W3 D4 - ECG Junctional Rhythms

Question 1

What is the patho of all junctional rhythms?

Answer 1

Retrograde conduction
* conduction goes backwards towards the SA node

Absent P before QRS
* AV node sends an impulse to ventricles, avoids atria altogether
* narrow QRS

Inverted P wave before QRS
* travels UP to the SA node then down to the ventricles

Inverted P after QRS
* impulse goes down the ventricles then back up to the SA node

Inverted P during QRS; superimposed
* impulse moves up to SA node and down to ventricles at the same time
* QRS slightly wide

Question 2

How do you classify junctional rhythms?

Answer 2

Is the P wave inverted or absent prior to the QRS? = junctional!
* could be inverted, within or after QRS

Question 3

How do you classify a premature junctional complex (PJC)?

patho, causes, treatments

Answer 3

Early beat with inverted or absent P prior to QRS
* AV node sends an early impulse before the SA node

Causes
* CHF, inferior MI, electrolyte, caffeine, hypoxia

Treatments
* generally none, investigate

Question 4

How do you classify a junctional escape beat?

patho, causes, treatment

Answer 4

Late beat, inverted or absent P prior to QRS
* SA node failed to fire so the AV node initiated a beat to maintain CO
* delayed QRS

Causes
* CHF, hypothermia, suctioning, myocarditis
* slowing of SA node; severe brady, sinus pause, meds BB & CCB

Treatment
* investigate other causes

Question 5

How do you classify junctional escape rhythm?

patho, cause, treatment

Answer 5

Inverted or absent P prior to QRS, HR 40-60, reg rhythm
* the SA node is too slow so the AV node takes over but can only send impulses at a rate of 40-60 bpm
* below 40 would be junctional brady

Causes
* CHF, hyperkalemia, hypothermia, suctioning
* slowing of SA node; severe brady, sinus pause, BB, CCB

Treatments
*stable/asymptomatic *
* monitor and investigate

unstable/symptomatic
* atropine, dopamine, epinephrine, pacing

Question 6

How do you classify accelerated junctional rhythm?

patho, causes, treatment

Answer 6

Inverted or absent P prior to QRS, HR 60-100 bpm, reg rhythm
* AV node has altered automaticity and fires before the SA node
* 1st up to SA node then down to ventricles

Causes
* MI, CHF, electrolyte imbalance

Treatment
* usually asymptomatic
* investigate cause

Question 7

How do you classify junctional tachycardia?

patho, causes, treatment

Answer 7

Inverted or absent P prior to QRS, HR over 100 bpm, reg rhythm
* AV node has altered automaticity and fires before the SA node
* 1st up to SA node then down to ventricles

Causes
* MI, CHF, electrolyte imbalance, COPD

Treatment
stable
* vagal maneuvers
* adenosine, BB, CCB, amiodarone

unstable
* synchronized cardioversion

Question 8

Accelerated idioventricular escape rhythm vs. accel. junctional rhythm

Answer 8

Ventricular - wide & bizzare QRS
Junctional - narrow QRS

Question 9

How to differentiate atrial tachycardia and junctional tachycardia?

Answer 9

Use term supraventricular tachycardia SVT
* rhythm too fast to analyze
* when impulse orginates above the ventricles

Umbrella for ALL
* Atrial tach.
* A-flutter
* A-fib.
* Junctional tach.