The nurse admits a patient into the emergency department who complains of light-headedness and nausea

Question

During the assessment, the nurse determines that the radial pulse is 42 and regular, the QRS complex is within normal limits, and there is no measurable PR interval because there is no consistent relationship between the P waves and the QRS complexes. How would the nurse interpret this dysrhythmia? 1. Third-degree AV heart block
2. Sinus bradycardia
3. Supraventricular tachycardia
4. Sinus arrest

Answer 1

1
Rationale 1: Third-degree AV block, or complete block, is the independent excitation and contraction of the atria and ventricles due to the inability of any atrial impulses to reach the ventricles. In other words, the top and bottom of the heart are not communicating; they are beating independently. Hence there are no consistent PR intervals.
Rationale 2: Sinus bradycardia occurs when the SA node is firing at a rate of less than 60 beats per minute. There is a consistent PR interval with sinus bradycardia.
Rationale 3: Supraventricular tachycardia has a rate greater than 100 beats per minute.
Rationale 4: Sinus arrest is a momentary cessation of sinus impulse formation (SA node failure), which causes the absence of the PQRST complex. The remainder of the beats have normal PR intervals.