Author + information
- Received May 20, 2019
- Revision received July 29, 2019
- Accepted August 4, 2019
- Published online October 16, 2019.
- aDepartment of Medicine, Dayanand Medical College and Hospital, Ludhiana, Punjab, India
- bDepartment of Cardiology, Mayo Clinic, Phoenix, Arizona
- ↵∗Address for correspondence:
Dr. Vatsal Ladia, Mayo Clinic, Department of Cardiology, 5777 East Mayo Boulevard, Phoenix, Arizona 85054.
Lead fracture is one of the mechanical complications of implanted cardiac devices. We present a case of mechanical stress-induced left ventricular lead fracture attributed to the hypermobility of the device secondary to sub-muscular implantation of the device without anchoring it. (Level of Difficulty: Intermediate.)
An 85-year-old Caucasian woman moved to Arizona and established follow-up care at Mayo Clinic in 2013. She had a Boston Scientific Cognis cardiac resynchronization therapy with defibrillator (Boston Scientific, Marlborough, Massachusetts) with Guidant 4135 atrial lead, Guidant 0184 right ventricular/defibrillator lead, and Guidant 4518 left ventricular (LV) lead (Guidant, Indianapolis, Indiana). Throughout her quarterly device follow-ups from September 2013 to May 2018, her device parameters remained stable. In May 2018, the patient started to notice a progressive deterioration of her functional capacity and progressive shortness of breath. Her weight at the time of presentation was 48 kg, and body mass index was 19.6 kg/m2. This had reduced by 5 kg since 2013. On physical examination, it was observed that the device under the pectoralis muscle would slide and protrude in the axilla during abduction (Figure 1, Video 1). Venous collaterals were observed on the left side of the chest, suggesting possible stenosis of the left subclavian vein due to prior vascular access. The rest of the physical examination was benign. Her medications included aspirin, carvedilol, sacubitril-valsartan, simvastatin, and spironolactone.
• To be able to identify loss of synchronization therapy.
• To be able to understand factors causing lead fracture.
Past medical history
The patient’s past medical history included: 1) nonischemic dilated cardiomyopathy status post–biventricular implantable cardiac defibrillator (June 2010) with improved ejection fraction (EF) from 19% to 45%; and 2) hypertension.
Differential diagnosis included: 1) decompensated congestive heart failure; 2) loss of biventricular pacing; and 3) arrhythmias.
A repeat echocardiogram showed her EF reduced to 35%. An electrocardiogram (ECG) was performed on the day of presentation showed left bundle branch block (Figure 2). The presentation was ordered, which revealed that her LV lead impedance reading was >2,500 Ω and loss of capture by the LV lead in any of the possible configurations (Figure 3). A chest x-ray was ordered, and on close evaluation, the fracture was evidenced and the LV lead revision was scheduled (Figure 4).
As the patient never had any ventricular tachycardia during the previous 8 years and due to her age, an informed decision was made to downgrade the device to cardiac resynchronization therapy with pacemaker to reduce the size of the device. The old device was explanted from the submuscular pocket, and the coil leads along with old LV lead were capped. A venogram was performed, noting moderate stenosis at the entry site of previous leads; we performed sequential dilations over a 0.018-inch guidewire with 4-F, 6-F, and 9-F before inserting the sheath. Owing to the presence of collaterals, the patient did not develop any swelling of her left arm. A new quadripolar LV lead was placed in posterolateral branch of the coronary sinus and the new device was replanted subcutaneously and anchored to the muscle (Figure 5). An ECG was performed, which showed biventricular pacing, as suggested by right bundle branch block, short PR interval, and negative initial forces in leads I, aVL, V5, and V6 (Figure 6).
The use of implantable cardiac devices as a nonpharmacological treatment alternative for various heart conditions has increased dramatically in the past decade. The United States had the largest number of cardiac pacemaker implants (225,567) (1). Among many complications of an implanted cardiac device, lead fracture of 1 or more leads is not uncommon. Lead fracture, along with the lead dislodgment and perforation, constitute the mechanical or nonfunctional complications of implanted cardiac devices. There are various mechanisms such as a compression of the lead between the clavicle and the first rib, entrapment of the lead by soft tissue in the costoclavicular space, trauma, weightlifting, and aggressive upper limb movement (2–4).
Lead fracture most commonly occurs at the entrance of the lead in the thoracic cavity. It can occur as the result of compression between clavicle and first rib or soft tissue and costoclavicular ligaments. Flexibility of the lead, which permits bending with a short radius of curvature, exerts high stress on metal components and causes lead conductor fracture. Some older studies have suggested that the incidence of lead fracture in pacemaker devices to be 1% to 4% (2,3). The incidence of lead fracture is difficult to estimate due to reporting bias, as the fractured leads are not explanted and returned to the Food and Drug Administration. A multicenter study, with short follow-up of 18.0 ± 16.7 months, reported conductor fracture in 0.18% of the patients studied (5). A longitudinal study followed up all patients receiving Medtronic, Boston Scientific, or St. Jude Medical transvenous implantable cardiac defibrillator leads at the hospitals of the University of Pittsburgh Medical Center from 2000 to 2012, and after accounting for some of the leads that were recalled by the Food and Drug Administration, the incidence of conductor fracture came out to be 0.28% to 1.14% (6). A lead fracture will present with increased impedance of >1,400 Ω with intermittent failure to sense and capture. A chest x-ray and detailed evaluation of the image can easily identify the location. An ECG and device check should be performed to identify failure to capture and sense. Submuscular or subpectoral approach for device implantation was first introduced as a solution to a common complication associated with subcutaneous implantation, which compromises skin circulation by overstretching just above a buried device that is relatively large in size. Apart from affecting the cosmetic appearance, a compromised blood supply to the skin may also lead to ischemic necrosis.
Two weeks after the procedure, the patient reported significant improvement in functional status and her shortness of breath on exertion improved considerably. Echocardiogram performed 5 months after the procedure documented increase in EF to 42%, along with restored functional status to baseline.
The present case report highlights the drawback of submuscular implantation, especially if the device is not anchored to the muscle and allows movement of the device with pectoral muscles. Pectoral muscles are large and powerful; movements of these muscles can displace the device with activity. The strain on the lead conductor due to repeated outward movement of the device with arm abduction ultimately led to the lead fracture. In this case, relatively thicker right atrial and ventricular leads were not affected; however, the thin LV lead was affected. It is important to evaluate device motion and conduct a device site examination in every patient to determine the cause of lead fracture. This case report emphasizes importance of diagnosing loss of resynchronization, identifying the cause of lead fracture and the importance of anchoring the device to the floor of the pocket to prevent extraordinary motion.
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Abbreviations and Acronyms
- ejection fraction
- left ventricular
- Received May 20, 2019.
- Revision received July 29, 2019.
- Accepted August 4, 2019.
- 2019 The Authors