ECG Flashcards
ECG
Sa node fires and stimulates atrial contraction
normal duration - 0.06-0.12
P wave
Beginning of P wave to beginning of QRS complex
time taken for impulse to spread from SA node to purkinje fibers
immediately preceding ventricular contraction
normal duration - 0.12 - 0.20
PR Interval
Beginning to end of QRS complex
represent depolarization(contraction) of both ventricles (systole)
normal duration - < 0.12 (3 small squares)
QRS Complex(interval)
Measured from S wave to beginning of T wave
represents time between ventricular depolarization and depolarization (diastole)
normal duration - 0.12
ST segment
time for ventricular repolarization (resting phase)
normal interval - 0.16
T wave
from beginning of QRS complex to end of T wave
represents time taken for entire depolarization and depolarization of ventricles
Normal duration - 0.34-0.43
QT interval
rhythm that initiates in SA node at rate of 60-100 times per min.
follow normal conduction pattern of cardiac cycle.
Normal Sinus rhythm
secondary pacemaker at the rate of 40-60 times per min. delay allows for atrial contraction and filling of ventricles. Not considered lethal.
Atrial dysrhythmia - Originates at AV node
secondary pacemaker at the rate of 20-40 times per minute.
Ventricular Rhythm - Originates at His-Purkinje system. - carry electrical impulse directly to ventricles
1 rule of ECG
Check the patient. How are they tolerating rhythm, S/S, Lethal dysrhythmia?
reversal of charges at the cell membrane when the cells are stimulated that allow sodium to flow into the cell making the inside of the cell positive.
depolarization
restoration of the polarized state at a cell membrane making the inside of the cell negative
repolarization
Ability to initiate an impulse spontaneously and continuously
automaticity
ability to be electrically stimulated
excitability
Ability to transmit an impulse along a membrane in an orderly manner
conductivity
Ability to respond mechanically to an impulse
contractility
One complete contraction and relaxation cycle of the heart.
cardiac cycle
Pulse < 60. PR interval normal, QRS for Each P wave
Sinus Bradycardia
Pulse 100-200. PR interval normal. QRS for each P wave
Sinus Tachycardia
Information obtainable from ECG
HR, Rhythm/regularity, Impulse conduction intervals, abnormal conduction pathways
a printed record of electrical activity that defines the graphic representation of the electrical activity of the heart
the ECG (Electrocardiogram)
5 steps to ECG strip interpretation
- HR
- Heart Rhythm
- P-wave
- PRI
- QRS Complex
Step 1 - HR
Six second strip count R wave multiple by 10.
Step 2 - Heart Rhythm
Regular or Irregular?
Established pattern between QRS complexes?
Measure ventricular rhythm between r-r
Measure atria rhythm between p-p
Step 3 - P-wave
Are they present?
Do they occur regularly?
Is there a P for each QRS?
Do they all look similar?
Step 4 - PR Interval
Normal - 0.12-0.20 (3-5 small boxes)
Are they < or >?
Are they consistent?
Step 5 - QRS Complex
Are they narrow (< 0.12)?
Are they wide (>0.12)?
Are they similar across strip
Steps for emergency management
1- ensure ABCs 2 - Administer O2 via nasal canula or non-rebreather mask 3 - Obtain baseline vitals 4 - Obtain ECG 5 - Initiate continuous ECG monitoring 6 - Identify underlying rate and rhythm 7 - Identify dysrhythmia 8 - Establish IV access
S/S Sinus Bradycardia
pale,cool skin, hypotension, weakness, angina, dizziness, syncope, confusion, SOB
TX Sinus Bradycardia
Administer atropine, possible pacemaker therapy, Hold drugs or reduce dosage if they are the cause.
S/S Sinus Tachycardia
Dizziness, dyspnea, hypotension due to decreased cardiac output. Increased myocardial O2 consumption associaed with increased HR. Angina or increased MI
TX Sinus Tachycardia
treat underlying cause. (pain, hypovolemia) also IV beta blockers may reduce HR and O2 consumption.
Premature atrial contraction (PAC)
Atrial contraction originating from somewhere other than SA Node. created a distorted P wave.
PAC clinical causes
may result from emotional stress, physical fatigue, caffeine, tobacco, alcohol. Also hypoxia, electrolyte imbalance, COPD, hyperthyroidism, heart disease.
Atrial Flutter
atrial tachydysrhythmia identified by recurring regular sawtooth shaped flutter waves that originate mostly from rt atrium.
Atrial Fibrillation
total disorganization of atrial electro activity. Most common clinically significant dysrhythmia. Pwaves are replaced by chaotic fibrillatory wave (350-600 per min). results in decreased CO because of ineffective atrial contraction. Cause for 20% of strokes.
SA or AV node fails to initiate impulse. Ventricle pace heart
ventricular rhythms
Premature QRS complex that is wide and distorted in shape. Associated with stimulants (caffeine, alcohol, nicotine,epinephrine)
Premature Ventricular Contraction (PVC)
Three or more consecutive PVCs. May or may not have pulse.
Associated with MI, CAD, electrolyte imbalance, cardiomyopathy, mitral valve prolapse. Also can be seen with no cardiac disease.
Ventricular Tachycardia
MI, mitral valve prolapse, HF, CAD
Disease states associated with PVCs
TX PVC
relates to cause. (O2, electrolyte replacement), Drugs - Beta adrenergic blockers ( procainamide, lidocaine)
ventricles fire with no order or rhythm. No pulse. Lethal rhythm. ventricles quiver with no effective contraction. Start CPR and defib immediately.
Ventricular fibrillation
Most common lethal rhythm with electrolyte imbalance (usually magnesium). Has prolonged QT intervals.
torsades de pointes
No ventricular activity. patient is unresponsive, pulseless, apneic. Patient usually has end stage cardiac disease.
Asystole
electrical activity on ECK but patient has no pulse. Most common causes hypovolemia, hypoxia, metabolic acidosis, hyper/hypokalemia, hypothermia, drug overdose, MI. TX is CPR and drug therapy (epinephrine)
Pulseless Electrical Activity(PEA)
Block of electrical impulse. PR interval is very important.
heart block
Normal HR and rhythm, normal P wave. Prolonged PRI. normal QRS. patient is asymptomatic.
1st degree heart block
Gradual lengthening of PRI. occurs because of prolonged AV conduction time until atrial impulse is non-conducted and QRS is missing
2nd degree heart block (Mobitz type I or wenckebach)
P wave non-conducted without lengthening PRI. heartbeats get dropped. will need pacemaker
2nd degree heart block (Mobitz type II )
No impulses from atria are conducted to ventricles. No communication between atria and ventricles. They work independently.
3rd degree heart block ( complete)
common causes of Dysrhythmias
accessory pathways, cardiomyopathy, conduction defects, heart failure, myocardial cell degeneration, MI, valve disease
Other causes of Dysrhythmias
acid-base imbalance, alcohol, caffeine, tobacco, drug effects, electric shock, hypoxia, poisoning, near drowning
S/S of dysrhythmias
Change BP, Dec O2 sat, chest/neck/shoulder/back/jaw/arm pain, dizziness, syncope, dyspnea, diaphoresis, pallor, N&V, anxiety restlessness, DEC LOC/confusion, feeling impending doom, numbness/tingling arms, weakness, fatigue, cold clammy skin, palpitations
Dysrhythmias treatments
Med review, Synchronized cardioversion, Ablation therapy, pacemakers, defibrillation
check pt, sychronized cardioversion, digitalis, diltiazem, heparin/coumadin, ablation
Atrial flutter tx
check pt, check leads, risk of clots, digitalis, amiodarone, procainamide, syn cardio, ablation
Atrial fibrillation tx
Ask patient to bear down/cough hard
valsalva maneuver - (for SVT)
Care of pt with AICD
dressing- sutures in place, oozing from site, infection, keep left arm down below shoulder, ID card
Pacemakers
Implantable, temporary, atrial or ventricular, set of low and high HR
Blurred vision, green/yellow halos, bradycardia, anorexia, monitor electrolytes
Digoxin toxicity
