Physiological Basis for ECG and Basic ECG Flashcards

1
Q

The electrodes report voltage difference in:

A

Regions of either ventricles or atria, but not between them.

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2
Q

The average current flow:

A

Occurs with negativity toward the base of the heart and with positivity toward the apex.

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3
Q

P wave

A

SA nodes cause the atria to depolarize from right to left.

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4
Q

PR interval

A

AV node delays signal.

Beginning of P wave until the beginning of QR.

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5
Q

QRS complex

A

Ventricles depolarize generally from right to left, from apex to base, from interior to exterior.

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6
Q

ST segment

A

Action potential phase 2 delays repolarization of ventricles.
End of QRS until beginning of T wave.

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7
Q

T wave

A

Ventricles repolarize generally from left to right.

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8
Q

On ECG, 5 “large” boxes horizontally equals?

2 “large” boxes vertically?

A

1 sec

1.0 mv

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9
Q

QT interval

A

Beginning of QR until end of T wave.

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10
Q

PR segment

A

End of atrial depolarization until beginning of QRS.

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11
Q

Standard (bipolar) limb leads use:

A
  1. right arm to left arm.
  2. right arm to left leg.
  3. left arm to lower limb.
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12
Q

aVF (augmented vector, foot)

A

Right arm and left arm to lower limb.

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13
Q

aVR (augmented vector, right)

A

Lower limb and lower arm to right arm.

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14
Q

aVL (augmented vector left)

A

Lower limb and right arm to left arm.

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15
Q

Einthoven’s triangle

A

Each limb has + and - polarity and voltage between them.

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16
Q

Mean electrical axis

A

Average direction of spreading AP in ventricles.

Helps to determine morphology/condition of the heart.

17
Q

Normal MEA

A

Both leads I and aVF are positive.

18
Q

If lead I is negative:

A

Right axis deviation
aVF can be positive or negative
RV hypertrophy

19
Q

If lead I is positive, but aVF is negative:

A

Left axis deviation.

LV hypertrophy.

20
Q

Relationship of ECG to cardiac cycle
P wave
QRS complex
T wave

A

P wave begins after atrial contraction.
QRS complex begins before ventricular contraction.
T wave begins before ventricular relaxation.