Optimal Coronary Sinus Lead Implantation Using Intracardiac Impedography and Magnetic Resonance Imaging

Optimal Coronary Sinus Lead Implantation Using Intracardiac Impedography and Magnetic Resonance Imaging

Real-Time Intracardiac Impedograms of Left Ventricular Leads to Locate Sites of Latest Mechanical Delay in Cardiac Resynchronization Therapy

Despite the dramatic effect of cardiac resynchronization therapy (CRT) on survival and morbidity in people with congestive heart failure, 50-70% of eligible patients do not respond to this intervention. There is retrospective evidence that placement of the left ventricular (LV) lead at the region of latest mechanical delay markedly improves response to CRT. However, there is no feasible way to gauge dyssynchrony at LV lead sites during CRT implantation. Impedance recordings from pacing lead tips allow for real-time assessment of mechanical motion and may represent a useful intraoperative tool to guide optimum placement of the LV lead during CRT implantation. This pilot trial will assess the use of intraoperative impedograms in humans to measure regional dyssynchrony at potential LV lead locations during CRT implantation.

This is a clinical trial using intracardiac impedance signals (impedograms) to assess regional dyssynchrony at various sites of left ventricular (LV) lead placement in humans undergoing CRT device implantation. This study will test the following hypotheses during the funding period: LV lead impedograms as an implant tool to place leads at sites of latest mechanical delay are feasible and correlate with other means of assessing dyssynchrony. LV lead impedograms vary significantly depending on LV lead location. There are several characteristics of LV lead impedograms that correlate with mechanical phenomena of the heart.

Patients with NYHA Class III or IV heart failure; EF ≤ 30% and QRS duration ≥ 120 ms, who are scheduled for CRT surgery. Intervention: Cardiac Resynchronization Therapy (CRT) implantation

The impedance measurement is performed during device implantation following CMR. After the RV and LV leads are inserted, secured and tested, they will be connected to the impedance monitor. Impedance recording of at least ten beats will be acquired and stored for future analysis. Each recording will be tagged with the anatomical location of the LV lead. Subsequently, the LV lead will be moved to a different location and the same procedure will be repeated until accessible coronary sinus sites are exhausted. The ultimate LV lead location is determined by the implanting electrophysiologist and is not constrained by the study protocol. Finally, the LV lead will be tested again and the rest of the implantation procedure will proceed as routine. Arm: CRT Candidate

Anatomic correlation between largest Ts (see description) and site of longest delay among probed locations in the CMR dyssynchrony map.

Parameter will be recorded for at least 10 consecutive heartbeats during sinus and RV paced rhythm Ts = The average time from the sensed RV IEGM to the peak of the LV impedance curve

Ts: The average time from the sensed RV IEGM to the peak of the LV impedance curve. Tp: The average time from the paced RV IEGM to the peak of the LV impedance curve. Td: The difference between Ts and Tp (Tp - Ts).

Inclusion Criteria: Patients with NYHA class III or IV heart failure LVEF ≤ 30% QRS duration ≥ 120 ms Exclusion Criteria: Not a candidate for CRT implantation

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