First interventional exchange of a left transvenous phrenic nerve stimulation lead from the novel remede system.

The remede system is a novel fully implantable transvenous phrenic nerve stimulation (TPNS) device developed to treat central sleep apnea. No information is published on how to explant or replace its leads. An eighty-one year-old had a fractured lead and we removed it over a wire. However, unbreachable resistances occurred with a new lead deployed over the enclosed wire and interventional endovascular techniques were performed to reimplant a new fully functioning system. This first report demonstrates TPNS lead exchange is possible but can be challenging. Interventional maneuvers and techniques, including balloon angioplasty, can facilitate this procedure.

How to implant a phrenic nerve stimulator for treatment of central sleep apnea?

BACKGROUND: Central sleep apnea (CSA) is a breathing disorder caused by the intermittent absence of central respiratory drive. Transvenous phrenic nerve stimulation is a new therapeutic option, recently approved by the FDA , for the treatment of CSA. OBJECTIVE: To describe the technique used to implant the transvenous phrenic nerve stimulation system (the remede System, Respicardia, Inc). METHODS: The remede System is placed in the pectoral region, typically on the right side. A single stimulation lead is placed in either the left pericardiophrenic vein (PPV) or the right brachiocephalic vein (RBC). A sensing lead is placed into the azygous vein to detect respiration. RESULTS: In the remede System Pivotal trial, 147 of 151 (97%) patients were successfully implanted with the system. Sixty-two percent of stimulation leads were placed in the PPV and 35% in the RBC. Mean procedure time was 2.7 ± 0.8 hours and 94% of patients were free from implant-related serious adverse events through 6 months. CONCLUSION: In patients with CSA, transvenous phrenic nerve stimulation is an effective and safe therapy with an implant procedure similar to that of cardiac implantable electronic devices.

Suitability of the pericardiophrenic veins for phrenic nerve stimulation: an anatomic study.

OBJECTIVE: The objective of this study was to assess the potential of the pericardiophrenic veins (PPVs) as conduits for transvenous stimulation of the phrenic nerves. Modulating respiration with transvenous phrenic nerve stimulation via the PPVs might reduce or eliminate the adverse effects of central sleep apnea in heart failure. METHODS: Forty-eight fixed cadavers were dissected to study the anatomic characteristics of the PPVs and related neurovascular structures. RESULTS: The right PPV, found in only 1 of 35 cadavers, was <0.5 mm diameter. The left PPV, located in all 48 cadavers, drained into the left brachiocephalic vein (BCV) directly or into the BCV via the superior intercostal vein (SICV). Mean ± SD SICV trunk diameter was 4 ± 2 mm. Mean ± SD left PPV diameter was 2 ± 1 mm. The length between the point of separation of the left PPV from the phrenic nerve to its junction with the BCV or SICV trunk ranged from 6 to 40 mm. The angle of approach, defined as the angle formed by the intersection of the longitudinal axis of the BCV and the longitudinal axis of the PPV or SICV trunk, and which represents the angle that would need to be navigated when inserting a stimulation lead into the PPV using a peripheral cannulation approach, was 99 ± 28 degrees. Valves were identified in 54% of left PPVs. CONCLUSIONS: Because of its extremely small size, the right PPV appears unsuitable for transvenous phrenic nerve stimulation. In contrast, the left PPV may be accessible via the left BCV using standard transvenous catheterization techniques; however, the small caliber of the left PPV and the frequent presence of valves within it might pose challenges in navigating the vessel to achieve transvenous phrenic nerve stimulation.

Phrenic nerve stimulation in patients with central sleep apnea: a single­center experience from pilot and pivotal trials evaluating the remede System.

BACKGROUND: Patients with central sleep apnea (CSA) have recently been shown to have improved sleep metrics and quality of life (QoL) with phrenic nerve stimulation (PNS). AIMS: The aim of this study was to report the results of a partnership between cardiology, sleep medicine, and electrophysiology in a single clinical center as well as the enrollment, implantation, and follow­up experience demonstrating both the safety and efficacy of PNS. METHODS: This analysis included data from the pilot and pivotal trials investigating the effect of PNS using an implantable transvenous system in patients with CSA. We present our experience and data on the enrollment processes, implantation feasibility and safety, sleep indices, and QoL at 6 and 12 months of follow­up. RESULTS: Between June 2010 and May 2015, cardiology patients were prescreened and 588 of them were sent for in­home sleep test. Ninety­six patients were referred for polysomnographic studies, and 33 were enrolled and had an implant attempt, with 31 successfully receiving an implant. The apnea-hypopnea index was reduced in the pilot trial (mean [SD] of 48.7 [15.5] events/h to 22.5 [13.2] events/h; P <0.001) and in the pivotal trial (mean [SD] of 48.3 [18.8] events/h to 26.0 [21.9] events/h; P <0.001). Improvement in QoL was also observed. CONCLUSIONS: We showed that PNS improved sleep metrics and QoL in patients with CSA, which is a result of multiple factors, including a comprehensive coordination between cardiology, sleep medicine, and electrophysiology. This ensures appropriate patient identification leading to safe implantation and full patient compliance during follow­up visits.

Improved extraction of ePTFE and medical adhesive modified defibrillation leads from the coronary sinus and great cardiac vein.

BACKGROUND: Permanent leads with shocking coils for defibrillation therapy are sometimes implanted in the coronary sinus (CS) and great cardiac vein (GCV). These shocking coils, as documented by pathologic examination of animal investigations, often become tightly encapsulated by fibrosis and can be very difficult to remove. METHODS: One of three configurations of the Guidant model 7109 Perimeter coronary sinus shocking lead was implanted into the distal portion of the GCV of 24 sheep for up to 14 months. Group 1 had unmodified coils (control), group 2 had coils backfilled with medical adhesive (MA), and Group 3 had coils coated with expanded polytetrafluoroethylene (ePTFE). Eighteen leads, three from each group at 6 and 14 months were transvenously extracted from the left jugular vein. The remaining six animals were not subject to extraction. All animals were euthanized for pathological and microscopic examination. RESULTS: All six of the control, three of the MA, and one of the ePTFE leads required the use of an electrosurgical dissection sheath (EDS) for extraction. Five control, two MA, and none of the ePTFE leads had significant fibrotic attachments to the shocking coils. Significant trauma was observed at necropsy for those leads requiring the use of the EDS for extraction. CONCLUSIONS: Tissue ingrowth is a major impediment to the removal of defibrillation leads implanted in the CS and GCV of sheep. Reduction of tissue ingrowth by coating the shocking coils with ePTFE or by backfilling with MA facilitates transvenous lead removal with reduced tissue trauma.