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3) Study the clinical course and do the practice strips at the end of each section.

4) Complete the post-test and submit. We will score your test.  You must score 80% or higher to pass.Re-take as much as you need to. We will coach you!

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How does the course work? Check out our intro video here:

Pacemakers

Pacemakers can be temporary or permanent. Temporary are used in emergencies and usually used only a few days at most. They inserted transvenously (inserted through a vein) or applied transcutaneously (on the skin).

a. Types of Pacing Response

Example EKG strip with Triggered pacing

1) Triggered- Fixed rate. Fires according to a predetermined program regardless of patient’s underlying heart rate or rhythm. (i.e. pacer is programmed to send 75 impulses to the ventricles every minute regardless of what the atria are doing as in the strip below).

Example EKG strip with Inhibited pacing

2) Inhibited- Fires only when needed. Senses patient’s own rhythm and inhibits its impulse until needed (i.e. the ventricle or atria stop beating or are beating too slow, etc). In the strip below, you can see the pacer only kicks in after the patient's ventricles fail to beat.

Can be both: Triggered atrial, (this means the pacer sends an impulse to the atria regardless of how the atria are beating) and inhibited ventricular (this means it senses ventricular beats and fires only when ventricles need it to).

b. Common Kinds of Inhibited Pacers

1) Single chamber- Senses and stimulates either atria or ventricles but not both

2) Dual chamber-Works on both chambers simultaneously. Most common is DDD-Dual pacing for both chambers, Dual chamber activity sensing, and Dual response (triggering and inhibition).

c. Assessment
Always check your patient to assure the mechanical and electrical are both working.

1) Things to assess
· Does each pacer spike capture and get followed by either a P wave or QRS (depending on the type of pacer)?

(In the picture below, there are way more pacer spikes than QRS's, not every pacer spike is followed by a QRS meaning that even though the pacer is firing as programmed, the heart is not responding appropriately.)

· Is the rate reasonable? (Usually 60-100)

· Are the pacer spikes competing with the patient’s underlying rhythm or falling near T waves? (Spikes falling near T waves can throw a patient into Vtach or Torsades)

· Is pacer firing consistently and reliably?

d. Common Malfunctions

1) Failure to Capture- pacer firing, creating pacer spikes, but heart does not respond (no P wave or QRS after)

2) Failure to Pace- Pacer fails to deliver correct number of stimuli or sometimes any stimulus at all.

3) Competing with patient’s own intrinsic rhythm- can be for two reason and either of these can be bad if the depolarized beat falls near the T wave of the previous beat

STOP! TIME FOR PRACTICE STRIPS ON ALL RHYTHMS!

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.