GABAergic and glutaminergic modulation of centrally evoked arrhythmias in rats.

A standard electrical stimulus applied to the posterior hypothalamus evoked cardiac arrhythmogenic responses in the spontaneously hypertensive rat. Isolated premature ventricular beats or doublets and nonsustained ventricular tachycardic salvos were observed. This effect was associated with a large rise in blood pressure (79 +/- 3 mm Hg). The same stimulus in normotensive Wistar-Kyoto rats produced no significant cardiac arrhythmias, and the rise in blood pressure was smaller (36 +/- 2 mm Hg). We investigated the influence of baclofen, a GABAB receptor agonist, and two N-methyl-D-aspartate receptor antagonists on the arrhythmogenic response to hypothalamic stimulation. Intravenous baclofen (3 mg/kg) had no effect in the normotensive Wistar-Kyoto rats, but in the spontaneously hypertensive rats it enhanced the adjusted mean value of the number of extrasystoles from 0.5 +/- 0.5 to 18 +/- 1 (P < .001). This value was also increased (from 3 +/- 1 to 17 +/- 1, P < .001) by an intracisternal injection of baclofen (1 micrograms/kg). This facilitatory effect of baclofen was prevented by treatment with atenolol (0.5 mg/kg). Two glutamate receptor antagonists, ketamine (7.5 mg/kg IV) and kynurenic acid (200 micrograms/kg intracerebroventricularly), prevented both the arrhythmogenic response to the hypothalamic stimulation and its facilitation by baclofen. The study confirms that hypothalamic stimulation facilitates the development of arrhythmias through a sympathetic drive and that these arrhythmias are easier to induce in spontaneously hypertensive rats than in normotensive Wistar-Kyoto rats. Both the central GABAergic and the glutamatergic systems are implicated in the development of these ventricular arrhythmias, since baclofen could disinhibit the glutamatergic central pathway. These results could account for the ability of the spontaneously hypertensive rats to develop ventricular arrhythmias of central origin.

[Predictive factors of survival after mitral valvuloplasty]. / Facteurs prédictifs de la survie après valvuloplastie mitrale.

Survival and freedom from reoperation following mitral valvuloplasty (MV) was evaluated in 54 patients (pts) between October 1973 and December 1992. Ages of 35 men and 19 women averaged 49 years (+/- sd:18 yrs). Preoperative NYHA class was II or III in 48 patients (89%) and class IV in 6 pts. At surgery, degenerative disease was present in 43 patients (80%), rheumatic in 8 pts (14%) and congenital in 3 pts (6%). Annuloplasty (Carpentier 18, Duran 27, others 3) was performed in 48 pts and was the sole procedure in 6 pts. Six pts underwent valvuloplasty without annuloplasty. Associated procedures were performed in 18 patients (33.3%). Operative mortality was 6% (3 pts). Follow-up ranged from 1 to 164 months with a mean of 39 mo. (+/- 5 mo.). Survival at 5 years was 89 +/- 8% and freedom from reoperation was 85 +/- 9%. NYHA status was significantly improved following mitral valvuloplasty (p < 0.00001). Operative complications and unfavorable post-operative NYHA status were significantly predictive of death (p < 0.05). Prior cardiac surgery at the time of MV and post-operative unfavorable NYHA status were associated with increased incidence of reintervention (p < 0.05). We conclude that improved post-operative NYHA status heralds excellent long term survival and increased freedom from reoperation following mitral valve repair.

Bronchial carcinoids: long-term prognostic factors.

Between 1962 and 1987 bronchial carcinoids were diagnosed in 41 patients (21 men, 20 women) at l'Hôpital du Sacré-Coeur and the Centre hospitalier Maisonneuve-Rosemont. The patients ranged in age from 19 to 73 years (mean 47 years). Fourteen of the 19 asymptomatic carcinoids were discovered on routine chest radiography. Twenty-two symptomatic patients presented with either pneumonia or hemoptysis. Tumours involved the right and left lungs equally. Thirty tumours were located centrally and 11 peripherally. Sensitivity of endoscopic biopsy specimens was 66%. No complications occurred during biopsy. Cytologic examination of sputum, lavage, brushing and transthoracic biopsy specimens was of no value in establishing the diagnosis. Thirty-seven patients underwent surgical resection: lobectomies (26, 3 with bronchoplasties), pneumonectomies (7), segmentectomies (2) and wedge resections (2). One patient (3%) died, and there was one major complication (3%) related to surgery. The mean follow-up was 8 years. The probability of survival was 97% +/- 3 at 5 years and 92% +/- 6 at 10 years. None of the 19 patients treated for a peripheral tumour died, but two patients who had centrally located tumours that exhibited transbronchial invasion and lymph-node metastasis died. No prognostic information could be gained from tumour size or type. A statistical association was found between transbronchial invasion and lymph-node metastasis. Bronchial carcinoids are low-grade malignant tumours. Resection should be conservative, but lymph-node involvement requires a more radical approach.

[In situ femoro-popliteal bypass grafts. Study of 85 cases using Cartier's technique]. / Le pontage fémoro-poplité in situ. Etude de 85 cas opérés d'après la technique de Cartier.

From January 1985 to december 1989, 83 patients (69 men, 14 women) underwent an in situ femoro-popliteal bypass using a semi-closed technique and the valvulotome developed by Dr Paul Cartier. Most patients (67%) were operated for severe ischemia while 33% were for claudication. HTA was present in 31% of patients, diabetes in 38% and CAD in 57%. Mean preoperative ABI was 0.33 +/- 0.20 and mean ankle pressure was 50 +/- 30 mm of Hg. Arteriographic popliteal run-off showed three vessels in 21 cases (25%), two vessels in 17 cases (20%) and one vessel in 38 cases (45%). Nine patients (10%) presented an isolated popliteal artery. Bypass was constructed below knee in 62 patients (73%) and above knee in 23 (27%). Five mortalities (5.8%) and two major complications (2.3%) were related to surgery. Four early graft failures (4.4%) were noted but 3 were successfully reoperated. Postoperative ABI was 0.71 +/- 0.23 mm of Hg and 81% of patients had complete relief of their symptoms. With a mean follow-up 19 months, graft patency was 91% +/- 6% and 84% +/- 11% at one and two years and was not influenced by operative indication: hypertension, diabetes, preoperative ABI, arteriographic findings or distal anastomotic site. Overall survival was 80% +/- 10% and 69 +/- 13 at one and two years. The in situ technique using the Cartier valvulotomes is an excellent operation and compares favourably with other techniques.

Prolonged hyporesponsiveness of airway smooth muscle to histamine following general anesthesia.

The prolonged effect of barbiturates and inhalation anesthesia on airway response to histamine was studied in five groups of dogs. Group B (n = 10), H24 (n = 5), and H72 (n = 5) were anesthetized with sodium thiamylal (B) or halothane and N2O (H24, H72) for 3 h, during which a dose-response curve to histamine was obtained. The animals were then allowed to recover; 24 h (B and H24) or 72 h later, the animals were killed and an in vitro dose-response curve to histamine was obtained on a tracheal smooth muscle (TSM) specimen. Group C (n = 5), the control group, had no prolonged exposure to anesthesia. The dogs were immediately killed and the in vitro histamine response of the TSM was measured. The results (mean +/- SE) showed that the smooth muscle contractile properties (i.e., the maximum contraction to electrical field stimulation) were comparable in all four groups: 111 +/- 12 g (B); 168 +/- 23 g (H24); 106 +/- 32 g (H72); and 107 +/- 31 g (C). The maximum response (mean +/- SE) to histamine (as % of maximum electrical contraction) was: 15 +/- 6% (B), 30 +/- 9% (H24), 32 +/- 12% (H72), and 50 +/- 8% (C). Statistical analysis of the data showed that the histamine response of Group B and Group H24 was significantly decreased compared to Group C (P less than 0.01 and less than 0.05, respectively); in Group H72 the results were not significantly different from Group C (0.1 greater than P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)