Ventricular Arrhythmias And BBB Flashcards
Where do SUPRAventricular rhythms send their impulse to, and what is the QRS complex characteristics?
- Send impulse through AV node and into the conduction system
- Narrow QRS duration
Where do ventricular rhythms originate from, and what is the QRS complex characteristics?
- Originate below the bundle of HIS or the ventricular myocytes
*There will be lower conduction
*flows in retrograde fashion - Wide QRS duration
*>0.12
What is the major characteristics of Ventricular Arrhythmias?
- There will be changes in ST segment and T waves
*they will slope in the opposite direction of the main QRS deflection - Ventricular repolarization is also abnormal
What are the different types of ventricular arrhythmias?
- Premature ventricular contractions (PVCs)
- Ventricular Tachycardia (VT)
- Ventricular Fibrillation (VF)
- Idioventricular rhythm
- Accelerated idioventricular rhythm
- Ventricular standstills (asystole)
Where do PVC arise from?
- Below the bundle of HIS in the ventricle
What are the PVC characteristics (QRS)?
- QRS is premature
- QRS is wide >0.12
- QRS morphology is different from QRS in underlying rhythm
What are the PVC characteristics (P-wave)?
- Sinus (BR)
*can be obscured within PVC
*can appear just before or in the ST segment of T wave
What are the PVC characteristics (ST segment and T wave)?
- ST segment and T wave slope in the opposite direction from the main QRS
What are the patterns of then PVCs?
- Every other beat = Bigeminy
- Every third beat = trigeminal pattern
- Every fourth beat = quadrigmeinal pattern
- Pairs = couplets
- Runs = 3 or more PVCs in a run constitutes a pattern
What are the PVC rhythms that have more >3 PVCs in a row?
- Idioventricular rhythm
*30-45 beats per minute - Accelerated idioventricular rhythm
*40-100 beats per minute - Ventricular tachycardia
*140-250 beats per minute
What are the different type of morphology a PVC could have?
- Unifocal
- Multifocal
What is a Unifocal PVC?
- Originates from a single focus
- The PVC look identical in the same lead
What is a Multifocal PVC?
- Different morphologies in different leads
- The PVCs look different (arise from different foci)
What is an interpolated PVC?
- PVC occurring between beats that does not disturb underlying rhythm
What is a R-On-T PVC?
- PVC falling on the downslope of preceding T wave
*may precipitate a malignant rhythm
Why do ventricular escape beats happen?
- The sinus node fails to produce an impulse AND
- Junctional tissue must fail to generate an impulse THEN
- The ventricular pacemaker then fires
What is the rate and rhythm of ventricular tachycardia?
Rate = 140-250bpm
Rhythm = regular
*can occur in short runs or as continuous rhythms
What are the ST segment and T wave characteristics of Ventricular Tachycardia
- They both slope in the opposite direction of the normal QRS complexes
What is the rate of ventricular flutter?
Rate = >250bpm
*looks like v-tach except for the rate
*there is no cardiac output
What is the difference between “non-sustained” and “sustained” VT
Non-sustained = VT lasts <30secs
Sustained = VT last >30secs
*life-threatening
What do you call VT if there are 3 or more CONSECUTIVE PVCs
Run/burst of nonsustained VT
What is Torsades DE Pointe?
- Polymorphic ventricular tachycardia
*the QRS complexes gradually gets narrow and wider
*There will be varying amplitudes of the QRS complexes
What is the treatment for Torsades De Pointe?
- Magnesium
- Defibrillation
What is the difference between course VF and Fine VF?
Course
1. Usually more irregular
2. More of a recent onset
Fine
1. resembles asystole
2. Check multiple leads
3. Will progress to asystole without treatment
What is the treatment for V-Fib
- CPR
- Defibrillation
What is the rate and rhythm of “idioventricular” rhythm
Rate = 30-40bpm (sometimes less)
Rhythm = regular
What are the P-wave characteristics of Idioventricular rhythm?
Absent
What is the PR interval duration of idioventricular rhythm?
- NA
What is the QRS duration for Idioventricular rhythm?
- Wide >0.12
What is the rate and rhythm of Accelerated Idioventricular rhythm?
Rate = 40-100bpm
Rhythm = regular
What is the P-wave characteristics and PR duration of Accelerated Idioventricular rhythms?
P-waves= Absent
PR = NA
What is the QRS duration for Accelerated Idioventricular Rhythms
Wide >0.12secs
What is ventricular standstill?
- Absence of electrical activity in ventricles
*No QRS complexes
What are the two presentations of ventricular standstill? (Asystole)
- P-waves with no QRS complexes
- Straight line
What is a BBB?
- A BBB is caused by a block in right or left bundle branch
*The depolarization to the ventricles will be delayed
What causes the R R’
- The ventricles are contracting asynchronously so
- One ventricle depolarizes slightly later than the other
- Which causes two “joined QRS”
If there is a BBB what must happen next?
Need to determine if it is a right or left BBB
*obtain a 12 lead EKG
Which leads will show a Right BBB?
V1
V2
*will have a more prominent R R’
What leads show a Left BBB?
V5
V6
*less prominent R R’ (depolarization of the left ventricle)
What is the rate and rhythm of a BBB?
Rhythm = regular
Rate = that of the underlying rhythm (sinus)
What is the P-wave characteristics and PR duration for BBB?
P= Sinus
PR = normal (0.12-0.20)
What is the QRS duration for BBB?
Wide
Can vector and hypertrophy be determined accurately in the presence of a BBB?
NO
What are capture and fusion beats?
BOTH HAPPEN DURING V-tach
Capture: ventricular conduction system is receptive during V-tach and will produce a normal appearing QRS complex
Fusion: Blending of a normal QRS with a PVC like complexes
