Rhythm Interpretations

*Regularity:* Dependent on the regularity of the underlying rhythm. *Rate:* Dependent of the rate of the underlying rhythm. *P Wave:* 1 upright and uniform P Wave in front of every QRS Complex. *PRI:* Constant across the strip, always >0.20 second. *QRS:* Measures less than 0.12 second

Rules for 1st Degree Heart Block.

*Regularity:* -Atrial Rhythm *immeasurable*. -Ventricular Rhythm *irregularly irregular*. *Rate:* -Atrial Rate *immeasurable*(estimated >350 BPM). -Ventricular Rate < Atrial (AV Node blocks most impulses). -Ventricular Rate is *"Controlled" if <100 BPM & "Uncontrolled" if >100 BPM* *P Wave:* No Atrial depolarization = no discernible P Waves. *PRI:* Immeasurable without P Wave. *QRS:* Measures less than 0.12 second.

Rules for A-Fib:

*Regularity, Rate, P Wave, PRI, QRS:* There is NO ELECTRICAL ACTIVITY; only a straight line.

Rules for Asystole:

*Regularity:* Atrial rhythm *regular*. Ventricular rhythm *regular or irregular* (depending on AV Node conduction consistency). *Rate:* Atrial Rate *250-350 BPM*; Ventricular Rate *dependent* on ratio of impulses conducted through the Ventricles. *P Wave:* When Atria "flutter" they produce well-defined *Sawtooth P Waves*. *PRI:* Unable to measure due to flutter. *QRS:* Measures less than 0.12 second, but can be difficult to measure if flutter waves are concealed within the QRS complex.

Rules for Atrial Flutter:

*Regularity:* R-R intervals constant; Rhythm is regular. *Rate:* Atrial Rate = Ventricular Rate; Heart Rate usually 150-250 BPM. *P Wave:* 1 P Wave in front of every QRS Complex. P Wave configuration may be flattened or notched, & can be hidden in the T Wave of preceding beats. *PRI:* Measures 0.12-0.20 second & is constant across the strip. May be difficult to measure if P wave obscured by T Wave. *QRS:* Measures less than 0.12 second.

Rules for Atrial Tachycardia (which can become SVT):

Accelerated Junctional Rhythm.

Name the Rhythm: An irritable focus in the AV Junction speeds up (*slightly*) to override the SA Node for control of the heart. The Atria are depolarized via retrograde conduction. Conduction through the Ventricle is normal.

Junctional Tachycardia.

Name the Rhythm: An irritable focus in the AV Junction speeds up to tachycardic rates to override the SA Node for control of the heart. The Atria are depolarized via retrograde conduction. Conduction through the Ventricles is normal.

Idioventricular Rhythm (IVR).

Name the Rhythm: In the absence of a higher pacemaker, the Ventricles initiate a regular impulse at their inherent rate of 20-40 BPM.

Sinus Arrhythmia

Name the Rhythm: Sinus node is the pacemaker, but impulses are initiated in an irregular pattern. Rate increases on inspiration & decreases on expiration. Each impulse is conducted normally through the ventricles.

Type II 2nd-Degree Heart Block.

Name the Rhythm: The AV Node selectively conducts some beats while blocking others. Those that are not blocked are conducted through the Ventricles, though they may encounter a slight delay in the AV node. Once in the ventricles, conduction proceeds normally.

Wandering Pacemaker

Name the Rhythm: The Pacemaker site wanders between the Sinus Node, the Atria, and the AV Junction. Each beat originates from a different focus, but usually remains 60-100 BPM, sometimes slower. Each impulse is conducted normally through the ventricles.

Junctional Escape Rhythm.

Name the Rhythm: When higher pacemaker sites fail, the AV Junction is left with pacemaking responsibility. The Atria are depolarized via retrograde conduction. Ventricular conduction is normal.

Atrial Flutter.

Name the Rhythm: A single irritable focus within the Atria issues rapid, repetitive impulse. To protect the ventricles from receiving too many impulses, the AV node blocks some of the impulses from being conducted through the ventricles.

Premature Ventricular Complex (PVC).

Name the Rhythm: A single irritable focus within the ventricles that fires pre-maturely to initiate an Ectopic Complex.

Ventricular Fibrillation (V-Fib).

Name the Rhythm: Multiple foci in the Ventricles become irritable and generate uncoordinated, chaotic impulses that cause the heart to Fibrillate rather than contract.

Normal Sinus Rhythm (NSR)

Name the Rhythm: Sinus Node is the pacemaker, firing 60-100 times per minute. Each impulse conducts normally through the Ventricles.

Sinus Tachycardia

Name the Rhythm: Sinus Node is the pacemaker, firing greater than 100 times per minute. Each impulse is conducted normally through the ventricles.

Sinus Bradycardia

Name the Rhythm: Sinus Node is the pacemaker, firing less than 60 times per minute. Each impulse is conducted normally through the ventricles.

1st-Degree Heart Block.

Name the Rhythm: The AV Node holds each sinus impulse longer than normal before conducting it through the Ventricles. Each impulse is eventually conducted. Once into the Ventricles, conduction proceeds normally.

Atrial Fibrillation (A-Fib).

Name the Rhythm: The Atria are so irritable that a multitude of foci initiate impulses, causing the atria to depolarize repeatedly in a fibrillatory manner. The AV Node blocks most impulses, allowing only a limited number through the ventricles.

Asystole.

Name the Rhythm: The Heart has lost all electrical activity. There is no electrical pacemaker to initiate electrical flow.

Atrial Tachycardia

Name the Rhythm: The Pacemaker is a single irritable site within the atrium that fires rapidly and repetitively. Conduction through the Ventricles is normal.

Premature Junctional Complex.

Name the Rhythm: The Pacemaker is an irritable focus with the AV Junction that fires prematurely and produces a single Ectopic beat. The Atria are depolarized via retrograde conduction. Conduction through the Ventricles is normal.

Complete Heart Block (3rd-Degree).

Name the Rhythm: The block at the AV Node is Complete. Sinus impulses cannot penetrate the node and thus are not conducted to the Ventricles. An escape mechanism from either the Junction or the Ventricles will take over to pace the Ventricles. The Atria and Ventricles function in a totally dissociated fashion.

Premature Atrial Complex.

Name the Rhythm: The pacemaker is an irritable focus within the Atrium that fires prematurely and produces a single Ectopic beat. Each impulse is conducted normally through the Ventricles.

Type I 2nd-Degree Heart Block (Wenckeback).

Name the Rhythm: As the Sinus node initiates impulses, each one is delayed in the AV node a little longer than the preceding one, until one is eventually blocked completely. Those impulses that are conducted travel normally through the ventricles.

*Regularity:* Usually regular, though less reliable as the heart dies. *Rate:* Ventricular Rates are usually 20-40 BPM, but can drop below 20 BPM. *P Wave:* There are no P Waves in this arrhythmia. *PRI:* No PRI. *QRS:* Wide and bizarre, at least 0.12 second.

Rules for IVRs:

*Regularity:* R-R intervals constant; rhythm regular. *Rate:* Atrial Rate = Ventricular Rate; Rate will be tachycardic, but does not usually exceed 100-180 BPM. *P Wave:* May come before or after the QRS Complex, or be obscured by it. If visible it will be inverted. *PRI:* If P Wave precedes the QRS Complex, PRI is <0.12 second. If P wave is within or follows the QRS Complex, there is no PRI. *QRS:* Measures less than 0.12 second

Rules for Juntional Tachycardia:

*Regularity:* R-R intervals constant; rhythm regular. *Rate:* Atrial Rate = Ventricular Rate; Heart Rate is 60-100 BPM *P Wave:* 1 uniform P Wave in front of every QRS Complex. *PRI:* Measures 0.12-0.20 second & is constant across the strip. *QRS:* Measures less than 0.12 second

Rules for NSR:

*Regularity:* Underlying rhythms can be regular or irregular. The Ectopic PVC will interrupt the regularity of the underlying rhythm (unless the PVC is interpolated). *Rate:* Rate determined by underlying rhythm. PVC's are not usually included in the rate determination, as they do not usually produce a pulse. *P Wave:* The Ectopic is not preceded by a P Wave, though a dissociated P wave may be seen near the PVC. *PRI:* Since the Ectopic comes from a lower focus, there will be no PRI. *QRS:* The QRS Complex will be wide and bizarre, measuring at least 0.12 second. Configuration will differ from the underlying QRS complexes. T wave is frequently in the opposite direction from the QRS complex.

Rules for PVC:

*Regularity:* 1 Premature Ectopic Beat interrupts the regularity of the rhythm. R-R interval is irregular. *Rate:* overall rate depends on the rate of the underlying rhythm. *P Wave:* May come before or after the QRS Complex, or be obscured by it. If visible it will be inverted. *PRI:* If P Wave precedes the QRS Complex, PRI is <0.12 second. If P wave is within or follows the QRS Complex, there is no PRI. *QRS:* Measures less than 0.12 second.

Rules for Premature Junctional Complex:

*Regularity:* R-R intervals vary; rate changes with respiration. *Rate:* Atrial Rate = Ventricular Rate; Heart Rate usually 60-100 BPM, but can be slower. *P Wave:* 1 uniform P Wave in front of every QRS Complex. *PRI:* Measures 0.12-0.20 second & is constant across the strip. *QRS:* Measures less than 0.12 second.

Rules for Sinus Arrhythmia:

*Regularity:* R-R intervals constant; rhythm regular. *Rate:* Atrial Rate = Ventricular Rate; Heart Rate less than 60 BPM. *P Wave:* 1 uniform P Wave in front of every QRS Complex. *PRI:* Measures 0.12-0.20 second & is constant across the strip. *QRS:* Measures less than 0.12 second.

Rules for Sinus Bradycardia:

*Regularity:* R-R intervals constant; rhythm regular. *Rate:* Atrial Rate = Ventricular Rate; Heart Rate greater than 100 BPM (usually 100-160 BPM). *P Wave:* 1 uniform P Wave in front of every QRS Complex. *PRI:* Measures 0.12-0.20 second & is constant across the strip. *QRS:* Measures less than 0.12 second.

Rules for Sinus Tachycardia:

*Regularity:* If conduction ratio is consistent, R-R intervals are constant & rhythm regular. If conduction ration is inconsistent, R-R is irregular. *Rate:* Atrial Rate is normal, 60-100 BPM. Since many Atrial impulses are blocked, Ventricular Rate is usually bradycardic, <60 BPM (often 1/2, 1/3, or 1/4 of Atrial Rate). *P Wave:* P Waves are upright and uniform. There will always be more P Waves than QRS Complexes. *PRI:* On conducted beats measures it is constant across the strip, but may be > than 0.20 second. *QRS:* Measures less than 0.12 second

Rules for Type II 2nd-Degree Heart Block:

*Regularity:* No analyzable waves or complexes. Totally Chaotic Baseline. *Rate:* Immeasurable without discernable waves or complexes. *P Wave:* No discernible P Waves. *PRI:* No PRI. *QRS:* No discernible QRS Complexes.

Rules for V-Fib Rhythms.

*Regularity:* R-R intervals vary slightly as the pacemaker site changes; rhythm slightly irregular. *Rate:* Atrial Rate = Ventricular Rate; Heart Rate usually 60-100 BPM, but can be slower. *P Wave:* Morphology changes as the pacemaker site changes; 1 P Wave in front of every QRS Complex, but some may be difficult to see. *PRI:* Varies slightly as the pacemaker sight changes. Usually less than 0.20 second, some less than 0.12 second. *QRS:* Measures less than 0.12 second.

Rules for Wandering Pacemaker:

*Regularity:* Both the Atrial and Ventricular foci are firing regularly, thus the P-P & R-R Intervals are regular. *Rate:* Atrial Rate is normal, 60-100 BPM. The Ventricular Rate will be slower. Junctional focus = Ventricular Rate 40-60 BPM. Ventricular focus = Ventricular Rate 20-40 BPM. *P Wave:* P Waves are upright and uniform. There are more P Waves than QRS Complexes. *PRI:* There is no PRI due to the block at the AV Node. P Waves have no relationship to QRS Complex, though they may occasionally be superimposed on the QRS complex. *QRS:* Junctional focus = PRI <0.12 second. Ventricular focus = PRI = or >0.12 second.

Rules for a Complete Heart Block Rhythm:

*Regularity:* R-R intervals constant; rhythm regular. *Rate:* Atrial Rate = Ventricular Rate; the inherent rate of the AV Junction is 40-60 BPM. *P Wave:* May come before or after the QRS Complex, or be obscured by it. If visible it will be inverted. *PRI:* If P Wave precedes the QRS Complex, PRI is <0.12 second. If P wave is within or follows the QRS Complex, there is no PRI. *QRS:* Measures less than 0.12 second

Rules for a Junctional Escape Rhythm:

*Regularity:* 1 Premature Ectopic Beat interrupts the regularity of the rhythm. *Rate:* overall rate depends on the rate of the underlying rhythm. *P Wave:* The Premature Ectopic Beat will have a P Wave which will be of a different morphology than those on the rest of the strip (flat, notched, etc...). P Wave may be hidden within the T wave of the preceding complex. *PRI:* Usually measures 0.12-0.20 second, but can be prolonged. The PRI of the ectopic beat will probably be different from the other complexes. *QRS:* Measures less than 0.12 second.

Rules for a Premature Atrial Complex.

*Regularity:* R-R intervals irregular in a pattern of grouped beating. *Rate:* Atrial Rate is normal, 60-100 BPM. Ventricular rate is usually <100 BPM due to some beats not conducting. *P Wave:* P Waves upright and uniform, but not all followed by QRS Complexes. *PRI:* Progressively longer until one P Wave is not followed by a QRS complex. After the blocked beat, the cycle restarts. *QRS:* Measures less than 0.12 second

Rules for a Type I 2nd-Degree Heart Block (Wenckeback) Rhythm:

*Regularity:* R-R intervals constant; rhythm regular. *Rate:* Atrial Rate = Ventricular Rate; Rate will be faster than the AV Junctions inherent rate, but not a true tachycardic range; 60-100 BPM. *P Wave:* May come before or after the QRS Complex, or be obscured by it. If visible it will be inverted. *PRI:* If P Wave precedes the QRS Complex, PRI is <0.12 second. If P wave is within or follows the QRS Complex, there is no PRI. *QRS:* Measures less than 0.12 second

Rules for an Accelerated Junctional Rhythm: