Decoding Heart Blocks: Understanding ECG Reports

ECG is a non-invasive examination in which electrodes are placed on the chest to observe the electrical impulses generated by the heart. The conductive activity regulates cardiac rhythm, and changes in the same can indicate various cardiovascular problems.

Doctors can analyse the condition of the heart by examining the graphical representation of the impulses in a standard ECG report. The key elements of an ECG report for evaluating the electrical activity are:

1. P Wave: It is the initial wave on an ECG that indicates atrial depolarisation (contraction). It reflects the electrical activity in the atria. A duration of around 0.06 to 0.12 seconds (60-120 ms) is considered normal.
2. QRS Complex: This represents ventricular depolarisation (contraction). It is the biggest and most noticeable wave on the ECG. It should have a duration of less than 0.12 seconds (120 ms).
3. PR Interval: This indicates the time it takes for the electrical impulse to move from the atria to the ventricles (duration between the start of the P wave and QRS complex).  It should be between 0.12 to 0.20 seconds (120-200 ms).
4. T Wave: This wave type represents ventricular repolarisation (relaxation). It reflects the ventricle restoration. They should be upright in most leads and not excessively peaked or inverted.
5. ST Segment: It is the line that connects the QRS complex to the T wave, denoting the early repolarisation of the ventricle.
6. Heart Rate: The number of heartbeats per minute is calculated from the R-R interval. The average heart rate for adults at rest ranges from 60 to 100 beats per minute (bpm). For children and athletes, it can be lower. 
7. Rhythm Analysis: Determines the consistency of the electrical activity of the heart.

The electrical system of the heart helps in significantly coordinating the contraction of the atria and ventricles. This allows blood to flow effectively through the heart. 

When the normal electrical signalling between the upper (atria) and lower (ventricles) cardiac chambers is disrupted. It leads to a heart block, also known as an atrioventricular (AV) block.

To understand heart block ECG findings, doctors look for specific ECG patterns and changes in the PR interval. Here's what to watch for in each type of heart block:

First-Degree Heart Block ECG:

A delay in the transmission of cardiac impulses from the atria to the ventricles characterises a first-degree heart block. Specifically, it is seen as a prolonged PR interval on the ECG.

1. The heart block ECG finding shows that PR intervals consistently increased.
2. The PR interval is significantly longer than the typical range.
3. Every atrial impulse is eventually transferred to the ventricles. However, there is a delay in transmission.

Second-Degree Heart Block ECG:

Partial conduction blocks between the atria and ventricles characterise second-degree heart blocks. There are two main subtypes of second-degree heart block: Mobitz I (Wenckebach) and Mobitz II.

In Mobitz I (Wenckebach):

1. Observe the PR interval gradually increasing with each beat until a heartbeat is dropped.
2. The PR interval stretches then gets shortened abruptly, resulting in a missed ventricular rhythm.
3. Multiple P waves with a single QRS complex resemble a "group beating" illustration.

In Mobitz II:

1. The PR interval remains steady. However, there are a few missing beats here and there.
2. It is distinguished by a constant PR interval and irregularly absent ventricular beats.

Third Degree Heart Block (Complete Heart Block ECG):

The most severe form of heart block is referred to as complete or third degree block. There is a complete dissociation between the atrial and ventricular electrical activity. 

1. The atria and ventricles beat independently, with no rhythmic link.
2. The electrocardiogram (ECG) may reveal two different and independent rhythms: atrial and ventricular.
3. The ventricular pace could be significantly slower than the atrial rate.

Note: First-degree heart blocks usually do not require treatment. However, third-degree heart blocks may need a pacemaker to regulate the cardiac rhythm (by improving atrioventricular coordination). 

After detecting a heart block through ECG, it's essential to consider lifestyle changes to ensure better heart health and manage the symptoms. Here are some general lifestyle changes to consider:

1. Regular Medical Follow-ups: Schedule consultations with an expert cardiologist to consistently monitor cardiac functioning. It also helps in preventing the progression of heart block.
2. Medication Adherence: If recommended, take medicines as directed to regulate heart rate and rhythm.
3. Healthy Diet: Consume a heart-healthy diet rich in fruits, vegetables, whole grains, proteins, and low-fat dairy products. Limit your salt intake to help control your blood pressure.
4. Weight Control: Individuals must maintain a healthy weight. This helps prevent heart strain and the development of severe health complexities.
5. Exercise Regularly: Engage in moderate-intensity physical activities regularly, as directed by your doctor. Overexertion and high-intensity workouts should be avoided.
6. Limit Caffeine and Alcohol: These should be reduced or eliminated as they can cause or aggravate arrhythmias.
7. Smoking Cessation: If you smoke, quitting is important. Such toxic substances get deposited on the atrial lining,  promoting plaque formation and cardiovascular constriction. Thus increasing the risk of heart disease and arrhythmias.

ECGs remain a cornerstone in the diagnosis and management of cardiac conditions, including heart blocks. To reduce the risk of heart blocks and related complications, regular check-ups and a heart-healthy lifestyle are necessary.

If you ever receive an ECG report or are concerned about your cardiac health, consult HexaHealth. Professionals at HexaHealth can explain the findings and recommend appropriate treatment or further tests. Get in touch now!

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