Basic EKG interpretation (1) Flashcards
Sinus Rhythm
Sinus bradycardia
Sinus tachycardia
Junctional Rhythm
Junctional Tachycardia
Supraventricular tachycardia
Premature atrial contraction
Atrial fibrillation
Atrial flutter
Premature ventricular contraction
1st degree AV block
2nd degree type 1 AV block
2nd degree type 2 AV block
3rd degree AV block
Ventricular tachycardia
Ventricular fibrillation
What things would you look at on an EKG to determine if it’s normal?
- PR interval; is it fixed?
- QRS complex; regular, narrow or wide?
- RR intervals
What range would be considered sinus tachycardia?
100 to 150
What is a heart rate of >150 considered?
supraventricular rhythm
What is the rate for a junctional rhythm?
40 to 60
What does an inverted P wave mean?
Retrograde conduction from the normal conduction pathway
What meds could be used for atrial fibrillation?
Why do you want to be careful using them?
- Amiodarone
- Cardizem
- Beta blockers
- Digoxin
- these patients can become bradycardic with these meds
How do the general anesthetics effect the heart?
- Halothane/enflurane - sensitize myocardium
- Norepi reuptake inhibitors - cocaine, ketamine
- Sevoflurane - bradycardia in infants
- Desflurane - prolonged QT during induction
How do local anesthetics effect the heart?
- Severe bradycardia
- Intravascular - asystole; lipid rescue
What are causes of perioperative dysrhythmias?
- General anesthetics
- Local anesthetics
- Abnormal ABG or lytes
- Endotracheal intubation
- Autonomic reflexes during case
- CVP cannulation
- Locale of surgery (oculo-cardiac reflex)
The heart has the innate ability to generate its own spontaneous action potentials without any external stimuli, a phenomenon known as __________.
Automaticity
What are the two types of cardiac cells?
Pacemaker cells and contractile cells
When there is a stimulation above the threshold, __________ channels cause cell-to-cell conduction resulting in depolarization.
This will release ________ to interior myocytes and causes contraction.
_______ outflow causes repolarization.
Sodium channels; calcium; potassium
Once the action potential is generated by the SA node, conduction will go to the right atrium via the __________ pathway.
Conduction will also travel from the right atrium to the left atrium via ____________.
Internodal pathway
Bachman’s bundle
Inherent pace of the SA node:
Inherent pace of the AV node:
60 - 100
40 - 60
How long is the delay at the AV node?
0.1 second
What rate can the pacemaker cells in the bundle branch generate action potentials at?
20-40
What rate can the pacemaker cells in the purkinje fibers generate action potentials at?
20 - 40
How many mV are the large boxes?
How many mV are the small boxes?
How many seconds are the small boxes?
How many seconds are the larges boxes?
0.5 mV
0.1 mV
0.04 seconds
0.20 seconds
What does the P wave represent?
What is a normal duration?
Atrial depolarization; <0.12 seconds
What does the PR interval represent?
What is a normal duration?
AV conduction; 0.10 - 0.20 seconds
What does the QRS complex represent?
What is a normal duration?
Ventricular depolarization
<0.12 seconds
What does the ST segment represent?
Early stages of ventricular repolarization
ST segment elevation/depression > ___ significant
1 mm significant
What does the T wave represent?
Ventricular repolarization
When is atrial repolarization?
a. during PR interval
b. during QRS interval
c. during ST segment
d. during T wave
B. During QRS segment
What are the inherent pacemakers?
SA node, AV node, Ventricular tissue
What is a PR interval greater than 0.2 seconds called?
First degree AV block
What do we associate with a QRS complex wider than 0.12 seconds?
Bundle branch block
What does it mean when we say the heart has automaticity?
The heart has the ability to generate its own action potentials (involuntary)
What are the 2 types of cardiac cells?
Pacer cells (in SA, AV, Bundle of His, L/R bundle branches, and purkinje fibers)
Contractile cells (bulk of myocardium)
What is a big reason to cancel cases from a cardiac stand point?
Electrolyte abnormalities
What causes depolarization of the atria and ventricles?
Sodium channels cause cell to cell conduction
What causes repolarization?
K+ outflow
What rate does the SA node generate action potentials?
60-100 bpm
What meds can be useful if the parasympathetic NS is overactive causing low HR?
Atropine and Glycopyrrolate
parasympathetic blockers (Anticholinergics)
What is the name for the conduction pathway from the SA node:
Through right atrium via internodal pathway
To left atrium via Bachmann’s bundle
Where is the AV node located?
Base of RA near inter ventricular septum
Pacemaker cells within the AV node generate APS at a rate of ________ bpm.
40-60
What is the purpose of the AV node having a delay? How long is the delay?
0.1 second
slowing down conduction velocity of the AP gives time for the atria to contract before the ventricles
What would happen if there was no delay at the AV node?
Atria and ventricles would be contracting at the same time–difficult for blood to flow properly
Where is the bundle of His located?
Interventricular septum
What rate do the pacer cells in the bundle of his generate APs at?
40-60 bpm
Where do idioventricular rhythms originate?
Ventricle
What are the 2 branches of the bundle of His?
Left and right branches (atrioventricular branches)
What is the rate at the left and right bundle branches?
20-40bpm
Where does the action potential travel after the bundle branches?
Purkinje fibers
What is the rate of APs generated by the purkinje fibers?
20-40bpm
What happens once the AP travels through the purkinje fibers?
Ventricular myocytes depolarize and contract (systole)
What is an example of a rate less than 20bpm?
Agonal rhythm
If a patient is in a high heart block, why should we not try giving atropine or glycopyrrolate?
Blocks are ventricular rates–not affected by the SA node
Would usually go to pacing
