Ventricular Rhythms

What are they?

There are ectopies and escape rhythms. Ectopies arise from an irritable focus in the ventricles. They can be single beats, groups or rums of beats, or entire rhythms. If the ectopic rhythm is faster than the current pacemaker, it will take over the pacemaking of the heart. Ventricular escape rhythms occur when all the pacemaking sites above the ventricles fail and the ventricular pacemaker takes over.

Premature Ventricular Contractions (PVC’s)

Example of PVC

This is not a rhythm. It is an ectopic beat originating from an irritable ventricular focus. PVC’s usually have the T wave deflecting in the opposite direction of the QRS complex (unlike a normal QRS, T wave). They usually follow by a compensatory pause. This is due to the fact that the SA node did not fire when the PVC did so it waits until the next time it is supposed to fire.

· Rules:

Regularity and rate usually depend on underlying rhythm.

NOTE: PVC’s are usually not counted in the rate determination. However, it may depend on who you ask. The rule is actually to only count the PVC in the rate if it is perfusing, meaning you can feel a pulse with it. Therefore, the best bet is to find, if possible, a 6-second strip of the patient's underlying rhythm without any PVC's to determine the actual heart rate.

Not associated with any P wave, therefore also no PRI

QRS is wide and bizarre: >0.12sec. Will be a different configuration from the other normal QRS complexes in the underlying rhythm.

· Causes: Sometimes there is no apparent cause. Sometimes caused by hypoxia, stress, stimulants, acid-base imbalance, electrolyte imbalance, MI, or CHF.

· Clinical Picture: Can be asymptomatic or may c/o palpitations, racing/fluttering heart, or CP.

· Management: O2, monitor. May use Beta blockers or antiarrhythmics like Lidocaine.

· Interpolated beats

Example of Interpolated PVC’s

Not all PVCs are followed by a pause. If a PVC occurs early enough (especially if the heart rate is slow), it may appear sandwiched in between two normal beats. This is called an interpolated PVC.

· Unifocal vs Multifocal

Example of Unifocal PVC’s

Unifocal: This means the PVC’s are coming from a single irritable focus in the ventricle. They will be similar in appearance.

Example of Multifocal PVC’s

Multifocal: This means the PVC’s originate from different irritable foci in the ventricle. The PVC’s will look differently and possibly deflect in different directions. Multifocal is more serious because it indicates a more irritable ventricle.

· R on T Phenomenon

Example of R on T Phenomenon

This occurs when the R wave of a PVC falls on or near the relative refractory period of the cardiac cycle (the end of the T wave). This is concerning because it can cause the heart to go into a life threatening arrhythmia (as shown in picture above).

· Couplets and Runs

Example of PVC couplet (unifocal)

Examples of PVC couplet (multifocal)

Sometimes PVC’s occur in immediate succession without a normal beat in between. Two in a row are called a couplet. Three or more in a row are called runs. Can represent a very irritable heart and can be serious.

Example of run of PVC’s

· Grouped Beats

This occurs when the PVC’s fall into a pattern with the surrounding normal beats.

Example of bigeminy

Bigeminy: Every other beat is a PVC. PVC, one normal beat, PVC, one normal beat, etc.

Example of trigeminy

Trigeminy: Every third beat is a PVC. PVC, two normal beats, PVC, two normal beats, etc.

Example of quadrigeminy

Quadrigeminy: Every fourth beat is a PVC. PVC, three normal beats, PVC, three normal beats, etc.

Ventricular Tachycardia

Example of V-tach

This is a rhythm that originates from an irritable ventricle. Because it is a fast rhythm, it takes over as the pacemaker of the heart. This rhythm can be deadly. Patient may start out ok, but will quickly become unstable and possibly lose their pulse.

· Rules:

Regular or slightly irregular

Rate: Ventricular rate is 150-250bpm. If rate <150bpm, it’s called “Slow VTach”. P waves: None of the QRS’s will have preceding P waves PRI: None QRS: Wide and bizarre, >0.12sec

· Causes: CAD, prior MI, cardiomyopathy, trauma, invasive cardiac procedures, acid-base imbalance, electrolyte imbalance (low Mg, low K, high K), cocaine

· Clinical Picture: Patient will begin to lose consciousness as perfusion decreases. Can quickly become pulseless if they have not already. Can also quickly turn to ventricular fibrillation.

Management:

*Pulse and stable: Lidocaine or Amiodarone

*Pulse and unstable: Use the above meds and cardioversion

*No pulse: CODE BLUE. Start CPR, ACLS. Defibrillate ASAP and continue with ACLS meds.

· Torsades de Pointes

Example of Torsades de Pointes

Means “twisting of the points”. This is a polymorphic form of V-tach.

Cause: Associated w/ prolonged QT intervals, R on T phenomenon, low Mg, low K. Commonly seen in malnourished individuals and chronic alcoholics. Medication effects that can cause prolonged QT interval such as amiodarone, methadone, lithium, chloroquine, erythromycin, phenothiazines, sotalol, procainamide, quinidine, amitriptyline, fluoxetine, haloperidol, levofloxacin, and sertraline.

Clinical Picture: Patient will have symptoms of low cardiac output. It is hemodynamically unstable and causes a sudden drop in BP, leading to dizziness and syncope. Depending on their cause, many patients revert to normal sinus rhythm within a few seconds, but the rhythm may also persist and possibly deteriorate into ventricular fibrillation.

Example of Torsades de Pointes brought on by R on T Phenomenon

Management: Treat the cause. O2, monitor, get IV access.

IV Magnesium Sulfate. Can quickly deteriorate to ventricular fibrillation.

Ventricular Fibrillation

Example of Ventricular Fibrillation

This is uncoordinated contraction of the ventricles due to multiple irritable foci, making them quiver rather than contract properly and unable to perfuse blood throughout the body. A patient with this rhythm needs immediate ACLS attention. If continues for more than a few seconds will turn into asystole.

· Rules:

Regularity not able to be determined- baseline chaotic.

Rate: indeterminable

P waves: not discernible

PRI: none

QRS: none discernible

· Causes: Increased sympathetic nervous system activity, electrolyte and/or acid-base abnormalities (may need NaHCO3), medication effects, electrocution, trauma, MI.

· Clinical Picture: Clinically dead. Unresponsive, apneic, and pulseless.

· Management: CODE BLUE!! Start CPR, ACLS, and defibrillate ASAP. Use ACLS meds like Lidocaine, Amiodarone.

Idioventricular (Ventricular Escape)

Example of Idioventricular Rhythm

Ventricular escape can be single beats that kick in when the SA or AV nodes fail to fire when they are supposed to, then the SA or AV node kicks back in after the ventricular beat. If it does not kick back in, the patient will proceed to an idioventricular rhythm.

· Rules:

Usually regular

Usually 20-40bpm, but can drop below 20bpm.

No P waves

No PRI

QRS wide >0.12sec.

· Causes: MI, Digoxin toxicity, or other medication effects

· Clinical Picture: Due to the slow rate, patient is usually hypotensive with symptoms of low cardiac output. Can progress to agonal rhythm, then asystole.

· Management: Oxygen, monitor, IV. Atropine, transcutaneous pacing.

· Idioventricular vs Agonal:

Example of Agonal Rhythm

Agonal rhythm usually follows idioventricular and represents a dying heart. Usually slower than 20bpm.

· Accelerated Idioventricular

Example of Accelerated Idioventricular Rhythm

Usually considered a benign escape rhythm causing little or no hemodynamic instability. Appears when the SA and AV slow too much and disappears when they speed up. Seen commonly after MI’s and with Digoxin toxicity.

Asystole

Example of Asystole

No electrical activity. Just a straight line. However- always check two leads and your patient before determining asystole is indeed occurring. This is because an isoelectric line due to dislodged electrodes can sometimes mimic the appearance of asystole and vice versa. If it is truly asystole: CODE BLUE! Start ACLS immediately with meds like Atropine, Epinephrine, and may try transcutaneous pacing.

STOP! TIME FOR PRACTICE STRIPS ON VENTRICULAR RHYTHMS!

depolarized at about the same time. When the impulse travels backward todepolarize the atria, it is called “retrograde” conduction. This backwards impulse causes the P wave to look different, if it can be seen at all, on the EKG.

a. P waves in Junctional Rhythms

Inverted P waves:

In Lead II, remember, the “camera” is at the apex of the heart. If the impulse starts at the AV junction and has to travel in both directions, the P wave will be a negative deflection because the current is flowing away from the “camera”. The QRS will be positive as usual.

. Hidden P waves:

Because the depolarization of the atria occurs at the same time as the ventricles, the P wave may not be seen at all because it is hidden by the QRS.

· Late P waves:

The impulse may also reach and depolarize the ventricles before the atria. In this instance, the P wave comes after the QRS.

b. Premature Junctional Contractions (PJC’s)

Example of PJC

These are single ectopic beats in a rhythm. Occurs when an irritable focus in the junction stimulates a depolarization and interrupts the underlying rhythm for a single beat. Appears similar to PAC except the P wave will look different (see P waves section above).

· Rules:

Basically irregular due to interruption

Rate will depend upon underlying rhythm

P wave: will appear inverted, and come before, during, or after QRS

PRI: If P wave precedes QRS, will be usually less than 0.12sec

QRS: <0.12sec

· Causes: Nicotine, hypoxia, dig toxicity, caffeine, MI, stress, alcohol, infections, heart failure, mental or physical fatigue, hypomagnesemia, hypokalemia, or can occur in healthy hearts

· Clinical Picture: May feel palpitations or skipped beats

· Management: Usually none needed

c. Junctional Escape

Example of Junctional Escape Rhythm

When higher pacemaker sites fail, the AV junction is left with pacemaking responsibility.

· Rules:

Regular

Rate 40-60bpm

P wave: Inverted and can come before, during, or after QRS

PRI: If P wave precedes QRS, will be

QRS: <0.12sec

· Cause: Severe sinus bradycardia, vasovagal stimulation, hyperkalemia, drug effects like Beta-blockers, Ca channel blockers, Dig toxicity

· Clinical Picture: Slow pulse, may have symptoms of decreased cardiac output like, dizziness, fatigue, short of breath, syncope, but may be asymptomatic.

· Management: O2, monitor IV. Treat the cause. If symptomatic, drug therapy like atropine or pacemaker may be needed.

d. Accelerated Junctional Rhythm

Example of Accelerated Junctional Rhythm

Occurs when an irritable site at the AV junction sends impulses at a faster rate than the SA node or other atrial pacemaker sites and takes over pacemaker responsibility of the heart.

· Rules:

Regular

Rate 60-100bpm

P waves are inverted and can come before, during, or after the QRS

PRI: If P wave precedes the QRS, it will be

QRS: <0.12sec

· Causes: MI, open heart surgery, myocarditis, Digoxin toxicity

· Clinical Picture: Usually asymptomatic

· Management: O2, monitor, IV. Treat cause.

e. Junctional Tachyicardia

Example of Junctional Tachycardia

· Rules: Regular

Rate 100-180bpm (NOTE: most of the time,

when >150, it may be hard to tell if rhythm is sinus, atrial, or junctional in origin, so new call it SVT).

P wave: Inverted and can come before, during, or after QRS

PRI: If P wave precedes QRS will be

QRS: <0.12sec

· Causes: MI, open heart surgery, myocarditis, Digoxin toxicity

· Clinical Picture: Fast pulse, may shows signs of decreased cardiac output, palpitations.

· Management: O2, monitor, IV. Vasovagal maneuvers, carotid massage, drug therapy such as Adenosine, Ca channel blockers, Beta-blockers, antiarrythmics, or cardioversion

2. Supraventricular Tachycardias (SVT)

a. What are they?

Example of SVT

A category of several regular tachyarrhythmias that can’t be identified further due to indistinguishable P waves, rate 150-250bpm. Is usually one of four rhythms:sinus tach, atrial tach, atrial flutter, or junctional tach.

b. P waves in SVT

Not discernible due to the fast rate of the rhythm.

Atrial Rhythms

Cardiac conduction system

Wandering atrial pacemaker

Example Wandering atrial pacemaker

· Rules: R-R slightly irregular ,

Rate 60-100bpm ,

P wave appearance changes with each beat ,

PRI varies but is usually

· Causes: Can be normal- seen in very young, very old, or athletic patients

· Clinical Picture: Usually asymptomatic

· Management: None needed

Premature Atrial Contractions (PAC’s)

It is a type of atrial ectopy caused by irritability. It is a single beat. It is important that you always identify the underlying rhythm and locate the ectopies throughout that rhythm.

Example of PAC

· Rules: Rhythm will appear irregular due to the ectopic beats interrupting.

Rate depends on underlying rhythm

P wave of the PAC will look different from the rest of the strip. It usually has a QRS following but can be blocked.

PRI 0.12-0.20sec (PAC’s PRI may be longer or different from the others)

QRS <0.12sec

· Causes: fatigue, hypoxia, Digoxin toxicity, caffeine, ischemia, CHF, or ETOH

· Clinical Picture: irregular pulse, but usually asymptomatic

· Management: Treat the cause. Monitor as it can lead to atrial tachyarrythmias. Oxygen, monitor, IV.

Atrial Tachycardia (AT)

Because of its fast rate and supraventricular origin, atrial tachycardia usually gets interpreted as SVT (See SVT in next section)

· Rules:

Regular

150-250bpm

P wave is atrial in origin (not sinus) and may be lost or hidden in T wave due to the fast rate

PRI 0.12-0.20sec

QRS <0.12sec

· Causes: Excessive amount of catecholamines like epinephrine, norepinephrine, and dopamine, or Digoxin toxicity

· Clinical Picture: Rapid, regular pulse. May show symptoms of decreased cardiac output like, dizziness, fatigue, short of breath, syncope. May have chest pain or palpitations

· Management: O2, monitor, IV. Vasovagal maneuvers, carotid massage, drug therapy like Ca channel blockers, Beta-blockers, antiarrhythmics, or cardioversion.

Atrial Flutter (A-Flutter)

Example of Atrial flutter

· Rules: Usually regular but can be irregular

Atrial rate is usually 250-350bpm, ventricular rate can vary

P waves are upright and sawtooth

PRI –not applicable

QRS <0.12sec

· Causes: CAD,Rheumatic heart disease, hyperthyroid, MI

· Clinical Picture: If there is a rapid ventricular response- patient may have symptoms of decreased cardiac output like, dizziness, fatigue, short of breath, syncope and palpitations. Can lead to CHF.

· Management: Oxygen, monitor, IV. Treat the cause. Anticoagulant therapy is initiated due to increased risk of clots (the rapid atrial contraction causes turbulence in the blood which the body thinks is an injury- this causes platelets to collect at the site of the turbulence causing clots). If there is RVR, drug therapy such as Ca channel blockers, beta-blockers, and antiarrhythmics like Digoxin, Corvert, or Amiodarone can be used. Atrial pacing and cardioversion are options if patient becomes unstable.

Atrial Fibrillation (A-Fib)

Example of A-Fib

· Rules: Totally irregular.

If ventricular rate 100 “Rapid ventricular response”

No true P waves are produced in this rhythm, just fibrillatory waves

PRI unmeasurable

QRS <0.12sec

· Causes: MI, Digoxin toxicity

· Clinical Picture: Irregular pulse, may have symptoms of decreased cardiac output like, dizziness, fatigue, short of breath, syncope and palpitations. Can lead to CHF.

· Management: Oxygen, monitor, IV. Treat the cause. Anticoagulant therapy is initiated due to increased risk of clots (the rapid atrial contraction causes turbulence in the blood which the body thinks is an injury- this causes platelets to collect at the site of the turbulence causing clots). If there is RVR, drug therapy such as Ca channel blockers, beta-blockers, and antiarrhythmics like Digoxin, Corvert, or Amiodarone can be used. Atrial pacing and cardioversion are options if patient becomes unstable.

STOP! TIME FOR PRACTICE STRIPS ON VARIOUS ATRIAL RHYTHMS

Sinus Rhythms

Normal Sinus Rhythm

Examples of NSR

· Rules: 

Regular

60-100bpm

P wave is uniform, upright ,and there is one in front of every QRS

PRI is 0.12-0.20 and constant

QRS <0.12

· Causes: Normal

· Clinical Picture: Asymptomatic

· Management: None needed

Sinus Bradycardia
Example of Sinus bradycardia

· Rules: Regular

<60bpm

P wave uniform, upright, and one before every QRS

PRI 0.12-0.20sec and constant

QRS <0.12sec

· Causes: Sleep, hypothyroid, drug effects like beta-blockers, Ca+ channel blockers, and antiarrythmics, MI, increased ICP, increased vagal tone (i.e.athletes).

· Clinical Picture: Often asymptomatic, but may show symptoms of decreased cardiac output like, dizziness, fatigue, short of breath, syncope

· Management: If symptomatic, may give drugs to increase HR, apply pacemaker, etc. Also use O2, monitor, IV.

Sinus Tachycardia

Example of Sinus tachycardia

· Rules: Regular ,

<100bpm ,

P wave same as above ,

PRI 0.12-0.20sec, constant ,

QRS <0.12sec

· Causes: Stress, anxiety, dehydration, pulmonary embolus, fever, exercise, anemia, drug effects (caffeine, cocaine, nicotine), shock, MI, hyperthyroid

· Clinical Picture: Often asymptomatic, but depends on cause. May have palpitations, SOB, chest pain

· Management: Usually should try to treat the cause. Also Use O2, monitor, IV.

Sinus Arrythmia

Example of Sinus Arrhythmia

Also called “Respiratory Sinus Arrhythmia”. Occurs when your heart rate cycles with your breathing. When you breathe in, your heart rate speeds up slightly. When you breathe out, your heart rate slows back down.

· Rules: R-R intervals vary; change with patient’s respirations ,

Rate usually 60-100bpm, but can be slower ,

P wave same as above , PRI 0.12-0.20sec, constant ,

QRS <0.12sec

· Causes: Usually a normal phenomenon. Common in children, young adults, and athletes.

· Clinical Picture: Irregular pulse but usually asymptomatic

· Management: Usually none needed

Sinus pauses and sinus arrest

Caused when the sinus node fails to generate an electrical impulse to stimulate the heart to beat. Many times both of these categories are lumped into one called “Pauses” when interpreting rhythms.

1) Sinus Pause/Sinus block

A sinus pause is followed by a delayed, next sinus beat only.

Example of Sinus pause/Sinus block

· Rules: Irregular due to pause. Pause must be followed by a sinus beat.

Length of the pause is usually the same as or a multiple of the distance between two other P-P intervals.

Rate is usually normal but depends on the underlying rhythm.

P waves are uniform, upright, and before every QRS.

PRI 0.12-0.20sec, constant

QRS <0.12sec

· Causes: acute MI, medication effects like Digitalis, and other antiarrhythmics, CAD, myocarditis, CHF, increased vagal tone

· Clinical Picture: May show symptoms of decreased cardiac output like, dizziness, fatigue, short of breath, syncope

· Management: Usually treat the cause. Use O2, monitor, IV.

2) Sinus Arrest

A pause, however, many times is followed by an escape beat. This is called sinus arrest as the sinus node is taking too long to beat again needs help from the AV node.

NOTE: Patients with sinus arrest may have a history of syncope, near syncope, and/or falls.

· Rules: Irregular due to pause.

Pauses will vary in length and are usually more than one PQRST complex long.

Rate varies depending on underlying rhythm.

P waves uniform, upright, and one before every QRS

PRI 0.12-0.20sec, constant

QRS <0.12sec

· Causes: hypoxia, MI, high potassium, Digoxin toxicity, medication effects like Beta-blockers and Ca+ channel blockers

· Clinical Picture: May show symptoms of decreased cardiac output like, dizziness, fatigue, short of breath, syncope

· Management: Usually treat the cause. Use O2, monitor, IV.

STOP! TIME FOR PRACTICE STRIPS ON VARIOUS SINUS RHYTHMS