A new device and method are introduced herein to facilitate vascular access in general and the placement of central venous access devices in particular. In one embodiment, the device consists of the following components: a wireless ultrasound imaging handheld scanner, a Bluetooth ECG (electrocardiography) data acquisition module with patient ECG cable and sterile adaptor, and a mobile medical application running on a mobile platform (device), e.g., a tablet, smartphone or smart watch. Ultrasound imaging and/or ECG-based catheter guidance provided by the device disclosed herein can be used to independently or simultaneously visualize the catheter in the vasculature and/or guide its placement at the desired location. In another embodiment of the present invention, ultrasound imaging of the blood vessel targeted for vascular access can be used for assessing the blood vessel size prior to cannulating the blood vessel, for guiding an access needle into the targeted blood vessel, and for visualizing the catheter in the vasculature after the introduction of the catheter. In another embodiment of the present invention, ECG-based navigation of an intravascular catheter can be used for tracking such intravascular catheter in the vasculature and positioning such intravascular catheter at a desired location. In one aspect of the present invention, the ultrasound imaging handheld scanner contains all the electronics required to acquire and process ultrasound images and to transfer them wirelessly to a mobile platform device, e.g., a tablet or a smartphone. In another aspect of the present invention, the ECG data acquisition module contains all the electronics required to acquire and process tracking and positioning information for ECG-based catheter guidance and to transfer such information wirelessly to a mobile platform device, e.g., a tablet or a smartphone. In another aspect of the present invention, algorithms are introduced for processing and synchronization of ultrasound