Anesthesia: Electrocardiography (ECGs)

what is an ECG?

measurement of the electrical activity of the heart

will display the electrical impulses as waveforms

what is the P wave

the firing of the SA node and atrial depolarization

what is the QRS complex

depolarization of the ventricles

what is the T wave

repolarization of the ventricles

what is the PR interval

measured from the beginning of the P wave to the beginning of the QRS complex

what is the QT interval

measured from the beginning of the QRS complex to the end of the T wave

what is the ST segment

measured from the end of the QRS complex to the beginning of the T wave

how to read ECG on paper

sweep speed ex: 25 mm/sec

find boxes ex: 30 large boxes

count QRS ex: 5 QRS

find your rate ex: 5 beats/6 sec

convert to beats/min ex: 5\*10= 50 beats/min

patients heart rate is 50 bpm

Look at ECG Paper practive

paper practice

in a normal ECG what is normal to see

P wave in front of each QRS complex

QRS complex following each P wave

All Ps and QRS look the same and normal

P-R intervals are the same and normal in duration

R-R intervals are the same

how to remember to place the electrodes

white and black on jugular in the horse

red over the heart on the horse

white on right (right forelimb)

smoke over fire (black on forelimb red on hindlimb in the dog)

what is seen in sinus arrhythmia

P wave in front of each QRS complex

QRS complex following each P wave

Ps and QRSs look the same and normal

P-R intervals are the same and normal duration

__R-R intervals are NOT the same__

what is sinus arrhythmia

a longer than normal space between QRS complexes

corresponds with breathing

during inspiration, the heart rate speeds up

during expiration, the heart rate slows down

regularly in athletic, sedated, or relaxed patients

what is commonly seen in first degree AV block

A P wave in front of each QRS complex

A QRS complex following each P wave

Ps and QRSs look the same and normal

__P-R intervals are NOT the same and at a normal duration__

R-R intervals are the same

what is a first degree AV block

conductive delay of the AV node

P-R interval longer than 0.2 seconds

usually seen if a paper strip is printed and measured

not usually treated

what is common to see with a second degree AV block

A P wave in front of each QRS complex

__A QRS complex is NOT following each P wave__

Ps and QRSs look the same and normal

__P-R interval is NOT the same and normal in duration__

__R-R intervals are NOT the same__

what is a second degree AV block

P-wave with no corresponding QRS complex

AV node fires but the signal is not conducted to the SA node

ventricles never depolarize

commonly seen under anesthesia

treated with an anticholinergic

what is Mobitz type 1

second degree AV block

also known as Wenckebach rhythm

further further further dropped it is called the Wenckebach

P-R interval gradually increases until the QRS complex is dropped

what is Mobitz type 2

second degree AV block

no lengthening of the P-R interval

sporadic dropped complexes

what is common to see in third degree AV block

A P wave in front of each QRS complex

__A QRS complex is NOT following each P wave__

__Ps and QRSs do NOT look the same and normal__

__P-R intervals are NOT the same and at a normal duration__

R-R intervals are the same

what is a third degree AV block

complete heart block

no communication between the SA node and the AV node

atria are depolarizing at their own rate

the ventricles are depolarizing at their own, separate rate

treated with a pacemaker

what is common in an accelerated idioventricular rhythm (AIVR)

__A P wave is NOT in front of each QRS complex__

__A QRS complex is NOT following each P wave__

__Ps and QRSs do NOT look the same and normal__

__P-R intervals are NOT the same and at a normal duration__

R-R intervals are the same

what is the accelerated idioventricular rhythm (AIVR)

wide, irregular QRS complexes

P waves and T waves are absent

associated with increased vagal tone and decreased sympathetic tone

anticholinergics can help override in some cases

treatment of the underlying cause is necessary for long term

what is common in ventricular escape beats

__P wave is NOT in front of each QRS complex__

QRS complex are following each P wave

__Ps and QRSs are NOT the same and look normal__

__P-R intervals are NOT the same and at a normal duration__

__R-R intervals are NOT the same__

what are ventricular escape beats

wide, strange QRS complex after a long pause

associated with ventricles contracting independently due to lack of impulse from the SA node

can be caused from anesthetic drugs

treat with anticholinergic

what is common with ventricular premature contractions

__P wave is NOT in front of each QRS complex__

QRS complex are following each P wave

__Ps and QRSs are NOT the same and look normal__

P-R intervals are the same and at a normal duration

__R-R intervals are NOT the same__

what are ventricular premature contractions (VPCs)

wide and abnormal ventricular contraction

ventricles contract too early in the heart rhythm

treated sometimes

treated with lidocaine or other antiarrhythmic

what is common with ventricular tachycardia

__P wave is NOT in front of each QRS complex__

__QRS complex are NOT following each P wave__

__Ps and QRSs are NOT the same and look normal__

__P-R intervals are NOT the same and at a normal duration__

R-R intervals are the same

what is ventricular tachycardia

fast, bizarre looking QRS complexes with no P waves or T waves

no/very weak pulses

needs to be treated

\-lidocaine

\-beta blockers

\-calcium channel blockers

\-defibrillation

what is common to see in ventricular fibrillation

__P wave is NOT in front of each QRS complex__

__QRS complex are NOT following each P wave__

__Ps and QRSs are NOT the same and look normal__

__P-R intervals are NOT the same and at a normal duration__

__R-R intervals are NOT the same__

what is ventricular fibrillation

usually fatal arrhythmia

high heart rate with wide, strange QRS complexes

must be treated with defibrillator

what is common to see in atrial fibrillation

__P wave is NOT in front of each QRS complex__

__QRS complex are NOT following each P wave__

__Ps and QRSs are NOT the same and look normal__

__P-R intervals are NOT the same and at a normal duration__

__R-R intervals are NOT the same__

what is atrial fibrillation

looks like artifact

random small waves in between complexes

sign of deeper cardiac disease

further cardiac workup needed and treatment may be warranted

what is common to see in atrial flutter

P wave is in front of each QRS complex

__QRS complex are NOT following each P wave__

__Ps and QRSs are NOT the same and look normal__

__P-R intervals are NOT the same and at a normal duration__

__R-R intervals are NOT the same__

what is atrial flutter

sawtooth, fluttery pattern

sign of deeper cardiac disease

further cardiac workup needed

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normal ECG

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sinus arrhythmia

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first degree AV block

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second degree AV block

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mobitz type 1

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mobitz type 2

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third degree AV block

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accelerated idioventricular rhythm

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ventricular escape beats

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unifocal ventricular premature contractions

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multifocal ventricular premature contractions

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ventricular tachycardia

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ventricular fibrillation

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atrial fibrillation

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atrial flutter