Fall Quiz 2 Flashcards
What is the difference between a compensatory and non compensatory premature beat?
A compensatory premature beat will have QRS complexes that march out evenly before and after the pause.
What is a premature beat?
When an irritable ectopic focus fires prematurely.
What is an escape beat?
When the SA node doesn’t fire at its regular interval and an ectopic focus fires.
What is a reentry circuit?
A group of cardiac cells that depolarize in a circular pattern that is rapid and repetitive.
What is the underlying mechanism of most tachydysrhytmias?
Reentry circuits
What are the 2 types of reentry circuits?
Macroentry & Microentry
This refers to the amount of tissue that is affected by the circuit.
List the 3 conditions necessary to establish a reentry circuit.
- Two separate parallel paths of impulse conduction.
- Slowed conduction or complete unidirectional block in one of the pathways.
- The right timing of the absolute refractory period.
What is Wolf Parkinson White Syndrome? (WPW)
A macroreentry pathway where an accessory pathway provides secondary access to the ventricles.
List 6 types of Atrial Rhythms.
W: Wandering atrial pacemaker (WAP) E: Ectopic atrial tachycardia (EAT) A: Atrial Fibrillation (AFib) P: Premature atrial contraction (PAC) M: Multifocal atrial tachycardia (MAT) A: Atrial Flutter
Explain WAP
- Regular to irregularly irregular
- Wandering Atrial Pacemaker
- Pacemaker shifts between multiple foci (impulse origins)
- must have at least 3 different p-wave morphologies
- normal rate (60-100)
- normal QRS (less than 0.12)
Explain MAT rhythm.
- Regular to irregularly irregular
- Multifocal Atrial Tachycardia
- Tachycardic version of WAP
- 3 different pwave morphologies
- Less common than, and easy to confuse with AFib
- look for inverted pwaves to differentiate from AFib
Explain PAC rhythm.
- Premature Atrial Contraction
- Results from premature discharge of an ectopic atrial focus.
- characterized by a premature abnormal pwave.
- pwave may be buried in twave.
List 3 causes of PAC
Caffeine
Sympathomimetics
Hypoxia
What is a nonconducted PAC
It is a premature atrial contraction from an ectopic focus that is not transmitted through the AV node, resulting in a premature pwave with no corresponding QRS.
Explain EAT rhythm.
- Ectopic Atrial Tachycardia
- regular rhythm
- results from increased automaticity from an ectopic atrial focus or microreentry circuit.
Explain AFib.
- Atrial fibrillation
- caused by many irritable atrial foci firing at once, causing chaos.
- only some impulses are transmitted through the AV node resulting in irregularly irregular rhythm.
- PRI: non-existent
- QRS: <0.12
List some etiology of AFib.
- Atrial enlargement
- Age
- Pericarditis
- Coronary artery disease
- MI
- hypertension
- Alcohol abuse
List 2 problems associated with chronic AFib.
- Reduced cardiac output
* blood clots formed in the atria can lead to embolism or stroke
Explain Atrial Flutter
- rapid discharge of single ectopic focus causing atrial rate of 250-500 (usually 300)
- usually a regular rhythm
- is an example of a macro-reentry circuit
- rare - usually converts on its own.
Name the 4 junctional rhythms.
PJC: Premature Junctional Contraction
Junctional rhythm
Accelerated junctional rhythm
Junctional tachycardia