Final answer:
In constrictive pericarditis, cardiac catheterization shows a dip-and-plateau waveform, also known as the 'square root sign', due to the constricted, non-compliant pericardium halting rapid ventricular filling.
Step-by-step explanation:
Cardiac catheterization findings in constrictive pericarditis typically include a dip-and-plateau waveform. This waveform is characterized by a deep y descent followed by a rapid rise and plateau during ventricular filling on the ventricular pressure curve. The sharp y descent occurs due to the rapid early filling of the ventricles, which is suddenly halted by the non-compliant, constricted pericardium, thereby creating the plateau phase. This pattern is sometimes referred to as 'square root sign' due to its resemblance to the mathematical symbol. It contrasts with other abnormalities such as an increased 'a' wave that may indicate atrial hypertension or conditions affecting the atria, increased 'v' wave that can be seen in conditions like tricuspid regurgitation, or an increased peak-to-peak pressure gradient which would not typically be a feature of constrictive pericarditis.