Electro Exam 2

EKG strip waves

P wave - atrial depolarization

QRS complex- ventricular depolarization

T wave- ventricular repolarization

AVR

voltage between right arm electrode central point between left arm and left leg

AVF

 voltage between left leg electrode central point between Right arm and left arm

AVL

voltage between left arm electrode central point between right arm and left leg

3 fascicles of the left bundle branch

Anterior

Posterior

Septal

what fascicle supplies impulse to the mid sternum

septal fascicle

Branches of internodal pathway

Anterior

Middle aka Wenckeback

Posterior aka Thorel’s

what do the 3 branches of the internodal pathway do

spread impulses through the RA to the ventricles

The AV node is broken down into 3 function regions, what are they

atrial node

nodal

nodal HIS

location of atrial nodal on AV node

upper junctional region or transitional zone

location of the nodal on AV node

midportion of AV node

location of the nodal of HIS on AV node

lower junctional region. fibers of AV node merge gradually with bundle of HIS

Where is the Bundle of HIS located

right side of IAS above ventricles

where does the electrical impulse spread to

endocardium to myocardium

longest and thinnest of the left bundle branch, also spreads impulses to the anterior portions of the left ventricle

anterior fascicle

shortest and thicker of the left bundle branch, also spreads impulses to the posterior and inferior portions of the left ventricle

posterior fascicle

conduction pathway

SA node - AV node - Bundle of HIS - left and right bundle branches - purkinjie fibers

“pacemaker of the heart”

SA node

normal rate for SA node

60-100bpm

normal rate for AV node

40-60bpm

normal rate for purkinjie fibers

20-40bpm

3 types of leads

Standard

Augmented

Precordial

what are the 4 chambers of the heart

2 atrias, left and right

2 ventricles, left and right

what are the valves of the heart

atrioventricular valves

semilunar valves

thebesian valve

Eustachian valve

what are the 2 atrioventricular valves

tricuspid valve

mitral (bicuspid) valve

what are the semilunar valves

pulmonic valve

aortic valve

where is the thebesian valve located

near entrance of coronary sinus

what is the thebesian valve also called

incompetent valve

where is the eustachian valve located

near entrance of the IVC (inferior vena cava)

what is the function of the valves of the heart

to control and maintain blood flow through the body

what type of blood does the right atrium receive

deoxygenated blood (pulmonary circulation- from body to lungs)

what type of blood does the left atrium receive

oxygenated blood (systemic circulation- from lungs to body)

blood flow

SVC-IVC-CS-RA-TV-RV-pulmonary valve-MPA-lungs-4 pulmonary veins-LA-MV-LV-aortic valve-body

3 layers of the heart

epicardium (outer)

myocardium (middle)

endocardium (inner)

what surrounds the heart

pericardium

how much fluid does the pericardium cavity contain

10-50mL

a dilated coronary sinus can be confused for

the descending aorta

3 branches of the aortic arch

Brachiocephalic

Left common carotid artery

left subclavian

what is the higher-pressure chamber

left ventricle

measurement for each small box on an EKG

0.04sec/min

what does the pericardium do

prevent infection, friction and trauma, provides lubrication

what is the cardiac cycle

one complete contraction and relaxation of the heart

stroke volume

amount of blood ejected from the heart each minute

cardiac output

amount of blood pumped into the aorta each minute

Frank Starlings law

the greater the stretch, the greater the contraction, it’s a length tension relationship

where is the SA node located

located in the upper posterior portion of the right atrium

what feeds the bundle of HIS

anterior and posterior descending coronary arteries

what artery supplies blood to the AV node

usually right coronary artery, if not, left circumflex

automaticity

ability to generate an impulse on its own

Excitability

each cell responding to an electrical stimulus

Conductivity

each cell can receive an electrical stimulus and conduct it to an adjacent cell

what is the largest vein that drains into the heart

coronary sinus

what is also known as the resting state

polarized state

What wave form is this

Atrial Flutter

Atrial flutter criteria

P-P interval or flutter-flutter waves are regular and stay consistent

rate: 250-300 bpm

P waves not seen

flutter waves resemble sawtooth or picket fence, best seen in lead II, and III, and well as AVF

PR interval not identifiable

QRS duration- .06-.10 sec

what wave form is this

tachycardia

what wave form is this

Bradycardia

what wave form is this

normal sinus rhythm

what wave form is this

Atrial fibrillation

what wave form is this

sinus (pause) arrest

what wave form is this

Premature atrial contraction (PAC)

what wave form is this

supraventricular dysrhythmias

what wave form is this

Junctional Rhythm

what wave form is this

sinus arrhythmia

tachycardia criteria

100-150bpm

PR interval- .12-.20 sec

QRS duration- .06-.10sec

bradycardia criteria

40-60bpm

PR interval- .12-.20 sec

QRS duration- .06-.10sec

normal sinus rhythm criteria

interval between 2 “P” and 2 “R” waves are consistent in pattern

60-100bpm

PR interval- .12-.20sec

QRS duration- .06-.10sec

Atrial fibrillation criteria

P-P interval not determinable

R-R interval is irregular

atrial rate- 375-700bpm

ventricular rate- 160-180bpm

P wave can’t be identified

PR interval can be identified

QRS duration- .06-.10 sec

Sinus arrest criteria

interval between 2 “P” and 2 “R” waves are consistent in pattern

atria and ventricular rates will be the same, but rate will vary depending on amount of electrical activity in SA node

PR interval- .12-.20sec

QRS duration- .06-.10sec

Premature atrial contraction (PAC) criteria

Rate-atria and ventricles usually 60-100 depending on frequency of PAC’s

P wave configuration- Uniform shape, except for early beat / Early beat may be flattened, notched, biphasic or otherwise unusual. / Early P-wave may be hidden within T-wave.

PR interval- .12-.20 sec

QRS duration- .06-.10 sec

Supraventricular Dysrhythmias (SVT) criteria

ventricular rate- 150-350bpm

R-R wave usually regular

P wave not usually identifiable since it may lie inside T wave

PR interval unable to determine

QRS duration -.06-.10 sec

junctional rhythm criteria

P-P and R-R intervals are regular and have similar intervals.

if P wave is identifiable, rate it’ll be 40-60 bpm

P wave usually inverted

PR interval- if before the QRS complex, will be less than .12 seconds and be constant, otherwise not identifiable

QRS duration- .06-.10 sec

Sinus arrythmia criteria

interval between 2 “P” and 2 “R” waves is irregular

60-100bpm

What does the QRS represent

ventricular contraction

normal QRS duration

.06-.10 sec

normal PR interval

.12-.20 sec

The PR segment is from the beginning of ___to the onset of___

P wave: QRS

V1 location

4th intercostal space to the right of the sternum; negative deflection

V2 location

4th intercostal space to left of sternum; mostly negative deflection

V3 location

on the line midway between V2 and V4

V4 location

midclavicular line 5th intercostal space, positive deflection

V5 location

anterior axillary line, same level as V4; positive deflection

V6 location

mid axillary, same level as V4; positive sternum

What does retrograde-below baseline represent

negative electrical flow

what does antegrade-above baseline represent

positive electrical flow

what is the most accurate way to measure the heart rate

1500 method

what is the 1500 method

dividing 1500 by the number of small squares between two consecutive R waves

what is the impulse that spreads through the RA and the LA, also known as the largest branch

Bachman’s Bundle

Where is the Av node located

on the right side of the IAS, immediately behind the TV and near the entrance of the CS

What when a patient moves / or there is muscle activity during an EKG

somatic interference

what is it called when there is an electrical interference on the EKG

AC interference

coronary circulation

blood is supplied to the tissues of the heart during diastole by the first 2 branches of the aorta as well as the right and left coronary arteries

EKG paper

made up of small and large boxes measured in millimeters

small boxes are 1mm wide and 1mm high

speed of 25mm/sec

on the horizontal axis on the EKG paper

time

on the vertical axis on the EKG paper

amplitude

how to analyze a rhythm strip

assess rate

identify and examine P waves

access intervals

evaluate overall appearance

Determining ventricular rates - method 1

count # of QRS complexes within a period of 6 sec, then x by 10

this gives you a quick estimate of ventricular rate, but not the most accurate

Determining ventricular rates - method 2

count # of large boxes between 2 consecutive R waves, then divide by 300.

Determining atrial rates

count # of large boxes between 2 consecutive P waves, then divide by 300.