Atrial Rhythms

Atrial contraction pushes the last 1/3 of blood into the ventricles

P Wave

Premature beat (P wave) that occurs early before the next expected beat.  Must ID underlying rhythm, count rate, and name the premature beats.

• If the normal beat following the premature complex occurs before expected  
• (Distance is NOT the same)

• If normal beat following premature  complex occurs when expected  
• (Distance is the same)

P wave occurred too early. (AV junction is still  refractory) No QRS present & appears as a pause.  Differs from Sinus Pause, as a P wave is present or seen in preceding T wave.

If nonconducted P wave hidden in preceding T wave, it will change shape of T wave – adds amplitude or a “hump.”

2 PACs in a row (sequential)

• 3 or more sequential PACs 
• “paroxysmal atrial tachycardia” (PAT) or “paroxysmal supraventricular tachycardia” (PSVT)

• Bigeminy: every other beat is a PAC
• Trigeminy: every third beat is a PAC

P waves vary in size, shape, & direction across the rhythm strip.  Need to identify 3 different P wave shapes in the same lead to call the rhythm MFAR.

• –Sinus tachycardia (ST)
• –Atrial tachycardia (AT)
• –Supraventricular tachycardias (SVT)
• –Atrial flutter (A Flutter)
• –Atrial fibrillation (A Fib)

SVT can be called atrial tachycardia if a visible P wave (atrial activity) is present.

Describes an SVT that starts & stops suddenly.

Connects atria directly to the ventricles, completely bypassing normal conduction system.

"F" or "flutter" waves

An irritable atrial site depolarizes regularly at an extremely rapid rate (250-350 bpm). Results in waveforms that resemble the teeth of a saw or a picket fence.

• Multiple atrial ectopic sites initiate rapid impulses (350-600 bpm) which causes ineffectual atrial contraction or quiver (fibrillate).
• Results in subsequent decrease in CO, loss of “atrial kick”, & risk of clot formation.

ALWAYS IRREGULAR ventricular rhythm with normal QRS complex.  No identifiable P waves.