Lead embedded pressure sensor

Abstract

A pressure capsule embedded in a pacemaker lead to monitor intracardiac chamber pressure is described. This pressure monitor capsule provides highly accurate pressure readings while insuring a high integrity seal against bodily fluids and tissue growth. The capsule is intended to be embedded into a pacemaker cardiac lead or a catheter with the distal (Tip) isolation diaphragm sensing pressure, coupling the pressure through an air column to a protected sensing MEMS device and providing a secure fluid seal to the lead walls. The proximal (Back) end of the capsule provides the electrical interface through the lead to the pacemaker pulse generator.

Description

FIELD OF THE INVENTION [0001] This invention relates generally to intracardiac chamber pressure sensing and more particularly to pacemaker lead embedded pressure sensing mechanisms. BACKGROUND OF THE INVENTION [0002] Intracardiac blood pressure sensing for research, diagnostic and treatment dates back to the early part of the 20th century, where early investigations utilized a canula or needle-based system with a mercury manometer. Using these techniques, pressure fluctuations in all 4 chambers of the heart have been successfully monitored. Critical diagnostic measurements of right heart systolic (pumping) and diastolic (resting) pressures can indicate disease conditions such as mitrial valve stenosis (stiffening), pulmonary artery hypertension, right heart weakness following myocardial infarction (heart attack), peripheral venus return failure (reduced preload) and electrical anomalies (arrhythmia or conduction). [0003] Blood pressure can be also monitored through a fluid-filled tu...

AI Technical Summary

Benefits of technology

"The present invention provides a small and biologically inert pressure sensing module that can be implanted in a pacemaker lead or catheter. The module has a high signal amplitude and long-term stability, and is capable of chronic low power operation. The module includes a pressure sensing capsule with an electrical circuit and a cavity for transferring pressure to a MEMS pressure sensor. The module can be used to measure pressure in the body, providing valuable information for medical applications such as blood flow monitoring and pressure control."

Problems solved by technology

In contrast, sensors based on a Wheatstone bridge topology require high power levels and are typically too large for implantation.

In addition, the sensors typically need to send the signals back to a remote device to capture the measured signals, often subject to signal degradation in the transmission process.

Thus, the capacitance change per unit pressure is limited by the macroscopic motion of the plate.

However, reduced plate thickness complicates the diaphragm attachment method regardless of whether the diaphragm is welded, or adhesively bonded.

This complicates the decoding electronics for pressure measurement.

Thus, this design is susceptible to capative changes based on the sensing media with which it comes in contact.

Further, thermal effects, mechanical instability and aging effects contribute to an inaccuracy in the measurement taken by the capacitive-based sensor.

For example, as the sensor ages, small movement in the wiring position or compression of the insulation may significantly alter the interconnect capacitance.

The range, accuracy and the repeatability of pressure measurement are not only limited by the motion of the diaphragm and the capacitance of the wiring, but also any thermally induced error.

Since the diaphragm dimension can change by expansion and contraction due to thermal effects, accuracy is limited.

The current state of the art in intracardiac sensing is limited by the low level of signal output, remote sensing requirement, large physical size or custom fabrication for all designs.

Most of the current state of the art sensors such as canula based, fluid filled catheters are not suitable for chronic (long term) unattended implantation.

Others, such as the optical based sensors, require power levels too high for long term battery operation.

These type of sensors may also be prone to long term drifting or lack of sensitivity.

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