EKG Quiz Flashcards
ST segment represents what?
first phase of ventricular repolarization
T wave represents what?
Final phase of ventricular repolarization
Small squares are how much time?
0.04 seconds
bold squares are how much time?
0.2 seconds
Rate range of atrial foci?
60-80bpm
Rate range of junctional foci?
40-60bpm
Rate range of ventricular foci?
20-40bpm
Cause of sinus arrhythmia?
Parasympathetic and sympathetic activation in response to respiration.
Name of the conduction branch of the left atrium?
Bachmann’s Bundle
What do we call “entrance block”?
Parasystole
Wandering Pacemaker
- pacemaker activity wanders to nearby atrial focus
- cycle length variation
- P’ wave variation
- <100bpm
Multifocal Atrial Tachycardia
- pacemaker activity wanders to nearby atrial foci
- cycle length variation
- P’ wave variation
- > 100bpm
Atrial Fibrillation
- firing of multiple irritable, parasystolic atrial foci at once
- no real P waves (kind of a wavy baseline)
- irregular QRS complexes
Atrial Escape Rhythm
- due to sinus arrest
- P’ waves at a regular rate
- slower rate than sinus pacing (60-80bpm)
Junctional Escape Rhythm
- due to sinus arrest and atrial foci failure or conduction block at the proximal portion of the AV node
- either no P waves or inverted P’ waves (retrograde depolarization)
- lone QRS complexes
- 40-60bpm
Ventricular Escape Rhythm
- due to complete conduction block high in the ventricular conduction system or to downward displacement of the pacemaker (if all foci above fail)
- If the former, there will be P waves regularly, but they’re “overlaid” on top of regularly paced (but slow) QRS complexes at a different rate
- if the latter cause, then there will only be QRS complexes at 20-40bpm
Atrial Escape Beat
- due to transient sinus block
- pause followed by single P’ wave + cycle
- normal pacing resumes
Junctional Escape Beat
- due to sinus block and no atrial response
- pause, followed by QRS w/o P wave
Ventricular Escape Beat
- due to burst of parasympathetic activity, depressing the SA node, atrial foci and junctional foci
- pause, followed by enormous QRS w/o P wave
Premature Atrial Beat (PAB)
- due to an irritable atrial focus
- P’ wave earlier than expected
- P’ is up if in superior portion of atrium or inverted if in lower portion of atrium
- SA node is reset and normal pacing resumes
PAB with Aberrant Ventricular Conduction
- due to premature atrial beat conducted to ventricles when one bundle branch isn’t done repolarizing yet
- P’ wave with slightly wide QRS
- SA node is reset and normal pacing resumes
Non-Conducted PAB
- due to a premature atrial beat that hits the ventricles in a refractory periord
- P’ wave earlier than expected followed by no QRS complex
- SA node is reset and normal pacing resumes
Atrial Bigeminy
- due to an irritable atrial focus that fires after every normal cycle
- SA node is reset producing a span of clear baseline after every couplet
Atrial Trigeminy
- due to an irritable atrial focus that fires at the end of every second normal cycle
- SA node is reset, producing a span of clear baseline after every couplet
Premature Junctional Beat
- due to an irritable junctional focus
- depolarizes ventricles and sometimes atria in retrograde fashion
- widened QRS complex without P wave if no retrograde atrial depolarization
- if atrial depolarization, there can be an inverted P’ wave before, during, or after the QRS complex
- SA node will be reset if atria depolarize
Premature Ventricular Contraction
- irritable ventricular focus
- very wide and often inverted QRS complexes because one part of the ventricles depolarizes before the rest
- there may be many PVCs because a focus is very irritable
- there may be a long series of PVCs because a focus is parasystolic
- a run of three or more is ventricular tachycardia
Multifocal Premature Ventricular Contractions
- PVCs that are due to several different irritable focuses
- each PVC produces a unique QRS complex
Mitral Valve Prolapse
Can cause PVC because it causes localized stretch
Paroxysmal Atrial Tachycardia
- due to sudden, rapid firing of an atrial focus at 150-250bpm
- P’ wave before every QRS-T
Paroxysmal Atrial Tachycardia with block
- two P’ waves for every QRS-T
- often caused by digitalis overdose/toxicity
Paroxysmal Junctional Tachycardia
- due to a sudden, rapid firing of a junctional focus at 150-250bpm
- may be no P wave if atria are not depolarized
- if they are, there will be an inverted P’ wave either before, during, or after the QRS complex
- possible widened QRS complex due to aberrant ventricular conduction
AV Nodal Re-entry Tachycardia
-Looks like paroxysmal junctional tachy, but is really due to a reentry circuit
Paroxysmal Ventricular Tachycardia
- due to a sudden, rapid firing of a ventricular focus at 150-250bpm
- often due to poor oxygenation of the heart
- really just a run of PVCs
- widened QRS complexes
- SA node is still pacing atria, so we have normally-timed P waves
- sometimes the SA node depolarization reaches the AV node and produces a normal or fusion QRS complex
Torsades de Pointes
- due to low K+, drugs that block K+ channels, or congenital defect
- rapid ventricular rhythm with lengthened QT segment
- 150-250bpm
- QRS point up, then down and get smaller, then bigger
Atrial Flutter
- due to rapid atrial depolarization at 250-350/min
- produces rapid, identical P’ waves with QRS complex every 2-3 P’ waves
Ventricular Flutter
- due to rapid firing of a single ventricular focus at 250-350/min
- produces rapid sine-like waves
Ventricular Fibrillation
- due to many irritable, parasystolic ventricular foci firing at once
- rapid twitching of the ventricles (very bad)
- erratic, unidentifiable waves on EKG
Wolff-Parkinson-White Syndrome
- due to the Bundle of Kent “short-circuiting” the atrial conduction, prematurely depolarizing a portion of the ventricles
- produces a delta wave on EKG
- can lead to paroxysmal tachycardia
Lown-Ganong-Levine Syndrome
- due to the AV node being bypassed by the James Bundle, which depolarizes the ventricles without conduction-delay via the AV node
- P waves are right next to the QRS complex with no PR interval
Sick Sinus Syndrome
- collection of arrhythmias due to dysfunctional SA node and unresponsive atrial/junctional foci
- marked by sinus bradycardia with no escape rhythm
- PSEUDO-sick sinus syndrome may be experienced in young, healthy ppl due to parasympathetic excess at rest
Bradycardia-Tachycardia Syndrome
-Patients with sick sinus syndrome may experience SVT mingled with their sinus bradycardia
1 degree AV Block
- prolongs AV nodal conduction
- PR interval that is lengthened ( >0.02 seconds) the same amount in every cycle
Wenckebach 2 degree AV Block
- some conduction gets through the AV node, some doesn’t
- occurs in the AV node itself, which is blocked more and more until it’s blocked completely for one cycle
- PR interval gets longer and longer until one QRS complex is dropped
- should have one less QRS than P wave
Mobitz 2nd Degree AV Block
- some conduction gets through the AV node, and some doesn’t
- occurs below the AV node
- series of normal P waves with no following QRS complexes for a few beats
- Should have P:QRS ratios of 3:1, 4:1, 5:1, etc.
3rd Degree (Complete) AV Block
- due to a complete blockade between atria and ventricles
- If block is in proximal AV node, then junctional foci can pace
- if block is below that (in the node or lower), then ventricular foci can pace
- AV dissociation: normal P wave pacing with a slower, completely separate QRS pacing
- If junctional foci pace, then QRS complexes with be normally-shaped and 40-60/min
- if ventricular foci pace, then QRS will be wide and 20-40/min
Right Bundle Branch Block
- block of the right bundle branch, delaying depolarization to the right ventricle
- joined QRS with two peaks, larger than 0.12 seconds (3 or more small squares), on the RIGHT chest leads (V1 and V2)
Left Bundle Branch Block
- due to complete block of the left bundle branch, delaying left ventricular depolarization
- joined QRS with two peaks, larger than 0.12seconds (3 or more small squares), on the LEFT chest leads (V5 and V6)
Intermittent Mobitz
- an occasional dropped QRS due to permanent BBB on one side and intermittent BBB on the other side
- remember, a mobitz block is an intermittent complete block, which you would have when one bundle branch is permanently blocked, and the other is intermittently (but completely) blocked
(-) QRS in lead I
(-) QRS in lead AVF
Extreme right axis deviation (re: proof on EKG)
(-) QRS in lead I
(+) QRS in lead AVF
(re: deviation)
right axis deviation (re: proof on EKG)
(+) QRS in lead I
(-) QRS in lead AVF
(re: deviation)
left axis deviation (re: proof on EKG)
(+) QRS in lead I
(+) QRS in lead AVF
(re: deviation)
“normal” axis (no deviation) (re: proof on EKG)
Isoelectric QRS in leads V3 and V4 (re: rotation)
normal (no rotation) (re: proof on EKG)
Isoelectric QRS in leads V1 and V2 (re: rotation)
rightward rotation (re: proof on EKG)
Isoelectric QRS in leads V5 and V6 (re: rotation)
leftward rotation (re: proof on EKG)
Wave that we look at for atrial hypertrophy
P wave (what do we look at this wave for?)
Lead that gives us the best information regarding atrial hypertrophy
Lead V1 (lead that gives us the best information for what?)
Specific type of P wave that’s present with atrial hypertrophy
diphasic P wave (present with what?)
Right Atrial Hypertrophy evidence on EKG
the initial portion of a diphasic P wave is larger
Left Atrial Hypertrophy evidence on EKG
terminal portion of a diphasic P wave is larger
Right Ventricular Hypertrophy evidence on EKG, including axis deviation and rotation
- large R wave in V1 (normally the R wave is small in this lead)
- right axis deviation
- rightward axis rotation
Left Ventricular Hypertrophy evidence on EKG, including axis deviation and rotation
- extra deep S wave in V1
- extra tall R wave in V5
- if depth of V1’s S wave and height of V5’s R wave add to be greater than 35mm, diagnose LVH
- T wave inversion and asymmetry (slow and gradual downslope with a rapid return to baseline)
Triad of a myocardial infarction
injury, ischemia, necrosis
Evidence of ischemia on EKG
- T wave inversion on leads V2-V6
- the T wave inversion is symmetrical
Evidence of injury on EKG
- ST segment elevation that will eventually return to baseline
- indicates ACUTE injury (check for this when there’s evidence of an infarct, too)
Evidence of a Subendocardial Infarction on EKG
depressed ST segment that’s either flat or down-sloping
Leads in which small “q” waves are normal
- lateral leads (I and AVL)
- inferior leads (II, III, AVF)
- chest leads V5 and V6
size parameters defining small “q” waves
< 1mm/one small square/0.04 seconds in duration
size parameters defining a significant Q wave
- at least 1mm wide, or
- amplitude 1/3 that of the total QRS complex
Anterior Infarction
- infarction on the anterior wall of the left ventricle
- Q waves in leads V1-V4
Antero-septal Infarction
- infarct that includes the septal portion of the left ventricle’s anterior wall
- Isolated Q waves in leads V1 and V2
Antero-Lateral Infarction
- infarction of the more lateral portion of the left ventricle’s anterior wall
- isolated Q waves in leads V3 and V4
Lateral Infarct
- infarction that involves the lateral portion of the left ventricle
- Q waves in the lateral leads (I and AVL)
Inferior Infarct
- AKA “diaphragmatic infarct”
- infarction that includes the inferior wall of the left ventricle
- Q waves in the inferior leads (II, III, and AVF)
Acute Posterior Infarct
-infarction of the left ventricle’s posterior wall
-very large R wave in leads V1 and V2
-ST depression in V1 and V2
(remember, this is exactly opposite from the evidence of an anterior infarct)
“tests” performed on an EKG strip when acute posterior infarct is suspected
- reversed transillumination test
- mirror test
coronary artery occluded in a lateral infarction
circumflex branch of the left coronary (occlusion causes what infarction?)
coronary occluded in an anterior infarction
anterior descending branch of the left coronary artery (occlusion causes what infarction?)
coronary artery occluded in a posterior infarction
right coronary artery (occlusion causes what infarction?)
coronary artery occluded in an inferior infarction
- either left or right coronary, depending on which is dominant
- right is more commonly dominant
- (occlusion causes what infarction?)
Ventricular conduction system components whose blood is delivered by the right coronary artery
- (delivery of blood by what coronary artery?)
- AV node
- Bundle of His
- variable twig sent to the posterior division of the left bundle branch
Ventricular conduction system components whose blood is delivered by the anterior descending branch of the left coronary artery
- (blood supply delivered by what coronary artery?)
- right bundle branch
- anterior division of the left bundle branch
- variable twig sent to the posterior division of the left bundle branch
True or False: If you have more P waves than QRS complexes then there is an AV block present.
True
In regards to AV Blocks, if the PR interval is constant then what type of Block is present?
2deg Mobitz
With AV Blocks, if the PR interval is not constant but the R-R intervals are constant then the block present is:
3deg AV Block
This type of AV Block has inconsistent PR intervals as well as inconstant R-R intervals.
2deg Wenckenbach
The QT interval should be what percentage of the cardiac cycle?
less than or equal to 40%
How can you calculate the exact HR on EKG?
1500 divided by the number of small boxes between R waves
What are causes of atrial and junctional foci irritability?
Adrenergic substances
What are causes of ventricular foci irritability?
Hypoxia, Hypokalemia, Pathologic process
