ECG derivations and position types

Derivations In our heart there is a permanent flow of differently charged particles (ions). This redistribution in turn generates different, electrical potentials. Through individual recordings, these “electrical heart currents” can be measured from different perspectives and levels.

Combined, the recordings provide a comprehensive picture of the condition of the heart muscle and its conduction system. Usually, a 12-channel ECG is used in Germany, which can register twelve leads simultaneously. These include: 1) Einthoven lead (frontal plane): This belongs to the classic bipolar lead for the extremities, since the voltage is determined between two equal arm or leg electrodes.

A distinction is made between: 2) Goldberger lead (frontal plane): In this type of limb lead, two electrodes of the Einthoven leads are connected together via a resistor to form a single indifferent electrode, i.e. a kind of electrical “zero point”. This creates leads between the zero point and the remaining electrode. They are called 3) Wilson leads (horizontal plane): In contrast to the two previous leads, the six electrodes on the chest wall are used here.

They are called V1-V6. If certain pathological events are suspected, such as an infarction of the posterior wall of the heart, further leads can be created by using additional electrodes. Position types By position type, the physician understands the main vector of the electrical axis of the heart, which can be determined in the ECG using the Cabrera circuit.

The electrical axis of the heart is essentially determined by the position of the heart in the body and the heart muscle mass. Therefore the determination of the type of position is an important aspect of the ECG analysis. A distinction is made between the following types of position: Link type This is the most common type of position in healthy adults over 40 years of age.

This type of position can also be observed when the left half of the heart is enlarged (left ventricular hypertrophy), for example in the context of high blood pressure. Pregnant women also sometimes have a left heart type. Indifference type The most common position type in young, heart-healthy adults; therefore it is also called “normal type”.

Steep type Occurs in children, adolescents and very slim people. It can have disease value in the context of, for example, pulmonary emphysema. Right type Occurs in healthy infants, very slim adults and deep inhalation.

Also observed in the context of congenital heart defects or enlargement of the right half of the heart (right heart hypertrophy). Overexcited left type or right type always have disease value, for example, in congenital heart defects or heart attack.

Derivation I between right and left arm,
Derivative II between right arm and left leg and
Derivative III between left arm and left leg.
Derivation aVR between right arm and the interconnected electrodes of left arm and left leg,
Derivation aVL between left arm and the interconnected electrodes of right arm and left leg and
Derivation aVF between the left foot and both arm derivations.