1. Chapter 10 Excitation of the hearth and Cardiac conduction Flashcards
Ch 10 excitation of the heart Ch 11Normal ECG Ch13 Cardiac arrhythmia s: 28
Name the normal impulse conduction pathway
SA Node–> AV Node –> AV bundle –> R&L bundle branches –> Purkinje fibers
Where is there a delay seen in the impulse transmission
AV delay
____ pacemaker is located somewhere other than the SA node and causes an abnormal seq of events as noted on an ECG
ectopic pacemaker
SA node has an intrinsic rate of ___ beats/min
70-80
AV node has an intrinsic rate of ____ beats/ min
40-60
Purkinje fibers have an intrinsic rate of ____ beats/ min
15-40
PS stim comes from (3) factors
Vagus N
AcH
Innervates SA and AV
SP stim comes from (3) factors
NE
incr. rate of conduction
incr. force of contraction
P wave reps ______
atrial depolarization
QRS compex reps_______
ventricular depolarization
T wave reps ______
ventricular repolarization
On an ECG paper what are the units for the vertical reading and horizontal reading
horizontal: sec
Vertical: mV
QT interval represents
ventrical depaolarization and repolarization
from right before the Q dip to after the T hump
before stim the external cells of the M are ___ charged and the internal cells are ___ charged
ext= pos. int= neg
- when it becomes depolarized, Neg charges leak to the outside making it neg
____node triggers cardiac impulse
SA node
aka Sinus node
Bradycardia is HR at _____bpm
<60 bpm
c.c. __________sx: baroreceptors in carotid sinus are super sensitive and mild pressure on neck has baro. reflex
carotid sinus sx
carotid sinus sx _______ in carotid sinus are sensitive and slow down HR
baroreceptors
baroceptor reflex will cause an increase in _____ stim
vagal
tachycardia has a bpm of ____
> 100bpm
Catachycardia is a cause of ____ reflex to increase HR to pump more blood out
SP reflex
c.c. ___ arrhythmia that is influenced by parallel vagus N activity during breathing
Sinus arrhythmia
- characterized by irregular distance btw T wave and P wave
Name (3) abnormal sinus arrhythmias
- sinus bradycardia
- tachycardia
- sinus arrythmia
Name the (4) arrhythmias from block of impulse within conduction pathway
- sinoatrial block
- first degree heart block
- second degree “ “
- third degree block (complete AV block)
c.c._____ the impulse is blocked before it enters the R atria so no P wave present .
sinoatrial block
- AV node becomes pacemaker
- QRS are evient but slow
c.c_____ condition where the AV node becomes the pacemaker. There is no P wave
Sinoatrial block
- QRS are eviedent but slow
_____degree heart block is when the P-R interval is >0.2
First degree heart block
- incomplete heart block bc the signal is delayed rather than totally blocked
c.c.______ causes inflammation of the AV node. This condition can cause first degree heart block
acute rheumatic heart disease
What is a “dropped beat”
absence of a QRS & T wave
c.c.___ when the P-R interval is 0.25-0.45
Second degree heart block.
- some impulses pass through the AV bundle but others do not causing “dropped beats”
c.c.___ block: complete lack of synchronization btw atria and ventricles
complete AV block
- PP interval consistent
- QRS & T is dissociated
c.c.____ block complete AV block
third degree block
c.c ___sx is a complete AV block that comes and goes. Causes fainting
Stokes adams syndrome
tx for stokes adams sx
pacemaker to R ventricle
_______ ventricules excitability is suppressed bc ventricles have been driven at rate greater than natural rhythm (stokes adams sx)
over drive suppression
______: occurs woth an AV node or AV bundle stim (15-40bpm) since there is a block in the SA node
(stokes adams sx)
ventricular escape
premature contractions are a results of ____
ectopic foci
Name (4) causes of ectopic foci
- local areas of ischemia
- irritation of cardiac M
- toxic irritation from drugs, caffeine, or nicotine
- mech initiation of PVC during catheterization of R ventricle
pulse deficit can occur in PACs bc ____do not fill so SV decr.
ventricles
re-entrant pathway occurs when an impulse ___ and results in a self perpetuating impulse formation
loops
- can cause atrial flutter
______: the affected atria contracting at a rate of 200-350 bpm bc of re-entry wave
atrial flutter
- not all ventricles are stim. QRS every few
_____: activation of atria is irregular and CHAOTIC so atria bc useless
atrial fibrillation
- cause: atrial hypertrophy
____: premature contraction originate in one of the jxns
jxn rhythms
- P wave occurs late so it occurs in QRS
- distorts QRS, inverts it
____: P wave travels backward into atria
In Jxn rhythms
retrograde direction
_________: condition where QRS has abnormal form bc one side depolarizes ahead of the other. T wave is inverted
Premature Ventricular contractions (PVCs)
c.c______: ventricules are stim to contract at 120bpm. re-entrant stim leads to circular activation
ventricular tachycardia (V-tach)
- cause by ischemia or myocardial infraction
c.c.______: ventricular depolarization occurs CHAOTICALLY so some parts contract while others are relaxed so little blood pumped out of heart
Ventricular Fibrillation (V-Fib )
