Ultrasound in paediatric cardiology — state of the art

The development of ultrasound technology to visualize cardiac structures, based on the pioneering work by Edler and Hertz at the University of Lund in Sweden, has literally created a revolution in the field of paediatric cardiology. Before the era of cardiac catheterization and echocardiography the diagnosis of congenital heart disease was mainly based on combining physical findings, cardiac auscultation, electrocardiogram (ECG), and chest X-ray. This was largely based on the work by Helen B. Taussig at John Hopkins in the 1930s who established the field of clinical paediatric cardiology by integrating pathology knowledge with clinical findings. Diagnosis at that time was based on clinical skills and was more an art than science. The introduction of paediatric cardiac surgery in the 1950s was made possible due to the simultaneous development of cardiac catheterization and angiography which allowed an accurate description of the different cardiac lesions and the associated haemodynamics prior to surgery. For a long period catheterization was the diagnostic gold standard and all surgical patients underwent an invasive cardiac evaluation. In the 1970s, echocardiography was developed as a clinical tool and due to its non-invasive nature, was introduced quickly in paediatric cardiology. As anatomical diagnosis is challenging by M-mode echocardiography, it was really the development of two-dimensional (2-D) echocardiography in the late 1970s and early 1980s that deeply influenced the field. For the first time the congenital defects could be imaged noninvasively and the 2-D images were extensively validated by comparing them with pathological and surgical findings. Adding pulsed, continuous, and colour Doppler data to the 2-D images resulted in a complete detailed description of congenital cardiac defects and their haemodynamic consequences. Further optimization of ultrasound technology specifically for paediatric imaging, such as the development of higher-frequency probes and increasing the standard grey-scale frame rates, further improved spatial and temporal resolution and overall image quality. Based on its excellent diagnostic accuracy and its non-invasive nature, echocardiography quickly became the primary non-invasive diagnostic technique for all children with heart disease. Currently every paediatric patient with suspected heart disease will undergo an echocardiographic examination as the first (and often only) diagnostic test.