![]() ![]() 5 Pacing ArtifactsĪ simple implanted pacer’s activity is generally not perceptible on a normal ECG trace because the very fast pulses-with widths of microseconds-get filtered out, but in any case, they are too narrow to appear on a trace with resolution in the milliseconds. ![]() As of 2010, the National Academy of Engineering states that over 400,000 pacemakers are implanted in patients every year. Pacemakers must be low-power devices, as they operate with a small battery that typically has a 10-year lifespan. They contain the circuitry necessary to monitor the electrical activity of the heart through implanted leads and to stimulate the heart muscle when required to ensure a regular heartbeat. Implantable pacemakers (Figure 5) are typically lightweight and compact. Fluoroscopy images showing pacemaker lead placement. The right ventricle lead is positioned at the apex of the right ventricle. The right atrium lead is pointing up and is placed in the right atrium. Figure 4(b) shows a fluoroscopy image of typical lead placement for a dual-chamber pacemaker. The partially seen lead, indicated by the red arrow, is the left ventricle lead (the red arrow points to the tip of the electrode). The dashed black arrow points to the right ventricle lead. In this typical lead placement, the black arrow points to the right atrium lead. It is lying on the right atrium with the apex of the heart pointing to the right and downward. You can see a light outline of the heart-a static view of a beating heart. Such images are difficult for lay persons to interpret. This is the image that physicians use to place the leads. Cardiac resynchronization therapy (CRT) devices include an ICD as part of the system.Ī CRT device is seen in the fluoroscopic image of Figure 4(a). These devices actually improve cardiac output, allowing the heart to recover to a certain degree. Implantable cardiac resynchronization (ICR) devices retime the ventricles by pacing both ventricles and usually one atrium. ![]() This forms a positive feedback system, further aggravating the heart. Heart failure can occur when the heart becomes enlarged, lengthening its conduction paths and upsetting the timing of the ventricular contractions. Modern ICDs can also treat many bradycardia arrhythmias. This very serious condition is treated with implantable cardiac defibrillators (ICDs). In another class of arrhythmias, called tachycardia, the heart beats too fast. Positions of implanted pacemaker and leads for different types of pacemakers (RA-right atrium, RV-right ventricle, LV-left ventricle). A typical surgical intervention for this condition would be to implant a pacemaker device (pulse generator) just under the skin of the patient’s chest, with endocardial leads routed through the veins directly to the heart, as shown in Figure 3. For example, bradycardia occurs when the heart beats too slowly or misses beats. When the electrical system doesn’t work perfectly, many different heart conditions can occur. Graphical ECG representation of electrical action during heart muscle contractions. Their contraction (the R wave) moves oxygenated blood from the left ventricle into and through the body-and deoxygenated blood from the right ventricle to the lungs. From the AV node, the electrical signal propagates, via the His-Purkinje system, to the ventricles, causing the ventricle muscles to contract. This electrical impulse generates the P wave, which can be seen on the ECG capture in Figure 2. Heart muscle showing SA (1) and AV (2) nodes. The SA node acts as the pacemaker for the system (Figure 1). The heart, a biochemical-electromechanical system, develops an electrical impulse that travels from the sinoatrial (SA) node in the upper right atrium to the atrioventricular (AV) node. ![]() This article describes the nature of pacing artifacts and introduces a device and methodology to detect them. Buried in noise and larger cardiac signals, these artifacts can be difficult to detect. The electrical signature-or artifacts-of the pacing signal consists of small, narrow pulses. When heart patients with implanted pacemakers undergo electrocardiogram (ECG) testing, a cardiologist must be able to detect the presence and effects of the pacemaker. Detecting and Distinguishing Cardiac Pacing Artifacts ![]()
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