Echocardiography in congenital heart disease: usefulness, limits and new techniques.

Echocardiography represents the non-invasive tool most commonly used in pediatric cardiology. Indeed, it enables the definition of both the morphological and functional findings in congenital heart disease (CHD), as completely as possible in almost all the cases. In comparison with adult subjects, the echocardiographic evaluation in pediatric patients requires a different approach, providing information on the heart position in the thorax, the atrial situs viscerum, the vein-atrial and the atrio-ventricular connections, the relationship between the ventricles, the ventriculo-arterial connection and the relationship of the great arteries (segmental analysis). In addition, the echocardiographic study should include a non-invasive study of ventricular function, as mandatory to warrant an optimal pre- and postoperative management in patients with CHD. The indices most commonly utilized to assess ventricular mechanics are the 'pump indices' (i.e. ejection fraction or fractional shortening). Unfortunately, they may lead to invalid data, because of their dependence on loading conditions and heart rate. As a consequence, echocardiographic indices should be used (i.e. fiber shortening or rate-corrected velocity of circumferential fiber shortening-end systolic stress relationship), which better reflect the intrinsic myocardial contractility. More recently, evidence is mounting that new echocardiographic techniques (i.e. Doppler myocardial imaging, strain/strain rate and backscatter) may offer new insights in terms of regional functional and textural findings of the myocardium. However, long-term follow-up studies will be necessary to better define their real impact in the clinical setting.