Successful Implantation of Impella 5.5 Device and Subsequent Recovery in a Pediatric Patient with Small Arterial Vessels

Abstract

Introduction The Impella 5.5® with SmartAssist System® has short term use (≤14 days) approval for cardiogenic shock. The largest diameter of the device is the 19 Fr pump motor (∼6.33 mm). We discuss a case of successful implantation, wean and explantation in a child with arterial vessels measuring smaller than the pump motor. Case Report A previously healthy 11 year old male presented with severe systolic dysfunction, ventricular arrhythmias and progression to cardiac arrest. Initial left ventricular ejection fraction (LVEF) was 27%. Femoral veno-arterial ECMO support was initiated. Endomyocardial biopsy was negative for myocarditis. He was transitioned to Impella 5.5® as a bridge to decision/recovery after 4 days of support. Pre-implant ultrasound showed the right subclavian artery measured 4.8 mm x 5.1 mm, smaller than the recommended 7 mm for adult implantation of Impella 5.5®. Despite this the 5.5 was implanted due to increased device longevity versus the smaller Impella CP®. A 10 mm diameter graft was anastomosed to the axillary artery and tunneled with an exit site lateral to the pectoralis major. Gentle pressure and external manipulation of the axillary artery allowed stepwise advancement and placement without complication, despite some resistance at the graft vessel junction. Device performed as expected at 4.5 liters on P8. The patient was extubated POD 4 and placed on oral cardiac remodeling and antiarrhythmic therapies with ongoing nutritional support and cardiac rehabilitation. Complications included access site bleeding, wound dehiscence requiring wound VAC and revised surgical closure. He improved over several weeks and tolerated weaning of support. The device developed low purge flow and high purge pressures, despite TPA per protocol, and was explanted POD 29. Post explant, he completed a 4 week antibiotic course for S. epidermidis bacteremia. He underwent subcutaneous ICD implant for gene-negative long QT syndrome and was discharged 2 months after presentation with an LVEF of 51%. Summary The Impella 5.5 can be used in a child with small arterial vessels and expected recoverable cardiac function, avoiding a sternotomy and ventriculotomy, and allowing for recovery and discharge to home.