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Biomedical subjects

D Loisance

Publications and source records attributed to D Loisance.

At least 19 recordsLinked to original sources
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↗
PubMed1992

Extracellular matrix covered biomaterials for human endothelial cell growth.

The aim of this study is to optimize conditions for growing endothelial cells on vascular biomaterials. Bovine cornea endothelial cells (BCEC), stimulated by basic Fibroblast Growth Factor (bFGF) secrete an extracellular matrix (ECM) similar to the Descemet membrane produced in vivo by these cells. This ECM, obtained by removing BCEC with an hypotonic shock can be used as a substratum for other endothelial cell growth. Human endothelial cells (HEC) were purified from omentum that was digested with a solution of collagenase-dispase, then filtered through nylon meshes. The cells were further purified by centrifugation onto a Percoll gradient. A comparative study on the attachment and growth of HEC on various coatings (laminin, poly-L-lysine, fibronectin or ECM) indicates that ECM is the most performing substratum. The quality of this endothelium was confirmed by the presence of factor VIII, and MHC class I and the absence of class II antigens.

Animals↗
PubMed1992

[Cost and efficacy of therapeutic strategies in candidates for heart transplantation as salvage therapy].

A study of the real cost, the cost-effectiveness of treatment was performed in 31 cases of cardiogenic shock referred for cardiac transplantation, treated in a flexible therapeutic protocol associating implantation of an expensive mechanical circulatory support system (mechanical bridge) or treatment by drugs alone (pharmacological bridge) depending on the efficacy of IV enoximone. The average patient cost was 238,386 French Francs, ranging from 440,353 FF in patients receiving the mechanical bridge to 199,296 FF in those receiving the pharmacological bridge. The cost-effectiveness ratio expressed either as cost per patient surviving the different stages of the disease or as cost of obtaining an additional day of survival at the same intervals was twice as favourable in the group receiving the pharmacological treatment. This study suggests that IV enoximone and strict selection procedures for candidates for the more expensive option should help bring together the interest of the individual patient and of society as a whole.

Adult↗
PubMed1992

Coronary hemodynamics during hemopump left-intraventricular assistance.

Hemopump left intraventricular pumping (HP) can permit percutaneous transluminal angioplasty (PTCA) in high-risk patients. Benefits may be related to left ventricular unloading or myocardial perfusion improvement, or both. Direct ultrasonic measurements of coronary blood flow were made in the dilated vessel after a successful PTCA in five patients. A 3 Fr intracoronary Doppler catheter was placed in the coronary artery to measure flow velocities (maximal or diastolic velocity; minimum or systolic velocity and mean velocity). A SwanGanz catheter was used to measure the cardiac index and pulmonary capillary wedge pressure. Mean aortic pressures were monitored through an 8 Fr guiding catheter. Measurements were made after a 5-min period of minimal speed (T0) of the HP to avoid retrograde regurgitation through the turbine; during the increase from minimum to maximal speed (T1); after a 5-min period of maximal HP flow (3l/min) (T2) and after HP was pulled back (T3). From T0 to T2, cardiac index rose from 1.93 +/- 0.38 to 3.26 +/- 0.35 l/min/m2 and capillary wedge pressure decreased from 18 +/- 6 to 13 +/- 5 mmHg (p less than 0.05); from T2 to T3, cardiac index decreased to 2.4 +/- 0.4 while capillary wedge pressure increased to 17 +/- 5 (p less than 0.05). Mean arterial pressure and heart rate did not change significantly throughout the study. When the hemopump flow was raised to high speed, coronary blood flow increased immediately but returned shortly to baseline values.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1991

[Coronary vascular reserve in heart transplantation. Normalization after therapy for rejection].

Acute rejection is associated with severe impairment of coronary reserve in heart transplants. To evaluate the effects of rejection therapy, coronary reserve was assessed in 6 patients before and after treatment of an acute episode of rejection. Coronary reserve was significantly enhanced after rejection therapy (4.7 +/- 0.8, vs 2.3 +/- 0.5, P less than 0.001) and was not significantly different from that of transplanted patients without rejection (5.4 +/- 0.8). This study provides evidence that alterations of coronary reserve due to acute rejection are reversible after treatment of the rejection episode.

Acute Disease↗
PubMed1991

Physiologic assessment of milrinone therapy in severe heart failure patients.

To assess the inotropic, vasodilator, and after-load-reducing effects of intravenous milrinone in patients with severe congestive heart failure, a simple noninvasive echocardiographic study coupled with a right catheterization was performed in 12 patients. Milrinone was administered intravenously as a 50 micrograms.kg-1 bolus followed by a 24-h milrinone infusion at a rate of 0.5 mg.kg-1.min-1 [corrected]. Echocardiographic left ventricular end-diastolic diameter (Ded), end-systolic diameter (Des), and wall thickness were measured at baseline and at 24 h of milrinone infusion, before and after a sublingual nitrate administration (0.8 mg of nitroglycerin) that induced load variations. Hemodynamic measurements were performed simultaneously. Left ventricular end-systolic meridional wall stress (Ses) was then calculated. The slopes of percent fractional shortening (percent FS)/Ses and Ses/Des, obtained during sublingual nitrate administration, were traced. Both end-systolic relations are an index of the contractile state. Milrinone therapy improved hemodynamics in all patients, resulting in stabilized hemodynamic conditions between 12 and 24 h of continuous milrinone infusion. At these times, the cardiac index increased to 30% while the capillary pulmonary wedge pressure and systemic vascular resistance decreased to 26 and 24%, respectively (all p less than 0.01). The average slope of Ses/Des shifted upward from 47.5 +/- 30 to 69.25 +/- 34 (p less than 0.05) and the average slope of (percent FS)/Ses shifted from -0.032 +/- 0.025 to -0.082 +/- 0.061 (p less than 0.01), both variations attesting the inotropic effect of milrinone.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Percutaneous transluminal angioplasty of the common trunk during the acute phase of myocardial infarction].

The prognosis of cardiogenic shock in the acute phase of myocardial infarction has been transformed since the introduction of techniques of myocardial revascularisation. We report the case of a patient in cardiogenic shock after a large anterior myocardial infarct in whom failure of early thrombolytic therapy led to referral for emergency percutaneous transluminal coronary angioplasty. The success of the procedure on the patient's haemodynamic condition was life-saving. The originality of this case resides in the fact that revascularisation concerned the left main coronary stem.

Angioplasty, Balloon, Coronary↗
PubMed1991

[Modern techniques of assistance and mechanical replacement of cardiac function].

There has been intensive technological and clinical research for many years into the assistance and mechanical replacement of cardiac function. The simplest systems (extracorporeal circulation using centrifuge pumps, hemopump) and more complex systems (orthotopic or heterotopic pneumatic ventricles, electric ventricles) have been shown to be effective in a variety of situations which up to now could not be controlled by pharmacological methods. These situations are made amenable to improvement by the application of these techniques. They make it possible to await the recovery of autonomous function or, in its absence, transplantation. Experience over the past 30 years provides guidance for current research into the artificial heart.

Heart Diseases↗