Assessment of the physical performance in children with asymptomatic pre-excitation.

AIMS: Pre-excitation syndrome can lead to recurrent supraventricular tachycardias (SVTs) and carries a risk of sudden cardiac death (SCD). However, an underestimated consequence of antegrade conduction through an accessory pathway is fusion of intrinsic and accessory conduction that causes asynchronous activation and myocardial contraction that could be a cause for cardiac dysfunction and dilation. It is not known to what extent pre-excitation affects myocardial and physical performance in those patients. The aim of the study was to assess to what degree ventricular pre-excitation affects physical performance in children, using cardio-pulmonary exercise testing (CPET). METHODS AND RESULTS: The study group consisted of 30 asymptomatic children, aged 8-17 years, with pre-excitation and no history or documentation of SVT compared to 31 healthy controls matched according to sex and age. All patients underwent routine cardiology assessment and then CPET. Echocardiography showed there were no differences in the left ventricular size and function between the study and control group. During the CPET both, patients and controls achieved maximal effort. Patients in the study group showed significantly lower values of VO2max and anaerobic threshold when compared to controls. The most affected subgroup was patients with persistent pre-excitation throughout the exercise. CONCLUSIONS: Physical performance is affected in children with pre-excitation. This effect is stronger in patients with persistent delta wave observed throughout the exercise.

Right ventricular function assessment using tissue Doppler imaging and speckle tracking echocardiography.

Modern echocardiographic techniques, i.e. tissue Doppler imaging and speckle tracking echocardiography, allow for an assessment of global and regional right ventricular function. The right ventricular myocardial performance index and tricuspid annulus motion are used in the assessment of global right ventricular function, whereas duration of the cardiac cycle phases and myocardial velocities are used in the assessment of regional function. Strain and strain rate allow for an evaluation of both regional and global myocardial function. Literature reports provide data on the usefulness of these methods in patients with pressure and volume overload as well as with direct myocardial damage involving the right ventricle. In pulmonary hypertension, S' wave assessment may be used for therapeutic efficacy evaluation. Longitudinal strain reduction indicates an increased risk of vascular events, while an increased value of myocardial performance index is a predictor for a survival in pulmonary hypertension. A decreased S' wave velocity is associated with limited pulmonary vascular flow in patients with pulmonary embolism. In patients after atrial baffle repair for transposition of the great arteries, decreased longitudinal strain was an independent predictor for heart failure. A statistically significant decrease in both the S' wave as well as acceleration during isovolumic contraction were observed in arrhythmogenic right ventricular cardiomyopathy. S' wave and global right ventricular longitudinal strain values were lower in patients in the acute phase of myocardial infarction involving the right ventricle compared to the corresponding parameters in healthy individuals. In the case of tetralogy of Fallot correction, the evaluation of S' wave velocity may prove useful in identifying patients with reduced cardiac systolic reserve; a good correlation was also found between the global right ventricular longitudinal strain and right ventricular ejection fraction in MRI.

Usefulness of NT-proBNP in assessment of right ventricular function in children after tetralogy of Fallot correction - a preliminary study.

BACKGROUND: Although surgical treatment for tetralogy of Fallot (TOF) has been used with considerable success, right ventricular function may remain altered after repair. The NT-proBNP assessment has been shown to be a reliable parameter for the heart failure assessment. AIM: To determine NT-proBNP values in assessment of right ventricular function in children after TOF correction. METHODS: In 20 patients after TOF correction aged from 10 to 17 years (follow-up period ranged from 7 to 16 years) NT-proBNP level at rest and after exertion, treadmill test and echocardiography were performed. In the control healthy children NT-proBNP level at rest was assessed. RESULTS: The mean values of NT-proBNP level in the TOF patients were significantly higher than in controls (11.0 +/- 12.0 fmol/l and 5.4 +/- 7.5 fmol/l, p < 0.05). In patients repaired with a transannular patch the mean value of NT-proBNP level was higher than in children operated on without a transannular patch (18.3 +/- 16.5 vs. 6.8 +/- 7.9 fmol/l, p < 0.05). In children in whom physiological shortening of QRS complex during treadmill test was observed, NT-proBNP level was lower (mean values at rest 5.0 +/- 4.8 fmol/l and after exertion 7.3 +/- 6.3 fmol/l) compared to patients with prolongation of QRS duration (mean values at rest 17.7 +/- 15.6 fmol/l and after exertion 20.3 +/- 17.8 fmol/l) (p < 0.05). Significant differences in NT-proBNP levels between children with severe pulmonary regurgitation and mild/moderate pulmonary regurgitation were detected (mean values at rest 18.6 +/- 15.0 vs. 4.2 +/- 3.9 fmol/l and after exertion 20.0 +/- 18.6 vs. 5.7 +/- 4.6 fmol/l) (p < 0.05). The NT-proBNP levels were also higher in children with severe tricuspid valve insufficiency compared to children with mild/moderate tricuspid valve regurgitation (mean values at rest 19.5 +/- 15.0 vs. 4.9 +/- 3.7 fmol/l and after exertion 22.5 +/- 17.1 vs. 7.0 +/- 4.6 fmol/l). CONCLUSIONS: The NT-proBNP level in patients after TOF correction is higher than in healthy children. The NT-proBNP level is higher and exertion tolerance is lower in children repaired with rather than without transannular patch. In patients with severe pulmonary regurgitation and/or severe tricuspid valve insufficiency NT-proBNP level is higher than in patients without right ventricular volume overload. The measurement of NT-proBNP level might be helpful in order to separate those patients after TOF correction who are at increased risk of heart failure and arrhythmia.