Potentiation by acetylcholine of the effects of a calcium channel activator, Bay k 8644, on dog atria in situ.

The effects of Bay k 8644 were studied in the canine in situ heart under vagal influence and out of this influence on sinus rate and sinus recovery time, conduction time and effective refractory period (ERP) in the atrioventricular (AV) node and ERP of the atrial muscle. Bay k 8644, intravenously infused at the 2 micrograms X kg-1 X min-1 rate for 30 min, enhanced the inhibition of the atrial specialized tissue as well as the shortening of the atrial muscle ERP during vagal activity, elicited by the injection of dextromoramide into the cisterna magna. It did not develop any atrial action in the absence of vagal activity, suppressed by atropine. The reflex increase of vagal tone, in response to a small increase in blood pressure produced by Bay k 8644, is not the only cause of the phenomena observed in the former case. The observations can be explained primarily in terms of an interaction between Bay k 8644 and acetylcholine (ACh):ACh intraaortically injected near the coronary ostia, in a dose just sufficient to slow down sinus rate before Bay k 8644, reduced the rate by 50% at the end of a 60 min infusion of Bay k 8644 and the ACh threshold dose necessary to elicit a short third degree AV block before Bay k 8644 was reduced by 50% at the end of a 30 min infusion of Bay k 8644. Therefore, ACh appeared to be capable of enhancing the effects of a calcium channel activator as well as the effects of hypercalcaemia, as earlier reported.

Role of calcium in the rate-dependent depression of atrioventricular nodal conduction in the dog heart under vagal influence.

Increase in heart rate may be detrimental to atrioventricular conduction. The effects of such an increase were investigated in the paced intact dog heart, by measuring the conduction time in the atrioventricular node (obtained from the His bundle potential recording) and the effective refractory period in this node as determined by the extrastimulus method. Investigations on atrioventricular nodal conduction were performed with and without vagal influence. After central restoration of vagal tone by dextromoramide in anesthetized animals, both parameters appeared to lengthen as the heart rate rose. This lengthening became considerable at the highest rates. After blockade of cholinergic receptors by atropine, no significant change occurred when the heart rate was raised. The prolongation observed under vagal tone was enhanced by the rise in the plasma calcium concentration to 3.10 mmol X l-1 and reduced by a calcium influx inhibitor, verapamil, in 0.2 mg X kg-1 dose. These effects are related to the calcium intracellular concentration, since the rise in this concentration beyond an optimum has been demonstrated to inhibit the calcium and potassium channel.

[Cardiogenic shock complicating extensive infarction with ventricular septal defect. Circulatory assistance and heart transplantation]. / Choc cardiogénique sur infarctus étendu, compliqué d'une communication interventriculaire. Assistance circulatoire et greffe cardiaque.

A 47 year old man had a massive anterior myocardial infarction with cardiogenic shock with a left parasternal murmur. Coronary angiography showed occlusion of the left anterior descending artery for which angioplasty resulted in failure. There was antero-lateral-apical akinesia and a ventricular septal defect (VSD) with a left-right shunt (Qp/Qs = 1.54). Persistence and aggravation of haemodynamic instability led to intra-aortic balloon pumping with inotropic pharmacological support followed by biventricular assistance with a MEDOS device. Under transoesophageal echocardiographic monitoring, the outcome was marked over 7 days by the progressive increase in the shunt volume of the VSD, a decrease of drainage and injection flow, progressive increase in spontaneous contrast echos followed by the presence of fibrin in the cardiac chambers and canulae, the presence of thrombus in the external ventricles, blockage of the right external valve which only opened after increasing the degree of anticoagulation, and, finally, cardiac tamponade which required drainage before the patient's state improved. On the 8th day, the patient being stable with a normal neurological status, the availability of a donor heart led to the decision to transplant, which was carried out without complications. This case poses the problem of cardiac assist devices and their daily monitoring, and then that of cardiac transplantation in this indication.

[Long-term hemodynamic function of the transplanted heart]. / Fonction hémodynamique du coeur transplanté à long terme.

The aim of this study was to identify the long-term haemodynamic changes of the transplanted heart. Between 1987 and 1997, 136 patients required cardiac transplantation at Dijon hospital. During follow-up, 76 patients aged 51.2 +/- 9.46 years underwent catheter studies (12 women, 15.8%; and 64 men, 84.2%). Right and left heart catheterisation was performed at 3 months, 1, 2, 3 and 5 years after transplantation. Right heart catheterisation included measurement of mean pulmonary artery and pulmonary capillary pressures and pulmonary arteriolar resistances. During left heart catheterisation, cardiac output, mean aortic pressure, the ejection fraction, the dp/dt max of the left ventricular wall, systemic arterial resistances and left ventricular end diastolic pressures were measured. At each catheter study, the indexed myocardial mass, indexed end systolic and end diastolic left ventricular volumes, the mass/volume ratio, the residual serum cyclosporine concentrations and the serum creatinine were analysed. In addition, an endomyocardial biopsy was also performed. Initially raised, the mean pulmonary artery and pulmonary capillary pressures decrease from the 3rd month to the 2nd year. From the 3rd year onwards, they readjust to the upper limits of normal. The pulmonary artery resistances underwent the same changes. The left heart parameters remained constant over the period of follow-up but with a heart rate, mean aortic pressure and left ventricular end diastolic pressure higher than normal. The indexed myocardial mass was increased at all periods. The indexed left ventricular end systolic and diastolic volumes decreased with a M/V ratio which increased. Cyclosporine concentrations decreased whereas serum creatinine increased. The frequency of severe rejection and of coronary atherosclerosis was low. Significant correlations were observed between different parameters at different periods. In the long-term, the function of the transplanted heart is not normal in the strict sense of the term. The apparent normality is obtained by anti-hypertensive treatment. The transplanted heart adapts to the increase in cyclosporine-induced afterload by permanent myocardial hypertrophy, and increased diastolic pressure probably relates to diastolic dysfunction without noticeable intracardiac fibrosis.

[Peritoneal dialysis in the treatment of the low cardiac output after extracorporeal circulation]. / La dialyse péritonéale dans le traitement du bas-débit cardiaque après CEC.

Low cardiac output after cardiopulmonary bypass is not uncommon. This per- and postoperative cardiac depression is accompanied by an impairment of renal function, which recovers with the improvement of the low cardiac output. These two correlated failures may become resistant to cardiotonic and diuretic drugs. Indeed the fluid balance is strongly disturbed, although venous pressure is only moderately increased. The only possible treatment could be water withdrawal. Nine patients are reported, all suffering from cardiac and renal failure after cardiopulmonary bypass. They were successfully treated with the method of continuous ambulatory peritoneal dialysis. This method allowed us to stop all intravenous cardiac drugs within 36 h, whilst diuresis reappeared together with a better efficacy of diuretic drugs. This beneficial haemodynamic effect of water withdrawal is discussed. This phenomenon may be related to an influence of right ventricular filling on the left ventricle. Low cardiac output may occur as a result of septal displacement, especially if there is concomitant myocardial suffering. Withdrawing a small volume of water may have modified the septal displacement, and improved cardiac output. Continuous ambulatory peritoneal dialysis was simple and well tolerated; it seemed to have contributed to the haemodynamic recovery of all the nine patients.

[Ten-year experience with heart transplantation (1987-1997)]. / Bilan de dix années de transplantation cardiaque (1987-1997).

OBJECTIVES: Analyze ten years experience with heart transplantation at the Dijon University Hospital and determine which parameters control mid and long term outcome. PATIENTS AND METHODS: One hundred thirty six heart transplantations were performed over a 10 year period (1987-1997) in 118 men and 18 women aged 51-87 years. Heart transplantation was indicated on the basis of the following criteria: ejection fraction *20%, pulmonary arteriole resistance < 6 Wood units, peak oxygen uptake < 14 l/kg/min. The Shumway or anatomic technique was used. The triple immunosuppressive protocol combined corticosteroids, azathioprine and cyclosporin. The same team conducted the post-transplantation follow-up with regular programmed consultations in addition to those requested by the general practitioner, the cardiologist or the patient. Follow-up was oriented according to the clinical situation (blood chemistry, cell counts, cyclosporinemia, search for infection, echocardiography, endomyocardial biopsy, coronarography). RESULTS: Five patients (3.6%) died when still on the waiting list. Absolute emergency transplantation was performed for patients (28.1%) including 8 (5.9%) after circulatory assist. Hospital mortality was 11.7% and late mortality was 16.1%. Actuarial survival was 78% at 1 year, 71% at 5 years and 69% at 10 years. Among the survivors, 94% were taking two, three or even four drugs for hypertension. Cyclosporin levels decreased and creatinine levels increased. Episodes of rejection were minimal: 86.57% of the biopsies were * grade 1 and 4.45% * grade 2. Cytomegalovirus infection was documented and treated in 7.55% of the cases. Incidence of graft coronary artery disease was 3.4% at 1 year, 6.5% at 2 years and 7.9% at 3 years. CONCLUSION: Our follow-up structure where the same small team conducts regular examinations together with our approach to heart transplantation appears to be the main factor leading to the quality results obtained in this series.

An approach for integrating heterogeneous information sources in a medical data warehouse.

In recent years, medical professionals are witnessing an explosive growth in data collected by various organizations and institutions. At the same time, the ongoing developments of networking technologies provide doctor with the capability to access these data across the boundaries of interconnected computers. In this paper we present a medical data warehousing methodology that aims to use data semantics to regroup and merge patients' medical data from different health information systems, which may be autonomous and heterogeneous. The proposed solution takes into account European laws concerning the security and anonymity of personal data.