An Implantable Wireless System for Remote Hemodynamic Monitoring of Heart Failure Patients

Area of Science:

• Biomedical Engineering
• Medical Devices
• Implantable Sensors

Background:

• Remote hemodynamic monitoring is crucial for managing cardiovascular diseases.
• Existing methods often lack continuous, simultaneous measurement capabilities.
• Minimally invasive, implantable solutions are needed for long-term patient management.

Purpose of the Study:

• To develop and characterize an implantable wireless system for continuous, simultaneous monitoring of pulmonary arterial pressure (PAP) and artery cross-sectional area (CSA).
• To evaluate the system's performance in terms of resolution, energy efficiency, and data transfer capabilities.

Main Methods:

• An implantable device integrating a piezoresistive pressure sensor, ASIC, piezoelectric ultrasound transducer, and nitinol anchoring loop was designed.
• Energy-efficient techniques including duty-cycling and spinning excitation were employed for pressure monitoring.
• Artery diameter was measured using the inductive properties of the anchoring loop.
• Wireless power and data transfer were achieved using a single piezoelectric transducer with ASK modulation.

Main Results:

• The system achieved 0.44 mmHg pressure resolution and 0.24 mm diameter resolution.
• It demonstrated high energy efficiency with 1.1 nJ conversion energy for pressure monitoring.
• Ultrasound link efficiency was 1.8% with uplink data rates up to 50 kbps.
• Accurate detection of pressure peaks in an in-vitro arterial flow model was confirmed.

Conclusions:

• The developed implantable wireless system offers a promising solution for continuous, remote hemodynamic monitoring.
• The system provides high-resolution, simultaneous measurements of PAP and artery CSA.
• Its performance in emulated physiological conditions suggests potential for clinical applications in cardiovascular disease management.