Heart rythmicity-Exam 2

Question 1

Axis for lead I?

Answer 1

2 electrodes on 2 arms
right arm: negative
Left arm: positive
Direction= 0 degree

Question 2

Axis for lead II?

Answer 2

2 electrodes: 1 right arm, and left leg.
Right arm: negative
Left leg: positive
Direction= 60 degrees compare to lead I

Question 3

Axis for lead III?

Answer 3

2 electrodes: left arm and left leg
left arm: negative
Left leg: positive
Direction: 120 degrees compare to lead I

Question 4

Voltage recorded

Answer 4

Voltage recorded is low if vector in the heart in a direction perpendicular to the lead voltage.

Voltage recorded in its entirety if vector in the heart as same axis as the axis of the lead

Question 5

What is instantaneous vector?

Answer 5

Summated vector of the generated potential at a particular instant

Question 6

What is a reference vector?

Answer 6

Horizontal vector that extends towards a person’s left side

equal to 0 degrees

Question 7

Vectorial analysis for T-wave

Answer 7

Normal T-Wave in all 3 bipolar lead is positive as in most normal QRS complex

Question 8

Vectorial analysis of P-wave

Answer 8

ECG positive in all 3 leads

Question 9

Vectorial analysis for atrial T-wave

Answer 9

Obscured by QRS wave
Spread of depolarization through atrial muscle slower than in ventricles
Sinus node area is first to be repolarized

Question 10

What is the Mean Electrical Axis?

Answer 10

Direction of the electrical potential (negative to positive) from the base of the ventricles towards the apex
Equal 59 degrees

Question 11

Abnormal ventricular conditions that cause axis deviation?

Answer 11

Change in position of the heart in the chest
Hypertrophy of one ventricle
Bundle branch block
Fluid in pericardium
Pulmonary emphysema

Question 12

What is an increased voltage in the standard bipolar leads?

Answer 12

High voltage ECG occur when sum of the voltages of all he QRS complexes of the 3 standard leads is greater than 4 mV.
Common in hypertrophy of ventricle.

Question 13

What caused decreased voltage ?

Answer 13

Cardiac myopathies

conditions surrounding heart

Question 14

Patterns of QRS complex

Answer 14

Normal QRS last 0.06 to 0.08 seconds

In hypertrophy or dilation of ventricle QRS prolonged from 0.09 to 0.12 seconds

Question 15

What are the conditions causing bizarre complexes ?

Answer 15

Destruction of cardiac muscle and replacement by scar tissue

Multiple small local blocks in the conductions impulses in the Purkinje system

Question 16

What is Current of injury?

Answer 16

Cardiac abnormalities caused part of the heart to be partially or totally depolarized.
Current of injury flows between the pathologically repolarized and the normally polarized areas even between heartbeats

Question 17

What are abnormalities causing current of injury?

Answer 17

Mechanical trauma
Infectious processes
Ischemia (most common cause)

Question 18

What is a J-point?

Answer 18

Reference point for analyzing current injury

Question 19

What is a vector?

Answer 19

Arrows that points in the direction of the electrical potential generated by the current flow.
Arrow head points to the positive direction