24.Electrocardiogram; analysis of ECG

Question 1

What should be mentioned in this topic?

Answer 1

Electrocardiogram; analysis of ECG:

Electrocardiography (ECG)

Einthoven’s triangle

Analysis of ECG

Types of ECG

Echocardiography

Doppler-Sonography

Question 2

Explain how we use ECG:

(Triangle)

Answer 2

Electrical activity of single myocytes – can only be measured experimentally

However, the sum of the activities of all fibers can be measured on the surface of the body (electro cardio gram; ECG).

“Einthoven’s triangle”
Einthoven 1:
− Right arm – Left arm

Einthoven 2:
− Right arm – Left leg

Einthoven 3:
− Left arm - Left leg

Question 3

Analysis of ecg

(smart å tegne opp)

Answer 3

• *P wave

• **Upward (positive) deflection
,beginning of atrial depolarization. The SA node is depolarized before, but it can’t be detected

PQ segment

On the isoelectric line, total atrial depolarization. A-V conduction.

QRS-complex

-beginning of ventricular depolarization, meanwhile repolarization of atrium already starts.

Q wave

-downwards (stimulus runs from His through the septum and toward (upward) the basis of the heart)

R wave

-max ventricular depolarization. The stimulus runs from endocardium to pericardium and from base to apex. The total ventricular mass is depolarizing.

S wave

-The end of QRS, it is mostly related to the depolarization of the right ventricle.

• *ST segment

• **Isoelectric line on the oscilloscope, ventricles are totally depolarized.

T wave

-beginning of ventricular repolarization. In man & in small animal: points toward upwards, in others towards downwards.

TP segment

• represents the resting phase, following the total repolarization, so the oscilloscope is at the Isoelectric line again,
• during TP segment all the myocytes are (+) outside, while (-) inside

Question 4

Connection between ECG and AP of ventricular muscles

(picture)

Answer 4

Question 5

Analysis of ECG

(picture of heart)

Answer 5

Question 6

Analysis of ECG

(picture of graph)

Answer 6

Question 7

Types of ECG

Answer 7

Unipolar ECG
-RA,LA & LL connected to each other via high

resistance forming 0 potential reference point.

His bundle ECG
electrode goes up to the septum through vein catheter

Esophageal ECG

electrode through esophagus close to the heart:

Vectorcardiography
provides info about the anatomy of the heart.

Question 8

Ultrasonography examination

Answer 8

Provides even more detailed picture about the anatomy of the heart and about the blood flow (Doppler)

Question 9

Ultrasonography examination

(picture)

Answer 9