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Biomedical subjects

D Loisance

Publications and source records attributed to D Loisance.

At least 91 records · Page 5Linked to original sources
PubMed1993

Positron emission tomography with 11C CGP-12177 to assess beta-adrenergic receptor concentration in idiopathic dilated cardiomyopathy.

BACKGROUND: Positron emission tomography (PET) with 11C-labeled CGP-12177 (CGP) has been shown to have the potential to noninvasively measure beta-adrenergic receptor concentration in dog heart. The present study was undertaken to evaluate the clinical value of this technique. METHODS AND RESULTS: Eight normal subjects and 10 patients with heart failure related to an idiopathic cardiomyopathy were studied. Estimation of beta-receptor concentration was based on a graphic method applied on myocardial PET time-concentration curves obtained after an intravenous injection of 11C-CGP followed 30 minutes later by a coinjection of labeled and unlabeled CGP. The clinical tolerance of these injections was good. Left ventricular concentration of beta-receptors was decreased in patients compared with controls (3.12 +/- 0.51 versus 6.60 +/- 1.18 pmol/mL, respectively; p < 0.001). This 53% decrease agrees with previous in vitro data. In eight of the 10 patients, the beta-receptor concentration obtained from PET was compared with the beta-receptor density determined on left ventricular endomyocardial biopsy samples by in vitro binding technique using 3H-CGP-12177. Results obtained with both techniques were correlated (r = 0.79, p = 0.019). Moreover, decreased beta-receptor concentration correlated with the beta-contractile responsiveness to intracoronary dobutamine infusion (r = 0.83, p = 0.003), indicating a direct link between changes in the receptor number and its biological function. CONCLUSIONS: PET appears to be a safe and reliable method of assessing in vivo changes in the number of left ventricular beta-adrenergic receptor sites of patients with idiopathic cardiomyopathy.

Adrenergic beta-Antagonists↗
PubMed1993

[Aprotinin in cardiac surgery in patients with platelet anti-aggregant treatment].

A large number of coronary patients referred for coronary bypass surgery receive platelet anti-aggregant therapy which has the disadvantage of increasing per and postoperative haemorrhage. The aim of this study was to assess the effects of aprotinin in 60 patients under platelet antiaggregant therapy (aspirin 250 mg/day) for over 30 days before surgery for coronary bypass grafting. The clinical (age, weight, diagnosis, bypass time, number of grafts) and biological features (preoperative haemoglobin concentration, platelet count and fibrinogen levels) were identical in a group treated by aprotinin (Group A, n = 30) and a control group (Group B, n = 30). The aprotinin treatment protocol was an intravenous injection of 2 million KIU (kallikrein inhibitory units) before starting the cardiopulmonary bypass and 2 million KIU in the filling liquid of the bypass circuit. A significant reduction in blood loss was observed in Group A with respect to Group B (370 +/- 154 ml versus 651 +/- 323 ml at day 1, p < 0.01). The haemoglobin concentration was higher in Group A than in Group B (11.9 +/- 1.6 g/100 ml versus 10.3 +/- 1.4 g/100 ml, p < 0.001) and fewer patients required blood transfusion (Group A: 16% versus Group B: 43%, p = 0.04). In conclusion, high doses of aprotinin given to patients on aspirin therapy undergoing coronary bypass surgery, significantly reduce postoperative blood loss and the number of patients transfused.

Aged↗
PubMed1993

[Coronary reoperations: indications and results].

The aim of this study was to assess the results of coronary reoperations and to determine the indications. Between January 1972 and December 1990, 166 coronary reoperations were performed in 161 patients (5 patients were operated three times). The interval between the first and second operation was 93 +/- 46 months. The interval between recurrence of symptoms and reoperation was 27 +/- 40 months. Recurrence of symptoms was related to isolated problems with the bypass grafts in 23% of cases, to an aggravation of the coronary disease without problems with the bypass grafts in 17% of cases and to an association of the two conditions in 60% of cases. Mortality in the first 30 postoperative days was 7.8% (13/161). The predictive factors of mortality were age over 70 years and an interval between recurrence of symptoms and reoperation of over 12 months. The causes of death were myocardial infarction (n = 5), left ventricular failure (n = 4), sudden death (n = 3), and arrhythmias (n = 1). The average follow-up period of survivors (n = 134) was 40 +/- 32 months. Four patients have been transplanted. Seven patients died secondarily. The cause of death was cardiac in 4 cases and non-cardiac in 3 cases. The actuarial 5 year and 10 year survival rates were 85 +/- 3%. Actuarial absence of myocardial infarction, angina, Class III-IV cardiac failure and transplantation was 87 +/- 4% at 5 years and 69 +/- 10% at 10 years. These figures show that coronary reoperation gives good functional results and long-term survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1993

[Preservation of the aortic valve in acute dissection of the ascending aorta].

The aim of this study was to evaluate the status of the native aortic valve in patients operated for acute dissection of the ascending. aorta (ADAA). Between November 1972 and November 1991, 93 patients were operated for ADAA. There were 76 men and 17 women (average age 54 +/- 12 years). The aortic valve was reserved in 80 cases (86%). In 13 patients (14%) aortic valve replacement was associated with replacement of the ascending aorta. The early mortality was 29% (27/93). The global actuarial survival rates at 5, 10 and 15 years were 60.2 +/- 5.2%, 49.7 +/- 6.1% and 26.9 +/- 9.9% respectively. Fifty patients (94%) in whom the native aortic valve was preserved were followed up. Nine patients (18%) died and average of 97 +/- 46 months after surgery. The causes of death were aortic rupture or extension of the dissection (N = 4), ischemic cardiac failure (N = 2), renal failure (N = 1), cerebrovascular accident (N = 1) and sudden death (N = 1). Forty one patients underwent transthoracic echocardiography. Seven patients developed severe aortic regurgitation, 6 of whom had to be reoperated for aortic valve replacement. Echocardiography showed absence of of minimal aortic regurgitation in 22 cases and mild aortic regurgitation with normal left ventricular function in 12 cases (in 2 cases, aortic valve replacement was associated with surgical treatment of another valvular lesion or of coronary artery disease). Therefore, aortic valve replacement was performed in 8 patients 61.5 +/- 51.2 months after the initial operation.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1993

Cost-effectiveness in patients awaiting transplantation receiving intravenous inotropic support.

Cost-effectiveness, assessed in terms of cost/survivor and cost/additional day of survival, has been evaluated in two groups of patients awaiting cardiac transplantation: in six treated by mechanical support (mechanical bridge) and in 31 treated successfully by the addition of intravenous enoximone to previous existing inotropic support (pharmacological bridge). The mean cost per patient was $45,843, ranging from $38,326 in patients receiving pharmacological support to $84,683 in patients receiving mechanical support. The cost per patient transplanted after pharmacological support was $50,745. The mean cost per survivor at 1 year was $210,000 for all patients, ranging from $192,455 with pharmacological support to $254,000 with mechanical support. At 1 month, the cost per additional day of survival was higher (by 228%) in the mechanical support group than in the pharmacological support group.

Cost-Benefit Analysis↗
PubMed1993

[Simultaneous heart and kidney transplantation using the same donor].

From 1988 to 1991, five cases of combined heart and kidney transplantation using the same donor have been achieved at our institution. All patients were males, 58 +/- 6 (46 to 64). The cardiac condition leading to the cardiac replacement was a dilated cardiomyopathy in one case, end-stage ischemic disease in 3, and failure of a previous cardiac transplantation in one. The renal condition claiming for a graft was a Glomerular nephritis in one, a polycystic disease in 3, and renal failure due to CyA toxicity in one; chronic hemodialysis was mandatory in all patients but one. There were no hospital deaths. The five patients are current survivors, the mean follow-up being 22 +/- 10 months (2-50 months). Five rejection episodes occurred in three patients; two patients have never demonstrated any cardiac rejection. All but one recovered a normal renal function as soon as the 7 th post operative day; only one episode of renal rejection has been detected, easily reversed by corticoids. No simultaneity was ever observed between cardiac and renal rejection episodes. Thus, the detection of rejection must be carried out separately for each graft organ. In four patients, cineangiograms of the coronary vessels were done respectively 12, 30 and 50 months post operatively and revealed a normal coronary bed. Thus, combined heart and kidney transplantation seems to be a realistic approach in properly selected patients in whom cardiac and renal failures cannot be treated by more conventional procedures.

Heart Transplantation↗
PubMed1992

[Discordant heart xenografts. Experimental study in pigs conditioned by total lymphoid irradiation and cyclosporine A].

The use of discordant xenografts may solve some of donor shortage problems. The beneficial effects of treatment with total lymphoid irradiation (TLI) and classical drugs on this discordant model of transplantation rejection was evaluated. Twenty-four lamb hearts were transplanted heterotopically in the abdomen of 24 pigs. Group I received no treatment (control). Group II received continuous intravenous medical treatment cyclosporin A (CyA) (5 mg/kg) and azathioprine (3 mg/kg) 3 days prior to transplantation. Group III received the same medical treatment and simultaneously 12 grays of irradiation in 5 equal fractions with a high rate (100 cGy/min) or a low rate (1.6 cGy/min) prior to transplantation. Group IV also received 12 grays in 5 fractions at a high rate followed by the medical treatment started 5 days after TLI and continued until the day of transplantation. Antibody and serum cyclosporine levels were monitored. Histology specimen were analyzed at the end of the experiment. Mean GST (graft survival time) in group I and II was 140 +/- 35 min and 117 +/- 27.4 min respectively. The histological features of these hearts suggested acute humoral rejection (hemorrhage, thrombosis, and edema) without cellular infiltration. In group III, one heart functioned 4.5 days with pathological features of cellular rejection and a second animal died at 6 hours with a functioning graft with no evidence of an acute rejection. Both had been treated with the low rate TLI protocol (1.6 cGy/min). The mean GST in this group was 1080 +/- 794 min. In Group IV, one graft functioned for 6.5 days and another for 3.25 days. Mean GST was significantly increased in this group to 4800 +/- 2647 min (p < 0.05). A cellular infiltration was seen in this two grafts. The remaining graft was rejected in 6 hours with histological lesions typical of acute humoral rejection. Antibodies levels at the time of transplantation were lowest (40%) in group IV and in the low rate irradiation group. The ability of TLI to induce tolerance and to prolong survival in a discordant xenograft model depends upon cumulative dose, rate of irradiation, delay between TLI and graft placement, and combined treatment with immunosuppressive drugs. A high rate of TLI and graft placement is delayed. Low rates of irradiation may be beneficial when there is a very short period between treatment and transplantation. These findings highlight the potential usefulness of TLI in combination with immunosuppressive drug therapy when antibody-mediated rejection occurs, such as with xenograft and in sensitized patient.

Animals↗
PubMed1992

Effects of time and previous acute rejection episodes on coronary vascular reserve in human heart transplant recipients.

OBJECTIVES: This study examined whether previous rejection episodes may have deleterious effects on coronary vascular reserve of heart transplant recipients months after transplantation. BACKGROUND: Coronary reserve has been demonstrated to be within the normal range in long-term transplant patients without previous episodes of rejection. Conversely, acute rejection is associated with a dramatic reduction of coronary reserve, which is rapidly restored after therapy. METHODS: Coronary flow velocity was measured by intracoronary Doppler catheter before and after a maximally vasodilating dose of intracoronary papaverine in 16 control subjects and in 59 transplant patients classified into three groups with respect to time after transplantation: 1 to 6 months (group 1, n = 17), 7 to 18 months (group 2, n = 22) and > 18 months (group 3, n = 20). Coronary vascular reserve was evaluated through peak/rest coronary flow velocity ratio and minimal coronary vascular resistance index. All patients had normal findings on left ventricular angiography and coronary arteriography and a normal left ventricular mass. RESULTS: Arterial pressure was normal in all groups. Heart rate in the three groups of transplant patients, mean aortic pressure in groups 1 and 2, left ventricular systolic pressure in group 2 and rate-pressure product in groups 1 and 2 were higher than in control subjects. Average number of rejection episodes per patient was similar in the three groups of patients (group 1, 2.4 +/- 1.4; group 2, 2.5 +/- 1.9, and group 3, 2.1 +/- 1.3). Results showed no difference between each group of transplant patients and control subjects for peak/rest coronary flow velocity ratio (control subjects, 5.2 +/- 0.8; group 1, 5.3 +/- 1.5; group 2, 4.9 +/- 1.2, and group 3, 4.4 +/- 1.6) and for minimal coronary vascular resistance index (control subjects, 0.18 +/- 0.03; group 1, 0.18 +/- 0.04; group 2, 0.20 +/- 0.06, group 3, 0.23 +/- 0.11). In addition, patients with zero or one rejection episode had similar values of peak/rest coronary flow velocity ratio and minimal coronary vascular resistance index (4.3 +/- 1.3 and 0.23 +/- 0.10, respectively, n = 22) as did those with one or two rejection episodes (5.1 +/- 1.5 and 0.19 +/- 0.07, respectively, n = 24), and those with four or more episodes (5.2 +/- 1.4 and 0.19 +/- 0.05, respectively, n = 13). CONCLUSIONS: This study showed that coronary vascular reserve remains within normal range and is independent from the number of previous episodes of rejection until late after transplantation in human heart transplant patients with angiographically normal coronary arteries.

Analysis of Variance↗
PubMed1992

Beta-adrenergic contractile reserve as a predictor of clinical outcome in patients with idiopathic dilated cardiomyopathy.

To examine the ability of beta-adrenergic contractile reserve assessment to predict the outcome of patients with heart failure, a prospective study was undertaken in 35 patients with idiopathic dilated cardiomyopathy and radionuclide ejection fraction below 40%. During right- and left-sided catheterization, right atrial and left ventricular (LV) pressures, peak positive LV dp/dt, cardiac index, and plasma norepinephrine and epinephrine concentrations were measured at baseline. After a left main intracoronary infusion of dobutamine (25 to 200 micrograms.min-1), beta-adrenergic contractile responsiveness was assessed as the net increase in peak positive LV dp/dt (delta LV dp/dt). After the initial examination, patients were treated with diuretics, digitalis, and angiotensin converting enzyme inhibitors and then followed-up. After a mean follow-up period of 13 +/- 7 months, two groups of patients were distinguished: those who responded to medical therapy (group A, n = 26) and those with clinical deterioration (group B, n = 9) leading to death (n = 4) or heart transplantation (n = 5). Initial peak positive LV dp/dt, LV end-diastolic pressure, cardiac index, and LV ejection fraction were better in group A than in group B (p less than 0.001). Initial plasma norepinephrine and epinephrine concentrations were significantly higher and delta LV dp/dt was lower in group B than in group A (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Myocardial beta-adrenergic desensitization and neuronal norepinephrine uptake function in idiopathic dilated cardiomyopathy.

Desensitization of myocardial beta-adrenergic receptors may result both from an impairment of the norepinephrine (NE) neuronal uptake function and from an increase in circulating NE concentrations. The respective role of these two mechanisms of desensitization was examined in 18 patients with congestive heart failure related to an idiopathic dilated cardiomyopathy. The neuronal NE uptake system was evaluated by [123I]metaiodobenzylguanidine (MIBG) scintigraphy. The desensitization level of beta-adrenoceptors was assessed as the net increase in peak positive left ventricular (LV) dP/dt during intracoronary dobutamine infusion. Arterial NE concentrations were determined at baseline. To obtain control values, we performed MIBG scintigraphy and determined baseline NE concentration in 12 normal subjects. Cardiac MIBG uptake was significantly decreased in patients as compared with controls. This decrease was related to the severity of the disease based on hemodynamic indexes. The inotropic response to intracoronary dobutamine infusion of heart failure patients correlated with both increased baseline NE concentration and diminished cardiac MIBG uptake (r = -0.63, p less than 0.01 and r = 0.73, p less than 0.001, respectively). These findings indicate that the desensitization process is related both to impaired neuronal NE uptake function and increased circulating NE concentrations. Moreover, a subset of 11 patients with moderate heart failure was identified who had diminished cardiac MIBG uptake but normal circulating NE concentrations. This suggests that impairment of the NE uptake function is an early mechanism of desensitization in idiopathic cardiomyopathy. Cardiac MIBG imaging may be a noninvasive means to assess severity of heart failure patients and may also be used to evaluate therapy effects on myocardial alterations of the adrenergic pathway.

3-Iodobenzylguanidine↗
PubMed1992

[Artificial hearts. The experience of Henri Mondor University Hospital].

Results obtained with 52 patients referred for urgent heart transplantation or when transplantation was impossible because no graft, mechanical assistance or circulatory support were available, are reported. These suggest that the protocol used to select the indications of assistance and transplantation, based on the response to the introduction of enoximone into the medical treatment, allows reconciling the patients' interest-their survival-with the community's interest-i.e. the control of the costs of implemented treatments.

Adult↗
PubMed1992

Mode of failure of the Mitroflow pericardial valve.

A consecutive series of 188 Mitroflow pericardial bioprostheses were inserted in 166 patients between 1st January 1983 and 31st December 1985. Twenty-two valves had to be removed from 16 patients after a mean follow up period of 78 months (range 58-92 months) for aortic, 73 months (65-79 months) for mitral and 78 months (48-103 months) for double valve replacements. All but one reoperations for primary tissue failure were carried out as elective surgical procedures. The most important cause of failure was collagen degeneration, seen in all explanted valves. The areas of degeneration were the major sites of origin of calcification, which was seen in 11 valves (50%). Ten valves (45%) showed features suggestive of lipid infiltration, extensive fatty acid deposition being identified in one and a typical atheromatous reaction in another. In contrast to the Ionescu-Shiley valve, the mode of failure was tear originating at the top of the commissure, associated with major structural changes in the tissue. Excessive pannus ingrowth was observed in 11 valves (50%). The universal presence of tissue degeneration in the glutaraldehyde treated pericardial leaflets of the Mitroflow bioprostheses explanted and examined in this study questions the adequacy of the methods employed in the harvesting and/or processing and/or preservation of this valve. We have, therefore, discontinued using the Mitroflow bioprosthesis. However, the slow deterioration of the Mitroflow bioprosthesis permits elective reoperation; preventive removal of functioning valves is therefore not indicated.

Adult↗
PubMed1992

[Emergency aorto-coronary bypass after myocardial infarction].

During a recent three-year period, 37 patients had an emergent aortocoronary bypass (ACB) after evolutive acute myocardial infarction. The patients are divided up into two groups: group I includes 12 patients who were operated after the failure of early thrombolysis; group II includes 25 patients operated after the failure of revascularization through percutaneous angioplasty. In group I, all patients survived and 9 had no postoperative complications. In group II, the outcome was favorable for 16 patients. Long-lasting postoperative inotropic support was required for nine patients. Two patients died early. In all patients of the study, surgery failed to prevent myocardial necrosis but there was no recurrence of angina nor major left ventricular malfunction in the long term. This work suggests that early surgery after acute myocardial infarction may be a rescue procedure, with low risks and good long-term results.

Aged↗
PubMed1992

[Synergic effect of Dextran 70 at 32% and an antibiotic in the prevention of peritoneal adhesions. Experimental study in rats].

In an experimental study we evaluate the anti-adherential effect of four different solutions: physiological serum, Chloramphenicol, Dextran 70 (32%) and the association of these last two solutions. Synergic effect is shown when using an antibiotic (Chloramphenicol) with a non-bactericid solution (Dextran). Comparing our results with current literature, we are confident on the efficacity of similar association concerning other solutions than Dextran 70 (32%).

Animals↗
PubMed1992

In vitro endothelialization of carbon-coated Dacron vascular grafts.

Physical vapour deposition is used to coat vascular prostheses with pyrolytic carbon. This coating may facilitate the development of an endothelial monolayer in grafts implanted in laboratory animals. This in vitro study compared the adherence and growth of cultured porcine aortic endothelial cells (EC) seeded in vitro on carbon-coated Dacron, to uncoated prostheses. The cells were incubated at 5 x 10(4) cells/cm2. Progress was monitored at different times (TO + 2 hours, D 1, D 4, D 8) by microscopic observation, when cell counts were made; and by scanning electronic microscopy (SEM) to evaluate morphological EC-graft interactions. Cell adherence was independent of the carbon coating but cellular growth occurred only on carbon-coated Dacron. The SEM observations showed both the shape of the adherent cells, which were rounded on uncoated Dacron and extensively spread on carbon-coated prostheses, and the morphology of the carbon coating.

Blood Vessel Prosthesis↗
PubMed1992

[Can solid state Holter monitoring replace endomyocardial biopsy in patients with heart transplantation?].

Acute cardiac graft rejection after transplantation, the diagnosis of which is based on the findings of endomyocardial biopsy, is associated with a reduction in coronary reserve due to abnormalities of the microcirculation. But this reduction in coronary reserve cause silent myocardial ischaemia (SMI)? In order to assess the frequency of SMI and ventricular arrhythmias during rejection, 53 consecutive Holter recordings were performed in 32 patients (28 men, 4 women, average age 47 +/- 11 years) 11 months after transplantation and within 24 hours of endomyocardial biopsy. The recorder which was used (Monitor One TC) analysed the ST segment in 2 leads in real time: ST segment depression of more than 1 mm lasting over 40 ms, 0.08 s after the J point were considered to be diagnostic of myocardial ischaemia. Although the frequency of SMI is low and not specific for cardiac rejection, its duration was twice as long (80 mn vs 38 mn) in this condition. On the other hand, ventricular arrhythmias are common in cardiac rejection and correlated with its severity according to Billingham's classification (VES p = 0.045; doublets p = 0.035; non-sustained VT p = 0.006).

Adolescent↗