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Principles I Test 3
EKG
| Question | Answer |
|---|---|
| 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
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