EKG Practice- Nordgren Flashcards
What is rapid way to figure out the heart rate when looking at an EKG?
Count large boxes between R-R peaks
300 150 100 75 60 50
What does the P wave represent? And what is its normal duration?
P wave represents atrial depolarization
Normal value is less that .12 secs (or 120 msecs)
What should you suspect if you see a increased amplitude in a P wave? what about a notch? (in lead II)
Taller P wave = R atrial hypertrophy
Notched P wave = L atrial hypertrophy
What should you suspect if you see a unproportional euphasic P wave in lead V1?
If the first part is larger = R atrium hypertrophy
If the second part is more negative = L atrium hypertrophy
What does the PR interval measure? How long should in normally be?
PR interval represents the time of conduction of impulse propagation through the AV node
Should be less than 200 ms (.2 seconds)
What does the QRS complex represent? How long should it be?
QRS complex represents ventricular depolarizaiton and hsould last 60-10 ms (.06-.1 secs)
What does the ST segment represent? What does ST elevation or depression represent?
Plateu phase of ventricular APs.
ST Depression - Non-transmural ischemia
- Damaged tissue is partially through wall, gives off currrent
- Current is travelling towards + electrode
- PR interval is raised (ST segment appears depressed)
ST Elevation- Transmural ischemia
- Damaged tissue is all the way through wall, gives off current
- Current travels in direction AWAY from + elctrode
- PR interval is depressed (ST segment appears elevated)
What are the consequences of a stenotic valve?
Valve does not open fully
Champer upstream has to develop more pressure during systole phase in order to achieve a give flow through valve
Increases “pressure” work (afterload)
Leads to hypertrophy of preceding chamber
What are the consequences on an insufficient valve?
The valve doesn’t close completely
Regurgitant blood flow represents an additional volume that must be ejected in order to get sufficent forward flow
Increases “volume” work (stroke volume)
Leads to chamber dilation
Paroxysmal Supraventricular Tachycardia
Fast Rate
Narrow QRS (originates above the ventricles)
Begins and ends suddenly (blue arrow)
P and T wave may be super imposed because of high HR
Low blood pressure (not adequate filling time) and dizziness common
Sinuse Node Dysfunction
Describe the differences in degrees of conduction blocks
First degree = abnormally long P-R interval (>200 ms)
Second degree = some, but not all P waves are accompanied by QRS and T waves
Third degree = no conduction through AV node, pacemaker defaults to HIS, P waves and QRS are totally dissociated
Premature Atrial contractions (PACs) = early extra beats that orginate in the atria
What is the characteristic “delta wave” and when would you see it?
The delta wave = slurred upstroke on the QRS complex
Seen in accessory pathway tachycardias
Rapid heart rhythm due to an extra abnormal pathway or connection between the atria and the ventricles
Impulses travels through “short cuts” and normal AV-HIs purkinje system
Ex: Wolff-Parkinson-White Syndrome
Atrial Flutter
Atrial Fibrillation
Bundle Branch Block
Occcur in either of the purkinje branshes
Often due to MI
Widening of QRS (?.12) because ventricular deporization less synchronous in half the heart
Splitting of R wave
Premature Ventricular Contractions
Ventricular Tachycardia
Rapid rate prevents hte heart from filling adequately with blood
SERIOUS CONDITION - often preceds ventricular fibrillation
If you saw this, what would the patient be at increased risk for?
Long QT syndrome
Long QT interval = long tie for heart muscle to contract and then recover
Increased risk for TORSADE DE POINTES
Ventricular Fibrillation
No pumping action occurs
Treat with CPR and difibrillation as soon as possible!
