Artificial cardiac pacemaker
An artificial cardiac pacemaker, commonly referred to as simply a pacemaker, is an implanted medical device that generates electrical pulses delivered by electrodes to one or more of the chambers of the heart. Each pulse causes the targeted chamber(s) to contract and pump blood,[3] thus regulating the function of the electrical conduction system of the heart.
"Pacemaker" redirects here. For other uses, see Pacemaker (disambiguation).Artificial cardiac pacemaker
The primary purpose of a pacemaker is to maintain an even heart rate, either because the heart's natural cardiac pacemaker provides an inadequate or irregular heartbeat, or because there is a block in the heart's electrical conduction system. Modern pacemakers are externally programmable and allow a cardiologist to select the optimal pacing modes for individual patients. Most pacemakers are on demand, in which the stimulation of the heart is based on the dynamic demand of the circulatory system. Others send out a fixed rate of impulses.[4]
A specific type of pacemaker, called an implantable cardioverter-defibrillator, combines pacemaker and defibrillator functions in a single implantable device.[5] Others, called biventricular pacemakers, have multiple electrodes stimulating different positions within the ventricles (the lower heart chambers) to improve their synchronization.[6]
Conduction System Pacing[edit]
Conventional placement of ventricular leads in or around the tip or apex of the right ventricle, or RV apical pacing, can have negative effects on heart function. It has been associated with increased risk of atrial fibrillation, heart failure, weakening of the heart muscle and potentially shorter life expectancy. His bundle pacing (HBP) leads to a more natural or perfectly natural ventricular activation and has generated strong research and clinical interest. By stimulating the His–Purkinje fiber network directly with a special lead and placement technique, HBP causes a synchronized and therefore more effective ventricular activation and avoids long-term heart muscle disease. HBP in some cases can also correct bundle branch block patterns.[21][22]
Considerations[edit]
Insertion[edit]
A pacemaker may be implanted whilst a person is awake using local anesthetic to numb the skin with or without sedation, or asleep using a general anesthetic.[25] An antibiotic is usually given to reduce the risk of infection.[25] Pacemakers are generally implanted in the front of the chest in the region of the left or right shoulder. The skin is prepared by clipping or shaving any hair over the implant site before cleaning the skin with a disinfectant such as chlorhexidine. An incision is made below the collar bone and a space or pocket is created under the skin to house the pacemaker generator. This pocket is usually created just above the pectoralis major muscle (prepectoral), but in some cases the device may be inserted beneath the muscle (submuscular).[26] The lead or leads are fed into the heart through a large vein guided by X-ray imaging (fluoroscopy). The tips of the leads may be positioned within the right ventricle, the right atrium, or the coronary sinus, depending on the type of pacemaker required.[25] Surgery is typically completed within 30 to 90 minutes. Following implantation, the surgical wound should be kept clean and dry until it has healed. Some movements of the shoulder within a few weeks of insertion carry a risk of dislodging the pacemaker leads.[25]
The batteries within a pacemaker generator typically last 5 to 10 years. When the batteries are nearing the end of life, the generator is replaced in a procedure that is usually simpler than a new implant. Replacement involves making an incision to remove the existing device, disconnecting the leads from the old device and reconnecting them to a new generator, reinserting the new device and closing the skin.[25]
Current and prior manufacturers of implantable pacemakers