Multisite leadless cardiac resynchronization

A method for stimulating a heart in a living body, the method comprising the steps of:

• transmitting an AM signal at a first frequency at certain first times and an AM signal at a second frequency at certain second times, wherein the first frequency is at least 50 kHz, the second frequency is at least 50 kHz, and the first frequency is different from the second frequency;
• receiving the AM signal at the first frequency at a first position within the heart;
• generating a corresponding first demodulated output signal that stimulates cardiac tissue concurrently with arrival of the AM signal at the first frequency, wherein an output signal that stimulates cardiac tissue is not generated in response to arrival of the AM signal at the second frequency at the first position;
• receiving the AM signal at the second frequency at a second position within the heart;
• generating a corresponding second demodulated output signal that is capable of stimulates cardiac tissue concurrently with arrival of the AM signal at the second frequency, wherein an output signal that stimulates cardiac tissue is not generated in response to arrival of the AM signal at the first frequency at the second position;
• and
• controlling generation, timing, and duration of the AM signal at the first frequency and the AM signal at the second frequency at appropriate times during a cardiac cycle so that while the AM signal at the first frequency and the AM signal at the second frequency are being received at the first and second positions, respectively, the generated first and second demodulated output signals stimulate respective parts of the heart to promote improved cardiac performance.

An apparatus for stimulating designated animal tissue in a living body, the apparatus comprising:

• an AM transmitter having a controllable output frequency, the AM transmitter being configured to generate a first-frequency output signal in response to a first control signal and a second-frequency output signal in response to a second control signal, wherein the first frequency is at least 50 kHz, the second frequency is at least 50 kHz, and the first frequency is different from the second frequency;
• a first AM receiver configured for implantation at a first position within the tissue, wherein the first AM receiver includes a first antenna, at least one first rectifier, and a first filter that is tuned to the first frequency, wherein the first AM receiver is configured to (a) generate a first demodulated output signal that stimulates the tissue concurrently with arrival of the first-frequency output signal at the first antenna and (b) not to generate an output signal that stimulates the tissue in response to arrival of the second-frequency output signal at the first antenna;
• a second AM receiver configured for implantation at a second position within the tissue, wherein the second AM receiver includes a second antenna, at least one second rectifier, and a second filter that is tuned to the second frequency, wherein the second AM receiver is configured to (a) generate a second demodulated output signal that stimulates the tissue concurrently with arrival of the second-frequency output signal at the second antenna and (b) not to generate an output signal that stimulates the tissue in response to arrival of the first-frequency output signal at the second antenna;
• and
• a controller configured to generate the first control signal and the second control signal and to control timing and duration of the generated first and second control signals so that the generated first and second control signals cause the AM transmitter to generate the first-frequency output signal and the second-frequency output signal at appropriate times during an activity of the tissue so that while the first-frequency output signal and the second-frequency output signal are being received by the first AM receiver and the second AM receiver, respectively, the first AM receiver and the second AM receiver generate the respective first and second demodulated output signals that stimulate the tissue.