Methods and systems for controlling blood pressure by controlling atrial pressure
Systems and methods for controlling blood pressure by controlling atrial pressure and atrial stretch are disclosed. In some embodiments, a stimulation circuit may be configured to deliver a stimulation pulse to at least one cardiac chamber of a heart of a patient, and at least one controller may be configured to execute delivery of one or more stimulation patterns of stimulation pulses to the at least one cardiac chamber, wherein at least one of the stimulation pulses stimulates the heart such that an atrial pressure resulting from atrial contraction of an atrium overlaps in time a passive pressure build-up of the atrium, such that an atrial pressure of the atrium resulting from the stimulation is a combination of the atrial pressure resulting from atrial contraction and the passive pressure build-up and is higher than an atrial pressure of the atrium would be without the stimulation, and such that the blood pressure of the patient is reduced.
1. A system for reducing blood pressure in a patient, the system comprising:
a stimulation circuit configured to deliver a stimulation pulse to at least one cardiac chamber of a heart of the patient; and
at least one controller configured to execute delivery of one or more stimulation patterns of stimulation pulses to the at least one cardiac chamber,
wherein at least one of the stimulation pulses stimulates the heart to cause increased atrial stretch of a wall of an atrium as a result of timing of atrial contraction and ventricular contraction, and
wherein the increased atrial stretch is higher than an atrial stretch would be without the stimulation, such that the blood pressure of the patient is reduced.
2. The system of claim 1 , wherein the increased atrial stretch reduces blood pressure through at least one of hormonal pathways or neural pathways.
3. The system of claim 1 , wherein, to cause the increased atrial stretch, the at least one of the stimulation pulses stimulates the heart such that the atrium contracts when pressure in a ventricle of the heart is about maximal so that active force of the atrial contraction increases atrial stretch above maximal passive atrial stretch caused by the ventricular contraction.
4. The system of claim 1 , wherein, to cause the increased atrial stretch, the at least one of the stimulation pulses stimulates a ventricle of the heart to cause the ventricle to commence contraction at such timing that peak atrial contraction occurs when the ventricle is near or at maximal stretch.
5. The system of claim 1 , wherein the at least one controller is configured to determine atrial stretch by measuring changes in dimension of the atrium.
6. The system of claim 1 , wherein, to cause the increased atrial stretch, the at least one of the stimulation pulses stimulates the heart to control timing of valve closure relative to atrial contraction.
7. The system of claim 1 , wherein the controller is configured to deliver the one or more stimulation patterns for a predetermined time interval, and to cause the increased atrial stretch to occur for a portion of the predetermined time interval.
8. The system of claim 1 , wherein the increased atrial stretch occurs transiently during the stimulation.
9. The system of claim 1 , wherein, to cause the increased atrial stretch, the at least one of the stimulation pulses stimulates the heart such that an atrial stretch resulting from atrial contraction overlaps in time a passive atrial stretch.
10. The system of claim 9 , wherein the passive atrial stretch occurs during isovolumic contraction of a ventricle of the heart.
11. The system of claim 9 , wherein the passive atrial stretch occurs during a rapid ejection phase of a ventricle of the heart.
12. The system of claim 1 , wherein, to cause the increased atrial stretch, the at least one of the stimulation pulses stimulates the heart such that a maximum of atrial pressure resulting from atrial contraction overlaps in time a maximum passive atrial stretch.
13. The system of claim 12 , wherein the maximum passive atrial stretch occurs at a time between about 25 ms after start of an isovolumic phase and about 10 ms after end of the isovolumic phase.
14. The system of claim 12 , wherein the maximum passive atrial stretch occurs between a start of a second half of an isovolumic phase and a first approximately 10 ms of a rapid ejection phase.
15. The system of claim 1 , wherein the one or more stimulation patterns comprise pacing the atrium and a ventricle of the heart at a substantially equal rate.
16. The system of claim 1 , wherein the one or more stimulation patterns comprise pacing the atrium at a rate higher than a rate at which a ventricle of the heart is paced.
17. The system of claim 1 , wherein the at least one of the stimulation pulses comprises stimulating the atrium of the heart such that the atrium contracts only once during a single cardiac cycle.
18. The system of claim 1 , wherein the timing corresponds to an atrioventricular delay of between approximately 60 ms and approximately 0 ms.
19. A method, carried out with an implanted heart muscle stimulator associated with a heart of a patient, for reducing blood pressure of the patient, the method comprising:
delivering one or more stimulation patterns of stimulation pulses to at least one cardiac chamber of the heart of the patient; and
stimulating the heart with at least one of the stimulation pulses to cause increased atrial stretch of a wall of an atrium as a result of timing of atrial contraction and ventricular contraction,
wherein the increased atrial stretch is higher than an atrial stretch would be without the stimulation, such that the blood pressure of the patient is reduced.
20. The method of claim 19 , wherein, to cause the increased atrial stretch, the at least one of the stimulation pulses stimulates the heart such that the atrium contracts when pressure in a ventricle of the heart is about maximal so that active force of the atrial contraction increases atrial stretch above maximal passive atrial stretch caused by the ventricular contraction.
21. A system for reducing blood pressure in a patient, the system comprising:
a stimulation circuit configured to deliver a stimulation pulse to at least one cardiac chamber of a heart of the patient; and
at least one controller configured to execute delivery of one or more stimulation patterns of stimulation pulses to the at least one cardiac chamber,
wherein at least one of the stimulation pulses stimulates the heart to provide a timing of atrial contraction and ventricle contraction that increases atrial stretch, and
wherein the increased atrial stretch is higher than an atrial stretch would be without the stimulation, such that the blood pressure of the patient is reduced.
22. The system of claim 21 , wherein the at least one of the stimulation pulses stimulates the heart such that a maximum of atrial stretch resulting from atrial contraction overlaps in time a maximum passive atrial stretch.