Apparatus and method for catheter navigation using endovascular energy mapping
Devices and methods obtain and use endovascular electrograms (or electrocardiograms/ECGs) in a number of clinical applications and settings. In one embodiment, a method for locating an indwelling medical device within a vasculature of a patient includes identifying an endovascular ECG waveform complex from an endovascular ECG signal associated with the indwelling medical device, then calculating an absolute value of the energy of the endovascular ECG waveform complex over a predetermined segment thereof. A position of the medical device within the vasculature is then determined by observation of the absolute value of the energy of the predetermined segment of the endovascular ECG waveform complex.
1. A method for locating an indwelling medical device within a vasculature of a patient, comprising:
identifying with indicators of a graphical user interface on a display screen of a portable device an endovascular ECG waveform complex from an endovascular ECG signal associated with endovascular electrodes of the indwelling medical device;
determining an energy of the endovascular ECG waveform complex;
calculating an absolute value of the energy of the endovascular ECG waveform complex over a predetermined segment thereof by applying data-processing algorithms of a computer module of the portable device; and
determining a position of the indwelling medical device within the vasculature by observation of the absolute value of the energy of the predetermined segment of the endovascular ECG waveform complex in the graphical user interface by a user of the portable device.
2. The method for locating according to claim 1 , wherein the method is at least partially performed with an ECG signal monitoring system including the display screen for depicting the endovascular ECG waveform complex, and wherein determining the position includes observing information relating to the absolute value of the energy of the endovascular ECG waveform complex as depicted on the display.
3. The method for locating according to claim 1 , wherein the endovascular ECG waveform complex includes both positive energy values and negative energy values, and wherein identifying the endovascular ECG waveform complex includes identifying two successive peaks of an R-wave with the indicators of the graphical user interface.
4. The method for locating according to claim 1 , wherein the endovascular ECG signal is detected by the endovascular electrodes, which are disposed proximate to a distal tip of the indwelling medical device.
5. The method for locating according to claim 4 , wherein the indwelling medical device is a catheter.
6. The method for locating according to claim 1 , wherein the predetermined segment of the endovascular ECG waveform complex includes an entirety of the endovascular ECG waveform complex corresponding to a complete single heartbeat of the patient.
7. The method for locating according to claim 1 , wherein calculating the absolute value of the energy further comprises:
discretely sampling a number of portions of the endovascular ECG waveform complex;
calculating with the data-processing algorithms squares of amplitudes of the endovascular ECG waveform complex at each of the number of discretely sampled portions of the endovascular ECG waveform complex over the predetermined segment;
summing with the data-processing algorithms the squares of the amplitudes; and
dividing with the data-processing algorithms the summed squares of the amplitudes by the number of discretely sampled portions of the endovascular ECG waveform complex.
8. The method for locating according to claim 1 , wherein identifying the endovascular ECG waveform complex further comprises identifying with the indicators of the graphical user interface an R-peak, a P-wave segment, and a P-peak of the endovascular ECG waveform complex on the display screen.
9. The method for locating according to claim 1 , wherein the method is iteratively executed for successively detected endovascular ECG waveform complexes as the indwelling medical device is advanced within the vasculature.
10. The method for locating according to claim 1 , further comprising:
identifying with the indicators of the graphical user interface a skin ECG waveform complex from a skin ECG signal sensed by an electrode on the patient; and
determining an energy of the skin ECG waveform complex;
calculating an absolute value of the energy of the skin ECG waveform complex over a predetermined segment time synchronized with the predetermined segment of the endovascular ECG waveform complex by applying the data-processing algorithms,
wherein determining the position of the indwelling medical device includes determining by the user from the graphical user interface the position of the indwelling medical device based on a ratio of the absolute value of the energy of the predetermined segment of the endovascular ECG waveform complex to the absolute value of the energy of the predetermined segment of the skin ECG waveform complex.
11. A method for locating an indwelling catheter within a vasculature of a patient, comprising:
identifying with indicators of a graphical user interface on a display screen of a portable device an endovascular ECG waveform complex from an endovascular ECG signal associated with endovascular electrodes of the indwelling catheter and a skin ECG waveform complex from a skin ECG signal;
determining an energy of the endovascular ECG waveform complex and an energy of the skin ECG waveform complex;
calculating an absolute value of the energy of the endovascular ECG waveform complex over a predetermined segment thereof and an absolute value of the energy of the skin ECG waveform complex over a predetermined segment thereof by applying data-processing algorithms of a computer module of the portable device, the predetermined segments corresponding in time with one another; and
determining a position of the indwelling catheter within the vasculature from the graphical user interface by a user of the portable device using at least one of the absolute values of the energy of the predetermined segment of the endovascular ECG waveform complex or the energy of the predetermined segment of the skin ECG waveform complex.
12. The method for locating according to claim 11 , wherein determining the position further comprises determining the position of the indwelling catheter based on a ratio of the absolute value of the energy of the predetermined segment of the endovascular ECG waveform complex to the absolute value of the energy of the predetermined segment of the skin ECG waveform complex.
13. The method for locating according to claim 11 , wherein the method is iteratively executed for successively detected waveform complexes as the indwelling catheter is advanced within the vasculature.