Term
| PR interval represents what? how long is normal for this interval? |
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Definition
| AV conduction; normal is < or = to 200 ms |
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Term
| what is the normal time of a QRS wave? what is considered abnormal? |
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Definition
| normal 60-100ms; intraventricular conduction delay 100-120ms; bundle branch block >120ms |
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Term
| what does QT represent? how long is normal? |
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Definition
| ventricular repolarization; 400ms is normal |
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Term
| what is a quick way to calculate HR from an EKG? |
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Definition
| QRS peak separation: 1 block = 300pbm; 2 blocks = 150 bpm; 3 blocks = 100bpm; 4 blocks = 75bpm; 5 blocks=60bpm; 6 blocks = 50 bpm. (60,000/ms between peaks) |
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Term
| one small box on an EKG represents how many ms? large box? |
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Definition
| small box = 40ms; large box = 200 ms |
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Term
| who has a normal bradycardia? |
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Definition
| conditioned athletes and non-stressed people (stronger heart beat = less frequent heart beat) |
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Term
| when would you see P on T phenomenon? |
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Definition
| tachycardia moves P and T waves closer together, sometimes the T wave is superimposed on the P wave. in sinus tachy, can still distinguish P, QRS, T |
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Term
| if we have abnormal beats but theyre the same width as the other normal QRS waves (narrow) what do we assume? |
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Definition
| they're coming from the same source as the regular beats aka somewhere in the atrium, although not necessarily the SA node |
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Term
| how do we calculate max HR? and what is needed in stress test? |
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Definition
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Term
| what do we call it when there is irregularity between QRS rhythms? |
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Definition
| variable ventricular response or variable block |
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Term
| in which heart problem would you see a saw tooth pattern on the EKG? |
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Definition
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Term
| describe atrial fibrillation |
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Definition
| rapid irregular irregular rhythm with no P waves (chaotic, 400-650 bpm) |
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Term
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Definition
| atria and ventricle dissociated, lots and lots of P waves at fast rate and QRS waves (not a 1:1 ratio with P waves) every now and then, irregularly placed and slow |
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Term
| where is the source of trigger for atrial fibrillation? |
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Definition
| LUNG (pulmonary veins send signals at a fast rate to the heart, irritates the heart) |
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Term
| 98% of ventricular beats that originate in the heart are? |
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Definition
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Term
| define bigeminy, trigeminy, etc. |
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Definition
| bigeminy: 1 normal beat and 1 VPD; trigeminy= 2 normal beats and 1 VPD |
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Term
| what rate is normal for the SA node, AV node and ventricles to beat? |
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Definition
| SA = 60-100; AV=40-60; ventricles <40 |
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Term
| what usually causes accelerated idioventricular rhythm? |
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Definition
| usually occurs with reperfusion after an MI. indicates that an artery has been opened successfully. NOT re-entrant; AUTOMATIC! |
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Term
| monomorphic vs polymorphic |
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Definition
| monomorphic = redundant and abnormal but same morphology for all peaks; polymorphic = redundant and abnormal but peaks look diff from each other |
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Term
| how can a person overcome first or second degree heart block? |
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Definition
| exercise - patient has enough adrenaline/reserve to overcome the block (if exercise makes it worse, they need a pacemaker) |
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Term
| describe first degree AV block |
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Definition
| prolonged PR interval, constant relationship between P and QRS >200ms and 1:1 relationship between P, QRS, and T waves |
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Term
| 1st degree heart block is usually caused by what? and originates where? |
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Definition
| usually in AV node and is related to vagal tone. if we get rid of vagal tone by stimulating them (exercise, adrenaline) then we can get rid of it and overcome it |
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Term
| describe the 3 kinds of second degree AV block |
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Definition
| mobitz type 1 = PR interval gets longer and longer with each beat until get a P wave without a QRS; mobitz type II = abrupt drop of QRS; mobitz II to I = can't tell if its 1 or 2 because dropping QRS every other beat so we cannot see if the PR is prolonged |
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Term
| what is a common EKG abnormality that 75% of people have in their sleep and is of no consequence? |
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Definition
| wenckeback (mobitz type I second degree AV block) fine bc we wake up and have enough adrenaline to overcome it |
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Term
| where is the location of the problem in a mobitz type II second degree AV block? |
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Definition
| at the his/purkinje system (below the AV node) --> therefore the QRS is WIDE. these are unstable and dangerous (need pacemaker) |
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Term
| describe 3rd degree AV block |
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Definition
| NO relationship between P and QRS (either more P = 3rd or complete block or less P = A/V dissociation) NO fixed PR interval |
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Term
| what is the most common cause of complete heart block |
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Definition
| MI in right coronary artery |
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Term
| what is the clinical significance of making a distinction between complete heart block (more Ps than QRS) and AV dissociation (less Ps than QRS)? |
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Definition
| when you have LESS Ps, you can give adrenaline and increase the sinus rate and theres a chance the patient will conduct more and catch up to the ventricular rate. if theres MORE Ps, and we give adrenaline, we get a DECREASE in ventricular response because they already cant accommodate the beats they have |
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Term
| phase 0 of the AP corresponds to what part of the EKG? |
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Definition
| phase 0 - upstroke of AP = upstroke of QRS |
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Term
| when do the absolute and relative refractory periods occur in the AP? |
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Definition
| absolute refractory period starts at end of phase 1 and extends sometime into phase 3. relative refractory period occurs at the end of phase 3. |
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Term
| what interval shortens in all of us when we exercise? |
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Definition
| QT interval (except in people with long QT syndrome, usually female athletes --> sudden death) |
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Term
| what are the 2 things that determine how quickly impulses are conducted through the heart? |
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Definition
| 1. conduction velocity (slope of phase 0 upstroke) and 2. the refractoriness of the repolarization of the cell |
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Term
| majority of antiarrhythmic drugs work on which phase of the AP? |
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Definition
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Term
| describe the difference between normal and abnormal automaticity |
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Definition
| normal: SA node is still the pacemaker, introduction of catecholamines can signal the heart to increase HR to meet body's demands; abnormal: myocardial cells OUTSIDE the specialized conduction system acquire automaticity and spontaneously depolarize with the rate of depol exceeding that of the sinus node, so that they take over the pacemaker function and become the source of an abnormal ectopic rhythm |
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Term
| what normal and abnormal things can lead to automatic rhythms? |
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Definition
| normal: caffeine, adrenaline, catecholamines; abnormal: MI and reperfusion, electrolyte imbalance, |
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Term
| what keeps the sinus node beating the fastest (keeps it as the pacemaker)? |
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Definition
| steeper slope and less negative resting potential |
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Term
| what causes the action potential (QT) to be prolonged |
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Definition
| potassium low, magnesium low, or a drug, increased sympathetic tone, decreased parasympathetic tone, hypoxemia, acidosis, bradycardia (prolonging QT increases propensity for EAD) |
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Term
| what causes torsades de pointes? |
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Definition
| its a specific ventricular arrhythmia caused by early afterdepolarizations (triggered activity) |
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Term
| what causes sudden death in people with inherited long QT syndrome? |
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Definition
| early afterdepolarizations are more likely to develop in conditions that prolong the AP duration (QT interval) |
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Term
| what things lead to late afterdepolarizations? |
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Definition
| digitalis/digoxin toxicity and other cardiac glycosides(it leads to delayed repolarizations), low potassium, increased calcium, stress |
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Term
| what do early and late after depolarizations cause? |
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Definition
| EAD --> torsades de pointes (specific polymorphic ventricular tachycardia); DAD --> frequent ventricular premature depolarizations and palpitations |
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Term
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Definition
| 1. 2 parallel conducting pathways connected to tissue both proximally and distally 2. difference in the refractoriness of the 2 pathways 3. initiating event |
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Term
| for reentry, 2 diff conducting pathways have different tissue properties, what are the two types of tissue properties you need? |
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Definition
| 1. slow conduction with shorter refractory period 2. faster conduction with longer refractory period |
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Term
| what are the 2 types of re-entry |
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Definition
| macroscopic and microscopic |
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Term
| what maneuver can we teach pts to help with reentry arrhythmias? |
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Definition
| vagal maneuvers (bowel movement type) because when you strain a certain way you increase your vagal tone enough to disrupt the circuit if meds dont help |
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Term
| what is wolff-parkinson-white syndrome? |
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Definition
| collagen around valve not fully developed --> very THIN defect in the mitral or tricuspid valve --> heart can beat through AV node or through accessory pathway (faster and no filter) --> short PR interval --> can cause a re-entry loop |
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