The pacemaker, about two inches in diameter and one-fourth inch thick, is encased in a stainless steel frame and is surgically implanted under the skin in the lower abdomen. It carries a lead wire, containing four platinum electrodes, that is threaded to a site within the sacral canal, near the sacral nerves at the base of the spine. These are the nerves that regulate bladder function. Once installed, the device is externally programmed by the physician to send electrical impulses to the nerves. This signals the bladder and pelvic muscles to contract or relax as urine is stored or eliminated.
Patients can also regulate the device, within certain set limits, by turning it up or down.
In clinical trials in the United States, Canada and Europe, the device reduced the number of leaking episodes among 74 percent of the 458 patients within six months after implantation. Almost half of the patients remained completely dry. The most common problems associated with the device were discomfort at the pacemaker site caused by the presence of the device, the movement of the lead wire, infection and skin irritation, the studies found. But all of these were mild and infrequent, the studies found. When the stimulation is on, patients usually report feeling a kind of tugging sensation and may experience a vibration or an electric tingling, but over time they may forget the device is in place, Anderson said.