Sudden Cardiac Arrest (SCA) is a life-threatening heart condition and one of the most common causes of death in developed countries. It claims more than 350,000 lives per annum in Europe1 and about 95% of people who have SCA die before they reach the hospital. Ventricular Fibrillation is the major cause of SCA and the only effective treatment for it is to prompt electrical defibrillation. There are currently two different implantable technologies to prevent SCAs: 1) Transvenous Implantable Cardioverter-Defibrillators (TV-ICDs), which are implanted under the skin with leads that snake through veins into the heart and are attached to the heart ventricles or atria; and 2) Subcutaneous Implantable Cardioverter-Defibrillators (S-ICD), which also have generators and leads but avoiding leads within the heart, being implanted subcutaneously in whole with no leads within the heart. However, each of these technologies are mired with problems including patient discomfort and as in the case of the S-ICD, a big surgical pocket at implant, and negative impact due to the ICD relatively large generator´s size, the need to replace their batteries every 5-7 years which requires a new replacement operation as well as use of intensive fluoroscopy with occasional lead extractions. NewPace has developed the Implantable Subcutaneous String Defibrillator (ISSD), to address the need for better patient outcomes due to SCA, providing more reliable and safe cardiac rhythm management. The overall objectives of the project are to complete development of the ISSD device, undertaking a series of preclinical tests to confirm its safety and effectiveness, and eventually validating it through a clinical trial with European medical centres. Completion of these objectives will result in a product that is ready for the market.