Sensing vectors of the subcutaneous implantable cardioverter defibrillator(A) Distal electrode ring; (B) proximal electrode ring; (C) can. Primary vector from proximal electrode ring to can (red arrow), secondary vector from distal electrode ring to can (blue arrow) and alternate vector from distal electrode ring to proximal electrode ring (yellow arrow) are shown. Abbreviations: ECG, electrocardiogram.