Page 199 - Critical Care Nursing Demystified

184 CRITICAL CARE NURSING DeMYSTIFIED

NURSING ALERT

Frequent PACs should not be ignored. They are a red-light warning that PAT can
soon occur.

Paroxysmal Atrial Tachycardia (PAT) and Atrial Tachycardia
Paroxysmal atrial tachycardia occurs when a very irritable and cranky focus in
the atrium takes over as the pacemaker of the heart. If the rhythm starts
abruptly and ends just as suddenly, it is paroxysmal; if the rhythm is sustained
and does not break, it is atrial tachycardia. Either way, it strains the heart by
increasing oxygen and decreasing diastolic filling time. Diastolic filling time is
important; it is here that the atria fill the ventricles. If the diastolic filling time
is decreased due to a fast tachy rhythm, there is a decrease in atrial kick, which
comprises 20% of the cardiac output.
• RATE: Atrial/ventricular rates are very fast; usually around 180 to 220.
• RHYTHM: Very regular. PACs can herald the onset of PAT.
• CONDUCTION: PRI sometimes is very short with P waves being difficult Downloaded by [ Faculty of Nursing, Chiangmai University 5.62.158.117] at [07/18/16]. Copyright © McGraw-Hill Global Education Holdings, LLC. Not to be redistributed or modified in any way without permission.
to see. The QTI can be short as this is a tachy dysrhythmia.

Atrial Flutter
Atrial flutter is a sustained, regular rhythm where the atrial tissue is the pace-
maker of the heart. The rates are very fast but the P waves are each countable.
However, since they are in the 200 to 400s, the ventricles can not beat that fast,
so there are sometimes two, three, or four atrial beats to one ventricular beat. The
ventricles just can not keep up with all of those multiple regular P waves.

• RATE: Atrial rate – 200 to 400 beats per minute. The configuration of the
P waves is like a sawtooth pattern and are called flutter waves. The big
difference between atrial flutter and fibrillation is the countable P waves.
In atrial flutter you can count each and every P wave as they fall in a very
regular pattern.
Ventricular rate – 2:1 (2 Ps to 1 QRS), 3:1 (3 Ps to 1 QRS), and 4:1 (4 Ps to
1 QRS) conductions, which can be very regular or erratic.
• RHYTHM: The P-to-P interval is regular and the R-to-R interval depends
on the ratio of Ps to QRS complexes (2:1; 3:1 etc.)
• CONDUCTION: Once the stimulus gets to the AV node, the conduction
times are usually regular.