Failure to capture pacemaker generator#

Occasional FDA recalls are issued for products with excessive failure rates or failures that pose a particular risk to the patient. Pacemaker manufacturers publish at least twice-yearly product performance reports, which closely track the performance of their products. Failure is much more common in leads, the weakest link in the system. Malfunction of pacemaker generators and pacemaker leads may occur. Sensed events are used by the pacemaker logic to appropriately time the pacing impulses.

Failure to capture pacemaker generator#

Sensing refers to detection by the generator of intrinsic atrial or ventricular depolarization signals that are conducted up a lead. Pacing refers to depolarization of the atria or ventricles, resulting from an impulse (typically 0.5 msec and 2 to 5 volts) delivered from the generator down a lead to the heart. The two basic functions of the pacemaker system are pacing and sensing.

Less commonly, leads are attached directly to the epicardial surface of the heart with either a helical screw or a suture-on-plaque electrode via a thoracotomy (вЂњepicardial leadsвЂќ). The vast majority of pacemaker leads are inserted transvenously from the generator to the endocardium (вЂњtransvenous leadsвЂќ). The primary portions of a lead are the lead body, containing one or two conductors encircled by insulation the distal end, which contains one or two exposed electrodes in proximity to the myocardium, as well as a fixation with tines and a connector pin at the proximal end of the lead, which is plugged into the header of the generator. Leads are thin, flexible, insulated wires that conduct electrical impulses from the pacemaker generator to the heart and also relay electrical signals from the heart back to the generator. The other components of the pacemaker system are the leads. Pacemakers should be monitored with programmers or wireless communication every 3 to 6 months. When the generator has about 3 months of functional battery life remaining, interrogation with a programmer will signal an alert (вЂњelective replacement indicatorвЂќ or ERI) that a generator change should be performed soon.

The life span of a particular generator in a particular patient is largely dependent on percent pacing, programmed voltage and pulse width, and electrical pacing impedances. Pacemaker batteries are designed to have predictable depletion over time, which can be monitored by their cell voltage and cell impedance. There is also an outer, clear epoxy header into which the leads are placed and secured. The primary components of the generator are a lithium-iodine battery (about 25% of the total volume), the hybrid circuit (consisting of a microprocessor and resistors, etc.), and a small computer controlling device, all of which are contained in a hermetically sealed titanium casing. The pacemaker system is composed of a pulse generator and one or more leads that connect the generator to the heart. The vast majority of pacemakers (>98%) are implanted due to a patientвЂ™s inability to maintain an adequate heart rate secondary to either symptomatic bradycardia or bradycardia due to block somewhere within the intrinsic electrical conducting system (sinoatrial node, atrioventricular junction, His-Purkinje system). The pacemaker uses electrical impulses to stimulate myocardial contraction. The artificial pacemaker is a medical device that is surgically implanted, most commonly in the subcutaneous tissues overlying the prepectoral fascia in the upper chest. General description of procedure, equipment, technique