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Biomedical subjects

D Loisance

Publications and source records attributed to D Loisance.

At least 181 records · Page 10Linked to original sources
PubMed1980

Biodegradable arterial prosthesis from rat aorta.

The preparation and potential clinical use of biodegradable microarterial grafts from rat aorta were investigated. Trypsin treated arterial segments were coated with heparin or chondroitin sulfate to reduce thrombogenicity. The samples were crosslinked with formaldehyde vapors at 4 degrees C. 50 - 100 microgram glycosaminoglycans taken up per mg aorta dry weight were resistant to washing with water for 24 hrs. The covalent crosslinks introduced by formaldehyde and resistance of the grafts to proteolytic degradation. The treated grafts were implanted on 70 rats in an infrarenal aortic position. The permeability of the aldehyde crosslinked prosthesis after 21 days by patency test was lower than the patency ratio measured with fresh autologous grafts. The glycosaminoglycans associated with the prosthesis improve the patency of the crosslinked grafts by about 48%. The resistance to bacterial collagenase of the excised grafts decreased with progressing time of implantation. In the permeable prosthesis and in the contiguous aorta, elastolytic activity was demonstrated by radial diffusion in elastin-agar gels. The grafts removed after 21 days of implantation were surrounded with scar tissue. In contrast to fresh aorta, the macromolecular hydroxyprolin in the scar was readily solubilized with pepsin. The presence of the fragmented elastin and collagen fibers in the excised graft is in favour of their resorption "in vivo".

Animals↗
PubMed1980

[Towards a non-invasive left-ventricular assisted circulation. Experimental study].

An original system of closed chest direct left ventricular circulatory assistance was assessed in the dog. The system comprises a compact centrifugal pump, a left ventricular cannula for aspiration and an arterial cannula for reinjection of the blood. The cannulae may be introduced by retrograde arterial catheterisation, the first by retrograde transaortic catheterisation and the second positioned in the descending thoracic aorta. This circuit was evaluated in a dog model of acute myocardial infarction involving 39+/-8 p. 100 of left ventricular mass. Mechanical circulatory assistance maintained an extracorporeal output (78+/-5 ml/min/kg) identical to the cardiac output measured immediately beforehand. Left ventricular emptying was complete (LVEDP = -2.3+/-2.5 torr), its external work becoming nil. The pulmonary artery pressure (13.1+/-0.8 torr) and pulmonary artery resistances (311+/-28 dynes/cm.s-5) were significantly lower, whilst no increase in systemic resistance was observed (3 134+/-300 dynes/cm.s-5). During the new haemodynamic equilibrium St segment elevation at the centre and at the edge of the cyanosed myocardium was significantly reduced to (p < 0.05). Irreduceable ventricular fibrillation at coronary artery ligature occurred in two animals. Spontaneous reversion to sinus rhythm was observed when circulatory assistance was started. Termination of left ventricular circulatory assistance after 2 hours was accompanied by a significant (p < 0.005) fall in cardiac index (59+/-7 ml/min/kg), increase in left ventricular filling pressure (LVEDP 7.8+/-1.8 torr), increase in systemic resistance (3 803+/-404 dynes/cm.s-5). The electrical changes of myocardial ischemia worsened (p < 0.005). No valvular or parietal complications of cannulization were observed. This protocol shows the practical value of the original left ventricular circulatory assistance circuit described. The results suggest that a significant reduction of myocardial ischemia due to coronary artery ligature may be achieved by this means. a clinical trial of the value of this extra corporeal circulatory assistance in the treatment of cardiogenic shock is suggested.

Animals↗
PubMed1980

A new method of para-corporeal left ventriculo-aortic bypass.

An original closed chest method of let ventriculo-aortic bypass, using a centrifugal pump, an inflow cannula placed into the ventricle from a peripheral ventrial access in a retrograde fashion, and an outflow aortic cannula have been evaluated on a canine acute model of acute myocardial infarction. The system permits a 100% left ventricular decompression as peripheral perfusion is kept steady. The reduction in the ST segment elevation observed both in the infarcted area and the border zone suggests an improvement in the myocardial energetic balance. The system, because of its simplicity and its efficacy should easily be accepted by cardiologists for the treatment of cardiogenic shock as a complication of acute myocardial infarction.

Animals↗
PubMed1979

[Aorto-coronary venous bypass. The value of microsurgical techniques (author's transl)].

The application of microsurgical techniques to myocardial revascularisation surgery by aorto-coronary venous bypass makes it possible to extend the indications for operation to patients with severe coronary lesions, generally considered to be unsuitable. A technique of vascular suture in two layers combined with a widening angioplasty is described. Their value is illustrated by the blood flow studies and the clinical results in 66 bypass performed on 32 patients.

Coronary Artery Bypass↗
PubMed1979

[Septal rupture after myocardial infarct. Early operation; 31 cases].

31 survivors of a group of 49 patients with septal rupture during acute myocardial infarction were operated on average 8 days after the onset of necrosis. The operation was performed after a period of circulatory assistance in 23 cases and consisted of septal reinforcement, closure of the perforation and resection of necrotic tissue. The results were satisfactory in patients operated on early after effective resuscitation (91 p. 100 survival), and better than in the patients operated on after the maximum possible delay (50 p. 100 survival) and in patients in whom poor tolerance of the VSD led to an emergency salvage operation (29 p. 100 survival).

Aged↗
PubMed1979

[Aortocoronary bypass for the threatened spread of acute myocardial infarction].

21 patients with unstable angina in the acute myocardial infarction period were treated by early surgery, on average on the 3th day after infarction. Resistance to medical therapy given in the coronary care unit, associating modern pharmacological agents and circulatory assistance, on the one hand, and the presence of lesions on the coronary arteries accessible to surgery on the other, were the surgical indications. The absence of operative mortality and of electrical changes after operation seem to be related to the many advances made in the various stages of the medico-surgical management. These results suggest that revascularisation surgery with an acceptable risk may be proposed to patients with unstable angina after a recent myocardial infarction.

Acute Disease↗
PubMed1979

[Embolism in a fragment of the mitral papillary muscle to the left main coronary artery. A rare complication of valve replacement].

A 64-year-old man, who underwent double valve replacement for mitral and aortic incompetence due to infective endocarditis, presented with a coronary embolism of a fragment of mitral papillary muscle in the immediate post-operative period. The diagnosis, suggested by the sudden development of acute myocardial insufficiency during ventricular filling, was confirmed by the absence of clinical or electrical improvement during circulatory assistance and by surgical exploration of the left coronary artery. Complete recovery after embolectomy emphasises the value of the association of circulatory assistance and immediate myocardial revascularisation.

Aortic Valve↗
PubMed1979

[Acute early mitral insufficiency following myocardial infarction].

Five cases of acute mitral incompetence complicating myocardial infarction at an early stage underwent early mitral valve replacement. The surgical indications were deterioration of the clinical and haemodynamic conditions or dependance on medical therapy and intra-aortic balloon pumping. The mitral lesion was haemorrhagic necrosis of the posterior papillary muscle in all cases, associated with rupture of the chordae or papillary muscle in 3 cases. The outcome was favourable in all cases and has been maintained after more than two years post operative follow-up. The problems of the surgical indications, the mitral valve replacement and coronary revascularisation are discussed.

Acute Disease↗
PubMed1979

[Experimental study of left ventricular assistance].

An experimental study, on normal dog and a model of cardiogenic shock, using an extracorporeal circuit including 2 cannulae and a centrifugal pump, has shown the superiority of the ventriculo-aortic bypass on the atrio-aortic bypass, for a complete left ventricular mechanical assistance.

Animals↗
PubMed1979

[Membrane oxygenator in cardiac surgery. Its interest in extra-corporal circulation (E.C.C.) lasting more than three hours (author's transl)].

Retrospective analysis of 20 cases of heart surgery under extracorporeal circulation lasting more than three hours was performed to assess the foreseeable character or not of the long duration of the E.C.C., furthermore the risk and interest of prolongation of the E.C.C. when the latter is performed with a membrane oxygenator. It is difficult to foresee before the operation the onset of problems of operative technic which lengthen the duration of the operation, and the necessity to continue the perfusion owing to the impossibility of stopping the E.C.C. The minimal risk of prolonging the E.C.C. when the latter is equipped with a membrane oxygenator and when the operative difficulties are solved satisfactorily leads one to consider E.C.C. an essential factor in intensive care.

Adolescent↗
PubMed1978

[Posterior septal rupture occurring early following myocardial infarction. Surgical repair (author's transl)].

The particular anatomical features of posterior septal ruptures necessitate an adaptation of the technique used in the repair of anterior lesions. The repair may be performed either via a right transventricular approach or via a left transventricular approach, the choice being guided by the topography of the parietal lesions of myocardial necrosis and by the existence and type of associated valvular lesions.

Acute Disease↗