How is a biventricular pacemaker or defibrillator implanted?

During either pacemaker or defibrillator implantation, an extra “third wire,” also known as a left ventricular lead, is placed. This is threaded to the heart the same way as other pacemaker or defibrillator leads, except it is then further threaded from the right atrium into another vein that leads to the surface of the left ventricle. Getting that third wire in place is trickier but achievable in about 95% of cases. Otherwise, the rest of the procedures are the same as a standard pacemaker or defibrillator implantation. Please see the descriptions of those procedures.