PubMed Health⌕ Search

Biomedical subjects

L C Pelletier

Publications and source records attributed to L C Pelletier.

At least 91 records · Page 5Linked to original sources
PubMed1992

Prevention of herpes simplex virus infection by oral acyclovir after cardiac transplantation.

Infection with herpes simplex virus is common among immunosuppressed patients. In an attempt to prevent such infection, 58 patients (group 1) who underwent cardiac transplantation between 1987 and 1990 were given acyclovir (200 mg orally three times a day) prophylactically throughout their postoperative hospital stay (mean 22 days +/- 1 day). The patients' immunosuppressive protocol included cyclosporine, azathioprine and prednisone. The course of these patients was compared to that of 24 patients (group 2) who underwent cardiac transplantation between 1983 and 1986 but were not given prophylactic antiviral treatment postoperatively. The immunosuppressive protocol in these patients consisted of cyclosporine and prednisone. Herpes infection developed during the 1st year in 5 patients (9%) in group 1 and in 11 patients (46%) in group 2 (p < 0.05). The actuarial rates of freedom from herpes infection at 1, 6 and 12 months after transplantation were 100%, 98% +/- 2% and 95% +/- 3%, respectively, in group 1 and 82% +/- 7%, 58% +/- 11%, 53% +/- 11% in group 2. All viral infections were cutaneous or mucosal, except for one, which developed in a patient with pneumonia. All infections responded well to treatment, although one patient with an infected cornea was left with a permanent visual deficit. The authors conclude that prophylaxis of herpes simplex virus infection with acyclovir administered orally in the early postoperative period is effective in preventing viral infections during the 1st year after cardiac transplantation.

Acyclovir↗
PubMed1992

Clinical performance of the Duromedics bileaflet pyrolite mechanical prosthesis.

The Duromedics (Baxter Healthcare Corp., Edwards CVS Div., Irvine, Calif.) mechanical cardiac valvular prosthesis was implanted in 480 patients between 1984 and 1987 at the Montreal Heart Institute, the Hospital Clinic of Barcelona and the teaching hospitals of the University of British Columbia. The mean age of the patients was 52 years. The early mortality was 7.9% and the late mortality was 4.1% per patient-year. The overall survival at 4 years for aortic valve replacement (AVR) was 87.0% +/- 3.7% and for mitral valve replacement (MVR) was 81.9% +/- 2.9%. There were 16 valve-related reoperations in 14 patients--for prosthetic valve endocarditis in 9 patients, for thromboembolism in 1 patient and for nonstructural dysfunction in 4 patients. The freedom from thromboembolism at 3 and 4 years was 94.3% +/- 3.1% for AVR and 95.1% +/- 1.8% for MVR. The freedom from prosthetic valve endocarditis at 3 and 4 years was 95.3% +/- 2.2% for AVR and 96.2% +/- 1.6% for MVR. The freedom from structural valve deterioration for all positions was 100%. The freedom from reoperation at 4 years was 95.3% +/- 2.1% for AVR and 92.3% +/- 4.3% for MVR and from valve-related death was 98.7% +/- 1.3% for AVR and 96.2% +/- 1.6% for MVR. The freedom from all valve-related complications at 4 years was 87.7% +/- 3.8% for AVR and 85.7% +/- 2.9% for MVR. Long-term evaluation of the Duromedics prosthesis is required to determine the influence of documented structural valve deterioration.

Adolescent↗
PubMed1992

Cardiac surgery after failed percutaneous mitral valvuloplasty.

Percutaneous mitral valvuloplasty (PMV) has been proposed as a safe alternative to open mitral commissurotomy (OMC) or mitral valvular replacement (MVR) in selected patients with symptomatic mitral stenosis (MS). Among 146 consecutive patients who underwent PMV between March 1987 and April 1990, 18 (12%) needed urgent corrective surgery after the procedure. Of these 18 patients 16 were women and 2 were men. Three patients were of clinical incapacity class II and 15 of class III and were at an intermediate risk for PMV according to the echo score (mean score 8). The indications for corrective surgery were massive mitral regurgitation owing to tearing of the anterior leaflet (six patients), cardiac perforation (left atrium in two patients, left ventricle in three patients), technical failure of PMV (five patients) and severe atrial shunting (two patients). Operative procedures included MVR (14 patients), cardiac wound suturing only (3 patients) and OMC (1 patient). Operative mortality (within 30 days) was 22% (4 of 18 patients), distributed equally among patients needing urgent or elective surgery. When compared with the operative death rate after OMC (0%) and MVR (3.1%) as the initial treatment for MS during the same period, the rate for cardiac operation after failed or complicated PMV (22%) was significantly higher (p = 0.004). Therefore, optimal patient selection and aggressive corrective surgery are necessary to decrease PMV-related morbidity and death.

Adult↗
PubMed1992

The Mitroflow pericardial bioprosthesis. Comparison of early clinical performance in aortic and mitral positions.

Between 1983 and 1987 the Mitroflow pericardial prosthesis was implanted in 354 patients, ranging in age from 14 to 94 years (mean 60.1 years). The early mortality was 5.7% and the late mortality 2.9% per patient-year. The total cumulative follow-up was 853 years (mean 2.4 years). Patient survival at 4 years for aortic valve replacement (AVR) was 81.5% and for mitral valve replacement (MVR) 74.8%. The overall rate of valve-related complications was 4.8% per patient-year (41 complications): thromboembolism, 15; hemorrhage related to antithromboembolic therapy, 1; prosthetic valve endocarditis, 15; nonstructural dysfunction, 3; and structural valve deterioration, 7. At 4 years the freedom from thromboembolism was 91.5% +/- 2.7% for AVR and 91.1% +/- 4.0% for MVR, from prosthetic valve endocarditis 93.5% +/- 2.3% for AVR and 94.0% +/- 2.9% for MVR, from structural valve deterioration 97.3% +/- 2.1% for AVR and 92.6% +/- 3.2% for MVR, from valve-related mortality 96.9% +/- 1.4% for AVR and 97.5% +/- 1.8% for MVR, and from reoperation 93.5% +/- 2.8% for AVR and 83.1% +/- 5.1% for MVR. The freedom from the composite of all valve-related complications at 4 years was 81.1% +/- 4.2% for AVR and 75.3% +/- 2.8% for MVR. The Mitroflow valve has provided satisfactory clinical performance at the 4-year evaluation. Structural valve deterioration is greater in the mitral position than in the aortic position. Long-term evaluation of the Mitroflow valve is necessary to determine the impact of structural valve deterioration on its clinical performance.

Adolescent↗
PubMed1991

Valve replacement with bioprostheses for non-ischaemic mitral insufficiency.

From 1976 to 1989, 122 patients underwent isolated mitral valve replacement with a bioprosthesis for non-ischaemic mitral insufficiency. There were 76 women and 46 men, with a mean age of 52 years. Mitral valve disease was of rheumatic origin in 71 (58%), due to myxomatous degeneration in 50 (41%), and congenital in one. Early mortality was 3.3% (4 pts). The 10-year survival was 65 +/- 7%. A follow-up was available for all 122 patients, averaging 78 months, for a total of 763 patient-years. Valve-related (VR) complications included: 16 thromboembolic episodes in 13 patients (2.1% pt-yr), 3 endocarditis in 2 patients (0.4% pt-yr), and 20 reoperations (2.6% pt-yr), 19 of which were due to intrinsic structural deterioration of the tissue valve. There was no haemorrhagic episode. Overall, 32 patients suffered a VR complication (4.2% pt-yr). The 10-year freedom rates from haemorrhage, endocarditis, thromboembolism, and reoperation were 100%, 98%, 87%, and 64% respectively. After 10 years, 87% of the patients were free from VR mortality, 84% were free from VR mortality and permanent disability, and 52% remained free from all VR complications. While 69% of the patients (84 pts) were in functional class III or IV preoperatively, 89% (102 pts) of the survivors were in class I or II after operation. Excellent survival and clinical results have been obtained with the use of bioprostheses in this disease. However, because durability beyond 10 years appears to be limited and the cause of major morbidity, tissue valves are now used more selectively.

Adolescent↗
PubMed1991

Dose-dependent effect of cyclosporin on renal arterial resistance in dogs.

Important side effects of cyclosporin (CSA) are renal insufficiency and hypertension. They might be related to a renal vasoconstrictive effect of CSA, and this vascular response might be due to a local mechanism. CSA was injected in isolated renal artery perfused at constant flow in dogs. Changes in renal perfusion pressure reflected variations in vascular resistance. Pure CSA was dissolved in autologous blood and injected at doses of 0.5, 1, 5, and 10 mg. The infusion of 0.5 and 1 mg caused averaged renal perfusion pressure increases of 8 +/- 4 mmHg and 15 +/- 8 mmHg. Renal venous CSA levels averaged 32 +/- 3 and 49 +/- 9 nmol/l, respectively, at the end of injections. Infusion of 5 and 10 mg of CSA caused averaged renal perfusion pressure increases of 32 +/- 12 mmHg and 81 +/- 21 mmHg. Renal venous CSA levels at the end of injections averaged 142 +/- 30 and 382 +/- 82 nmol/l, respectively. A positive correlation was found between the changes in renal perfusion pressure and renal venous CSA levels. Blockade of alpha-adrenergic receptors, surgical renal sympathectomy, administration of thromboxane receptor antagonist, and endothelial-dependent vasodilation by acetylcholine infusion did not affect the renal vasoconstriction effect of CSA; renal response to CSA was prevented by blockade of the Ca channels with diltiazem, and the plasma endothelin concentration in renal venous blood increased significantly after injection of CSA. A dose-dependent increase in renal arterial resistance occurs with therapeutic blood levels of CSA. Renal vasoconstriction is induced by a local effect at the arterial wall, which is independent of neurogenic, adrenergic, and prostaglandin mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effect of direct injection of cyclosporine on the arterial vessels of the isolated hind limb in the dog.

Cyclosporine's toxic side effects are widely recognized as a cause of major morbidity. Peripheral vasoconstriction has been suggested as the pathophysiological mechanism for hypertension and renal failure caused by cyclosporine. To study vascular effects on peripheral arterial circulation, cyclosporine was injected into isolated hind limbs perfused at constant flow in the dog. Pure powder cyclosporine was dissolved in a 10% fat emulsion and infused directly into the arterial inflow of the perfused hind limb (n = 7) at a concentration of 5 mg/kg body weight. Reactivity of the vascular bed was first shown by an average decrease of 72 +/- 4 mmHg (95% confidence interval 63 to 81, P less than 0.01) in hind limb perfusion pressure after infusion of 5 mg nitroglycerin. Infusion of fat emulsion did not cause any significant changes. The infusion of cyclosporine caused an average increase of 29 +/- 5 mmHg (95% confidence interval 17 to 41, P less than 0.01) in hind limb perfusion pressure after 4 mins' infusion. After cyclosporine infusion, the vascular bed still responded to nitroglycerin by an average decrease of 56 +/- 5 mmHg (95% confidence interval 42 to 69, P less than 0.01) in perfusion pressure. Blockade of alpha-receptors with phentolamine in five dogs and ipsilateral lumbar sympathectomy in four prevented the increase in perfusion pressure following cyclosporine injection. In conclusion, cyclosporine injected at high doses causes a small vasoconstriction of the peripheral arterial circulation in the hind limb through stimulation of alpha-adrenergic receptors mediated by the sympathetic nervous system. Since the response is completely abolished by sympathectomy, it is probably caused by reflex activation. A direct effect of cyclosporine on the arterial vessel walls of the limb can therefore be excluded.

Animals↗
PubMed1991

[Effect of therapeutic doses of cyclosporine injected into the renal and femoral arteries in dogs].

Cyclosporine is the core component of all immunosuppressive protocols. Renal insufficiency and hypertension are the two major side effects of cyclosporine use. A vascular effect of cyclosporine could explain these complications. To study the effect of cyclosporine on vessel wall, a model of isolated renal and femoral artery perfusion was used in the dog. The injection of 0.5, 1, 5 and 10 mg of cyclosporine in the renal artery caused an average increase in renal perfusion pressure of 8 +/- 4, 15 +/- 8, 32 +/- 12 and 81 +/- 21 mmHg (p less than 0.05) respectively. Blockade of alpha-adrenergic receptors and renal sympathectomy did not modify the renal vascular response to cyclosporine. The injection of 1, 5, 10 and 20 mg of cyclosporine in the femoral artery caused an average increase in perfusion pressure of 4 +/- 2, 10 +/- 4, 9 +/- 2 and 20 +/- 8 mmHg (p less than 0.05) respectively. Blockade of alpha-adrenergic receptors and lumbar sympathectomy prevented the vasoconstrictive effect of cyclosporine on the femoral artery. Therefore, cyclosporine caused a significant increase in renal perfusion pressure and a modest vasoconstriction of the femoral artery. This effect appears to be related to an adrenergic mechanism only in the femoral circulation. We conclude that other studies are needed to define the mechanism responsible for the vasoconstrictive effect of cyclosporine.

Animals↗
PubMed1991

[Comparative, clinical and echocardiographic study of the Bex and De Vega annuloplasties].

A retrospective study of 27 cases compared the long term clinical and echocardiographic results of tricuspid valve annuloplasty by the Bex (15 patients) and the De Vega (12 patients) techniques. All patients were in NYHA Classes III or IV before surgery. There was associated mitral valve disease in 24 cases and mixed mitral and aortic valve disease in 3 patients requiring valve replacement. The follow-up period ranged from 3 to 106 months (average 48 +/- 4 months). All patients underwent clinical and color Doppler echocardiographic evaluation. There was symptomatic improvement after surgery as all patients recovered to NYHA Classes I or II. An echocardiographic classification was adopted to assess residual tricuspid regurgitation. The leak was judged to be significant when the surface area of the jet was greater than 5 cm2. Two thirds of patients (17/27) had no significant residual tricuspid regurgitation with the Bex or de Vega techniques of tricuspid annuloplasty according to this criterion. However, significant residual tricuspid regurgitation was observed in 37% of patients (10/27) even though they were all clinically improved. A comparison of the echocardiographic parameters including the severity of residual tricuspid regurgitation, the left and right atrial dimensions, the right ventricular dimensions and tricuspid valve pressure gradients did not show any significant long term difference between the Bex and the De Vega tricuspid annuloplasties.

Echocardiography, Doppler↗
PubMed1991

Accelerated coronary atherosclerosis after cardiac transplantation: major threat to long-term survival.

Accelerated coronary atherosclerosis (ACA) has been documented at autopsy and was noted at coronary angiography in seven patients, 11 to 48 months after cardiac transplantation. To delineate the importance of this problem, the risk factors and the therapeutic approaches in 7 patients who had ACA after heart transplantation were compared with those in 28 patients free of ACA at annual coronary angiography. Ischemic cardiomyopathy was the preoperative diagnosis in all but one patient in the ACA group. The age of the transplant recipients, total myocardial ischemic times and arterial blood pressures at follow-up were similar in both groups. Donor age averaged 31 +/- 3 years in the ACA group and 22 +/- 1 years in patients free of ACA. Preoperative cholesterol, triglyceride and high-density lipoprotein levels were lower in ACA-free patients and the low-density lipoprotein level was higher. At the last follow-up visit, serum lipid levels were similar in both groups. The incidence of acute rejection and of infection was slightly, but not significantly, higher in patients with ACA. The actuarial survival of ACA patients 4 years after transplantation was 30% +/- 20% compared with 100% for patients free of ACA (p less than 0.01). Actuarial rates of freedom from ACA and from death due to ACA were 73% +/- 11% and 81% +/- 11% respectively. Stepwise discriminant analysis showed that older donors and higher pretransplant triglyceride levels were independently related to the development of ACA after cardiac transplantation. In conclusion ACA remains an important cause of late death after heart transplantation. Although therapeutic measures are limited, prevention should focus on strict control of serum lipid levels after transplantation.

Adult↗
PubMed1990

Bromocriptine as an adjuvant to cyclosporine immunosuppression after heart transplantation.

Prolactin, a pituitary hormone, has been shown to have an active role in the regulation of the immune system. Prolactin receptors have been described on the membrane of lymphocyte cells, and competitive binding to these receptors by cyclosporine and circulating prolactin has been demonstrated. Experimental evidence suggests a synergistic effect of cyclosporine and bromocriptine, an inhibitor of pituitary release of prolactin, on immunosuppression. Between July 1986 and January 1988, 54 patients were randomly assigned to two groups of immunosuppression treatment. Thirty patients (group 1) were administered cyclosporine, azathioprine, and prednisone and 24 patients (group 2), a modified protocol aimed at decreasing the level of circulating prolactin by adding bromocriptine to the immunosuppression regimen. The two groups were similar in regard to age, preoperative diagnosis, and duration of follow-up. Minimal side effects related to bromocriptine were observed. The overall incidences of rejection and infection were similar, although actuarial analysis showed that freedom from these complications among patients treated with bromocriptine was significantly higher throughout the first 2 months after heart transplantation compared with that of patients in the control group. Other variables such as serum cyclosporine levels and lymphocyte counts were similar in both groups. In conclusion, suppression of circulating prolactin by bromocriptine appears to improve the immunosuppressive effect of cyclosporine, at least during the early postoperative period when the risk of rejection and infection is higher, and could be a promising avenue to successful hormonal manipulations of the immune process after organ transplantation.

Actuarial Analysis↗
PubMed1990

Double-blind comparison of pefloxacin and cefazolin as prophylaxis in elective cardiovascular surgery.

A total of 162 patients (134 males and 28 females) scheduled for coronary artery bypass grafting (144) or valve surgery (18) were randomly assigned to receive, under double-blind conditions, either pefloxacin 400 mg iv or cefazolin 1.0 g 30 min before the surgical incision and then post-operatively 12-hourly x 4 or 6-hourly x 8, respectively. Positive per- and post-operative cultures were seen in 27 patients (11 pefloxacin, 16 cefazolin) and 47 micro-organisms were isolated: 34 per-operatively (21 pefloxacin, 13 cefazolin) and 13 post-operatively (4 pefloxacin, 9 cefazolin). There were five failures of prophylaxis (2 pefloxacin, 3 cefazolin): two early (less than 5 days: 1 pefloxacin, 1 cefazolin) and three late (greater than or equal to 5 days, 1 pefloxacin, 2 cefazolin) divided into (i) one major primary failure in the cefazolin group (1 cefazolin resistant Staphylococcus epidermidis mediastinitis); (ii) two minor primary failures, one in each group (Gram-positive sternal incision abscesses) and (iii) two secondary failures (1 cefazolin resistant Enterobacter cloacae and Pseudomonas aeruginosa UTI in the cefazolin group and one culture negative pneumonia in the pefloxacin group). Tolerance to both antibiotics was excellent. In our sample of patients, the efficacy and safety of pefloxacin was not different from those of cefazolin in prophylaxis in cardiovascular surgery.

Aged↗
PubMed1990

Effects of flecainide and quinidine on human atrial action potentials. Role of rate-dependence and comparison with guinea pig, rabbit, and dog tissues.

Flecainide and other class IC antiarrhythmic drugs are effective in the prevention and termination of atrial fibrillation, but the mechanism of this action is unknown. To gain insights into potential cellular mechanisms, we evaluated the response of human atrial action potentials to equimolar therapeutic concentrations of flecainide and quinidine and compared this response to that of guinea pig, rabbit, and dog atria. Both compounds reduced Vmax more as activation rate increased, but flecainide was more potent than quinidine and had slower kinetics. The rate-dependence of Vmax reduction was similar for all species, but human tissue was more sensitive to the drugs tested. In contrast to changes in Vmax, drug-induced alterations in action potential duration showed opposite rate-dependence for the two drugs. Quinidine increased action potential duration to 95% repolarization (APD95) in human atria by 33 +/- 7% (mean +/- SD) at a cycle length of 1,000 msec, but this effect was reduced as cycle length decreased, to 12 +/- 4% (p less than 0.001) at a cycle length of 300 msec. Flecainide increased APD95 (by 6 +/- 3%) much less than quinidine at a cycle length of 1,000 msec, but its effect was increased by faster pacing, to 27 +/- 12% at a cycle length of 300 msec and 35 +/- 8% (p less than 0.001) at the shortest 1:1 cycle length. The rate-dependent response of APD to drugs was qualitatively similar but quantitatively different among species. Human tissue showed the greatest frequency-dependent drug effects on repolarization, followed by tissue from dogs and rabbits. Guinea pig atria showed the least (and statistically nonsignificant) rate-dependence of drug effect on APD. Drug-induced changes in refractoriness paralleled those in APD. We conclude that: 1) flecainide and quinidine both increase APD in human atrial tissue but with opposite rate-dependence, 2) the effects of flecainide to increase atrial APD and refractoriness are enhanced by the rapid rates typical of atrial fibrillation, and 3) animal tissues may differ importantly from human in both their sensitivity and rate-dependent response to antiarrhythmic drugs. The salutary response of atrial fibrillation to flecainide may be due to enhancement of drug action by the rapid atrial activation rates characteristic of this arrhythmia.

Action Potentials↗