![]() Pacemakers are electronic devices programmed to pace (deliver the depolarizing current) the specified cardiac chamber and sense the intrinsic cardiac activity in the respected chamber. Total Atrial Refractory Period (TARP): The sum of AV delay and post-ventricular atrial refractory period.Pacemaker becomes blind for atrial events. Post Ventricular Atrial Blanking (PVAB): This is the time duration after the ventricular event when a pacemaker does not sense any atrial event.It sees the activity but does not reset the timing cycle. Post Ventricular Atrial Refractory Period (PVARP): It is a time duration after the ventricular event when a pacemaker does not react to a sensed atrial activity.Paced AV Delay: It is a time duration after atrial pacing at which the pacemaker will pace the ventricle if it does not sense the intrinsic activity.Sensed AV Delay: It is a time duration after sensed atrial activity at which the pacemaker will pace the ventricle if it does not sense the intrinsic activity.Maximum Tracking Rate (MTR): Maximum atrial rate at which a dual-chamber pacemaker tracks the sensed atrial activity and paces the ventricle.Upper Rate Limit: The maximum rate at which a pacemaker can pace in the absence of intrinsic activity.Lower Rate Limit: Base rate or slowest rate that the pacemaker will allow the patient's heart to go.Different timing cycles are programmed in a pacemaker for its functioning. Ī pacemaker has two primary functions, pacing (an electrical stimulus for myocardial depolarization) and sensing (detecting intrinsic electrical activity and wave of depolarization). The sensing of the innate activity of the heart is also a function of the leads. ![]() Pacemaker leads conduct the depolarizing potential to the myocardium. Pulse generator houses the battery and other electronics which control the modes of the pacemaker. Pacemakers consist of two main components: a pulse generator and the leads. This review will discuss the common pacing system problems of a cardiac implantable electronic device (pacemaker). The periodic evaluation of an implanted pacemaker is necessary to optimize programming and to identify correctable problems. ĭespite their success, electronic pacemakers have limitations, including complications related to implantation, limited battery life, the potential for infection, lack of physiologic autonomic responsiveness, and size restriction in younger patients. This process leads to excitation-contraction coupling resulting in the contraction of myocardial tissue. These pacing devices provide an external electrical stimulus that leads to depolarization of myocytes and helps maintain the electrical excitability of the heart tissue. The current standard of care for symptomatic bradyarrhythmias due to conduction system diseases is the implantation of a cardiac implantable electronic device. Acquired conditions such as myocardial infarction, age-related degeneration, procedural complications, and drug toxicity are the major causes of the native conduction system malfunction. Several diseases and conditions affect the conduction system by involving impulse generation, impulse propagation, or both. The failure of this intrinsic electrical conduction in the heart can result in different arrhythmic problems. This movement of electric potential in an orderly manner controls the rhythmic contraction of the heart's chambers. This innate electrical potential moves from the sinoatrial node to the atrioventricular node and finally into the His-Purkinje system. The cells present in the sinus node have innate automaticity, which starts the electrical activity in the heart. The sinoatrial node acts as the natural pacemaker of the heart. This functioning of the heart depends on the cardiac conduction system, which includes impulse generators (e.g., sino-atrial node) and the impulse propagating (His-Purkinje) system. The human heart is a pivotal organ in the circulatory system, and it beats more than 2 billion times during normal life. Summarize the importance of the interprofessional team in the management of the patient with pacemaker malfunction and the preoperative assessment of patients with pacemakers.Review the underlying mechanisms of malfunction of the pacemaker. ![]()
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