Abstract 3161: Longitudinal Validation of Remote Measurements Obtained from an Implanted Intracardiac Pressure Sensor in a Chronic Canine Model
Objective: Longitudinal monitoring of intracardiac pressures (ICP) could facilitate goal-directed management of chronic HF and other cardiac conditions. A recently developed application-specific integrated circuit (ASIC) embedded in a single minute implantable, silicone encapsulated, digitized microchip (0.6cm x 0.2cm x 0.25cm) provides a method for remote telemetric measurements of ICP on demand. In a chronically instrumented conscious dog model, pressure measurements obtained with the sensor implanted in the left atrium (LA) were compared to values acquired directly from a standard fluid-filled catheter/transducer over a period of eight days.
Methods: In an IUCAC-approved protocol, a common dog was chronically instrumented with a zero referenced catheter placed in the left atrium and with an ASIC sensor chip inserted through the wall of the LA appendage. After several days of acclimation, simultaneous (direct and remote) measurements of LA pressure were recorded by the two methods periodically over 8 days. Hemodynamics were manipulated pharmacologically with graded doses of isoproterenol (0.05 to 0.25 ug/kg/min) and a titrated dose of β-blocker. Comparison data were analyzed using a standard Pearson’s correlation.
Results: A total of 52 simultaneous measurements of LA pressure were recorded over the 8-day period. LA pressures ranged from 0.2 to 9.3 mmHg as the heart rate varied from 49–189 bpm and the MAP extended from 59–133 mmHg. Pearson’s correlation coefficient (r) of 0.9 was obtained for the complete compared LA pressure datasets. The correlation of these pressures for days 5 through 8 was improved over that obtained from measurements during days 1 to 4 (0.89 vs 0.72 respectively).
Conclusions: An ASIC sensor digitized microchip implanted in a chronic dog model was found to be longitudinally accurate for remote and on demand telemetric measurement of LA pressures over an eight day period and through a wide range of hemodynamic variations. Furthermore, the measurements were found to be consistently accurate during the entire experimental period. Development of a chronically embedded intracardiac device using this single chip technology could provide a means for continual remote monitoring of important pathophysiologic target pressures.