Boston, MA - A safety and feasibility study assessing the use of real-time intracardiac echocardiography for the placement of left ventricular pacing leads has shown that their placement can be safely guided by intracardiac ultrasound and that the insertion and optimization of the left ventricular pacing leads resulted in an immediate improvement in echocardiographic dyssynchrony and left ventricular ejection fraction.

Lead study investigator Dr Peter Gallagher (Central Baptist Hospital, Lexington, KY), who presented the early data here at the Heart Rhythm Society 2006 Scientific Session, told heartwire that the nonresponder rate to cardiac resynchronization therapy (CRT) is approximately 33%, ranging from 15% to 45%. One of the reasons that patients might not respond favorably to therapy could be related to inadequate left ventricular lead tip location, and it is hoped that echocardiographic assessment during implantation could result in long-term improved outcomes, he said.

"With biventricular pacing, one of the limitations is that we end up putting the leads into places without really knowing if they're effective," said Gallagher. "You can do tissue Doppler echo prior to the procedure and after procedure, but if you have no improvement after, you've already done the implant. The idea here was, during the procedure, to use intracardiac echo to get real-time assessments of contractility."

In this present study, Gallagher and colleagues report data on 10 patients who underwent intracardiac echo and velocity vector imaging to direct left ventricular lead placement. An intracardiac echo catheter (Acuson, Siemens Inc, Malvern, PA) was advanced to the mid-right ventricular septum through the sheath in the subclavian vein designated for the right atrial lead. Echo data were acquired at baseline and during biventricular pacing, and left ventricular lead placement was based on a visual assessment of the site that best improved systolic contractility, as well as the site associated with the greatest reduction in dyssynchrony.

Positioning of the ultrasound catheter via the left subclavian vein was successful in all 10 patients, with no complications. A postprocedure analysis using velocity vector imaging showed normalization in the regional strain patterns in segments with prior dyssynchrony in six of seven patients. At six months, eight patients had a reduction in NYHA congestive-heart-failure status and six patients had improvements in left ventricular ejection fraction. Of the three patients with no improvements in ejection fraction, two had no dyssynchrony at baseline.

Of the patients who had the final left ventricular lead position determined by real-time echocardiographic findings at the time of implant, Gallagher noted that an anterior lead location was the best position in one patient, while left ventricular pacing alone was better than biventricular pacing in another. One previous nonresponder had a significant improvement after the lead was repositioned.

"It's very rapid, very fast, and provides real-time assessment," said Gallagher. "I think we're going to learn a lot about the physiology of synchronization from this, and I think it's not only going to help reduce the nonresponder rate, but it's probably going to more importantly maximize patients' potential response."