Chapter 8 – Basic ECG Interpretation Critical Thinking Checkpoint Answers
A patient has a history of chronic atrial fibrillation. He takes digitalis. He recently developed
nausea and vomiting. Twenty-four hours later, he was still vomiting. He told his wife he felt like his
heart was “just not working right,” so they went to the ER. Upon admission, he was connected to
the ECG monitor. The nurse obtained the rhythm strip below.
<<INSERT Critical Thinking Checkpoint Rhythm Strip 1 >>
1. What is this rhythm? ANSWER: Atrial fibrillation. Note the absence of P waves
2. What effect does this rhythm have on cardiac output? ANSWER: Loss of the atrial kick can decrease
cardiac output by as much as 25%.
3. What lab tests would you anticipate would be needed? ANSWER: Serum electrolytes, particularly
potassium and magnesium. Also a digitalis level.
4. Name three dysrhythmias that can occur as a result of digitalis toxicity. ANSWER: Your answer
should include any three of the following: atrial tachycardia, AV blocks, junctional and ventricular
dysrhythmias.
5. The patient was admitted to the coronary care unit. Three hours later, the monitor alarm went off for
the following rhythm. What is your interpretation? ANSWER: Asystole
<<INSERT: Critical Thinking Checkpoint Rhythm Strip 2 >>
6. What interventions and medications would you anticipate for this rhythm? ANSWER: CPR, atropine,
epinephrine
7. The patient was successfully resuscitated. A pacemaker was inserted. A few hours later, the following
rhythm was noted. What is your interpretation? ANSWER: Loss of capture. The pacemaker spikes
are not followed by a QRS complex.
<<INSERT Critical Thinking Checkpoint Rhythm Strip 3 F>>