It is based on recording the electrical activities that occur during the operation of the heart through electrodes placed in different parts of the body. The electrocardiogram mainly shows electrical events and does not provide information about mechanical events.


  • Rhythm and conduction disorders
  • Blood supply of the myocardium
  • Hypertrophy of the heart muscle
  • Diseases of the pericardium
  • Electrolyte disorders


• Depolarization of the atrium
• less than 0.08 sec
• less than 3 mm

• Depolarization of the ventricle
• less than 0.12 sec

• Ventricular repolarization

• The time between the onset of the P wave and the onset of the QRS complex.
• Depolarization of the atria + the total time required for the impulse to pass to the atrioventricular (AV) node, bundle of His, branches, and Purkinje fibers.
• Normal value for PR interval is 0.12-0.20 sec (3-5 small squares)

• It is the electrically silent period between depolarization and repolarization of the ventricles.
• In normal condition, it tends slightly upwards on the isoelectric line.

• It is the time from the beginning of the QRS to the end of the T wave.
•Indicates the time taken for ventricular depolarization and repolarization.
• <0.42 sec

If the depolarization wave travels towards a positive electrode, positive; diverges, a negative potential is recorded. Negative if the repolarization wave is approaching the positive electrode; If it is moving away from it, it creates a positive potential.

• ECG leads are created according to the position of the electrodes.
• Leads obtained by using one positive and one negative electrode are bipolar (standard)
• Leads obtained with a single positive electrode are unipolar

Bipolar Derivation

• Derivation                Negative electrode            Pozitive electrode
I                                          Right arm                                Left arm
II                                        Right arm                                 Left leg
III                                       Left arm                                    Left leg

Right Leg: Clay  electrode

Unipolar Leads

• It is named according to where the positive electrode is placed.

  • aVR (R: right) on the right arm
  • aVL (L: left) on the left arm
  • aVF (F: foot ) in left leg

•The letter a (augmented) is used in these three derivations.

Since the sum of the voltages at the corners of the Einthoven triangle is zero, the potential at the extremity where the active electrode is located is equal to the total potential of the other two extremities, but in opposite directions.

Rhythm Disorders

* DYSRHYTHMIA; deviations from the normal electrical rhythm of the heart are called
* ARRHYTHMIA is the absence of electrical activity of the heart.


• Diabetes
• Using alcohol
• Caffeine
• Drug use
• HT
• Hyperthyroidism
• Stress
• Cigaret
• HR
• Blood electrolysis imbalance
• Changes in heart muscles

Sinus Rhythms

• Normal sinus rhythm
• Sinus bradycardia
• Sinus tachycardia
• Sinus arrhythmia
• Sinus arrest


ECG features;
➢ Regular rhythm (or age-appropriate in children) at 60-100 beats/minute.
➢ A normal P wave precedes each QRS complex.
➢ Normal P wave axis: P waves I and II. should be upside down in leads and inverted in aVR.
➢ PR interval remains constant.
➢ QRS complexes are < 100 ms wide (unless there is a pre-existing interventricular conduction delay).


❖ Stimulations from the sinus node are below 60 per minute.
ECG features;
PR interval: Fixed within normal limits
• Rhythm: Regular
QRS complex: Normal duration
• Speed< 60 beats/min
T wave: Normal duration Normal
• P wave: Normally sized QRS wave after each P



❖Stimulations from the sinus node are more than 100 per minute.
❖ECG features;
• P-R Range: Normal
• Speed : 100-160/minute
• QRS: Normal
• Rhythm : regular
• P wave: normal in size and shape


❖The stimuli from the sinus node are irregular.
❖Irregularity is often caused by inspiration and expiration.
❖ ECG features:
• Speed: Usually normal
• P-R: Normal
• Rhythm: Irregular
• QRS: Normal
• P wave: normal in size and shape


• Occurs when the sinus node fails to initiate an impulse.
• There is no whole P-QRS-T sequence for one or more cardiac cycles.
• Distortion occurs in the P-P range.
• Pause occurs in the absence of the P-QRS-T sequence.


• Premature atrial contraction
• Atrial tachycardia
• Atrial flutter
• Atrial fibrillation


❖Caused by an ectopic atrial focus.
❖The QRS complex is accompanied by an early, abnormal P wave, followed by a pause.
❖ ECG characteristics:
• P wave: It is premature and differs from sinus Pdalgae
• Speed: Usually normal
* Rhythm: Irregular. It is because of the pause that follows PAK.
• P-R range : Normal
• QRS: Usually normal


❖Three or more consecutive atrial ectopic beats constitute atrial tachycardia.
❖ ECG characteristics:
• P-R range : Generally not measurable.
• Speed: 140/250 beats/min
* Rhythm: Regular
• QRS: Usually normal
• P wave: Abnormal



❖It originates from a fast regular atrial focus.
❖Atrial muscles cause this rapid stimulation with a saw-toothed atrial deflection called F waves.
ECG features:
• Rate: Atrial rate is 250/400 while ventricular rate is variable.
• Rhythm: Regular
• P wave: There are two, three, four, or more F waves before each QRS complex.
• P-R range: Does not need to be measured.
• ORS: Normal


❖Atrial fibrillation is the most common sustained arrhythmia.
❖A rapid, irregular, chaotic beat from an ectopic atrial focus
time occurs.
ECG features:
• Rate: Atrial rate 400 or more, ventricular rate cannot be measured.
• Rhythm: Irregular
• P wave: There are irregular fibrillation waves instead of P waves.
• P-R range: Not measurable.


• Idioventricular rhythm
• Accelerated ventricular rhythm
• Early ventricular beat
• Ventricular tachycardia
• Ventricular fibrillation
• Ventricular flutter


❖ If, for some reason, no warning comes out of the sinoatrial node and no warning comes to the ventricles due to the supraventricular area, electrical warning begins to be generated from the ventricles. The ECG rhythm that occurs in this case is called idioventricular rhythm (IVR).
❖ The rhythm is regular, the speed is usually between 20 – 40 dec
❖ There is no P wave in the idioventricular rhythm according to physiology. Since there is no P wave, the PR distance cannot be mentioned either.
❖ Because QRS complexes originate in the ventricles, they are longer than 0.12 seconds (Wide QRS).
❖ The rate of idioventricular rhythm is 40 beats/min.


❖ The QRS complexes are wide because the impulses originate from the ventricle.
❖ There are no P waves in front of QRSs because the stimuli leave the ventricle.
❖ The speed is around 40-100/minute.
❖ It is usually seen as a reperfusion arrhythmia.


❖ It originates from an irritable focus in one of the ventricles.
❖ECG features:
• P-R range: Not measurable.
•Speed: It is variable.
• QRS: Wide or notched.
• Rhythm: Irregular
•P wave: There is no P wave.


❖ It is due to rapid impulses from an ectopic ventricular focus.
The disease is usually triggered by an early ventricular stroke.
❖ ECG characteristics:
Speed : 140-220 beats/min
* Rhythm : Regular in general
• P wave: There is no associated P wave
• P-R december: Cannot be calculated; There is no P wave
• QRS: Wide


• Ventricular fibrillation (VF) is the most important cardiac arrest rhythm.
• The ventricles suddenly begin to contract at a rate of up to 500 beats/min.• Rapid and irregular electrical activity makes the ventricles unable to contract synchronously, leading to sudden loss of cardiac output.
• The heart is not an effective pump after this point.
• If advanced life support is not provided quickly, this rhythm is fatal without exception.
❖ ECG characteristics:
* Irregular deviations from the jumble of variable height.
• There is no identifiable P wave, QRS complex or T wave.
• At a speed of 150 to 500 beats per minute.
* The height decreases with time.


• Continuous sine wave.
• No identifiable P wave, QRS complex, or T wave.
• Rate usually > 200 bpm.


– Sinoatrial node
– Atrioventricular node
-Bundle of feelings(right and left)
-Purkinje fibers

The sinoatrial node is located on the posterior wall of the right atrium and is the center that initiates the first beat of the heart. The stimulus here reaches the Atrioventricular node, which again settles in the atrium. From there, it passes through the bundles of His to both ventricles and terminates in the Purkinje fibers.


•First degree AV block

•Second degree AV block Type I

•Second degree AV block Type 2

  • Third degree AV block

First Degree AV Block:

The electrical impulse originates from the SA node and is normally conducted to the AV node.
Once the stimulus reaches the AV junction, it is temporarily delayed before being delivered to the ventricles.
ECG features;
Speed : Normal (60-100/minute)
Rhythm: Regular
P wave: Normal sinus P waves
P-R interval : Over 0.2 seconds (more than 5 small squares)
QRS : Normal

Second Degree AV Block:

The impulses reach the AV node normally.
Impulses may be blocked sometimes or regularly with the more common type.
The P-R interval is fixed.
ECG features:
Speed: Usually slow
Rhythm: Usually regular, but can be irregular if the block occurs intermittently or if the transmission rate changes.
P wave: QRS does not follow every P wave.
P-R range: Invariant.
QRS: If the block is in the AV node, it is normal, if it is below the AV node, it is wide.

Third Degree AV Block:

No messages from the atria can pass to the ventricles.
There is no connection between any P waves and the QRS complex.
Atria work separately, ventricles work separately.
P-P distances and R-R distances are equal. However, no connection can be established between them.
The source of the QRS complex is below the AV node. In QRS complexes originating from the point close to the AV node, the duration of the QRS complex is normal, while the duration of the QRS complexes originating from below is longer.
The ventricular rate can vary between 20-60/min.
The rhythm is regular.
It is a very serious AV block.
In general, all patients are fitted with a permanent pacemaker.


Speed 60-100/min is usually normal.
The rhythm is regular.
P wave, PR interval is normal, QRS is wide.
It is the delay or blockage of the transmission in the right or left branch of the bundles of feeling.
Activation of the blocked side is provided by the other branch through the septum.
Wide QRS complexes are seen.

Right Branch Block:

The duration of QRS is longer than 0.12 seconds in complete blocks.
It is between 0.10 and 0.12 seconds in incomplete blocks.
Deep S waves are seen in leads D1, aVL(left arm), V5, V6.
The ST segment or T wave is directed against the R direction.
A second R wave is observed in V1 and often in lead V2.

Left Branch Block:

QRS duration is longer than 0.12 seconds.
Septal Q wave disappeared in leads V5 and V6.
Notching is seen in the QRS complex in leads V5, V6, D1, and aVL (left arm).
Wide R waves are seen in leads D1, D2, V5, V6.
Deep S waves are observed in leads V1, V2, V3.


The myocardium has no electrical activity.
ECG features:
There are no wave deflections.
A straight line is seen on the EKG.


The first way to diagnose acute MI is to look for ST segment elevation.

In its damage, ST elevation/depression is 1-2 mV.
Necrosis is represented by the pathological Q wave. Greater than ¼ of the R wave (Q > 1/4 R) Duration >= 0.03 – 0.04 sec in many leads

Acute Myocardial Infarction Localization:
Anterior: V1-V6
Anteroseptal: V1-V4 High Lateral: I, aVL inferior: II, III, aVF
Diffuse Anterior: I, aVL, V1-V6
Posterior: high R in V1-V3, ST depression, T negativity

What Are the Symptoms of Heart Rhythm Disorder?

Some of the patients with heart rhythm disorders are not aware that they are experiencing any discomfort. In such cases, arrhythmia is usually detected by means of a routine examination or electrocardiography taken for another purpose. We can list the most prominent symptoms of heart rhythm disorder that cause complaints in patients as follows:
1. Palpitations
2. Irregularity in heartbeat
3. The feeling of bird fluttering in the chest
4. Feeling of emptiness
5. Shortness of breath
6. Dizziness

Rhythm disturbances that cause a slowdown in the heart rate can be manifested by dizziness, fainting, dizziness, or shortness of breath. In particular, there are conditions such as a pause in the heart rhythm at a time when you are active, dizziness and fainting if it is for 3 seconds or more.
In addition, in cases where the heart rate rises excessively, conditions such as fainting and dizziness may occur. In particular, complaints such as dizziness or chest pain that accompany the feeling of palpitations indicate the severity of the condition.

What Are the Causes of Heart Rhythm Disturbance?

People who have previously had a heart condition are at risk of developing a heart rhythm disorder. As a result of these diseases, a problem in the working order of the heart may occur. Cardiac pathologies such as coronary artery disease, heart attack or failure, endocarditis, in which the internal tissues of the heart become inflamed, heart valve disorders and congenital heart diseases are considered a risk factor for the development of arrhythmia.

Apart from these diseases, age, gender and various lifestyle factors can also be effective in the development of heart rhythm disorder. Arrhythmias with a severe course usually occur in individuals over 60 years of age. Medications that are usually used by older people due to various cardiovascular problems can also cause the heart rhythm to be affected. The incidence of some types of arrhythmias varies between the sexes. As an example, atrial fibrillation is more likely to develop in men than in women.

Eating habits are another factor that can affect the heart rhythm. Consumption of beverages containing substances such as alcohol or various stimulant caffeine can change the way the heart works. In general, there may be a predisposition to the development of arrhythmia in people who use tobacco.
Apart from these reasons, various health problems can also trigger the development of a heart rhythm disorder:

• Diabetes
* Chronic lung diseases
• Pulmonary embolism (throwing a clot into the lung)
• Emphysema
• Asthma
• Sleep apnea
* Disorders of the thyroid gland
* Hypertension (high blood pressure)
* Imbalances in the levels of minerals such as calcium, potassium or magnesium

What Is Good For Heart Rhythm Disorder?

Avoiding stress, smoking, alcohol, caffeine and some drugs will be the best steps to take to relieve heart rhythm disorders. Apart from this, when there is a rhythm disorder that develops on the basis of heart disease, the heart disease causing arrhythmia should be treated.


In treatment, first of all, the cause must be eliminated. If the cause cannot be treated or if the existing rhythm conduction disorder is life-threatening or symptomatic, treatment is required. Here, first of all, it is recommended to take general measures suitable for the detected problem such as rest, calming, and some special maneuvers, and if these are not sufficient, drug therapy or interventional treatments (such as pacemaker / ablation / arrhythmia surgery) are recommended. Medication is not recommended for extra beats that are observed in patients without heart disease and do not cause any complaints in the patient.

There are recommendations that patients with rhythm disorders should pay attention to. These patients should not do heavy exercise. Fluid intake should be adequate and balanced. Very cold and very hot weather can trigger an arrhythmia attack. Excessive alcohol, smoking, drinking too much tea and coffee can trigger a rhythm disorder attack. Insomnia, intense physical fatigue, psychological stress can also trigger an attack.

Regular physical activity is an important way to live a healthy lifestyle that makes you feel better and reduce symptoms. Being active can also help prevent other heart diseases or strokes. Physical activity also helps improve their quality of life and increase their ability to exercise and participate in activities of daily living.
At least 150 minutes of moderate physical activity each week is recommended for adults. Also, strength training exercises can be included at least twice a week. Stretching exercises can be done.

• Climbing stairs
• Walk
• Light jogging
• Swimming
• Exercises such as cycling can be done.
• When it is first started, it can be started with 10-minute exercises three times a day and increased gradually.
• The exercise program should be applied under the supervision of a physiotherapist after being checked by your doctor.
• Exercise should be arranged at the highest level that can be beneficial for you, without adversely affecting your clinical condition. So it should be both safe and effective.
• Aerobic exercises involving large muscle groups are appropriate. Aerobic exercises are exercises such as walking, cycling, brisk walking and swimming.
• At the beginning of the exercises, there should be a warm-up period of 10-15 minutes. The actual exercise period should last 15–30 minutes at the heart rate that suits you.
• There should be a cooling, relaxation and recovery phase of 5-10 minutes. • Exercises should be done at least 3 times a week, preferably every day.
• Your exercise heart rate should be between 90 and 126 beats/minute. The safest is to choose the lower exercise heart rate. In the early period, it is more accurate to apply it under the control of a physiotherapist in a hospital setting.

Resistance exercise training: If you have experienced a recent event, do not do resistance exercise. After reaching a certain level with the aerobic exercise program, you should start resistance exercises. Resistance exercises increase muscle strength, improve the heart and circulatory system, and make you feel better. It should be done 2-3 times a week, in the form of 8-10 repetitive exercises.


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