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Biomedical subjects

F Laborde

Publications and source records attributed to F Laborde.

At least 73 records · Page 4Linked to original sources
PubMed1989

Morphological survey of a new pericardial valve prosthesis (Pericarbon): long-term animal experimental model.

A long-term experimental morphological study was carried out in 22 adult sheep to evaluate a new pericardial valve prosthesis (Pericarbon), which had been implanted in the tricuspid or mitral position. This prosthetic device differs substantially from others in that its construction design consists of two sheets of glutaraldehyde-fixed bovine pericardium and a low-profile flexible plastic stent (Delrin) covered by a pyrolytic carbon coated dacron fabric; one pericardium sheet forms the three cusp valve and is sutured to the second, which lines the inner surface of the plastic stent. Twenty animals were sacrificed at fixed intervals, while 2 are still living at about 3 years post-surgery. Tricuspid explants (mean duration, 295 days) showed significant fibrous sheathing and a mean calcium X-ray score of 1.75. Mitral medium-term explants (mean duration, 325 days) had fairly well preserved pliability and a mean calcium X-ray score of 2.5. Long-term explants (mean duration, 467 days) were all stiffened by calcification (mean score, 3.75). None of the explants had tears or perforations. Medium or long-term mechanical failure was not observed. A significant host tissue reaction took place in the tricuspid but not in the mitral position. Calcification mainly involved the collagen fibres and increased progressively with time. Ultrastructural studies invariably disclosed fair preservation of graft tissue structures, surface reendothelization and initial nuclei of calcification within the collagen fibres. These morphological findings confirm the potential advantages of this new prosthetic device and warrant long-term clinical trials to test its actual durability.

Animals↗
PubMed1989

Aortocoronary bypass without extracorporeal circulation: why and when?

Thirty patients have been operated on since July 1986. The mean age was 55 years (range 32-68). Twenty-three simple and 7 double bypasses were performed. The internal mammary artery and 1 prosthetic conduit were used for the 29 left anterior descending (LAD) anastomoses and saphenous vein for the others [5 right coronary artery (RCA), 3 diagonal]. The use of an implantable Doppler probe for continuous monitoring during the 1st postoperative week confirmed patency and gave an estimated flow (mean: 79.23 ml/min, range 43.4). There were no deaths and no cases of infarction or ischaemia, but stress test performance improved. The main advantage of this rapid and safe technique was avoidance of morbidity of extracorporeal circulation (ECC) and limited operative myocardial ischaemia. Criteria of selection were unstable, permanent angina (14); unsuccessful PTCA (8) PTCA and failure (5 emergency cases), redo surgery (4); poor LV function (EF less than 20%) (3); fibrinolytic treatment or severe coagulopathy (2). The ideal patient has severe stenosis with or without retrograde filling of LAD with either RCA or circumflex (which require a lateral thoracotomy).

Blood Vessel Prosthesis↗
PubMed1989

Evaluation of Pericarbon valve prosthesis: in vitro, ultrastructural, and animal studies.

Pericarbon, a new generation pericardial valve, is characterized by a single, three cuspal shaped pericardium sheet, which is sutured to a second sheet lining the inner surface of the plastic, low profile stent. A coating of hemocompatible carbon film covers all the exposed, nonbiological surfaces. Optimal preservation of collagen and graft cells is achieved by fresh tissue glutaraldehyde fixation and cusp shaping without mold. Accelerated fatigue testing showed a duration of over 150 million cycles, a figure much higher than that observed when current pericardial and porcine valves were tested with the same apparatus. Results of long-term (greater than 7 months, average 10.5) implantation in 20 sheep (13 mitral, 7 tricuspid) disclosed no case of mechanical failure, mild to moderate primary calcification in older explants, and significant fibrous tissue overgrowth only in the tricuspid position. Transmission electron microscopy studies revealed collagen and elastic fiber integrity, no significant plasma protein insudation, and well-preserved graft cells. Re-endothelialization by host cells was a regular finding on scanning electronic microscopy. Early ultrastructural nuclei of calcification were seen mostly on collagen fibers. Pericarbon presents basic changes in pericardial valve design, and optimal morphological preservation is obtained after industrial processing. Accelerated fatigue tests in vitro show long duration. At medium long-term animal experimental follow-up, mechanical failure was not observed; significant host tissue reaction occurred in the tricuspid but not in the mitral position; primary calcification increased progressively with time and involved mainly collagen fibers.

Animals↗
PubMed1988

Aortic 125I-albumin transport in patients with Marfan's syndrome and annuloaortic ectasia.

The morphologic, biochemical, and mechanical abnormalities of connective tissue fibrous proteins in Marfan's syndrome have been well studied, and their role in cardiovascular complications is well accepted. Less is known, however, about the state of the amorphous components of the aortic connective tissue. In the course of a study of transmural transport in blood vessels, we have had the opportunity to study dystrophic aorta from two young men who survived elective surgery; both with aortic insufficiency (AI) histologically compatible with Marfan's syndrome. One had recurrent chronic dissecting aneurysm (RCDA) as well. The aorta of the first (but not the second) was histologically compatible with Marfan's syndrome. Fresh specimens of intact ascending aorta were incubated in Krebs solution, pH 7.4, containing 125I-labelled bovine serum albumin for 2 h at 37 degrees C. The samples were then frozen, and serially sectioned in the plane of the lumenal surface. The radioactivity of the 20-micron thick sections was then determined, and expressed as a tissue/labelled solution concentration ratio. Transmural profiles of these ratios revealed no difference between the aorta of the RCDA patient with non-specific aortic dystrophy, and that of a 70-year-old man undergoing aortocoronary bypass. However, in the patient with aortic histology compatible with Marfan's syndrome, the average media concentration ratio was 5-fold less (4% vs. 20%).

Adult↗
PubMed1988

Rupture of the right ventricular free wall. An unusual complication of mediastinitis after cardiac surgery.

Of 2171 patients who underwent open heart surgery between 1981 and 1986, 41 (1.8%) developed postoperative mediastinitis and were treated by closed irrigation drainage or open chest therapy. Six patients, (mean age 59 years) developed rupture of the right ventricular free wall. The primary procedures were: resection of akinetic fibrous plaque (2), mitral valve replacement (1), coronary bypass grafting (1), removal of a left atrial myxoma (1) and repair of post-infarction rupture of the left ventricle (1). In 2 patients, rupture occurred in the operating theatre during revision of the irrigation drainage. Both patients died after repair. In 4 patients, rupture occurred during coughing. One died before surgery. In the 3 other cases, the defects were repaired either by direct suture (2 patients) or with a pericardial patch (1 patient) with the aid of normothermic extracorporeal circulation. Three days later, a muscular flap (pectoral or dorso-lumbar) was mobilized to protect the mediastinal viscera. All 3 patients are alive and well. When bleeding occurs during treatment of mediastinitis, an immediate exploration with extracorporeal circulation to close the defect should be considered.

Aged↗
PubMed1987

Clinical use of automatic implantable defibrillators.

We implanted the automatic implantable defibrillator model B (AID-B) in 11 patients (pts). Seven pts had coronary disease with sustained VT, and/or VF. Two had syncopal VT due to primary cardiomyopathy, and two pts had syncopal torsades de pointes (Tdp) without cardiac disease (1 long QT syndrome). These arrhythmias occurred despite antiarrhythmic drugs or beta blockers. Four pts had implanted: an epicardial patch by thoracotomy, an intra-atrial string electrode by the jugular vein, then AID-B by abdominal route. In 7 pts, subcostal approach was used, for implanting simultaneously 2 epicardial patches and the AID-B itself. During the operation, VT, Tdp and/or VF were induced in all pts by 50 Hz alternating current. The defibrillation threshold (DT) between atrial catheter and epicardial patch was less than 15 J in 4 pts, and greater than 25 J in two, requiring a larger patch in 1, and replacement of atrial electrode by another patch in the 2nd pt to obtain a DT less than 20 J. In the 6 pts implanted with 2 patches, DT was always less than 25 J. In 3 pts, DT was markedly higher for VF (25 J) than for VT (less than 15 J). One pt died from pulmonary embolism, another died after 3 years, before replacement of a failing battery, and a third died from progressive congestive heart failure, 6 months later. Eight pts are alive with a follow-up greater than 6 months. Local aseptic reactions obliged a removal of the implant in 2 pts operated by bifocal approach, and none when the subcostal route was used.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

[Long-term clinical results of the implantable automatic defibrillator].

Between October 1982 and May 1986, 12 patients were implanted with an automatic defibrillator AID-B; 7 had coronary artery disease, 2 had dilated cardiomyopathies and 3 had torsades de pointe with or without long QT intervals. Five patients had a thoracic approach with a left ventricular patch and implantation of a right atrial endocavitary electrode. Thereafter a subcostal approach was used with 2 patch electrodes. Two of the first 5 patients rejected the device, but this complication was not observed in the remaining 7 cases. The threshold of defibrillation was greater than 25 joules in 1 case out of 5 with a patch and endocavitary electrode. This threshold was less than 25 joules in all patients with 2 patch electrodes. The AID-B was triggered in less than 20 seconds. One patient died of pulmonary embolism 8 days after implantation; 2 others had a temporary aggravation of their arrhythmias. There were no cases of inappropriate activation of the AID-B device during follow up: 5 patients had no arrhythmia or defibrillation. The 6 others had 2 to 35 defibrillations with documented arrhythmias before or after defibrillation. One patient suffered a sudden death after exhaustion of the device which had functioned on two occasions but had not been replaced for economic reasons. The technique of implantation has been simplified, so limiting local complications. This device is reliable and represents an effective palliative treatment of sudden death due to ventricular arrhythmias.

Adult↗
PubMed1986

[Ventricular tachycardia of ischemic origin. Surgical treatment by encircling thermo-exclusion using the Nd-Yag laser].

Refractory and recurrent ventricular tachycardias are a common cause of death after myocardial infarction. The occurrence of intraventricular re-entries can be prevented by a new surgical treatment based on encircling thermic exclusion. The Nd-YAG laser beam offers 2 major advantages over previous techniques: it acts rapidly with minimal myocardial damage and can even be used in patients with left ventricular dysfunction.

Coronary Disease↗
PubMed1986

Comparison of perioperative and postoperative phasic blood flow in aortocoronary venous bypass grafts by means of pulsed Doppler echocardiography with implantable microprobes.

Although graft dimension and hemodynamic variables have been suggested as important determinants of the functional results of aortocoronary bypass grafting, there is no easy-to-use bedside method of monitoring phasic blood flow in coronary bypass grafts. We developed a miniaturized implantable silicone pulsed Doppler flow probe linked to a classic 8 MHz pulsed Doppler system. This apparatus has an adjustable range-gated time system that permits accurate measurement of diameter (D, in mm), cross-sectional blood flow velocity (Vm, in cm/sec), and coronary bypass graft flow (CBGF, in ml/min) as pi D2/4 X Vm X 60. Ten patients (55 +/- 7.2 years SD) with preoperative left ventricular ejection fractions over 45% received the implantable flow probes during the aortocoronary venous bypass procedure. Closure of the chest altered systolic and diastolic components of flow velocity and CBGF decreased from 131 +/- 65.8 to 94 +/- 55 ml/min (-28%; p less than .01). Comparison between early postoperative values (intensive care unit) and values 6 days later showed significant increases in diameter from 4.2 +/- 0.9 to 5.3 +/- 0.9 mm (p less than .01) and in CBGF from 130 +/- 112 to 204 +/- 86 ml/min (p less than .01). We conclude that the implantable pulsed Doppler microprobe is a sensitive bedside method for monitoring aortocoronary bypass graft diameter and blood flow in the postoperative period.

Blood Flow Velocity↗
PubMed1986

Experimental evaluation of porcine-valved conduits processed with a calcium-retarding agent (T6).

The effectiveness of a water-soluble C-12 alkyl sulfate (T6) (U.S. Patent No. 4,323,358) in retarding bioprosthetic calcification was evaluated in 23 porcine-valved conduits (13 T6-treated conduits and 10 controls) implanted in young sheep between the right ventricle and the pulmonary trunk. The grafts were divided into three groups according to the period of function: Group I, less than 2 months; Group II, 2 to 4 months; and Group III, 5 to 7 months. In Group I (four T6 and four controls), endocarditis occurred in five cases. In Group II (three T6 and three controls), four conduits showed severe fibrous peel ingrowth. In Group III (six T6 and three controls), fibrous peel was the main feature in four conduits and calcium deposits occurred in the porcine aortic wall in all cases, with cusp involvement in two; in both T6-treated and control conduits, chemical analysis showed a much lower calcium content of the cusps (8.45 +/- 80 versus 2.95 +/- 1.52 mg/gm dry weight, respectively) than that reported in other animal or human explants. The grade of calcification in control and T6-treated conduits was equal on x-ray analysis, and no differences in calcification patterns were noted on electron microscopy. This experimental model shows a low degree of cusp calcification and no significant differences between T6-treated and control conduits. Peel formation markedly interferes with performance of the porcine-valved conduit. The results of this analysis indicate that valved conduits are not the optimum model for evaluating calcium-retardant agents in biological valves.

Animals↗
PubMed1985

Surgery for prosthetic valve endocarditis.

Infectious endocarditis is the main complication after prosthetic valvular replacement. 2 problems remain unsolved: 1. Diagnostic: Fever, heart failure and paravalvular leaks should be indications for re-operations. 2. Technical: perfect fixation of the prosthetic valve is a surgical challenge. The difficulties as shown here are the cause for so many operative techniques. Early surgical intervention is the best method to prevent myocardial failure.

Abscess↗