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Department of Medicine, Saint Louis University Hospital, St. Louis, MoDivision of Cardiovascular Diseases, Saint Louis University Hospital, St. Louis, Mo
Requests for reprints should be addressed to Philip L. Mar, MD, PharmD, Associate Program Director, Internal Medicine Residency, Division of Cardiology, Department of Medicine, Saint Louis University School of Medicine, 1008 S. Spring Avenue, Suite 2113, St. Louis, MO, 63110.
Department of Medicine, Saint Louis University Hospital, St. Louis, MoDivision of Cardiovascular Diseases, Saint Louis University Hospital, St. Louis, Mo
A 54-year-old female with a history of nonischemic cardiomyopathy presented to the outpatient cardiology clinic with intermittent chest pain and “chest thumping.” She had a single-chamber implantable cardioverter defibrillator (ICD) implanted 4 weeks previously.
Assessment
On physical examination, the patient's blood pressure was mildly low at 90/62 and heart rate was 90 beats per minute, similar to vital signs obtained during recent visits. However, the abdominal examination was notable for intermittent diaphragmatic contractions that occurred at a rate of 40 per minute. The ICD incision site on the upper left side of her chest had healed well, and she did not exhibit any signs of volume overload. The rest of her physical examination was unremarkable.
Her ICD was interrogated and demonstrated abnormal lead impedance, absence of lead sensing, and inability to capture the myocardium, all of which were new compared to device interrogation at the time of implantation.
Diagnosis
This patient's history, physical examination, and ICD interrogation were concerning for lead dislodgement. This was confirmed with a chest radiograph (Figure 1). Figure 2 was obtained following her initial ICD placement and depicts a single-lead ICD with the lead tip terminating in the right ventricle (appropriate position). Figure 1 demonstrates that the lead had been retracted to the level of the superior vena cava (SVC) due to “spooling” of the lead around the device generator consistent with Twiddler syndrome. The thumping sensation that the patient was experiencing was due to right phrenic nerve stimulation from the displaced ICD lead causing diaphragmatic contractions at a rate of 40 per minute, which was the lower rate limit of pacing programmed for the device. Phrenic capture following biventricular ICD implantation is rather common because the left phrenic nerve frequently courses near the coronary sinus lead.
In contrast, phrenic capture following single-chamber ICD is exceedingly rare but not impossible as illustrated in this case.
Figure 1Chest radiograph demonstrates distal tip of the lead at the level of the superior vena cava (red arrow) with lead looping around the device (yellow arrows).
Figure 2Original chest radiograph obtained after initial lead placement with tip terminating in the right ventricle (red arrow). Only one loop of lead is present here within the device pocket (yellow arrows).
The patient underwent lead revision with additional device anchoring. Figure 3 demonstrates proper lead placement in the right ventricle following the revision.
Figure 3Chest radiograph obtained after lead revision with distal tip repositioned in the right ventricle.
Twiddler syndrome, sometimes called Reel syndrome, is a catch-all term to include any clinical presentation due to an implanted medical device that includes wiring of some sort coiling around itself and causing unintended effects. First described in 1968 as a complication of pacemaker implantation, the term Twiddler syndrome has come to include all implanted medical devices such as ICD, pacemakers, deep brain stimulators, and spinal nerve stimulators.
As the pacer lead coils around the pulse generator, the distal tip of the pacing lead will migrate proximally toward the generator. Thus, the presentation is highly variable and dependent on the location of the displaced lead tip. Often, the presentation can be silent and diagnosed on routine interrogation.
Based on the presenting radiographic film (Figure 1) the patient's chest thumping was due to diaphragmatic contractions from right phrenic nerve stimulation because the right phrenic nerve is easily stimulated from within the SVC. This presentation has been previously described.
Other presentations include ipsilateral arm myoclonus, pectoralis muscle contractions, abdominal pulsations, unexplained syncope, and inappropriate shocks.
Diagnosis is based on history, physical examination, and chest radiographs. A chest plain film will reveal a proximally displaced lead and characteristic coiling of the wire around the pulse generator. This classic radiographic sign, similar to fishing line winding around the spool, gives the alternate name of Reel syndrome. Old age is a risk factor for developing Twiddler syndrome as the subcutaneous tissue surrounding the pocket are less likely to develop firm adhesions.
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