ACTIVITY 4 Electrocardiography 1 Label the terms for an ECG in Figure 28.4, a normal ECG. 2 Record an ECG at rest and af

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Activity 4 Electrocardiography 1 Label The Terms For An Ecg In Figure 28 4 A Normal Ecg 2 Record An Ecg At Rest And Af 1 (76.6 KiB) Viewed 30 times

ACTIVITY 4 Electrocardiography 1 Label the terms for an ECG in Figure 28.4, a normal ECG. 2 Record an ECG at rest and after exercise if equipment is available. • Do this activity with a lab partner. Choose who will be the subject and who will do the recording. Swab the skin where the electrodes will be placed with alcohol, and then apply electrode paste, jelly, or cream to the same area (see Figure 28.3). • Attach the electrodes to the anterior surface of each wrist and to the inside area of each ankle. Connect the patient cables to the electrodes and also to the recording instrument. • Follow your instructor's directions for recording the ECG with your equipment. • Label the P wave, QRS complex, T wave, P-Q interval, S-T segment, and Q-T interval on the recorded ECG. WebActivities. Go to www.wiley.com/college/allen. Click on the picture of your lab manual, then on Student Com- panion Site, WebActivities, and Exercise 28 to calculate lengths of ECG segments. Milos (V) 1.0 0.5 -0.5 . P wave . P-Q interval • QRS complex . Q-T interval . S-T segment . Twave el 0 0.2 0.4 0.6 0.8 Seconds 1 2 3 FIGURE 28.4 Section of a normal ECG, Lead IL EXERCISE 28 CARDIAC CYCLE 461 3. Determining Heart Rate Using an ECG In an adult, a heart rate of 60 to 100 beats/min is a normal sinus rhythm (NSR). A heart rate above 100 beats/min is called tachycardia, but in young children, this rate would be considered normal. Heart rates below 60 beats/min are normal for highly conditioned individuals, but in other adults, heart rates below 60 beats/min are called brady- cardia. Neither condition is considered to be pathological. Prolonged tachycardia can develop into ventricular fibrillation, rapid uncoordinated heart contractions that do not pump blood. ACTIVITY 5 Heart Rate Calculations 1 Calculate the heart rate for the ECGs in Figure 28.5(a). (b), and (c). • Heart rate can be easily calculated from an ECG. Standard ECGs are printed on paper moving at a paper speed of 25 mm/sec. Therefore, the distance of 1 mm (1 small square on standard ECG paper) is equivalent to 0.04 sec. Measure the distance between the start of one P wave to the start of the next P wave by counting the number of small squares between them. For ease of measurement, the distance between R waves can be measured instead (see Note below). • Multiply the number of squares (1 square 1 mm) by 0.04 sec to determine the length of one heart beat in seconds (sec/beat). This is the length of one cardiac cycle. . Since there are 60 seconds in 1 minute, divide 60 by your answer to calculate beats/min. This is the heart rate. Example: Step 1-20 small squares (20 mm) are counted between two P waves. Step 2-0.04 sec x 20 mm - 0.8 sec/beat 60 sec/min 75 beats/min 0.8 sec/beat Step 3 NOTE: The heart rate calculated using the distance between R waves is the ventricular rate, while the heart rate calcu lated using the distance between P waves is the atrial rate. In normal sinus rhythm (NSR), the atrial rate equals the ventricular rate.