View source for Answer DV Case 4

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[[Image:DVA0004.jpg|700px|thumb|left|DV Case 4. Click on image for enlargement.]]
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==Questions==
This ECG shows pauses in the heart rhythm. The patient felt light headiness
#What is the base rhythm?
#Is there evidence for sino atrial block?
#What is the cause of the pauses in the heart rhythm?
#Is there a pacemaker indication?
#what is your next step in your workup?
==Answers==
# The rhythm shows inverted P-waves in the inferior leads indicative of [[Atrial_Rhythm|atrial rhythm]].
# The answer on this question is difficult. An atrial rhythm can be the result of SA block. This ECG however cannot produce the proper answer. The use of beta-blockers for instance, could cause a marked lowering of the sinus rhythm, allowing for an atrial escape rhythm, which is slow as well.
# The cause of the pauses in the atrial rhythm are atrial premature beats, blocking the exit of the atrial prevailing atrial rhythms. These [[Atrial_Premature_Complexes|atrial premature beats]] can be appreciated when looking at the T-waves of the conducted beats preceding the pause.
# This question cannot be answered on this ECG. Pacing could be indicated as the patient has dizzy spells. However, blocked atrial beats per se are no pacemaker indication.
# The proper workup could be: 
##stopping medication that lowers the sinus node frequency (B-blockers, funny current blockers, calcium channel blockers)
##a long term ECG recording. 
##measuring the sinus node recovery time is questionable.