30 patients with severe aortic valve stenosis presented in severe congestive heart failure within the first 2 months of life. In 25 of them, left ventricular volume and contractility were assessed; five of them had a left ventricle of normal size, in 11 left ventricular size was diminished, and in nine patients it was enlarged. Eleven of the infants had extensive endocardial fibroelastosis (EFE) evidenced angiographically by myocardial sinusoids in ten of them and established at autopsy in six. The presence of EFE correlated with the size of the left ventricle; eight of 11 with a small left ventricle, two of five with a normal-sized left ventricle, and one of nine with an enlarged left ventricle displayed EFE. The severe depression of left ventricular function associated with EFE was documented by left ventricular volume determinations on exclusion of the myocardial sinusoids. Of 30 patients, 12 (including eight of 26 who underwent surgery) did not survive. Mortality, severity, and early onset of symptoms were associated mainly with small size of the left ventricle and with the severe left ventricular dysfunction associated with EFE.

To elucidate further the special nature of anaerobic threshold in children, 11 boys, mean age 12.1 years (range 11.4-12.5 years), were investigated during treadmill running. Oxygen uptake, including maximal oxygen uptake (VO2max), ventilation and the "ventilatory anaerobic threshold" were determined during incremental exercise, with determination of maximal blood lactate following exercise. Within 2 weeks following this test four runs of 16-min duration were performed at a constant speed, starting with a speed corresponding to about 75% of VO2max and increasing it during the next run by 0.5 or 1.0 km.h-1 according to the blood lactate concentrations in the previous run, in order to determine maximal steady-state blood lactate concentration. Blood lactate was determined at the end of every 4-min period. "Anaerobic threshold" was calculated from the increase in concentration of blood lactate obtained at the end of the runs at constant speed. The mean maximal steady-state blood lactate concentration was 5.0 mmol.l-1 corresponding to 88% of the aerobic power, whereas the mean value of the conventional "anaerobic threshold" was only 2.6 mmol.l-1, which corresponded to 78% of the VO2max. The correlations between the parameters of "anaerobic threshold", "ventilatory anaerobic threshold" and maximal steady-state blood lactate were only poor. Our results demonstrated that, in the children tested, the point at which a steeper increase in lactate concentrations during progressive work occurred did not correspond to the true anaerobic threshold, i.e. the exercise intensity above which a continuous increase in lactate concentration occurs at a constant exercise intensity.

No abstract

Immediate and medium-term experience with transcatheter closure of a secundum atrial septal defect by the "buttoned" device in seven patients is reported. Complications occurred in two patients during the procedure. In one patient with complications, the occluder was partly released in the right atrium. All efforts to correct its position were unsuccessful and caused considerable deformation of the device, which had to be removed surgically. In the other patient with complications, disconnection of the occluder and counteroccluder occurred immediately after removal of the loading wire. Both parts were retrieved by catheter. Five patients had uneventful closure of the atrial septal defect. On follow-up, however, displacement of the device towards the mitral valve was observed in two patients, which caused mitral regurgitation. Surgical removal of the device and repair of the mitral valve was necessary in both patients. Two years after the procedure, the atrial septal defect was closed completely in two of the remaining three patients and a small residual defect persisted in one patient.

To evaluate whether anaerobic threshold criteria evaluated in adults are pertinent to children, ten boys with a mean age of 11.2 years were investigated during treadmill running. Maximal running velocity was determined at stepwise increasing load, with determination of blood lactate following exercise. On the following days four runs each lasting 16 min were performed at a constant speed starting with a speed corresponding to about 70% of the maximal speed and increasing it during the next run in order to determine maximal steady state levels of blood lactate. Blood lactate was measured at the end of every 4 min period. From this date the anaerobic threshold was calculated. The correlation between anaerobic threshold values and maximal steady state levels of blood lactate was poor, however, a steady state of blood lactate was present at 4.6 mmol/l, whereas the mean anaerobic threshold value was determined at 2.6 mmol/l. In view of our results, the anaerobic threshold during increasing work does not correspond to the true anaerobic threshold, which can be assumed to occur at much higher lactate values. The meaning of the term anaerobic threshold is therefore to be questioned.

No abstract

A complete atrioventricular block was seen in a nine year old girl in whom an infection with Borrelia burgdorferi was confirmed by serological testing. There were no other symptoms or cutaneous manifestations of the disease. Though a rash on the right ear was later recalled by her parents. The patient was treated with high dose penicillin and orciprenaline was given intermittently. The complete heart block disappeared within four days.

Balloon valvuloplasty (BVP) of pulmonary stenosis (PST) was performed in 305 infants and children in 20 heart centres of the Federal Republic of Germany. 273 patients suffered from isolated PST. Their age ranged from 3 days to 18 years (mean = 5.85 +/- 4.82 years), their weight from 2.9 to 60 kg. The pressure gradient was measured invasively in the sedated or anaesthetized child, partly by CW Doppler. BVP was performed by mono- or trefoil catheters, mostly oversized. As a result, mean pressure gradient fell from 71.7 +/- 32 mmHg before to 31.8 +/- 25 mmHg immediately after BVP (P less than 0.0001). The gradient was reduced by less than 30% in 13% of the patients, by 30-49% in 23%, and by greater than or equal to 50% in 64%. Among 33 patients with a gradient reduction of less than 30%, nine were aged less than 1 year, nine had dysplastic valves, and nine had a short-term infundibular reaction and good late results. Gradient reduction was not improved with oversized balloons and was independent of the initial gradient. Follow-up for a mean 11.2 +/- 8 months showed a further slight improvement, probably due to regression of infundibular hypertrophy. In the whole group we observed infundibular reaction in 12%, serious complications with one late death in 4%. From the start, BVP proved to be a secure and effective tool for elimination of pulmonary stenosis.