ECG ABNORMALITIES-ECG EDUCATION-B

ECG ABNORMALITIES

Before we go into the subject we must observe some parameters in the ECG.

AXIS OF THE ECG

The axis of the ECG is the major direction of the overall electrical conductions of the heart.

This we can see in the next post in detail.

First of all we must know about the columns in the ECG.

There are 12 columns in your ECG chart. Ignore the first three columns namely 1) aVR- V1- V4; 2)aVL- V2- V5; 3)aVF- V3- V6.

Note the last column which is Sinus Rhythm or Lead II- column. 

In this column you can observe three things namely normal sinus rhythm, sinus bradycardia, and sinus tachycardia. Any of the last two if present then your ECG is abnormal.

Fig-1

1. Normal Sinus Rhythm:-(See Fig-1)

In this the heart rate is normal (60 to 100 bpm), all R-R intervals are equal in length.

The P- wave appear normal (not over 2.5 mm or 2.5 ss)in height, and (not more than 0.12 sec or 3ss) in width. The P-wave represents the two upper chambers (Atria) contraction (Atrial Depolarization)
The QRS complex which represents the contraction of the lower chambers (Ventricular Depolarization)

The P-R interval is the length at the beginning of the upslope of the P-wave to the beginning of the QRS complex and normally it must be 0.12 to 0.20 seconds or 3 to 5 ss.

The normal duration of the QRS complex must be between 0.08 to 0.1 sec or 2 to 2.5 ss.

The amplitude of the R-wave in the sinus rhythm-II column should not be more than 20mm or less than 4 LS.
The QT interval(From the beginning of the Q-wave to the apex of the T-wave should not be more than 2 large boxes or 0.4 sec.
The ST interval fits and overlaps over the isoelectric line and its length is not over 0.08 sec or 2ss.

2. Sinus Bradycardia:-(See Fig-1)
    This can be identified from the ECG by calculating the HR which is <50 BPM.
The RR intervals are elongated
If still the waves are regular then it may not be worried and it may be temporary conditions due to lack of body movements.

3. Sinus Tachycardia:-(See Fig-1)
    This can be identified by calculating the HR which is above 130 BPM. Again if the waves are regular then this too not to be worried as it may be due to over activities such as sports, exercises or work overloads

PATHOLOGICAL OR ABNORMAL ECG 

Fig-2

1.Atrial Fibrillation(See Fig-2)

Examine the P-wave and the PR interval

In atrial fibrillation the P wave is almost absent or invisible and the QRS complexes are irregular as shown in the diagram above. (Fig-2)
Clinical Symptoms of A-fib:-
1.Palpitations with feelings of difficulties with racing flip-flap speed of the heartbeat.
2.Tiredness and weakness
3.Headache
4.Breath short
5.Chest tightness and pain
Atrial fibrillation also occurs if there is Sinoatrial Exit Block means the conduction is blocked and cannot exit out of SA node. A prolonged SA node exit block (III degree block) can cause cardiac arrest.
Some times or infrequently if there is a negative U-shape deflection that immediately follows the T-wave and if it is prominent then it means there is suspected hypokalemia (low potassium), or hypercalcemia(high calcium) or hyperthyroidism.
2. Atrial Flutter:-(See Fig-2)
In Atrial flutter the ECG shows many P-waves as in the diagram.
In atrial flutter the atrium is stimulated irregularly by the SA node.
Clinical symptoms of A-Flutter:-
Very similar to A-fib with less severity.
3.AV CONDUCTION BLOCK
There are three degrees of AV conduction blocks.
The symptoms are as follows:-
1. The heart rate slows down
2. Some times it may not be worried but many times it may be fatal.
3. In the ECG the P-R intervals are elongated to such a limit after which the P-wave and R-waves have no connections at all and the condition is the third-degree AV block.
4.Irregular Heartbeats
5.Syncope and dizziness
6.Chest pain.

Fig-3

4. Ventricular Tachycardia:-(See Fig-3)

Ventricular Tachycardia is the fast heart rhythm with ventricles contracting and relaxing very fast and equal to exceed 100 bpm. Because of ventricles' fast actions the atrial actions are masked and hence there are no visible P-waves. The heartbeat is so fast so that it has fewer chances to be filled with blood.
In VT randomly any two or three beats may be normal with clear P and T waves.
Symptoms of V.T:-
1.Neck tightening
2.Palpitations
3.Nausea and vomiting
4.Headache
6.Dizziness
5. Ventricular Fibrillation:-(See Fig-3)
Ventricular fibrillation is very similar to ventricular tachycardia but more serious than VT because in V.F the ventricles beat irregularly and faster than in VT and incoordinate to fill in and pump out the blood.VF if not treated immediately may lead to cardiac arrest and death.
Symptoms vary similar to VT.
6.Atrial Enlargements:-(See Fig-3)
From the ECG the appearance of the P-wave will indicate the presence of enlargements on either or both the atria. (see the diagram above)
The cone-shaped P-wave apex may indicate there is an enlargement in the right upper chamber (right atrium) 
Causes and symptoms:-
1. The tricuspid valve which is in between the right atrium and ventricle may be damaged.
2.Due to right ventricular failure.
3.Pulmonary hypertension -High pressure in the pulmonary artery.
4.Breathing difficulties
5.Palpitations
6.Arrhythmias
The M-shaped P-wave apex is the indicator of left atrial enlargement 
Causes and Symptoms:-
1.Due to the mitral valve regurgitation, stenosis, and damage
2.Left ventricle failure
3.High B.P
4.Atrial fibrillation
5.Heart failure
6.Fluid build-up and weight gain
7.Breathing difficulties
8.Palpitations.
7.Myocardial Infarction (Heart Attack)(Fig-3)
The ECG changes are as follows:-
1.T-waves are elevated (Hyperacute T-waves)
2.Elevated ST intervals
3.Followed by negative T-wave deflection
4. Finally negative large deflection of Q-wave occurs.
Ischemia develops due to a block of blood circulation and oxygen supply to a portion of the heart muscles. If this ischemia is mild and reversible the can recover its coronary blood supply.
But if the ischemia is severe and irreversible then heart cells will die which leads to MI.
Symptoms Of MI
1.severe, and crushing chest pain
2.Sweating due to sympathetic stimulation
3.Vomiting
4.Shock with decreased B.P, paleness, panic, weak pulse
5. Arrhythmias followed by ventricular fibrillation and collapse.

                                                   Continued...