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R Soyer

Publications and source records attributed to R Soyer.

At least 37 records · Page 2Linked to original sources
PubMed1997

Linear Bayesian inference for accelerated Weibull model.

In this paper, we present a Bayesian approach for inference from accelerated life tests when the underlying life model is Weibull. Our approach is based on the General Linear Models framework of West, Harrison and Migon (1985). We discuss inference for the model and show that computable results can be obtained using linear Bayesian methods. We illustrate the usefulness of our approach by applying it to some actual data from accelerated life tests.

Bayes Theorem↗
PubMed1997

[What myocardial protection to select for isolated aortic valve replacement? A clinical prospective study of 3 cases of cardioplegia].

Isolated stenosis of the aortic valve leads to left ventricular hypertrophy which makes myocardial protection difficult during cardiac, surgery and the choice of optimal cardioplegia remains controversial. The authors compared three protocols of cardioplegia in patients operated for isolated aortic stenosis with left ventricular hypertrophy. Sixty consecutive patients with these criteria were randomly attributed to one of the three following groups (20 in each group): cardioplegia with continuous warm blood; cardioplegia with intermittent cold blood with warm reperfusion; cardioplegia with intermittent cristalloid using SLF11 solution. The preoperative data was comparable in three groups. There were no deaths. Patients undergoing cardioplegia with warm blood came off cardio-pulmonary bypass more quickly (15 mn vs 21 mn for the other groups, p = 0.03). Cristalloid cardioplegia was associated with major acidosis in coronary sinus blood when the aorta was declamped (7.11 vs 7.38 for cardioplegia with cold blood and 7.39 for cardioplegia with warm blood, p < 0.0001) but with a low postoperative CPK-MB rise. Cardioplegia with cold blood induced higher CPK-MB liberation than the other forms of cardioplegia (at H-, 63 mcg/L vs 33 for warm blood and 45 for cristalloid cardioplegia, p = 0.0019). None of the protocols tested prevented myocardial lactate production at aortic declamping. Cardioplegia with warm blood offers therefore the best protection for hypertrophied myocardium during simple aortic valve replacement but it does not maintain strictly aerobic metabolism.

Aged↗
PubMed1997

[Coronary bypass in patients with severe left ventricular dysfunction (EF < or = 25%). Apropos of 111 patients].

One hundred and eleven patients with severe left ventricular dysfunction (EF < or = 25%) underwent coronary bypass surgery between January 1984 and December 1994. The selection criteria were based on the measurement of an EF < or = 25%, LVEDP and CI. All patients had angina and 83 had signs of pulmonary oedema or episodes of congestive failure. Patients with valvular disease, left ventricular aneurysms, reoperations, surgery for arrhythmias and prior angioplasty, were excluded. The coronary disease usually involved all three vessels. Seventeen patients had lesions of the left main stem associated with lesions of the right coronary artery. The average number of bypass grafts was 2.6 +/- 1.6 per patient. The average duration of aortic clamping was 60 +/- 19 minutes. Operative mortality (first month after surgery) was 10 patients (9%). The operative risk factors were: gender, stage of cardiac failure, emergency surgery, LVEDP > 23 mmHg (p < 0.05), CI < 21/min/m2 (p < 0.05). The mean follow-up period was 42 +/- months (3 lost to follow-up). Late mortality was 42 patients. The one year actuarial survival was 88 +/- 5.3%, 76 +/- 9% at 3 years, and 56 +/- 18% at 6 years. Long-term functional results were related to: preoperative stage of cardiac failure (NYHA stage IV) and the association of raised LVEDP and low CI. Surgical results remained satisfactory, however, and the surgical indication was justified in selected patients despite severe left ventricular dysfunction in cases usually with stable invalidating or unstable angina, in the knowledge that myocardial deterioration is progressive in the medium-term with a high incidence of cardiac failure.

Actuarial Analysis↗
PubMed1997

How to protect hypertrophied myocardium? A prospective clinical trial of three preservation techniques.

Protection of the hypertrophied myocardium during heart surgery is still a controversial matter. We prospectively studied 3 currently available preservation techniques in 60 patients operated on for isolated aortic stenosis. Patients were randomly assigned to one of the following groups: CWB: continuous warm blood cardioplegia ICB: intermittent cold blood with warm blood controlled reperfusion Cryst: intermittent cold crystalloid cardioplegia (SLF11, Biosédra Laboratory, Vernon, France). All groups were matched for age, ejection fraction, NYHA class, aortic valve surface, and operative risk score. There were no deaths. No statistically significant difference was found among the groups in terms of ventilatory support time, ICU stay time, hospitalization or atrial fibrillation occurrence. Blood gases in the coronary sinus at the time of clamp release showed deep acidosis with crystalloid cardioplegia (pH = 7.11 vs 7.39 for CWB and 7.38 for UCB, p < 0.0001) associated with a higher lactate production than in the other groups (1.3 mmol vs 0.5 for CWB and 0.58 for ICB, p < 0.0001). Acidosis was corrected at the end of bypass with no significant differences among groups. CK-MB samples were taken on arrival in ICU, then 6 and 24 hours later. These samples showed much higher levels with cold blood (H6: 70 mcg/l vs 33 for CWB and 45 for Cryst, p = 0.0019). Although the 3 types of cardioplegia may be safely used for isolated aortic stenosis surgery, continuous warm blood cardioplegia appears to be the best choice.

Aged↗
PubMed1997

[Primary treatment of left coronary artery diseases by percutaneous implantation of stents].

Left main coronary artery (LM) stenting has only been reported in bail-out situations or absolute contraindications so surgery. The authors report the immediate and midterm results of primary Palmaz-Schatz stent implantation in two young patients without contraindication to surgery. The first patient, 58 year-old, was admitted for unstable angina in October 1994. Coronary angiography showed an isolated severe ostial lesion of the LM. After conferring with the surgical team which remained on stand-by, angioplasty and stent implantation were performed with excellent results, no complications and no restenosis on angiographic controls at 3 and 12 months. The patient remained asymptomatic 24 months later. The second patient, 38 year-old, was admitted in June 1995 for unstable angina, and coronary angiography showed a severe isolated stenosis in the middle of a long and wide LM. Primary coronary stenting was also performed with excellent results, no complication and no restenosis on angiographic controls at 4 and 8 months. This patient was still asymptomatic 16 months after stenting. These excellent immediate and medium-term results are encouraging and suggest that this form of treatment might be extended to patients with an isolated whether primary LM stent implantation could become a suitable alternative to surgery in the future.

Adult↗
PubMed1996

Mitral valve reconstruction: long-term results of 120 cases.

Between January 1977 and December 1992, 120 patients underwent mitral valve reconstruction for pure mitral valve regurgitation (n = 88), or associated with mitral stenosis (n = 32). The mean age was 57.6 years. Some 89 patients were in New York Heart Association (NYHA) class III and IV; 61% were in atrial fibrillation. Four mechanisms of mitral regurgitation were assessed: dilatation of the annulus (group I: n = 10); increased amplitude of valve motion (group II: n = 62); restriction of valve motion (group III: n = 23), and mixed lesions (group IV: n = 25). Mitral valve repair was carried out using techniques described by Carpentier. Ring annuloplasty was performed in all patients. There were two operative deaths, and six late deaths. Mean patient follow-up was 41 (range 2-142) months. The actuarial survival rate, excluding hospital deaths, was 91.7% at 5 years and 89.1% at 8 years. Actuarial freedom from reoperation at 8 years was 95(2)%. Freedom from all thromboembolic complications was 89.1% at 8 years. Most survivors had improved to NYHA class I or II and postoperative Doppler echocardiography revealed satisfactory mitral valve competence in 83 patients. Mitral valve reconstruction for mitral regurgitation using Carpentier techniques provides excellent long-term functional results and should be considered as the procedure of choice in patients referred for mitral regurgitation.

Adolescent↗
PubMed1996

Aortic valve replacement after aortic valvuloplasty for calcified aortic stenosis.

OBJECTIVE: This study concerns patients who underwent one or several aortic balloon valvuloplasties at our institution and subsequently required cardiac surgery, either on an emergency basis after aortic valvuloplasty or due to the development of aortic stenosis. METHODS: Between February 1987 and December 1993, 137 patients (73 male, 64 female, mean age 72 +/- 9 years) underwent aortic valve replacement for calcified aortic stenosis after several percutaneous balloon aortic valvuloplasties. Thirty-one patients were in NYHA stage II, 70 in stage III and 36 in stage IV. Seventy patients had angina (23 stage I or II, 47 stage III or IV) and 24 patients presented syncope or lipothymia. Twenty-three percent had at least two of these three symptoms. The indications for balloon dilatation were non-definitive surgical contraindication or high surgical risk (73), personal choice (49), refusal of surgery (9) and emergency (5:2 massive aortic regurgitation, 1 left ventricle perforation, 1 cardiogenic shock, 1 endocarditis in cardiogenic shock). Seven patients received preoperative aortic valvuloplasty due to a very high operative risk. The average time between dilatation and surgery was 472 days and there was clinical improvement for an average period of 261 days. The aortic valve replacements consisted of 58 mechanical prostheses and 79 xenografts with 22 concomitant procedures. RESULTS: Operative mortality was eight patients (5.8%). During the follow-up (17.4 +/- 9.2 months), four patients died (3.6%), 91.2% of the patients were in class I and II and 95% were without angina. The actuarial survival rate was 90.5 +/- 6.6% including hospital mortality. CONCLUSIONS: Both our experience and the literature show that balloon aortic valvuloplasty is followed by an immediate improvement in hemodynamic status with a decrease in valve gradient and an increase in valve area. However, the hemodynamic benefit is typically short-lived with a very high restenosis rate. Balloon aortic valvuloplasty is not an alternative to aortic valve replacement, which remains the best treatment for calcified aortic stenosis; the benefits and long-term results of aortic valve replacement are well established, even in the elderly.

Adult↗
PubMed1996

[Value of dobutamine echocardiography in the detection of coronary disease in heart transplant patient. Groupe de Recherche VACOMED].

The value of Dobutamine stress echocardiography in the detection of coronary artery disease in heart transplant patients was studied in 64 patients at control coronary angiography 39 +/- 14 months after transplantation. Dobutamine was infused at progressively increasing doses (5 to 40 micrograms/kg/min) at 5 minute intervals, in order to reach 85% of the theoretical maximal heart rate or an ischaemic event. Echocardiography was analysed in the 4 standard views which were digitised allowing calculation of a regional wall motion score under basal conditions and at peak dosage in 16 left ventricular segments. Coronary angiography identified three groups: group I: 29 patients with normal coronary arteries; group II: 17 patients with non-significant coronary disease (diffuse or localised stenosis < 50%); group III: 9 patients with significant (> 50%) coronary disease. Dobutamine stress echocardiography showed regional wall motion abnormalities in 2/29 patients in group I, 13/17 patients in group II and all patients in group III (global sensitivity: 85%; specificity: 97%). The contractility score was significantly higher under basal conditions in group III (1.45 +/- 0.54) than in group I (1) and group II (1.17 +/- 0.23). At peak dose, the contractility score was unchanged in group I and increased significantly (p < 0.01) in the other two groups. The authors conclude that Dobutamine echocardiography is a reliable, non-invasive method of detecting coronary disease in cardiac transplant patients, and is particularly valuable for demonstrating myocardial ischaemia related to coronary lesions judged to be not significant at coronary angiography.

Adult↗
PubMed1995

Standard orthotopic heart transplantation versus total orthotopic heart transplantation. A transesophageal echocardiography study of the incidence of left atrial thrombosis.

BACKGROUND: After standard orthotopic heart transplantation (Sd HT), the enlarged resultant atria may promote atrial thrombosis. The purpose of this study was to compare the incidence of spontaneous echo contrast and left atrial thrombosis after Sd HT and total orthotopic (Tot HT) heart transplantation. METHODS AND RESULTS: Transesophageal echocardiography (TEE) was performed in 75 patients with Sd HT and in 20 patients with Tot HT. Despite the use of antiplatelet therapy, an acute arterial embolism occurred in 11 (15%) of the 75 patients with Sd HT but in none of the 20 Tot HT patients. All patients were in sinus rhythm. Left ventricular ejection fraction was similar in Sd HT and Tot HT patients. Left atrial diameter was smaller in Tot HT patients than in Sd HT patients (41 +/- 4 versus 58 +/- 6 mm, P < .001). In Sd HT patients, spontaneous echo contrast was present in 43 patients (57%) and was associated with left atrial thrombus in 20 patients (on the left atrial appendage in 12 patients, on the posterior wall in 6, and on the suture in 2). No thrombus was detected by transthoracic echocardiography; all thrombi were detected by TEE. On the other hand, no left atrial thrombus was observed in Tot HT patients, and only 1 patient had spontaneous echo contrast. Of the 11 Sd HT patients who experienced an arterial embolism, 5 had both spontaneous echo contrast and left atrial thrombus and 5 had only spontaneous echo contrast. CONCLUSIONS: This study demonstrates a high rate of left atrial thrombus after Sd HT and emphasizes the role of TEE in the follow-up of these patients. The therapeutic implications are the need for a preventive anticoagulant therapy in the high-risk population receiving Sd HT diagnosed with TEE and the consideration of Tot HT as a better surgical approach as far as thrombotic complications are concerned.

Adult↗
PubMed1995

Dobutamine stress echocardiography in orthotopic heart transplant recipients. VACOMED Research Group.

OBJECTIVES: This study sought to determine whether dobutamine stress echocardiography could accurately identify coronary artery disease after heart transplantation. BACKGROUND: After heart transplantation, coronary artery disease is related to either diffuse concentric intimal thickening or focal stenosis and may be underdiagnosed by coronary angiography. METHODS: We enrolled 41 patients, a mean (+/- SD) of 40 +/- 20 months after heart transplantation, at the time of their routine control coronary angiogram. Three patients were excluded because of poor echogenicity on the angiogram and one because of ventricular premature beats. Standard echocardiographic views were acquired at baseline and at incremental dobutamine infusion levels (from 5 to a maximal dose of 40 micrograms/kg body weight per min at 3-min intervals). Regional wall motion score was calculated from a 16-segment model, and each segment was graded from 1 (normal) to 4 (dyskinesia). Coronary angiography was performed 24 h after dobutamine stress echocardiography, and angiograms were analyzed in blinded manner. RESULTS: Twenty-three (62%) of 37 patients had normal coronary angiographic findings. Dobutamine stress echocardiography showed abnormalities in only 2 of 23 patients. Fourteen patients (38%) had abnormal angiographic findings, seven of whom had stenoses > 50%. Dobutamine stress echocardiography correctly identified the corresponding hypoperfused segments in these seven patients. More of interest were the other seven patients, of whom three had angiographic nonsignificant stenoses (< 50%), and four had minor diffuse coronary irregularities. Dobutamine stress echocardiography showed hypokinesia in five of these seven patients despite nonsignificant lesions at coronary angiography. The respective overall sensitivity and specificity of dobutamine stress echocardiography were 86% and 91%. At follow-up, 2 of the 37 patients had an acute myocardial infarction. Both had abnormal findings on dobutamine stress echocardiography: One had normal coronary angiographic results, and one had significant coronary lesions. CONCLUSIONS: Dobutamine stress echocardiography is a useful technique for the diagnosis of coronary artery disease after heart transplantation. These preliminary results indicate that dobutamine stress echocardiography may have a predictive value for further ischemic events in heart transplant recipients.

Cardiac Catheterization↗
PubMed1995

High incidence of left atrial thrombus detected by transoesophageal echocardiography in heart transplant recipients.

The aim of the study was the detection of spontaneous echo contrast (SEC) and left atrial thrombus by transoesophageal echocardiography (TEE) in patients who had undergone orthotopic heart transplantation. TEE was prospectively performed in 64 heart transplant recipients (53 males, 11 females, mean age 51 years). Since surgery (mean time: 31 months), all heart transplant recipients had received either aspirin (39), or dipyridamole (22), or both (3). Despite the antiplatelet treatment, an acute arterial embolism (two strokes, one popliteal and one mesenteric ischaemia) occurred in four patients who subsequently received an oral anticoagulant therapy. TEE was performed with a biplane high-frequency transducer after lidocaine pharyngeal anaesthesia, midazolam intravenous injection and antibiotic prophylaxis. Mean ejection fraction was 63 +/- 10%. None had evidence of rejection at endomyocardial biopsy performed on the same day as TEE and analysed in a blinded fashion. All were in sinus rhythm. Left atrial SEC was found in 35 patients (55%) and was associated with left atrial thrombus in 18 patients (28%). These thrombi were localized in the donor left atrial appendage in 10 cases, on the posterior wall of the left atrium in six cases, on the donor part of inter-atrial septum in one case and on the suture line in one case. They were not detected by transthoracic echocardiography (TTE). When compared with patients without thrombus, no difference was found concerning left atrial size, left ventricular ejection fraction, pulmonary artery pressure and number of previous episodes of rejection. However, cardiac index was significantly lower in patients with left atrial thrombus.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Function, Left↗
PubMed1995

Balloon aortic valvuloplasty in elderly patients at high risk for surgery, or inoperable. Immediate and mid-term results.

Although aortic valve replacement is undoubtedly the treatment of choice for aortic valve stenosis, balloon aortic valvuloplasty may represent the only possible treatment for some frail elderly patients who may have additional medical problems. We evaluated immediate and 1-year results of balloon aortic valvuloplasty in 86 patients > or = 80 years with severe aortic stenosis. Mean age was 84 +/- 3 years. Forty-four % were 85 years or older. Mean gradient decreased from 68 to 26 mm Hg and valve area increased from 0.53 to 0.96 cm2 (P<0.05). There were two per-procedural deaths. No local vascular complication was observed. During the follow-up (13 +/- 9 months), 27 patients died, four had repeat balloon aortic valvuloplasty and eight underwent aortic valve replacement. Persistent clinical improvement was observed in 78% of the surviving patients. One-year actuarial survival rate was 73%. Balloon aortic valvuloplasty appears to be a safe and valuable technique in cases where surgery cannot be performed or carries a very high risk.

Aged↗
PubMed1995

[Right atrial thrombosis; an unusual late complication of the Fontan procedure. Apropos of a case].

The authors report the case of a large right atrial thrombosis causing acute cardiac failure in an 18 year old patient with tricuspid atresia who had undergone 3 operations: Waterston shunt at 2 months of age, Fontan procedure at 3 years of age with reoperation at 13 years of age. The diagnosis was made at echocardiography and angiography. Surgical management comprised ablation of the thrombus and a tunneling of the right atrium between the inferior vena cava and the atriopulmonary conduit. The immediate postoperative course was complicated by a slowly regressive neurological deficit. The medium-term outcome (one year) is satisfactory with antiarrhythmic and anticoagulant therapy. A review of the literature showed that these thromboses are not exceptional in the early postoperative period for a variety of reasons. Secondary thrombosis is often related to arrhythmias, thus requiring clinical, electrocardiographic and echocardiographic follow-up of these patients and the prescription of antiarrhythmic and anticoagulant therapy. The diagnostic methods are discussed. Echocardiography may be sufficiently explicit to make potentially risky angiography unnecessary.

Adolescent↗
PubMed1994

Surgical treatment of infected composite graft after replacement of ascending aorta.

Infection of a composite graft is a serious complication. However, reports of such cases are rare even in large series. We report our experience with 4 patients in whom infection of a composite graft developed with pseudoaneurysm formation. Two of the patients had Marfan's syndrome and were treated by Bentall procedure and 2 were treated by Cabrol technique for non-Marfan cystic medial necrosis. Staphylococcus epidermidis was detected in 2 patients and Enterococcus in 1. Reoperation was carried out between 1 and 32 months after the first intervention. One patient died of cerebral embolism and 3 remained free of infection 11 to 82 months later. These cases and guidelines for managing abdominal and peripheral vascular prosthetic infection indicate the need for prompt reintervention when infection is suspected from chronic sepsis, septicemia, positive blood cultures, fistula, anastomotic leak, hemolysis, embolism, graft deformity, or false aneurysm. When the organism is isolated, appropriate antibiotic therapy should be administered. All prosthetic material should be removed and all adjacent infected or necrotic tissue excised. Local antiseptic irrigation may be helpful. Dead space around the prosthesis should be filled with well-vascularized transposed pedicled flaps. Antibiotic therapy should be intravenously administered for at least 6 weeks.

Adult↗