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Biomedical subjects

D Loisance

Publications and source records attributed to D Loisance.

At least 127 records · Page 7Linked to original sources
PubMed1990

Onset and development of cyclosporin A effects on lymphocytes of cardiac patients before heart transplantation.

The effects of cyclosporin A (CSA) in low dosage (4 mg/kg/24 h i.v.) were studied in 17 patients awaiting heart transplantation. The lymphocyte subsets were typed, enumerated, and their proliferation measured before CSA perfusion, after infusion (over 24 h), and then again after two further 24 h intervals (T0 h, T24 h, T48 h, and T72 h). No significant change was found in T or B enumerations although lymphocyte function was markedly modified. For all 17 patients, there was a significant decrease in lymphocyte proliferation that was, however, re-established after 72 h for 14 of the patients, but not for the remaining 3. Inhibition of the proliferative response was found to occur rapidly, to be potent although rapidly reversible in most cases, while yet subject to wide interindividual variability. These four features suggest that (a) CSA in fixed doses may later the balance between helper and suppressor cells in varying degrees according to the patient, and that (b) CSA given immediately or shortly after heart transplantation could be beneficial.

Adult↗
PubMed1990

Recovery of a normal coronary vascular reserve after rejection therapy in acute human cardiac allograft rejection.

During acute rejection, coronary vascular reserve is severely impaired in human orthotopic heart transplants. To evaluate the effects of rejection therapy on coronary vascular reserve, the ratio of peak-to-resting coronary flow velocity was assessed with a coronary Doppler catheter and a maximally vasodilating dose of intracoronary papaverine (12 mg) in nine allograft recipients without rejection (group 1) and in six recipients before and after treatment of an acute episode of rejection (group 2). All the patients had normal epicardial coronary arteries and were free of left ventricular hypertrophy. In group 2 during rejection, the coronary vascular reserve was significantly lower than in group 1, in which all the patients had a peak-to-resting coronary flow velocity ratio greater than 4 (2.3 +/- 0.5 vs. 5.4 +/- 0.8, respectively, p less than 0.001). In group 2 after treatment of rejection, the peak-to-resting coronary flow velocity ratio was similar to that of group 1 (4.7 +/- 0.8). Heart rate, left ventricular volumes and pressures, hemoglobin concentration, and arterial oxygen pressure were similar in the two groups. This study provides evidence that alterations of coronary vascular reserve because of acute rejection were reversible after treatment of the rejection episode.

Angiography↗
PubMed1990

[Experimental study of arterial microanastomoses under tension in the Wistar rat. Morphologic and histologic effects].

An experimental study was performed to evaluate the effects of tension on microsurgical anastomoses. A variable length of the common carotid artery in Wistar rats was resected to give variable degrees of tension and the artery was reanastomosed microsurgically. 42 Wistar rats were divided into 7 groups of 6 rats each according to the relative length resected. Repaired arteries were then compared histologically and functionally with the artery of the contralateral side, submitted to simple section followed by microsurgical anastomosis. Significant histological changes occurred when the length of the resected segment was greater than 13.33% of the vessel's total length. These changes included subendothelial hyperplasia, medial necrosis and thrombosis. The results of this study lead us to conclude that small degrees of tension (less than 13.33% of total vessel length in this study), have no significant effects on patency of microanastomoses. Greater tension results in changes in the laminar flow through vessels that can adversely effect patency. There are also significant histological changes that may have detrimental effects in the long term.

Anastomosis, Surgical↗
PubMed1990

[Myocardial mass index in the diagnosis of acute rejection of allogeneic heart transplants].

Changes in an index of left ventricular mass were evaluated in the diagnosis of acute cardiac transplant rejection in a prospective study involving 28 transplant patients by comparison with the histology of endomyocardial biopsy. The surface of a ring of left ventricular myocardium obtained from a 2D echocardiographic examination was used as an index of mass. Eighty-three pairs of results--biopsy and index of mass--recorded within a 12 hour interval were obtained between the first day and 10th month of transplantation over a period of 12 consecutive months. Echocardiographic diagnosis of acute rejection was made when the index of myocardial mass increased by over 7 per cent compared with baseline values recorded during the first 3 days of transplantation or during a new period of equilibrium after an episode of rejection. Two groups of patients were identified from the results of biopsy, taken as the reference: in 16 patients with mild or moderate histological signs of rejection the variation of the index of mass was 18.3 +/- 9.1%; endomyocardial biopsy was negative in the 12 other patients and the change in index of mass was -1.5 +/- 5.2% (p less than 0.001). The overall concordance in the 83 successive results was good with a Kappa coefficient of 0.71. The other parameters which have been reported to be useful in diagnosing rejection (relaxation, antegrade diastolic mitral flow, acoustic density of myocardium) present a number of problems in routine practice related either to difficulties with the recording of the data or to its interpretation.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1990

[Cardiac transplantation. Indications, delays, surveillance].

The number cardiac transplantation has been dramatically increasing for the last year and the results are satisfactory regarding survival or functional capacity. The observed increase of cardiac transplantation may tend to vulgarize it. However, this intervention should be only considered in a selected group of patients who have no other option. Many reports concerned various technical approach for a clearcut determination of high and low risk population of patients with congestive heart failure. But, considering individual patients, the value of each prognostic parameter remains unresolved. Nevertheless the more discriminant parameters for the prognosis assessment are: the left ventricular ejection fraction, the NYHA class, right heart catheterization data, the functional capacity, the cardiothoracic ratio on chest X ray, the ischemic etiology of the disease. The role of neuro-hormonal determinant such as norepinephrine circulating concentration or cardiac uptake on MIBG imaging should be further investigated, especially for patients treated by ACE inhibitors or beta blockers. Contraindications for cardiac transplantation are less restrictive, nowadays. Concerning patients selected, and waiting for heart transplantation or patients non primary selected survival can be improved by adjusting medical therapy on objective efficacy criteria.

Contraindications↗
PubMed1990

[The intracardial hemopump. A new technique of left ventricle assist device].

A new left ventricular assist device consisting of a canula containing a turbine introduced by retrograde catheterisation was evaluated in the prevention of complications in 9 patients undergoing high risk coronary angioplasty. The good clinical and hemodynamic status during and after coronary dilatation confirmed the system's innocuity and its efficacy each time it could be correctly positioned in the ventricle (6 patients). These extremely encouraging preliminary results suggest that an additional simplification but reducing the size of the canula and increasing turbine flow, allowing percutaneously introduction would constitute a significant development.

Aged↗
PubMed1990

[Medical strategy in patients awaiting emergency heart transplantation].

Cardiac transplantation is theoretically the optimal final treatment of terminal cardiac failure but the indications, especially in the emergency situation, should be carefully considered. Sympathomimetic agents are of limited use in patients with severe cardiac failure partly because of the down regulation of the myocardial beta-receptors. The phosphodiesterase inhibitors, represented by enoximone, are valuable because of their action on the cardiac muscle (inotropic and lusitropic) and their direct systemic vasodilator effect. Enoximone can be administered by intravenous bolus resulting in a rapid onset of action (peak at 30 minutes) with a prolonged effect due to its hepatic metabolites. The authors' experience in this indication dates over 5 years and over 50 patients were included. A preliminary study in 34 patients with cardiac failure resistant to betamimetic drugs, referred to the intensive care unit for urgent cardiac transplantation, or, in the absence of a donor, circulatory assistance is reported. A Swan Ganz catheter and radial artery canula were inserted for haemodynamic monitoring and enoximone was administered in an intravenous bolus over 15 minutes every 8 hours in addition to sympathomimetic agents. A haemodynamic improvement was observed after the 30th minute in 30 patients. The cardiac index increased from 1.82 to 2.67 l/mn/m2 and the pulmonary capillary pressures decreased from 30.8 to 18.9 mmHg. Systemic arterial resistances fell from 2,170 to 1,520 dynes.s.cm-5. No haemodynamic improvement was observed in 4 patients who were treated by mechanical ventricular assistance. After investigations to detect contra-indications to cardiac transplantation, 12 of the 30 patients remained candidates for cardiac transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Use of brachial venous grafts in coronary bypass surgery].

From May, 1975, to December, 1988, 30 patients (pts), 26 men and 4 women, aged 36 to 79 (average age: 58) underwent one or several aortocoronary bypass (ACB) operations requiring the use of veins from the upper limbs (VUL). Sixty operations (2.0 ACB/pt) were performed, involving the anterior interventricular artery in 27 cases, the right coronary artery in 14 and the other left vessels in 19. The grafts used were a VUL in 45 cases, an internal mammary artery in 13, a great saphenous vein in one case and a 4-mm polyurethan tube in one case. The indications for the use of a VUL included bilateral stripping in 23 patients, repeated phlebitis in one, bilateral varices in 2, and the previous use of the saphenous veins in 4 patients. The coronary lesions were a three-vessel involvement in 17 cases, a two-vessel involvement in 9 and a single-vessel involvement in 4. An additional procedure was required in two patients for the resection of a left ventricular aneurysm and for the plication of an akinetic area of the left ventricle. No intraoperative complication was observed. Perioperative mortality was of two cases (6.6%). The postoperative myocardial infarction rate was of one case (3.3%). A complication directly associated with the type of graft used (massive bleeding due to graft tearing) caused cardiac arrest in one case. Two patients presented with local disorders caused by the removal of veins from the upper limbs, including hypoesthesia of the forearm in one case and anesthesia associated with regressive muscle enfeeblement in the other.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1989

Maximal coronary vasodilator capacity of orthotopic heart transplants in patients with and without rejection.

In cardiac allograft rejection, histopathologic changes suggesting that myocardial ischemia is a component of the rejection process have been documented. To further define the coronary vascular reactivity of human heart transplant, coronary sinus blood flow and coronary resistance were measured before and after intravenous dipyridamole within the first year after transplantation in 8 patients without rejection (group II) and in 5 patients with rejection (group III). All had normal coronary arteriograms. Results were compared to those of 8 control subjects (group I). After dipyridamole, coronary sinus blood flow was increased in groups I, II and III by 303, 212 (p less than 0.01 vs group I) and 45%, respectively (p less than 0.001 vs groups I and II). Coronary resistance was reduced by 77, 73 (not significant vs group I) and 36%, respectively (p less than 0.001 vs groups I and II). Concomitantly, coronary sinus blood oxygen content was increased by 172, 145 (not significant vs group I) and 78%, respectively (p less than 0.001 vs group I, not significant vs group II). Thus, the coronary flow reserve evaluated by the dipyridamole/basal coronary sinus blood flow ratio and the coronary resistance reserve evaluated by the basal/dipyridamole coronary resistance ratio were dramatically impaired in group III (1.56 +/- 0.09 and 1.63 +/- 0.30, respectively, p less than 0.001 vs groups I and II). In contrast, they were almost normal in group II (3.11 +/- 0.42 vs 4.03 +/- 0.52 in group I, p less than 0.02, and 3.83 +/- 0.78 vs 4.45 +/- 0.81 in group I, difference not significant). Thus, the impairment of coronary reserve during heart rejection should be linked to abnormalities of the coronary microvaculature. This emphasizes the important involvement of the coronary circulation in the rejection process.

Adult↗
PubMed1989

Pharmacological bridge to cardiac transplantation.

From September 1985 to August 1988, 32 patients were referred from various intensive care units throughout Paris for urgent cardiac transplantation or for a mechanical bridge to transplantation. At time of admission, under maximal sympathomimetic therapy, the cardiac index (CI) was 1.81 +/- 0.26 l/min per m2, the pulmonary capillary wedge pressure (PCWP 31 +/- 7 mmHg), systemic vascular resistances (SVR) 2053 +/- 469 dynes s cm-5. In 25, diuresis was less than 25 ml/h. Five were anuric. Prior to any final decision, a new inotropic agent, enoximone, was infused in addition to previous treatment as a 10 min bolus iv 1.5-2 mg/kg every 8 h. In 3, the situation further deteriorated, leading to a Jarvik 7-70 implantation within 12 h. In 29 however, within 3 h, the Cl increased to 2.69 +/- 0.56 as SVR dropped to 1410 +/- 453 and PCWP to 18 +/- 7. Diuresis increased to more than 100 ml/h in all. This permitted an indepth evaluation of the transplant candidates leading to contraindications to transplantation in 16. Nine patients could be weaned off iv enoximone. Four of these are still living (NYHA class III) with a follow up of 6-17 months. In 11, transplantation was performed within 2 days. Four died within a month, 2 with multiple organ failure. One patient died after 5 months. Six are back to normal life, NYHA class I (follow up 10 months-2.5 years). This protocol suggests that in patients with extreme heart failure, immediate survival may be increased by iv enoximone therapy, permitting a better selection of the recipients, more efficient pre-transplantation intensive care and consequently a decrease in the indications for a temporary mechanical bridge to a staged transplantation.

Adenosine Monophosphate↗
PubMed1989

Combined heart and kidney transplantation using the same donor.

A 45-year-old man received a combined heart and kidney transplant provided by the same donor. The patient was in the terminal stage of renal failure and was submitted to 3 sessions of haemodialysis per week for 2 years before transplantation. A dilated cardiomyopathy with severe impairment of left ventricular (LV) function was discovered, precluding renal transplantation alone. In the postoperative course, a cardiac rejection episode was detected by echocardiography and documented by endomyocardial biopsy; no simultaneous rejection of the kidney could be detected. The patient was discharged after 2 months, and he resumed a normal and active life. The specific problems raised by the management of such multi-organ transplantation are briefly reviewed.

Cardiomyopathy, Dilated↗
PubMed1989

Severe impairment of coronary reserve during rejection in patients with orthotopic heart transplant.

The present study analyzed coronary sinus blood flow alterations after dipyridamole induced coronary vasodilation in seven patients whose endomyocardial biopsies evidenced no sign of rejection (group 1) and in five patients with histologic signs of rejection (group 2) after orthotopic heart transplantation. All patients were treated with cyclosporine and prednisone and some with azathioprine and had normal coronary arteriograms. Coronary sinus blood flow and coronary resistance were measured before and after intravenous dipyridamole (0.18 mg/kg/min over 4 minutes). Basal values were similar in groups 1 and 2 for coronary sinus blood flow (166 +/- 34 compared with 181 +/- 39 ml/min, respectively), coronary resistance (0.62 +/- 10 compared with 0.52 +/- 13 mm Hg/ml/min, respectively), coronary sinus blood oxygen content (5.7 +/- 1.6 compared with 4.5 +/- 0.9 ml/100 ml, respectively) and arterial-coronary sinus blood oxygen difference (10.6 +/- 1.3 compared with 10.3 +/- 1.8 ml/100 ml, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1989

[Dose-dependent vasodilator effect of dobutamine in calves with a constant cardiac output artificial heart].

The haemodynamic effect of any drug being the resultant of its myocardial and vascular actions, it is often difficult to separate what is due to each of these components. Dobutamine is regarded as having an almost exclusive effect on the myocardium in therapeutic doses (1); its administration after implantation of an artificial heart would enable its peripheral vascular effects to be determined by exclusion of the native ventricles. Experiments were conducted on three calves weighing about 90 kg each. The artificial heart, two central venous catheters and a femoral arterial catheter were implanted under general anaesthesia. The study began on the first post-implantation day, the animals being awake, in stable haemodynamic status and with normal temperature. Dobutamine was infused through one of the venous catheter placed in the native atrium, in 6 stepwise doses of 5, 10, 15, 20, 25 and 30 mcg/kg/min, each dose being given over 10 min and separated from the other dose by a 10 min interval. The order in which these doses were administered was determined at random. By adjusting the propulsion pressure of the two ventricles and the heart rate, the cardiac output was set at a fixed value of 7.85 L/min throughout the study, this value being controlled by a computer-assisted unit. Right atrial pressure and femoral arterial were recorded during each step of the infusion. Total peripheral resistance was calculated over a stable period of the last 5 min of each dosing and before administration of dobutamine. This procedure was repeated 4 times in each calf, at intervals of 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[The artificial heart. Current experiences].

Various assistance or replacement systems, usually including pneumatic pumps, are now used in human medicine to treat irreversible shocks. These systems are still very far from the ideal artificial heart, but they enable the ventricular work to be partially or totally achieved for a limited length of time, thus ensuring the patient's survival pending heart transplantation. The two systems most frequently used nowadays, i.e. orthotopic ventricular prosthesis or "internal artificial heart" and ventricular shunt or "external artificial heart" are described. The clinical experience available provides a first evaluation of the true performance of these systems.

Heart, Artificial↗
PubMed1989

Centrifugal pump or pneumatic ventricle for short-term mechanical circulatory support?

Two comparable groups of four Holstein calves were implanted with different left ventricle assist devices: the Centrimed centrifugal pump (CP) (Sarns Inc.) or the UTAH 85 VAD pneumatic ventricle (University of Utah). Operative procedure, inflow and outflow cannulae, monitoring, heparinization, were identical in both groups. No transfusion was ever required. The study was terminated after three days and autopsy was performed on the calves. Left ventricular unloading provided by both devices was complete (LVEDP less than 1 mmHg) and identical. LV bypassed flow rate was higher in CP (0.045 L/min/kg) than in UTAH 85 VAD (0.035 L/min/kg) but with no statistical difference. Blood trauma was comparable in the two groups. Daily blood samples did not show any significant changes from baseline values in creatinine, hematocrit, fibrinogen. Platelet loss from initial level was 30%; serum lactate dehydrogenase rose 150% with no significant difference in the two groups; plasma free hemoglobin never reached significant values. At autopsy, thrombotic deposits on cannuale and renal infarction rate were similar. CP housing had to be changed every day, whereas no technical failure was ever observed with the UTAH 85 VAD. Clinical response and blood damage of the two pumps used as LVAD were the same. Considering the CP has to be replaced every 24 h, the cost of three CP's would be comparable to one Utah UVAD-85 if polyurethane tricusp semi-lunar valves are used in the latter. Until the UTAH-85 VAD becomes commercially available, simple valveless low-cost CP are very attractive for short-term mechanical support.

Animals↗