Search PubMed⌕ Search

Biomedical subjects

P Nataf

Publications and source records attributed to P Nataf.

At least 73 records · Page 4Linked to original sources
PubMed1995

Evaluation of cryopreserved arteries as alternative small vessel prostheses.

Biologic or synthetic grafts have had limited success in small vessel applications. Studies were initiated to assess the potential use of cryopreserved (CP) arteries as coronary artery bypass conduits. Sheep carotid arteries (internal diameter: 4 mm; length: 10 cm) were cryopreserved in a nutrient media containing 10% DMSO and were stored in a nitrogen vapor at -150 degrees C. After thawing, histological, enzyme-histochemical and functional studies showed slight histological alterations, preservation of enzymal activities and an abolition of the contractile response. In a sheep model, arterial substitution of a 10 cm segment of carotid artery was realised by implantation of fresh autografts ( n = 4); fresh allografts (n = 9) and CP allografts (n = 9). After 3 months, all autografts were patent with slight histological alterations. Fresh and CP allografts showed similar modifications: patency rate was 7/9 in both groups. Intimal thickening with cell proliferation was seen in fresh (3/7) and CP (4/8) arteries; loss of smooth muscle medial cells was constant. Adventitia was always involved by a marked inflammatory reaction. One characteristic of CP allografts was the frequent presence of large dystrophic calcifications. In conclusion, morphologic and functional arterial changes occurred after freezing and thawing. In spite of vascular rejection, the patency rate of allografts after 3 months of implantation in arterial circulation remained high and does not seem influenced by cryopreservation.

Animals↗
PubMed1995

[Iatrogenic left coronaro-atrial fistula after mitral valve replacement: apropos of a case].

The authors report a case of an iatrogenic fistula between the left circumflex coronary artery and left atrium. The fistula was a complication of reoperation to replace a mitral valvuloplasty annulus by a mechanical hemi-disc prosthesis (Saint Jude Medical). Diagnosis was made by transoesophageal echocardiography and confirmed by coronary angiography. The patient underwent external ligature under cardio-pulmonary bypass.

Coronary Angiography↗
PubMed1994

Intraatrial insertion of a mitral prosthesis in a destroyed or calcified mitral annulus.

Infectious lesions and extreme calcification of the mitral valve annulus can make classic anatomic implantation of a prosthesis impossible. Confronted with these circumstances, we have developed a technique of intraatrial insertion of a mitral prosthesis. The prosthesis has been modified by enlarging the circumference of the sewing ring with a Dacron collar. The collar can be sutured to the left atrial wall above the mitral annulus. From 1981 to 1989, this technique has been employed in 36 patients: 15 had acute valve endocarditis with destruction of the mitral annulus and 21 had extensive annular calcification. In all cases, circumferential or partial intraatrial insertion permitted a secure implantation of the prosthesis. One operative death was related to the technique. It was an intractable bleeding caused by tearing of the very thin and fragile wall of the left atrium in a kidney transplant patient. Four patients were reoperated on for periprosthetic leak, in 3 of whom healing and cleaning of the mitral annulus permitted annular implantation of a prosthetic valve. There was no ventricular wall rupture. Our results suggest that the technique can be performed in high operative risk patients when mitral valve replacement is impossible by conventional techniques.

Calcinosis↗
PubMed1994

[Chronic constrictive pericarditis. A retrospective study of a series of 84 patients].

Chronic constrictive pericarditis still poses diagnostic and therapeutic problems. A series of 84 cases (59 men-25 women; men age: 46 years) operated between 1979 and 1989 at the Pitié Hospital was reviewed. The majority of patients (72%) were in functional Classes III or IV; 88% had clinical signs of right ventricular failure and 18% had anasarca. The average duration of symptoms before diagnosis was 20 months. Chest X-ray showed pericardial calcification in 40% of cases. A characteristic dip-plateau pressure tracing was obtained in 76% of cases. A specific aetiology was only found in 36 cases (45%), only 12% being of tuberculous origin. A subtotal pericardectomy from phrenic to phrenic was carried out in 75 patients. The absence of planes of cleavage in 9 cases imposed a special operative technique consisting of "patchwork" sectioning of the visceral pericardium. The operative mortality was 2.3% (2 patients: pulmonary embolism and septicaemia). Non-fatal post-operative complications occurred in 8.2% of cases (7 patients). The survival rate excluding operative mortality was 94% at 3 years and 87% at 7 years. No patient was reoperated for recurrent constrictive pericarditis. At the last follow-up appointment, all patients were in functional Classes I or II. The authors conclude that the absence of specific symptoms, the low prevalence of the condition and the change in aetiology related to the decline in tuberculous infection make the diagnosis of chronic constrictive pericarditis very difficult. The diagnostic contributions of new imaging techniques such as CT and MR scanning should be assessed. This series confirms the efficacy of surgical treatment by subtotal pericardectomy.

Adult↗
PubMed1994

Viability of cryopreserved arterial wall: enzyme-histochemical and physiological markers.

Use of cryopreserved small-caliber arterial allografts for arterial bypass procedures has been suggested. In addition to immunological tolerance, long term in vivo success of these grafts may be dependent on the viability of arterial cells after cryopreservation. Metabolic and functional capabilities of arterial smooth muscle cells were evaluated by studying the enzyme histochemical expressions of sheep carotid arteries after various time of cryopreservation (7 days, 90 to 150 days) and their contractile responses after freezing. The results indicated that cryopreserved arteries exhibited 4 features: (a) the enzyme activities were globally maintained, (b) the spontaneous endogenous oxido-reduction (NitroBT test) was reduced, (c) contractile responses against KCl and norepinephrine were abolished, (d) metabolic status of frozen arteries was independent of the duration of cryopreservation. These data suggest that cryopreserved arterial muscle cells may be depleted in electron donors and/or energy-rich nucleotides substrates. This defect is present after short or long time of cryopreservation.

Animals↗
PubMed1994

[Sorin-Pericarbon pericardial bioprosthesis. A 4-year follow-up study].

Between January 1986 and December 1986, 106 Sorin-Pericarbon (new prostheses made of bobine pericardium) valves were implanted by our group: the object of this paper is to report the medium-term results of this new bioprosthesis. The probability of degeneration-free function at 4 years was 96.5 +/- 3.7% in patients with aortic valve replacement; the probability of reoperation-free survival for all patients was 95.2 +/- 3.3% and 96.5 +/- 3.7% for patients with aortic valve replacement with this prosthesis. The results of this new Sorin-Pericarbon bioprosthesis at medium-term are satisfactory and need to be confirmed at long-term by further follow-up.

Adolescent↗
PubMed1994

Chronic disease of the ascending aorta. Surgical treatment and long-term results.

Between January 1979 and December 1991, we operated on 339 patients for chronic disease of the ascending aorta. The operation was elective in all. Endocarditis and its sequelae have been excluded. Thirty-one patients had a previous operation on the ascending aorta or the aortic valve; 268 patients had aneurysms of the ascending aorta without dissection; 72 had chronic aortic dissections, of whom 33 had a preexistent aneurysm. The patients included 272 men and 67 women. Mean age was 53.58 +/- 7 years. Eight percent of the patients had clinical stigmata of Marfan's disease. A tubular graft replacement was used in 7 patients, a tubular graft and valve replacement in 72 patients, and a composite valve graft replacement with reattachment of the coronary arteries using a 8 mm Dacron graft was performed in 260 patients. Concomitant procedures were used in 74 patients: coronary artery bypass grafts in 25, mitral valve replacement in 9, and aortic arch reconstruction in 40. The 30-day mortality rate was 7.6% (n = 26). For the whole group, multivariate analysis using stepwise logistic regression showed that operative risk factors were concomitant coronary artery bypass grafting, age (increased), aortic valve regurgitation, and previous cardiac surgery. Follow-up was conducted in 303 patients, and risk factors for late mortality were studied. Long-term survival was 59.6% +/- 3.7% at 9 years. It was 67% +/- 3.5% at 9 years for patients without aortic arch reconstruction and 56% +/- 4.5% for patients with aortic arch reconstruction (p = 0.0018). Reoperation was needed in 14 patients. Actuarial freedom from reoperation was 90% +/- 0.2% at 9 years for all the patients. Only one patient with composite valve graft replacement and reattachment of the coronary arteries had required reoperation for problems related to this procedure. This technique is used routinely by our team, especially in patients with large chronic aneurysms, dissected or not, and in those who had previous operations. The long-term results are good.

Aortic Dissection↗
PubMed1993

Results of subtotal pericardiectomy for constrictive pericarditis.

The operative approach to constrictive pericarditis still remains a surgical challenge. Subtotal pericardiectomy through median sternotomy was analyzed retrospectively in a series of 84 patients operated on for chronic constrictive pericarditis at our institution between 1979 and 1989. The mean duration of symptoms prior to diagnosis was 20 +/- 6 months (1-264 months). Preoperatively, 72% of patients were in NYHA class III or IV, presented signs of right cardiac failure (88%) or anasarca (18%). Chest X-ray showed pericardial calcifications in 40% of the patients. Echocardiography revealed pericardial thickening in 62%. Among 62 patients in whom cardiac catheterization was performed, a characteristic dip-and-plateau was found in 47 patients (76%). A specific etiologic factor was identified in only 37 patients: tuberculosis (12%), recurrent acute pericarditis (9%), hemopericardium (9%), radiotherapy (5%), previous cardiac surgery (4%), bacterial infection (2%), myocardial infarction (2%) and connective tissue disease (2%). In 47 patients (55%), the constrictive pericarditis remained idiopathic. In seven patients we performed a redo-operation for previous incomplete pericardiectomy. Subtotal pericardiectomy (from phrenic nerve to phrenic nerve) was performed in 75 patients. A palliative procedure consisting of pericardial "meshing" was performed in nine patients due to an unsatisfactory cleavage plane. Cardiopulmonary bypass was used in four patients for coexistent cardiac lesions. The operative mortality was 2.3% (two patients: septicemia and pulmonary embolism). Seven patients (8.2%) developed early on-lethal complications. The probability of survival for patients discharged for the hospital was 94% at 3 years and 87% at 7 years. There were four late deaths and no reoperation for recurrent constriction.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiopulmonary Bypass↗
PubMed1993

[Endothelin: the vasoconstrictor of the 1990's?].

Endothelin is a recently isolated 21 amino acid peptide with vasoconstrictor activity. It seems to be part of the "hormonal" production by the vascular endothelium and might play a key role in the regulation of vasomotricity. The principal property of endothelin is that it induces an intense and prolonged arterial and venous contraction. Endothelin is secreted by endothelial cells under the influence of various stimuli (thrombin, adrenaline, shearing stress, hypoxia, etc.), then binds to specific membrane receptors thereby increasing the intracellular free calcium concentration. Endothelin has many other vascular and extravascular properties: it has positive inotropic and chronotropic effects, increases renal vascular resistances and reduces the glomerular filtration rate, contracts bronchial and gastrointestinal smooth muscle, induces proliferation of the vascular smooth muscle cells as well as that of fibroblasts and glomerular mesangial cells. Compared with experimental data in animals, human data are still scantly. Plasma endothelin concentration rises in acute renal failure and in chronic renal failure treated by dialysis, diabetes mellitus, essential arterial hypertension, pre-eclampsia and asthma. The development of specific antagonists and endothelin in synthesis inhibitors should soon enable us to specify the modes of regulation of endothelin production before considering applications to therapy.

Animals↗
PubMed1993

Five-year experience with the Medtronic Hall prosthesis in isolated aortic valve replacement.

We reviewed clinical data in 216 patients who underwent isolated aortic valve replacement with the Medtronic Hall prosthesis. Between January 1983 and December 1990, a total of 216 prosthetic valves were implanted in 180 males and 36 females. Preoperatively, 45.5% of patients were in New York Heart Association (NYHA) Class III to IV. Cumulative follow-up was 682 years, and 3.2% of patients were lost to follow-up. The actuarial 5-year survival rate was 90% for the whole group. All the patients were anticoagulated with aceno-coumarol (Sintrom). There were no cases of structural dysfunction and one patient presented with valve thrombosis. The Medtronic Hall valve has a low rate of thromboembolic events without structural failure. It is an excellent device for aortic valve replacement.

Adolescent↗
PubMed1993

[Tricuspid valve replacements in adults. Long-term results].

In the period between January 1979 and January 1989, 72 patients (46 women and 26 men, average age 46 years) out of 697 patients undergoing a tricuspid valve procedure, underwent prosthetic valve replacement for organic tricuspid valve disease. Sixteen patients had pure tricuspid regurgitation (Group I). The causal pathology was essentially traumatic (6 cases) and infections (endocarditis) (5 cases). Fifty-six patients (Group II) had organic tricuspid valve disease associated with a left-heart valvular lesion. The causal pathology was rheumatic fever in 52 cases and endocarditis in 4 cases. In 40 patients (71.5%) the procedure was a reoperation of a mitral and/or aortic and/or tricuspid valve prosthesis. In 21 cases, the initial operation had involved the tricuspid valve. All patients in Group I underwent valvular replacement with a bioprosthesis. In Group II, 40 patients were implanted with a bioprosthesis and 16 with a mechanical valve prosthesis. The follow-up was complete for an average period of 7 years (range 2 to 12 years) for a total of 295 patient-year. The hospital mortality was nil in patients with isolated tricuspid valve disease. Reoperation for deterioration of a porcine bioprosthesis was required after 4 years in 1 case. Terminal cardiac failure was responsible for one late death 7 years after surgery. The hospital mortality was 26.7% (15 patients) in Group II. The actuarial rate of patients free of reoperation at 7 years was 80 +/- 8%. The actual rate of patients free of any prosthetic valve related complication was 78 +/- 2%. The 7 year survival rate excluding operative mortality was 65 +/- 8%.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗