engleski

Cardiac lead as a myocardial contraction sensor - animal study

Whenever a high frequency (HF) signal is applied to the cardiac lead, it must be considered a transmission line. Cardiac contractions bend the lead body and extend and compress the lead conductors and their insulation, thereby modulating the HF parameters of the lead. Magnitude of the lead body deflection depends on the radial lead stiffness and on the cardiac muscle contraction forces. The purpose of this pilot study was to investigate the possibility to measure ventricular contraction parameters utilizing the HF parameters measurement on endovenous pacemaker and defibrillator leads . We did HF measurements after implanting ventricular pacemaker and defibrillator leads in nine adult sheep. Network analyzer 3577B (HP, USA) was used in combination with 35676B Reflection/Transmission test kit. We connected IS-1 bipolar connector via sterile coaxial cable to the test kit port. Full calibration procedure of the HF connecting system was done before measurements utilizing measurement signal at different frequencies in the range from 1 to 200 MHz. ECG, EGM from PSA of Medtronic 2090 programmer and HF signal were simultaneously recorded utilizing digital signal acquisition system. Recording was done in 3 different models of ventricular leads. We were able to record the HF reflection signal modulation, caused by the ventricular lead bending, in all nine sheep. The wave obtained by HF measurements system occurred always after the QRS complex during expected ventricular contraction period. Further investigation will include chronic measurements in same nine sheep after 4 months. In the future, we should also determine the feasibility of recording HF reflection signal caused by atrial lead bending, the fidelity of atrial and LV leads signals, and the correlation of HF signal parameters with hemodynamic parameters (dP/dt). The recognition of the hemodynamic stability of arrhythmia and optimization of heart failure therapy including CRT should be investigated utilizing our sensor. The major advantage of our system is that every standard bipolar cardiac lead may be the cardiac contraction sensor without any special device mounted on its body. Additional HF hardware in cardiac devices would be neither design challenge nor source of decreased battery longevity.

hemodynamic sensor; transmission line; cardiac lead

doi: 10.1093/europace/eur231