18. The Heart

When analyzing an ECG, you measure the time between the beginning of the QRS complex and the end of the T wave. Which physiological events are included in this interval?

During an ECG analysis of a patient, the doctor detects an abnormally prolonged PR interval. Which stage of cardiac conduction is most likely responsible for this delay?

Fibrillation can happen in either the atrial or the ventricles. When fibrillation happens in the ventricle it is usually immediately be life threatening. Which ECG below do you think shows ventricular fibrillation?

A varsity athlete went for their physical, which included an ECG. The doctors noticed that the student’s heart rate was unusually low, but they told the student not to worry. What term would the doctors include in their chart to describe the student’s heart?

Draw a normal ECG pattern. Label and explain the significance of its deflection waves.

An ECG provides information about:

a. Cardiac output

b. Movement of the excitation wave across the heart

c. Coronary circulation

d. Valve impairment

More than one choice may apply.

Atrial repolarization coincides in time with the

a. P wave

b. T wave

c. QRS wave

d. P-Q interval

Explain what each of the following terms represents on an electrocardiogram (ECG).

a. P wave

b. QRS complex

c. T wave

d. P-R interval

e. S-T segment

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

The ventricular ejection phase generally correlates with the S-T segment and the T wave on the ECG.