Mapping sympathetic nerve distribution for renal ablation and catheters for same
This invention provides methods for mapping and ablating renal nerves to treat disease caused by systemic renal nerve hyperactivity, e.g. hypertension, heart failure, renal failure and diabetes. Also provided are catheters for performing the mapping and ablating functions.
1. A method of mapping a sympathetic renal nerve for treatment of disease caused by systemic renal nerve hyperactivity, comprising the steps of:
a) introducing a catheter into the lumen of a renal artery such that a tip of said catheter contacts a site on the inner renal artery wall;
b) measuring one or more physiological parameters to obtain baseline measurements before introducing an electrical current to the site, said physiological parameters are selected from the group consisting of systolic blood pressure, diastolic blood pressure, mean arterial pressure, and heart rate;
c) applying electrical stimulation by introducing said electrical current to the site via the catheter, wherein said electrical current is controlled to be sufficient to elicit an increase in said physiological parameters when there is an underlying nerve at the site; and
d) measuring said physiological parameters at a specific time interval after each electrical stimulation, wherein said increase of said physiological parameters over the baseline measurements after said electrical stimulation would indicate that said sympathetic renal nerve has been mapped at said site.
2. The method of claim 1 , wherein said catheter is an ablative catheter designed to treat cardiac arrhythmias.
3. The method of claim 1 , wherein said catheter is an ablative catheter designed specifically for mapping renal nerves for ablative procedures.
4. The method of claim 1 , wherein said specific time interval in step (d) is from about 5 seconds to about 2 minutes.
5. The method of claim 1 , wherein said one or more physiological parameters includes said systolic blood pressure, and said increase in systolic blood pressure is in the range of 4 to 29 mmHg.
6. The method of claim 1 , wherein said one or more physiological parameters includes said diastolic blood pressure, and said increase in diastolic blood pressure is in the range of 1.5 to 20 mmHg.
7. The method of claim 1 , wherein said one or more physiological parameters includes said mean arterial pressure, and said increase in mean arterial pressure is in the range of 3 to 17 mmHg.
8. The method of claim 1 , wherein said one or more physiological parameters includes said heart rate, and said increase in heart rate is in the range of 4 to 12 beats/min.
9. The method of claim 1 , wherein the electrical current sufficient to elicit changes in the physiological parameters comprises one or more of the following parameters:
(a) voltage of between 2 and 30 volts;
(b) resistance of between 100 and 1000 ohms;
(c) current of between 5 and 40 miliamperes; or
(d) applied between 0.1 and 20 milliseconds.
10. The method of claim 1 , further comprising a step of applying radiofrequency energy through the catheter to the site identified in step (d) for ablation of the underlying nerve to treat disease caused by systemic renal nerve hyperactivity.