Methods and systems for lowering blood pressure through reduction of ventricle filling
Methods and devices for reducing ventricle filling volume are disclosed. In some embodiments, an electrical stimulator may be used to stimulate a patient's heart to reduce ventricle filling volume or even blood pressure. When the heart is stimulated in a consistent way to reduce blood pressure, the cardiovascular system may over time adapt to the stimulation and revert back to the higher blood pressure. In some embodiments, the stimulation pattern may be configured to be inconsistent such that the adaptation response of the heart is reduced or even prevented. In some embodiments, an electrical stimulator may be used to stimulate a patient's heart to cause at least a portion of an atrial contraction to occur while the atrioventricular valve is closed. Such an atrial contraction may deposit less blood into the corresponding ventricle than when the atrioventricular valve is opened throughout an atrial contraction.
1. A system for reducing blood pressure comprising:
at least one stimulation electrode for stimulating at least one chamber of a heart of a patient; and
at least one controller configured to execute a stimulation pattern comprising at least one stimulation pulse having at least one stimulation setting configured to reduce or prevent atrial kick in at least one ventricle of the heart,
wherein the at least one stimulation setting is configured such that maximum atrial stretch is at a value that is about equal to or lower than maximum atrial stretch of the heart when not receiving stimulation, and
wherein the at least one stimulation setting is configured to cause an atrium of the heart to be at maximum contraction when an atrioventricular valve of the heart is open.
2. The system of claim 1 , wherein the at least one stimulation setting comprises a first stimulation setting and a second stimulation setting, and
wherein the first stimulation setting has an atrioventricular delay different from an atrioventricular of the second stimulation setting.
3. The system of claim 1 , wherein the at least one stimulation setting is configured to alter mechanics of at least one atrial contraction of the heart such that the mechanics of the at least one atrial contraction are different from mechanics of a previous natural atrial contraction of the heart.
4. The system of claim 1 , wherein the at least one stimulation setting comprises a first stimulation setting and a second stimulation setting, and
wherein the first stimulation setting and the second stimulation setting are configured to cause an atrium of the heart to be at maximum contraction when an atrioventricular valve of the heart is open.
5. A system for reducing blood pressure comprising:
at least one stimulation electrode for stimulating at least one chamber of a heart of a patient; and
at least one controller configured to execute a stimulation pattern comprising at least one stimulation pulse having at least one stimulation setting configured to reduce or prevent atrial kick in at least one ventricle of the heart,
wherein the at least one stimulation setting is configured such that maximum atrial stretch is at a value that is about equal to or lower than maximum atrial stretch of the heart when not receiving stimulation, and
wherein the at least one stimulation setting is configured to prevent at least one atrial contraction of the heart.
6. A system for reducing blood pressure comprising:
at least one stimulation electrode for stimulating at least one chamber of a heart of a patient; and
at least one controller configured to:
execute a stimulation pattern of stimulation pulses to the heart of the patient;
receive input relating to the patient's atrioventricular valve status; and
adjust the at least one stimulation pattern based on the atrioventricular valve status.
7. The system of claim 6 , wherein the input relating to the patient's atrioventricular valve status is indicative of timing of closure of the atrioventricular valve.
8. The system of claim 6 , wherein the input relating to the patient's atrioventricular valve status is provided based on a heart sound sensor.
9. The system of claim 6 , wherein the input relating to the patient's atrioventricular valve status is provided based on a blood flow sensor.
10. The system of claim 9 , wherein the blood flow sensor includes an implanted sensor.
11. The system of claim 9 , wherein the blood flow sensor includes an ultrasound sensor for sensing blood flow through the atrioventricular valve.
12. The system of claim 9 , wherein the blood flow sensor and the at least one controller are configured to operate at least partially as a closed loop.
13. The system of claim 6 , wherein the stimulation pattern comprises at least one stimulation pulse configured to reduce or prevent atrial kick in at least one ventricle of the heart of the patient.
14. The system of claim 13 , wherein the at least one controller, in being configured to adjust the at least one stimulation pattern, is configured to adjust the atrioventricular delay of at least one stimulation pulse.
15. A method for reducing blood pressure of a patient, the method comprising:
measuring a pretreatment blood pressure of the patient;
applying a first blood pressure reducing stimulation pattern to at least one chamber of a heart of the patient;
measuring, during delivery of the first blood pressure reducing stimulation pattern, a first treatment blood pressure of the patient;
discontinuing application of the first blood pressure reducing stimulation pattern;
measuring, after discontinuing application of the first blood pressure reducing stimulation pattern, a first maximum post-treatment blood pressure of the patient;
comparing the pretreatment blood pressure to the first maximum post-treatment blood pressure;
when the first maximum post-treatment blood pressure is greater than the pretreatment blood pressure, adjusting the first blood pressure reducing stimulation pattern to a second blood pressure reducing stimulation pattern that is configured to provide a second maximum post-treatment blood pressure when application of the second blood pressure reducing stimulation pattern is discontinued, wherein the second maximum post-treatment blood pressure is less than the first maximum post-treatment blood pressure; and
applying the second blood pressure reducing stimulation pattern to the at least one chamber of the heart.
16. The method of claim 15 , wherein the first maximum post-treatment blood pressure occurs within about 10 seconds after discontinuing application of the first blood pressure reducing stimulation pattern.
17. The method of claim 15 , wherein the second blood pressure reducing stimulation pattern is configured to achieve a desired reduction in blood pressure.
18. The method of claim 17 , wherein the desired reduction in blood pressure comprises at least one of a given percentage reduction, a given measure, a given range, or a given target.
19. The method of claim 15 , wherein when the first maximum post-treatment blood pressure is greater than the pretreatment blood pressure, adjusting the first blood pressure reducing stimulation pattern to the second blood pressure reducing stimulation pattern comprises adjusting the first blood pressure reducing stimulation pattern to a second blood pressure reducing stimulation pattern that is configured to provide a second maximum post-treatment blood pressure that is less than the pretreatment blood pressure.
20. The method of claim 19 , wherein the second blood pressure reducing stimulation pattern is configured to achieve a desired reduction in blood pressure.
21. The method of claim 15 , wherein adjusting the first blood pressure reducing stimulation pattern comprises adjusting one or more of atrioventricular delay, a number of stimulation pulses, or a time of stimulation pulses.
22. The method of claim 15 , wherein the second blood pressure reducing stimulation pattern comprises a first number of blood pressure reducing pulses each delivered at a first atrioventricular delay, followed by a second number of blood pressure reducing pulses each delivered at a second atrioventricular delay,
wherein the first number is greater than the second number, and
wherein the second atrioventricular delay is longer than the first atrioventricular delay.
23. The method of claim 15 , wherein adjusting the first blood pressure reducing stimulation pattern comprises:
calculating a time constant of change in blood pressure; and
adjusting the first blood pressure reducing stimulation pattern to have one or more blood pressure reducing stimulation parameters for an amount of time or number of heartbeats that are set as a certain percentage of the calculated time constant and that are configured to prevent blood pressure of the patient from increasing beyond a given value.
24. The method of claim 23 , wherein the amount of time is within a range of about 30-60% of the time constant of change in blood pressure.
25. A method for reducing blood pressure of a patient, the method comprising:
measuring a pretreatment blood pressure of the patient;
delivering to at least one chamber of a heart of the patient a first stimulation pattern that reduces blood pressure, wherein the first stimulation pattern has a first time response constant;
discontinuing delivering of the first stimulation pattern and observing an overshoot in blood pressure of the patient; and
delivering to the at least one chamber a second stimulation pattern that reduces blood pressure, wherein the second stimulation pattern has a second time response constant that, when discontinued, limits blood pressure overshoot to below the overshoot in blood pressure observed during discontinuing delivering of the first stimulation pattern.
26. The method of claim 25 , wherein the second time response constant of the second stimulation pattern is greater than the first time response constant of the first stimulation pattern.
27. The method of claim 26 , wherein the second time response constant is at least about three times greater than the first time response constant.
28. The method of claim 25 , wherein the overshoot in blood pressure observed during discontinuing delivering of the first stimulation pattern rises above a resting blood pressure to which the patient returns following discontinuing of the first stimulation pattern.
29. The method of claim 25 , wherein the first stimulation pattern comprises at least one stimulation pulse configured to reduce or prevent atrial kick in at least one ventricle of the heart of the patient.
30. The method of claim 25 , wherein the second stimulation pattern is set to have one or more blood pressure reducing stimulation parameters for an amount of time or number of heartbeats that are set as a certain percentage of the second time response constant and that are configured to prevent blood pressure from increasing beyond a given value.