Implantation of a Subcutaneous Implantable Cardioverter-Defibrillator in an Adolescent

Takumi Yamada, MD,1H. Thomas McElderry, MD,1 and Yung R. Lau, MD2, 1Division of Cardiovascular Disease, and 2Department of Pediatric Cardiology, University of Alabama at Birmingham, Birmingham, Alabama 

Takumi Yamada, MD,1H. Thomas McElderry, MD,1 and Yung R. Lau, MD2, 1Division of Cardiovascular Disease, and 2Department of Pediatric Cardiology, University of Alabama at Birmingham, Birmingham, Alabama 

Case Summary

A 14-year-old male with no significant medical or family history developed a ventricular fibrillation arrest. He was successfully resuscitated by an intravenous administration of epinephrine and multiple external defibrillations, and despite over 90 minutes of resuscitation, has shown no long-term end-organ sequelae. A transthoracic echocardiogram revealed that his left ventricular ejection fraction (EF) was severely reduced to 25% on admission, but completely recovered to a normal EF. He underwent a heart catheterization and full electrophysiology study by a pediatric electrophysiologist. No abnormalities were found except for two out of four biopsy samples showing a nonspecific finding of dense collagen. It was then determined that he needed an implantable cardioverter-defibrillator (ICD) for secondary prevention. He was referred to the electrophysiology service for a subcutaneous ICD placement.

Prior to the procedure, the patient underwent ECG screening to exclude any possibility of  T wave oversensing. After informed consent was obtained, the patient was brought to the electrophysiology laboratory in a fasting state and sedated by general anesthesia. The skin was prepped with a chlorhexidine scrub and draped at the area from the right of the sternal midline to the posterior axillary line in the usual sterile manner. A curved incision was made in the vicinity of the left 5th and 6th intercostal spaces and at the mid-axillary line, and a pocket was created on the fascial plane. Next, an approximately 2 cm long horizontal incision beginning at the xiphoid midline was made for the suture sleeve. A dissection was performed down to the fascial plane. A subcutaneous tunnel from the xiphoid incision toward the pocket along the fascial plane was created with a tunneling tool (Q-GUIDE, Boston Scientific) (Figure 1). The distal tip of the lead (Q-TRAK®, Boston Scientific) was attached to the tunneling tool using a long suture loop, and pulled through the tunnel to the xiphoid incision with the tunneling tool until the proximal sensing electrode was exposed at the xiphoid. The suture sleeve was secured to the lead with a 1 cm separation from the proximal sensing ring (Figure 1). Next, the distance to the presumable superior sternal incision was measured by holding the suture sleeve at the xiphoid incision and laying the electrode along the skin over the left border of the sternum. Because the patient was expected to grow afterwards, the site of this incision was determined by making the lead warp. A 2 cm long superior sternal vertical incision was made, and a subcutaneous tunnel was created from the xiphoid incision toward the superior sternal incision parallel to the sternum with a tunneling tool. Once the tip of the tunneling tool came out of the superior sternal incision, the suture attached to the tip of the lead was cut and retained from the tunneling tool. After the tunneling tool was removed, the electrode was pulled up to the superior incision using the retained suture. Following this, the suture sleeve was sutured to the fascia at the xiphoid incision first, and then the distal tip of the lead was sutured to the fascia at the superior incision. Following this, the lead was connected to the pulse generator (S-ICD System, Boston Scientific). The pulse generator was inserted into the pocket, and anchored with a stitch sutured to the intercostal muscle. The pocket was irrigated with a combination of bacitracin and polymyxin solution, and one deep layer was sutured to close the wound. After the electrogram amplitude and impedance were normally measured, defibrillation testing was performed. The first 65-Joule shock successfully defibrillated the patient. Following this, all incisions were closed with absorbed sutures. The subcutaneous ICD was programmed to have two detection zones with a conditional zone of >200 beats per minute and a shock zone of >220 beats per minute. The post-procedural chest radiogram confirmed an appropriate placement of the S-ICD System (Figure 2). No complications occurred. During more than six months of follow-up, the patient has been free from any ICD shocks.

Discussion

It has been proven that implantable ICDs can improve the survival in patients at high risk for sudden cardiac death.1-4 However, conventional ICDs can often cause complications associated with transvenous leads.5 The acute lead complications include lead dislodgement, pneumothorax, cardiac perforation, pericardial effusion, and cardiac tamponade. Chronic lead complications include systemic infections as well as insulation breaches and conductor coil breaks, which can cause inappropriate shocks and physical trauma to the heart, and may render ICD therapy unavailable. The lead is the most common failure mechanism for a transvenous ICD system, and especially in pediatric patients, they will almost certainly outlive the useful lifespan of the lead.6,7 The long-term complications associated with transvenous ICD leads have been the rationale to develop a totally subcutaneous ICD.5 The S-ICD System received CE Mark in 2009, and the U.S. Food and Drug Administration granted regulatory approval for the S-ICD System in September 2012. To date, more than 2,000 devices have been implanted in patients around the world. The indication of this system has been increasingly recognized.

The S-ICD System is completely subcutaneous, not requiring leads in the heart, and placed strictly by anatomical landmarks. Its sophisticated algorithms have proven to provide effective defibrillation for ventricular tachyarrhythmias equal to transvenous ICDs.5,8 The S-ICD System has several advantages over a transvenous ICD system including no risk of vascular injury, low risk of lead failure with no restriction of arm movement or systemic infection, preservation of a venous access, avoidance of risks associated with endovascular lead extractions, and no requirement of fluoroscopy at the time of the implant. On the other hand, the S-ICD System has several disadvantages compared with a transvenous ICD system. The S-ICD System cannot provide bradycardia pacing, anti-tachycardia pacing for patients with incessant monomorphic ventricular tachycardias (VT), or atrial diagnostics. Therefore, the S-ICD System is intended to provide defibrillation therapy for the treatment of life-threatening ventricular tachyarrhythmias in patients who do not have symptomatic bradycardia, incessant ventricular tachycardia, or spontaneous, frequently recurring VT that is reliably terminated with anti-tachycardia pacing.

This case was one of the typical candidates suitable for a subcutaneous ICD implantation for several reasons. First, the patient was a young, active boy with a high risk for lead failure with a transvenous ICD system. Second, he had a history of a ventricular fibrillation arrest, suggesting no requirement of anti-tachycardia pacing. Third, he had no indication for bradycardia pacing. In this case, the implantation of the S-ICD System could be performed in the same manner as in the adult cases, except for the lead positioning. Because pediatric patients are expected to grow afterwards, the tip of the lead should be fixed at a lower site that allows for a warp in the lead.

Conclusion

A lead failure such as lead fractures or dislodgements can often occur with a transvenous ICD system. An ICD lead failure can lead to a loss of therapy or to inappropriate shocks. In the pediatric population, lead failures with transvenous ICD systems have been more common than in adults, and this is particularly important because pediatric patients are usually very active and use the ICD lead for years. Therefore, the S-ICD System with a low risk of lead failure may benefit the pediatric population. 

Disclosure: The authors have no conflicts of interest to report regarding the article herein. Outside the submitted work, Dr. McElderry reports grants and personal fees from Boston Scientific. 

References

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