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50 Cards in this Set
- Front
- Back
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what are biphasic deflections?
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waves with both positive and negative components
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What is the baseline?
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it is a line from one TP segment to the next
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How are tall QRS waves denoted? Small waves?
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1) Capital letters Q,R,S, R'
2) lower case letters q,r,s,r' |
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When is a wave denoted r'?
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if a short peak appears after the R wave
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When r used to denote a wave?
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if a small wave occurs before R' in the same direction as R'. Note that the second waves are denoted with a prime
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What is the first negative wave seen after each p always called?
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Q
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If an R and S wave are recorded and then another immediate positive wave off the S wave occurs what is it labeled?
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R'
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What is the normal duration of the P wave?
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0.08 to 0.11
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What is the axis of the P wave?
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down and to the left
axis: 0 to +75 |
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What does the Tp wave represent? Why is it not seen?
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1) repolarization of the atria
2) it is blended in with the QRS |
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What wave may be seen in an AV node block? When else can this wave be seen?
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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 |
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Under normal condition how far below baseline can the the PR segement be depressed?
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0.8mm
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What conditions would depress the PR segment?
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pericarditis and atrial infarct
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Where in the heart is the electrical impulse during a PR segment?
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depolarizing AV node, his bundles, bundle branches and purkinje system
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Is a PR of 0.10 normal?
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no, normal is 0.11 to 0.2
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What is a PR interval longer than 0.2 seconds indicative of?
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first degree heart block
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What is the normal QRS interval?
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0.06 to 0.11 seconds
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What is the normal axis of the QRS complex?
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-30 to 105 downward and to the left
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What can the Q wave indicate?
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dead tissue
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When is a Q wave considered significant?
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if is wider than 0.03 sec or has a height greater than or equal to 1/3 the height of the R wave
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Which leads generally have insignificant Q waves? why are they seen?
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1) I, aVL, V6
2) they are due to septal innervation and called septal Qs |
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How is the intrinsicoid deflection measured?
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beginning of QRS to the beginning of the negative down slope of the R wave in leads that do not have a Q wave
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Which leads can't the intriniscoid deflection most likely be measured?
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1, aVL and V6 because they typically have a Q wave
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Why is the intrinsicoid deflection measured?
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it represents the time it takes for the impulse to travel from the purkinje system in the endocardium to the epicardial surface
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In which leads is the intrinsicoid deflection less than 0.035 seconds?
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right precordials V1 and V2 measure right ventricle
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In leads V5 and V6 the intrinsicoid deflection can be measured to be how long?
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0.045 seconds but is wider than the right ventricle because of greater thickness
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What two conditions can prolong the intrinsicoid deflection?
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1) thicker myocardium
2) intraventricular conduction delay like bbb |
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Where does the J point occur?
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the point where the QRS ends and the ST segment begins
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In relation to the TP segment where is the J point?
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even at basline
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How much can the J point vary in limb leads and still be normal? how far in the right precordials?
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1) 1 mm from baseline
2) 3 mm |
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What can cause J point deviation?
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1) left ventricular hypertrophy
2) early repolarization pattern |
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Any ST elevation in a symptomatic patient should be treated as what?
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myocardial injury or MI until proven otherwise
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What occurs in the ST segment electrically speaking?
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electrically neutral period between ventricular repolarization and depolarization
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What is the axis of the ST segment?
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inferior and to left
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What is occurring mechanically during the ST segment?
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The myocardium is maintaining contraction
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Why is the T wave a positive deflection?
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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
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Should the T wave be symmetrical?
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no the first part rises slower and the 2nd part drops quicker
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What is the axis of the T wave?
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downward and to the left
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What is a long QT a harbinger of?
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arrythmias and torsade de pointes
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What is the relation of the QT to the RR interval?
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QT should be shorter than 1/2 the RR
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What does QTc correct for?
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heart rate
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What is the relation of heart rate to the QT interval length?
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decreased heart rate increases QT interval
increased heart rate decreases QT interval |
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What is the formula for calculating QTc?
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QTc = QT + 1.75(vent rate - 60)
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What events are represented by QTc?
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everything in ventricular systole
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What is the normal duration of QTc? what is prolonged?
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1) 0.410
2) >0.419 |
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When is the U wave seen and what its features?
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It is seen after the T wave or before the P wave. they are small flat waves
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When are U waves seen?
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when there is hypokalemia, in a normal heart, bradycardia.
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The presence of a U wave means that there is no chance of what condition?
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hyperkalemia
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What is the clinical significance of the U wave?
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that it can hinder accurate measurement of the QT interval
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regular rhythms have what?
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consistent R-R intervals
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