The catheterisation laboratory (cath lab) continues to advance with updated technology and novel devices, allowing catheter-based interventions on more complex cases of congenital and acquired heart disease with the added benefit of reduced radiation exposure. Today, a wider range of catheter-based interventions exist, replacing or postponing the need for a surgical approach. Even extremely preterm infants (some less than 800 g) can now be offered interventional procedures in the cardiac catheter laboratory. Conversely, there is a reduced need for cardiac catheterisation as a purely diagnostic tool, as non-invasive imaging modalities such as cardiac CT and MRI continue to increase in their application and sophistication. The anaesthetist will find themselves undertaking high-risk anaesthetics, with challenges inherent to the cath lab, with riskier and more complex children, in a location which may be remote from the theatre suite. Anaesthetists managing children with complex congenital cardiac disease have to understand the pathophysiology of these patients and, importantly, the effects that anaesthesia and any intervention will have on their underlying physiology.