Module 3: Cardiac Rhythm

Normal sinus rhythm

Impulse initiation: SA node

Rate: 60-100 beats/min

Rhythm: regular

P waves: uniform, upright

PR interval: 0.12-0.20 sec, constant

QRS: less than 0.14 sec

P/QRS Ratio: 1:1

Sinus bradycardia

Impulse initiation: SA node

Rate: less than 60/minute

Rhythm: regular

P waves: uniform, upright

PR interval: 0.12-0.20 sec, constant

QRS: less than 0.14 sec

P/QRS Ratio: 1:1

Sinus tachycardia

Impulse initiation: SA node

Rate: 101-180 beats/min

Rhythm: regular

P waves: uniform, upright, may be difficult to use

PR interval: 0.12-0.20 sec, constant

QRS: less than 0.14 sec

P/QRS Ratio: 1:1

Sinus arrhythmia

Impulse initiation: SA node

Rate: usually 60-100 beats/min, may be faster or slower

Rhythm: irregular, increases during inspiration, decreases during expiration

P waves: uniform, upright

PR interval: 0.12-0.20 sec, constant

QRS: less than 0.14

P/QRS Ratio: 1:1

Sinus pause

Generally the rhythm is normal sinus, but could happen with any cardiac rhythm.

Conduction from the SA to the AV is “paused” for one to several seconds until the bundle branches realize that there is not any SA conduction and attempts to reset itself.

Results in an overly charged contraction of the ventricles causing a “flutter” feeling to the patient

Normal sinus rhythm

rate 60-100, PR interval less than 0.20, QRS less than 0.14, everything is 1:1

Sinus bradycardia

rate less than 60 but everything else is normal

Sinus tachycardia

rate greater than 100 but everything else is normal

sinus arrhythmia

rate 60-100, PR interval less than 0.20, QRS less than 0.14, everything is 1:1, but the R to R distance varies

Sinus pause

all rules for sinus rhythm apply except there is a pause in the rhythm

Atrial fibrillation

Atria are not in sync, some pathologic process has caused the multiple irritable foci within the atria to send impulse signals.

Impulse initiation: unable to determine P waves or may have multiple p waves in between QRS complexes

Rate: rapid ventricular response (RVR) greater than 100, rate controlled less than 100

Rhythm: irregular

P waves: unable to determine

PR interval: unable to determine

QRS: less than 0.14 sec

P/QRS Ratio: unable to determine

Atrial flutter

Atria are sending off multiple impulses from one focal point. Some pathologic process has caused the impulses from the SA node to not reach the AV node initially

Impulse initiation: multiple P waves mimicking a saw tooth appearance

Rate: could be normal or rapid, depends on how many impulses are blocked before reaching the AV node

Rhythm: multiple P waves before each QRS, but is consistent

P waves: multiple

PR interval: unable to measure

QRS: less than 0.14 sec

P/QRS Ratio: multiple P waves for each QRS. 2:1. 3:1…

Premature atrial contraction (PAC)

Atria decides to depolarize too early, stepping on the ST segment of the preceding wave

Impulse initiation: initiated from the SA node

Rate: normal

Rhythm: normal except for _

P waves: normal except for _

PR interval: normal for _

QRS: less than 0.14 sec

P/QRS Ratio: 1:1

Supraventricular tachycardia (SVT)

Impulse initiation: coming from somewhere within the atria or AV junction. Umbrella term for any non-ventricular tachycardia over 150 BPM

Rate: greater than 150 BPM

Rhythm: QRS complexes march out, just really fast

P waves: unable to determine unless slowed down

PR interval: unable to measure unless slowed

QRS: 0.14 sec or less

P/QRS Ratio: generally, looks as though it is 1:1, but often too fast to tell

Atrial fibrillation

Rate can vary depending on ventricular (QRS) response, unable to determine p waves or PR interval, distance between R to R is inconsistent, multiple or unable to determine p waves

Atrial flutter

Rate can vary depending on ventricular response, R to R distance is consistent and will have multiple p waves resembling saw tooth appearance

Atrial tachycardia

Very rapid rate generally greater than 150, but most common over 180. Can also be classified under the SVT umbrella

Premature atrial contraction

Atrial conduction comes early stepping on the preceding ST segment. Will look like a regular complex that comes early. All measurements are within the normal range

SVT

any NON-ventricular tachycardia over 150 BPM that is too fast to interpret otherwise (umbrella term)

Junctional

Impulse initiation: Impulse is originating from within the AV junction. SA node may be diseased or being blocked by a diseased muscle tissue, or the SA node is firing at a rate lower than the AV node

Rate: Intrinsic rate of the junction is 40-60

Rhythm: rhythm looks regular with inverted, varying or absent p waves

P waves: unable to determine if p wave is absent

PR interval: unable to measure if p wave is absent

QRS: less than 0.14 sec

P/QRS Ratio: 1:1 if present, unable to determine if absent

Accelerated junctional

Impulse initiation: impulse is originating from within the AV junction. SA node may be diseased or being blocked by diseased muscle tissue, or the SA node is firing at a rate lower than the AV node.

Rate: 60-100

Rhythm: rhythm looks regular with inverted, varying or absent p waves

P waves: unable to determine if p wave is absent

PR interval: unable to measure if p wave is absent

QRS: less than 0.14 sec

P/QRS Ratio: 1:1 if present, unable to determine if absent

Junctional tachycardia

Impulse initiation: Impulse is originating from within the AV junction. SA node may be diseased or being blocked by diseased muscle tissue, or the SA node is firing at a rate lower than the AV node.

Rate: Greater than 100; if over 150 and unable to determine, SVT umbrella

Rhythm: rhythm looks regular with inverted, varying or absent P waves

P waves: unable to determine if p wave is absent

PR interval: unable to measure if p wave is absent

QRS: less than 0.14 sec

P/QRS Ratio: 1:1 if present, unable to determine if absent

Premature junctional contraction (PJC)

AV junction decides to depolarize too early stepping on the PR interval of the wave.

Impulse initiation: initiated from the AV node

Rate: normal

Rhythm: normal except for _

P waves: normal except for _

PR interval: normal except for _

QRS: less than 0.14 sec

P/QRS Ratio: 1:1 except for _

Junctional

slow rate of 40-60, p wave will be absent or inverted (because impulse is generated from the AV junction and sent up to the atria resulting in inversion), there is no PR interval if p waves are absent. QRS normal

Accelerated junctional

Rate of 60-100, p wave will be absent or inverted (because impulse is generated from the AV junction and sent up to the atria resulting in inversion), there is no PR interval if p waves are absent. QRS normal

Junctional tachycardia

Rate greater than 100 (if rate over 150, falls under SVT umbrella). P wave will be absent or inverted (because impulse is generated from the AV junction and sent up to the atria resulting in inversion), there is no PR interval if p waves are absent. QRS normal

Premature junctional contraction

underlying or intrinsic rhythm is generally normal, just have an early beat arising from the AV junction. Results in an early beat after the preceding ST segment with an inverted or absent p wave.

First degree AV block

Impulse initiation: Initiated from the SA node, but because of disease process or conduction defect, there is a delay in the conduction from SA to AV

Rate: regular or on the slower side of regular

Rhythm: regular

P waves: regular

PR interval: 0.20 or greater in length

P/QRS ratio: 1:1 ratio

QRS: less than 0.14 sec

Second degree AV block type 1, Mobitz 1, Wenckebach

Impulse initiation: Impulse is initiated from the SA node, but because of nodal disease the impulse is blocked and or slowed during conduction

Rate: regular or brady

Rhythm: irregular

P waves: more p waves

PR interval: longer, longer then it drops now you have a _

P/QRS ratio: More p’s than QRSs

QRS: less than 0.14 sec

Second degree AV block type 2, Mobitz 2

Impulse initiation: Initiated in the SA node, multiple impulses being blocked to the AV node

Rate: regular or brady

Rhythm: distance from p wave to p wave “marches out”

P waves: regular and consistent

PR interval: even though there are more p’s than QRS’s, the interval is consistent

P/QRS ratio: more p’s than QRS’s, but the PR interval is the same

QRS: less than 0.14 sec

Third degree AV block, complete heart block

Impulse initiation: SA node initiates the atrial activity and is blocked at the AV junction, forcing ventricular conduction to be initiated further down the pathway resulting in a slower rhythm (20-40 BPM)

Rate: slow 20-40

Rhythm: P wave to p wave distance is consistent and R to R is consistent

P waves: regular in shape and size

PR interval: unable to determine/variable

P/QRS ratio: more p’s than QRSs, but there is no correlation between the two

QRS: less than 0.14 sec

first degree heart block

PR interval is greater than 0.20, that’s it. Everything else will look normal or slow

Second degree type 1, Mobitz 1 or Wenckebach

More p’s than QRS’s and the PR interval gets longer, longer than it drops (the QRS complex) now you have a _

Second degree type 2, Mobitz 2

More p’s than QRS’s, but the PR interval is consistent and if measuring p to p to p to p the distance is always the same

Third degree or complete heart block

More p’s than QRS’s but there is no correlation between the two. There is no PR interval. P to P matches and R to R matches.

Intraventricular Conduction Delay

Impulse initiation: Initiation originates from the SA node but is delayed when conducting through the bundle branches and throughout the ventricles. Resulting from some sort of disease process and may or may not regain loss of function. May be called a Bundle Branch Block

Rate: could be too slow, too normal or too fast

Rhythm: could be normal

P waves: regular in size, shape and color

PR interval: consistent

P/QRS ratio: 1:1

QRS: 0.14 sec or greater, results from one side conducting and then moving up and down the other side for conduction of that ventricle

Premature ventricular contraction (PVC)

Impulse initiation: Depends on the underlying rhythm, but generally normal. Normal conduction except during the PVC. Normal conduction except during the PVC. An irritable focus causes the ventricle to contract early, resulting in an abnormal beat with a wide, bizarre QRS. Can be paired, unifocal or multi focal

Rate: Non rate specific

Rhythm: Normal except for event

P waves: Normal except for event

PR interval: Normal except for event

P/QRS ratio: Depends on the underlying rhythm

QRS: greater than 0.14 sec for each PVC

Ventricular Tachycardia

Impulse initiation: May or may not have atrial activity. Impulse is generating from the ventricles. May or may not have a pulse

Rate: Greater than 100 BPM

Rhythm: Regular/monomorphic (impulse generating from some focal point within ventricles). Irregular/polymorphic (impulse is generated from multiple areas within the ventricles)

P waves: unable to determine

PR interval: unable to measure

P/QRS ratio: unable to determine

QRS: greater than 0.14 sec

Ventricular Fibrillation

Impulse initiation: Erratic fibrillation of ventricles, no true impulse, no perfusion or pulse. Treatment varies on code status

Rate: Greater than 100 BPM

Rhythm: Coarse or fine, depends on amplitude of wave form (does not change course of treatment)

P waves: unable to determine

PR interval: unable to determine

P/QRS ratio: unable to determine

QRS: unable to determine

Pulseless Electrical Acticity

Impulse initiation: SA node

Rate: could be too slow or too fast

Rhythm: may look like a sinus rhythm on monitor

P waves: could be normal

PR interval: could be normal

P/QRS ratio: could be normal

QRS: could be nornal

There is NO pulse

Asystole

Impulse initiation: There is no impulse

Rate: There is not one

Rhythm: There is not one

P waves: May still see atrial impulses on the monitor, but no pulse, nor any ventricular activity

PR interval: None

P/QRS ratio: None

QRS: None

Intraventricular conduction delay (IVCD)/Bundle branch block

Everything else is normal, just the ventricular conduction is low resulting in a wider QRS 0.14 or greater

Premature ventricular contraction

Arises from the ventricles resulting in an early wide bizarre QRS with ST segment in the opposite direction

Ventricular tachycardia

Consistent wide QRS waveforms, can be unifocal (all look the same) or multifocal (look different)

Ventricular fibrillation

Just a quivering line with no obvious atrial or ventricular conduction

Pulseless electrical activity

Looks like a regular rhythm on the monitor, but the patient has no pulse

Asystole

flat line

Torsades de Pointes

Impulse initiation: ventricles

Rate: unable to determine

Rhythm: irregular

P waves: unable to determine

PR interval: unable to determine

P/QRS ratio: unable to determine

QRS: unable to determine

Idioventricular rhythm

Impulse initiation: ventricles

Rate: usually slow 20-40 beats/min

Rhythm: regular

P waves: none

PR interval: none

P/QRS ratio: unable to determine

QRS: wide

Wandering atrial pacemaker

Impulse initiation: multiple points in the atria

Rate: most often under 100 beats/min

Rhythm: irregular

P waves: at least three different morphologies

PR interval: may vary slightly

P/QRS ratio: usually narrow

QRS: usually 1:1

Torsades de Pointes

irregular rhythm, impulse initiated from ventricles, unable to determine everything else, similar to v-tach but larger, looks like audio waves

Idioventricular rhythm

slow rate (20-40), wide QRS with a t-wave in the opposite direction, no p waves

Wandering atrial pacemaker (WAP)

impulse is initiated at multiple points in the atria, rate is usually <100, irregular rhythm, at least 3 different p wave morphologies, PRI may vary slightly, QRS usually narrow

Atrial paced rhythm (A-paced)

Pacer spike followed by a p wave then QRS, may occur every beat or only as needed depending on pacemaker settings

Ventricular paced rhythm (V-paced)

Pacer spike followed by a wide QRS (generally deflected in the opposite direction). May or may not have their own preceding p wave. May occur with each beat or as needed, depending on settings

Dual paced rhythm (AV-paced)

Pacer spike followed by a p wave then another pacer spike followed by a QRS complex. May occur with each beat or only as needed