Cardiac catheterization was the primary tool in the diagnosis and evaluation of congenital heart disease. Before the emergence of echocardiograms, clinical suspicion of congenital heart disease required a cardiac catheterization for definitive diagnosis, possible intervention, and pre-surgical planning.

Cardiac catheterization can provide information such as angiographic images by fluoroscopic imaging during contrast injection, pressure measurements, oxygen blood saturations, and estimations of cardiac output and pulmonary vascular resistance.

Pressure measurements are taken by way of a fluid-filled pressure transducer attached to a catheter with end-holes that are passed through various vessels and structures in the heart.

The transducer produces cardiac pressure waveforms that are interpreted by the interventionalist .

This is especially important in the evaluation of stenosis, diastolic dysfunction, and pulmonary vascular resistance.