When is this procedure indicated?
Candidate patients for such a device are those who have survived a cardiac arrest (in secondary prevention), and those with heart disease (hypost-ischemic or primary) potentially at risk of developing dangerous ventricular arrhythmias (primary prevention). In addition to an antitachycardia function, defibrillators also have an antibradycardia function, act as pacemakers, and are, therefore, able to stimulate the heart in case the heart rate becomes too low.
How is it performed?
Defibrillator implantation is very similar to pacemaker implantation and is therefore performed under local anesthesia. The first part of the implantation concerns the positioning of the leads, i.e. the "electric wires" that reach the heart; their number can vary from one to three depending on the type of device that needs to be implanted. Leads are inserted within a vein (subclavian or cephalic, usually left).
The leads are directed under fluoroscopic guidance (X-rays) inside the cardiac chambers (right atrium, right ventricle, coronary sinus) and positioned at the points where they can best sense cardiac activity and where they can stimulate the heart using the least possible energy, all guided by a portable computer/programmer. After verifying the stability of the catheters and their electrical parameters, they are attached to the underlying muscle and then connected to the defibrillator housed subcutaneously through a small incision that is then closed with suture thread.
Generally, hospitalization lasts 2-3 days. Following implantation, after a brief period of bed rest, an electronic check of the device and a chest x-ray are performed to evaluate lead placement. Implantable defibrillator patients should subsequently undergo a six-monthly device check. Implantable defibrillator patients should subsequently undergo a six-monthly device check.
The most frequent short-term complications related to implantation maneuvers are the formation of a local hematoma at the implant site (which generally reabsorbs spontaneously in a few days), possible damage to the venous vessels used for access (with consequent thrombosis and possible phlebitis), possible pneumothorax in case of subclavian vein puncture (passage of air into the pleural cavity, in most cases asymptomatic and self-solvent, rarely requiring placement of temporary drainage). Rarely, pericardial effusion secondary to myocardial lead wall perforation may occur, which in some cases may require placement of temporary drainage.
Long-term complications are similar to and as rare as those of the pacemaker, and concern the risk of infection, lead malfunction (from rupture and detachment), and the risk of damage to the lead. In some cases, pacemaker removal or lead replacement is required.