Lead-Based Masses: An Iatrogenic Challenge No One Saw Coming!
Cardiac implantable electronic devices (CIEDs) have undergone tremendous changes over the years. Since the days of Hyman, they have undergone transformation from backups in emergencies to dependable workmen. In keeping with the same transformation, an entirely new treatment modality (cardiac resynchronization devices) emerged. Expected challenges of implanting devices in the body, namely, infection, fracture, generator replacements have all occurred and managed with varying levels of success. However one unexpected challenge slipped under the radar, the presence of lead based masses (LBM).
Very great care has always been taken to exclude the presence of foreign material within the left side of the heart. If there has been need to do so, care to ensure adequate anticoagulation has always been taken. However the right side is a different story. Leads have been placed within the right side of the heart since their very conception with the thought that significant clot burden may not exist or even if it does, the resultant pulmonary emboli may not cause significant clinical challenges to face. The risk benefit ratio was considered to be skewed in favor of avoiding anticoagulation.
However, recent studies have shown an increase in the incidence of stroke in patients with CIEDs associated with patent foramen ovale (PFO). Use of intracardiac echo for electrophysiological procedures has also brought to our notice, the size of these masses. Commonly present on the atrial side of device leads, these masses are benign on their own, but given the vagaries of the patency of the interatrial septum, they can assume a more sinister nature.
From a proceduralists point of view, this is challenging since transseptal punctures become a high-risk procedure loaded with the challenge of a possible stroke contraindicating performance of pulmonary vein isolation. Ablation for ventricular tachycardia may still be performed using a retroaortic route., However in older individuals, traversing the aortic arch with a catheter may still be fraught with the risk of dislodging a calcific plaque. Lead extractions are also a challenging proposition, given the possibility of snow ploughing into the laser sheath or a massive pulmonary embolism with a large LBM.
Good solutions to this problem does not exist at this point. The nature of these masses is currently unknown. The contribution of fibrous tissue versus the contribution of thrombi to these masses is debatable. Anticoagulation or an increased intensity of the same to a target INR of 2.5-3.5 is currently the proposed solution. Role of newer anticoagulation agents (NOACs) in the management of these LBM is also not known.
A solution to this unforeseen problem is currently pending. Given the extensive use of CIEDs all over and the increasing lifetimes of this generation, this has the potential to become a serious issue. Absence of a specific protocol for NOAC use prior to a procedure, management of LBMs if high intensity anticoagulation fails, continued coexistence of LBMs and PFOs in healthy population, incidence of subclinical strokes in these patients are all questions that merit serious consideration. A potential way of side stepping the problem is the use of newer technology like leadless pacemakers and subcutaneous defibrillators. But this technology is still evolving in addition to work bench technologies like photosensitive ionic channels and biological pacemakers. In the absence of reliable alternatives, LBMs are a problem we stare at in the present, without an immediate solution.
Deepak Padmanabhan, MD
Clinical Cardiac Electrophysiology Fellow, Mayo Clinic, Rochester, MN
Deepak Padmanabhan is an Electrophysiology fellow at Mayo Clinic , Rochester, MN. His research deals with ventricular arrhythmias, cardiac device therapy and translational medicine. His opinions are solely his own. Follow him on Twitter @manak_18.