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:

1. 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.
2. LV lead impedograms vary significantly depending on LV lead location.
3. There are several characteristics of LV lead impedograms that correlate with mechanical phenomena of the heart.

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