ECGs and Pacemakers Advancements in Pacemaker …

1 2017 American Association of Critical-Care Nurses doi: and PacemakersLeadless Pacemakers will most likely be the future of cardiac pacing. Leadless pacing employs a single-chamber system to pace only the right ventricle and is fully self-contained, which eliminates the need for leads. These systems, implanted by using a transcatheter sheath, are indicated for patients who need right ventricular pacing only. These devices enable patients to avoid lead-related complications, from lead fracture to extraction challenges, as well as pocket-related complications such as infection and disfigure-ment. Leadless Pacemakers also are compatible with magnetic resonance imaging and do not require surgical placement, so patients avoid postoperative mobility restrictions. Because this technology will be increasingly used for cardiac internal electronic devices, commonly seen in critical care nursing, nurses must be knowledgeable about the indications for use of a wireless Pacemaker , the implantation pro-cedure, postprocedural care, device interrogation, and follow-up.

2 This article discusses leadless pacemak-ers, clinical indications for their use, key similarities and differences between the current devices being used, key points for nursing care of patients with a leadless device, and the future of this technology. (Critical Care Nurse. 2017; 37[2]:58-65)Mary Leier, MScN, FNP-BCAdvancements in Pacemaker Technology: The Leadless DeviceLeadless Pacemakers may represent the future of cardiac pacing. This article describes how leadless pacing works, indications and contraindications for its use, and the key differences and similarities between 2 different leadless pacing devices. The Micra, made by Medtronic, is currently available and has been approved by the US Food and Drug Administration (FDA) for use in the United States. The Nanostim, made by St Jude Medical, is still under research and is not yet commercially available in the United States. Key points for nursing care of patients with a leadless Pacemaker , and the future possibilities of the leadless system, some of which are currently in the research/development phase, also are article has been designated for CE contact hour(s).

3 The evaluation demonstrates your knowledge of the following objectives:1. Identify the indications for a leadless pacemaker2. Describe the implantation procedure for the leadless system and how it differs from the traditional single chamber Pacemaker system implantation procedure3. List the main benefits of the leadless system when compared to the traditional single chamber Pacemaker deviceTo complete evaluation for CE contact hour(s) for test #C1722, visit and click the CE Articles button. No CE test fee for AACN members. This test expires on April 1, American Association of Critical-Care Nurses is an accredited provider of continuing nursing education by the American Nurses Credentialing Center s Commission on Accreditation. AACN has been approved as a provider of continuing education in nursing by the State Boards of Registered Nursing of California (#01036) and Louisiana (#LSBN12).

4 CE hour, CERP A58 CriticalCareNurse Vol 37, No. 2, APRIL 2017 CriticalCareNurse Vol 37, No. 2, APRIL 2017 59 What Is Leadless Pacing?Leadless pacing employs a single-chamber system, pacing only the right ventricle, and is fully self-contained, which eliminates the need for leads. Traditional cardiac Pacemakers consist of a pulse generator, containing the battery and the circuitry for sensing and timing of elec-trical impulses, and the leads, insulated wires that deliver electrical impulses from the pulse generator to the heart muscle. Pacemakers may be single or dual chambered: single-chamber Pacemakers have 1 lead that carries impulses to either the right atrium or the right ventricle. A dual-chamber Pacemaker usually has 1 lead to the right atrium and 1 lead to the right ventricle to allow synchro-nous atrioventricular (AV) pacing. Traditional Pacemakers require a surgical incision in the chest to create a subcutaneous pocket for the pulse generator.

5 Complications that arise from placement of the pulse generator in the chest pocket include hematoma, infection, and skin breakdown or erosion. Additionally, the implanted generator can cause reduced shoulder mobility and chronic pain. Removing the lead compo-nent of the pacing system allows the patient to avoid lead-related complications such as fractures, insulation breaches, venous thrombus obstructions, and leads crossing the tricuspid valve, which can induce tricuspid regurgitation. For these reasons, the lead component has always been the weak link in traditional pacing sys-tems. Leadless Pacemakers are ideal for patients who have had prior infection related to a cardiovascular implant-able electronic device and patients who have venous access issues. Further problems arise when leads must be extracted to treat infection or valve regurgitation, as lead removal can be associated with complications such as traumatic injury of the heart or the superior vena cava, which can cause fatal internal Leadless Pacemakers Are ImplantedImplantation of a leadless Pacemaker takes a total of 30 to 40 minutes.

6 The device is implanted through a single access site in a femoral vein, using an 18F intro-ducer sheath for the Nanostim or a 23F introducer sheath for the Micra. A delivery catheter is fed from the access site up through the inferior vena cava, into the right atrium, passing down through the tricuspid valve, with implantation directed toward the septal aspect of the apex of the right ventricle. All patients require pre-medication with heparin to prevent formation of blood clots during the implantation procedure. Contrast media also may be used to visualize catheter advancement through the fem-oral vein and the location of the delivery system during the implantation procedure. One of the main differences between the 2 competi-tors devices lies in the details of the fixation method. Medtronic s Micra uses a linear 1-step deployment of 4 tines that are attached to the device (Figure 1), allow-ing the device to be anchored in the right ventricle and enabling direct interaction between the electrode and The tines deploy away from the electrode-to-tissue connection, which allows any development of fibrosis to occur away from the point of contact, which helps to stabilize pacing thresholds.

7 St Jude s Nanostim uses a helix fixation method, a corkscrew fixation to the right ventricle, requiring torque force to deploy, similar to a traditional lead (Figure 2). Both devices AuthorMary Leier is a nurse practitioner for the Electrophysiology and Heart Rhythm Center at Cedars Sinai Heart Institute, Cedars-Sinai Medical Center, Los Angeles, author: Mary Leier, MScN, FNP-BC, Electrophysiology and Heart Rhythm Center, Cedars Sinai Medical Center, 127 S San Vicente Blvd, Suite 3600A, Los Angeles, CA 90048 (e-mail: purchase electronic or print reprints, contact the American Association of Critical-Care Nurses, 101 Columbia, Aliso Viejo, CA 92656. Phone, (800) 899-1712 or (949) 362-2050 (ext 532); fax, (949) 362-2049; e-mail, 1 Medtronic s Micra leadless Pacemaker . Reproduced with permission of Medtronic pacing uses a single-chamber system, pacing only the right ventricle, and is fully self-contained, eliminating the need for CriticalCareNurse Vol 37, No.)

8 2, APRIL 2017 an estimated battery life of 10 to 12 ,2 Each device has a single dose of mg of dexamethasone acetate covering the fixation mechanism and electrode to prevent tissue final placement of the leadless unit is achieved and the device is released, pacing begins. Both devices have a rate-response mechanism, a temperature sensor within the Nanostim and an accelerometer in the Micra, that can adjust to pace the patient on the basis of the patient s activity level. The delivery catheter is removed, and a single-suture closure is placed at the access site. Same-day discharge is possible. The venous access implantation site has no bump, no scar, and there are no activity restrictions after implantation, unlike in patients receiving a traditional Pacemaker . Use of a leadless Pacemaker also eliminates the possibility of pocket-related complications such as infections, hema-toma, and ,2 In the short term, both devices could be removed if necessary by using a snare-type technique; however, the device becomes encapsulated by cardiac tissue over time, and by the battery s end-of-life, a new device would be placed near the existing one.

9 Both leadless systems have an off switch that allows upgrading in response to treatment needs or discontinuation of pacing if no longer ,2 Indications for Leadless PacingThe leadless Pacemaker is indicated for patients with a class I or II indication for pacing based on guidelines: atrial fibrillation with complete AV block or bradycardia, after AV nodal ablation and pacing for atrial fibrillation, intermittent sinus arrest, or procedural AV block with the possibility of conduction recovery (after valve replace-ment), or symptomatic paroxysmal or permanent high-grade AV block with no atrial fibrillation, as an alternative to dual-chamber pacing when atrial lead placement is considered difficult, high risk, or not necessary for effec-tive therapy (see Table).1,2 Contraindications for Leadless PacingBecause the leadless system is approved for ven-tricular pacing only, the devices are contraindicated in patients with pure sinus node dysfunction, patients with an implanted inferior vena cava filter or a mechani-cal tricuspid valve, and patients with an implanted cardiac device providing other cardiac therapy that may interfere with the sensing performance of the Pacemaker (see Table).

10 St Jude lists preexisting pulmonary arterial hypertension or significant physiologically impairing lung disease as contraindications. Other contraindica-tions for both devices include abnormal femoral venous anatomy, inability of a patient to accommodate an 18F to 23F introducer sheath, obstruction or severe tortuos-ity making it difficult to implant a device on the right side of the heart, and morbid obesity that prevents telemetry communication from the device. The leadless system is also contraindicated for patients with a known intolerance to heparin, sensitivity to contrast media, or who cannot tolerate a single dose of to mg of dexamethasone ,2 Performance: Micra by MedtronicThe Micra device is 93% smaller than current tradi-tional Pacemaker systems, 30% smaller than the Nanos-tim, takes up less than 1% of the volume of the right ventricle, is approximately 1 in ( cm) long, and weighs only g (Figure 1).