Scope of this Product Comparison
This Product Comparison covers single-channel electrocardiographs that record the electrocardiogram (ECG) from one lead configuration at a time. Both battery- and line-powered units are included. Electrocardiographs that can record on a single channel or on three or more channels (multichannel) are alsocovered, as are single-channel units that perform ECG waveform analysis as an optional feature only. Single-channel telephone ECG transmitter/receiver systems have been excluded, although many of the electrocardiographs included in this report can be interfaced with them. For additional information on ECG recording and monitoring, see the following Product Comparisons: • Defibrillators, External, Manual;Defibrillator/ Pacemakers, External • Electrocardiographs, Multichannel; Interpretive • Physiologic Monitoring Systems, Acute Care; Neonatal; ECG Monitors • Physiologic Monitoring Systems, Telemetric; ECG Monitors, Telemetric • Recorders, Electrocardiography; Scanners, ECG
Electrocardiographs detect the electrical signals associated with cardiac activity and produce an ECG, a graphicrecord of the voltage versus time. Single-channel electrocardiographs are used to diagnose cardiac abnormalities, determine a patient’s response to drug therapy, and reveal trends or changes in heart function. Single-channel electrocardiographs record and print reports of electrical activity from only one lead configuration (one set of electrodes) at a time, although they receive electricalsignals from as many as 12 leads. Leads are recorded in a sequence that can be operator selected and/or automatically determined. ECGs are used to diagnose and assist in treating arrhythmias and some types of heart disease. They differ from ECG monitors, which are designed to provide a continuous display of the ECG waveform and other physiologic measurements on a screen and warn of potentiallylife-threatening or precursor rhythms.
This Product Comparison covers the following device term and product code as listed in ECRI’s Universal Medical Device Nomenclature System™ (UMDNS™): • Electrocardiographs, Single-Channel [11-413]
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Bipolar and Augmented Leads
Figure 1. The three groups of lead configurations
In addition, ECG monitors usually display only one or two leads of the ECG, with less signal fidelity than an electrocardiograph. are obtained by measuring the voltagebetween one limb electrode and the average of the other two. Augmented leads require three electrodes and are designated according to limb — right arm (aVR), left arm (aVL), and left leg (aVF). Precordial leads measure the voltage between one chest electrode (designated V1 through V6) and the average of all the limb electrode voltages (see Fig. 1). Each of the 12 standard leads presents a differentperspective of the heart’s electrical activity, producing ECG waveforms whose P waves, QRS complex, and T waves vary in amplitude and polarity (see Fig. 2). Many cardiac problems can be characterized by particular variations in the size, shape, duration, and polarity of these waves; by a change in the length or amplitude of a segment between waves (e.g., ST segment); by the appearance of additionalwaves; and/or by variations in rhythm. The recordings can also provide the cardiologist with information regarding the size, shape, and orientation of the heart within the chest. Other lead configurations include the Frank system and Cabrera leads. The Frank configuration measures voltages from electrodes applied to seven locations — the forehead or neck, the center spine, the midsternum, the...
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