Apparatus and methods relating to intravascular positioning of distal end of catheter

1. A system for positioning a medical device in a patient, comprising:

a stylet including:

a magnetic assembly configured to produce a magnetic field, the magnetic assembly positioned along a distal portion of the stylet; and

a stylet electrode positioned distal of the magnetic assembly, the stylet electrode designed to function as both an interior excitation electrode and an interior detection electrode;

a stylet advancement assembly configured to advance a distal end of the stylet from a first position in the medical device to a second position distal of the medical device; and

an external assembly including:

an external sensor configured for sensing the magnetic field to determine a position of the magnetic assembly relative to the external sensor;

a first external electrode configured for placement on the patient; and

a second external electrode configured for placement on the patient,

wherein the stylet electrode, the first external electrode, and the second external electrode generate an electric field producing field measurements, and

wherein a conductance curve is generated from the field measurements, the conductance curve configured to provide positional information of the stylet electrode with respect to an obstruction or malposition.

2. The system for positioning according to claim 1 , wherein the first external electrode is an excitation electrode, and the second external electrode is a detection electrode.

3. The system for positioning according to claim 1 , further comprising a display, wherein the conductance curve and the magnetic assembly are configured for simultaneous depiction on the display.

4. The system for positioning according to claim 3 , wherein the medical device is a blood vessel catheter, and wherein the external sensor is placed on a chest of the patient during positioning of the blood vessel catheter.

5. The system for positioning according to claim 1 , wherein the magnetic assembly includes a plurality of permanent magnets positioned consecutively along the distal portion of the stylet.

6. The system for positioning according to claim 1 , wherein the stylet electrode is designed to detect ECG signals of the patient.

7. The system for positioning according to claim 1 , further comprising an exterior ultrasound probe configured for ultrasonically imagining a vessel of the patient.

8. The system for positioning according to claim 7 , further comprising a display configured to generate a graphical representation of a relative cross-sectional area of the vessel along a path utilizing the field measurements.

9. The system for positioning according to claim 1 , wherein the stylet advancement assembly includes a housing including a connector designed to connect to a proximal end of the medical device.

10. The system for positioning according to claim 9 , wherein the stylet advancement assembly further includes a slider disposed in the housing, the slider coupled to the stylet via a stylet retainer, the slider designed to translate from a retracted position to an extended position within the housing.

11. The system for positioning according to claim 10 , wherein the distal end of the stylet is in the medical device in the retracted position, and wherein the distal end of the stylet is distal of a distal tip of the medical device in the extended position.

12. The system for positioning according to claim 10 , wherein the stylet retainer comprises a pierceable septum.