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50 Cards in this Set

  • Front
  • Back
what are biphasic deflections?
waves with both positive and negative components
What is the baseline?
it is a line from one TP segment to the next
How are tall QRS waves denoted? Small waves?
1) Capital letters Q,R,S, R'
2) lower case letters q,r,s,r'
When is a wave denoted r'?
if a short peak appears after the R wave
When r used to denote a wave?
if a small wave occurs before R' in the same direction as R'. Note that the second waves are denoted with a prime
What is the first negative wave seen after each p always called?
If an R and S wave are recorded and then another immediate positive wave off the S wave occurs what is it labeled?
What is the normal duration of the P wave?
0.08 to 0.11
What is the axis of the P wave?
down and to the left
axis: 0 to +75
What does the Tp wave represent? Why is it not seen?
1) repolarization of the atria
2) it is blended in with the QRS
What wave may be seen in an AV node block? When else can this wave be seen?
1) Tp wave may be present because there is no QRS
2) PR depression or ST segment depression present in fast sinus tachycardias
3) ST depression because the QRS comes sooner and the Tp wave draws the ST segment downwards
Under normal condition how far below baseline can the the PR segement be depressed?
What conditions would depress the PR segment?
pericarditis and atrial infarct
Where in the heart is the electrical impulse during a PR segment?
depolarizing AV node, his bundles, bundle branches and purkinje system
Is a PR of 0.10 normal?
no, normal is 0.11 to 0.2
What is a PR interval longer than 0.2 seconds indicative of?
first degree heart block
What is the normal QRS interval?
0.06 to 0.11 seconds
What is the normal axis of the QRS complex?
-30 to 105 downward and to the left
What can the Q wave indicate?
dead tissue
When is a Q wave considered significant?
if is wider than 0.03 sec or has a height greater than or equal to 1/3 the height of the R wave
Which leads generally have insignificant Q waves? why are they seen?
1) I, aVL, V6
2) they are due to septal innervation and called septal Qs
How is the intrinsicoid deflection measured?
beginning of QRS to the beginning of the negative down slope of the R wave in leads that do not have a Q wave
Which leads can't the intriniscoid deflection most likely be measured?
1, aVL and V6 because they typically have a Q wave
Why is the intrinsicoid deflection measured?
it represents the time it takes for the impulse to travel from the purkinje system in the endocardium to the epicardial surface
In which leads is the intrinsicoid deflection less than 0.035 seconds?
right precordials V1 and V2 measure right ventricle
In leads V5 and V6 the intrinsicoid deflection can be measured to be how long?
0.045 seconds but is wider than the right ventricle because of greater thickness
What two conditions can prolong the intrinsicoid deflection?
1) thicker myocardium
2) intraventricular conduction delay like bbb
Where does the J point occur?
the point where the QRS ends and the ST segment begins
In relation to the TP segment where is the J point?
even at basline
How much can the J point vary in limb leads and still be normal? how far in the right precordials?
1) 1 mm from baseline
2) 3 mm
What can cause J point deviation?
1) left ventricular hypertrophy
2) early repolarization pattern
Any ST elevation in a symptomatic patient should be treated as what?
myocardial injury or MI until proven otherwise
What occurs in the ST segment electrically speaking?
electrically neutral period between ventricular repolarization and depolarization
What is the axis of the ST segment?
inferior and to left
What is occurring mechanically during the ST segment?
The myocardium is maintaining contraction
Why is the T wave a positive deflection?
because of increased pressure on the endocardium the during contraction the repolarization wave begins in the epicardium and travels to the endocardium. Meaning that the epicardium becomes positive first which is detected as positive by the chest leads. it is essentially a negative wave traveling away from the heart and a positive one traveling towards the surface
Should the T wave be symmetrical?
no the first part rises slower and the 2nd part drops quicker
What is the axis of the T wave?
downward and to the left
What is a long QT a harbinger of?
arrythmias and torsade de pointes
What is the relation of the QT to the RR interval?
QT should be shorter than 1/2 the RR
What does QTc correct for?
heart rate
What is the relation of heart rate to the QT interval length?
decreased heart rate increases QT interval

increased heart rate decreases QT interval
What is the formula for calculating QTc?
QTc = QT + 1.75(vent rate - 60)
What events are represented by QTc?
everything in ventricular systole
What is the normal duration of QTc? what is prolonged?
1) 0.410
2) >0.419
When is the U wave seen and what its features?
It is seen after the T wave or before the P wave. they are small flat waves
When are U waves seen?
when there is hypokalemia, in a normal heart, bradycardia.
The presence of a U wave means that there is no chance of what condition?
What is the clinical significance of the U wave?
that it can hinder accurate measurement of the QT interval
regular rhythms have what?
consistent R-R intervals