Question

Characteristics of the EKG waveforms:

1. A normal PR interval has a normal duration __________________
   1. ST segment is measured from: __________________________________

Answer 1

Answer:

Characteristics of ECG (Electrocardiogram)

ECG is a graphical record of the electrical current and their stimulus produced due to the working of the cardiac muscle fibers. The father of ECH is Einthoven for which he was awarded with the Noble prize as well.

In short the ECG gives us an idea about the normal working of the heart. In order to do so, arbitrarily and randomly the alphabets P, QRS and T are used.

A normal ECG is made of a P wave, a ORS complex and then a T wave.

Characteristic of a P wave: It is a small upward wave which represents the atrial system that is atrial depolarization due to the drainage of blood into the atria (right) from the superior, inferior vena cava and coronary sinuses. Due to which the SA node (pace maker) gets activated thereby leading to their contraction which is recorded in the form of a small upward deflection called as the P wave.

Characteristic of QRS complex: the QRS complex put together represents the ventricular systole or the ventricular depolarization. It begins after the P wave gets over in the form of a small deflection in the downward direction. Reason is that the SA node needs to pass on the information to the AV node (pace setter). There the lag is seen in the form of a downward deflection initially followed by a powerful peak with a greater height. Reason to this being the ventricular systole are more powerful as their walls are thicker and the work load on them is way more as compared to the atrium.

Characteristic of a T wave: The T wave is dome shaped and it characterizes the emptying of the ventricles. That is when the blood from the ventricles gets passed on to the aorta and the semilunar valves, the ventricles gets emptied and are known to return back to their original resting state; called as the state of ventricular repolarization.

An ECG is plotted using these different waves and complexes and they in turn give us an idea about the healthy functioning of the heart muscles and the disorders if any.

ECG statistics:

Normal P-R interval is reported to be: 0.12-0.2 seconds

Normally the duration of QRS complex is reported to be: lesser than 0.10 seconds

Normal Q-T interval is reported to be: 0.42 seconds

The S-T segment is known to begin at the end of the S wave and is also known to terminate towards the beginning of the dome shaped T wave.

Any deflection from these data and measurements would give an idea regarding the different diseases related to the working of the heart.

Conclusion:

A normal PR interval has a normal duration of: 0.12-0.2 seconds

ST segment is measured from: the end of the S wave and is also known to terminate towards the beginning of the dome shaped T wave