A portable mains electricity (AC-powered) component of an electrocardiographic central venous catheter navigation system intended to process and display electrocardiographic (ECG) data to assist guidance and positioning of a central venous catheter [e.g., peripherally-inserted central catheter (PICC)]. It is a control unit with a monitor (e.g., a dedicated touchscreen unit) intended to be connected to the appropriate ECG cables/leads/catheter (not included). The technique involves the catheter functioning as an intravascular ECG electrode (using the guidewire or intraluminal saline as a conductor) which, along with skin surface ECG data, provides feedback on catheter tip location.