Glossary
Introduction
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Premature Ventricular Contractions
Six PVC-type selections of focus and timing:
• a left-focus premature ventricular beat with standard timing, 20 % premature;
• a left-focus premature ventricular beat with early timing, 33 % premature;
• a left-focus premature ventricular beat with very early timing, 65 %
premature, which starts during the T wave of the previous beat;
• a right-focus premature ventricular beat with standard timing, 20 %
premature;
• a right-focus premature ventricular beat with early timing, 33 % premature; or
• a right-focus premature ventricular beat with very early timing, 65 %
premature, which starts during the T wave of the previous beat.
A premature ventricular contraction or PVC is an extra beat consisting of an
abnormally wide and unusual QRS complex originating in an ectopic pacemaker
in the ventricles. Early ventricular PVCs occur close to the preceding beat.
Moreover, R-on-T PVCs, which are characterized by a beat that falls on the T
wave of the preceding QRS-T complex, are especially inauspicious because of
their potential to cause ventricular tachycardia or ventricular fibrillation.
Pulse
The rhythmical throbbing of arteries produced by regular contractions of the
heart.
Pulse Oximeter
A non-invasive, arterial, oxygen-saturation monitor that measures the ratio of two
principle forms of hemoglobin in the blood.
Purkinje Network
The dense collection of Purkinje fibers, which are dispersed throughout the
myocardium and which represent the terminal portion of the heart's electrical
conduction system.
PVCS
Premature ventricular contractions.
PVCS: 6, 12, or 24 Per Minute
PVCs scattered among normal beats AT 80 BPM, so that PVCs take place 6, 12,
or 24 times every minute. Premature ventricular contractions may occur
independently (even in healthy individuals), as well as in groups and/or for a
number of times every minute.
QRS Complex
The part of the P-QRS-T wave that records ventricular depolarization and
contraction.
R-Value
The non-pulsating components of tissue, specifically the tissue bed, the venous
blood, the capillary blood, and nonpulsatile arterial blood. Also referred to as the
DC component.
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