New strategies eliminate cardiac device transvenous leads

BOSTON – New ways for implanted cardiac rhythm devices to work without need for transvenous leads are in clinical testing, reflecting a keen interest in getting leads out of the vascular space and potentially cutting risks for infections, pneumothorax, hematoma, and the possible need for future lead extraction.

Leads are “the Achilles heel” of pacemakers and defibrillators; “there are too many places where the wire can break,” John D. Day, MD, said in an interview during the annual scientific sessions of the Heart Rhythm Society. Eliminating transvenous leads, or any type of lead for that matter, “solves a lot of problems” that currently occur with implanted cardiac devices, said Dr. Day, a cardiac electrophysiologist with Intermountain Health in Murray, Utah.

Researchers presented results from initial clinical studies with two different alternatives to conventional device leads at the meeting.

The Acute Extravascular Defibrillation, Pacing, and Electrogram (ASD2) study tested a substernal lead in 79 patients enrolled at multiple centers in the United States and elsewhere. The lead’s design uses a minimally invasive subxiphoid approach with substernal lead advancement using a blunt tunneling rod, explained Lucas V.A. Boersma, MD, a professor of cardiology at the Academic Medical Center University in Amsterdam. Placed between the sternum and heart, the lead sits just beside the ventricles to provide both ventricular pacing and defibrillation, unlike existing subcutaneously placed leads that do not allow pacing and require high energy for defibrillation. It took a median of 12 minutes to place the lead, Dr. Boersma said.

Testing demonstrated successful ventricular pacing capture in 76 of 78 patients (97%) who underwent this testing, he reported. A single 30-joule shock delivered via the substernal lead resulted in successful defibrillation of induced fibrillation in 102 of 123 fibrillation events (83%). Six patients had seven adverse events that resolved without sequelae for all but two events. The two events with greater clinical impact included one patient with asystolic cardiac arrest 36 hours after lead placement who developed decompensated heart failure and required medical management, and one patient with pericardial effusion and tamponade who required supportive care.

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The results showed the feasibility of a substernal lead, Dr. Boersma concluded. “There is a learning curve” for placing the lead, he noted. “The subdural space where you place the lead is empty, but you have to be careful to stay within the subdural space,” in a procedure that relies on fluoroscopic guidance.

“We are very used to working in the transvenous space” for lead placement, “and leaving that space is outside the comfort zone” for many clinicians, Dr. Boersma noted. “It will take time to adopt these new technologies, and obviously we need more proof” of efficacy and safety.