Biomedical subjects
Publications and source records attributed to D Loisance.
The implantation of an artificial Jarvik-type artificial heart while awaiting retransplantation raises a technical problem which has not yet been definitively solved. An original technique which consists of preserving the atrial portion of the graft and its vessels is presented and illustrated by a clinical case.
One hundred eighty-eight Mitroflow pericardial valves, implanted on 166 patients from March 1983 to December 1986, have been followed for a total of 4316 patients x months. Mortality rate in the first three postoperative months is approximately 10% related to noncardiac complications. One hundred forty-nine patients are living at the start of the follow up period. During that period, one valve was explanted after 22 months for a cusp tear. The rate of thrombo embolic episode is minimal, six cases, as 47% are free of any anticoagulant therapy. One patient, operated upon for active SBE, required additional surgery 2 months later for a prosthetic infection. The present results suggest that early primary failure of Mitroflow valve is quite unfrequent.
An experimental model of heterotopic intrathoracic cardiac transplantation making possible an evaluation of graft viability and function has been studied. The technique requires only two anastomoses in the normothermic state without cardiopulmonary bypass. In this model, the ascending aorta of the recipient animal may be occluded completely, enabling an increasing preload on the graft. In case of adequate myocardial preservation of the cardiac graft, the aorta may be completely occluded and the recipient systemic circulation can be sustained by the graft. However, in case of inadequate graft myocardial function, or in case of size mismatch, the recipient heart alone contributes to the circulation. This technique appears quite useful because of its simplicity, the elimination of the need for extracorporeal circulation while allowing a functional evaluation following cardiac graft preservation.
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Sixty-one patients with septal rupture immediately consecutive to acute myocardial infarction underwent emergency surgery after a period of intensive care which included diastolic counterpulsation in 25 cases. The operation was performed in 37 patients with controlled haemodynamic status and in 24 patients still in a state of shock. The surgical procedure comprised wide exposure of the lesions, septal reinforcement, closure of the ventricular septal defect, removal of the infarct and correction of associated valve lesions. Thirty-one patients died (7 of them of non-cardiac complications) in the immediate post-operative period. The population of 30 patients who survived was analyzed over a 14-year period. Mean follow-up of the 17 patients now alive was 74.8 months. All are free from major disablement owing to treatment with vasodilators, inotropic drugs and diuretics. None of these patients in suffering from angina. Only one patient developed a serious late complication: a ventricular aneurysm which was operated successfully. The contrast between the extreme seriousness of the initial period and the quality of life of patients who survived the acute stage is emphasized.
The bowel is not always suitable for cystoplasty. The use of a vicryl mesh lined with a peritoneal flap was investigated as material for partial replacement of the bladder. The procedure was performed on 20 rats divided into two groups. A partial cystectomy was first performed, then a cystoplasty was done using either a free peritoneal flap (group 1) or a vicryl mesh combined with a peritoneal flap (group 2). The results were evaluated using intravenous pyelography, macroscopic examination and histological analysis within one month. In group 1 (7 cases), there was one urinary fistula. In group 2 (13 cases), no fistula was observed but stones occurred in three cases. The histological analysis revealed good reconstruction of urothelium in both groups. Partial resorption of vicryl was observed at one month with organization of neo-muscular fibers. The vicryl prosthesis was well accepted and, when covered by a peritoneal flap, provided a strong and water-tight material for bladder replacement. The vicryl mesh increased the risk of stone formation in the presence of urinary tract infection.
The relationship between blood cells and plasma concentrations of cyclosporin A (Cy A) determined by radioimmunoassay, was investigated in 12 heart and 12 kidney transplant recipients. The decision between a linear and nonlinear model was made according to a standardized residuals plot. We observed high blood cells-plasma concentration ratios in the two groups, indicating a high affinity of Cy A for blood cells. The distribution of Cy A between blood cells and plasma was ascribed to a nonlinear saturable model in the two groups. According to our results we have simulated the blood-plasma concentration ratio of Cy A as a function of plasma Cy A concentration and hematocrit.
Bacterial endocarditis of the mitral valve appears to be much less common than bacterial endocarditis of the aortic valve. One of the main etiologic factors is the presence of degenerative lesions of the mitral apparatus, ballooning or mitral floppy valve. The surgical anatomy of the lesions is described: vegetations, perforations, rupture of chordae tendinae, abscess of the mitral ring observed in the isolated mitral endocarditis, mitral-aortic dislocation, abscesses and aneurysms of the mitral-aortic fibrosa and jet lesions on the anterior mitral leaflet. In the isolated primitive mitral infective lesions, all the technical skills are directed toward the prevention of the perivalvular leakage of the prostheses. Special procedures are described for the management of the abscesses of the mitral ring. In patients with mitral-aortic lesions, the main problem is treatment of the dislocation of the annuli or aneurysms of the mitral-aortic fibrosa. Despite technical advances, the surgical prognosis of the mitral endocarditis remains severe. In a personal series, the authors recorded a mortality of 12% in isolated mitral cases and 42% in the combined mitral-aortic patients. Early surgical treatment remains the most significant factor in decreasing the fatality of such lesions.
An original method of myocardial revascularization using CO2 laser has been studied in a pig model with acute myocardial infarction. Transparietal channels were created by myocardial vaporization, using a CO2 laser beam. A comparative evaluation was made against a control group using as parameters survival rate, ECG changes, anatomopathologic findings, and angiographic studies. With the exception of favorable changes in the ECG there was no other evidence of improved regional perfusion. No evidence of long-term patency of the transmyocardial channels could be demonstrated by angiographic and histologic studies.
In a series of 833 operations with implantation of 1011 prosthetic valves there were 64 reoperations on 44 patients, an incidence of 7.6%. In almost 50% of the cases, reoperation was motivated by desinsertion. The incidence of desinsertions increased with the number of reoperations. In 40% of the cases, desinsertion was caused by endocarditis. The degeneration of bioprosthetic valves was rapid in children. Thromboembolic accidents occurred in patients with mitral valve mechanical prosthesis. Peri-operative mortality due to left ventricular dysfunction was 9%. Mortality rate was high after reoperation for endocarditis on a desinserted prosthetic valve. Surveillance and prevention of bacterial endocarditis remain of paramount importance.
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During the 1973-1983 period considerable changes have taken place in the techniques and indications of coronary bypass. In a homogeneous series of 3095 patients operated upon by the same group, changes in techniques have been: the introduction in routine coronary bypass of the membrane oxygenator which provides optimal biological conditions and the prolonged circulatory assistance so necessary to high risk patients, and the application to coronary bypass of microsurgical techniques enabling surgeons to perform multiple anastomoses on small vessels easily and safely. Changes in indications have been characterized by a progressive decrease in operations on patients with one-vessel lesions and normal left ventricular function to the benefit of those with multiple-vessel lesions and altered left ventricular function. As a result, the complete revascularization rate and the number of anastomoses have increased continuously. These two categories of changes have not modified the overall in-patient mortality rate, but there has been a significant increase in peri-operative necrosis.
CO2 laser open endarterectomy of small atherosclerotic vessels appears feasible. Under the conditions described, the endarterectomized arterial wall is not smooth but the thrombogenicity of the laser-treated surface is low, and the endothelial healing rapid. These advantages are to be weighed against the consequence of thermal injury, in particular, the late development of aneurysms. Before human clinical trials are made, further experimental studies are required to determine the best type of laser and optimal wave length to limit thermal injury.
Coronary sinus blood flow and resistance were studied before and after intravenous dipyridamole in 4 patients with transplanted heart and normal coronary arteriogram treated by cyclosporine-prednisolone. Results were compared to those of a normal group of 7 subjects. Left ventricular endomyocardial biopsies were performed in the heart transplanted group. Mean right atrial pressure, cardiac index and left ventricular function were normal in the transplanted heart group. Mean aortic pressure and systemic vascular resistances were significantly higher in the transplanted group than in normals (p less than 0.01), but coronary resistance were similar. Dipyridamole-induced vasodilation resulted in an increased coronary sinus blood flow and a decreased coronary resistance in both groups, but these effects were reduced in 1 patient with a transplanted heart that evidenced an important perivascular fibrosis after a subacute rejection. In conclusion, this preliminary report of coronary blood flow in patients with transplanted heart indicates that the ability of coronary sinus blood flow to increase after dipyridamole is normal in the transplanted heart without allograft rejection. A major limitation in coronary vasodilation was observed in 1 patient with rejection antecedents and perivascular fibrosis, which could play a role in left ventricular function deterioration in some patients after heart transplantation.
The authors propose a simplified technique for the resection of dystrophic aneurysms of the ascending aorta with aortic regurgitation. The technique is based on a special method of shaping the Dacron tube, so that the proximal line of suture extends to the bottom of the sinuses of Valsalva, in front of and behind the coronary ostia. The results in 27 operated patients are reported. The global hospital mortality was nil. Seventy four per cent of patients had no complications at all 22 per cent had minor and rapidly regressive complications. The long-term results were assessed in 20 patients. There were no secondary deaths or reoperations. Angiographic and/or echocardiographic control performed in 12 cases showed no valvular dysfunction or recurrence of the aneurysmal process. The advantages of this technique are its simplicity, its good short and long-term results and the possibility of using a bioprosthesis for aortic valve replacement.
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