Methods and apparatus to stimulate the heart
A method and apparatus for treatment of hypertension and heart failure by increasing secretion of endogenous atrial hormones by pacing of the heart. Pacing is done during the ventricular refractory period resulting in premature atrial contraction that does not result in ventricular contraction. Pacing results in the atrial wall stress, peripheral vasodilation, ANP secretion. Concomitant reduction of the heart rate is monitored and controlled as needed with backup pacing.
1. A method for controlling heart contraction to reduce blood pressure, the method comprising:
allowing for a first atrial contraction of an atrium of a heart of a patient;
allowing for a first ventricular contraction of a ventricle of the heart of the patient;
pacing the heart during a pacing period after expiration of an atrial refractory period associated with the first atrial contraction and within a ventricular refractory period associated with the first ventricular contraction; and
causing, by the pacing of the heart during the pacing period, a second atrial contraction without eliciting a corresponding second ventricular contraction.
2. The method of claim 1 , wherein allowing for the first atrial contraction comprises one of sensing the first atrial contraction and pacing the first atrial contraction, and
wherein allowing for the first ventricular contraction comprises one of sensing the first ventricular contraction and pacing the first ventricular contraction.
3. The method of claim 1 , wherein the second atrial contraction causes a vasodilation and a release of natriuretic hormone.
4. The method of claim 1 , wherein the second atrial contraction occurs when the atrium is distended with blood.
5. A method for treating a blood pressure disorder in a patient, the method comprising:
pacing a heart of the patient so as to cause an atrial contraction against a closed heart valve;
causing increased atrial wall stress by the atrial contraction;
causing release of a natriuretic hormone by the increased atrial wall stress; and
reducing the patient's blood pressure from a pretreatment blood pressure by the released natriuretic hormone.
6. A device for controlling heart rate by pacing a heart of a patient having an atrium and a ventricle, the device comprising:
at least one electrically conductive lead configured to connect to the heart of the patient;
an electrical pulse generator connectable to the at least one electrically conductive lead and configured to:
pace, after a first ventricular contraction of the heart, the atrium of the heart, wherein the atrial pace occurs after expiration of an atrial refractory period of the heart and during a ventricular refractory period of the heart, and
cause an atrial contraction as a result of the atrial pace,
wherein the atrial contraction does not elicit a second ventricular contraction.
7. The device of claim 6 , wherein the electrical pulse generator is configured to cause the atrial contraction when the atrium is distended with blood.
8. The device of claim 6 , wherein the atrial contraction causes a vasodilation and a release of a natriuretic hormone in the heart.
9. The device of claim 8 , wherein the electrical pulse generator is configured to monitor a ventricular contraction rate resulting from the atrial pace to determine whether the atrial pace conducts to the ventricle, and to adjust the atrial pace based on the monitoring.
10. The device of claim 8 , wherein the electrical pulse generator is configured to pace the atrium upon expiration of a predetermined delay after the first ventricular contraction.
11. The device of claim 10 , wherein the electrical pulse generator is configured to adjust the predetermined delay based on a detected propagation of the atrial pace to the ventricle.
12. The device of claim 10 , wherein the predetermined delay is between approximately 150 milliseconds and 300 milliseconds after the first ventricular contraction.
13. The device of claim 8 , wherein the electrical pulse generator is configured to monitor a spontaneous heart beat after the electrical pulse generator applies an atrial pacing pulse, and to deliver another atrial pacing pulse if a predetermined delay after the first ventricular contraction is longer than a predetermined period corresponding to a lowest selected heart rate, wherein the another atrial pacing pulse generates ventricular contraction.
14. The device of claim 13 , wherein the lowest selected heart rate is less than approximately 50 beats per minute.
15. The device of claim 8 , wherein the electrical pulse generator is configured to cause the atrial contraction in approximately a middle of ventricular systole.
16. The device of claim 8 , wherein the electrical pulse generator is configured to cause the atrial contraction when an atrioventricular valve between the atrium and the ventricle is closed.
17. The device of claim 8 , wherein the electrical pulse generator is configured to pace a right atrium, a left atrium, or both the left and right atria.
18. The device of claim 8 , wherein during a given cardiac cycle a first atrial contraction occurs followed by the first ventricular contraction, and wherein, in being configured to cause the atrial contraction as a result of the atrial pace, the electrical pulse generator is configured to cause a second atrial contraction after the first atrial contraction and the first ventricular contraction.