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Biomedical subjects

D Loisance

Publications and source records attributed to D Loisance.

At least 109 records · Page 6Linked to original sources
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↗
PubMed1991

[Heart transplantation in acute myocardial infarction].

Ten patients with cardiogenic shock after acute myocardial infarction were referred to the University Hospital Henri Mondor as candidates for cardiac transplantation. The period before transplantation was bridged by maximal pharmacological support including sympathomimetic and phosphodiesterase inhibitor inotropic agents and, in non-responders, by mechanical ventricular assist devices (1 case) or artificial hearts (2 cases). The 7 patients who improved with optimal pharmacological support alone had a good initial course. However, only two of these patients were finally transplanted, three died suddenly either in the intensive care unit or after withdrawal of intravenous drugs and hospital discharge. One patient remained well and after coronary bypass surgery, enjoys good quality life. One patient was found secondarily to be a poor candidate for transplantation and died shortly after. The outcome of 2 of the 3 patients who did not respond to pharmacological treatment and who required mechanical support was spectacularly good and enabled successful cardiac transplantation. Our experience underlines the numerous difficulties of different natures of cardiac transplantation in this indication, the value and risks of the new inotropic agents, and the real but limited role of heroic procedures such as the artificial heart.

Adult↗
PubMed1991

[Conflicting xenograft. Role of preoperative total lymphoid irradiation].

This study deals with an experimental model of discordant cardiac xenograft between 24 donor lambs of the Préalpes race and 24 recipient Camborough pigs divided up into 4 groups: I control (6) without immunosuppressive treatment; II (5) with pharmacological immunosuppression (IP); III (13) with PI and total lymphoid irradiation (TLI) and immediate graft, divided up into IIIa (5) with high-rate (HR) TLI and IIIb with low-rate (LR) TLI; IV (4) with a two-week lapse between TLI and grafting. The best graft survival rate (GSR) is obtained either after delayed LR-TLI or after LR-TLI without delay. This study seems to be the first one demonstrating that for discordant xenogenic grafts, TLI associated to PI with cyclosporin A (Cy A) significantly prolongs the survival of the graft (30 times).

Animals↗
PubMed1991

[Coronary disease in patient following heart transplantation].

Coronary artery disease is a common and particularly severe complication of cardiac transplantation because it may cause progressive destruction of the graft by acute or chronic ischemia. The ischemia is usually silent because of cardiac denervation. Cardiac failure related to graft dysfunction, asymptomatic infarction on the ECG, or sudden death, are sometimes the only signs of severe coronary disease. The prevalence of coronary lesions has been evaluated by coronary angiography at nearly 25% at 2 years and 50% at 5 years. The distribution and morphology of the lesions are characteristic: diffuse concentric, irregular and occlusive, predominantly distal stenoses, without a distal and usually without a collateral circulation. The histological features are variable: the association of medial necrosis, severe endothelial lesions and intense parietal inflammation are suggestive of acute arteriolitis, often present during acute rejection, may be related to a common pathological process. Diffuse obliterative arteriolar lesions with concentric proliferation of medial smooth muscle are the usual appearances in transplant patients who have died or been retransplanted. There is no non-invasive diagnostic method sufficiently sensitive of specific which justifies the practice of many groups of systematic annual coronary angiography in transplanted patients. The pathogenesis is poorly understood and probably multifactorial: disorders of lipid metabolism, immunological factors, the atherogenic role of Cytomegalovirus infection. The absence of an identifiable risk factor makes preventive measures difficult. The evolutive risk justifies retransplantation in selected patients, the results of which are less satisfactory but which reduces the risk of acute coronary events and sudden death.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Angiography↗
PubMed1991

[Severe calcified aortic stenosis in patients aged 80 or older. Apropos of 65 cases surgically treated].

From 1981 to 1989, 65 patients over 80 years were submitted to surgery for severe calcific aortic stenosis. Thirteen patients were in NYHA II, 31 in NYHA III, 21 in NYHA IV. Mean valve area was 0.52 +/- 0.14 cm2 and mean aortic valve gradient was 62 +/- 18 mmHg. Left ventricular function was altered (ejection fraction less than 40%) in 33 patients. Six patients had a previous balloon aortic valvuloplasty. Bioprosthesis were used in all 65 patients associated to CABG (in 5) and mitral valve replacement (in 1). One month mortality was 19 cases (29%) due to cardiac failure (in 10) pulmonary (in 7) and neurological (in only 2) complications. Early mortality was nearly significantly correlated to NYHA stage (p = 0.08) and preop renal insufficiency (p = 0.07). It was significantly correlated to function (40% mortality when ejection fraction less than 40%, 16% in others) and to operations on emergency basis (5 deaths over 6). Hospital morbidity was 68%. There were 5 late deaths. Among the 41 long-term survivors (3 mths-7yrs) 29 are in NYHA I, 10 in NYHA II and 2 in NYHA III due to valve failure. The actuarial survival probability is 65% at one year, 50% at 5 years. In summary good long-term results justify to take a high post operative risk in octogenarians. Early surgery before left ventricular impairment improves the survival.

Actuarial Analysis↗
PubMed1990

[Cardiac transplantation: indications and results].

Although many problems remain, cardiac transplantation is now associated with a 5 year survival rate of about 70 per cent which is a very acceptable therapeutic result in patients with cardiac failure and no other medical or surgical alternative. Parallel improvement in the medical management of chronic cardiac failure has prolonged survival of many patients. Transplantation should only be considered if the benefits not only in terms of survival but also in terms of quality of life, are greater than of survival but also in terms of quality of life, are greater than those of medical treatment of the cardiac disease. The indications and timing of cardiac transplantation are therefore based on a complex prognostic evaluation adapted to each individual case which may eventually need reconsideration. Satisfactory results depend on strict patient selection with respect for the surgical indications and contra-indications.

Adult↗
PubMed1990

Effect of plasma volume expansion on hemodynamics and atrial natriuretic factor release in heart-transplant recipients.

Plasma atrial natriuretic factor (ANF), plasma cyclic guanosine monophosphate (cGMP), plasma aldosterone, plasma-renin activity (PRA) and hemodynamic parameters were measured in heart-transplant recipients and control patients (chest pain syndrome) during right-sided heart catheterization under basal conditions and in response to an intravenous saline load. Basal plasma ANF and cGMP were higher in heart-transplant recipients than in control patients, whereas PRA and plasma aldosterone did not differ. The high plasma ANF levels in heart-transplant recipients did not result from high atrial pressures but appeared to be related with elevated atrial dimensions and cyclosporine-induced renal failure. During volume expansion, plasma ANF increased in control patients and remained elevated during the postinfusion period. In heart-transplant recipients, the changes in plasma ANF were less marked despite identical increases of atrial pressures. The sluggish response of plasma ANF in this group was associated in the postinfusion period with a nonreturn of the hemodynamic parameters to their basal values in contrast with what was observed in control patients.

Adult↗
PubMed1990

Prophylactic intraventricular pumping in high-risk coronary angioplasty.

The 'Hemopump', an axial flow pump, when inserted in the left ventricle brings about mechanical unloading of the ventricle, thus reducing the risk of cardiac arrest during coronary angioplasty. In this study eight very ill patients with unstable myocardial ischaemia and various contraindications for coronary artery surgery were selected for coronary angioplasty with insertion of the hemopump. Anatomical difficulties prevented insertion in three patients, but coronary angioplasty was carried out successfully with the pump in place in the other five. When the pump was working the cardiac index rose by an average of 23% (8-50%) and the pulmonary capillary wedge pressure fell by 17% (0-22%). Though electrocardiographic monitoring showed temporary rhythm instability during angioplasty in four of the five patients, there was no clinical deterioration. Four of the five patients are symptom-free on medical treatment and the other is well after surgical revascularisation.

Aged↗
PubMed1990

Polyurethane arterial prosthesis: experimental evaluation.

Two types of microporous polyurethanes have been evaluated both in vitro and in vivo. In vitro polyurethane disks have been seeded by endothelial cells from bovine aortic origin and from fresh human greater omentum. Various pretreatments permit comparison of six different experimental groups. The benefit of poly L lysine, laminin, fibronectin and previous astrocyte cell seeding is shown. The cell proliferation was assessed daily, using trypan blue in Malassez cells. Cell identification was performed by class I MHC antigen characterization and factor VIII staining. In vivo, 4 mm polyurethane arterial prostheses were implanted as carotid interpositions. Evaluation of polyurethane, both in vitro and in vivo, failed to demonstrate a satisfactory hemocompatibility of the material. However, previous treatment of polyurethane with laminin, fibronectin, and astrocyte cell seeding improves the biologic characteristics of the raw material.

Animals↗
PubMed1990

Enoximone improves selection of candidates for urgent cardiac transplantation.

Immediate cardiac transplantation, or urgent implantation of devices for mechanical support of the failing heart, has been shown to be effective as life-saving procedures in patients with cardiogenic shock unresponsive to maximal sympathomimetic treatment. The intravenous administration of enoximone in these patients, in addition to previous inotropic support, should permit a 'buying of time' strategy, leading to a reduction in the need for complex, invasive and costly techniques, such as artificial hearts. In addition, it should permit improved selection of candidates for cardiac transplantation. A prospective study was started in 1985 to obtain data on the haemodynamic and clinical efficacy of intravenous enoximone in these critically ill patients, and to determine the time gained for evaluation of the need for urgent transplantation. Cardiac index rose from 1.82 +/- 0.26 litres/minute/m2 to 2.67 +/- 0.56 litres/minute/m2 after 30 minutes, while pulmonary capillary wedge pressure decreased from 29.9 +/- 7 mm Hg to 18.0 +/- 7 mm Hg (n = 30). This early beneficial effect waned progressively after 6 hours. Prior to the next intravenous infusion at 8 hours, cardiac index was 2.07 +/- 0.53 litres/minute/m2 and pulmonary capillary wedge pressure was 25 +/- 8.5 mm Hg. Only four patients could not wait for a biological graft and had to be implanted with a complete artificial heart (3 patients), or a ventricular assist device (1 patient). In all, 30 patients improved and their increased survival allowed a re-evaluation for cardiac transplantation itself; 13 were rapidly (1.7 days; range 0.5-5) confirmed as good candidates. As a whole, this strategy compares favourably with the results of a strategy based on mechanical bridging alone.

Adult↗