The goal of this observational study is to demonstrate the presence of a correlation between echographic measurements of the inferior vena cava (IVC) normalized for the pediatric population and right atrial pressures (RAP) measured by central venous catheter (CVC) so as to create a predictive model of the value of right atrial pressures using echocardiographic parameters in the pediatric population. This study is single-center longitudinal and involves retrospective and prospective data collection.

Primary objective:

- To build a mathematical predictive model of RAP specifically for paediatric patients from echocardiographic parameters analysed on a retrospective cohort.

Secondary objectives:

• To evaluate the accuracy on the paediatric patient of the mathematical model in use for the estimation of RAP in adult patients in a prospective cohort.
• To test the mathematical model built in this study in a prospective cohort of patients OUTCOME With regard to the primary objective, a new patient-specific model will be built paediatric patient from different methods of ultrasound measurement of the IVC (maximum and minimum diameter expressed as z-score, ratio between the two diameters, ratio between maximum diameter and systolic diameter of the aorta).

systolic diameter of the aorta), as well as the patient's auxo-anthropometric values collected by means of the retrospective data.

With regard to secondary objectives, the mathematical model in use for the patient will be applied adult patient to estimate the RAP in our patients and the value obtained will be compared with the value measured.

Inclusion Criteria:

• Pediatric patients aged 0-18 years undergoing central venous catheter (CVC) placement in the course of the diagnosis performed at our center
• Obtaining informed consent from parent/guardian in case of minors

Exclusion Criteria:

- Patients with univentricular cardiac physiology, nonsinus heart rhythm, mechanical ventilation, Inferior vena cava thrombosis and patients with isomerism

The retrospective population consists of all patients admitted at the Pediatric Cardiology Unit of IRCCS AOU of Bologna and underwent central venous catheter placement (CVC) during the normal diagnostic-therapeutic course from 1st January of 2012 for which a complete echocardiography was performed within 1 hour of RAP (right atrial pressure) measurement. The prospective population consists of all patients admitted at the Pediatric Cardiology Unit of the IRCCS AOU of Bologna from the time of approval by the ethics committee and undergoing central venous catheter placement for 12 months after the start of this study.