Birol Çotuk

Athlete's heart in prepubertal male swimmers.

To determine the cardiac response to intensive endurance training during prepuberty, we studied 22 male prebubertal swimmers who had been trained for at least 3 years, with a mean of 3.91 years and a standard deviation of 1.10 years, and 8 hours per week, the mean being 10.0 hours and the standard deviation 1.7 hours. The control group consisted of 21 boys of similar age, height and weight (p is more than 0.05 for all), who were not participating regularly in sporting activities. Left ventricular dimensions and systolic function were examined with M-Mode; velocities and durations of transmitral flow were measured with pulsed wave Doppler; and tissue Doppler velocities and durations were measured with pulsed wave tissue Doppler echocardiography. We determined the regional velocities of the lateral mitral annulus in four-chamber position, the left ventricular posterolateral wall, and the midseptum in long-axis position. Interventricular septal thickness, left ventricular posterior wall thickness, left ventricular mass and relative wall thickness were increased in swimmers (p is less than 0.05). All the tissue Doppler measurements were similar in both groups, except the septal isovolumic relaxation time. We observed that the left ventricular wall thickness had increased concentrically in prepubertal swimmers compared to controls, without a significant change in the left ventricular diastolic diameter. This finding is contrary to the previous studies on adult swimmers. Whether the structural changes observed in our study reflect the unique cardiac adaptation of the hearts of children to exercise will only be disclosed by longitudinal studies of prepubertal athletes.

Coordination dynamics of circulatory and respiratory rhythms during psychomotor drive reduction

A 0.15-Hz rhythm band in cutaneous blood oscillations in awake human subjects was studied in cardiovascular-respiratory time series of five subjects relaxing naïvely or practicing hypnoid relaxation (autogenic training, or AT). Time series analysis used nonlinear algorithms, time-frequency distribution (TFD), postevent scan (PES) method, and linear fast Fourier transform (FFT) algorithm. This 0.15-Hz rhythm band caused phase synchronization with respiration at 1:2, 1:1, and 2:1 integer number (n/m) ratios for extended periods. During wave epochs, the 0.15-Hz rhythm band was amplified, causing the 0.15-Hz rhythm band to also appear in interbeat intervals and arterial blood pressure fluctuations. If phase synchronization of the 0.15-Hz rhythm band with respiration was established at a 1:1 integer number ratio, it was maintained and resulted in consensualization of all cardiovascular-respiratory oscillations at this frequency. Simultaneous cardiovascular and respiratory oscillations at about 0.1 Hz did not affect the appearance of the 0.15-Hz rhythm band in the photoplethysmography (PPG) signal. Recent evidence suggests the emergence of the 0.15-Hz rhythm band and n/m phase synchronization to result from nonequilibrium phase transitions operational in the network of lower brainstem neurons and associated parasympathetic neuronal effectors. These findings corroborate our notion of the 0.15-Hz rhythm band as a marker of the trophotropic mode of operation.

Sporcu çocuklarda QT dispersiyonu Orijinal Araştırma

Aim: The risk of sudden death due to ventricular hypertrophy in athletes is controversial The relation of increased QT dispersion QTd with non homogeneous ventricular repolarization and arrhythmia in patients with hypertrophic cardiomyopathy is previously demonstrated We investigated if sports related ventricular hypertrophy causes such an abnormality in ventricular repolarization Material and Method: Twenty eight swimmers and 20 healthy children between 9 and 12 5 years of age were evaluated by history physical examination 12 lead electrocardiography and echocardiography Heart rate QT interval corrected QT QTc QTd and QTc dispersion QTcd values were compared Results: Echocardiographic measurements of swimmers were within the normal limits according to their weight However the interventricular nbsp; septal nbsp; thickness IVSd nbsp; left ventricular nbsp; posterior nbsp; wall nbsp; thickness LVPWd nbsp; left ventricular end diastolic diameter LVDd left ventricular mass were significantly increased in swimmers compared to the control group p lt;0 0001 0 009 0 046 lt;0 0001 respectively There was no statistical difference in terms of heart rate QT interval QTc QTd QTcd Conclusions: Absence of increased QT dispersion in athletes indicates that the ventricular repolarization is not heterogeneous and the arrhythmia risk is not higher than the normal population in this group Turk Arch Ped 2007; 42: 117 20 Key words: QT dispersion athletes heart sudden death arrhythmia