Atrial Rhythms Flashcards
(34 cards)
What are the atria?
thin walled, low pressure chambers that receive blood from the systemic circulation and lungs
What is atrial kick?
additional contribution of blood because of atrial contraction
What are atrial dysrhythmias?
reflections of abnormal electrical impulse formation and conduction in the atria
What do atrial dysrhythmias result from?
- altered automaticity
- triggered activity
- reentry
What is altered automaticity?
both normal pacemaker cells and myocardial working cels that fire and initiate impulses before a normal SA node impulse
What are the causes of altered automaticity?
- hypocalcemia
- ischemia
- imbalance of electrolytes
- drug toxicity
What is triggered activity?
when escape pacemaker and myocardial working cells fire more than once after stimulation by a single impulse
What does triggered activity cause?
atrial or ventricular beats that can occur alone, in pairs, in runs or as a sustained ectopic rhythm
What is reentry?
when an impulse returns to stimulate tissue that was previously depolarized
What three conditions does reentry require?
- a potential conduction circuit or circular conduction pathway
- a block within part of the circuit
- delayed conduction within the remainder of the circuit
What atrial rhythms are associated with reentry?
- atrial flutter
- AVNRT
- AVRT
True/False: most atrial dysrhythmias are life threatening and some may be associated with extremely slow ventricular rates
false: not life-threatening and fast rates
True/False: an excessively fast heart rate can lead to decreased cardiac output
true
What are premature atrial complexes (PACs)?
premature beats that originate in the atria
What patterns can premature beats occur in?
- couplet (two)
- bursts (three or more)
- bigeminy (every other)
- trigeminy (every third)
- quadrigeminy (every fourth)
When do PACs occur?
when an irritable site (i.e., focus) within the atria fires before the next SA node impulse is expected to fire
What kind of P wave and QRS complex does a PAC have?
- positive P wave
- normal QRS complex
How are PACs identified?
- early (premature) P waves
- positive (upright) P waves (in lead II) that differ in shape from sinus P waves
- early P waves that may or may not be followed by a QRS complex
Is a PAC an entire rhythm?
no, it is a single beat. therefore, you must identify the underlying rhythm and ectopic beats
What is a non-compensatory pause?
a delay during which the SA node resets its rhythm for the next beat. it is the period between the complex before and after a premature beat and is less than two normal R-R intervals?
What is a compensatory pause?
when the period between the complex before and after a premature beat and is the same as two normal R-R intervals
What causes PACs?
- acute coronary syndromes
- atrial enlargement
- digitalis toxicity
- electrolyte imbalance
- emotional stress
- heart failure
- hyperthyroidism
- mental and physical fatigue
- stimulants such as coffee, tobacco and cocaine
- valvular heart disease
What may PACs be the result of?
- altered automaticity
- reentry
Who do PACs very frequent occur in and what do they mean?
older adults - does not necessarily imply underlying cardiac disease
