Feasibility, safety and efficacy of the Freedom* Stimulation System for Peripheral subcutaneous field stimulation (PSFS) application in patients with chronic refractory angina pectoris. A Pilot Study

For patients suffering from therapeutic refractory chronic pain spinal cord
stimulation (SCS) has been advocated, most often as a last resort. The same
accounts for patients with chronic angina pectoris, therapeutic refractory to
conventional therapies.
SCS requires meticulous placement of an electrode in the epidural space in the
cervicothoracic region, however, placement is not always technically feasible,
mostly due to a difficult anatomy. Furthermore, electrode placement is time
consuming and associated with all risks of an invasive procedure such as
infection and bleeding. Therefore alternative treatment options with a
comparable neuromodulatory effect need to be explored, in this case placement
of subcutaneous electrodes in the chest region where angina is projected.
Earlier, we demonstrated in an observational pilot study that such a
subcutaneous application of the therapy is feasible and effective. When
compared to the available literature of SCS, both quality of life and exercise
capacity improved significant during follow-up and both outcomes were
comparable with SCS.
However, longer follow-up revealed problems with lead migration and subsequent
loss of effectiveness in a significant number of patients.
With a recently developed electrode, which has a different design and is
approved for refractory chronic spinal pain, we hypothesize that subcutaneous
stimulation is as feasible and effective as the previous systems, but the
procedure is less cumbersome for both the patient and the surgeon and the lead
migration will be much less of a problem.

The primary objective is to determine the efficacy of pain control with this
type of Peripheral Subcutaneous Field Stimulation (PSFS) at three months and 12
months. The secondary objectives determined at both 3 and 12 months are the
assessment of the safety of the procedure, indicated by any intraoperative and
postoperative complications such as bleeding, infection, lead migration and
other technical problems. Furthermore the feasibility of the implantation and
burdens for the patient (such as need for frequent re-programming) will be
assessed. Based on the available literature we expect to find at least 50%
reduction in angina complaints and subsequent use of short acting nitrate
intake

Interventional trial with medical device.

Placemnet of up to three electrodes subcutenously in the ventral part of the
chest where the aptient is usually having angina complaints.

Following the standard care manner of acting, potential candidates for
neuromodulation are referred from the department of cardiology to paincentre of
the department of anesthesiology of the UMCG. Eligible patients will be
referred to the implanting physician for explanation of the procedure and
physical examination. When, after a respite of minimally 2 week , written
informed consent is obtained the patient is referred to the preoperative
assessment clinic. Prior to the procedure the participants are asked to fill in
questionnaires and to undergo standardized bicycle exercise stress testing.
Participants are admitted at the day of the procedure to undergo the procedure
under local anesthesia, under sterile conditions in an operating room. The
decision to continue anticoagulant treatment or not will be done by the
cardiologist in charge, based upon patients* characteristics. In our previous
pilot study with subcutaneous stimulation, in which the implantation procedure
required significant more tissue manipulation, when compared to the present
electrode, no bleeding complications where noted. Thus, we expect no extra risk
for (late) bleeding. Nevertheless, an ultrasound-scan will be performed at the
end of the procedure and the patient will stay overnight for monitoring. The
scan is repeated prior to release from hospital to detect any formation of
hematoma. In the following period, ongoing bleeding or any sign of wound
infection may require surgical revision and antibiotic therapy if indicated. In
case of lead migration and / or ineffective stimulation, removal of the lead is
not necessary, since the lead is not expected to cause long-term problems and
does not interfere with, for instance, MRI, if indicated. However, lead(s) will
be removed at the express whish of the patient. To remove the lead only a small
surgical procedure is required, which usually can be done in an outpatient
setting.
One week after the procedure all participants will return for control of the
surgical wound and possible adaptation of the stimulator settings. In case of
insufficient coverage or unpleasant paresthesia an earlier return to the
hospital might be necessary for re-programming. All patients are asked to
document, in a diary, the number of episodes of angina, use of stimulation and
use of GTN, during the week preceding the follow-up visit at 3 months and 12
months. At the 3 months follow-up visit the bicycle exercise-test will be
repeated