Transmitting and receiving antennas for transferring power to implanted medical devices
Systems, devices and methods are provided for supporting cardiac function. One system comprises an implantable intracardiac device comprising a motor and a pump, an external energy source and a transmitting resonator comprising a magnetic coil and configured to receive a first level of power from the external energy source and transmit a second level of power through an outer skin surface of the patient. The system further comprises a receiving resonator configured for implantation within the patient, comprising a magnetic coil and configured to transmit a third level of power to the motor within the implanted device. The third level of power is at least 40% of the first level of power, thereby ensuring that the pump will continuously pump blood through the heart at a sufficient rate regardless of any changes in the system, such as power loss due to transmission inefficiencies and/or changes in the relative positions between the transmitting and receiving coils.
1 . A system for supporting cardiac function in a patient, the system comprising:
a housing configured for implantation into a human heart or vascular system, the housing comprising a motor and a pump, wherein the pump comprises a rotor disposed within the housing and spaced from an internal surface of the housing to define a clearance therebetween, an impeller coupled to the rotor for impelling blood from the inlet to the outlet of the housing and a fluid bearing suspending the impeller and the rotor within the housing, wherein the housing comprises an inlet and an outlet and defines a primary blood flow path between the inlet and the outlet, and further comprising a second inlet for blood within the housing fluidly coupled to the clearance between the rotor and the housing to define a secondary flow path through the clearance and wherein the primary blood flow path has a first mass flow rate and the secondary blood flow path has a second mass flow rate, wherein the second mass flow rate is 1% to 20% of the first mass flow rate;
an external power source;
a transmitting antenna coupled to the external power source and comprising at least one magnetic coil, wherein the external power source transmits a first level of power to the transmitting antenna and the transmitting antenna is configured to transmit a second level of power through an outer skin surface of the patient;
a receiving antenna configured for implantation within the patient, the receiving antenna comprising at least one magnetic coil and being configured to receive the second level of power and to transmit a third level of power to the housing, wherein the third level of power is at least 40% of the first level of power.
2 . The system of claim 1 , wherein the third level of power is at least 50% of the first level of power.
3 . The system of claim 1 , further comprising a controller coupled to the transmitting antenna and configured to control the transmitting and receiving antenna such that the third level of power remains at or above a threshold level.
4 . The system of claim 3 , wherein the controller maintains the third level of power at least 50% of the first level of power when the transmitting is moved a distance towards or away from the receiving coil.
5 . The system of claim 4 , wherein the distance is 4 cm.
6 . The system of claim 3 , wherein the controller is configured to maintain the third level of power constant.
7 . The system of claim 1 , wherein the controller maintains the third level of power at least 50% of the first level of power when a center of the transmitting coil is offset a distance from a center of the receiving coil.
8 . The system of claim 7 , wherein the distance is 4 cm.
9 . The system of claim 1 , wherein the first level of power is 10 Watts to 40 Watts.
10 . The system of claim 1 , wherein the second level of power is 15 Watts to 30 Watts.
11 . The system of claim 1 , wherein the third level of power is 5 Watts to 20 Watts.
12 . The system of claim 1 , wherein the transmitting and receiving coils are configured to have a specific absorption rate (SAR) in an touter skin surface of the patient of 1.5 Watts/kg or less.
13 . The system of claim 1 , wherein the transmitting coil is flexible.
14 . The system of claim 1 , wherein the transmitting coil comprises an outer surface and a spiral winding on the outer surface.
15 . The system of claim 14 , wherein the spiral winding comprises first and second discontinuous windings, wherein the first winding is-concentric with the second winding.
16 . The system of claim 1 , wherein the receiving coil comprises an outer surface and a spiral winding on the outer surface.
17 . The system of claim 16 , wherein the spiral winding is continuous.
18 . The system of claim 16 , wherein the spiral winding comprises first and second discontinuous windings, wherein the first winding is concentric with the second winding.
19 . The system of claim 1 , further comprising a receiving resonator disposed within the housing.
20 . The system of claim 1 , further comprising a wearable device configured to be attached to, or worn by, the patient, wherein the transmitting antenna is housed within the wearable device.
21 . The system of claim 1 , further comprising a transmitter antenna and a receiving antenna configured to form a magnetically coupled resonator (MCR) by matching a resonance frequency between the transmitter resonator and the receiver resonator.
22 . The system of claim 1 , wherein the housing is configured for implantation into a right atrium of the patient, the housing having an inlet and an outlet spaced longitudinally from the inlet, the inlet and the outlet defining a primary blood flow path from a left atrium through at least a portion of the housing to an aorta.
23 . The system of claim 1 , wherein the rotor and the impeller are spaced from the internal surface of the housing and at least partially supported with hydrodynamic forces within the housing.
24 . The pump of claim 1 , wherein the fluid bearing comprises one or more surfaces that create a fluid pressure that resists axial forces generated by the impeller or the rotor.
25 . The pump of claim 1 , wherein the fluid bearing comprises one or more surfaces that create a fluid pressure that resists radial forces generated by the impeller or the rotor.
26 . The pump of claim 1 , wherein the secondary blood flow path is in an opposite direction as the primary blood flow path.
27 . The pump of claim 1 , wherein the second mass flow rate is about 5% to about 10% of the first mass flow rate.