The U.S. Food and Drug Administration has cleared a minimally invasive pacemaker-implant system from Medtronic that attaches to the inside of the heart in a way that some physicians believe is more healthy for patients long-term.
The new device enables a therapy called “His bundle pacing,” which is intended to prevent some patients from developing “pacemaker-induced cardiomyopathy.” Some patients who get traditional “apical” pacing in the right ventricle may eventually develop this form of pacemaker-caused heart failure, past studies have found.
On Wednesday, Medtronic announced FDA clearance for its SelectSite C304-HIS catheter system. The catheter is used to implant the already-cleared Model 3830 pacemaker lead near a natural nerve structure in the heart called the His bundle (which is named in honor of Swiss cardiologist Wilhelm His, Jr.)
To produce a healthy heart beat, the heart relies on precisely timed electrical pulses in the left and right ventricles. Normally, pacemaker leads deliver current near the bottom (or “apex”) of the right ventricle, forcing the electricity to pass through heart tissue before it can stimulate the left side. This creates a delay that can elongate the heart beat and force the left ventricle to work extra hard to compensate, leading to a weakening of the ventricle over time.
HIS bundle pacing delivers electricity higher in the heart, so that the electric pulses from an implanted device can travel along the natural conduction pathways in the heart, triggering more natural timing in the left ventricle.
Successful His-bundle pacing can theoretically be used to avoid a more complicated implant device called a CRT-P, or cardiac resynchronization therapy pacemaker. His bundle pacing can also avoid having a lead traverse the tricuspid valve, because the bundle is above the ventricle, up in the atrium.
There are drawbacks. It’s more difficult for electrophysiologists to implant the pacemaker lead over the His bundle, requiring the doctor to steer a wire inside the heart in a new way. One recent study found that only 80 percent of His bundle pacing attempts succeeded. Pacing at the His bundle may also require more energy than traditional pacing, and more time in the operating room.
"Pacing at the bundle of His is a promising procedure with a growing body of clinical evidence," said Dr. Pugazhendhi Vijayaraman, electrophysiology director at Geisinger Heart Institute in Pennsylvania, and a paid speaker for Medtronic. "The C304-HIS catheter's adjustable curve design should help implanters reach the His bundle fibers more easily and accommodate a variety of patient anatomies."