JonGames
Macro Shot Without Backlighting of CardioMEMS 3D Parallel View
This 3D stereographic photo is of the CardioMEMS device, an implantable pressure sensor that wirelessly measures pulmonary artery pressures without requiring any batteries. It is used for heart failure patients to monitor their hemodynamics and estimate their volume status. This aids in prophylactically adjusting diuretics and heart failure medications before a patient becomes symptomatic and has to present to a hospital for a heart failure exacerbation. Reducing hospitalizations and HF exacerbations would aim to reduce mortality and improve quality of life.
The device is pretty amazing as it is very small and works indefinitely without batteries. The main component is a 15mm x 3.4mm x 2mm rectangle with two nitinol wire loops on each side that extend the length of the device to 4.5cm. Nitinol is a metal alloy of nickel & titanium that exhibits shape memory and superelasticity. Nitinol is commonly used for stents and other medical devices as it is biocompatible and folds up nicely in a tiny catheter before being deployed in the body where it expands to its full size and shape. This anchors the device in the distal pulmonary artery.
Its theory of operation is exceedingly simple in terms of design. It consists of a three dimensional coil of wire and two metal plates on two wafers of fused silica encased in silicone. The coil is produced through electrodeposition of gold onto a silica wafer in a vacuum chamber. Fusion bonding is used to join the silica wafers. The coil of wire forms an inductor and the two metal plates act as a capacitor in physics & electronics terms. This arrangement connected in a parallel loop forms a resonant LC circuit (L=inductance, C=capacitance). Depending on the capacitance and inductance of the components, the circuit will oscillate at a perferred resonant frequency. The capacitor in the CardioMEMS is exposed and very thin allowing the silica crystal and metal plates to deform with changes in pressure from the blood within the pulmonary artery. Changing the distance between metal plates of a capacitor changes its capacitance value thereby changing the devices resonant frequency. An external machine can ping and excite the coil with various electromagnetic radio frequencies until it is able to find its resonant frequency. By working backwards, the measured frequency can be converted into an estimated capacitance which can be correlated to an estimated pressure measurement.
The device is placed during the right heart catheterization (RHC) procedure when the physician threads catheters from a patient's veins through the right atria, past the tricuspid valve, through the right ventricle, and finally past the pulmonary valve into the pulmonary artery. Fluoroscopy or video x-rays along with radiopaque contrast are used to visualize the blood vessels and guide the catheters to their destination. During the RHC, the cardiologist will use a Swan-Ganz catheter to measure the actual pressure and calibrate the device's measured pressures to actual pressures.
doi.org/10.1177/1753944719826826
This photo is in 3D parallel view. More Instructions for viewing 3D images: www.3dphoto.net/text/viewing/technique.html
Stereo Viewer for all my photos: jongames.com/stereophoto/
Macro Shot Without Backlighting of CardioMEMS 3D Parallel View
This 3D stereographic photo is of the CardioMEMS device, an implantable pressure sensor that wirelessly measures pulmonary artery pressures without requiring any batteries. It is used for heart failure patients to monitor their hemodynamics and estimate their volume status. This aids in prophylactically adjusting diuretics and heart failure medications before a patient becomes symptomatic and has to present to a hospital for a heart failure exacerbation. Reducing hospitalizations and HF exacerbations would aim to reduce mortality and improve quality of life.
The device is pretty amazing as it is very small and works indefinitely without batteries. The main component is a 15mm x 3.4mm x 2mm rectangle with two nitinol wire loops on each side that extend the length of the device to 4.5cm. Nitinol is a metal alloy of nickel & titanium that exhibits shape memory and superelasticity. Nitinol is commonly used for stents and other medical devices as it is biocompatible and folds up nicely in a tiny catheter before being deployed in the body where it expands to its full size and shape. This anchors the device in the distal pulmonary artery.
Its theory of operation is exceedingly simple in terms of design. It consists of a three dimensional coil of wire and two metal plates on two wafers of fused silica encased in silicone. The coil is produced through electrodeposition of gold onto a silica wafer in a vacuum chamber. Fusion bonding is used to join the silica wafers. The coil of wire forms an inductor and the two metal plates act as a capacitor in physics & electronics terms. This arrangement connected in a parallel loop forms a resonant LC circuit (L=inductance, C=capacitance). Depending on the capacitance and inductance of the components, the circuit will oscillate at a perferred resonant frequency. The capacitor in the CardioMEMS is exposed and very thin allowing the silica crystal and metal plates to deform with changes in pressure from the blood within the pulmonary artery. Changing the distance between metal plates of a capacitor changes its capacitance value thereby changing the devices resonant frequency. An external machine can ping and excite the coil with various electromagnetic radio frequencies until it is able to find its resonant frequency. By working backwards, the measured frequency can be converted into an estimated capacitance which can be correlated to an estimated pressure measurement.
The device is placed during the right heart catheterization (RHC) procedure when the physician threads catheters from a patient's veins through the right atria, past the tricuspid valve, through the right ventricle, and finally past the pulmonary valve into the pulmonary artery. Fluoroscopy or video x-rays along with radiopaque contrast are used to visualize the blood vessels and guide the catheters to their destination. During the RHC, the cardiologist will use a Swan-Ganz catheter to measure the actual pressure and calibrate the device's measured pressures to actual pressures.
doi.org/10.1177/1753944719826826
This photo is in 3D parallel view. More Instructions for viewing 3D images: www.3dphoto.net/text/viewing/technique.html
Stereo Viewer for all my photos: jongames.com/stereophoto/