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Advanced Cardiac Life Support (ACLS) Certification Course

Stable And Unstable Tachycardia

Rules for Sinus Tachycardia

Figure 37

RegularityR-R intervals are regular, overall rhythm is regular.
RateThe rate is over 100 bpm but usually less than 150 bpm.
P WaveThere is one P wave in front of every QRS. The P waves appear uniform.
PR IntervalMeasures between 0.12 and 0.20 seconds in duration. PR interval is consistent.
QRS ComplexMeasures less than 0.12 seconds.

Table 15

Rules for Atrial Flutter

Figure 38

RegularityThe atrial rate is regular. The ventricular rate will usually be regular, but only if the AV node conducts the impulses in a consistent manner. Otherwise, the ventricular rate will be irregular.
RateThe atrial rate is normally between 250 to 350. Ventricular rate depends on conduction through the AV node to the ventricles.
P WaveThe P waves will be well defined and have a “sawtooth” pattern to them.
PR IntervalDue to the unusual configuration of P waves, the interval is not measured with atrial flutter.
QRS ComplexQRS measures less than 0.12 seconds.

Table 16

Rules for Atrial Fibrillation (A-Fib) Irregular Narrow Complex Tachycardia

Figure 39

RegularityThe R-R intervals are irregular; therefore, overall rhythm is irregularly irregular. The ventricles conduct from different atrial foci causing the irregularity.
RateAtrial rate usually exceeds 350. If the ventricular rate is between 60 and 100 bpm, this is known as “controlled” A-Fib. If the ventricular rate is more than 100, it is considered A-Fib with Rapid Ventricular Response (RVR), also known as uncontrolled A-Fib.
P WaveDue to the atria firing so rapidly from multiple foci, there are no obvious P waves in the rhythm. The baseline appears chaotic because the atria are fibrillating, therefore no P waves are produced.
PR IntervalBecause there are no P waves, PR interval cannot be measured.
QRS ComplexQRS measures less than 0.12 seconds.

Table 17