Electrocardiogram (EKGs)

Toward, upward

If sum of electrical vectors on EKG is __ a lead, it is positive in direction and spike is __

 P wave

SA node fire and depolarization of atria → Atrial systole

(EKG component)

PR Interval

Time between atrial depolarization and ventricular depolarization; reflects conduction through AV node

(EKG component)

Q

Depolarization of interventricular septum (QRS complex)

R

Depolarization of main mass of ventricles (QRS complex)

S

Depolarization towards base of heart (QRS complex)

ST segment

Reflects plateau of action potentials in ventricles → ventricular contraction

(EKG component)

T wave

Ventricular repolarization immediately before ventricular relaxation

(EKG component)

Contraction, initiates

The P-wave does NOT equal atrial __, rather it __ this process

Depolarization, contraction, Ca2+

Events in P-wave

•  Represents atrial __ and initiates atrial __

• Electrical activity going thru atria with high __ (ion) concentration

AV, slowly, contracting

Events in PR Segment

• Delay as signal moves through the __ node

  • AV node __ depolarizing → Not visible since amount of tissue is so small

  • Atria still __

Contraction, spike, atrial

Events in QRS Complex

• Ventricle depolarization and ventricular __

• More cardiac muscle (myocytes) means more charge = illustrated by a visible __

  • Also __ repolarization technically, not visible

Contraction, Ca2+

Events in S-T Interval

• Ventricular __, no net electrical forces

• Ventricles contracting with high intracellular __ levels

Repolarization, Ca2+

Events in T-wave

• Ventricular __

  • ventricles still contracting with high intracellular __ levels

Bump, +, -, inversion

__ patterns in EKG represent differences in charge

• Upward bump reflects _ dipole movement

• Downward bump reflects _ dipole (or an __)

Same, angle, perpendicular

EKG Function

Each EKG lead is “looking” at the __ electrical activity from a different __/perspective

• If net electrical current vector is __ to the lead, there is no deflection on ECG

RA, LA, LL

Limb leads (3)

RA LA, RA LL, LA LL

Classic leads formed by limb combinations - think left/lower more +

__ (-) to __ (+) arm-arm

__ (-) to __ (+) arm-leg

__ (-) to __ (+) arm-leg

aVL

Core lead to LA

left

aVF

Core lead to LL

floor

aVR

Core lead to RA

right

Right, lateral

V1 is (left/right-most)

V6 is (medial/lateral-most)

Positive QRS, vectors

Axis is the degree in the limb leads that has most net __ (+/-) __ complex current

• helps localize net current movement (__) in heart and even localize pathology

Ischemia

When oxygen delivery does not meet tissue demand

Infarct

Occlusion of blood to region of myocardium → necrosis

300/(#big boxes between QRS)

Calculation of rate in EKG done by (math)

P wave

Arrythmias on EKGs are often discernable from an absent _ __ right before QRS complex

60-100, narrow, flat, normal

In NSR

• Rate is between __-__ bpm

• QRS is __, ST is __, T-wave is __

100, narrow, flat, shorter, normal

In Sinus Tachycardia

• Rate is faster than __ bpm

• QRS is __, ST is __ and slightly __, T-wave is __

60, narrow, flat, normal

In Sinus Bradycardia

• Rate is slower than __ bpm

• QRS is __, ST is __ , T-wave is __

Disorganized, ventricular, P, narrow, flat, normal

In Atrial Fibrillation

• __ atrial activity, with coordinated __ contraction

• No _-wave before QRS

• QRS is __, ST is __, T-wave is __

Disorganized, cardiac output, P, QRS, T

In Ventricular Fibrillation

• __ ventricular activity, means no contraction and minimal __ __

• No identifiable _ waves, __ spike, or _ waves

Ischemia, disconnect, P, QRS, widen, inversion

In Complete Heart Block

• __ to vessels suppling AV node

• electrical __ between SA/AV nodes and His-Purkinje-ventricles

• _ waves and __ are unrelated, QRS spike __, and notable T wave __

P, QRS, ST, depressions

In STEMI

• Normal _ wave, narrow __, except __ segment is elevated

• May present with reciprocal __ to ST segment in other leads (complete 12 lead)

ischemic, troponins, depressions, inversion

NSTEMI

• Suspected cardiac __ injury from elevated __ (protein)

• Instead of ST elevations, commonly seen are ST __ or T-wave __

Asystole, PEA

2 conditions of arrest (no pulse = no oxygen delivery)