IDENTIFY each one of the rhythms using the process of rhythm identification. I a
ID: 3476541 • Letter: I
Question
IDENTIFY each one of the rhythms using the process of rhythm identification. I am looking for what the name of the rhythm is.
NOTES: TO help identify rhythms using the process
Atrial Fibrillation:
Rate: Atrial usually 400-600 bpm, ventricular rate determined by AV blockade
Rhythm: Ventricular rhythm is irregularly irregular
P waves: No identifiable P waves
PR interval: Not measurable
QRS duration: .11 unless intraventricular conduction delay exists
Atrial Flutter:
Ectopic rhythm in which irritable focus fires regularly at a very rapid rate
Rate: Atrial rate 250-350; ventricular rate determined by AV junction
Rhythm: Atrial is regular, ventricular is regular or irregular depending on Av conduction/blockade
P waves: No identifiable P wave, saw-toothed flutter waves
QRS: .11 but may be wide if flutter waves are buried in QRS or intraventricular conduction delay exists
Wolff-Parkinson-White syndrome is common in patients with AVRT
Rate: Usually 60-100 if underlying rhythm is sinus
Rhythm: Regular unless associated with Afib
P waves: Normal unless associated with Afib
PR interval: If P waves are observed, .12
QRS: Wide, usually .12, slurred upstroke of QRS (delta wave) seen in more than one lead
AVNRT:
Rate: 150-250 (usually 180 – 200)
Rhythm: Ventricular rhythm is regular
P waves: Often hidden in QRS, negative P wave can be present, P wave can occur after QRS
PR interval: Not measurable because P waves are not seen before QRS
QRS duration: .11 unless intraventricular conduction delay exists
Atrial Tachycardia:
Rate: 100-250
Rhythm: Regular
P waves: Positive P precedes each QRS, P wave differ in shape from sinus P wave. Rapid rate makes it difficult to distinguish P waves from T waves
PR interval: May be shorter or longer than normal
QRS duration: .10 unless intraventricular conduction delay
Wandering Atrial Pacemaker:
Rate: Usually 60-100 bpm, >100 it is called multifocal atrial tachycardia
Rhythm: May be irregular
P waves: Size, shape, and direction may change from beat to beat. At least 3 different P wave configurations
PR interval: Variable
QRS duration: .11 unless intraventricular conduction delay exists
Premature atrial complex : PAC
Beat is premature (early)
Rhythm is usually regular with premature beats
Rate depends on underlying rhythm
P wave is premature, positive in lead II, one before each QRS unless not conducted, often differs in shape from sinus P wave
PR interval may be normal or prolonged
QRS usually .10 or less but may be wide if aberrantly conducted, may be absent in non-conducted P wave
Sinus and Atrial Rhythm Practice KIN 4334Explanation / Answer
The correct answer is Premature atrial complex : PAC
Beat is premature (early).
Rhythm is usually regular with premature beats
Rate depends on underlying rhythm
P wave is premature, positive in lead II, one before each QRS unless not conducted, often differs in shape from sinus P wave
PR interval may be normal or prolonged
QRS usually .10 or less but may be wide if aberrantly conducted, may be absent in non-conducted P wave
Explanation is given below.
Let us consider this to be a 10sec rhythm strip.
There are 7 QRS waves in the given ECG. One large box is 0.2 seconds. In the given figure, QRS interval is two small boxes. Normal QRS is 0.08 to 0.12 seconds.
5 small boxes is 0.2 seconds. So, 2 small boxes will be 0.08 seconds. So, QRS interval is normal.
Note that QRS signifies that this case is not Wolff-Parkinson-White syndrome.
Ventricular rate = number of QRS complexes in one minute = 7*6 = 42 bpm
Adult ventricular heart rate is normal if it ranges between 15-40bpm. So, ventricular rate is normal.
Atrial rate= number of P waves in one minute = 7*6 = 42bpm
AV node is usually only capable of generating a rhythm at <= 40-60bpm. So, this rate is also normal here.
So, this case is not atrial flutter or atrial fibrillation.
RR interval is constant; so, rhythm is regular. So, this case is not wandering atrial pacemaker.
Now, count the number of beats per minute. For this count the number of boxes between R-R interval. The number of boxes is 5 large and 2 small boxes = 27 small boxes.
This will equal to (0.2/5) *27 = 1.08 seconds
This implies (60/1.08) = 55.55 beats per minute. Note that normal heart rate is 50 to 100 beats per minute. So, this is low, but not abnormal. This case is not AVNRT and atrial tachycardia.