ECG

ECG

Electrocardiography

An electrocardiogram (ECG) is a simple test that can be used to check your heart's rhythm and electrical activity. Sensors attached to the skin are used to detect the electrical signals produced by your heart each time it beats.

Types of ECG

´  There are three main types of ECG:

´   Resting ECG –

´   Stress Or Exercise ECG-

´  Ambulatory ECG –

 RESTING ECG

´  carried out while you're lying down in a comfortable position

 Stress Or Exercise ECG-

´  carried out while you're using an exercise bike or treadmill

AMBULATORY ECG 

´  The electrodes are connected to a small portable machine worn at your waist so your heart can be monitored at home for one or more days

Electrodes and leads

Electrode name	Electrode placement
RA	On the right arm, avoiding thick muscle.
LA	In the same location where RA was placed, but on the left arm.
RL	On the right leg, lower end of medial aspect of calf muscle. (Avoid bony prominences)
LL	In the same location where RL was placed, but on the left leg.
V1	In the fourth intercostal space (between ribs 4 and 5) just to the right of the sternum (breastbone).
V2	In the fourth intercostal space (between ribs 4 and 5) just to the left of the sternum.
V3	Between leads V2 and V4.
V4	In the fifth intercostal space (between ribs 5 and 6) in the mid-clavicular line.
V5	Horizontally even with V4, in the left anterior axillary line.
V6	Horizontally even with V4 and V5 in the midaxillary line.

POSITION OF ECG LEADS 

When an ECG is used

´  An ECG is often used alongside other tests to help diagnose and monitor conditions affecting the heart.

´  It can be used to investigate symptoms of a possible heart problem, such as chest pain, suddenly noticeable heartbeats (palpitations), dizziness and shortness of breath.

AN ECG CAN HELP DETECT

´  Arrhythmias – where the heart beats too slowly, too quickly, or irregularly

´  Coronary heart disease – where the heart's blood supply is blocked or interrupted by a build-up of fatty substances

´  Heart attacks – where the supply of blood to the heart is suddenly blocked

´  Cardiomyopathy – where the heart walls become thickened or enlarged

´  A series of ECGs can also be taken over time to monitor a person already diagnosed with a heart condition or taking medication known to potentially affect the heart.

Limb leads

´  Leads I, II and III are called the limb leads. The electrodes that form these signals are located on the limbs—one on each arm and one on the left leg. The limb leads form the points of what is known as Einthoven's triangle.

´  Lead I is the voltage between the (positive) left arm (LA) electrode and right arm (RA) electrode

´  I=LA-RA

´  Lead II is the voltage between the (positive) left leg (LL) electrode and the right arm (RA) electrode:

´  II=LL-RA

´  Lead III is the voltage between the (positive) left leg (LL) electrode and the left arm (LA) electrode:

´  III=LL-LA

Contiguity of leads

´  Each of the 12 ECG leads records the electrical activity of the heart from a different angle, and therefore align with different anatomical areas of the heart. Two leads that look at neighboring anatomical areas are said to be contiguous.

 RISKS FACTORS OR SIDE EFFECTS

´  An ECG is a quick, safe and painless test. No electricity is put into your body while it's carried out.

´  There may be some slight discomfort when the electrodes are removed from your skin – similar to removing a sticking plaster – and some people may develop a mild rash where the electrodes were attached.

´  There's a possibility the stress placed on your heart during an exercise ECG could cause you to experience problems such as chest pain, an irregular heartbeat, or even a heart attack in some cases, but you'll be monitored carefully during the test and it can be stopped if you start to feel unwell.

ECG LEAD PHOTO