Ecg Leads Flashcards
BIPOLAR LEADS (Standard limb leads)
LEAD I: - ve Right arm, + ve (exploring
electrode) Left arm which is 0 degrees
LEAD II: - ve Right arm, + ve Left foot which is 60 degrees
LEAD III: - ve Left arm, + ve Left foot which is 120 degrees
Unipolar leads
record electrical potential at particular point
Unipolar augmented limb leads: record potential difference between one limb ( exploring electrode) and
the other 2 limbs:
aVR - 150 indifferent electrode is Left arm, Left foot, Left arm, Left foot Right arm
aVL- 30 indifferent electrode Right arm, Left foot, + ve Left arm
aVF + 90° indifferent electrode Right arm, Left arm, + ve Left foot
Unipolar leads
Chest leads: record the potential generated at the site of exploring electrode and the zero electrode
V1 right 4th intercostal space at sternal border V4 left 5th intercostals space midclavicular line (apex)
V2 left 4th intercostal space at sternal border V5 Midway between V4 & V6. (anterior axillary line)
V3 Midway between V2 & V4 V6 left 5th intercostals space midaxillary line
View:
V1 & V2 → view the right ventricle
V3 & V4 → septum & anterior part of left ventricle
V5 & V6 → lateral part of left ventricle
Electrical Axis of the heart=mean QRS= cardiac vector
Is the mean value of depolarization wave, Represented by a vector (has an amplitude & direction)
Normal direction of Electrical Axis of the heart between = (-30°) to (+ 90 )
determination of axis
If both l & lead II are +ve = normal axis
If lead I is +ve & lead II is -ve = left axis deviation
If lead I is -ve and aVF is +ve = right axis deviation
Right axis deviation
more than > + 90 degree
Physiological Long, thin individuals
Pathological Right ventricular hypertrophy
Left axis deviation
less than < -30 degree
Physiological Short, Obese , Pregnancy
Pathological Left ventricular hypertrophy
Inferior surface & Anterior surface
II, III, avf
V1, v2
Antero septal surface & Lateral surface
V3, v4
I, avl, v5, v6
