Implanted bladder pacemaker restores control of urinary function
BY RUTHANN RICHTER
Just as a cardiac pacemaker helps maintain a steady heartbeat, a new bladder pacemaker helps men and women with debilitating bladder problems regain control of this vital function, according to urologists at Stanford and UCSF who pioneered the technology.
The implantable bladder pacemaker delivers a painless electrical stimulus to the nerve fibers that regulate the muscle of the bladder. This enables patients to control urine storage and release, said Dr. Emil Tanagho, a UCSF professor of urology whose early work with paraplegics and quadriplegics led to the development of the device.
Tanagho and Dr. Rodney Anderson, a Stanford professor of urology, are among the three physicians in California and the only two in Northern California are currently implanting the device, which was approved by the FDA in September 1997.
The new pacemaker may benefit patients suffering from urge incontinence, the inability to control the strong, sudden urge to urinate. It could also help people with severe bladder problems associated with multiple sclerosis, Parkinson's disease, interstitial cystitis or pelvic pain produced by overactive pelvic muscles.
People who lack bladder control can be virtually incapacitated by their condition, making multiple daily trips to the restroom and suffering the embarrassment and discomfort of frequent bladder leakage. The bladder pacemaker "is a major breakthrough in the management of many patients with severe voiding problems that can interfere with their well-being. It can restore their freedom and give them back normal function," Tanagho said. "For these patients it's a major change in lifestyle as well as productivity. It's a quality-of-life issue, and the difference is day and night."
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, 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.
The device is a much-needed addition to the medical arsenal, Anderson said, because in the past physicians have had few options to offer patients with severe bladder control problems. Some medications can help regulate bladder function, but they don't work for all patients and can have unpleasant side-effects, he noted. Some patients may undergo a surgical procedure known as bladder augmentation, but it is a major operation that has mixed results, he said.
"We just have very weak tools to combat this kind of problem, so this [device] is a welcome addition," Anderson said.
Patients go through a preliminary, three-to-seven-day period of testing before the bladder pacemaker can be installed. This involves use of a test stimulator, resembling a pager, that the patient can wear on a belt. The stimulator is attached to a pacer electrode that is placed through the skin of the patient's lower back, where it generates an electrical pulse to the sacral nerves.
About half the time, the test stimulator is found to help relieve patients' symptoms and restore bladder control, Anderson said. These individuals then can be fitted with the implantable device. For patients, installation is a relatively simple surgical procedure that takes 1 1/2 to two hours, he said.
Although few physicians currently have experience in installing the new device, Tanagho said he expects the pacemaker to gain wider availability over time as more urologists receive the specialized training required for its implantation and use.
The original concept for the device grew out of Tanagho's research in the 1970s on methods for managing the bladder in patients with spinal cord injuries. Duke University researchers had proposed a method of implanting an electrode in the spinal cord for this purpose, but Tanagho found that this approach could damage the cells in the spinal cord that control urination.
With support from the National Institutes of Health, he began exploring the idea of implanting electrodes into the nerve bundles in the sacral root, conducting clinical trials in the 1980s on paraplegic and quadriplegic patients. In the process, he said, he found that neurostimulation also could be helpful to much less severely injured patients who nonetheless had difficulties with bladder control. "We found we could rehabilitate them and restore normal bladder function," he said.
In the late 1980s, Tanagho directed
clinical trials on the first-generation bladder pacemaker,
recruiting Anderson to participate. UCSF now holds the patent on
the technology, which is licensed to the Minneapolis-based
Medtronic Inc. The company manufactures the device under the trade
name Interstim. SR