Cardiology Flash Cards

Front 1

Phases of myocardial cell action potential

Back 1

Phase 4 - negative resting membrane potential; balance of Na+ in and K+ out
Phase 0 - depolarization, Na+ in
Phase 1 - K+ out
Phase 2 - Plateau; Ca2+ in; cell is refractory
Phase 3 - repolarization

Front 2

phases of the pacemaker action potential

Back 2

Higher resting membrane potential
Phase 4 - Ca2+ leak into cell, causing it to reach threshold on it's own
Phase 0(2) - slow Na+ and Ca2+ channels open --> slow activation and short AP
Phase 3 - Repolarization; K+ out

Front 3

Einthoven's Triangle

Back 3

Leads I, II and III create a triangle

Lead I - RA to LA
Lead II - RA to LL
Lead III - LA to LL

Front 4

Augmented Leads

Back 4

Lead aVR (perp III) - LA/LL to RA
Lead aVL (perp II) - RA/LL to LA
Lead aVF (perp I) - RA/LA to LL

Front 5

Chest Leads

Back 5

perpendicular to the frontal plane
combines all the limb electrodes as a negative electrode and the positive is placed at different locations on the chest wall
CV5RL - 5ICS R of sternum
CV6LL - 6ICS L of sternum
CV6LU - 6ICS CC junction
CV10 - between scapulae

Front 6

Standardized ECG protocol

Back 6

- RL recumbency with limbs perpendicular to body
- Limb electrodes placed just distal to elbows and stifles
- paper speed 50 mm/sec, sensitivity 10 mm/mV

Front 7

P wave

Back 7

atrial depolarization

Front 8

PR interval

Back 8

time of conduction from SA node to ventricles
AV node represents 75% of this interval

Front 9

QRS complex

Back 9

ventricular depolarization

Front 10

Q wave

Back 10

first negative deflection
interventricular septal activity

Front 11

R wave

Back 11

first positive deflection following P wave
Predominant wave form in left-facing leads (I, II, aVF, aVL, CV6LL, CV6LU)

Front 12

S wave

Back 12

first negative deflection following a positive deflection

Front 13

T wave

Back 13

ventricular repolarization

Front 14

QT interval

Back 14

time of total ventricular activity

Front 15

ST segment

Back 15

area from end of QRS to beginning of T wave

Front 16

elevation or depression of ST segment

Back 16

ischemia

Front 17

alteration of T wave

Back 17

electrolyte abnormalities (ie hyperkalemia

Front 18

larger than normal S wave

Back 18

right heart enlargement

Front 19

Standard sensitivity

Back 19

10 mm/mV

Front 20

Instantaneous Heart Rate Calculation

Back 20

Count the number of mm between two consecutive R waves and divide into 3000 (@50mm/s) or 1500 (@25mm/s)

Front 21

Standard Heart Rate Calculation

Back 21

Count the number of R waves in a given period of time and multiply to equal 60 sec.

helpful with gradual rate changes over time, inaccurate for very short lasting arrhythmias

Front 22

Steps in approach to the ECG

Back 22

1. Note the Basics
2. Calculate heart rate
3. Determine overall rhythm
4. Identify specific wave forms
5. Assess the ventricular MEA
6. Measure individual waves and intervals

Front 23

Variation in HR with respiration

Back 23

(respiratory) sinus arrhythmia

Front 24

Irregular arrhythmia

Back 24

absolutely no pattern to the R-R variation (atrial fibrillation)

Front 25

How do you find the MEA?

Back 25

1. Determine the most isoelectric lead
2. Idendify the lead that is perpendicular to the isoelectric lead
3. Determine if the lead in step 2 is net positive or net negative
4. Assign the MEA in degrees from the frontal plane chart

Front 26

Which lead is perpendicular to Lead I?

Back 26

Lead aVF

Front 27

Which lead is perpendicular to Lead II

Back 27

Lead aVL

Front 28

Which lead is perpendicular to Lead III

Back 28

Lead aVR

Front 29

Increased height of P wave in Lead II

Back 29

RA enlargement

Front 30

Increased width of P wave in Lead II

Back 30

LA enlargement

Front 31

Increased height of R wave

Back 31

LVE

Front 32

Increased height of S wave

Back 32

RVE

Front 33

T wave >25% height of R wave in Lead II

Back 33

suggestive of LVE in dogs

Front 34

Interrupted PR interval in Lead II

Back 34

Heart block

Front 35

Prolonged PR interval in Lead II

Back 35

AV nodal disease

Front 36

Prolonged QRS duration in Lead II

Back 36

heart enlargement or conduction disturbance

Front 37

Prolonged QT interval in Lead II

Back 37

Hypocalcemia or hypokalemia
Conduction disturbances

Front 38

QT interval shortened in Lead I

Back 38

Hyperkalemia or hypercalcemia

Front 39

J-point

Back 39

when the QRS returns to baseline - the true baseline

Complete myocardial depolarization - no voltage potential

Front 40

Elevated J-point

Back 40

subepicardial injury from ischemia

Front 41

J-point depression

Back 41

Subendocardial injury from ischemia

Front 42

Normal Canine HR

Back 42

60-120, up to 200 in puppies

Front 43

Normal Canine Rhythms

Back 43

Sinus rhythm
Respiratory sinus arrhythmia
Wandering pacemaker

Front 44

Normal canine MEA

Back 44

40-103

Front 45

Normal Feline HR

Back 45

140-240

Front 46

Normal Feline Rhythms

Back 46

sinus rhythm
sinus tachycardia

Front 47

Normal Feline MEA

Back 47

0-160 degrees