Electrocardiogram (ECG) & Blood Pressure

1.0Electrocardiogram

• ECG is a graphical representation of the electrical activity of the heart during a cardiac cycle.
• ECG stands for Electrocardiogram.
• Developed by Willem Einthoven
• Device used is Electrocardiograph.
• To obtain a standard ECG a patient is connected to the machine with three electrical leads (one to each wrist and to the left ankle) that continuously monitor the heart activity. 
• For a detailed evaluation of the heart's function, multiple leads are attached to the chest region. 
• In standard ECG, each peak in the ECG is identified with a letter from P to T that corresponds to a specific electrical activity of the heart.

Diagrammatic Presentation of a Standard ECG

Details of Different Waves in ECG

Wave	What it corresponds
	Represents electrical excitation or depolarization of atria, which leads to contraction of both the atria.
	Represents depolarization of ventricles, which initiates the ventricular contraction. The contraction starts slowly after Q and marks the beginning of the systole.
	Represents repolarization of ventricles, which leads to relaxation of both the ventricles.

By counting the number of QRS complexes that occur in a given time period, one can determine the heart beat rate of an individual.

Significance of ECG

ECG is of a great clinical significance as any deviation from this shape indicates a possible abnormality or disease.

2.0Blood Pressure

Blood pressure is the pressure exerted by the flowing blood on the elastic walls of arteries. 

Blood-pressure is measured in two stages:

Systolic Pressure (Pumping Pressure)

It is the higher limit of blood pressure that shows the state of heart contraction (systole). For human this limit is 120 mm Hg (normal).

Diastolic pressure (Resting Pressure)

It is the lower limit of B.P. that shows the state of heart relaxation (Diastole). For human this limit is 80 mm Hg (normal).

The instrument by which we can measure B.P. is called sphygmomanometer.

In man B.P. is measured in the brachial artery of arm or in radial artery.

Normal B.P. of a healthy person is 120/80 mm Hg.

Age : B.P. increases as the age advances. 

3.0Pulse

The pulse is felt in the radial artery present in the wrist of a human. It is also felt in the artery of neck region. The graph of pulse of an artery is marked by an instrument that is called sphygmograph.

Pulse pressure is the pressure difference which generates a pulse. This is systolic minus diastolic B.P.

4.0Also Read