Congenital heart defects affect 1 in 100 births in France, with rising prevalence due to better care. Despite improved survival, 40% of children post-surgery face neurological impairments, and some of them show brain lesions. Causes include heart defects, genetic syndromes, and surgeries. Some heart defects and support systems increase cerebral risks. Monitoring cerebral perfusion is difficult to assess but emerging ultrafast ultrasound offers real-time, non-invasive blood flow insights.

Congenital heart defects affect 1 in 100 live births in France. While incidence remains stable, prevalence is rising due to improved medical care, with cases expected to double by 2050. Despite increased survival, neurological comorbidities remain a major concern, with 40% of patients undergoing childhood cardiac surgery experiencing impairments and 73% presenting MRI-detectable brain lesions postoperatively. These injuries result from congenital heart defects, haemodynamic disturbances, genetic syndromes, and neonatal surgeries with extracorporeal circulation.

Some heart defects, such as systemic-to-pulmonary shunts and cyanotic heart diseases, impair cerebral perfusion, increasing the risk of hypoxia and stroke. Mechanical circulatory support systems (e.g. ECMO, cardiopulmonary bypass) also contribute to cerebral risks due to hypoperfusion and clotting complications.

Cerebral autoregulation helps maintain stable perfusion despite blood pressure variations. However, bedside cerebral perfusion monitoring remains challenging leading to reliance on indirect methods like near-infrared spectroscopy (NIRS) and transcranial Doppler (TCD), both with limitations. Ultrafast ultrasound (UFUS) is an emerging non-invasive technique that enables real-time quantification of cerebral blood flow, offering new insights into neonatal cerebral haemodynamics.

Inclusion Criteria:

• Every patient under 2 years old any sex or gender hospitalised in the congenital heart disease unit of the intensive care and anaesthesia for cardiovascular surgery, CHU de Bordeaux.
• Open anterior fontanella
• congenital heart disease
• cardiac shock necessitating mechanical circulatory support.
• Social security affiliation
• Parental or legal guardian's non-opposition

Exclusion Criteria:

• Anechoic
• Allergy to echocardiography gel.

Every patient, under two years old, receiving a transcranial Doppler in routine care in our CHD unit of intensive care and anaesthesiology for cardiovascular surgery department.