Slow inward current in single cells isolated from adult human ventricles.

Characteristics of the slow inward current (Isi) in human ventricular myocytes isolated from septal specimens obtained in patients undergoing corrective cardiac surgery were studied using the whole-cell clamp method. A first series of experiments was performed under normal standard superfusion. Clamping from -60 mV evoked an inward current with a threshold at about -35 mV, a maximum around +10 mV and an apparent reversal potential at about +55 mV. No overlapping transient or background outward currents were detected in the -60 to +30 mV potential range, but time-dependent and steady-state outward currents were elicited at potentials above +30 mV. An overlap of steady-state activation and inactivation curves was present between -30 and +10 mV and a slight relief from inactivation was observed for voltages positive to +10 mV. The time course of inactivation consisted of fast and slow phases with time constants differing by a factor of eight. Slow time constants of inactivation were shorter at potentials that elicited larger Isi, and longer at potentials inducing smaller Isi. Recovery from inactivation evolved slowly with 100% reactivation occurring in about 4000 ms. Switching the holding potential from -60 to -40 mV led to a reversible decline of Isi without any change of the decay time constants. Isi was significantly increased by 0.1 microM isoproterenol. Total or partial inhibition by inorganic (2 mM Mn2+, 3 mM Co2+, 1 mM Cd2+) and organic (1 microM methoxyverapamil, 5 microM diltiazem) calcium antagonists did not unmask any transient outward current. However, a consistent increase of Isi was reversibly observed with 3 mM 4-aminopyridine while using standard solutions. A second series of experiments carried out with K(+)- and Na(+)-free solutions did not demonstrate any significant change from data observed with standard solutions except a reduction of outward currents at steps above +30 mV and alteration of inactivation kinetics. In this experimental setting, 4-aminopyridine also increased Isi but to a lesser degree. We conclude that Isi, as compared to the outward currents, is dominant in the diseased human ventricular cells we have studied.

Comparison of the myocardial distributions of 201Tl and 99Tcm-MIBI on SPECT images.

The distributions of 201Tl and 99Tcm-MIBI on stress images were quantitatively measured in a series of 15 patients presenting with documented coronary artery disease. Following two sequential, one-week apart, peak-exercise injections of either 74 MBq of 201Tl or 370 MBq of 99Tcm-MIBI, tomographic views of the myocardium were reconstructed and two thick, central short-axis sections were divided into nine sectors. A sector was considered as showing a defect if its relative activity was lower than 30, 40, 50 or 60% of the highest level of activity in the 18 sectors. Results demonstrate that there were more defects with 201Tl than with 99Tcm-MIBI. However, the difference disappeared if the inferior wall was not included. These results suggest that depth attenuation could be, at least partly, responsible for the higher rate of positive results observed in single photon emission computed tomography with 201Tl than with 99Tcm-MIBI.

[Association of cor triatriatum and obstruction of abnormal left pulmonary venous drainage. Apropos of a case]. / Association d'un coeur triatrial à une obstruction au retour veineux pulmonaire anormal gauche. A propos d'une observation.

A case of subtotal cor triatriatum associated with a partial anomalous pulmonary venous drainage of the left lung, in a 30 months old boy is reported. Diagnosis was suggested by the presence of pulmonary venous obstruction and pulmonary hypertension. Doppler, echocardiogram diagnosed the cor triatriatum and the degree of the pulmonary hypertension. The cine-angiography demonstrated the anomalous, obstructive, left pulmonary venous drainage. The pulmonary hypertension has mandatorised an early surgical cure, the result was satisfactory at 16 months.

[Assisted circulation by external heterotopic prosthesis as a bridge to heart transplantation]. / Assistance circulatoire en attente de transplantation cardiaque par prothèse hétérotopique externe.

Eleven patients aged 7 to 58 years were placed on assisted circulation with Pierce (2 cases) or Abiomed (9 cases) external prosthetic ventricles as a bridge to cardiac transplantation. The indications were terminal cardiac failure following cardiomyopathy (7 cases), decompensated ischemic heart disease (3 cases) and subacute post-transplantation rejection (1 case). The duration of the assisted circulation ranged from 24 hours to 11 days. All patients were transplanted but 3 died after transplantation (27%). The circulatory assistance was satisfactory in all patients as shown by the regression of clinical signs of low cardiac output and the normalisation of diuresis. The complications observed during assisted circulation and after cardiac transplantation were: haemorrhage (36%), infection (27%) and thromboembolism (9%). These preliminary results with a 72% post-transplantation survival rate, show that both systems are effective "bridges to cardiac transplantation". The Abiomen device is excellent value for money and relatively simple to install and represents a good compromise between the sophisticated techniques of circulatory assistance and the problems of the cost of health care.

[Brucella endocarditis caused by reinfection of an aortic Starr valve. Apropos of a case with a favorable development after valvular replacement]. / Endocardite brucellienne par réinfestation sur valve de Starr aortique. A propos d'un cas d'évolution favorable après remplacement valvulaire.

We report the case of a 36-year old male patient who was admitted for subacute endocarditis on an aortic prosthetic valve implanted 14 years previously for endocarditic valve regurgitation; no pathogen had been isolated at that time. Nine blood cultures were positive for Brucella abortus. The conventional antibiotic therapy did not prevent the formation of an abscess below the aortic annulus. A third antibiotic combination (quinolone and rifampicin) resulted in pyrexia prior to surgery. An atrioventricular block initially noted raised the problem of an associated myocarditis. The risk of Brucella infection existed before the first operation, and five serological tests were positive for that organism between the two episodes, which makes reinfection highly probable. This is the third case of Brucella endocarditis on a prosthetic valve. Its originality lies in its mechanism.

[The kidney in Refsum's disease. Clinical, histologic and ultrastructural study of a case]. / Le rein dans la maladie de Refsum. Etude clinique, histologique et ultrastructurale d'une observation.

A renal biopsy was performed in a 41 year old man with Refsum's disease, following the onset of renal failure. 30% of the glomeruli were sclerosed, the others appeared normal. Ultrastructural examination revealed several types of inclusions within the tubular epithelial cells: dense bodies, simple or complex lipidic vacuoles and particularly structures composed of quadrangular microtubules with sides measuring 400 angstrom, rarely encountered in renal pathology. These dense elements, devoid of membrane and often in close contact with lipidic vacuoles, are found within the epithelial cells of the distal convoluted tubules and Henle's loops. They were localized extramitochondrially and no specimen was suggestive of a degraded form of the mitochondria. Some analogy can be made with the renal inclusions observed in Gaucher's disease.

[Acute myocarditis in Lyme's syndrome. Value of myocardial scintigraphy with gallium 67]. / Myocardite aiguë au cours d'un syndrome de Lyme. Intérêt de la scintigraphie myocardique au gallium 67.

The authors report the case of a 35 year old man with no known previous cardiac disease. One month after a tic bite causing diffuse abdominal erythema, he was admitted to hospital with fever, breathlessness and bradycardia. The electrocardiogramme showed first degree atrioventricular block with a sinoatrial block (SA = 200 ms, AH = 240 ms). Echocardiography eliminated the diagnosis of pericardial effusion. Thallium 201 myocardial scintigraphy was pathological and showed irregular global uptake suggesting cardiomyopathy. Gallium 67 scintigraphy showed increased uptake in the left ventricle. The evolution was uncomplicated with normalisation of clinical, ECG and radiological changes. Cardiac catheterisation and angiography eliminated ischaemic and primary cardiomyopathy. Control radionuclide investigations were normal at one month: there was no persistent abnormal Gallium uptake. The diagnosis of Lyme's syndrome was confirmed by positive serology with successive titres of 1/1024 and 1/2048 (significant at titres over 1/256). This unusual case illustrates: the risk of myocardial disease in Lyme's syndrome; the diagnostic value of Gallium 67 scintigraphy in acute myocarditis: Gallium seems to fix specifically on inflamed tissues, so distinguishing myocarditis from primary cardiomyopathies.