What is Electrocardiogram:
An electrocardiogram is a kind of test which looks at your heart beat, rhythm and electrical impulse of heart. They monitor electrical activities of the heart and show it as a graphical representation which is known as electrocardiograph. By monitoring they provide us information if the heat has enlarged due to hypertension i.e high blood pressure or any other kind of myocardial infarction. This test is carried out by a trained healthcare specialist at clinics and hospitals. This test mainly involves attaching a small number of small and sticky sensors i.e known as electrodes to your arms, legs and chest from where these electrodes monitor electrical signalling of the heart.
Why it is Performed:
An Electrocardiogram is often used alongside other tests to help diagnose and monitor conditions affecting the heart. It can detect so many abnormalities of missfunction happening inside our heart. Some of the abnormalities which are detected by electrocardiogram are listed below:
Abnormal heart rhythm (arrhythmias)
If there are any blocked or narrowed arteries in your heart (coronary artery disease) are causing chest pain or a heart attack.
To find weather you have had a previous heart attack or not.
To monitor if the medicines are causing any side-effects to our body system.
Different Types of Electrocardiogram:
There are mainly three different types of ECG is performed:
Resting ECG: when your body is in resting state.under this type machine examine your heart beat during resting condition.
Ambulatory ECG: This type of ECG is conducted for 24 hours. The heart’s electrical impulses are measured by a device called the Holter Monitor.
Cardiac stress test: This test is used to measure ECG when you are on an exercise bike.
Types of Electrocardiogram Waves Produced During Checkup:
1. The P-wave:
It represents the electrical excitation (or depolarisation) of the atria, which leads to the contraction of both the atria.
Features of P- wave:
P duration < 0.12 sec
P amplitude < 2.5 mm
Frontal plane P wave axis: 0° to +75°
May see notched P waves in frontal plane
2. The QRS Complex:
It represents the depolarisation of the ventricles, which initiates the ventricular contraction.
Features of QRS complex:
QRS duration ≤ 0.10 sec
QRS amplitude varies from lead to lead and also from person to person. Two determinants of QRS voltages are:
Size of the ventricular chambers (i.e., the larger the chamber, the larger the voltage)
nearness of chest electrodes to ventricular chamber (the closer, the larger the voltage)
3. T-wave:
It represents the return of the ventricles from excited to normal state (repolarisation) and the end of the T-wave marks the end of systole.
The normal peak of the T wave is usually in the same direction as the QRS wave except in the right precordial leads. In the normal ECG the T wave is always upright.
By counting the number of QRS complexes that occur in a given time period, a person can determine the heart beat rate of an individual.
How to Perform Electrocardiogram:
They have small sticky electrodes attached to the arms, chest, legs.
These electrodes are connected to the ECG machine with the help of wires that help in detecting the electrical impulses occurring at each heartbeat.
These electrodes can detect every minute form of changes happening in heart muscles and draw every depolarising pattern of heartbeat on a graph.
Feature of Normal Electrocardiogram :
Heart beat should be in between 60-90 beats per minute (bpm).
PR Interval: 0.12 - 0.20 sec
QRS Duration: 0.06 - 0.10 sec
QT Interval (QTc ≤ 0.40 sec)
Medical Use of ECG:
The main function of ECG is to obtain information regarding the heart impulse. There is a great medical use of this information regarding your health issues like:
chest pain
shortness of breath
Lightheadedness
Dizziness
fainting spells
It is also required prior to any type of heart surgery, including surgery for pacemaker placement.
Why is an Electrocardiogram Performed:
ECG is done to determine or detect:
Abnormal heart rhythm (arrhythmias)
If there are any blocked or narrowed arteries in your heart (coronary artery disease) are causing chest pain or a heart attack.
To find weather you have had a previous heart attack or not.
To monitor if the medicines are causing any side-effects to our body system.
MCQ Questions on ECG:
1. ECG (Electrocardiogram) Was Developed First By
(a) Wilhelm His
(b) Steward
(c) Hubert Mann
(d) Willem Einthoven
Answer: (d)
2. This is the Classic ECG Change in MI (Myocardial Infarction)
(a) ST-segment elevation
(b) T-wave inversion
(c) Development of an abnormal Q wave
(d) All of these
Answer: (d)
3. In Which of these Conditions can Widened QRS and Tall-tented T Waves be Observed
(a) Hyponatremia
(b) Hyperkalemia
(c) Hyperglycemia
(d) Hyperphosphatemia
Answer: (b)
4. A Particular ECG Change Observed in Hypokalemia is
(a) ST segment elevation
(b) U wave(a position deflection after the T wave)
(c) Tall peaked T waves
(d) Widening of the QRS complex and increased amplitude
Answer: (b)
5. ECG Report Must Consist of the Following Information
(a) Rhythm, cardiac axis
(b) Conduction intervals
(c) Description of the ST segments, QRS complexes, T-waves
(d) All of these
Answer: (d)
6. For the Normal Heartbeat, Depolarization Stimulus Originates in
(a) His-bundle areas
(b) Epicardium
(c) Sinoatrial (SA)node
(d) Atrioventricular (AV) node
Answer: (c)
7. The Characteristics – slurring of the Initial QRS Deflection, Shortened PR Interval, and Prolonged QRS Duration are of this Condition
(a) Atrial tachycardia
(b) Left bundle branch block
(c) WPW (Wolff-Parkinson-White) syndrome
(d) Myocardial ischemia
Answer: (c)
8. P Wave Indicates
(a) Depolarization of right ventricle
(b) Depolarization of left ventricle
(c) Depolarization of both atria
(d) Atrial to ventricular conduction time
Answer: (c)
9. Ventricular Muscle Depolarization is Indicated By
(a) PR interval
(b) P wave
(c) U wave
(d) The QRS complex
Answer: (d)
10. ECG Identified By the PR Interval Tends to Become Longer with Every Succeeding ECG Complex Until There is a P Wave Not Followed by a QRS is Observed in
(a) Third-Degree Atrioventricular Block
(B) Second-Degree Atrioventricular Block, Type II
(C) Second-Degree Atrioventricular Block, Type I
(D) First-Degree Atrioventricular Block, Type II
Answer: (c)
FAQs on Electrocardiogram
1. What is the Full Form of ECG?
Ans: ECG stands for electrocardiograph.
2. How Many Different Types of Wave are There in ECG?
Ans: There are mainly three types of ECG peak:
The P-wave represents the depolarisation of the atria, which leads to the contraction of both the atria.
The QRS complex represents the depolarisation of the ventricles, which leads to the ventricular contraction.
The T-wave represents the return of the ventricles from excited to normal state that is repolarisation and the end of the T-wave marks the end of systole.
3. How is ECG Helpful ?
ECG (electrocardiogram) measures or records the electrical activity of our heart at rest and also it provides information about our heart rate and rhythm.
It further shows if there is any enlargement of the heart due to high blood pressure (hypertension).
4. Why is ECG Done?
ECG is done because of following reasons:
To detect any heart related issues.
To detect whether you have had any heart attack.
To find out if any medicine is causing any side effect on our body.
To know if there are any blocked arteries.
5. Explain Different Types of ECG?
There are mainly three different types of ECG is performed:
Resting ECG: when your body is in resting state.under this type machine examine your heart beat during resting condition.
Ambulatory ECG: This type of ECG is conducted for 24 hours. The heart’s electrical impulses are measured by a device called the Holter Monitor.
Cardiac stress test: This test is used to measure ECG when you are on an exercise bike.
