EKGs Flashcards
Features of an EKG – in order of what to read in
- Heart rate
- P wave
- Origin of the rhythm
- PR interval
- QRS duration
- QT interval
- QRS axis
- QRS voltage
- Precordial R wave progression
- Abnormal Q waves
- ST segment
- T wave
- U wave
- Electronic pacemaker
EKG rates – Large boxes order
300 150 100 75 60 50 43 37 33
BPM = 300/# of large boxes
EKG rate for tachycardias – Small boxes order counting down from 300
300 250 214 188 167 150
BPM = 1500/# of small boxes
Normal P wave duration?
P wave separates into 1st and 2nd halves, corresponding into right and left atrial activation (respectively).
0.08-0.11 seconds
Normal P wave axis
0-75 degrees
Normal P wave morphology:
Upright in which leads?
upright or biphasic which leads?
Upright in leads: I, II, aVF
Upright or Biphasic: III, aVL, V1, V2
P:QRS Relationships
P:QRS < 1 Differential?
P:QRS < 1: Junctional or ventricular premature complexes or rhythms (escape, accelerated, tachycardia)
P:QRS Relationships
P:QRS = 1 Differential if the P wave precedes QRS?
P wave precedes QRS
Sinus rhythm; ectopic atrial rhythm;
multifocal atrial tachycardia; wandering atrial pacemaker; SVT (sinus node reentry tachycardia, automatic atrial tachycardia); sinoatrial exit block, 2o; conducted APCs with any of the above
P:QRS Relationships
P:QRS = 1 Differential if the P wave follows QRS?
P wave follows QRS:
SVT (AV nodal reentry tachycardia, orthodromic SVT); junctional / ventricular
P:QRS Relationships
Differential if there are no P waves?
No P Waves:
Atrial fibrillation; atrial flutter; sinus arrest with
junctional or ventricular escape rhythm; SVT (AV nodal reentry tachycardia, AV reentry tachycardia), junctional tachycardia or VT with P wave buried in QRS; VF
Heart Rate < 100 bpm Narrow QRS (< 0.12 sec) - Regular R-R 1. Sinus P; rate 60-100? 2. Sinus P; rate < 60? 3. Nonsinus P; PR
- Sinus rhythm
- Sinus bradycardia
- Ectopic atrial rhythm
- Junctional or low atrial rhythm
- Atrial flutter, usually with 4:1 AV block
- Junctional rhythm
- Accelerated junctional rhythm
Heart Rate 0.16 seconds?
- Sinus and nonsinus P?
- Any regular rhythm with 2o/ 3o AV block or premature beats
- Fine or coarse baseline oscillations?
- Sawtooth flutter waves?
- P:QRS ratio > 1?
- P:QRS ratio
- Sinus arrhythmia
- Wandering atrial pacemaker
- 2nd or 3rd deg AV Block or premature beats
- Atrial fibrillation with slow ventricular response
- Atrial flutter, usually with variable AV block
- 2o or 3o AV block or blocked APCs
- Junctional or ventricular premature beats or escape rhythm
Heart Rate < 100 bpm Wide QRS (> or = to 0.12 seconds) 1. Sinus or nonsinus P? 2. No P; rate < 60? 3. No P; rate 60-100?
- Any supraventricular rhythm with a preexisting IVCD (e.g. bundle branch block) or aberrancy
- Idioventricular rhythm
- Accelerated idioventricular rhythm AV dissociation may be present
Heart Rate > 100 BPM Narrow QRS (< 0.12 sec) - Regular R-R 1. Sinus P? 2. Flutter waves? 3. No P? 4. Short R-P (R-P < 50% of R-R interval)? 5. Long R-P (R-P > 50% of R-R interval)?
- Sinus tachycardia
- Atrial flutter
- AV nodal reentrant tachycardia (AVNRT), junctional tachycardia
- AVNRT, orthodromic SVT (AVRT), atrial tachycardia with 1o AV block, junctional tachycardia with 1:1 retrograde atrial activation
- Atrial tachycardia, sinus node reentrant tachycardia, atypical AVNRT, orthodromic SVT with prolonged V-A conduction
Heart Rate > 100 BPM Narrow QRS - Irregular R-R 1. Nonsinus P; > 3 morphologies? 2. Fine or coarse baseline oscillations? 3. Flutter waves? 4. Any regular rhythm with 2o/3o AV block or premature beats
- Multifocal atrial tachycardia
- Atrial fibrillation
- Atrial flutter
- 2o/3o AV block or premature beats
Heart Rate > 100 BPM
Wide QRS (> or = to 0.12 seconds)
1. Sinus or nonsinus P?
2. No P; rate 100-110?
3. No P, rate 110-250?
4. Irregular, polymorphic, alternating polarity?
5. Chaotic irregular oscillations; no discrete QRS?
- Any regular or irregular supraventricular rhythm with a preexisting IVCD or aberrancy
- Accelerated idioventricular rhythm
- VT, SVT with aberrancy
- Torsade de Pointes
- Ventricular fibrillation
Describe method for identifying rate (BPM) for slow or irregular rhythms.
- Identify 3 second markers at top or bottom of ECG tracing
- Count # of QRS complexes that appear in 6 seconds
- Multiply by 10 to obtain BPM.
PR interval is beginning of P to first deflection of QRS. What does PR interval represent?
*Note: PR Interval and PR Segment are different. PR segment is usually discussed in elevation or depression; normal is isoelectric.
PR interval represents conduction time from onset of atrial depolarization to the onset of ventricular depolarization. It does not represent conduction from sinus node to atrium.
Give duration of the following.
- Normal PR interval
- Prolonged PR interval
- Short PR interval
- 0.12-0.20 seconds
- > 0.20 seconds
- <0.12 seconds
QRS duration represents duration of ventricular activation; measured from beginning to the end of the complex.
Give duration of the following.
- Normal QRS duration
- Increased QRS duration
- or = 0.10 seconds (marked prolongation >0.12 seconds)
QT interval represents duration of ventricular systole (ventricular depolarization and depolarization).
How is it measured?
QT interval varies inversely with heart rate, so QTc is usually determined. How do you calculate?
From beginning of QRS complex to the end of the T wave.
QTc = QT interval / square root of the preceding RR interval.
Give duration of the following.
- Normal QTc
- Prolonged QTc
- Short QTc
- 0.35-0.43 seconds for HR 60-100; normal QT should be 0.43 seconds
- Short QTc < 0.35 seconds (for HR 60-100)
QRS axis quiz
Lead I – aVF – Lead II
a. + +
b. + - +
c. + - -
d. - +
e. - -
a. Normal axis (0-90)
b. Normal variant (0 to -30)
c. Left axis deviation (-30 to -90)
d. Right axis deviation (>100)
e. Right superior axis (-90 to +180)
How is low voltage defined using QRS amplitude? Give total QRS amplitude for limb leads and precordial leads.
Total QRS amplitude (R+S) <10mm in all precordial leads.
Small Q waves (duration <0.03 seconds) are normal in most leads except?
aVR, V1-V3
Give locations and duration of abnormal Q waves.
- Any Q wave in leads V1-V3
- Q wave >0.02 seconds in leads I, II, aVL, aVF, V4-6
ST segment represents the interval between the end of ventricular depolarization and the beginning of depolarization. How is ST segment duration measured? Where do you compare for elevation or depression?
Segment between the end of the QRS and the beginning of the T wave.
Measure in comparison to the TP segment (end of T to beginning of P).
T wave represents the electrical forces generated from ventricular depolarization.
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What rhythm has the following features:
- Ventricular rate of 30-40
- QRS morphology similar to VPCs
- QRS complex occurs as a secondary phenomenon in response to decreased sinus impulse formation or conduction or high degree AV block
Ventricular escape beats or rhythm
What rhythm has the following features:
- Ventricular rate of 40-60
- QRS morphology similar to sinus/supraventricular impulse
- QRS complex occurs in response to decreased sinus impulse formation or conduction, or high-degree AV block; the atrial mechanism may be sinus rhythm, paroxysmal atrial tachycardia, atrial flutter, or atrial fibrillation?
AV junctional escape complex
What rhythm has the following features:
- Ventricular ectopic beats occur at a rate of 30-50 (but can range 20-400 per minute)
- VPCs show non-fixed coupling
- Fusion complexes may be present
- All interectopic intervals are a multiple of the shortest interectopic interval?
Ventricular parasystole
What rhythm has the following features:
- Regular ventricular rhythm at a rate of 60-110
- QRS morphology is similar to VPCs
- Ventricular capture complexes, fusion beats and AV dissociation are common?
Accelerated idioventricular rhythm
What EKG features suggest a possible Ostium secundum ASD (70% of all ASDs are due to this) and are a result of deficient tissue in the region of the fossa ovals?
- RSR’ or rSR’ complex with a QRS duration < 0.11 seconds in V1
- Incomplete RBBB
- Right axis deviation +/- RVH
- Right atrial abnormality (develops in 30%)
- AV Block (develops in <20%)
What EKG features suggest a diagnosis of hypothermia?
- sinus bradycardia with widening of QRS
- Prolongation of PR and QT intervals
- Osborne (“J”) waves which are late upright terminal deflections of the QRS complex (“camel hump” sign)
- Afib is common
- AV junctional, VT and VF may also occur
What rhythm has the following features:
- Non sinus P wave
- Rate 0.11?
Ectopic atrial rhythm
What rhythm has the following features:
- Rate /= 3 morphologies
- PR, RR and RP intervals vary?
Wandering atrial pacemaker
What rhythm has the following features:
- PP interval >1.6 - 2 seconds
- Resumption of sinus rhythm at a PP interval that is not a multiple of the basic sinus interval?
Sinus pause or arrest
