Cardiac stimulation apparatus and method for the control of hypertension
A method that electrically stimulates a heart muscle to alter the ejection profile of the heart, to control the mechanical function of the heart and reduce the observed blood pressure of the patient. The therapy may be invoked by an implantable blood pressure sensor associated with a pacemaker like device. In some cases, where a measured pretreatment blood pressure exceeds a treatment threshold, a patient's heart may be stimulated with an electrical stimulus timed relative to the patient's cardiac ejection cycle. This is done to cause dyssynchrony between at least two cardiac chambers or within a cardiac chamber, which alters the patient's cardiac ejection profile from a pretreatment cardiac ejection profile. This has the effect of reducing the patient's blood pressure from the measured pretreatment blood pressure.
1. A method, carried out with an implanted heart muscle stimulator associated with a heart of a patient, for treating a blood pressure disorder in the patient, the method comprising:
determining an intrinsic contraction timing between at least two cardiac chambers of the heart of the patient, wherein the intrinsic contraction timing has an intrinsic atrioventricular delay between intrinsic atrial and ventricular contractions, and an intrinsic heart interval between intrinsic atrial contractions;
after an intrinsic atrial contraction, stimulating a ventricle of the heart after a shortened atrioventricular delay that is shorter than the intrinsic atrioventricular delay, thereby causing a first heartbeat that produces reduced blood flow and reduced blood pressure;
after the first heartbeat, stimulating an atria of the heart after a shortened heart interval that is shorter than the intrinsic heart interval, thereby causing an early atrial contraction and providing an increased heartbeats per unit time to maintain cardiac output of the heart;
after the early atrial contraction, allowing a second heartbeat to occur intrinsically following the intrinsic atrioventricular delay, wherein the second heartbeat produces reduced blood flow and reduced blood pressure; and
after the second heartbeat, stimulating the atria of the heart after a shortened heart interval that is shorter than the intrinsic heart interval and then stimulating the ventricle of the heart after a shortened atrioventricular delay that is shorter than the intrinsic atrioventricular delay, thereby causing a third heartbeat that produces reduced blood flow and reduced blood pressure.
2. The method of claim 1 , further comprising stimulating the atria and the ventricle to alternately reproduce the second heartbeat and the third heartbeat.
3. The method of claim 2 , wherein following an alternately reproduced second heartbeat and third heartbeat, the method further comprises stimulating the atria and the ventricle to reproduce the second heartbeat followed by one or more intrinsic heartbeats.
4. The method of claim 3 , further comprising receiving blood pressure data, and based on the blood pressure data, reducing blood pressure by decreasing a number of intrinsic heartbeats and/or by increasing a number of alternating second and third heartbeats.
5. The method of claim 1 , wherein the patient has a pretreatment systemic blood pressure corresponding to a pretreatment cardiac ejection profile,
wherein after the second heartbeat, stimulating the atria of the heart after the shortened atrioventricular delay causes between the at least two cardiac chambers of the heart a dyssynchronous contraction timing that varies from the intrinsic contraction timing, and
wherein the dyssynchronous contraction timing between the at least two cardiac chambers alters cardiac ejection profile of the patient from the pretreatment cardiac ejection profile and reduces systemic blood pressure of the patient from the pretreatment systemic blood pressure.
6. A method, carried out with an implanted heart muscle stimulator associated with a heart of a patient, for treating a blood pressure disorder in the patient, the method comprising:
determining an intrinsic contraction timing between at least two cardiac chambers of the heart of the patient, wherein the intrinsic contraction timing has an intrinsic atrioventricular delay between intrinsic atrial and ventricular contractions, and an intrinsic heart interval between intrinsic atrial contractions;
allowing an intrinsic heartbeat to occur;
following the intrinsic heartbeat, stimulating the heart to produce a first heartbeat having a shortened atrioventricular delay relative to the intrinsic atrioventricular delay;
following the first heartbeat, stimulating the heart to produce a second heartbeat having a shortened heart interval relative to the intrinsic heart interval, so as to provide an increased heartbeats per unit time to maintain cardiac output; and
following the second heartbeat, stimulating the heart to produce a third heartbeat having a shortened heart interval relative to the intrinsic delay and a shortened atrioventricular delay relative to the intrinsic atrioventricular delay.
7. The method of claim 6 , wherein the patient has a pretreatment systemic blood pressure corresponding to a pretreatment cardiac ejection profile,
wherein following the second heartbeat, stimulating the atria of the heart after the shortened atrioventricular delay causes between the at least two cardiac chambers of the heart a dyssynchronous contraction timing that varies from the intrinsic contraction timing, and
wherein the dyssynchronous contraction timing between the at least two cardiac chambers alters cardiac ejection profile of the patient from the pretreatment cardiac ejection profile and reduces systemic blood pressure of the patient from the pretreatment systemic blood pressure.
8. A method, carried out with an implanted heart muscle stimulator associated with a heart of a patient, for treating a blood pressure disorder in the patient, the method comprising:
determining an intrinsic atrioventricular delay between an intrinsic atrial contraction of an atrium of the heart and an intrinsic ventricular contraction of a ventricle of the heart,
determining an intrinsic heart interval between a first intrinsic atrial contraction of the atrium and a next second intrinsic atrial contraction of the atrium,
causing in the heart at least one first heartbeat having a shortened atrioventricular delay that is shorter than the intrinsic atrioventricular delay and reduces blood pressure, by stimulating the heart with an electrical stimulus from the implanted heart muscle stimulator; and
causing in the heart at least one second heartbeat having a shortened heart interval that is shorter than the intrinsic heart interval and increases heartbeats per unit time over intrinsic heartbeats per unit time to maintain cardiac output, by stimulating the heart with an electrical stimulus from the implanted heart muscle stimulator.
9. The method of claim 8 , wherein the intrinsic heart interval is approximately 800 milliseconds, and wherein the shortened heart interval of the at least one second heartbeat is approximately 700 milliseconds.
10. The method of claim 8 , wherein the at least one first heartbeat has a shortened heart interval that is shorter than the intrinsic heart interval.
11. The method of claim 8 , further comprising receiving blood pressure data, and based on the blood pressure data, setting the shortened atrioventricular delay to achieve a desired blood pressure reduction and setting the shortened heart interval to compensate for the desired blood pressure reduction and maintain cardiac output.
12. The method of claim 8 , wherein the intrinsic atrioventricular delay is approximately 200 milliseconds, and wherein the shortened atrioventricular delay is approximately 125 milliseconds.
13. The method of claim 8 , wherein the at least one first heartbeat has the intrinsic heart interval.
14. The method of claim 8 , wherein the at least one second heartbeat has the intrinsic atrioventricular delay.
15. The method of claim 8 , further comprising delivering to the heart using the implanted heart muscle stimulator a stimulation pattern comprising alternating between causing the at least one first heartbeat and causing the at least one second heartbeat.
16. An implantable heart muscle stimulator apparatus for treating a blood pressure disorder in a patient, the apparatus comprising:
at least one lead configured to be in electrical communication with a cardiac chamber of a heart of the patient; and
an electrical stimulation device in electrical communication with the at least one lead and comprising a non-transitory computer-readable medium programmed to:
determine an intrinsic atrioventricular delay between an intrinsic atrial contraction of an atrium of the heart and an intrinsic ventricular contraction of a ventricle of the heart,
determine an intrinsic heart interval between a first intrinsic atrial contraction of the atrium and a next second intrinsic atrial contraction of the atrium, and
deliver through the at least one lead a stimulation pattern comprising alternating between a first stimulation and a second stimulation,
wherein the first stimulation is configured to cause in the heart at least one first heartbeat having a shortened atrioventricular delay that is shorter than the intrinsic atrioventricular delay and reduces blood pressure, and
wherein the second stimulation is configured to cause in the heart at least one second heartbeat having a shortened heart interval that is shorter than the intrinsic heart interval and increases heartbeats per unit time over intrinsic heartbeats per unit time to maintain cardiac output.
17. The apparatus of claim 16 , wherein the intrinsic heart interval is approximately 800 milliseconds, and wherein the shortened heart interval of the at least one second heartbeat is approximately 700 milliseconds.
18. The apparatus of claim 16 , wherein the intrinsic atrioventricular delay is approximately 200 milliseconds, and wherein the shortened atrioventricular delay is approximately 125 milliseconds.
19. The apparatus of claim 16 , wherein the at least one first heartbeat has the intrinsic heart interval.
20. The apparatus of claim 16 , wherein the at least one second heartbeat has the intrinsic atrioventricular delay.
21. The apparatus of claim 16 , wherein the at least one first heartbeat has a shortened heart interval that is shorter than the intrinsic heart interval.
22. The apparatus of claim 16 , wherein the non-transitory computer-readable medium is further programmed with logic to receive blood pressure data, and based on the blood pressure data, set the shortened atrioventricular delay to achieve a desired blood pressure reduction and set the shortened heart interval to compensate for the desired blood pressure reduction and maintain cardiac output.