Electro Final Exam

V1 location

4th intercostal space to the right of the sternum

-negative deflection

V2 location

4th intercostal space to the left of the sternum

-mostly negative deflection

V3 location

-located midway between lead V2 and V4

V4 location

fifth intercostal space in midclavicular line

-positive deflection

V5 location

fifth intercostal space at anterior axillary line

-positive deflection

V6 location

located horizontally level with V4 and V5 at midaxillary line

-positive deflection

What does Phase 0 represent

represents depolarization (electrical systole)

What does Phase 1&2 represent

absolute refractory period (electrical systole)

What does Phase 3 represent

relative refractory period (electrical systole)

What does Phase 4 represent

nonrefractory period (electrical diastole)

What is the rate of a 1st degree AV block

1st degree AV block

normal, 60-100bpm

are the P-P and R-R intervals normal in 1st degree AV block

1st degree AV block

both P-P and R-R intervals are normal

is the P wave normal in 1st degree AV block

yes, the P wave is normal in 1st degree AV block

what is the PR interval in 1st degree AV block

1st degree AV block

greater than .20 seconds

what is the QRS duration of 1st degree AV block

1st degree AV block

.06-.10 seconds

what is the atrial and ventricular rates of 2nd degree AV block Mobitz I (wenckeback)

2nd degree AV block Mobitz I

Atrial rate- 60-100bpm

Ventricular rate- slower than atrial

are the P-P and R-R intervals normal in 2nd degree AV block

Mobitz I

2nd degree AV block Mobitz I

P-P interval is regular

R-R interval is irregular

is the P wave normal in 2nd degree AV block Mobitz I

yes, the P wave is normal in 2nd degree AV block Mobitz I

what is a 2nd degree AV block Mobitz II also called

classical heart block

What is the rate for 2nd degree AV block Mobitz II

2nd degree AV block Mobitz II

atrial: 100bpm

ventricular rate is slower that atrial

Are the P-P internal and R-R interval waves normal in 2nd degree AV block Mobitz II

P-P interval is normal

R-R interval is irregular

is the P wave in 2nd degree AV block Mobitz II normal

the P wave in 2nd degree AV block Mobitz II is normal

What is the PR interval in 2nd degree AV block Mobitz II

2nd degree AV block Mobitz II

PR interval: .12 - .20

What is the QRS duration in 2nd degree AV block Mobitz II

2nd degree AV block Mobitz II

QRS duration: .06-.10

What is the 3rd degree AV block also called

complete heart block

what is the rate of a 3rd degree AV block

atrial: 60-100bpm

ventricular: 20-40bpm

are the P-P intervals R-R intervals normal in a 3rd degree AV block

both P-P and R-R intervals are normal in 3rd degree AV block

is the P wave normal in 3rd degree AV block

the P wave is normal, but buried within the QRS

what is the PR interval in 3rd degree AV block

the PR interval is not constant. A long interval followed by a short interval

what is the QRS duration during a 3rd degree AV block

the QRS may or may not be within normal limits in a 3rd degree AV block

What is the Rate in a PAC

rate in a PAC is 60-100bpm

What is the PR interval in a PAC

PAC PR interval: .12-.20

What is the QRS duration in a PAC

QRS duration in a PAC: .06-.10

Conduction system pathway

SA node, AV node, Bundle of HIS, left & right bundle branches, Purkinje Fibers

AV node location

right side of IAS, immediately behind TV, near opening coronary sinus

Bundle of HIS location

right side of IAS just above the ventricle

SA node location

upper posterior portion of the RA

Bundle Branches location

runs along right side of IVS

What do the Internodal pathways do

they spread impulses through the RA to the ventricles

what are the 3 parts of the internodal pathway

Anterior

middle (Wenckebach)

Posterior (Thorel’s)

Automaticity

ability to generate electrical impulses independently

Conductibility

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

Excitability

ability to respond to an electrical stimulus

Contractility

ability of myocardial cells to contract when stimulated by an electrical impulse

where is the heart located

middles of the thoracic cavity (mediastinum)

Systemic circulation

oxygenated blood from lungs to body

what are the 2 components of the heart

electrical and mechanical

Pulmonic circulation

deoxygenated blood from the body to the lungs

Absolute refractory period

unable to excite cells

Relative refractory period

cells can be excited, but only by a stimulus that is much stronger than normal

Nonrefractory period

cell has returned to a resting state

What is a pacemaker

it’s an artificial pulse generator

function of pacemakers

delivers electrical current to the heart to stimulate depolarization

Components of pacemakers

a pulse generator and pacing leads

unipolar electrodes

one pacing electrode (negative) located at distal tip

Negative electrode is in contact with the heart and pulse generator

bipolar electrode

contains a positive and negative electrode at distal tip of pacing lead wire

fixed rate mode

continuously discharges at a set rate - usually 60-80 bpm depending on patient’s heart rate

What does a fixed rate mode NOT do

doesn’t sense the patient’s cardiac rhythm

what is a fixed rate pacemaker called

asynchronous pacemaker

demand mode

discharges only when pt’s heart rate drops below pacemakers preset rate

what is a demand mode pacemaker also called

synchronous and noncompetitive pacemaker

What does a demand mode do

its senses a patient’s cardiac rhythm

what distinguishes bipolar electrodes from unipolar electrodes

unipolar contains only an negative electrode. Bipolar electrodes contain both negative and positive electrodes 

permanent pacemakers

implanted in the body

temporary pacemakers

the pulse generator of a temporary pacemaker is located externally

ventricular pacing

stimulates the ventricles when the heart’s natural conduction system fails to generate adequate ventricular depolarization

Dual chamber pacing (DDD pacemaker)

paces both the atrium and ventricles - one lead placed in the RA and the other in the RV

transcutaneous pacing

recommend choice in emergency cardiac care - least invasive - attaching two large pacing electrodes to the skin surface of the patient's outer chest wall - the electrical signal passes through the chest wall to the heart

Ion exchange’s part 1

sodium gates open fast, sodium is coming into the cell, making the inside of the cell more positive

ion exchange’s part 2

calcium gates open, calcium trickles in while some potassium comes out

ion exchange’s part 3

calcium gates close, potassium gates are still open, as it flows out, the inside of the cell becomes more negative. it’s now ready for the next beat

magnesium’s role in ion exchange’s

magnesium helps the movement of the ions across cardiac cell membranes