br Case report A year old woman who had been
Case report A 41-year-old woman who had been fitted with a pacemaker for bradycardia 18 years prior presented for lead extraction on account of device infection. She had a left pectoral dual chamber pacemaker, with two tined leads: an atrial lead of 5524 M (Medtronic, Dublin, Ireland) and a ventricular lead of 5024 M (Medtronic), both silicone-insulated (Fig. 1). We performed lead extraction under general anesthesia in the operating room. We deployed an LLD EZ (Spectranetics, Colorado Springs, CO) locking stylet for each lead and attempted to advance a 14-French GlideLight (Spectranetics) laser sheath over the atrial and ventricular leads. However, significant binding in the region between the subclavian vein and the innominate vein precluded the laser sheath advancement. An 11-French TightRail (Spectranetics) rotating mechanical sheath was then deployed to overcome the binding segment. The rotating sheath crunched through the binding tissue and was slowly advanced into the superior vena cava over the ventricular lead, after which progress halted (Fig. 1A). We removed the TightRail from the body and found 1–1.5-cm-long pieces of bone-like calcified tissue lodged in the sheath lumen (Fig. 1B). After removing these ossified tissues, both leads were extracted with the laser sheath, without complications. The photomicrograph showed paucicellular fibrous tissue mainly comprised of eosinophilic material-forming layers (arrow in Fig. 2A). Focal calcification was observed (arrows in Fig. 2B), but no acute thrombus with fibrin or inflammatory kainate receptors was detected. These findings were consistent with the diagnostic symptoms of ossified thrombus.
Discussion Lead extraction using a laser sheath is effective in most cases. However, long implant duration is a predictor of failed laser extraction [1,2]. Although calcification is a well-known barrier to laser extraction, its origin has not been sufficiently studied. In the present case, the barrier to the laser extraction was an ossified thrombus. Encapsulation of the transvenous pacing leads has been reported in canine models , and thrombus organization has been found to give rise to a vascularized collagenous capsule. Under continued blood flow perturbation, more thrombi can form and reorganize, causing the collagenous capsules to grow with the implant time. Under certain conditions, such as inflammation from lead insulation, the encapsulating sheath can mutate and split into cartilage, mineralized tissue, and even bone. In the present case, the severe calcification was overcome with a rotating mechanical sheath rather than with a laser sheath. Although it was not used in this case, a simple mechanical sheath may be less expensive compared to a TightRail sheath and may be effective in overcoming calcification . Although the experience with TightRail has been limited, its efficacy has been reported with positive results, equivalent to those of the laser sheath . A rotating mechanical sheath might allow for transvenous lead extraction in the presence of significant ossification. For a successful procedure, it is mandatory to prepare various types of tools for lead extraction.
Conflict of Interest
Introduction T wave oversensing (TWOS) is a common cause of inappropriate implantable cardioverter-defibrillator (ICD) therapies. Diminution of the R wave amplitude or dynamic gain of the T wave amplitude is a major cause of TWOS . However, it is sometimes difficult to reproduce TWOS [1–3], which makes the management of TWOS by a noninvasive method difficult. A sensitivity change without any evidence often fails to prevent TWOS [1–3]. We experienced two cases of inappropriate ICD therapies due to TWOS, and we were able to reproduce TWOS by body twisting.
Case 1 A 32-year-old man was referred to our hospital for resuscitation from ventricular fibrillation (VF). After several examinations, he was diagnosed as having idiopathic VF. A single chamber ICD was implanted (Gem Model 7227, Medtronic Inc., Minneapolis, MN, USA). An integrated bipolar dual-coil ICD lead (6944, Medtronic Inc.) was used. At implantation, the pacing threshold was 0.3V at 0.5ms; R wave amplitude, 13.8mV; and lead impedance, 1429Ω. Ventricular tachyarrhythmia detections were programmed only in the VF zone above 188bpm. Therapy consisted of only ICD shocks. Sensitivity of the R wave was set at 0.3mV.