NURS 444 week 6 arrhythmias Flashcards
Properties Cardiac Cells
Automaticity- ability to initiate impulse
Excitability- ability to be electrically stimulated
Conductivity- ability to transmit an impulse in an orderly manner
Contractility- ability to respond mechanically
U wave
if present;
repolarization of purkinje fibers OR hypokalemia
Normal QRS interval in seconds
What rhythms can be defibrillated
v fib
pulseless v taach
v tach
1mm square
0.04 sec
5mm box
0.2 seconds
Sinus Bradycardiaa
SA nodes fires less than 60 seconds
Can be sleeping or from an athlete
Associated with some disease states
Can occur with response to parasympathetic nerve stimulation and certain drugs
Sinus Bradycardia:
Clinical associations
Occurs in response to;
-Carotid sinus massage
-hypothermia
-increased vagal tone
-meds.
Occurs in disease states;
>hypothyroidism
> ^ intracranial pressure
>obstructive jaundice
>inferior wall MI
Sinus Tachycardia
- Discharge rate from SA node is increased (>100 bpm)
- caused by vagal inhibition or sympathetic stimulation
- physiologic or psychological stressors
- drugs can increase rate
Sinus Tachycardia: Clinical associations
_ exercise
_ hypotension
_ hypovolemia
_ myocardial ischemia
_ CHF
_ anxiety
normal PR interval
0.12 (3 boxes) - 0.2 (5 boxes)
- if it’s longer it may be a block
- if it’s shorter it is called a junctional rhythm
Normal QRS interval
< 0.12
- if greater, you can have a disturbance in the ventricles (block)
Elevated ST segment
What does a depressed ST segment mean?
unusual T wave?
Premature Atrial Contractions
- contraction starts from ectopic focus in the atrium
- travels across the atria by abnormal pathway –> distorted P wave
- impulse may be stopped or delayed
PAC: clinical associations
> emotional stress
physical fatigue
caffeine
tobacco
alcohol
hypoxia **
electrolyte imbalances
disease states: infection, inflammation, COPD, valvular disease **
Paroxysmal Supraventricular Tachycardia (PSVT)
Starts or stops abruptly
- originated in ectopic focus anywhere above bundle of HIS (QRS interval is normal, less than 3 boxes) **
-paroxysmal means an abrupt onset and termination
- usually a PAC triggers a run of repeated premature beats **
PSVT: clinical associations
- overexertion
- stress
- deep inspiration
- stimulants, disease
- digitalis toxicity
- can occur in presence of Wolff- Parkinson- White Syndrome (onset during childhood)
Atrial Flutter
^ atrial tachyarrhythmia
^ identified by recurring, regular, sawtoothed-shaped waves
^ from single ectopic focus
^ associated with slower ventricular response. (ex. atrial rate 200-350, vent. rate generally <100
^ vent. rate may be regular or irregular
Atrial fibrillation
total disorganization of atrial activity w/out effective atrial activity
chronic or intermittent; Paroxysmal or Persistent
most common dysrhythmia
prevalence increases with age
usually occur with underlying heart diseases
atrial rate 350 -600, ventricular response variable/ irregular (CVR 60-100, rapid ventricular response RVR)
A. flutter: clinical associations
- CAD
- htn
- mitral valve disorders
- cardiomyopathy
- pulmonary embolus
- chronic lung disease
- Cor pulmonale
- hyperthyroidism
- Drugs: digoxin, quinidine, epinephrine
A. fib: clinical association
> CAD or cardiac surgery
htn
valvular heart disease
cardiomyopathy and/or HF
pericarditis
thyrotoxicosis
alcohol intoxication and/or caffeine
electrolyte imbalances
stress
First Degree AV block
PR interval prolonged (> .20)
Associated with increasing age, disease states, and certain drugs
usually not serious; patients asymptomatic
no treatment
monitor for changes in heart rhythm
2nd Degree AV block, Type 1 (mobitz 1, Wenckebach)
“type 1- wencke- widen”
- gradual lengthening of PR interval until QRS complex eventually dropped.
— occurs because of prolonged conduction time
may result from drugs or CAD
typically associated with ischemia
usually transient and well tolerated
TREAT if symptomatic with; Atropine or pacemaker ***
observe closely if symptomatic- give atropine
can progress into more serious
have pacemaker, code cart on stand by
MOST DANGEROUS TIME FOR A.FIB
when they go down to cardioversion AND they are NOT anticoagulated
Second Degree AV block Type 2
Sudden dropped QRS complexes
-no widening of PR interval
- P wave not conducted
- almost always occurs when bundle branch block is present
- associated with heart disease and drug toxicity
- unlike type 1, we drop the beat without warning (PR intervals are the same)
Third Degree AV Heart Block
“Complete Heart Block”
- P waves & QRS complexes have nothing to do with each other. “divorced”
- no impulses from atria conducted ventricles
- no/ minimal CO
Associated with;
- severe heart disease; CAD, MI, myocarditis, cardiomyopathy, scleroderma
- some systemic diseases
- certain drugs; digoxin, beta blockers, calcium channel blockers
DO NOT GIVE ATROPINE!!!***
PVCs
contraction that originates somewhere in the ventricles
- premature QRS occurrence
- can be unifocal (look the same) or multifocal (look different)
- QRS complex is widened: wider than 0.12
PVCs: clinical associations
stimulants, electrolyte imbalances, hypokalemia hypoxia, heart disease, exercise
may occur following acute MI and/or following coronary artery reperfusion, mitral valve prolapse
R-on-T
if PVC happens during T…
ventricular tachycardia can occur
Ventricular Tachycardia
- Run of 3 or more PVCs
occurs - ectopic foci in ventricles take over as pacemaker
- monomorphic, polymorphic, sustained and nonsustained
V-Tach: clinical associations
- Heart disease
- long QT syndrome
- electrolyte imbalances
- drug toxicity
- CNS disorders
- has been observed in individuals with no evidence of heart disease
Ventricular Fibrillation
chaotic firing of multiple ectopic Vent. foci
V. Fib: clinical associations
- Acute MI
- electrolyte imbalances, hypoxia, acidosis
- chronic disease (CAD, HF, cardiomyopathy)
- cardiac procedures
- electrical shock
- drug toxicity
Pulseless Electrical Activity
- activity can be observed on the ECG, but no mechanical activity of the heart is evident
- patient has no pulse
- prognosis is poor unless cause is identified and treated
PEA: causes
> hypovolemia
hypoxia
hydrogen ion (acidosis)
hyper/ hypokalemia
hypoglycemia
hypothermia
toxins
tamponade (cardiac)
thrombosis (MI and pulmonary)
tension pneuomo.
trauma
PEA: treatment
- CPR, intubation, IV epinephrine
- treatment directed to underlying cause
Defibrillation
treatment of choice for V.FIB and pulseless VT
Synchronized Cardioversion
treatment of choice for ventricular or supraventricular tachydysrhythmias (VT with pulse)
synchronized delivery of a shock on the R wave of QRS complex of ECG
intent is to allow SA node to resume role
ICD: implantable cardioverter defibrillator
- for patients who survived sudden cardiac death
- have spontaneous sustained VT
- have syncope w/ inducible ventricular tachycardia/ fibrillation during EPS
- who are at high risk for threatening dysrhythmias
