Junctional Rhythms and Heart Blocks Flashcards
What are the 6 mentioned causes of Junctional Rhythms?
1) Acute Coronary Syndromes (MI) or damage to AV node
2) Valvular Diseases
3) Hypoxia (i.e., suctioning)
4) ⬆ Parasympathetic stimulation
5) Meds (i.e., digoxin, beta blockers, and CCBs)
6) Pacemaker Failure
What is a Junctional Rhythm? What is its intrinsic rate and is it regular or irregular?
Junctional Rhythm occur when the AV node, instead of the Sinus Node, becomes the pacemaker. Rate is 40-60 bpm and regular.
What is the biggest clue to identifying a Junctional Rhythm?
An inverted P-wave. Can be before, during (hidden), or after the QRS complex.
When you see an arrhythmia with an inverted Pwave following the QRS complex, you know that rhythm originated in the AV Junction. But if the inverted Pwave precedes the QRS complex, how can you determine if it originated in the Atria or AV Junction?
By the PRI - If the impulse originated in the Atria, the impulse will be normal (0.12 to 0.20 secs).
If the impulse originated in the AV Junction, the PRI will be less than 0.12 secs.
What is the difference between Junctional Tachycardia and Accelerated Junctional Rhythm?
1) Accelerated Junctional Rhythm - 60 to 100 bpm
2) Junctional Tachycardia - 100 to 180 bpm
The 4 following arrhythmias may be regular and not may not have Pwaves and therefore may not be discernable from each other. When they are indiscernable, they arrhythmia is referred to broadly as SVT, what are the rates of the following SVTs:
1) Sinus Tachycardia
2) Atrial Tachycardia
3) Atrial Flutter
4) Junctional Tachycardia
1) Sinus Tachycardia - 100 to 160 bpm
2) Atrial Tachycardia - 150 to 250 bpm
3) Atrial Flutter - 150 to 250 bpm
4) Junctional Tachycardia - 100 to 180 bpm
How can you distinguish between a PAC, PJC, and PVC?
1) PAC - Pwave present and QRS is normal or < 0.12 secs.
2) PJC - Pwave inverted or absent and QRS is normal or < 0.12 secs.
3) PVC - No Pwave and QRS is wide and abnormal or > 0.12 secs.
Describe a First-Degree Heart Block?
In a First-Degree Heart Block, there is something delaying the impulse in the AV Junction, causing the PRI to be abnormally long (greater than 0.20 secs).
What are the causes a First-Degree Heart Block? What are the SxS? And how is it treated?
1) Cause - Can occur without an underlying pathophysiology or can be caused by meds (i.e., BBs, CCBs, or digoxin).
2) Patient is usually asymptomatic
3) Only treated if symptoms related to bradycardia are present.
Describe a Second-Degree Type I Heart Block (aka Wenkebach).
Heart block characterized by gradual and progressive conduction delay through the AV node, resulting in every 4 or 5 impulses not being conducted.
What are the causes of a Second-Degree Type I Heart Block? What are the SxS? And how is it treated?
1) Causes - ⬆ Parasympathetic or Vagal tone, ischemia, or meds (i.e., BBs, CCBs, and digoxin).
2) SxS related to bradycardia (chest discomfort, Dyspnea and hypotension).
3) If the patient has symptomatic bradycardia, Tx with atropine or transcutaneous pacing is indicated.
Describe a Second-Degree Type II Heart Block.
A Second-Degree Type II Heart Block occurs when only some of the atrial impulses are conducted through the AV node into the ventricles resulting in more P-waves than QRS complexes.
What are the causes of a Second-Degree Type II Heart Block? What are the SxS? And how is it treated?
1) Caused by ischemia usually due to blockage of the Left Coronary Artery.
2) SxS are related to bradycardia and may include chest discomfort, dyspnea and hypotension.
3) If the patient has symptomatic bradycardia, Tx with atropine or transcutaneous pacing is indicated.
Describe a Third-Degree or Complete Heart Block.
A Third-Degree or Complete Heart Block occurs when no atrial impulses stimulate the heart. The ventricles will initiate its own impulse, in the absence of an atrial impulse, and beat independently at its own intrinsic rate (this is called AV dissociation),
What are the causes of a Third-Degree or Complete Heart Block? What are the SxS? And how is it treated?
1) Caused by injury to the conduction system, so that there is no conduction between the atria and the ventricles.
2) SxS are related to bradycardia and may include syncope, dyspnea, chest discomfort and angina, and hypotension.
3) If the patient has symptomatic bradycardia, Tx with atropine or transcutaneous pacing is indicated.
