Ventricular Rhythms & Bundle Branch Blocks Flashcards
What is a Bundle Branch Block (BBB)?
An intermittent or permanent disruption in impulse conduction from the bundle of His through the right and left bundle branch to the Purkinje fibers. Results in abnormal electrical pathway through the ventricles resulting in a wide QRS complex (>0.11sec)
The impulse for the rhythm is still originating above the ventricles (i.e. sinus rhythms, atrial rhythms, junctional rhythms) but is forced to take an alternative pathway through the ventricles due to a disruption in the ventricular conduction pathway.
Supraventricular activity (like a P wave) followed by a wide QRS
Follows the pattern of another rhythm with the exception of a wide QRS
What are possible causes of a bundle branch block?
CAD
Cardiomyopathy
Myocardial Infarction
Heart Failure
Hypertension
Myocarditis
Cardiac Surgery
What is the treatment for a bundle branch block?
Depends upon the circumstances
New BBB may signal an acute MI which is treated with PCI
May require a pacemaker
What are the attributes of a premature ventricular complex
Rhythm -A beat or complex not a rhythm (alone or in pairs)
Pacemaker Site - Irritable site in the ventricles before SA node is ready to fire, early beat
Rate - Depends on underlying rhythm
P waves - None prior to PVC
PR interval - None
QRS complex- Wide, shape depends on irritable site
What is the name for a single PVC?
A singlet, isolated
What is the name given to two PVCs in a row?
A pair or couplet
What is a run?
anytime there are 3 or more abnormal beats in a row,
it must be interpreted as a separate rhythm. For example, “a 3-beat run of ventricular tachycardia” instead of a “run of PVCs”
What is it called when PVCs all have the same shape or appear to be originating from the same place in the ventricles
Monomorphic, uniform
What is it called when PVCs have different shapes or appear to be originating from different irritable sites in the ventricles
Polymorphic, multiform
What is bigeminy?
Every second or every other beat is a PVC
What is trigeminy?
When every third beat is a PVC
What is quadreminy?
Every 4th beat is a PVC
What is the difference between PVCs and escape beats?
PVCs are early, escape beats are late or come after the next expected beat
What is an escape beat?
An escape beat is a protective mechanism to prevent further slowing, or in other words, the “back-up pacemaker” is kicking in
What is a ventricular escape rhythm?
A ventricular escape rhythm (also known as idioventricular rhythm) occurs when 3+ ventricular escape beats occur in a row
What are the Hs and Ts (reversible causes of pulseless rhythm)?
Hypoxia
Hypotension
Hypo/hyperkalemia
Hydrogen ion (acidosis)
Hypothermia
Toxins
Tamponade
Tension pneumothorax
Thrombosis, pulmonary (PE)
Thrombosis, coronary (MI)
What is Pulseless Electrical Activity (PEA)?
An organized cardiac rhythm (except for VT or VF) but there is no myocardial muscle activity or pulse
Cause and treatment is the same as asystole
Poor prognosis unless the cause is quickly identified
How are pulseless rhythms treated?
Treatment of pulseless rhythms:
• Call a code
• Start CPR
• Identify and treat underlying cause
(H’s and T’s)
VT or VF:
• Defibrillation
• Epinephrine 1mg IVP q3-5mins
• Amiodarone 300mg IVP
PEA or Asystole:
• Epinephrine 1mg IVP q3-5mins
What is asystole?
Absence of ventricular electrical activity
NO PULSE
NO CARDIAC OUTPUT
What is the treatment for asystole?
CPR and Epinephrine IVP q3-5mins
Treat underlying cause
