Arrythmias Flashcards
What is an AV block?
a condition where there is slowed or blocked conduction from atria to ventricles
What can be noticed on a ECG with a AV block?
prolonged PR interval
non-conducted P wave (in severe blockages; doesnt result to a QRS complex)
AV blocks can cause what symptoms?
Bradycardia –> fatigue, dizziness, syncope (happen when many or all p waves are not conducted)
What is a treatment of AVB?
pacemaker
T or F: AV node disease is more dangerous thant HIS-Purkinje disease
F:
HIS-Purkinje disease bc:
does not improve with sympathetic activation an dprogress to total heart block and requires a pacemaker
What are the 4 types of AV blocks and their associated ECG characteristics?
Type 1:
- prolonged PR interval
- all p-waves conducted
- usually the AV node
- causes: beta blockers, calcium channel blockers, athletes (cuz high parasymp tone at rest)
Type 2:
- some p-waves conducted
- sub-types:
- -> Mobitz 1 (Wenckebach)
- AV node block
- progressive PR elongation to dropped beat (no conduction)
- grouped beating (group of PQRS separated with no beat)
- RR intervals not regular (but irregular regular)
causes: similar to type 1 - -> Mobitz 2
- usually in HIS-Purkinje system
- usually associated with bundle branch block (leads to prolongued QRS interval)
- dizziness and syncope (often symptomatic)
- absence of PR elongation with missed conduction
Type 3:
- no impulse from atria to ventricles
- usually in HIS-Purkinje system
- no conduction of electrical impulses from atria
- RR intervals are regular
T or F: lyme disease can cause AV blocks
T via carditis
What happens in ventricular tachycardia?
dissociation of AV in the absence of heart block
-p-waves are still present
What is escape rhythm?
SA cannot send impulses to ventricles and lower pacemaker deploarises the ventricles
What are the symptoms of escape rhythm?
very slow: dizziness, syncope, hypotension
less slow: fatigue, exercise intolerance (bc lower pacemaker are insensitive to sympathetic activation)
What are some causes of heart block?
Drugs:
- beta blockers, Ca channel blockers, digoxin
High vagal Tone
Fibrosis and sclerosis of conduction system
True or False: if one bundle branch is blocked it leads to AV block
False: both bundle need to be blocked to have AV block
one bundle block creates a normal PR interval but a prolongued QRS (bc will longer for one of the ventricles to depolarise)
How to distinguish left and right branch bundle blocks on ECGs?
Look at V1–> left has a downward QRS deflection
right has two R waves
What are some causes of bundle branch blocks?
- usually slowly progressive fibrosis/sclerosis (more common in older patients)
- LBBB –> prior MI, cardiomyopathy
- RBBB –> right heart failure
What is PSVT?
Paroxysmal Supraventricular Tachycardia
- intermittent tachycardia (greater than 100 bpm)
- sudden onset/offset
- electrical activity originates above ventricle
- produces narrow QRS complex
What are symptoms of PSVT?
sudden-onset palpitations
chest discomfort
What are causes of PSVT?
AVNRT (atrioventricular nodal reentrant tachycardia)
–> most common cause
more common in young women
there is a presence of dual AV nodal pathway (ie both slow (short RP can conduct faster rate) and fast (long RP) conduction pathways present)
–> requires a PAC [premature atrial contraction]
What are ECG features in AVNRT?
- retograde P waves (comes after the QRS complex bc of the short conduction pathway going retrogade)
What are the 3 main ways to reduce AV conduction in AVNRT?
- carotid massage
- -> press on carotid sinus –> stretch baroreceptors –> CNS think high BP –> increase vagal tone –> decrease AV node conduction
-vagal maneuvers
vasalva, breath holding, coughing, deep respirations, swallowing
- adenosine
What is the treatment for AVNRT?
beta blockers, verapamil/diltiazem
What is WPW?
Wolff-Parkinson White Syndrome:
- presence of accessory atrioventricular pathway (ie bundle of kent)
- -> bypasses the AV node
- causes pre-excitation (ie. ventricular depol. before AV nodal impulse)
- may lead to arrythmias
What are the 2 classic ECG findings in WPW?
- delta waves (additional wave between P and R –> pre-excitation)
- short PR
What are the 2 types of AVRT?
orthodromic –> normal AV node conduction followed by impulse going to accessory pathway
antidromic –> from bypass tract to AV node
-wide QRS complex
What is the difference between WPW pattern and syndrome?
pattern –> asymp, delta waves
syndrome –> tachycardias, palpitations, AVRT
What is the treatment of AVRT?
ablation of accessory pathway
