Cardiology Quiz 5 Flashcards
A first-degree heart block has a PR interval greater than 0.20 seconds because:
A) depolarization of the atria occurs at a slightly slower rate than one would expect.
B) each impulse that reaches the AV node is delayed slightly longer than expected.
C) impulses generated by the SA node traverse the AV node at an accelerated rate.
D) the primary pacemaker is not the SA node, but rather an ectopic atrial pacemaker.
B) each impulse that reaches the AV node is delayed slightly longer than expected.
A key to interpreting a Mobitz type II second-degree heart block is to remember that:
A) in this type of heart block, the PR interval gets progressively longer until a P wave is not conducted.
B) the PR interval of all of the conducted P waves and their corresponding QRS complexes is constant.
C) most type II second degree AV blocks have more than two nonconducted P waves that occur in succession.
D) unlike a Mobitz type I second-degree heart block, a type II heart block is always regular.
B) the PR interval of all of the conducted P waves and their corresponding QRS complexes is constant.
A second-degree heart block, Mobitz type I, occurs when:
A) more than one successive impulse from the SA node is blocked at the AV node and is not allowed to enter the ventricles.
B) each successive impulse is progressively delayed, until one impulse is blocked from entering the ventricles.
C) the PR interval progressively grows narrower, until there is a P wave that is not followed by a QRS complex.
D) every other impulse generated by the SA node is blocked at the AV node and does not depolarize the ventricles.
B) each successive impulse is progressively delayed, until one impulse is blocked from entering the ventricles.
On the ECG strip, a third-degree AV block usually appears as a:
A) narrow QRS complex rhythm with a rate less than 60 beats/min.
B) slow, wide QRS complex rhythm with inconsistent PR intervals.
C) slow, narrow QRS complex rhythm with irregular P-P intervals.
D) wide QRS complex rhythm with a rate between 50 and 70 beats/min.
B) slow, wide QRS complex rhythm with inconsistent PR intervals.
Which of the following occurs at the AV node during a third-degree heart block?
A) Impulses bypass the AV node and enter the ventricles.
B) Every third impulse is allowed to enter the ventricles.
C) All impulses are blocked from entering the ventricles.
D) There is an abnormal delay in conducting impulses.
C) All impulses are blocked from entering the ventricles.
Which of the following statements regarding second-degree heart block is correct?
A) Most second-degree heart blocks are transient in nature and resolve in the prehospital setting without the need for intervention in the emergency department.
B) Second-degree heart block is characterized by inconsistent PR intervals, a QRS complex greater than 0.12 seconds, and a ventricular rate less than 40 beats/min.
C) More than half of all second-degree heart blocks cause hemodynamic compromise and require transcutaneous cardiac pacing in the prehospital or hospital setting.
D) Second-degree heart block occurs when an impulse reaching the AV node is occasionally prevented from proceeding to the ventricles and causing a QRS complex.
D) Second-degree heart block occurs when an impulse reaching the AV node is occasionally prevented from proceeding to the ventricles and causing a QRS complex.
Which of the following statements regarding treatment for a first-degree heart block is correct?
A) Treatment is generally not indicated unless the rate is slow and cardiac output is impaired.
B) First-degree heart block is often accompanied by a compensatory tachycardia that requires treatment.
C) Most first-degree heart blocks are associated with significant bradycardia and require atropine.
D) Transcutaneous cardiac pacing should be initiated without delay for patients with a first-degree heart block.
A) Treatment is generally not indicated unless the rate is slow and cardiac output is impaired.
