Manipulation of an implanted transvenous pacemaker by the patient, causing entanglement of the leads and malfunction of the device was first described, as far as we are aware, in 1968.1 It became known as “Twiddler's syndrome” and has subsequently been documented as an unusual cause of malfunction of pacemakers in adults,2 and also reported in adults with internal cardioverter-defibrillators.3, 4 The manipulation may occur consciously or unconsciously, and classically involves rotation of the device on its long axis within the pocket. Another variant of the problem, the Reel syndrome, has also been described and occurs when the device is flipped on its transverse axis, causing the leads to coil around the generator itself.5 Both self-inflicted problems may result in displacement of the pacemaking leads, with resultant loss of myocardial capture and unintentional stimulation of the chest wall musculature, the diaphragm, the liver, or other structures.6, 7 Herein, we describe our experience with a child who inadvertently moved his pulse generator, causing itto malfunction, and leading to acute syncope, hospitalization, and the need to explant the device, re-implanting it in the abdomen in the hope of minimizing further self-inflicted manipulation.
Case report
A 7-year-old boy with a right-sided heart, isomerism of the right atrial appendages, and complex functionally univentricular physiology, underwent palliation by establishment of the Fontan circulation. He then required replacement of his atrioventricular valve with a St. Jude prosthesis in 2001, this procedure being complicated by surgically induced complete heart block. He subsequently required implantation of a single chamber ventricular pacing system using a sew-on epicardial lead and a St. Jude Affinity 5130 generator, programmed in VVIR mode. A new epicardial lead was placed one year later, after the thresholds increased on the original lead, which was left capped off in the pocket. The generator was replaced in June, 2004, with a St. Jude Verity 5156 when the old generator electively required replacement, but the lead was not replaced (Fig. 1a). He did well at home for several months, until he presented in mid-January of 2005 after two syncopal episodes at school, the second of which occurred while sitting at his desk in class, causing him to fall and hit his head on the floor. He was hospitalized, during which time he experienced several other documented episodes of ventricular non-capture, requiring adjustment of the output from the pacemaker (Fig. 2). Interrogation of his generator demonstrated inconsistent capture, even at a maximum output of 7.5 volts and 1.5 milliseconds. A chest X-ray showed severe entanglement of both previously placed epicardial leads, albeit without fracture of the leads. In addition, there was complete inversion of the apex of the generator (Fig. 1b). At the time of admission, he consistently denied any manipulation of the device, and his parents had not witnessed any such actions. Upon further questioning, he admitted to his parents that he would often roll the device around in its pocket out of habit, more often when he was nervous. He was taken to the operating room, where both ventricular leads were found to be disconnected from the heart. The leads and the device were removed, and replaced with new leads and a new generator placed in an abdominal position with creation of a pocket in the right upper quadrant deep to the rectus muscle (Fig. 1c). The postoperative course was uneventful, and he has done well since replacement of the device, without further episodes of syncope, and no evidence of “twiddling” either by radiography or observation.
Figure 1. (a) Baseline chest X-ray, showing normally-placed epicardial leads and the device positioned within the chest. (b) X-ray taken after the malfunction, showing knotted epicardial leads and inversion of the device on its long-axis. (c) Re-implantation of a new generator in an abdominal position, along with new screw-in leads and explantation of the previous displaced generator and knotted leads.
Figure 2. A 21 second episode ventricular non-capture. Episodes of non-capture could be precipitated by turning this patient left side up, which removed the pacemaker leads from the connection with the epicardial surface.
Discussion
The prevalence of implanted pacemakers in children, while much smaller than in adults, has been steadily increasing. This increase in prevalence of insertion of devices has occurred for a variety of reasons, including an increase in surgical procedures for correction of congenital cardiac malformations in childhood, improved long-term survival, changing indications for implantation, and the availability of smaller devices. Malfunction of the devices in children may not result from the same causes, nor be treated in the same manner, as in adults. In our case, the malfunction occurred because the child repetitively and habitually manipulated his device, resulting in dislodgement of the leads, complete heart block, and symptoms.
Children are more likely than adults to experience lifestyle-related malfunction of their pacemaker or leads as a result of usually higher levels of activity, different types of activities, and the need for the leads to last longer. In addition, children are usually thinner and smaller than adults, factors that may leave the device relatively more exposed and easily palpated under the skin, thus making it more amenable to conscious or unconscious manipulation. This, coupled with innate curiosity about changes in their bodies and lower behavioral inhibitions, may produce situations such as the one we have described. With this in mind, several techniques could be considered to help avoid malfunction due to self-manipulation. Placement of the generator in the abdomen is common for younger or smaller children, but perhaps should be employed for older children prone to fidgetiness or nervous habits. Abdominal placement may also shield the device from some unintentional sports or “rough and tumble” damage. In addition, smaller pockets, and placement of greater numbers of subcutaneous retention sutures, may prevent intentional as well as innocent dislodgement. Overall, Twiddler's syndrome remains a rare cause of pacemaker malfunction, even in children. Its prevalence, nonetheless, may increase in concert with the number of pacemakers implanted in children. Familiarity with Twiddler's syndrome has obvious implications for surgical implantation, and may help clinicians avoid this potentially dangerous complication.
Acknowledgements
We thank Andrew Atz and J. Philip Saul for their assistance with, and comments on, this manuscript.
