Atrial Arryhtymias Flashcards
What is an ectopic pacemaker?
- Any pacemaker that is not the SA node
*results can be an ectopic (early or late) beat or ectopic rhythm (change in rhythm)
What are the 3 mechanisms for causing an ectopic beat?
- Altered Automaticity
*irritable area of the heart
* caused by hypoxia, the myocytes dont like to be w/o o2 - Triggered activity
*early beat that lands on the t-wave and trigger a new rhythm - Re-entry (mc)
*feeback loop involves the AV node
What are atrial arrhythmias?
- Originate from ectopic sites in the atria
- Ectopic P waves have different morphology than NSR p-waves (look at the p-wave)
What may be present in slower atrial rhythms?
- P wave may be small, pointed, upright
- May be small, barely visible
- May be inverted
*the ectopic Foci beat is going away from the positive pole)
What may be present in the faster atrial rhythms?
- P-onT (P waves bunched into the t-waves)
- Appears in a Sawtooth pattern (atrial flutter)
- As a wavy baseline (A-fib, heart is just quivering)
What are Premature Atrial Contraction (PACs)
- Early beat originating from ectopic site in atrium (outside SA node but still in the atria)
- Interrupts BR (BR is usually sinus)
- Can be single Foci (Same P-wave) or multiple Foci (different P-waves)
What are the characteristics of a PACs?
- Premature, abnormal P wave
- Premature QRS following
- Followed by a pause
Why do PACs happen
- The automaticity focus in the atria may become irritable and fire an impulse
*caused by adrenergic substances (causes fight or flight)
What are Bigeminy or Quadrigeminy?
Form of group beating
*Bi: normal, PAC, normal, PAC, normal, PAC
*Quad: Normal,normal, normal, PAC, normal, normal, normal, PAC
What is an atrial escape beat
- Ectopic atrial beat occurring late
- In order for this to happen there MUST be FAILURE of the SA node to initiate an impulse ORR the impulse is unable to leave the SA node
What does failure to initiate an impulse and failure to leave SA node mean?
Fail to initiate impulse: sinus arrest
Fail to leave SA node: Various
*Sinus block
*Nonconducted PAC
*Moritz type
What is a non-conducted PAC
- Ectopic atrial focus finds AV node refractory meaning
*impulse cannot get to the ventricles - Premature abnormal P wave NOT followed by QRS
*P-On-T - Pause is usually non-compensatory
What is the difference between a sinus arrest/block and a non-conducted PAC?
Sinus arrest/block:
1. Sudden pause in BR
2. No P wave present
3. T-wave contour is unchanged during pause
*no p-waves to distort T wave
Non-conducted PAC
1. Sudden pause in BR
2. Abnl, premature P waves present
*buried in T-wave
3. T- wave contour is changed during pause
What is paroxysmal atrial tachycardia? (SVT)
- Ectopic pacemaker in atria producing a rapid, regular atrial rhythm
*between 140-250 bpm - 3 or more conserve PACs at a rate of 140-250= Atrial tachycardia
- P waves are abnl and difficult to identify
What is the treatment for PAT/SVT? (Stable)
Depends on if the patient is stable or unstable
Stable:
1. Vagal maneuvers
2. Adenosine Rapid IVP
*6mg, repeat with 12mg if no response
