Dysrhythmias Flashcards
Disturbance in the electrical activity of the heart
dysrhythmia
ECG p-wave represents
Atrial depolarization (atrial kick)
Atrial kick represents what percent of cardiac output
20-30%
QRS Complex represents
Ventricular depolarization
T-Wave represents
Ventricular repolarization
Isoelectric line indicates
No muscular activity in the heart (flat line between waves and complexes)
Normal conduction of the heart originates in the
SA node
A 12-lead ECG shows ___ views of the heart
12
Why is a 12-lead ECG beneficial?
It gives a better idea of where the blockage may be
A 5-Lead ECG shows ___ views of the heart
7
Most typical ECG used
5-lead; 12-lead for MI
Spread of impulse from atria to Purkinje fibers (p-wave to beg QRS complex)
PR Interval
Normal PR Interval measurement
0.12-0.20 sec
Time it takes for depolarization of both ventricles
QRS interval
Normal QRS Interval Measurement
0.04-0.11 sec
Time it takes for complete depolarization and repolarization of the ventricles
QT Interval
Normal QT Interval measurement value
0.34 - 0.43 seconds
What is important to know about the T-Wave
Very fragile; messing w/ T-Wave can lead to fatal dysrhythmia
Steps to interpret ECG
- Evaluate HR - #QRS in 6 sec x 10 = HR
- Is rhythm regular? - distance between QRS same?
- P-wave before every QRS?
- T- Waves upright?
- PR and QRS intervals - measure them. Are they normal?
What happens if there is no P-Wave?
no atrial kick; loss of 20-30% cardiac output
Number 1 priority for treating dysrhythmias
TREAT THE PATIENT AND NOT THE MONITOR/DYSRHYTHMIA
Treatment of dysrhythmias are based on
Hemodynamic status of the patient ( color, BP, HR, Pain)
Symptomatic Sinus Bradycardia
Pale, cool, decreased BP, dizziness
Sinus Brady Treatment
Treat only if symptomatic
Atropine IV push (drug of choice)
Pacemaker for extreme cases
PR interval greater than 0.20 seconds
First Degree AV Block
Failure to capture with a permanent pace maker is the result of
Insufficient charge to the myocardium
Failure to capture is bad because
It can lead to serious bradycardia or asystole
Sinus Tachycardia manifestation and s/s
HR = 101-200 BPM
Potential decrease in CO r/t inadequate vent. Filling time
(Dizziness, low BP, SOA, chest pain)
Treatment for Sinus Tachy
Treat underlying cause - pain meds, acetaminophen for fever, beta blockers might be started
Where does impulse originate in PACs
Ectopic source in atrium (other than SA node)
What does PAC look like?
Distorted p-wave before PAC; Usually have normal conduction through the ventricles
What can cause PACs
Caffeine, stress, exercise, tobacco, electrolyte imbalance, heart disease, hypoxia
Symptoms of PACs
Usually palpitations
Healthy patients = asymptomatic
PAC Treatment
Treat Underlying source (caffeine, smoking, stress. . .)
Can be warning of more serious dysrhythmia in pts w/ heart disease
Supraventricular Tachycardia (SVT) impulse origination
Ectopic focus above the bundle of His
SVT manifestations
HR > 150 BPM
Often triggered by PAC
Treatment of SVT
- Vagal Stimulation
- Drug Therapy
- Cardioversion, if pt is unstable
- Ablation if recurrent
Drug Therapy for SVT
IV Adenosine
IV Beta blockers and Calcium Channel blockers
Biggest difference between atrial flutter and atrial fibrillation
Atrial flutter impulse = single ectopic focus in atria
Atrial fibrillation impulse = multiple ectopic foci
Characteristic of atrial flutter on ECG
Saw-tooth shaped flutter waves
Seen in patents w/ heart and lung disease
Atrial flutter manifestation
Atrial rate can be 200-350 BPM
Atrial Fibrillation manifestation
Atrial rate = 350-600 BPM
Ventricular rate = 60-100 (controlled)/ >100 (rapid ventricular response or RVR)
Goals for treatment of A-Flutter/A-fib
HR Control
Rhythm Control
Rate control (A-flutter/fib)
Goal: achieve HR 60-100 BPM
Use: beta blockers, calcium channel blockers, digoxin
Rhythm Control (A-flutter/fib)
Goal: Convert back to sinus rhythm
Use: Amiodarone or Sotalol
Delivery of “timed” electrical current to stop a tachydysrhythmia
Cardioversion
Cardioversion is used for
Unstable atrial dysrhythmias and unstable v-tach w/ pulse
What is the main thing to remember with cardioversion
Sync button ( to sync to heart beat and avoid cardioversion on t-wave)
Nursing Care: Pre-Cardioversion
Warfarin therapy for planned (3-4 weeks before) IV Sedation Consent NPO Oxygen
Nursing Care: Post-Cardioversion
Watch Airway
Check Gag reflex (if TEE was done and throat numbed)
ECG and V/S
Watch for decreased Cardiac output
Premature ventricular contractions
Impulse origination
Originates in ventricles (ectopic focus)
What does PVC look like on ECG
Premature QRS (will be wide and look different than other QRSs)
What is the problem w/ PVCs?
Can lead to v-tach
Things that can cause PVCs
Caffeine, low potassium, low magnesium, fever, exercise, coronary artery disease, MI
Treatment for PVCs
IF frequent and pt is unstable: meds - amiodarone; beta blockers
Correct any problems: electrolyte replacement, decrease caffiene intake
Ventricular tachycardia (v-tach) is
A run of 3 or more PVCs
Ventricle takes control as the pacemaker
Life threatening
Ventricular rate of v-tach and consequences
> 100 BPM = decreased vent filling time = decreased CO
V-Tach Treatment
W/ Pulse: Meds (amiodarone = antiarhythmetic; sotalol to maint sinus rhythm; cardioversion if unstable)
W/O Pulse: Call Code and begin CPR and rapid defibrillation
Ventricular Fibrillation (v-fib) Impulse origination
Multiple ectopic foci w/in ventricles
What is v-fib
Quivering of ventricles; no real heart activity;
LETHAL CARDIAC ARREST- loss of consciousness w/in seconds and death w/in minutes
Treatment for v-fib
Call a code
Immediate CPR and Defibrillation
Drug therapy and ACLS
Defibrillation is the treatment of choice to stop
V-fib and pulseless v-tach
Timeframe for defibrillation
Critical w/in 2 minutes max
Speed is essential: >12 minutes = < 5% survival; <1 min = 90% survival
What should you charge defibrillator to?
360J for monophonic defibrillators
Implantable Cardioverter-Defibrillator (ICD) is used for
Patients who have spontaneous sustained v-tach or are at risk for life threatening dysrhythmias
How much of a shock does ICD deliver
25J after sensing a lethal rhythm (goes directly into heart)
Nursing Care: Pacemaker and ICD: Pre-procedure
NPO night before
Consent
Possible antibiotics
Nursing Care: PPM and ICD: Post-Procedure
ECG Monitor for stable rhythm; Chest x-ray to check lead placement; Immobilize arm first 24 hrs; Incision care - no drainage; activity restrictions; education (patient)
