Download Slide ()

Disturbances of Cardiac Rate and Rhythm II In all diagrams, the audible heart sounds are the only physical signs to indicate the presence and operation
of the mechanisms. A. Second-degree AV block is depicted with a 2:1 ratio. Alternate stimuli from the atria are blocked in the AV node, so the ventricles
beat only half as fast as the atria. The only physical sign is a slow regular heartbeat with first sounds of equal intensity. B. Complete AV block is depicted,
in which the ventricles beat independently of the atria and usually assume a slow rate, below 50/min, that accelerates little with exertion. A louder-thancommon first sound occurs when ventricular filling is augmented by an atrial contraction occurring by chance at the optimal time, this is called by the
French—the “bruit de canon.” C and D. When ventricular beats are regular with rates between 160 and 220/min, two conditions must be distinguished. C.
Source: Vital Signs, Anthropometric Data, and Pain, DeGowin’s Diagnostic Examination, 10e
Paroxysmal atrial tachycardia. D. Atrial flutter. Vagal stimulation may convert paroxysmal atrial tachycardia to normal rhythm, but there is no temporary
Citation:the
LeBlond
RF, Brown
DD, Suneja
M, stimulus
Szot JF. is
DeGowin’s
Diagnostic
Examination, 10e; 2015 Available at: http://mhmedical.com/
slowing. In contrast,
only response
of flutter
to vagus
slowing for
a few beats.
Accessed: May 04, 2017
Copyright © 2017 McGraw-Hill Education. All rights reserved