CPT II - Midterm Flashcards
What is automaticity?
Ability of muscle cells to generate their own action potentials
What is rhythmicity?
Action potentials that occur at regular intervals.
What is the function of the intercalated discs in the myocardium?
Gap junctions allow AP to spread and polarize all cells at the same time.
What is a vulnerable period for dysrhythmias in the heart cycle?
During relative refractory period
What does diastole look like on EKG?
Flat line (no electrical activity)
Where is the SA node?
At the base of the superior vena cava (right atrium)
How do you LOOK for cardiac output?
Signs and symptoms
Blood pressure
EKG only shows what kind of heart activity?
Electrical (not mechanical)
When does the SA node fire typically?
When ventricles fill to 80%
What is the AV junction?
Where AV node meets bundle of His (near tricuspid valve)
Dysrhythmias occur as a result from…
altered conduction, rhythmicity, or both
What is an ectopic rhythm?
Rhythm in which the origin is not the SA node
How do dysrhythmias occur?
Hypoxia Ischemia or Irritability Sympathetic stimulation Drugs Electrolyte Disturbances Bradycardias Stretch
How many electrodes are in a 12-lead EKG? What is the purpose of having so many?
10 - each lead has a different view of the heart
What is a bipolar lead?
1 positive and 1 negative electrode
What are the 3 bipolar leads?
Leads I, II, III
What are the 3 unipolar leads?
Leads aVR, aVL, aVF
augmented views - right, left, foot
What is a unipolar lead?
1 positive electrode and 1 reference point
How many views do you need to diagnose a heart condition by EKG?
All 12
Dysrhythmias occur as a result from…
altered conduction, rhythmicity, or both
What is an ectopic rhythm?
Rhythm in which the origin is not the SA node
How do dysrhythmias occur?
Hypoxia Ischemia or Irritability Sympathetic stimulation Drugs Electrolyte Disturbances Bradycardias Stretch
How many electrodes are in a 12-lead EKG? What is the purpose of having so many?
10 - each lead has a different view of the heart
What are the inferior view leads?
II, III, AVF
Limb leads record activity in what plane?
Frontal
Chest leads record activity in what plane?
Horizontal
How many chest leads are there and what are they made up of?
Six unipolar leads made up of a positive electrode and a reference point near the AV node (V1 -> V6)
What is the MCL1 lead commonly used for?
Monitoring. Similar to lead II but now using 5 electrodes instead of 3
Where is the MCL1 positive electrode placed?
Over the 4th intercostal space just to the right of the sternum.
Where is the MCL1 negative electrode placed?
2nd intercostal space midline on the upper left chest or outer third of the left clavicle
What are the anterior view leads?
V1, V2, V3, V4
What are the lateral view leads?
I, AVL, V5, V6
What are the inferior view leads?
II, III, AVF
What is Q-T syndrome?
Prolonged Q-T interval; more danger of repolarization (dysrhythmia)
What is the best method to determine rate via EKG? What is an ok alternative?
Count out beats on full minute of tape
Ok: 6 second strip
What are the 4 places of origin for action potential?
SA node
Atrium
Junction
Ventricles
What is the flat line of diastole also called?
isoelectric line
What is the difference between a segment and an interval?
Segment - straight line
Interval - 1 wave and 1 segment
What is the P-R interval? Normal value?
Beginning of P wave to the beginning of the QRS complex
Normal: < 0.20 ms (5 boxes)
What is the S-T segment? How can it indicate infarction/ischemia?
Plateau phase
Ischemia: > 2 mm elevation or depression from isoelectric line
What is the Q-T interval?
Ventricular depolarization and repolarization
What part of the EKG represents the shift from absolute to relative refractory period?
Q-T interval
What is Q-T syndrome?
Prolonged Q-T interval; more danger of repolarization (dysrhythmia)
Why is sinus tachycardia during exercise not a concern in healthy individuals?
Increased venous return prevents decrease in stroke volume
Time: 1 small square, 1 large square, 5 large squares
1 small = 0.04 s
1 large = 0.2 s
5 large = 1 s
What do you think if you can’t see a P wave on EKG?
Atrial rate is absent OR
Tachycardia is hiding it
When do you use the box method?
For regular rhythm only
What is the best method to determine rate via EKG? What is an ok alternative?
Count out beats on full minute of tape
Ok: 6 minute strip
Normal Sinus Rhythm
Rhythm: regular Rate: 60-100 P waves: normal PR: normal QRS: normal
What is a premature atrial contraction?
For one beat, somewhere in the atria, one site fires faster than the SA node.
Often once or twice per minute.
SInus Tachycardia
Rhythm: regular Rate: 100-150 P waves: normal PR: normal QRS: normal
Sinus tachycardia has the potential to decrease…
stroke volume (less time in diastole)
Why is an accelerated heart rate during exercise not considered sinus tachycardia diagnostically?
Increased venous return prevents decrease in stroke volume
Sinus Arrhythmia
Rhythm: irregular Rate: varies w/ breathing P waves: normal PR: normal QRS: normal
How does the heart rate vary in sinus arrythmia?
Speeds up with inhalation
Slows down with exhalation
Premature atrial contraction
Rhythm: Reg underlying, Irreg at PAC Rate: Normal underlying P waves: Normal underlying PR: normal QRS: normal
How can you see an atrial dysrhythmia
Presence of P wave but it looks abnormal
Every cell in the heart has the ability to be its own pacemaker. SA node is primary because…
it’s fastest
What is a premature atrial contraction?
For one beat, somewhere in the atria, one site fires faster than the SA node.
Often once or twice per minute. Generally benign.
Premature Junctional Contraction
Rhythm: Regular underlying Rate: N underlying P waves: Before/During/After QRS PR: Absent QRS: normal
What does a retrograde depolarization look like?
Inverted wave
Premature Ventricular Contraction
Rhythm: regular underlying
Rate: N underlying
P waves: normal underlying, absent at PVC
PR: normal underlying, absent at PVC
QRS: normal underlying, wide/bizarre at PVC
Atrial Flutter
Rhythm: regular or irregular Rate: Atrial: 250-300 P waves: Flutter (F) waves PR: non-discernable QRS: normal
What is happening during atrial flutter?
Not all atrial depolarizations are getting through to the ventricles - several p waves before every QRS complex
Atrial Fibrillation
Rhythm: Irregular Rate: Uncontrolled > 100 P waves: Fibrillatory PR: Absent QRS: Normal
Unifocal vs. multifocal PVC
Unifocal: origin at one area
Multifocal: more than 1 area of origin
How can you determine a junctional dysrhythmia? Where does the AP originate?
No P wave; AP starts at the QRS complex (AV node)
Junctional Dysrhythmia
Rhythm: regular Rate: 40-60 P waves: absent PR: absent QRS: normal
Premature Junctional Contraction
Rhythm: Regular underlying Rate: 40-60 underlying P waves: Before/During/After QRS PR: Absent QRS: normal
What does a retrograde depolarization look like?
Inverted wave
Premature Ventricular Contraction
Rhythm: regular underlying
Rate: N underlying
P waves: normal underlying, absent at PVC
PR: normal underlying, absent at PVC
QRS: normal underlying, wide/bizarre at PVC
Implication on stroke volume with PVCs?
Lose the atrial kick which may decrease stroke volume (ventricles don’t fill all the way)
What do you do if there are < 6 PVC per min? > 6 per min?
< 6 = treat and monitor
> 6 = don’t aggravate it further, could compromise CO
Signs of aggravation of PVC condition
Amount of PVCs per minute increase
PVCs come from different locations
Unifocal vs. multifocal PVC
Unifocal: origin at one area
Multifocal: more than 1 area of origin
Ventricular Fibrillation
Rhythm: Absent Rate: Absent P waves: absent PR: absent QRS: fibrillatory
What is 3+ PVCs in a row?
Ventricular tachycardia
What is bigeminy?
Every other beat is a PVC
What is trigeminy?
Every third beat is a PVC
Multifocal PVCs look different from each other. What could they signify?
Increased irritation to the ventricles
Ventricular Tachycardia
Rhythm: regular Rate: 100-250 P waves: absent PR: absent QRS: wide and bizarre
What is happening with ventricular tachycardia?
Site is so irritated, it takes over as primary pacemaker.
What is important to know about V-tach?
It is life-threatening!! Patient needs to get shocked out of it.
What is non-sustained ventricular tachycardia?
3+ PVCs in a row but resolves on its own.