basic dysrhythmias

Basic Dysrhythmias

Chemeketa Paramedic Program-Basic Anatomy of the Heart

-Electrical Conduction of the Heart

-A System of Defining 3-Lead EKG’s

What is an:

EKG? ECG? EEG? EGG?

Isn’t School Great?

Heart A & P

Location Pieces, Parts Important Vessels Electrolyte Role Pulling apart

waveforms

Review of Important Vessels

CONDUCTION SYSTEM

A System of Checks & Balances

Baroreceptors (Pressoreceptors)– Found:

Internal carotid arteries Aortic Arch

Chemoreceptors– Found in same places

– Monitors pH, O2 & CO2

Respond by:– Stimulating sympathetic

Adrenergic response Alpha, Beta & Dopaminergic Norepi & Epi release

– Inhibiting Parasympathetic Acetylcholine

– Cholinergic Response

– Medulla Regulatory organ

Electrical Conduction System Sympathetic-Thoracic/Lumbar Nerve

– Norepinephrine HR, Contractility

Parasympathetic-Vagus Nerve– Acetylcholine

HR (Valsalva)

Chronotropic-HR

Inotropic-Contraction

Electrolytes & Conduction

“Excitable” cells of the Heart

Self-depolarizing cells (Automaticity)

Electrolytes of the Heart (Na+ / K+/ Ca++)

Electrolytes & Conduction

Membrane Potential (MP)– Slight difference between charge inside & out

Threshold– MP becomes high enough to depolarize

Action Potential– Ability of cells at a given time– Difference (mV) between inside & out

The Cardiac Cycle

Membrane Potential

Sodium-Potassium MP Rises

– Na+ Channels Open– Rapid Influx (Fast Channels)

Cell Attains + Charge– K+ Channels Open– Outflow

The Pump– ATP Transports:– 3 Na+ out & 2 K+ in– Restores Resting cellular

conditions

Calcium– Slow Channels– Selective Permeability

“The Wave”– One cell contraction

Spreads

Electrical Conduction System

Na+ - Depolarization K+ - Repolarization

– > = < Automaticity & Conduction– < = > Irritability

Ca++ - Depolarization and Contraction– > = > Contractility– < = < Contractility, > Irritability

Electrical Conduction System

Na+ in & K+ out = Depolarization K+ in & Na+ out = Repolarization

– Imbalances in K+ or Na+

Effects Automaticity & Conduction Hypo & hyperkalemia affects irritability

Ca++ - Depolarization and Contraction– Affects Contractility– Hypo & Hypercalcemia effects contractile force

I know what you’re thinking…Who gives a @#$% !!! You are caring for a patient with a rapid heart rate. You

follow protocols and administer 20mg of Diltiazem.– You’re patient responds by becoming:

Less responsive Bradycardic B/P drops to 72/40 Weak Pulse at wrist Not responding to fluid, time or positioning.

What now??? Calcium Gluconate 10%

– 500 – 1000 mg slow IV Push

@#$% = Dang

Phases

Phase 0 – Rapid Depolarization– Reached max potential -90mV– Fast Na+ Channels Open– Cell now positive +25mV

Phase 1 – Early Rapid Repolarization– Fast Na+ Channels Close– K+ still being lost– MP approaching 0mV

Phase 2 – Prolonged Slow Repolarization– Plateau Phase– Muscle finishing contraction– Beginning to relax– MP staying close to 0mV

Phases

Phase 3 – End of Rapid Repolarization– K+ returns to inside– Cell returns to -90mV– Almost ready

Phase 4– Na+ - K+ Pump turns on

Sends Na+ out Brings K+ in

Ready to do it all over again now

Refractory PeriodsExcuse me!!! I hate to interrupt again, but, who cares???

Absolute Refractory Period– Polarity of cell prohibits depolarization

Relative Refractory Period– Cell is returning to ready state for

depolarization– Impulse now is BAD!!!

R on T Phenomenon– Causes VT & VF– Treated with defibrillation

Can be caused by:– Frequent FLB’s– EMT-P not pushing the “sync”

button

The Electrocardiograph (ECG, EKG)

Electrical Activity– Not Heart Action

Records + and – impulses Paper runs at 25mm/s Counting Rates

– 300-150-100-75-60-50– 6 second strip x 10– 10 Second Strip x 6– The little number on the monitor

Lead Considerations

$25,000 mVoltmeter– Lead Views:

1 – Lateral 2 – Inferior 3 – Inferior

The Components

SA Node Internodal Pathways AV Junction AV Node Bundle of His L & R Bundle Branch Purkinje Network Purkinje Fibers

Ode to a Node

Have a heart, and have no fear,The SA node is over here.Beating at a constant rate,60 – 100 is really great.

The AV node can make a show,If SA node has gone too slow.

40 – 60 is not too badIf it’s all you’ve got, you will be glad.Should the whole thing drop it’s speed,

His and bundle branches will take the lead.And that, my friend is the whole and part,Of the conduction system of your heart.

– Flip and See ECG, Cohn/Gilroy-Doohan

Sino Atrial Node

The Natural “Pacemaker”– Connects directly

to atrial fibers

Fires 60-100 times per minute Wavelike Atrial Depolarization The P-Wave P-Wave

P-R Interval

Q-Wave

.04 Sec .04 Sec .04 Sec .04 Sec .04 Sec

0.20 Seconds per 5 Boxes

AV Junction

Receives impulses from SA Node via the Atrial Cells– An electrical funnel– Impulses hit at various times– Causes delay

PR-I

– Susceptible to blockage Path from A to V

– Delivers impulse to the AV Node

Atrio-Ventricular Node

Lies between the Atria and Ventricles

Collects impulses from above

Stimulates Ventricles If unstimulated

– Intrinsic rate 40-60

Bundle of His / Left and Right Bundle Branches

Distributes Impulses from the Node “The Ventricular Messengers”

Purkinje Network/Fibers

Direct connection with ventricular tissue

Intrinsic rate 20-40 if unstimulated

P-Wave

P-R Interval

QRS Complex

T-Wave

P-Wave

P-R Interval

QRS Complex

T-Wave

Q

R

S

PRI

Baseline

The Six Step Approach

What is the Rate? Is the Rhythm Regular? Are there P-Waves? Is the P-R Interval Normal? Is the QRS Complex Normal? Is There a P-Wave for Every QRS?

Step 1 = Rate

Is the rate between 60-100 (Sinus) Between 40-60 (Junctional/Bradycardic) Above 100 (Tachycardic) Between 20-40 (Ventricular)

Step 2 = Regularity

At-a-glance: Does it look regular? Are the P-Waves evenly spaced? Are the QRS Complexes evenly spaced?

Step 3 = P-Waves

Are P-Waves present? Are they upright and rounded? Are they irregular in any way: Notched /

Peaked / Depressed…? Are they all the same?

Step 4 = P-R Interval

Is the P-R Interval between 0.12-0.20? Is it too long / too short? (Block) Is it the same on every conduction? Is it absent?

Step 5 = QRS Complex

Is it there? Is it between 0.04 - 0.12? Does it have any abnormalities? (Notched /

Rabbit Eared / Wide / Bizarre)

Step 6 = P-QRS Married?

Is there a P-wave for every QRS? Are there more P-Waves than QRS? Are the P-Waves after or within the QRS?

Describe What You’ve Found!!!

IN GENERAL (underlying rhythms)!!! What are the abnormalities? Does it originate in the Sinus Node? Does it follow through from the Atria to the

ventricles? Are there abnormal delays? What are the exceptions to the underlying

rhythm? (Describe those also)

EKG INTERPRETATION CHART

RHYTHM RATE REGULARITY P-WAVE (U/R) P-RINTERVAL

QRS P-QRSMARRIED

NSR 60-100 Regular Normal/Upright/Rounded

0.12-0.20 sec. 0.04-0.12

Yes

SinusTachycardia

Above100

Regular Normal/Upright/Rounded

0.12-0.20 sec 0.04-0.12

Yes

SinusBradycardia

Below 60 Regular Normal/Upright/Rounded

0.12-0.20 sec 0.04-0.12

Yes

SinusArrhythmia

60-100 Irregular Normal/Upright/Rounded

0.12-0.20 sec 0.04-0.12

Yes

AtrialFibrillation

UsuallyTachy

Irregular Not Discernible Not Discernible 0.04-0.12

NotDiscernible

Atrial Flutter May beNormal /Tachy

Atria-regular/Ventricles-regular or irregular

Sawtooth pattern,2:1, 3:1, 4:1 ratios

0.12-0.20 on theconducting beat

0.04-0.12

On theconductingflutter wave

(P)SVT 140-220 Regular In QRS/T complexor not present

Shortened orabsent

0.04-0.12

No

1st DegreeBlock

Normal Regular Normal/ Upright/Rounded

Longer than0.20

0.04-0.12

Yes

2nd Degree(Type 1)Wenckebach

Normalor Brady

Irregular Normal/Upright/Rounded

Lengtheninguntil beat isdropped

0.04-0.12

No

2nd Degree(Type 2)Mobitz II

Brady Irregular Normal/Upright/Rounded 2:1, 3:1, 4:1

Normal or longon conductedbeats

0.04-0.12

On theconducting P-Wave

3rd DegreeCompleteHeart Block

40-60 Atria-RegularVent.-Regular

Normal/Upright/Rounded

Atriaindependent ofVentricles

Usuallygreaterthan0.12

No

Junctional(accel/tach)

40-60(60+/100+)

Regular Inverted/Retrograde/Absent

Short/ Normal/Absent

0.04-0.12

Yes-if P-waveis visible

VentricularTachycardia

100-220 Usually Regular Not Discernible(usually)

Not Discernible Greaterthan0.12

No

VentricularFibrillation

Rapid/Chaotic

Irregular Not discernible NotDeterminable

Wide/Bizarre

No

Asystole 0 N/A None None None NoAgonalIdioventricular

20-40 Irregular None None Wide No

-PVC-Wide, Bizarre QRS Complex, Look at underlying rhythm. Can appear in couplets, triplets, or short runs of VT. Canbe multi-focal or uni-focal. Caused by random firing within the ventricles. No atrial firing.-PAC-Conducted beat appearing in an otherwise normal rhythm. Stimuli originates within the atria, but not in the SA.-If Bundle Branch Block occurs, QRS will usually be wider than 0.12.

Normal Sinus Rhythm Rate: 60 - 100 Regularity: Very P-Waves: Present and Normal P-R I: 0.12-0.20 sec QRS: 0.04-0.12 sec and Normal Married: 1 P: 1 QRS, no extras or shortages

Sinus Arrhythmia Rate: 60 - 100 Regularity: Irregular P-Waves: Present and Normal P-R I: 0.12-0.20 sec QRS: 0.04-0.12 sec and Normal Married: 1 P: 1 QRS, no extras or shortages

Sinus Tachycardia Rate: Over 100 Regularity: Regular P-Waves: Present and Normal P-R I: 0.12-0.20 sec QRS: 0.04-0.12 sec and Normal Married: 1 P: 1 QRS, no extras or shortages

Sinus Bradycardia Rate: Less than 60 Regularity: Regular P-Waves: Present and Normal P-R I: 0.12-0.20 sec QRS: 0.04-0.12 sec and Normal Married: 1 P: 1 QRS, no extras or shortages

Atrial Fibrillation Rate: Usually tachy Regularity: Irregular (Irregularly irregular) P-Waves: Not Discernible P-R I: Undeterminable QRS: 0.04-0.12 sec Married: Undeterminable

Atrial Flutter Rate: Usually tachy Regularity: Atria Regular

• Ventricles May be Irregular

P-Waves: Sawtooth Pattern 2:1, 3:1, 4:1... P-R I: 0.12-0.20 sec on conducting beat QRS: 0.04-0.12 sec Married: P-waves outnumber QRS

(Picket fence)

(Paroxysmal) Supra Ventricular Tach Rate: 140-220

Regularity: Regular P-Waves: Usually falls within the QRS-T

complex ( sometimes not visible) P-R I: Shorter than 0.12, or absent QRS: 0.04-0.12 sec and Normal Married: Undeterminable

SVT WPW

– Usually based on Hx.– Delta wave on Q– Shortened PR-I– No Verapamil – Accessory Path use increase

1st Degree Heart Block Rate: 60 - 100 Regularity: Very P-Waves: Present and Normal P-R I: Longer than 0.20 sec QRS: 0.04-0.12 sec and Normal Married: 1 P: 1 QRS, no extras or shortages

2nd Degree Heart Block (Type 1) Wenkebach

Rate: Can be Normal, or usually brady Regularity: Irregular P-Waves: Present and Normal P-R I: Lengthens until beat is dropped QRS: 0.04-0.12 sec and Normal Married: P-wave present on conducting beats,

increased delay causes missed QRS

2nd Degree Heart Block (Type 2)Mobitz II Rate: Less than 60

Regularity: Irregular P-Waves: Present, 2:1, 3:1, 4:1 P-R I: 0.12-0.20 sec on conducting beat QRS: 0.04-0.12 sec, may begin to widen Married: P-wave for every QRS and extras

depending on conduction ratio

3rd Degree Heart Block (CHB)Complete Heart Block

Rate: Ventricular Rate 40-60 Regularity: Atria-Regular

• Vent-Regular P-Waves: Present and Normal P-R I: Atria independent of Ventricles QRS: Usually greater than 0.12 sec Married: P-waves completely unrelated to QRS

Complexes.

Complete Heart Block

Junctional Rhythm Rate: 40-60 Regularity: Regular P-Waves: Inverted, Retrograde or Absent P-R I: Shortened or absent QRS: 0.04-0.12 sec Married: P-wave for every QRS, sometimes not

visible

Junctional

Junctional Accelerated Rhythm

Rate: 60-100 Regularity: Regular P-Waves: Inverted, Retrograde or Absent P-R I: Shortened or absent QRS: 0.04-0.12 sec Married: P-wave for every QRS,

sometimes not visible

Accelerated Junctional

Junctional Tachycardia

Rate: 100-140 Regularity: Regular P-Waves: Inverted, Retrograde or Absent P-R I: Shortened or absent QRS: 0.04-0.12 sec Married: P-wave for every QRS,

sometimes not visible

Junctional Tachycardia

Ventricular Tachycardia Rate: 100-220 Regularity: Regular P-Waves: None P-R I: None QRS: Greater than 0.12 sec Married: NO

We’ll look at Torsades de Pointes in Lab

Ventricular Tachycardia

Ventricular Fibrillation Rate: No ventricular rate Regularity: Irregular P-Waves: No P-R I: No QRS: No, unorganized ventricular baseline Married: No

Ventricular Fibrillation

Asystole

Rate: 0 Regularity: N/A P-Waves: None P-R I: N/A QRS: None Married: No (verify a second lead)

Asystole

Agonal / Idioventricular

Rate: 20-40 Regularity: Irregular P-Waves: None P-R I: N/A QRS: Wider than 0.12 sec Married: NO (a dying heart)

Idioventricular

Less regular than this!

Exceptions / Disruptions

Premature Ventricular Contractions Premature Atrial Contractions Bundle Branch Blocks Pacer Considerations (Atrial, Ventricular or

Both)

Premature Ventricular Contractions

Wide, Bizarre QRS Complex Always identify the underlying rhythm first Can appear in couplets, triplets, short runs of

V-Tach, bigeminy and trigeminy Can be uni-focal or multi-focal Caused by random firing within the ventricles Not accompanied by a P-wave

PVC’s

PAC’s P-QRS Complex

appearing in an unexpected location

Caused by a stimulus from within the Atria, but not from the SA Node

PJC

Bundle Branch Block

Any rhythm having a BBB will have a widened twin peaked R-Wave

Paced Rhythms

Patients may have various types of pacemakers

Atrial Ventricular Both Vertical spike on monitor is an indicator

Paced Rhythms Various

Artifact

60 Cycle Interference

Loose Leads/Moving Ambulance

In Summary

Really Cool Physiology!!! GENERAL RULES to Interpretation

– Applicable to 3 – lead monitoring Practice, Practice, Practice… Remember the rules, NOT how it looks

coming from one patient or one rhythm generator!!!

Sources – In order of preference

Many of the pictures and info from:– Flip and See ECG, 2nd Edition

Cohn/Gilroy-Doohan– A great resource

– Paramedic Paramedic Textbook, Revised 2nd Edition Mick J. Sanders, Mosby

– ECG’s Made Easy, 2nd Edition Barbara Aehlert, RN, Mosby

– Basic Dysrhythmias, Interpretation and Management, 3rd Edition

Robert J. Huszar, Mosby