Medical apparatus for the introduction of catheters into the human body, comprising: an ECG device having at least three electrodes, positionable on a human body for the detection of surface electrical potential data and adapted to provide at output at least one surface ECG strip; at least one catheter element having a distal ending part positionable inside said human body and having an auxiliary electrode element for the detection of intracavitary electrical potential data, associated with said ECG device for sending to the latter said intracavitary data, said ECG device being adapted to provide at output at least one intracavitary ECG strip; an electronic device associated with said ECG device for the receipt of at least said intracavitary ECG strip and comprising a data processing module adapted to process at least said intracavitary ECG strip to obtain usage information adapted at least to provide instructions on the insertion of said catheter element in said human body, characterized in that that said module comprises first data processing means associated with said ECG device for the acquisition of at least said intracavitary ECG strip to obtain recognition data (Q, R, S, P, T, V, W, J) adapted to provide analytical information on said intracavitary ECG strip, said first processing means comprising a first data processing unit receiving at input at least said intracavitary ECG strip to obtain first recognition data (Q, R, S, P, T, V, W) of maximum and minimum points of the same strip, and in that said usage information is at least in part of the type of heights measurable between the absolute maximum point and the minimum absolute point of an intracavitary ECG strip for a given cardiac cycle. an ECG device having at least three electrodes, positionable on a human body for the detection of surface electrical potential data and adapted to provide at output at least one surface ECG strip; at least one catheter element having a distal ending part positionable inside said human body and having an auxiliary electrode element for the detection of intracavitary electrical potential data, associated with said ECG device for sending to the latter said intracavitary data, said ECG device being adapted to provide at output at least one intracavitary ECG strip; an electronic device associated with said ECG device for the receipt of at least said intracavitary ECG strip and comprising a data processing module adapted to process at least said intracavitary ECG strip to obtain usage information adapted at least to provide instructions on the insertion of said catheter element in said human body, characterized in that that said module comprises first data processing means associated with said ECG device for the acquisition of at least said intracavitary ECG strip to obtain recognition data (Q, R, S, P, T, V, W, J) adapted to provide analytical information on said intracavitary ECG strip, said first processing means comprising a first data processing unit receiving at input at least said intracavitary ECG strip to obtain first recognition data (Q, R, S, P, T, V, W) of maximum and minimum points of the same strip, and in that said usage information is at least in part of the type of heights measurable between the absolute maximum point and the minimum absolute point of an intracavitary ECG strip for a given cardiac cycle.