Spinal cord stimulation relieves severe angina

NEW YORK, May 12 (Reuters) Heart-related chest pain or angina is usually treatable with drugs or heart surgery but for people who are not helped by these approaches, spinal cord stimulation may relieve symptoms, German researchers report.

Spinal cord stimulation ''is performed by means of an electrode installed in the epidural space and connected to a neurostimulator typically implanted subcutaneously in the upper left abdominal region,'' the team explains in the May issue of the medical journal Heart.

Dr. Heinz Theres of Charite Hospital, Berlin and colleagues note that there have been no ''blinded'' studies of this approach because patients can feel whether the spinal cord stimulator is on or off.

Unless people cannot tell if they are receiving active or inactive treatment, the results can be compromised by the so-called placebo effect in which expectations lead to perceived benefits.

Spinal cord stimulation at a standard 3 to 5.5 volts induces a prickling sensation. On the other hand, ''subthreshold'' stimulation at 2 to 4 volts - which can't be felt - had not been tested because it was believed to be ineffective.

However, animal studies have shown that stimulation at the lower levels increase blood flow through the skin. So, the researchers studied 12 patients who had already been treated with spinal stimulation for angina and had responded.

They were given four kinds of treatment for 4 weeks at a stretch, in random order. These involved standard spinal cord stimulation for 24 hours per day or for three 2-hour sessions, subthreshold spinal cord stimulation for three 2-hour sessions daily, or a ''control'' phase using just 0.1 volts for 24 hours per day.

''Patients blinded to active spinal cord stimulation show an improvement in functional status and a reduction in angina,'' Theres told Reuters Health.

There were no significant differences between standard and subthreshold treatments in terms of the distance patients could walk without developing angina. However, there was a significant reduction in walking distance during the control phase when the stimulator was essentially inoperative.

The frequency of angina attacks and their severity were also significantly worse in the control phase. In fact, the control phase had to be ended early for three patients because of intolerable angina attacks.

The option to use subthreshold stimulation as an active but patient-blinded treatment facilitates future studies, say the investigators, and may extend its clinical application.

''This study opens a completely new field in spinal cord stimulation research,'' Theres said.

REUTERS GT RK0920