Dysrhythmias Flashcards
SA node functions
Electrical impulses stimulates and paces heart at a rate of 60-100bpm, impulse travels into atria. Also known as the pacemaker of the heart.
AV node functions
Muscle cells of the atria contract is known as conduction. AV node has a rate of 40-60; AV node slows impulse allowing time for atria to contract and the ventricles time to feel. backup mechanism of the heart.
Bundle of HIS functions
next place the electrical impulse occurs, from bundle of his; impulse travels to the R and L bundle branches of the Perkinje fibers in the ventricles, this allows the ventricles to contract.
What is systole?
electrical stiulation of the muscle cells of the ventricles in turn cause muscle contraction
What is diastole?
once cells repolarize and ventricles relax, this is diastole.
What does the P wave represent?
conduction through the atrium (depolarization)
What does the PR Interval represent?
Impulse time from SA node through AV node
What does the QRS complex represent?
conduction through the ventricles. (ventricular depolarization)
What does the T wave represent?
ventricular repolarization
What does the QT interval represent?
time from ventricular depolarization through repolarization
what does the ST segment represent?
Early repolarization
what does an elevated ST segment show?
evidence of an acute MI
what does a small box represent?
0.04 seconds
what does a large box represent?
0.20 seconds
how many boxes equal one full second?
5 large boxes
how long should an effective strip be?
6 seconds
How many boxes in 6 seconds?
30 large boxes
What is positive deflection?
waveforms that move up the paper
what should you ask yourself when you look at a strip?
- What is the rate? (Fast or slow) (atrial or ventricular) (Relationship between them)
- Is the rhythm regular? (P to P interval equal time? )
- Is the R to R interval the same?
- Is there a P wave present? (are they upright?) (Is there one or more for each QRS) (Do they have the same appearance?)
- Is the PR interval normal?
- Is the QRS normal or wide?
- ST Segment location? (Isoelectric, Depressed, Elevated?)
- What else? (Symptomatic? Life threatening? New onset or chronic?)
What should a normal P wave look like?
should not exceed 1 box in length
What should a normal QRS look like?
0.08 - 0.12 seconds OR 2-3 horizontal boxes
What should a normal ST segment look like?
should be at the ISOELECTRIC line
Should begin at the end of the S wave and end at the beginning of the T wave.
what should a normal PR interval look Like?
0.12-2.0 Seconds or 3-5 horizontal boxes
What is the 1500 method?
a method of counting the HR on a strip
Count the number of small boxes between two R waves, then divide by 1500
BETTER FOR FAST HR
What is the 6 second method?
A method of counting rate:
Get 6 seconds of an EKG, count the number of R waves in the 6 second period and multiply by 10
BETTER FOR SLOW OR IRREGULAR RHYTHMS
What is normal sinus rhythm?
Sinus node fires 60-100BPM P to P interval is the same R to R interval is the same PR and QRS interval is normal follows an even conduction pattern
With NSR beats will continue to be _______ without changes
regular
In NSR the rhythm will stay the same on _______ or ______________ movement
inspiration
non strenuous
NSR rate can range anywhere from _______ BPM
60-100
what is the treatment for NSR?
continue to monitor.
NEVER DO NOTHING
Criteria for SInus Bradycardia?
Sinus node fires less the 60 BPM
all components of the EKG are present ( P QRS and T)
What kind of heart is sinus brady found in?
Can be in a normal or a diseased heart
Ex. Athletes will naturally have a slower HR
Presentation with Sinus brady?
decreased cardiac output
when do you treat sinus brady?
if the patient is symptomatic
symptoms of sinus brady?
Weakness, fatigue, decreased UOP, Edema, chest pain, syncope
how do you treat sinus brady if the patient has no symptoms?
YOU DON’T!!!!!!!!!!!!
Only treat if there are symptoms.
Continue to monitor.
what are some clinical symptoms of Sinus Bradycardia?
hypotension, pale and cool skin, weakness, angina, dizziness or syncope, confusion or disorientation, decreased LOC, SOB, diaphoresis.
Why does sinus brady occur?
in response to hypoxia, hypothermia, hypo or hyperkalemia, hypovolemia, vagal stimulation (intubation, suctioning…) Toxins, trauma, Pneumothorax, thrombosis. after being given Digoxin, Beta blockers, verapamil, or diltiazem
what is the drug of choice for symptomatic brady?
Atropine!!!!! 0.5mg IV push
can dose up to 3 mg maximum.
GIVEN AS A QUICK IV PUSH. THIS INCLUDES THE FLUSH TO GET THE REST OF THE MED IN!!!!
what is dopamine?
Second line drug for symptomatic bradycardia, used if atropine is not effective
Dose: 2-10 micrograms/KG/Min infusion
this drug is a Inotrope, which increases cardiac Output, increases BP, and low doses increase UOP.
Does Dopamine in high doses cause increased UOP?
NOOOOOOOOOO!!!!!!!!!
It has an adverse effect in higher doses, causing urinary retention.
when is epinephrine used?
used as an equal alternative to dopamine if atropine is ineffective
Dosage is 2-10 micrograms/minute
Is a pacemaker required for symptomatic bradycardia?
can be if medication is ineffective!
Temporary or Permanent-
Transcutaneous- temporary using the Zoll- set to 60 (very painful) sedate before use.
Transvenous- Central venous access- generally femoral sight! Not temporary
What is sinus tachycardia?
When the hr is above 100BPM
Normal sinus rhythm, just faster.
Sinus tachycardia occurs as a result of __________
overly rapid firing of the SA node
Potential causes of sinus tachycardia
Drugs, Disease, Pain, Fever, excitement, caffeine
What is sinus tachy characterized by?
normal resting heart rate but exaggerated postural sinus tachycardia with or without orthostatic hypotension (compensated)
How is cardiac output effected?
it can cause decreased cardiac output
Clinical symptoms of sinus tach?
heart rate 100-150 regular rhythm P wave : only 1 precedes each QRS Clinical presentation is determined by rate and patient tolerance of rate. Dizziness, hypotension, angina
Potential clinical associations of sinus tach?
exercise, pain, hypovolemia, MI, HF, fever, use of atropine, EPI, Dopamine, caffeine, fear
treatment of sinus tach?
treat the underlying cause:
betablockers- reduce HR and myocardial O2 consumption
Calcium channel blockers: decrease automaticity of SA node
Antipyretics
Analgesics
Examples of beta blockers
metoprolol, Coreg (carvidelol), Labetolol
example of calcium channel blockers?
Verapamil
Example of antipyretics?
acetaminophen
What is sick sinus syndrome?
severe sinus node depression:
results in marked sinus bradycardia, SA block or Sinus arrest: May have heart rhythms that are too fast, too slow, punctuated by long pauses_ CAN BE ALL OF THESE
symptoms of sick sinus syndrome?
bradycardia
fatigue, dizziness, fainting, SOB, chest pains, palpitations
risk factors for developing dysrhythmias?
Electrolyte abnormalities Fluid volume Imbalance Hypoxemia hypo/hyperthermia degeneration in conduction system congenital defects MI Drugs
what is supraventricular tachycardia?
a regular, fast (160-220bpm) that begins and ends suddenly and originates in heart tissue other than that in the ventricles
who is paryoxysmal SVT most common in and when?
young people potentially during vigorous exercise.
signs of SVT
uncomfortable palpitations, decreased cardiac output, hypotension, dyspnea, angina, shortness of breath, chest pain
Treatment of SVT
vagal maneuvers, IV adenosine, verapamil, if all else ails, DC cardioversion
how is adenosine given?
two syringe method; 6mg rapid IV push; followed by immediate 20mL NS bolus to push the remainder of med in.
is it normal for adenosine to stop the heart?
YES
It is normal for there to be a pause noted on the ecg strip, it is resetting the rhythm.
Pts say they feel a thud in their chest
What is a premature atrial contraction?
PAC-
early initiation of a p-wave, may be stopped, delayed, or conducted normally at the AV node
what can cause a PAC?
emotional stress, caffeine, tobacco, alcohol use; hypoxia, drugs, electrolyte imbalance, COPD, valvular disease
treatments of PAC?
goal: slow conduction through the AV node Beta blockers Diltiazem Amiodarone Magnesium reduce or eliminate caffiene
which rhythms electrical impulse travels across the atria by abnormal pathway, creating a distorted pwave?
Premature atrial contraction
What is atrial flutter?
Atrial tachydysrhythmia - recurring, regular saw tooth shaped flutter waves with an atrial rate of 250-300, has a normal QRS with saw tooths between
is a flutter regular or irregular?
can be either: may be conducted in a 1:1, 2:1, 3:1, or 4:1
what is there high risk of with a-flutter?
stroke r/t thrombus formation in atria
causes of aflutter?
CAD, alcoholism, CHF, Pericarditis, hypertension, mitral valvular disorders, PE, chronic lung disease, cardiomyopathy, Hyperthyroid, digoxin or epi usage.
treatment of atrial flutter?
goal is to slow ventricular response by increasing AV block;
Calcium channel blockers, Beta blockers, amiodarone
medication tx of a-flutter?
Beta blockers Diltiazem Propafenone Amiodarone Flecainide Clonidine
Non pharm tx for aflutter?
synchronized cardioversion, or radiofrequency catheter ablation
Atrial fibrillation clinical associations?
CAD, alcoholism, CHF, Pericarditis, hypertension, mitral valvular disorders, PE, chronic lung disease, cardiomyopathy, Hyperthyroid, digoxin or epi usage.
causes of afib?
caffiene use, electrolyte disturbance, heart surgery
result of Afib?
decreased cardiac output r/t ineffective atrial contractions and rapid ventricular response, risk of stroke due to blood stasis
tx of afib?
goal is to decrease ventricular response and prevent stroke
digoxin, beta blockers, calcium channel blockers, heparin, coumadin
