Cardiac rhythm monitors & equipment Flashcards
Which pathway depolarizes the left atrium?
a. Thorel tract
b. Bachmann bundle
c. Kent bundle
D. Wenckebach tract
b. Bachmann bundle
There are _________ internodal tracts that travel from the SA node to the AV node
3:
anterior internodal tract
middle internodal tract
posterior internodal tract
The anterior internodal tract gives rise to the
Bachmann bundle
The middle internodal tract gives rise to the
Wenckebach tract
The posterior internodal tract gives rise to the
Thorel tract
Conduction velocities of the cardiac conduction pathway from slowest to fastest are
AV node
SA node
myocardial muscle cells
His bundle
Bundle branches
Purkinje fibers
There’s a band of connective tissues that electrically isolates the
atria from the ventricles making the AV node the gatekeeper of electrical impulses into the ventricle
The SA & AV nodes conduct at
0.02-0.10 m/sec
The myocardial muscle cells conduct at
0.3-1 m/sec
The His bundle, bundle branches, and Purkinje fibers conduct at
1-4 m/sec
Conduction velocity is a function of
resting membrane potential
amplitude of the action potential
rate of change in membrane potential during phase O
Conduction velocity is affected by:
ANS tone
Hyperkalemia induce closure of fast Na+ channels
Ischemia
acidosis
antiarrhythmic drugs
The James fiber accessory pathway is
atrium to AV node
The Atrio-hisian fiber accessory pathway is
atrium to His bundle
The Kent’s bundle accessory pathway is
atrium to ventricle
The Mahaim bundle accessory pathway is
AV node to ventricle
Key components of the EKG include
P wave
PR-interval
QRS complex
ST segment
T wave
What happens at the P wave?
atrial depolarization begins
What happens at the PR interval?
atrial depolarization complete
What happens at the QRS complex?
atrial repolarization + ventricular depolarization
What happens at the ST-segment?
ventricular depolarization complete
What happens at the T wave?
ventricular repolarization begins
___________ can cause PR-interval depression
Pericarditis
Peaked T waves can be caused by
myocardial ischemia
hyperkalemia
left ventricular hypertrophy
intracranial bleeding
Q waves suggest myocardial infarction if the amplitude is _____________, duration is _________-, or depth is ___________
greater than 1/3rd of the R wave; duration is greater than 0.04 seconds, or depth is greater than 1 mm
What is used as a reference point for measuring ST elevation and depression?
the PR segment b/c it is an isoelectric line
By measuring the ______, we can quantify the amount of ST elevation and depression. As a rule, changes greater than _____– or less than _________ are significant.
J point; +1.0 or less than -1.0
Hypokalemia causes an
increased PR interval, increased QT interval, T wave flattening and a U wave
Hyperkalemia causes
peaked T waves, P wave flattening, PR prolongation, QRS prolongation, sine wave pattern, and ventricular fibrillation
Hypercalcemia is associated with
a short QT interval
Hypocalcemia is associated with a
long QT interval
Hypermagnesemia is associated with
heart block and cardiac arrest
Hypomagnesemia is associated with a
long QT interval (risk of torsades de points)
T wave points in opposite direction of QRS if repolarization is prolonged by
myocardial ischemia
bundle branch block
This may occur with hypothermia
Osborn wave- small positive deflection immediately after the QRS complex
Duration of the P wave is
0.08-0.12
Duration of the PR interval is
0.12-0.20
Duration of the Q wave is
<0.04
Duration of the QRS complex is
<0.10
Duration of the QTC interval is
<0.47
The ____________ is the average current flow of all action potentials at a given point in time
The mean electrical vector
A positive deflection in the EKG occurs when the vector of depolarization travels
towards positive electrode
A negative deflection in the EKG occurs when the vector of depolarization travels
away from a positive electrode
___________________ on the EKG occurs when the vector of depolarization travels perpendicular to a positive electrode
A biphasic deflection
The bipolar leads include
I, II, III
The limb leads include
aVR, aVL, aVF
The precordial leads include
V1-V6
Inferior heart leads include
II, III, aVF
Inferior heart leads correspond to the
right coronary artery
Left lateral heart leads include
I, aVL, V5, V6
Left lateral heart leads correspond to the
circumflex artery
Anterior heart leads include
V1-V4
Anterior heart leads correspond to the
left coronary artery
