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Physiology I (Exam II material) > Lecture 7 Cardiac > Flashcards

Lecture 7 Cardiac Flashcards

1
Q

Limb Lead I

A

Negative terminal is connected to the right arm
positive terminal is connected to the left arm
Looks at the heart form left to right

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2
Q

Limb Lead II

A

Negative terminal of ECG is connected to the right arm
Positive terminal of ECG is connected to the left leg
Looks at heart form upper right to lower left

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3
Q

Limb lead III

A

Negative terminal is connected to the left arm
Positive terminal is connected to the left leg
Looks at heart from the upper left to lower left

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4
Q

Einthoven’s triangle

A

Two arms and left leg form apices of triangle

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5
Q

Einthoven’s law

A

If the electrical potentials of any two of the three bipolar limb ECG leads are known at any given instant, the third can be determined by summing the first two

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6
Q

Normally in the ventricles current flows?

A

form negative to positive primarily in the direction form the base of the heart toward the apex for most of the heart cycle until the very end

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7
Q

In recording limb lead I: when the point where the right arm connects to the chest is negative with respect to the point where the left arm connects, the ECG records _______?

A

Positive

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8
Q

In Limb lead II: when the right arm is negative with respect to the left leg the ECG records _________?

A

Positive

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9
Q

Limb Lead III: When the left arm is negative with respect to the left leg, the ECG records _____?

A

Positive

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10
Q

What is the angle for Lead I

A

0 degrees

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11
Q

what is the angle for Lead II

A

60 Degrees

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12
Q

what is the angle for Lead III

A

120 degrees

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13
Q

In term of ECG the a vector is what

A

an arrow that points in the direction of the electrical potential generated by the current flow, with the arrowhead in the positive direction.
The length is proportional to the voltage of the potential

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14
Q

When the vector in the heart is in a direction almost perpendicular to the axis of the lead, the voltage recorded in the ECG of this lead is very _____

A

low

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15
Q

When the heart vector has almost the same axis as the axis of the lead, the _____ voltage of the vector is recorded

A

Entire

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16
Q

What is the instantaneous mean vector

A

The summated vector of the generated potential at a particular instant

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17
Q

_____ is horizontal and extends towards a person’s left side

A

Reference vector

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18
Q

What is reference direction

A

0 degrees

reference vector is horizontal and extends towards a person’s left side

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19
Q

what is the mean electrical axis of the heart

A

+ 59 degrees

20
Q

what results in the apex of the heart remaining positive with respect to the base of the heart

A

The average direction of the vector during spread of the depolarization wave through the ventricles

21
Q

T-Wave Vectorial Analysis

what repolarizes last

A

Endocardial areas

22
Q

T-Wave Vectorial Analysis

Ventricular vector during repolarization is toward ?

A

The apex of the heart

23
Q

The normal T-wave in all three bipolar leads is ______

A

Positive

24
Q

T-Wave Vectorial Analysis

what is the greatest portion of ventricular mass to repolarize first?

A

The entire outer surface of the ventricles, especially near the apex

25
Q

Atrial depolarization begins where

A

at the Sinus node

26
Q

The P-wave is normally ____ in all three leads

A

positive

27
Q

Vector direction of the P-wave is generally in what direction

A

direction of the axes of the three standard bipolar limb leads

28
Q

The spread of depolarization is slower where

A

In the atria than in the ventricles

29
Q

The Atrial T-wave is almost always obscured by what

A

The QRS complex

30
Q

what is the first area to become repolarized

A

The sinus node area

31
Q

At the beginning of repolarization the sinus node is ______ with respect to the rest of the atria

A

Positive

32
Q

A typical ECG may utilize how many leads

A

12 leads

33
Q

Each lead provides what

A

A different perspective on the voltage differences between areas of the heart

34
Q

In addition to the three conventional leads what are the additional leads in a common 12 lead

A

six standard leads (V1-V6)

three augmented leads (aVR, aVL, aVF)

35
Q

what is the mean electrical axis

A

is the direction of the electrical potential (negative to positive) form the base of the ventricles toward the apex

59 degrees

36
Q

what are some abnormal ventricular conditions that cause mean electrical axis deviation

A 
Change in position of the heart in the chest
hypertrophy of one ventricle
bundle branch block
fluid in pericardium
pulmonary emphysema
37
Q

When is a high-voltage ECG said to occur and what is the most common cause

A

when the sum of the voltages of all the QRS complexes of the three standard leads is greater than 4 mV
most common cause is hypertrophy of the ventricle

38
Q

What are the most common causes of decreased voltages in an ECG

A

cardiac myopathies,

caused by conditions surrounding the heart

39
Q

The normal QRS lasts how long

A

0.06 to 0.08 seconds

40
Q

Hypertrophy or dilation of the left or right ventricle can lead to the QRS?

A

being prolonged to 0.09 to 0.12 seconds (nl QRS duration is 0.06-0.09 seconds)

41
Q

what are some conditions that can cause bizarre patterns of the QRS

A

Destruction of cardiac muscle and replacement by scar tissue

multiple small local blocks in the conduction impulses at many points in the Purkinje system

42
Q

Different cardiac abnormalities cause part of the heart

A

To remain partially or totally depolarized all the time

43
Q

Current of injury flows?

A

between the pathologically depolarized and the normally polarized areas, even between heartbeats

44
Q

what are some abnormalities that cause current of injury

A

Mechanical trauma, infectious processes, Ischemia (most common cause)

45
Q

What is the most common cause for current of injury

A

Ischemia

46
Q

What are the effects of current of injury on QRS complex

A

Abnormal negative current flows from infarcted area and spreads toward the rest of the ventricles

47
Q

What is a J point

A

reference point for analyzing current of injury
occurs at the very end of the QRS complex and is the point at which all parts of the ventricle, including the injured areas, have become depolarized

Physiology I (Exam II material) (9 decks)

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