EKG Rhythms- EXPH 3200

Atrial & Ventricular Depolarization

SA node initiates impulse

Impulse travels through Rt Atrium to Bachman's Bundle to Lt Atrium

Impulses reach AV node (delay occurs).

Rhythm rate

can be atrial or ventricular since they have different speeds

more P waves = increased atrial rate

more QRS = increased ventricular rate

Regular does NOT mean normal, instead it means...

it marches out appropriately

P:QRS ratio

1: 1

P waves

Should be consistent and look the same throughout an individual lead.

PR interval

should be consistent

0.12-0.20 seconds

beginning of P to beginning of QRS

What might a variable P wave suggest?

Heart is competing between SA and AV node

COULD be...AV node fires, but no P wave because it didn't listen to SA node

PR interval long- what might this be?

Block in AV node- AV holding for a while

P wave irregular rhythm- what might this be?

Losing the P wave

Firing early from atrium causing an extra beat

Retrograde P wave

P wave firing during ST segment

AV node releases signal into ventricles with a T wave

QRS complex

0.04-0.12 seconds

CAN look different from lead to lead

Appearance and duration SHOULD NOT change WITHIN a lead

If there is a change in the QRS within a lead, what might this mean?

change within ventricular contraction

Normal sinus rhythm

originates from SA node

A & V rate are equal (60-100 bpm)

Normal sinus rhythm- rhythym

regular

Normal sinus rhythm- P:QRS

1:1 ratio

Normal sinus rhythm- PR interval

0.12-0.20 seconds

Sinus bradycardia

HR < 60 bpm (a & v)

(all other criteria of normal sinus)

Sinus bradycardia- clinical significance

Can be normal in Athletes

May also be a sign of sinus node dysfunction in older person

Sinus bradycardia- how can we clinically assess this person?

Walk around and if HR goes up , means you are normal

Responds to activity

Sinus tachycardia

HR > 100 bpm (a & v)

(all other criteria of normal sinus)

Sinus tachycardia- clinical significance

exercise

pain

anxiety

drugs

heart abnormality

Sinus tachycardia- how can we assess it?

Lay down and see if HR goes down

Sinus arrhythmia- rate

Atrial and Ventricular rates usually between 60-100 bpm

Sinus arrhythmia- rhythm

Slightly irregular with areas that are faster and areas that are slower

Sinus arrhythmia- P waves, PR, QRS, P: QRS ratio

consistent, normal, 1:1

Sinus arrhythmia- clinical significance

Normal with respiration

Sign of healthy heart

Responds to changes within the body

So how would you measure HR in someone with sinus arrhythmia?

Take average of the two rates to get HR since one is fast and one slow

Sinus arrest/pause

Normal sinus rhythm with occasional "dropped beats"

Sinus arrest/pause- P, QRS, PR, P:QRS

entire PQRS is missing

period of asytole

How does sinus arrest different from sinus arrthymia

Sinus arrest- clinical significance

Vagal response

SA node dysfunction

Carotid massage

Meds

When should we NEVER see a sinus arrest?

Exercise

Should only see these at rest

How long does sinus arrest usually happen for? Do we feel it?

3-4 seconds

Don't feel it unless it is >4-5 seconds

Sinus arrest- how to assess if someone complains of passing out?

Heart monitor for 3-4 days to see if there's a pause for 3-4 seconds

Passing out happens from 4+ seconds which might not happen regularly but the 3-4 second one will

Sinus arrest- how to reat

long pause = use pacemaker to control rhythym

Supra-ventricular arrhythmia

originate in atria

P waves abnormal or absent

QRS normal and unchanged

Premature atrial contraction

early beat within atrium

Premature atrial contraction- characteristics (think P, QRS, etc.)

QRS unchanged

P wave absent/inverted/changed

Compensatory pause to reset system

PAC isolated- characteristics

Beat is early

P wave absent or changed

QRS normal

*Same as characteristics described earlier*

PAC bigeminy/couplets

Every other beat is premature

Rhythm could be defined as regularly irregular

QRS unchanged

Supra-ventricular Tachycardia (SVT)

Onset and termination are sudden and abrupt

Rhythm takes over atrium

SVT- rate

150-250 bpm

fast because sensitive to SNS and PNS?

SVT- rhythm

regular

super fast but marching out perfectly

SVT- P, P:QRS, QRS

P- buried in previous QRS

P:QRS = 1:1 if P is identifiable

QRS = unchanged

SVT- clincally

can happen in normal hearts

atrium is overworked

SVT- what does it look like on EKG strip? (Just generally)

Tachycardia very sudden then terminates and goes back to sinus rhythm

Atrial flutter

atrium fires repetitively at fast rate with some impulses blocked from ventricles

lots of P waves

not as many QRS

Atrial flutter- atrial rate

250-350 bpm

Atrial flutter- ventricular rate

varies based on block (3:1)

Cannot go faster than 300 bpm at fastest because of absolute refractory

Atrial flutter- rhythm

regular

Atrial flutter- P waves

sawtooth pattern

Atrial flutter- PR interval

not measurable

too many P waves

Atrial flutter- QRS

unchanged

Due to Av node sending signal down, so ventricles will respond normally

Atrial flutter- clincally

not in normal hearts

usually in cardiac issues (coronary artery disease, etc.)

atrial fibrillation

Quivering of electrical chaos running through the entire atrium

VERY VERY FAST

Afib- atrial rate

chaotic 350-600 bpm

looks like constant artifact

Afib- ventricular rate

varies, not organized

Afib- P:QRS

irregular

Afib- rhythm

very irregular

Constantly being hit with signals from all around

Afib- P waves

completely random

can't find regular P waves because atrium is quivering

Afib- clincally

usually right sided issues (COPD, PPH)

NOT in normal hearts

Junctional rhythms

everything stemming from AV node

Inherent rate = 40-60 bom

Abnormal/No P waves

PJC

No P waves

Early beat followed by pause

No change in QRS

PJC and PAC are the same

junctional escape beat

No P waves, then back to normal sinus

QRS normal

Junctional rhythm (accelerated or not)

No P wave

straight into QRS

QRS normal

Accelerated junctional rhythm is when HR = _________

>40-60 bpm (inherent rate of AV)

Ventricular arrhythmias

Rate of 20-40 bpm

QRS is WIDE (due to slow conduction thru ventricles)

PVC (premature ventricular contraction)

Normal QRS into WIDE QRS

Early beats from ventricles

PVC- causes

pretty common at rest

others....

-SNS stimulation

-caffeine

-hypoxia

-etc.

PVC bigeminy and trigeminy

Every other beat is PVC (three together for trigeminy)

Do all PVC's have the same morphology within a given lead? Why?

No- you can have one positive and one negative and still be PVC

Means these are coming from different parts of the heart

Ventricular escape rhythm

ventricles take over for AV and SA

20-40 bpm = inherent rate

NO P waves (so no PR interval, etc.)

QRS WIDE

Ventricular escape rhythm- causes

Sinus slowing or conduction failure

Associated with MI,

Very low rate it can be lethal!

Ventricular escape rhythm- actions

notify doc

treatment could be pacemaker

might need emergency measures

Accelerated ventricular rhythm

Ventricles at faster rate- 40-100 bpm

No P waves

WIDE QRS (>1.2)

Accelerated ventricular rhythm- causes/actions

seen in sick hearts

-MI

-SA slowing

-no treatment unless new finding

Ventricular tachycardia

3+ consecutive PVCs (aka...wide QRS)

Rate >100bpm

P wave not there

QRS is wide complex

NOTHING IS IDENTIFIABLE

Ventricular tachycardia- causes/actions

usually in SICK hearts but occasionally in normal hearts with genetic pre-disposition

Lethal because it reduces CO

Use BLS and ACLS (lifesaving measures)

Can someone with V-tach be talking to you?

yes, patient could be fine and talking, but is probably not comfortable

Ventricular fibrillation

Chaotic electrical impulses, sudden death occurrence

NOTHING CAN BE IDENTIFIED

NO QRS

Usually get smaller and smaller until you flatline

Can someone with V-fib be talking to you?

NO they will be UNCONSCIOUS

If they are conscious- it is NOT V-fib

V-Fib- causes/actions

lethal

dying hearts

no CO generated

BLS/ACLS immediately

Asystole

flat line, no electrical activity

will NOT be conscious, need to to use life-saving measures

Is there anything good about V-fib?

Yes- it's a shockable rhythm

if you get to it in time, there's a chance

Sometimes you can still see P waves on the strip in someone with asystole- why?

SA node might still be working a little bit or if someone is giving CPR you will see spikes from chest compressions

But it's STILL ASYSTOLE

AV conduction blocks

Inability of AV junction to conduct impulse to the ventricles in a NORMAL AMOUNT OF TIME

Relationship between P waves and QRS

1st degree AV block

PR interval LONG...>0.20 seconds

Everything else is normal...P:QRS, rates equal, rhythm normal

Wenkebach heart block

PR interval widens (gets longer) until a QRS is dropped and P wave is blocked

**husband comes home later and later each time, then doesn't come home, and then fixes the situation**

Wenckebach- ventricular rate, rhythm

Rate- slower than atrial rate, getting an extra P wave

Rhythm- varying

Everything else is normal

Wenckebach-causes

can be seen in athletes

not necessarily a sign of disease

Mobitz type II

-More P waves than QRS

-No progressive lengthening of PR

*strained relationship, when husband comes home he's on time, but there's frequent nights he doesn't come home*

Key finding of Mobitz II

PR interval is the same when the husband (QRS) DOES come home

3rd degree AV block

atria and ventricles beat independently of each other

(P waves have no relation to QRS waves)

*Husband and wife stop talking*

3rd degree block- findings

ventricular rate < atrial

rhythm irregular

P waves normal

QRS- wide or narrow

PR, P:QRS = not measurable

3rd degree block- causes

life threatening

CAD, Acute MI

If R is far from P then you have a ...

first degree

Longer, longer, longer, drop, then you have a...

Wenkebach

if some P's don't get through then you have a...

Mobitz II

if P's and Q's don't agree then you have a...

3rd degree

Pre-Excitation Syndrome: WPW

Extra pathway between atria and ventricles, skips the AV junction and PRE-EXCITES the ventricles