Search PubMed⌕ Search

Biomedical subjects

D Loisance

Publications and source records attributed to D Loisance.

At least 253 records · Page 14Linked to original sources
PubMedDate not supplied

Complement activation is involved in the structural deterioration of bovine pericardial bioprosthetic heart valves.

Disintegrated collagen fibers surrounded with protein deposits are a morphologic feature in torn, folded, and disrupted cusps of pericardial prostheses explanted for clinical dysfunction. New technologies for valve bioprostheses with improved durability require further investigation of molecular mechanisms initiating the deterioration of bioprosthetic valves. The authors' aim was to obtain experimental evidence of biologic factors contributing to the degradation of the bioprosthetic matrix. Clinically failed Mitroflow (22), Hancock (3), Ionescu-Shiley (2), and Sorin (1) valves were explanted after 69-170 months. Non calcific deterioration of the prosthetic matrix was studied with labeled antibodies to plasma proteins and cells. IgG, and complement proteins C1q, C3, and C4 were accumulated close to dissociated collagen bundles (26/28) throughout the prostheses. Fibrin was identified on the cuspal surface and in the deep disrupted areas. The fibrin peptides and proteolytic breakdown products of the complement components, the latter consistent with complement activation and chemotaxis for monocytes, were shown by immunoenzymic assay on Western blots from the valve extracts. The complement activation triggered by the IgG aggregates generates bioactive peptide signals that can activate macrophages (22/28) and neutrophil granulocyte elastase (22/24) able to cooperate with the mechanical stress in the breakdown of the chemically processed, non hemocompatible, and non-self macromolecular matrix.

Adult↗
PubMedDate not supplied

Survival outcomes of patients with giant cell myocarditis bridged by ventricular assist devices.

Giant cell myocarditis is a highly lethal disorder characterized by rapidly progressive congestive heart failure. The aim of this study was to describe the clinical course of patients with giant cell myocarditis who received a ventricular assist device. Patients with giant cell myocarditis were identified from the Multicenter Giant cell Myocarditis Registry. Bridging to cardiac transplantation in the giant cell myocarditis patients who received a ventricular assist device was compared with bridging in the general population of heart failure patients, as reported in the literature. Median posttransplantation survival for patients with giant cell myocarditis who received and did not receive ventricular assist devices was calculated by the Kaplan-Meier method and compared with use of the log-rank test. Nine patients with giant cell myocarditis who received ventricular assist devices were identified. Seven patients survived to transplantation, four were alive 30 days posttransplantation, and two survived to 1 year. The rate of successful bridging to transplantation in seven of nine patients (78%) is similar to that reported for other ventricular assist device recipients. Posttransplantation survival of 57% (4 of 7) at 30 days and 29% (2 of 7) at 1 year was significantly lower compared with 93% 1-year survival of the 30 patients with giant cell myocarditis who did not receive ventricular assist devices before transplantation (p<0.001). Ventricular assist devices can be an effective bridge to transplantation for patients with heart failure caused by giant cell myocarditis. Although their posttransplantation survival was poor in our series, a few patients had long-term survival.

Adolescent↗
PubMedDate not supplied

Pseudointima in inflow and outflow conduits of a left ventricular assist system: possible role in clinical outcome.

Activation of blood coagulation and thromboemboli have been shown to present significant clinical risks in patients supported with an left ventricular assist system (LVAS). The interaction of pseudointima (PI) with blood in the conduits of the device could be involved in these clinical complications. Our aim was to study the morphology of the PI versus duration of circulatory support. Novacor N 100 PC LVASs were explanted from 10 men and 2 women after a mean of 209 days (range 23-560 days) of circulatory assistance. PI in the inflow and outflow conduits were investigated with immunohistochemical assays. In the inflow conduits, a loosely adherent PI had built up from collagen type I and III fibers growing into and between fibrin deposits. Disorganized collagenous matrix and longitudinally oriented collagen fibers included alpha-smooth muscle actin positive cells with random orientation. Macrophages were concentrated in the fibrin and were dispersed throughout the extracellular matrix. In the outflow conduits, a thin, adherent PI was composed of regular collagen type I and III layers. Collagen type I fibers had grown into the woven Dacron and alpha-smooth muscle actin positive cells were oriented in the axis of the blood flow. Macrophages were concentrated in the Dacron and reached the inner collagen layers. Venous blood flow in the inflow conduits allows the development of a non endothelialized irregular collagenous matrix intermingled with fibrin and invaded by macrophages. These persistent structural features progress with duration of circulatory assistance and reflect matrix degradation and remodeling. The potential to release thromboembolic fragments from the non stable, thrombogenic PI may be involved in the thromboembolic or neurologic complications sustained by 5 of 12 patients who were on circulatory support for as long as 200 days.

Actins↗
PubMedDate not supplied

Postoperative CT follow-up of aortic dissection.

Computed tomography with contrast enhancement permits noninvasive follow-up of patients treated for aortic dissection. We used CT to examine 52 patients with aortic dissections for up to 14 years postoperatively. The mean interval between surgery and CT was 32 months. Computed tomography demonstrated the aortic graft in 45 patients. Persistent patency of a false lumen was observed in 40 cases. In one case, CT demonstrated extension of the dissection. No rupture or thoracic pseudoaneurysm was noted in our series.

Adult↗
PubMedDate not supplied

[Aortocoronary bypass].

Surgical revascularisation of the myocardium by aorto-coronary by-pass, has become in recent years, the operation of choice for the treatment of lesions of coronary arteriosclerosis. The quality of the results observed in our series, of 200 operated patients, and those reported by other authors, is emphasized. The problems raised by extension of this surgery, especially in the precise pre-operative assessment of ventricular function, the optimum material to use for realisatin of the graft and the course of coronary lesions after by-pass operations are then discussed.

Coronary Artery Bypass↗
PubMedDate not supplied

Cost and cost effectiveness of the mechanical and pharmacologic bridge to transplantation.

A prospective study has been carried out to evaluate the cost and cost effectiveness of the mechanical bridge (MB) or pharmacologic bridge (PB) to transplantation (HTx) in patients referred in cardiogenic shock (CS), who are candidates for Htx unresponsive to sympathomimetics. Selection between MB and PB was based on immediate efficacy of i.v. enoximone (2 mg/kg/BW) therapy. From 1986 to 1989, 37 patients who should have been immediately treated by MB entered the protocol. Six were unresponsive and rapidly received a Jarvik heart or left ventricular bypass (MB). Thirty-one improved (PB), with the need for HTx reconfirmed in 22 and performed in 14. Survival of the entire group was 70% and 51% at 1 and 3 months, respectively. Cost per patient was $45,843 ranging from 38,326 in PB patients to $84,683 in MB patients. Cost per patient transplanted after PB was $50,745. Cost per survivor at 1 year was $210,000 for all, ranging from $254,000 in MB to $192,455 in PB. Cost per added day of survival was higher in MB (+ 228%) at 1 month compared to PB. The difference was reduced at 1 year.

Adult↗
PubMedDate not supplied

The real impact of mechanical bridge strategy in patients with severe acute infarction.

Results obtained in the past 3 years in patients referred with acute myocardial infarction (AMI) and cardiogenic shock for a mechanical bridge to urgent transplantation permit one to assess the real impact of the present strategy in clinical practice. Ten patients (mean age = 49) were admitted in serious condition (CI = 1.8 +/- 0.2 L/min/m2, PCWP = 28 +/- 6 mmHg, systolic aortic pressure = 88 +/- 20 mmHg, urine output 11 +/- 20 ml/hr) and were treated by maximal sympathomimetic support and i.v. enoximone. Two had to be implanted with a total artificial heart (TAH) and one with a left ventricular assist device (LVAD) for recurrent fibrillation despite hemodynamic improvement, within 8 hr. Two have received transplants and are living well after 20 months. Seven who initially improved markedly have been listed as urgent transplant candidates: two of these have been successfully transplanted, and three died suddenly after 6, 25, and 45 days, respectively. One has undergone successful coronary surgery. One patient (age 62, diabetic) was secondarily rejected for a transplant and died. This experience clearly shows that despite initial spectacular hemodynamic improvement, which was due to optimized medical management, death rate before transplant because of sudden ventricular fibrillation remains unacceptably high. This should prompt early mechanical support, with less invasive systems, in patients with AMI.

Adult↗
PubMedDate not supplied

[Epithelial and stromal healing after radial keratotomy. Scanning electron microscopy analysis].

A study of corneal healing after radial keratotomy was conducted under scanning electron microscopy in 28 papio-papio baboons. The appearance of the incisions after follow-ups ranging from one hour to three and a half years postoperatively permits to emit some hypotheses regarding the precise mechanisms of action of radial keratotomy, as well as those governing any functional or anatomical complications susceptible to occur after the operation.

Animals↗
PubMedDate not supplied

Hemopump ventricular support for patients undergoing high risk coronary angioplasty.

Prophylactic implantation of a Hemopump (Johnson and Johnson, Skillman, NJ) has been evaluated in nine patients selected for high risk coronary angioplasty. They were unstable patients, refractory to maximal pharmacology, with indications for revascularization, but contraindications for surgery such as low ejection fraction and lack of material for bypass. In all, the target lesion was located on the last patent vessel. The pump was inserted under local anesthesia, without any graft. A specially designed occluder permitted avoidance of retrograde bleeding during implantation. The bypass flow ranged from 2.5 to 3.2 L/min, and permitted a rise in cardiac index from 2.05 to 2.55 L/min/m2, with a drop in capillary wedge pressure from 13 (7-18) to 10 (7-13) mmHg. During balloon inflation, no electrocardiographic changes were observed, because only minor ventricular arrhythmias occurred. No significant hemolysis was seen (plasma free hemoglobin less than 10 mg/dl in all) after 2 hr of pumping. The only limitation of the technique appears to be difficulty at the time of implantation from narrow, stenosed, or tortuous iliofemoral arteries (3 patients). This experience strongly supports the benefit of temporary left ventricular Hemopump support in high-risk situations and clearly shows the need for a smaller pump.

Aged↗
PubMedDate not supplied

[Cardiac transplantation in an extreme emergency].

Urgent cardiac transplantation in very unstable patients, kept alive in intensive care unit, is a significant (34 percent) part of the Henri-Mondor's transplantation program. Nineteen patients received a donor graft from january 1986 to october 1988. Sixteen were bridged pharmacologically as 5 received a mechanical bridge. Time on waiting list ranged from 12 to 21 days. Six patients died in the first post-operative month. Death was due to uncontrolled preoperative problems in 5, donor graft failure in one. The survival rate at one year was 52 percent, to be opposed to 76 percent in stable patients. These figures must be considered when selecting the priority of the transplantation candidates.

Adult↗
PubMedDate not supplied

[Enoximone and the therapeutic strategy in patients awaiting emergency cardiac graft].

Enoximone is a positive inotropic agent belonging to the group of phosphodiesterase F-III inhibitors. The drug was tested in 34 patients uncontrolled by sympathomimetic drugs and referred to our department for urgent heart transplantation or circulatory assistance. After insertion of a Swan-Ganzgatheter and a radial artery catheter for haemodynamic monitoring, enoximone was administered as a 15-minute intravenous bolus injection of 1 to 2.5 mg/kf every 8 hours, in addition to sympathomimetic agents. Clinical and haemodynamic improvement was observed after thirty minutes in 30 patients. The cardiac index rose from 1.82 to 2.67 l/min/m2 and the pulmonary wedge pressure fell from 30.8 to 18.9 mmHg. Systemic arterial resistance decreased from 2170 to 1520 dyn. s. cm-5, and pulmonary resistance from 5.5 to 4.6 Wood units (p less than 0.01 for all values). Four patients had no haemodynamic improvement and were put on circulatory assistance, using a Jarvik 7 total artificial heart in 3 of them and heterotopic circulatory assistance in one. After clinical investigation for contra-indication to heart transplantation, and as their improved haemodynamic status permitted, 12 of the 30 patients were considered suitable (group B) for heart transplantation. Transplantation was performed within a week of admission in 11 patients without any need for mechanical assistance. One of the group B patients who required implantation of a Jarvik 7 artificial heart died after 12 hours of assistance. Eighteen patients were considered unsuitable for transplantation (group A) and treated medically.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

[Endothelial effects of radial keratotomy in a non-human primate].

The study of the endothelial repercussion of radial keratotomy has been done on 33 corneas of 21 non human primates, using Scanning Electronic Microscope. Various lesions has been observed; the relationship between these lesions and the surgery parameters have been studied. One can conclude that the lesions are constant; their severity is related to the number and the depth of the incisions; as for their evolution, they do not seem to worsen with time during the experimental study (1 hour to 18 months).

Animals↗