Methods for improving heart function
The invention provides methods related to improving heart function.
1. A method of treating heart failure, comprising:
inducing dyssynchronous contractions of a ventricle in a subject suffering from heart failure, wherein at least part of the ventricle contracts dyssynchronously relative to another part of the subject's ventricle, wherein the dyssynchronous contractions are induced using a device, comprising:
a power source;
an atrial stimulation electrode operably connected to an atrium of the subject's heart;
a ventricular stimulation electrode operably connected to the ventricle of the subject's heart; and
a controller that is:
operably connected to the power source and to the stimulation electrodes;
configured to receive a signal indicative of atrial electrical activity; and
programmed to:
monitor the signal to detect an atrial heart rate;
operate the device in a normal pacing mode, for which the controller is programmed to cause the atrial stimulation electrode to depolarize atrial tissue of the subject if the atrial heart rate is below a predetermined limit; and
periodically transiently operate the device in a dyssynchrony-inducing mode, for which the controller is programmed to cause the ventricular stimulation electrode to depolarize ventricular tissue of the subject at a single site with a delay relative to atrial electrical activity shorter than a normal atrioventricular conduction delay; alternate between the normal pacing mode and the dyssynchrony-inducing mode in a cycle; and have a cycle length of at least one month; or
operate the device in a dyssynchrony-inducing mode, for which the controller is programmed to cause the ventricular stimulation electrode to depolarize ventricular tissue of the subject at a single site with a delay relative to atrial electrical activity shorter than a normal atrioventricular conduction delay; and
periodically apply the dyssynchrony-inducing mode for a period of time of at least a few hours sufficient to stimulate molecular signaling changes that are subsequently modified by reinstating normal pacing;
periodically transiently operating the device in the dyssynchrony-inducing mode to cause the ventricular stimulation electrode to depolarize the ventricular tissue of the subject at the single site with the delay relative to atrial electrical activity shorter than the normal atrioventricular conduction delay;
maintaining the dyssynchronous contractions for a period of time;
alternating between the normal pacing mode and the dyssynchrony-inducing mode in the cycle, wherein the cycle length is of at least the one month; and
restoring synchronous contractions of the subject's ventricle.
2. A method of treating heart failure, comprising:
inducing dyssynchronous contractions of a ventricle in a subject suffering from heart failure, wherein at least part of the ventricle contracts dyssynchronously relative to another part of the subject's ventricle, wherein the dyssynchronous contractions are induced using a device, comprising:
a power source;
an atrial stimulation electrode operably connected to an atrium of the subject's heart;
a ventricular stimulation electrode operably connected to the ventricle of the subject's heart; and
a controller that is:
operably connected to the power source and to the stimulation electrodes;
configured to receive a signal indicative of atrial electrical activity; and
programmed to:
monitor the signal to detect an atrial heart rate;
operate the device in a normal pacing mode, for which the controller is programmed to cause the atrial stimulation electrode to depolarize atrial tissue of the subject if the atrial heart rate is below a predetermined limit; and
periodically transiently operate the device in a dyssynchrony-inducing mode, for which the controller is programmed to cause the ventricular stimulation electrode to depolarize ventricular tissue of the subject at a single site with a delay relative to atrial electrical activity shorter than a normal atrioventricular conduction delay;
alternate between the normal pacing mode and the dyssynchrony-inducing mode in a cycle; and have a cycle length of at least one month;
maintaining the dyssynchronous contractions for a period of time; and
restoring synchronous contractions of the subject's ventricle.
3. The method of claim 2 , wherein dyssynchronous contractions are induced by periodically applying ventricular pacing to the subject.
4. The method of claim 3 , wherein the ventricular pacing is timed to the subject's atrial electrical activity and applied with a delay relative to the atrial electrical activity that is shorter than a normal atrioventricular conduction delay, thereby causing at least part of the subject's ventricle to contract dyssynchronously relative to another part of the subject's ventricle that is stimulated to contract by normal atrioventricular conduction.
5. The method of claim 4 , wherein the ventricular pacing is applied at no more than one site.
6. The method of claim 5 , wherein the one site is a left-ventricular site.
7. The method of claim 5 , wherein the one site is a right-ventricular site.
8. The method of claim 3 , wherein non-ventricular pacing is applied when the ventricular pacing is not being applied.
9. The method of claim 2 , wherein induced dyssynchronous contractions are maintained for a period of time of at least a few hours sufficient to stimulate molecular signaling changes that are subsequently modified by restoring synchronous contractions.
10. The method of claim 2 , further comprising alternating between induced dyssynchronous contractions and restored synchronous contractions to provide repeated periods of resynchronization following induced dyssynchrony.
11. The method of claim 2 , wherein induced dyssynchronous contractions are maintained during nighttime, and restored synchronous contractions are maintained for the rest of each day.
12. The method of claim 2 , comprising monitoring the signal to detect the atrial heart rate.
13. The method of claim 2 , comprising operating the device in a normal pacing mode to cause the atrial stimulation electrode to depolarize the atrial tissue of the subject if the atrial heart rate is below the predetermined limit.
14. The method of claim 2 , comprising:
periodically transiently operating the device in the dyssynchrony-inducing mode to cause the ventricular stimulation electrode to depolarize the ventricular tissue of the subject at the single site with the delay relative to atrial electrical activity shorter than the normal atrioventricular conduction delay; and,
alternating between the normal pacing mode and the dyssynchrony-inducing mode in the cycle, wherein the cycle length is of at least the one month.
15. The method of claim 2 , comprising:
operating the device in the dyssynchrony-inducing mode to cause the ventricular stimulation electrode to depolarize the ventricular tissue of the subject at the single site with the delay relative to atrial electrical activity shorter than the normal atrioventricular conduction delay; and,
periodically applying the dyssynchrony-inducing mode for the period of time of at least the few hours sufficient to stimulate the molecular signaling changes that are subsequently modified by reinstating the normal pacing.
16. A method of treating heart failure, comprising:
inducing dyssynchronous contractions of a ventricle in a subject suffering from heart failure, wherein at least part of the ventricle contracts dyssynchronously relative to another part of the subject's ventricle, wherein the dyssynchronous contractions are induced using a device, comprising:
a power source;
an atrial stimulation electrode operably connected to an atrium of the subject's heart;
a ventricular stimulation electrode operably connected to the ventricle of the subject's heart; and
a controller that is:
operably connected to the power source and to the stimulation electrodes;
configured to receive a signal indicative of atrial electrical activity; and
programmed to:
monitor the signal to detect an atrial heart rate;
operate the device in a dyssynchrony-inducing mode, for which the controller is programmed to cause the ventricular stimulation electrode to depolarize ventricular tissue of the subject at a single site with a delay relative to atrial electrical activity shorter than a normal atrioventricular conduction delay; and
periodically apply the dyssynchrony-inducing mode for a period of time of at least a few hours sufficient to stimulate molecular signaling changes that are subsequently modified by reinstating normal pacing;
periodically transiently operating the device in the dyssynchrony-inducing mode to cause the ventricular stimulation electrode to depolarize the ventricular tissue of the subject at the single site with the delay relative to atrial electrical activity shorter than the normal atrioventricular conduction delay;
maintaining the dyssynchronous contractions for a period of time;
alternating between the normal pacing mode and the dyssynchrony-inducing mode in the cycle, wherein the cycle length is of at least the one month; and
restoring synchronous contractions of the subject's ventricle.