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Principles I Test 3

EKG

QuestionAnswer
Primary pacemaker of heart. Located in junction of the superior vena cava and right atrium. SA node
What is the inherent rate of the SA node? 60 - 100 bpm
The conductive pathway between the atria and the ventricles. Can take over as pacemaker is SA node fails. AV node
What is the inherent rate of the AV node? 40 - 60 bpm
What is the inherent rate of the ventricles/ purkinje network? 20 - 40 bpm
Each cardiac cycle is activated by the __________ of the heart and is completed through ___________ __________. automaticity; electrolyte changes
What is the normal resting charge of the cardiac cell? -90 mV
Depolarization occurs by the cell becoming "positive"; to a point of _______ +30 mV
During depolarization, _____ enters the cell to make is more positive and _____ leaves the cell. Na+ enters cell; K+ leaves cell
During depolarization, ______ also enters the cell more slowly, facilitating a prolonged conduction. Ca++
True or False: the depolarization is synonymous with the discharge of energy from the cell and is continuous cycle that occurs to stimulate the mechanical function of each heart beat. True!
Repolarization begins with the entrance of ____ making the cell more negative. Cl-
Repolarization returns the cell to its ____________ resting state
During depolarization, _____ is pumped back out off the call and begins to return to the inside of the cell Na+
What is the absolute refractory period? the time during repolarization where no matter the stimulus, the cell cannot be depolarized again
What does the absolute refractory period ensure? a complete re-charge before the next cardiac cycle
What is the relative refractory period? The time when the cell has completed a portion of the repolarization, but has not completed the whole process. The cell can depolarize again, but it is more difficult to stimulate.
Sometimes stimuli during the relative refractory period can cause what? lethal dysrhythmias
True or False: medications cannot predispose conduction during the relative refractory period False! Medications can predispose conduction during the relive refractory period
What are ectopic sites or foci? Non pacemaker cells that suddenly discharge on their own, similar to the automatic discharge of the SA node; they cause certain dysrhythmias.
This type of rhythm is a complication with the conduction pathway & may cause fast repeating beats that often require emergent care to break the cycle. Re-entry rhythms
What is the EKG a picture of? the electrical activity of the heart
What is a lead? the view of the electrical activity of the heart between 2 electrodes
Which are the bipolar limb leads? Where are they located? I, II, III; Located between right arm, left arm and left leg
Which are the unipolar augmented leads? Where are they located? aVR, aVL, aVF; between a limb lead and a reference point (AV node)
Which are the unipolar precordial leads? Where are they located? V1, V2, V3, V4, V5, V6; between a chest lead and a reference point (AV node)
What are modified chest leads and when would they be used? In the absence of a 12 lead capable machine, normal monitoring leads (bipolar) can be modified to mimic precordial views.
Where should the V1 lead be placed anatomically? 4th ICS RSB
Where should the V2 lead be placed anatomically? 4th ICS LSB
Where should the V3 lead be placed? between V2 and V4
Where should the V4 lead be placed anatomically? 5th ICS MCL
Where should the V5 lead be placed? between V4 and V6
Where should the V6 lead be placed anatomically? 5th ICS MAL
True of False: V leads should be placed on top of breast tissue. False! V leads should be placed underneath breast tissue.
One small box on the EKG graph paper represents how much time? 0.04 seconds
One large box on the EKG graph paper represents how much time? 0.2 seconds
One small box on the EKG graph paper represents how much voltage? 0.1 mV
One large box on the EKG graph paper represents how much voltage? 1 mV
What happens when you change the size on your EKG monitor? increases the scale of the tracing to enlarge the entire complex; allows for easier viewing but may distort features
What is the standard size calibration on an EKG monitor? 10 mm or 2 big blocks
What is gain (as it related to EKG)? sensitivity; the more sensitivity the better the reception but it may increase artifact; filter mode = less gain; monitor mode = more gain
A normal PR interval is how long? < .2 seconds (1 big box or 5 small boxes) (.12 - .2 seconds)
A normal QRS is how long? < .12 seconds (3 small boxes) (.06 - .1 seconds)
True or false: both the QT and PR intervals are rate dependent. False!!!! The QT interval is rate dependent, BUT the PR interval is independent of rate
What is a quick method for determining whether or not a patient has a prolonged QT internal? Draw a line down 2 consecutive Q waves. Draw a line halfway between the 2 Q waves. If T wave occurs at halfway mark or close to it, QT is prolonged/abnormal
What is the quickest method to measure rate on a 6 second EKG strip? count the number of QRS complexes and multiply by 10
True or False: there is no need to take a radial pulse and count the rate if you have an EKG strip. False! An EKG strip is only a reflection of electrical conduction, NOT mechanical conduction. Electrical rate and mechanical rate can be different
What is the R to R interval method for determining rate from an EKG strip? measure R to R duration in seconds and divide number into 60; OR count large boxes between R waves and divide number into 300.
What is the triplicate method for determining rate from an EKG strip? Locate R wave that falls on dark line bordering large box. Assign 300/150/100/75/60/50 in that order to next 6 dark lines to right. Number corresponding to dark line at peak of next R wave is rate.
What does the P wave represent? atrial depolarization
What is the typical duration and height of the P wave? 0.06 - 0.1 seconds duration and </= 2.5 mm in height
What does the QRS represent? ventricular depolarization; Q wave = septal depolarization; R wave = positive deflection during vent. depol.; S wave = negative deflection after R wave
What does the ST segment represent? the time between depolarization and repolarization of the ventricles; should be isoelectric with the baseline
What is the J-point? the level at which the ST segment begins from the QRS complex
What does the T wave represent? ventricular repolarization
What 3 things can influence the T wave and cause changes in its appearance? drugs, ischemia and electrolytes
What is the rate range for sinus tachycardia? > 100 but < 150; SA node is NOT capable of generating a rate > 150.
True or False: in sinus arrhythmia/dysrhythmia there is an ectopic pacemaker. FALSE! No ectopic pacer, just irregular firing of the SA node
In what patient population would you most likely se a sinus arrhythmia? How can you fix the problem? Young, healthy hypovolemic patients on the ventilator. Fix by turning down PEEP (unless difficulty ventilating) and giving them volume.
What are the 4 dysrhythmias originating in the SA node? Sinus bradycardia, sinus tachycardia, sinus dysrhythmia, sinus arrest
What is the difference between a wandering pacemaker rhythm and a sinus dysrhythmia? In wandering pacemaker rhythm, the morphology of each P wave is different indicating a changing pacer site; In sinus dysrhythmia all beats come from SA node, just has irregular rate
What are the 5 atrial dysrhythmias? wandering pacemaker, PACs, PSVT, atrial flutter, atrial fibrillation
What are junctional rhythms characterized by and what is the typical rate? retrograde conduction of the atria; occurs secondary to inadequately firing AV node; inherent rate 40 - 60; accelerated = 60 - 100
What are the 4 junctional dysrhythmias? PJCs, junctional escape rhythm, accelerated junctional, junctional tachycardia
3 or more PVCs in a row is considered to be what? a run of V-tach
What is different about the PR interval in first degree heart block? Is anything else about this rhythm abnormal? PR interval is constant but prolonged (> 0.2 seconds) ; This is only abnormality with this dysrhythmia.
What is different about the PR interval in second degree type I heart block (Wenckebach)? Is it a regular rhythm? PR interval continues to widen before resetting (cyclical); QRS rate is irregular, but the P to P interval is regular.
What is different about the PR interval in second degree type II heart block (classical)? Is it a regular rhythm? PR interval is constant for the last P wave, though there are multiple P waves per QRS; QRS and P waves are regular
What occurs in third degree heart block (complete)? Complete dissociation between P and QRS complexes; P to P intervals are regular and QRS to QRS intervals are regular, but PR intervals inconsistent
What EKG changes will you see with pericarditis? Elevated, concave ST segment
What EKG changes will you see with hyperkalemia? Tall, peaked T wave; wide flat P wave; widening QRS; disappearing ST segment; merging QRS and T wave
What EKG changes will you see with hypokalemia? Appearance of U waves; ST segment depression; flattening T waves; Widening QRS
What EKG changes will you see with hypercalcemia? Short QT intervals
What EKG changes will you see with hypocalcemia? Prolonged QT intervals
What EKG changes are known as the "digitalis effect"? depressed "scooped" ST segments; flat, inverted or biphasic T waves; short QT intervals
If this lead is placed too high on the chest, you will have a false ST elevation. Red lead
Which two leads do you look at on an EKG to determine whether or not the axis is normal? lead I and AVF
If both lead I and AVF are positive, what does that indicate about this axis? it is normal
If lead I is positive and AVF is negative, what does that indicate about the axis? left axis deviation
If lead I is negative and AVF is positive, what does that indicate about the axis? right axis deviation
What are some possible causes of a left axis deviation? right sided infarct, enlarged left ventricle, pregnancy
What are some possible causes of right axis deviation? left sided infarct; tall thin people r/t physical displacement of the heart at baseline
In a right bundle branch block, the r - R' is found in which 2 leads? V1 and/or V2
In a left bundle branch block, the r - R' wave if found in which leads? Which lead is the deep Q wave present in? V5 and/or V6 for r - R'; V1 for Q wave
If you notice a wide QRS ( > 0.12 seconds ) which leads would you look in to check for a bundle branch block? V1, V2, V5, V6
Which lead is the best place to look to distinguish between a right and left bundle branch block? V1
ACLS protocol says to treat a new __________ as an MI until proven otherwise. left bundle branch block; especially in the presence of CV surgery
When considering the placement of a PA catheter, if there is already a LBBB present, the PA catheter may stimulate what? a RBBB; LBBB + RBBB = complete heart block (3rd degree)
Which leads look at the inferior wall of the heart? Which coronary artery supplies this area of the heart? II, III, AVF; inferior wall supplied RCA
Which leads look at the lateral wall of the heart? Which coronary arteries supply this area of the heart? I, AVL, V5, V6; lateral wall supplied by L circumflex / RCA
Which leads look at the septal wall? Which coronary arteries supply this area? V1, V2; septal wall supplied by LAD
Which leads look at the anterior wall? Which coronary arteries supply this area? V3, V4; anterior wall supplied by LAD
12 leads look at the whole picture of the ____________ left ventricle
True or false: in determining ischemia, injury or infarction, you must identify similar changes in 2 or more leads, no matter which 2 leads. False! You must identify similar changes in 2 or more leads that represent the same area of the heart.
What EKG changes indicate ischemia? tall or peaked T waves, inverted symmetrical T waves, ST depression
What EKG changes indicate injury? ST elevation
What EKG changes indicate infarction? Q wave formation; normal is < 0.03 seconds (1 small box) and 1/3 height of R wave
True or false: a Q wave is not always present in less severe infarctions True
The treatment for any type of ischemia is the same. What is it? Increase O2 supply and decrease O2 demand
Which 2 leads are the best to monitor? II and V5
Which lead is the best for detecting atrial dysrhythmias? lead II
Which lead is the best for detecting ischemia? V5
Monitoring Lead II + V5 detects what percentage of ischemic events? 80%
Monitoring V5 + V4 detects what percentage of ischemic events? 90%
Monitoring Lead II + V5 + V4 detects what percentage of ischemic events? 96%
What would you see on an EKG that is indicative of left atrial hypertrophy? a notched P wave in V1, a biphasic or widened P wave in lead I or V1
What would you see on an EKG that is indicative of right atrial hypertrophy? a tall, peaked P wave
What EKG findings are indicative of right ventricular hypertrophy? a large R wave in V1, which gets progressively smaller in V2, V3, and V4
What EKG findings are indicative of left ventricular hypertrophy? a very large QS wave in V1 and a very large R wave in V6
How do you calculate whether or not a patient has left ventricular hypertrophy based on their EKG? measure the depth of the S wave in V1 and the height of the R wave in V6; if the two measurements add together and are > 35 mm LVH is present
What are some causes of LVH? long standing essential HTN, aortic valve stenosis, idiopathic hypertrophic sub aortic stenosis
What EKG findings would you see in a patient with Wolfe-Parkinson-White (WPW)? short P-R interval and a sloping R wave
If there is an unusual rhythm on the monitor or you notice a rhythm change, what should be your immediate next step? check a pulse
Created by: Mary Beth