# Heart Sounds Exercise 1: ECG at rest Study Exercise

### Question Description:

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Heart Sounds Exercise 1: ECG at rest Study Exercise Use the Comments panel to indicate on the recording the P-wave, the QRS complex, and the T-wave. Study Questions ECG Amplitude and Duration ECG Interval and Rate Component Amplitude (mV) Duration (s) Pair P wave 0.3 1 2 3 QRS complex 0.251 T wave 0.137 1. 0.056 0.6906 Interval (s) Heart rate (BPM) What can you say about the amplitude of the various waves in different cardiac cycles? 2. The P wave and the QRS complex represent depolarization of the atrial and ventricular muscle respectively. Why does the QRS complex have the largest amplitude? 3. In steps 7 and 8 heart rate was calculated based upon the peak-to-peak interval of the R waves. Was there variability between the beats? Would you expect the interval between beats to be identical? Why or why not? 4. The range for a normal resting heart rate is 60 to 90 bpm. A trained athlete could have a resting heart rate of 45 to 60 bpm. Why might a very fit person have a slower heart rate than someone of average fitness? Exercise 2: ECG variation Variation in ECG Component Amplitudes and Durations Voluntee P amplitude r (mV) 0.019 -0.036 -0.273 -0.214 -0.187 P duration (s) 4.413 4.315 6.186 7.469 7.513 R amplitude (mV) -0.014 0.03 -0.29 -0.173 -0.125 QRS duration (s) 4.424 4.318 6.198 7.479 7.518 T amplitude (mV) 0.005 0.141 -0.206 -0.214 -0.104 T duration (s) 4.44 4.331 6.217 7.499 7.531 Study Questions 1. Are the amplitudes and durations of the various waves in different individuals similar or very different? 2. What variations in heart rate did you observe between individuals? Exercise 3: ECG and heart sounds ECG and Heart Sounds R to first sound (s) T to second sound (s) 0.036 0.084 Study Questions 1. Explain why ventricular contraction (systole) and the ‘lub’ sound occur immediately after the QRS complex. 2. Explain why ventricular relaxation (diastole) and the ‘dup’ sound occur after the T wave. Exercise 4: ECG and phonocardiography ECG and Phonocardiography R to first sound (s) T to second sound (s) 4.655 4.73 Study Question 1. Your "lub-dub" recordings probably show some differences from the correct timing of the heart sounds as judged by phonocardiography. How can you account for this difference? ©2005-2007 ADInstruments Read more