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New S-ICD® System Defibrillates Without Touching the Heart
The Parkview Heart Institute, part of Parkview Regional Medical Center in northeast Indiana, recently became the first institution in the state of Indiana to implant Boston Scientific’s S-ICD® System for the prevention of life-threatening ventricular arrhythmias. This is an implantable defibrillation system that avoids vascular access or the use of fluoroscopy. The Heart Institute’s approval to implant status is the result of a long-term research relationship between Parkview and the clinical trial efforts (IDE study, Cameron Health) that preceded the device approval. 
The Parkview Research Center participated in the clinical trial, which tested the effectiveness of the S-ICD® System. FDA approval came in September 2012, after the pre-market study demonstrated the effective identification and correction of cardiac arrhythmias. The S-ICD® System far surpassed acceptable expectations in the Investigational Device Exemption (IDE) clinical study. It was proven to be more reliable in providing appropriate, effective conversion shocks (100 percent conversion of induced ventricular fibrillation) and fewer site complications (patients were 99 percent free of category 1 complications at 180 days post-surgery) than traditional, vascular implants.1
The pursuit of this technology aligns with a continuation of local efforts for early identification of
patients at high risk for sudden cardiac death (SCD) and maximization of appropriate treatment. In 2013 Parkview Research Center presented “The use of Wearable Cardioverter Defibrillator among high risk cardiac patients” as per the ‘Sudden Cardiac Death Primary Prevention Protocols’ developed by a Heart Rhythm Society physician working group. This provides a recommended pathway of action for physicians and support staff on behalf of patients demonstrating a post-acute myocardial infarction ejection fraction (EF) of less than 36 percent. As part of this protocol, a robust program for safely bridging the CMS-mandated waiting period between diagnosis and ICD implantation was developed to include use of the ZOLL LifeVest® wearable defibrillator.
Dr. Mirro was the principal investigator of the S-ICD clinical trial at Parkview. Upon approval by the FDA, Dr. Mirro applied to use the new device for patients receiving treatment at Parkview Heart Institute. After completing their training last December in St. Paul, Minnesota, Dr. Mirro and David Schleinkofer, MD from PPG - Cardiology were the first in the state to implant the S-ICD. Drs. Richard Otten and Bradley Hardin, also with PPG - Cardiology, are set to receive the highly recommended specialized training, and will be implanting the device as well.
The S-ICD® System adds to the list of electrophysiological services provided by the Parkview
Heart Institute and offers new options for patients who may otherwise endure complicated implantation procedures due to compromised vasculature. Subclavian occlusion, mastectomy, or extensive tortuosity make traditional vascular implantation logistically complex and require extended procedure time. Additionally, the S-ICD is a viable option for patients who have had their leads and ICD devices explanted due to persistent infection.
Great effort is now being made to enroll all S-ICD recipients in a two-part, post-market study with Boston Scientific and Cameron Health. The S-ICD Post Approval Study is a non-randomized registry that will retrospectively enroll subjects who participated in the S-ICD Clinical Investigation (IDE G090013) and prospectively enroll new candidates for the S-ICD System.2 The post-market study will last five years and is composed of a screening EKG portion and annual follow-up visits with a research coordinator to have their device checked. Study follow-up can be done in correlation with the Arrhythmia Diagnostic Center at Parkview, which schedules appointments every four
months. Participation in the study enables Parkview to submit data and any device-related injuries or concerns to Boston Scientific. In turn, Boston Scientific shares this information with the FDA for documented long-term safety and effectiveness.
Thus far, Parkview’s S-ICD patient population represents secondary implantation due to infection or lack of vascular access. The process involves explantation of the contaminated intravascular device and leads. The patient is evaluated to determine if a defibrillator with pacing capabilities is required, and the ZOLL LifeVest® is utilized to protect the patient during their time of recovery. When it is determined that pacing is not a requirement of their ICD, potential candidates for the S-ICD® System undergo a multi-positional screening EKG to validate that the configuration of the electrode and generator will create an appropriate vector for successful conversion of the patient-specific arrhythmia, regardless of how their body may be positioned.
Although the current patient population is comprised of secondary implant patients, the IDE study of the S-ICD clearly demonstrated effectiveness in a broad range of patient types, including those
receiving their first ICD implantation. Drs. Mirro and Schleinkofer support the results of the IDE trial and view the S-ICD as an appropriate option for patients receiving primary implants. Patients who may benefit from preservation of venous access include younger patients and patients who participate in rigorous athletic activities. In addition, the relatively small incisions required for the placement of the subcutaneous shocking electrode may be a preferable cosmetic option for some patients hoping to minimize visible scarring.
Education of the entire team is a critical step in ensuring the successful introduction of the S-ICD procedure. Physicians benefit from education regarding appropriate patient types, screening procedures, and implant techniques. EP lab staff members involved in S-ICD procedures need additional training in positioning, prepping, and draping to allow for a successful implantation. Staff involved in pre- and post-op care also needs to be aware of the differences in procedure preparation and post-implant incisional and device care. These educational requirements are straightforward to many. However, additional consideration should be given to educating other departments that commonly correspond with patients who have implanted devices, including the emergency,
diagnostic imaging, and radiation oncology departments. These caregivers are familiar with seeing implanted devices in standard, intravascular positions, and need to be made aware of alternate options. Collaborating across the health system helps to ensure successful outcomes and positive patient experiences.
The implantation procedure involves a single electrode placed subcutaneously in the midsternal region and the S-ICD generator being placed beneath the skin in the mid axillary line over the rib cage, leaving the cardiovascular system completely untouched. Prior to draping the patient for their procedure, careful attention is given to ensuring proper positioning of the device. Anatomical landmarks are used as a reference when guiding the lead along the left side of the sternum, eliminating the need for the use of fluoroscopy or X-ray contrast in 95 percent of all S-ICD implants.3 A pocket is created in the left mid axillary region where the generator is implanted. Both the electrode and generator are sutured into place to prevent migration. Considering anticipated battery life, it can be expected that the generator will need to be replaced approximately every five years.
Repetitive bending can result in a lead fracture, which may interrupt sensing and therapeutic capabilities. Inappropriate or ineffective shock delivery may result. Because this device is implanted subcutaneously, extensive wear on the leads due to the whip-like action caused by a beating heart or the phenomenon known as “clavicular crush” is avoided. To date, there have been no occurrences of fractured electrodes with the S-ICD® System.
When intravascular leads require explantation, due to fracture or infection, the EP staff and CV surgical team work symbiotically in the region’s only electrophysiology hybrid suite. This innovative collaboration allows for the efficient transition from electrophysiology procedure to a surgical intervention should the need arise, therein providing an added level of safety to the patient.
Besides benefiting the patient, the addition of the S-ICD procedure brings value to the hospital. The reduced rate of complications, when compared to intravascular implantation, translates into fewer readmissions and a shorter length of stay. The typical hospital stay may become even shorter, due to there being no leads affixed to the heart. Generally, a device check is performed the next day due to the potential for the leads to alter position or dislodge. Because there is no longer this potential, the check is unnecessary and patients may begin going home the same day. Additionally, anatomical positioning means fluoroscopy is not a requirement of an implant suite. This frees up the fluoro-equipped rooms for other procedures. Also, the predictable and faster implant time aids in scheduling and results in time for additional procedures to be added.
As the single Indiana hospital who participated in the study, the Parkview Heart Institute is the exclusive site in the state where these devices are now available. Use of the S-ICD® System differentiates Parkview from all other hospitals in Indiana.
Disclosure: The authors have no conflicts of interest to report regarding the content herein. Outside the submitted work, Dr. Mirro reports consultancy with ZOLL Medical and grants/grants pending to his institution from St. Jude Medical.
References
- Raul Weiss, Bradley P. Knight, Michael R. Gold, et al. Safety and Efficacy of a Totally Subcutaneous Implantable-Cardioverter Defibrillator. Circulation. 2013;128:944-953, doi:10.1161/CIRCULATIONAHA.113.003042
- S-ICD® System Post Approval Study. ClinicalTrials.gov. Published November 27, 2012. Available online at https://clinicaltrials.gov/ct2/show/NCT01736618?term=s-icd&rank=4. Accessed November 13, 2013.
- Burke M, et al. Safety and Efficacy of a Subcutaneous Implantable-Defibrillator (S-ICD System US IDE Study). Late-Breaking Abstract Session. HRS 2012.
