Wireless vascular monitoring implants

1. A wireless vascular monitoring implant adapted to be deployed in a patient vasculature, positioned at a monitoring location in a vascular lumen and implanted in contact with the lumen wall, said implant comprising a resilient sensor construct configured to dimensionally expand and contract with natural movement of the lumen wall, wherein:

said resilient sensor construct comprises a coil forming a variable inductance resonant circuit configured and dimensioned to extend circumferentially around the inside of the vascular lumen in engagement with the lumen wall when implanted within the lumen;

said resilient sensor construct is configured to move with expansion and contraction of the lumen wall;

the inductance of the resilient sensor construct changes in a known relationship to the dimensional expansion and contraction of the lumen wall;

when energized, said resilient sensor construct produces a wireless signal indicative of said inductance, said signal being readable wirelessly outside the vascular lumen to determine a dimension of the vascular lumen;

the resilient sensor construct further comprises a frame;

said coil is formed of multiple strands of conductive wire wrapped on the frame; and

said frame consisting of a single cylindrical loop of thin, resilient metal having a sinusoidal shape or structure of repeating “Z” shapes so as to collapse into a delivery sheath to expand upon deployment from said delivery sheath into the vascular lumen.

2. A wireless implant sensor system, comprising:

a resilient sensor construct comprising a coil configured and dimensioned to be implanted in a patient vascular lumen in contact with the lumen wall around the inner circumference of the lumen wall and to dimensionally expand and contract with natural movement of the lumen wall, wherein an electrical property of said resilient sensor construct changes in a known relationship to dimensional expansion and contraction thereof; and

an antenna positionable external to the patient's body configured to receive a wireless signal from said resilient sensor construct indicative of said electrical property to enable determination of a dimension of the vascular lumen; and

wherein:

said coil of the resilient sensor construct has a variable inductance correlated to its dimensional expansion and contraction along at least one dimension of the vascular lumen; and

said resilient sensor construct produces, when energized by an energy source, a signal indicative of inductance in said resilient sensor construct readable wirelessly outside the patient's body such that a dimension of the vascular lumen may be determined therefrom;

said coil comprises a resonant circuit having said variable inductance and a fixed capacitance to define a resonant frequency, wherein the resonant frequency varies based on changes in shape of said coil, said signal readable outside the patient's body being correlated with said resonant frequency;

said coil is configured to be energized by a magnetic field directed at the coil from outside the patient's body; and

said resilient sensor construct further comprises a resilient metal frame consisting of a single cylindrical loop, and said coil comprises multiple strands of conductive wire wrapped with at least one turn around the single cylindrical loop of the resilient metal frame.

3. A wireless vascular monitoring implant and sensor system, comprising:

a sensor construct adapted to be deployed in a patient vena cava, positioned at a monitoring location in the vena cava, and implanted in contact with the vena cava wall, said sensor construct being configured to dimensionally expand and contract with natural movement of the vena cava wall, wherein

said sensor construct is configured and dimensioned to extend circumferentially around the inside of the vena cava wall in engagement therewith when implanted within said lumen;

an electrical property of the resilient sensor construct changes in a known relationship to the dimensional expansion and contraction of the vena cava, and

when energized, said resilient sensor construct produces a wireless signal indicative of said electrical property, said signal being readable wirelessly outside said vascular lumen to determine a dimension of the vena cava lumen;

a delivery catheter configured to receive and hold the resilient sensor construct in a compressed state for insertion through the patient's vasculature to the monitoring location in the vena cava, said resilient sensor construct configured to expand to engage the vena cava wall upon release from the delivery catheter; and

an antenna positionable external to the patient's body configured to receive said wireless signal from said resilient sensor construct indicative of said electrical property to enable determination of the dimension of the vena cava lumen;

wherein the sensor construct comprises:

an expandable and collapsible cylindrical loop frame consisting of a single cylindrical loop;

at least one conductive wire disposed around said frame to form said coil with adjacent substantially parallel wire strands along the frame, said coil forming a variable inductor of a resonant circuit wherein the resonant circuit has a resonant frequency that varies based on changes in shape of said coil; and

said coil produces frequency signal representative of the shape of said coil when energized by a magnetic field directed at the coil.

4. The wireless implant and sensor system of claim 3 , wherein the cylindrical loop frame and at least one conductive wire are configured and dimensioned in combination to cause the resonant circuit to change characteristic frequency with natural expansion and contraction of the vena cava in response to changes in patient fluid volume state.