Exam 3 Flashcards
SA node inherent rate
60-100
AV node inherent rate
40-60
AV node location
in the wall between the right atrium and right ventricles
AV node relays impulses from ___ to ____
SA node to ventricles
Four main cardiac cycle electrical events
cardiac action potential
depolarization
repolarization
refractory period
contraction of the heart
depolarization; systole
during depolarization, __ flows into cell __ flows out
Na; K
resting state of the heart
repolarization; diastole
EKG: Positive Deflection
impulse moving towards lead
EKG: Negative Deflection
impulse moving away from lead
P wave=
atrial depolarization
QRS complex=
ventricular depolarization
T wave=
ventricular repolarization (most sensitive time)
U Wave=
final phase of repolarization
PR Interval #
0.12-0.20; measure at the beginning of Q
PR Interval measures from ___ to ___
beginning of P to beginning of QRS
QRS Interval #
0.06-0.12
QRS interval measured from ___ to ___
beginning of the Q to the end of the S wave
QT measure from __ to ___
beginning of QRS to end of T wave
QT interval #
0.32-0.40
Total time from ventricular depolarization to repolarization
QT interval
Rule of 10
irregular rhythm; count number of R waves in a 6 second strip
Rule of 1500 or 300
regular rhythm; count small boxes between R waves
Atrial Dysrhythmias
PAC- premature atrial contraction
PAT/SVT- Paroxysmal Atrial Tachycardia/ Supraventricular Tachycardia
A Flutter-
A Fib
Key points of atrial dysrhythmias
-originate from foci within atria, not SA node
-different or variable P waves
-NORMAL QRS complexes
Rhythm: a single beat that occurs when an electrical impulse starts in the atrium before next normal SA node impulse
Waves: P wave is early, differs in size and shape, PR interval will be shortened
Premature Atrial Contractions (PAC)
Controlled A FIb
<100 with ventricular bpm
uncontrolled A fib
rate >100 ventricular bpm
Atrial rate is 300-600 per minute and ventricular can be up to 120-200 bpm
no p waves, no measurable PR interval; normal QRS, ventricular rate is irregular and varied
A fib
Treatment for A-fib
rate and rhythm control
antithrombotic- aspirin
rate control- beta blockers
rhythm control- amiodarone
causes: cardiac or pulmonary diseases, digoxin toxicity, PE
rate: rapid atrial rate (250-400)
rhythm: sawtooth pattern
waves: normal QRS, no p wave, no pr interval
A-flutter
pacemaker of the heart
SA node
Bundle of His
Junctional Fibers
Purkinjie Fibers
inherent rate #
14-20 ventricular contractions; no atrial contractions; not life supporting
do you see atrial repolarization on the rhythm strip?
no, only ventricular
Relative refractory period
most of T wave,
can be depolarized with a strong stimulus
can cause R on T phenomenon
Absolute refractory period
most of QRS complex
cardiac cells can not be stimulated to depolarize
1 little box on EKG strip =
0.04 seconds
1 big box on EKG strip=
0.20 seconds
To analyze rhythm strip, you always need a ___ second strip
6
P-P interval measures
atrial rate and rhythm; measure from the beginning of the p wave
To interpret rhythm, measure
Regular or Irr [p-p r-r
PR (0.12-0.20)
QRS (0.06-0.12)
QT (0.32-0.40)
ST segment info
-early ventricular repolarization
-end of QRS complex to start of T wave
-should be isoelectric
sinus arrhythmia: everything is regular except ___
rhythm
Sinus: if interruption lasts <3 seconds =
sinus pause
P wave that came too soon
PAC
SInus: if interruption lasts >3 seconds =
sinus arrest
Premature Atrial Contraction (PAC) causes
caffeine, alcohol, hypokalemia, pregnancy, atrial MI, and w/tachycardia
A Fib causes
-heart valve disorders, cardiomyopathy, MI, COPD/lung diseases, CHF, pericarditis
Causes loss of atrial kick (decreased CO by 30%)
A fib
Paroxysmal Afib
its transient, comes and goes
possible treatment for A flutter
adenosine
Junctional Rhythms originate within the ___ ___
AV node
Junctional Rhythm HR
40-60 bpm
Accelerated Junctional Rhythm HR
> 60-100 bpm
Junctional Tachycardia HR
> 100 bpm
-occurs when irritable site within AV node fires impulse before SA node fire
-impulse interrupts sinus rhythm
-narrow QRS, absent or unidentifiable P wave
-just monitor
Premature Junctional Complexes (PJC)
Junctional rhythm causes
-digoxin toxicity
-Av node ischemia
-isoproterenol infusion
Rhythm: AV node is pacemaker
Waves: P wave may occur just before QRS, during QRS, or not at all
Narrow QRS with normal QRS intervals
Junctional Rhythm
If person with Junctional Rhythm is symptomatic, treat like
bradycardia
with junctional rhythm, patient loses ___
atrial kick
SA-AV-SA-AV
AVNRT-SVT-Paroxysmal Atrial Tachycardia
AVNRT-SVT-Paroxysmal Atrial Tachycardia causes
caffeine, nicotine, hypoxemia, stress, CAD, cardiomyopathy
rate: 151-250
rhythm: an impulse that is re-routed repeatedly back to the same area
waves: P waves are difficult to see hidden T waves from previous beat
Normal QRS
AVNRT-SVT-Paroxysmal Atrial Tachycardia
Symptoms of unstable patient with AVNRT-SVT-Paroxysmal Atrial Tachycardia
decreased CO, decreased BP, decreased urine output
cold/clammy skin, dizziness, decreased LOC
treatment for stable AVNRT-SVT-Paroxysmal Atrial Tachycardia
vagal maneuvers, adenosine, CCB, BB
treatment for unstable AVNRT-SVT-Paroxysmal Atrial Tachycardia
Vagal maneuvers, synchronized cardioversion
ventricular dysrhythmias
-Premature Ventricular contraction
-Idioventricular rhythm
-Polymorphic VT/ Torsades de Pointe
-VFib
-Agonal
-Asystole/Ventricular standstill
Premature Ventricular Contraction (PVC) causes
electrolytes (hypokalemia), MI, acidosis, dig toxicity
Rate: variable
Rhythm: irregular
waves: no p waves, QRS complex is wide and bizarre,
types: multifocal, bigeminy (every other beat), trigeminy (every third beat), couplets, salvo, runs of VT (>4 or more), concerned with 6/min…uni (one type of deflection) vs multifocal (different deflections)
PVC
increased PVC is warning sign for
Ventricular tachycardia (V tach)
Rate: >100 bpm
Rhythm: regular rhythm, monomorphic
Waves: no P-waves, wide QRS complex, T wave opposite QRS
V Tach
V Tach causes
myocardial irritability, R on T phenomenon, ACS/MI, ischemia, prolonged QT(i), heart failure, CMO, electrolyte imbalance,
V Tach treatment
Pulse: RRT, amiodarone, procainamide, lidocaine, cardioversion,
No pulse: CPR, defib
Polymorphic VT/ Torsades de Pointes causes
hypomagnesemia,
meds: Cipro, methadone, haloperidol, erythromycin,
Waves: No p-waves, associated with prolonged QT(i), Mg+ levels, and meds
Rhythm: twisting of the points
rate: >100 bpm
Polymorphic VT (Torsades de Pointes)
___ = D fib
V fib
Rate: >100 bpm
Rhythm: fine or coarse, rapid chaotic irregular rhythm, no organized
Waves: no measurable P waves, PR intervals, no measurable QRS complexes, ST or T waves
no CO= clinical death
Ventricular Fibrillation (V Fib)
Rate: 20-40 (from ventricles)
Rhythm: usually regular, SA/AV node not initiating, beat coming from Bundle of HIS or Perkinje fibers
Waves: no p waves, wide abnormal QRS
Idioventricular- Ventricular Escape Rhythm
Causes: End of Life, multi-system organ failure,
rate: <20 bpm
rhythm: irregular
waves: no p waves, QRS extremely wide and slurred, often not treated
Agonal Rhythm
Rate: <20 bpm
Rhythm: no electrical activity, requires 2 lead confirmation
waves: standstill, only p waves noted
Ventricular standstill/ Asystole
PEA is treated like___
asystole
PEA & Asystole are shockable rhythms: true or false
false
Conduction abnormalities
heart blocks:
-1st degree
-2nd degree type 1 (wenchebach)
2nd degree type 2
3rd degree (complete Hb)
Conduction abnormalities facts
hemodynamics worse as degree worsens
causes: lyme disease , dig toxicity, CCB, MI and ischemia
R coronary artery feeds blood to the
SA node
Rate: regular, atrial impulse is slower than normal
Rhythm: regular
waves: P wave normal size, shape, QRS- normal, PR(i) CONSISTENTLY PROLONGED >0.20 seconds and the same for all
First Degree AV Heart Block
2nd degree HB type 1 [wenchebach] treatment for asymptomatic
no treatment
2nd Degree HB type 1 [wenchebach] symptomatic treatment
atropine
Rate: Regular
Rhythm: atrial regular, ventricular irregular, patterned 1 beat loss,
Waves: p waves present but all conducted, PR (i) lengthens until one is not conducted, QRS normal, but periodically dropped, sa/av node not carrying consistently
2nd degree HB type 1 [wenchebach]
Rate: atrial rate regular, ventricular rate slower than atrial,
rhythm: atrial regular, ventricular rhythm irregular, patterned 1 beat loss,
Waves: p waves normal, but not all conducted, PR(i) is normal or prolonged all PR(i) are the same, THERE is NO LENGTHENING of PR(i)
waves: QRS normal, but occasionally dropped
2nd degree HB type 2 (mobitz II)
2nd Degree HB Type II (Mobitz II) treatment
temp pacemaker
AVOID ATROPINE
Lethal Rhythms
V FIb
V tach
3rd degree AV Block (complete HB)
idioventricular
asystole
PEA
Rate: A and V rate regular but not the same (no association)
Rhythm: A rate faster than V rate and are regular. 2 independent rhythms @ same time
waves: P waves present but have no relationship w/ QRS complex, P waves march on, PR(i) not measurable, QRS wide or narrow
3rd Degree HB (complete HB)
There are 2 independent rhythms happening at the same time
3rd degree HB
3rd degree HB treatment
AVOID atropine, pacemaker at bedside