Abstract 3184: Transmuscular Lead Placement - A new option for biventricular (BiV) pacing
Background: Studies have demonstrated BiV pacing improves outcomes in selected patients with congestive heart failure. Left ventricular (LV) pacing via the coronary sinus (CS) is limited by the location of tributaries and results in epicardial LV activation. Recent studies have suggested that LV endocardial pacing produces better resynchronization. We hypothesized that transvenous delivery of a transmuscular LV septal (LVS) pacing system is feasible, safe, and results in superior cardiac function when compared to traditional pacing configurations.
Methods: Hemodynamic effects of conventional CS pacing and transmuscular LV pacing were compared in anesthetized dogs with normal heart function (n=6). All animals underwent radiofrequency catheter ablation of the atrioventricular junction. A transseptal sheath was introduced into the right internal jugular vein and advanced to the midportion of the interventricular septum. Using a Brockenbrough needle, the sheath was introduced into the LV cavity and a guidewire advanced into the aorta. The transmuscular lead was a 4Fr unipolar LV lead modified with a fixation helix immediately proximal to the electrode. This was advanced over the wire into the LV and then pulled back into the LV endocardium and fixed in position. LV pressure measurements (Millar) were performed to obtain dP/dT in various pacing modes.
Results: All LVS leads were positioned successfully without complications and with adequate pacing thresholds (mean 0.69V@0.5ms). After four weeks of pacing, pathologic examination showed complete endothelization of the LVS electrode. Pacing either LVS or CS resulted in higher dP/dT max (2068±196 and 1982±223mmHg/sec respectively) than did RV apical pacing alone (1785±146mmHg/sec p<.05). BiV pacing using RV-LVS was comparable to RV-CS pacing (2181±246 vs 2036±248mmHg/sec, p=ns) and superior to RV apical pacing (p<.05).
Conclusions: RV-LVS pacing using a transmuscular lead is feasible and results in hemodynamic benefits comparable to RV-CS pacing. Further studies are needed to determine if this is a safe and effective option for BiV pacing.