Pacing Lead as a High Frequency Cardiomechanic Sensor. Introduction: The purpose of this study was to investigate the possibility of detecting and quantifying ventricular contraction in sheep utilizing the cardiomechanic sensor based upon the high frequency (HF) parameters measurements on bipolar cardiac pacing leads. Measurement of the HF reflection coefficient yields the lead-bending signal (LBS) caused by myocardial contraction. The correlation between the lead-bending acceleration (LBA) expressed as the rate of rise of LBS and LV dP/dt should reveal that LBS may be utilized as a cardiomechanic sensor in implantable cardiac electrotherapy devices.
Methods and Results: We implanted 3 different pacing leads and tested the measurement system in 9 sheep (42 ± 6 kg) at baseline and during acute hemodynamic intervention with dobutamine infusion and tachycardia induced by VVI pacing at 200 bpm. A stable, consistent, and reproducible LBS was obtained in all sheep during the implantation procedure and 4 months after the implantation during different experimental conditions that included hemodynamic interventions. The dependence between LBAmax and LV dP/dtmax was found to be statistically significant and with high Pearson's correlation coefficient (r = 0.855, P <0.001). We could also observe the hemodynamic deterioration caused by fast ventricular pacing with the decrease of LV dp/dt and LBA compared with sinus rhythm.
Conclusion: This study confirms the feasibility and efficacy of the hemodynamic sensor based upon HF lead parameters. Moreover, it was demonstrated that LBAmax is highly correlated to the ventricular contractility and, therefore, can be efficiently used as a hemodynamic and cardiomechanic sensor. (J Cardiovasc Electrophysiol, Vol. 24, pp. 338-346, March 2013)