Contrast medium injected during Micra Pacemaker placement
Figure 1A: Contrast medium injected to further define the region.

The Electrophysiology Program at Penn Medicine offers the Micra Transcatheter Pacing System (Medtronic) for select patients with bradycardia.

The world’s smallest pacemaker, the Micra is a self-contained, leadless, percutaneous, single-chamber ventricular pacemaker delivered through the femoral vein to the heart. Held firmly in the right ventricle, the Micra can remain active for as long as 12 years to provide rate-responsive pacing and automated pacing capture threshold management, as needed.

The Micra is the result of recent advances in miniaturization, novel materials, high-density battery chemistry and bioengineering innovation. Examples of the latter include the placement of electrodes directly on the pacemaker capsule and the use of a superelastic nitinol fixation mechanism to ensure firm and durable implantation.

By avoiding the need for transvenous leads and a subcutaneous “pocket”, the Micra significantly decreases the risk of device-based infection and provides an alternative pacing strategy to patients with limited vascular access.

In safety studies, the Micra was associated with significantly fewer major complications than standard pacemaker devices, a disparity attributed to reduction in access site events (hematoma and infection at the site of implantation), device pacing issues and lead dislodgement. [1]

Case Study

Micra deployed by releasing tines
Fig. 1B: Micra deployed by releasing 4 fine nitinol tines.

Mrs. G, a 69-year-old woman, was referred to Robert Schaller, MD, at the Electrophysiology Program at Penn Medicine for pacemaker consideration due to chronic atrial fibrillation and bradycardia. Mrs. G’s medical history offered several obstacles to traditional transvenous pacing, including hemodialysis-dependent end-stage renal disease and a dialysis fistula on the right side. Moreover, due to a recent systemic MRSA infection on the left side involving a previous pacemaker and requiring extraction of the unit, Mrs. G’s left side was also relatively contraindicated. As a result of limited vascular options and high risk of future device-related infections with a traditional pacemaker, Mrs. G chose to have a Micra implantation.

For the procedure, which took about an hour, Mrs. G was first placed under sedation. Femoral venous access was acquired and the delivery sheath was guided to the heart. The Micra was then steered to the right ventricle under fluoroscopic guidance and placed in an apical septal location.

Post-operative scan of Micra Pacemeker confirms placement
Fig. 1C: A post-operative CXR shows proper device location.

Contrast medium was injected to further define the region (Fig. 1A and video below). With confirmation of an ideal site, the Micra was deployed (Fig 1B) by releasing 4 fine nitinol tines. The electrode at the base and pacing anode at the exposed end of the Micra were then evaluated, followed by fluoroscopic assessment of the tines to ensure fixation.

At this point, the tether was cut and withdrawn and the sheath was removed from the heart. A superficial “figure of eight” suture was deployed at the venotomy site with immediate hemostasis. A post-operative CXR showed proper device location (Figure 1C).

Mrs. G remained in the hospital overnight and after repeat interrogation the following day, discharge planning was initiated. In the ensuing weeks, she experienced no complications. Right ventricular pacing proved ideal in Mrs. G’s case due to her history of chronic atrial fibrillation.

Access

Penn Heart & Vascular Center
Perelman Center for Advanced Medicine
East Pavilion, Second Floor
3400 Civic Center Boulevard
Philadelphia, PA 19104

Use of contrast dye to define placement of Micra Pacemaker in the RV
Published on: February 28, 2017

References

FDA News Release: FDA approves first leadless pacemaker to treat heart rhythm disorders
US Department of Health and Human Services
April 16th, 2016

About Penn Electrophysiology

Penn Medicine has the largest electrophysiology program on the East Coast and one of the largest hospital-based programs in the U.S. Comprised of full-time, board-certified electrophysiologists, specialized nurse practitioners, and physician assistants, the EP team is dedicated exclusively to treating and eliminating serious and potentially life-threatening heart rhythm disturbances. The team’s leadership in ablative and arrhythmia device therapy is evident in their continuing commitment to research and publication.

Penn Faculty Team

Francis E. Marchlinski, MD

Director of Electrophysiology Laboratory, Hospital of the University of Pennsylvania

Director of Electrophysiology, University of Pennsylvania Health System

Richard T. and Angela Clark President's Distinguished Professor

Robert D. Schaller, DO

Assistant Professor of Clinical Medicine

David Lin, MD

Associate Professor of Medicine at the Hospital of the University of Pennsylvania

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