Ekg - Localizing The Infarct

Front 1

How many major arterial systems supply blood to the myocardium?

Back 1

two
one supplies the right,
the other the left

Front 2

Name the two main arteries supplying the heart.

Back 2

right coronary artery
left main artery

Front 3

coronary artery that runs between the right atrium and right ventricle and then swings around to the posterior surface of the heart

Back 3

right coronary artery

Front 4

In most individuals, the AV node is supplied by a descending branch of this artery.

Back 4

right coronary artery

Front 5

In about 10% of the population, the AV node is supplied by a branch of this artery.

Back 5

left circumflex artery
(off the left main artery)

Front 6

vessel that supplies the left side of the heart; divides into two arteries

Back 6

left main artery

Front 7

left main artery divides into these two arteries

Back 7

left anterior descending artery (LAD)
left circumflex artery

Front 8

artery that supplies the anterior wall of the heart and most of the interventricular septum

Back 8

left anterior descending (LAD)

Front 9

artery that runs between the left atrium and the left ventricle and supplies the lateral wall of the left ventricle

Back 9

circumflex artery

Front 10

Why is localization of an infarct important?

Back 10

Prognosis and therapy are in part determined by the location of the infarct.

Front 11

general anatomic categories of infarctions

Back 11

inferior infarctions
lateral infarctions
anterior infarctions
posterior infarctions
(combinations, eg. "anteriolateral")

Front 12

Almost all myocardial infarctions involve this part of the heart.

Back 12

left ventricle

Front 13

True or False:
Frequently, MI does not effect the left ventricle.

Back 13

False.
Almost all MIs involve the left ventricle.

Front 14

In addition to the left ventricle, some inferior infarctions involve a portion of the ______.

Back 14

right ventricle

Front 15

True or False:
Left ventricle is most vulnerable to a compromised blood supply.

Back 15

True.

Front 16

In which leads do the electrocardiographic changes of infarction occur?

Back 16

only in those leads overlying or near the site of infarction

Front 17

infarction that involves the diaphragmatic surface of the heart

Back 17

inferior infarction

Front 18

infarction that is often caused by occlusion of the right coronary artery or its descending branch

Back 18

inferior infarction

Front 19

In which leads can an inferior infarction can be seen?

Back 19

the inferior leads
(II, III, AVF)

Front 20

infarction that involves the left wall of the heart

Back 20

lateral infarction

Front 21

infarction often due to occlusion of the left circumflex artery

Back 21

lateral infarction

Front 22

In which leads can a lateral infarction be seen?

Back 22

lateral leads
(I, AVL, V5, V6)

Front 23

infarction that involves the front surface of the left ventricle

Back 23

anterior infarction

Front 24

infarction usually caused by occlusion of the left anterior descending artery

Back 24

anterior infarction

Front 25

In which leads can an anterior infarction be seen?

Back 25

any of the precordial leads
(V1 through V6)

Front 26

infarction that involves the rear surface of the heart and is usually caused by the occlusion of the right coronary artery

Back 26

posterior infarction

Front 27

In which leads can a posterior infarction be seen?

Back 27

as reciprocal changes in the anterior leads
especially V1

Front 28

What is a 15 lead EKG?

Back 28

An EKG with three extra leads for assessing posterior infarction. (rarely used) Extra leads are V8 and V9 (back) and V4R (right precordial).

Front 29

True or False:
Coronary anatomy can vary markedly among individuals, and the precise vessel involved may not always be what one would predict from the EKG.

Back 29

True.

Front 30

In which leads may reciprocal changes be seen in inferior infarctions?

Back 30

anterior and left lateral

Front 31

Which respective leads would show characteristic and reciprocal evidence of an inferior infarction?

Back 31

changes: II, III, AVF

reciprocal changes: anterior and left lateral leads

Front 32

Which respective leads would show characteristic and reciprocal evidence of a lateral infarction?

Back 32

changes: I, AVL, V5, V6

reciprocal changes: inferior leads

Front 33

Which respective leads would show characteristic and reciprocal evidence of an anterior infarction?

Back 33

changes: precordial (V1-V6)

reciprocal changes: inferior leads

Front 34

Which respective leads would show characteristic and reciprocal evidence of a posterior infarction?

Back 34

characteristic changes: none, unless posterior leads are placed

reciprocal changes: anterior precordial leads, especially V1

Front 35

Although in most infarctions, Q waves remain for the life of the patient, what is the case with inferior infarctions?

Back 35

In about 50% of cases, Q waves disappear within half a year. (This is why small inferior Q waves *may* point to an old inferior infarction in which the Q waves have shrunk.)

Front 36

What may the presence of small Q waves inferiorly indicate?

Back 36

May be an old inferior infarction; may be nothing. Clinical history of the patient must be your guide.

Front 37

In which leads are reciprocal changes from lateral infarctions seen?

Back 37

inferior leads

Front 38

In which leads are reciprocal changes from anterior infarctions seen?

Back 38

inferior leads

Front 39

LAD occlusion may precipitate this event.

Back 39

anterior infarction

Front 40

Which leads may show characteristic changes in an anteriolateral infarction?

Back 40

precordial leads
leads I and AVL

Front 41

True or False:
Loss of electrical forces anywhere in the heart will necessarily produce a Q wave in all leads except AVR.

Back 41

False.
The loss of anterior electrical forces in anterior infarction is not always associated with Q wave formation.

Front 42

What can be said about precordial R wave progression in anterior infarctions?

Back 42

There may be a loss or dimishiment of the normal pattern of precordial R wave progression to indicate infarction, even if no Q wave are present.

Front 43

In normal hearts, the amplitude of R waves should progress at least ______ per lead as you progress from V1 to V4 or V5?

Back 43

1 mV

Front 44

1mV per lead R wave precordial lead progression typical of normal hearts may vanish with ______ infarctions.

Back 44

anterior

Front 45

True or False:
Even in the absence of significant Q waves, poor R wave progression may signify anterior infarction.

Back 45

True.

Front 46

Term used to describe vanished or diminished amplitude increase of R waves that is normally seen across precordial leads.

Back 46

poor R wave progression

Front 47

True or False:
Poor R wave progression is specific to the diagnosis of anterior infarction.

Back 47

False.
It can be seen often with improper lead placement. It is also seen in right ventricular hypertrophy and in patients with chronic lung disease.

Front 48

In posterior infarction, because we can't look for ST elevation and Q waves in nonexistent posterior leads, we must look for ______ and ______ in the anterior leads, notably V1.

Back 48

ST depression

tall R waves

Front 49

The normal QRS complex on V1 consists of a ______ R wave and a ______ S wave.

Back 49

small

deep

Front 50

What should you look for in V1 in the presence of a posterior infarction?

Back 50

tall R wave with ST depression

Front 51

In V1, the presence of an R wave of greater amplitude than the corresponding S wave is highly suggestive of what?

Back 51

posterior infarction

Front 52

True or False:
In posterior infarction, because the inferior wall usually has the same blood supply as the posterior wall, there will often be evidence of accompanying infarction of the inferior wall.

Back 52

True

Front 53

In addition to posterior infarction, the presence of a large R wave exceeding the amplitude of the accompanying S wave in V1 is also one criterion for the diagnosis of ______.

Back 53

right ventricular hypertrophy

Front 54

How can you tell the difference between the EKG findings characteristic of posterior infarction and right ventricular hypertrophy?

Back 54

Right ventricular hypertrophy requires the presence of right axis deviation, which is not present in posterior infarction.

Front 55

True or False:
Not all myocardial infarctions produce Q waves.

Back 55

True

Front 56

Previously used in relation to non-Q wave infarctions, based on the largely discounted thinking that Q waves relate to the wall thickness of the infarction.

Back 56

transmural infarction
(full thickness)

subendocardial infarction
(inside thickness)

Front 57

the only EKG changes seen with a non-Q wave infarction

Back 57

T-wave inversion and ST segment depression

Front 58

True or False:
A non-Q wave infarction may be either transmural or subendocardial.

Back 58

True.

Front 59

Non-Q wave infarctions have ______ initial mortality rate and ______ risk for later infarction and mortality.

Back 59

lower

higher

Front 60

True or False:
Non-Q wave infarctions behave as incomplete infarctions.

Back 60

True.

Front 61

True or False:
Cardiologists are not overly concerned with non-Q wave infarctions.

Back 61

False.
Cardiologists take aggressive measures to prevent further infarction and death, because the risk of later infarction and mortality is very high.