Gastric Pacemaker: looking for others who have cared for patients with 'em

Hi,
I work in cardiac care and on occasion, get folks with a gastric pacemaker. Since I do not get them frequently enough, I did not want to generalize my opinion based on the few patients I've had with them.

My question: how effective are they? My pt's with them seem riddled with constipation, pain, and plenty of nausea. Is it just my stroke of luck? They don't seem to work entirely well. I would think that they would eliminate these problems. I thought I'd ask you GI nurses to get your experience on them. Thanks in advance.