Arrhythmias

Question 1

AV blocks (general)

Answer 1

• slowed conduction from atria to ventricles
• prolonged PR interval
• bradycardia, fatigue, dizziness, syncope
• LYME disease
• caused by drugs, increased vagal tone, fibrosis/sclerosis of conduction system

Question 2

1st degree AV block

Answer 2

• block in AV node
• prolonged PR
• 1p : 1 QRS
• caused by B blockers, CCBs, trained athletes (slowed AV node conduction)

Question 3

2nd degree AV block, Mobitz 1

Answer 3

WENKEBACH

• block in AV node
• progressive PR prolongation
• RR interval variable
• caused by B blockers, CCBs, trained athletes (slowed AV node conduction)

Question 4

2nd degree AV block, Mobitz 2

Answer 4

• block in His-Purkinje sys
• constant PR
• spontaneous loss of AV conduction
• usually symptomatic: dizziness, syncope
• often seen with BBB (wide QRS)

Question 5

3rd degree AV block

Answer 5

• block in His-Purkinje system
• regular RR intervals
• p is completely unrelated to QRS
• dizziness, bradycardia, fatigue, syncope
• Tx: pacemaker

Question 6

RBBB

Answer 6

• wide QRS
• normal PR interval
• positive V1
• RsR’ (rabbit ears)

Question 7

LBBB

Answer 7

• wide QRS
• normal PR interval
• negative V1

Question 8

afib

Answer 8

• irregularly irregular
• no p waves
• depolarizations all over atria
• triggered by binge drinking, high catecholamines
• Tx: slow AV node conduction (BB, CCB), restore sinus rhythm (AA meds, cardiovert), ANTICOAGULATION

Question 9

atrial flutter

Answer 9

• saw tooth EKG
• impulse in circuit around atrium
• dizziness, fatigue, palpitations
• Tx: rate/rhythm control, cardioversion, anticoagulation

Question 10

AVNRT

Answer 10

• most common cause of PSVT
• dual AV nodal pathways
• fast pathway w/ long refractory
• slow pathway w/ short refractory
• cancel out in sinus rhythm
• problem if premature atrial contraction, starts circuit
• Tx: carotid massage, vagal maneuvers, adenosine, BBs, CCBs

Question 11

AVRT

Answer 11

-bypass tract (AV node not involved)
-orthodromic (most common) or antidromic (uncommon, wide QRS), or both (WPW)
-ventricular depolarization before AV nodal impulse
-retrograde p wave (inverted, after QRS)
-narrow QRS
-short PR
Tx: ablation

Question 12

WPW

Answer 12

• type of AVRT
• dual activation of normal method (slowed AV) + bypass tract (fast)
• delta wave: slurred upstart due to fusion of both waves
• short PR
• tachycardia, syncope
• if also a fib, then life threatening