HBIO 420 L lab 2 quiz

Information we get from 12-lead ECG (what is incorrect)

anatomical orientation of heart in the body

relative thinness of the heart muscle and size of ventricles

previous damage to the heart

Acute MI

relative thickness and chamber size

Correct what doesn’t belong

Information we get from rhythm strip

Presence of arrthymias

Irregular/premature beats

presence of any blocks not arrythmias

exercise increases heart rate → o2 demand by heart →

ischemia (if CAD is present) → ST-segment depression

impulse originates at the

SA node @ R. atrium starting wave of depolarization

Spreads across left and…

r. atria (atria depolarize & contract)

wave of depolarization goes into

AV Junction , pauses for 0.13 s to wait for atrial contraciton/ventricular filling to complete

Goes down the l. r. ____

bundle branches

carries stimulus → ventricles heart apex then outward to…

after bundle branches →

Purkinje fibers on both sides then→

After Purkinje Fibers →

left and right ventricles

-depolarize, contract

after ventricles depolarize, they…

repolarize, relax, cycle restarts

An uwpward deflection/wave is

positive

A downward deflection/wave

negative

A deflection/wave that rests on the baseline

isoelectric

A deflection/wave that is partially negative is and positive is

biphasic

Sinus node impulse precedes ____ but not visible on ECG

P wave

P wave

represents atrial depolarization (contraction)

small deflection b4 QRS complex

P-R interval

measured from start of P wave to beginning of QRS

Time it takes for stimulus → atria → pass thru AV junction

QRS COMPLEX REPRESENTS…

ventricular depolarization (contraction)

QRS width represents

time req for a stimulus → spread thru ventricles

Does every QRS have a Q wave, R, and an S wave

no

First deflection of QRS = negative

Q-wave

First positive deflection in QRS is

R wave

A negative defleciton following R wave is

an S wave

Atrial depolarization occurs but is hidden

in QRS complex

ST measurement

from end of Qrs to start of T wave

ST segment marks

depolarization beginning

A normal ST segment is

isoelectric

J point

junction between QRS complex and beginning of the ST segment

T wave

Represents ventricular depolarization

QT interval

measure from the beginning of the Q wave to the end of the T wave

QT interval reps…

ventricular refractory period (time to depolarize then depolarize)

U wave

small deflection after T wave

final phase of ventricular repolarization

_______ detect voltages of the cardiac currents donated to these locations

electrodes

Each lead is measuring the same event (one cardiac cycle)

at the same time but lead view it from a different angle

Lead I

La -RA

Lead 2

LL - RA

Lead III

LL - LA

Basic laws of ECG correct

A positive deflection will not appear if any lead if the wave repolarization spreads toward → positive pole of lead

A negative deflection appears if any lead if wave of depolarization spreads toward → negative of that lead

A biphasic deflection will appear if depolarization spread to left angles to any lead axis

a positive deflection will appear if (Depolarization)

r. angle

______ or voltage of ECG waves is measured vertically

Amplitude

(duration) is recorded horizontally

Width

ECG chart paper moves at….

Each mm of ECG paper is = ______

25mm/s

0.04 s

<60bpm

>100bpm

bradycardia

tachycardia

PAC

impulse originates in atria, but not from SA node

normal P-waves (or not visible)

normal QRS width

PVC

impulse originate @ ventricles

no P-wave, wide, aberrant QRS >0.12s

T-wave and QRS point app directions

3+ ___’s = ventricular tachycardia

Unifocal PVCs

originate from same ectopic focus in ventricles

PVC’s that look the same

Multifocal PVC’s

originate from more than one ectopic focus in ventricles

PVC’s that look different