Cardiac catheterisation is crucial for diagnosing and treating paediatric heart diseases, but it is poorly tolerated by small children, infants, and newborns without sedation. This study investigated whether maternal voice during sedation could lower stress and pain in children undergoing cardiac catheterisation and also assessed mothers’ stress levels before and after the procedure.

This was a prospective, monocentric, randomised, controlled interventional study at the University Hospital Bonn. Children aged 4 years or younger scheduled for elective cardiac catheterisation under procedural sedation and American Society of Anaesthesiologists class between 1 and 3 were eligible.

At the end of cardiac catheterisation, the intervention group showed a higher Newborn Infant Parasympathetic Evaluation index with an adjusted mean difference of 9.5 (± 4.2) (p = 0.026) and a lower median Children’s and Infants Postoperative Pain Scale score of 2.0 (IQR: 0.0–5.0) versus 4.5 (IQR: 3.0–6.0) than the control group (p = 0.027). No difference in the children’s cortisol level was found (p = 0.424). The mothers in the intervention group had a lower cortisol level than those in the control group before cardiac catheterisation (adjusted mean difference: −4.5 nmol/l (± 1.8 nmol/l), p = 0.011).

Listening to the maternal voice during cardiac catheterisation could lead to less postoperative pain and significantly lower stress and discomfort level in children. Less pain could reduce the incidence of postoperative delirium.

Additionally, mothers perceived involvement as positive. A reduced stress level of mothers can positively influence children and possibly reduce pain and anxiety.