconstriction due to cyclosporin A in the dog.

Cyclosporin A (CSA) causes an acute vasoconstriction of hind limb arterial vessels. To determine the mechanism of action of CSA on the peripheral arterial bed, studies were performed on the isolated femoral artery perfused at constant flow in 61 dogs. Changes in femoral perfusion pressure reflected variations in vascular resistance. Pure powder CSA was dissolved in autologous blood and injected at doses of 1, 5, 10, and 20 mg. Infusions of 1 and 5 mg CSA caused nonsignificant mean increases of 4 +/- 2 mm Hg (95% confidence interval [CI], 0-8; p > 0.05) and 10 +/- 4 mm Hg (95% CI, 0-21; p > 0.05) in femoral perfusion pressure, with CSA blood levels in the femoral vein averaging 40 +/- 16 and 126 +/- 50 nmol/l, respectively, at the end of the injections. Infusions of 10 and 20 mg CSA caused significant increases in femoral perfusion pressure averaging of 8 +/- 3 mm Hg (95% CI, 1-14; p < 0.05) and 20 +/- 4 mm Hg (95% CI, 11-29; p < 0.05) in femoral perfusion pressure. CSA blood levels at the end of injections averaged 271 +/- 99 and 431 +/- 146 nmol/l, respectively, in the femoral vein. Blockade of alpha-adrenergic receptors with phentolamine and surgical lumbar sympathectomy decreased significantly the CSA vasoconstrictive effect in peripheral arterial vessels, with increases in perfusion pressure averaging 29 +/- 5 mm Hg before and 14 +/- 3 mm Hg after phentolamine (p < 0.05) and 30 +/- 2 mm Hg before and 8 +/- 2 mm Hg after sympathectomy (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

La visite pre-operatoire en chirurgie cardio-vasculaire

RésuméCe texte destiné aux résidents d’anesthésie-réanimation en début de stage dans un service cardio-vasculaire, discute du risque opératoire et de certains problèmes courants chez les patients devant subir une intervention chirurgicale cardiaque ou vasculaire. On classifie le risque en risque habituel, accru ou élevé, selon la présence de facteurs aggravants du risque (mauvaise fonction ventriculaire, angor instable, âge, etc. …). On propose une évaluation du risque habituel pour certaines interventions courantes. Parmi les problèmes courants rencontrés chez ces malades, on retrouve entre autres des pathologies pulmonaires, des problèmes de coagulation, le diabète et l’insuffisance rénale. La prémédication utilisée chez ce type de malade et l ’ approche adoptée à l’ Institut de Cardiologie de Montréal y sont discutées.AbstractThis text is intended for new residents in the department of anaesthesia of the Montreal Heart Institute. It presents a classification of the risk of cardiovascular surgery used in that institution and discusses current problems encountered with this type of patient (pulmonary and coagulation problems, diabetes renal failure). The attitudes of anaesthetists of this institution towards patients’ medication and premedication are also discussed. The risk is classified as usual, increased or high, depending on the presence (or absence) of several factors known to increase the risk: ventricular dysfunction, heart failure, unstable angina or recent infarction, significant involvement of other systems (unstable diabetes, renal insufficiency, significant pulmonary dysfunction), age, emergency surgery and non-cardiac surgery in the presence of important cardiac pathology. With surgical procedures carrying a high mortality, for example dissecting thoracic aneurysm, the usual risk is high and is classified as such. A table of the usual risk of current surgical procedures is proposed.

Endocardite infectieuse à Actinobacillus actinomycetemcomitans: A propos de 2 cas et revue de la littérature

This work reports two cases of endocarditis caused by Actinobacillus actinomycetemcomitans. As noted in the medical literature, the mean clinical features are a subacute infection without know source of bacteremia, in a male patient aged 40 years or older and who is suffering from a heart disease. In our two presentations, the good response to single antibiotic treatment, although the optimal therapeutic approach is not yet defined, and the lack of embolism phenomena are of special interest. Spectrum of bacteria which can be responsible of infective endocarditis is widening rapidly; this study is an example of this trend.