Ablation condition determination methods and systems
A method and apparatus are disclosed for determining if a previously carried out heart ablation has been effective in isolating tissue. The method involves inserting an esophageal device, e.g. a catheter, into the esophagus so that an electrode is adjacent the heart, pacing the electrode with an electrical pacing signal, and determining if the heart adopts the pacing signal. Adoption of the pacing signal is indicative of the tissue not being electrically isolated by the ablation, and so may signal that a re-ablation procedure is necessary. Non adoption of the pacing signal is indicative of the tissue being electrically isolated by the ablation. Also disclosed is a processing unit for comparing a measured heart signal with a predetermined pacing signal to determine heart adoption of the pacing signal. The device and processing unit may be used to measure natural heart signals in the esophagus to assist in correct catheter positioning.
1. A method of determining a condition of a previously established heart ablation, said method comprising:
inserting an elongate esophageal device comprising an electrode into an esophagus of a subject whose heart possesses the previously established heart ablation;
applying a predetermined pacing to the electrode of the elongate esophageal device;
monitoring a heart rate of the subject to determine if the predetermined pacing is adopted by a heart of the subject; and
in the event that the predetermined pacing is not adopted by the heart, determining that the heart ablation is effective.
2. The method of claim 1 , further comprising:
after inserting the elongate esophageal device into the esophagus and before applying the predetermined pacing to the electrode, positioning the electrode of the device in the esophageal lumen at a location adjacent the myocardial wall of the heart.
3. The method of claim 2 , comprising imaging an area including the device electrode and the heart.
4. The method of claim 3 , wherein said imaging comprises X-ray fluoroscopy.
5. The method of claim 2 , wherein the electrode of the device is positioned in the esophageal lumen at a location adjacent the left atrium of the heart.
6. The method of claim 1 , wherein said predetermined pacing is performed with a current of between 5 and 35 mA.
7. The method of claim 6 , wherein said predetermined pacing is performed with a current of between 15 and 25 mA.
8. The method of claim 1 , wherein said predetermined pacing is performed with a frequency of between 70 and 150 pulses/minute.
9. The method of claim 8 , wherein said predetermined pacing is performed with a frequency of between 90 and 110 pulses/minute.
10. The method of claim 1 , further comprising:
in the event that the predetermined pacing is adopted by the heart, determining that the heart ablation is not effective.
11. The method of claim 1 , wherein said predetermined pacing is performed with a frequency above a spontaneous heart rate of the subject.
12. The method of claim 1 , wherein a unit is provided that receives a signal corresponding to the heart rate and compares the signal to the predetermined pacing so as to provide a signal indicative of whether the heart has adopted the predetermined pacing or not.
13. A method of determining a condition of a previously established heart ablation, said method comprising:
inserting an esophageal device into an esophagus of a subject whose heart possesses the previously established heart ablation;
applying an electrical signal to the esophageal device at a location near to the heart of the subject;
monitoring the heart of the subject to determine if the heart reacts to the electrical signal; and
in the event that the heart does not react to the electrical signal, determining that the heart ablation is effective.
14. The method of claim 13 , wherein monitoring the heart of the subject to determine if the heart reacts to the electrical signal comprises comparing a predetermined pacing rate of the electrical signal to a heart rate of the subject.