TOP FACTS ABOUT CARDIAC ARRHYTHMIA

Cardiac arrhythmia refers to an irregular heartbeat or abnormal heart rhythm. The heart normally beats in a regular pattern, but in cases of arrhythmia, the heart may beat too fast, too slow, or in an irregular pattern. This can disrupt the normal flow of blood and oxygen to the body’s organs and tissues.

Arrhythmias can occur due to various factors, including:

1. Electrical system abnormalities: The heart’s electrical system coordinates the contractions of its chambers. Disruptions in this system can lead to arrhythmias. For example, atrial fibrillation is a common arrhythmia characterized by rapid, irregular electrical signals in the atria.
2. Structural heart problems: Heart conditions such as coronary artery disease, heart attack, heart failure, or congenital heart defects can affect the heart’s electrical system and lead to arrhythmias.
3. Imbalances in electrolytes: Electrolytes like potassium, sodium, calcium, and magnesium play a crucial role in maintaining the heart’s electrical activity. Abnormal levels of these electrolytes can trigger arrhythmias.
4. Medications and substances: Certain medications, illegal drugs, and excessive consumption of alcohol or caffeine can disrupt the heart’s electrical system and cause arrhythmias.
5. Other factors: Age, family history, underlying medical conditions (e.g., high blood pressure, diabetes), stress, and hormonal imbalances can also contribute to the development of arrhythmias.

 

Some common types of arrhythmias include:

1. Atrial fibrillation (AFib): This is the most common type, characterized by a rapid, irregular heartbeat originating from the atria.
2. Ventricular tachycardia (VT): It involves rapid, abnormal electrical signals originating from the ventricles. VT can be life-threatening if not promptly treated.
3. Supraventricular tachycardia (SVT): It refers to episodes of rapid heart rate originating from above the ventricles.
4. Bradycardia: This refers to a slower-than-normal heart rate, typically below 60 beats per minute.
5. Premature ventricular contractions (PVCs): These are extra, abnormal heartbeats that start in the ventricles.

 

Treatment options for cardiac arrhythmia depend on the type and severity of the condition. They may include:

1. Medications: Anti-arrhythmic drugs can help regulate the heart’s rhythm and prevent abnormal electrical signals.
2. Cardioversion: This procedure involves delivering a controlled electric shock to the heart to restore a normal rhythm.
3. Catheter ablation: It involves the use of radiofrequency energy or extreme cold to destroy or isolate the areas of the heart causing abnormal electrical signals.
4. Implantable devices: Devices like pacemakers and implantable cardioverter-defibrillators (ICDs) can help regulate heart rhythm and deliver electric shocks if life-threatening arrhythmias occur.
5. Lifestyle changes: Modifying factors such as diet, exercise, stress, and avoiding substances that trigger arrhythmias (e.g., caffeine, alcohol) can be beneficial.

It’s important to consult with a healthcare professional for an accurate diagnosis and appropriate treatment plan if you suspect you may have a cardiac arrhythmia.

 

Ectopic Foci & Re-entry

Ectopic foci of excitation refer to abnormal electrical activity that originates from sites other than the normal pacemaker cells in the heart. These ectopic foci can disrupt the normal electrical conduction and rhythm of the heart, leading to various arrhythmias. Here are some examples of ectopic foci:

1. Atrial Ectopic Foci: These are abnormal pacemaker cells located in the atria, which can generate electrical signals independently of the sinoatrial (SA) node, the heart’s natural pacemaker. Atrial ectopic foci can cause atrial premature contractions (APCs) or atrial tachycardias.
2. Junctional Ectopic Foci: Junctional tissue is a specialized area in the heart that can initiate electrical impulses in the absence of the SA node. When these foci become hyperactive, they can trigger premature ventricular contractions (PVCs) or junctional tachycardias.
3. Ventricular Ectopic Foci: These are abnormal pacemaker cells located in the ventricles. They can generate electrical impulses independently of the atria and can result in premature ventricular contractions (PVCs) or ventricular tachycardias (VTs).

 

 

Arrhythmia ECG Descriptions

Here are the descriptions and ECG appearances of different types of arrhythmias:

1) Atrial Fibrillation (AF):

• Description: AF is a common arrhythmia characterized by disorganized electrical activity in the atria, resulting in a rapid and irregular ventricular response.
• ECG Appearance: The ECG shows the absence of P waves and irregularly spaced, fibrillatory waves (known as f-waves) that replace the normal P waves. The ventricular rhythm is irregularly irregular.

 

2) Atrial Flutter:

• Description: Atrial flutter is a rapid and regular atrial rhythm caused by a re-entry circuit within the atria.
• ECG Appearance: The ECG typically shows “sawtooth” or “picket fence” waves called flutter waves (F waves) that are usually best seen in leads II, III, and aVF. The atrial rate is usually between 250 and 350 beats per minute, with a regular ventricular response.

 

3) Supraventricular Tachycardia (SVT):

• Description: SVT refers to a group of arrhythmias originating above the ventricles, including atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT).
• ECG Appearance: The ECG may show a narrow QRS complex tachycardia with a regular rhythm. P waves may not be clearly visible or may be buried within the QRS complex.

 

4) Ventricular Tachycardia (VT):

• Description: VT is a rapid heart rhythm originating in the ventricles.
• ECG Appearance: The ECG shows a wide QRS complex tachycardia with a regular or irregular rhythm. The QRS complex morphology in VT is typically different from the normal sinus rhythm, and it may show a left or right bundle branch block pattern.

 

5) Ventricular Fibrillation (VF):

• Description: VF is a life-threatening arrhythmia characterized by rapid and chaotic electrical activity in the ventricles.
• ECG Appearance: The ECG shows an irregular, rapid, and disorganized rhythm with no discernible P waves or QRS complexes. Instead, there are irregular, low-amplitude waveforms (fibrillation waves) representing ventricular muscle activity.

It’s important to note that these descriptions and ECG appearances are general guidelines, and individual cases may vary. Proper diagnosis and management of arrhythmias should be done by qualified healthcare professionals.

 

Heart Block Classification

Conduction block refers to the impairment or interruption of the electrical conduction system within the heart, leading to an abnormal delay or absence of electrical impulses. These conduction abnormalities can be classified into different types, including incomplete (first and second degree) and complete heart block. Let’s discuss each of these types:

1) First-Degree Heart Block: First-degree heart block is characterized by a delay in the conduction of electrical signals from the atria to the ventricles. In this type of block, every electrical impulse is conducted through the conduction system, but it takes longer than usual to reach the ventricles. As a result, there is a prolonged PR interval on an electrocardiogram (ECG). Typically, first-degree heart block does not cause any symptoms or require specific treatment, as it is often considered a benign condition. However, it may be associated with underlying heart diseases or medications.

 

2) Second-Degree Heart Block: Second-degree heart block is further divided into two subtypes: Type I (Mobitz I or Wenckebach) and Type II (Mobitz II). Both subtypes involve partial conduction block from the atria to the ventricles.

• Type I (Mobitz I or Wenckebach): In this type, there is a progressive lengthening of the PR interval until a complete block occurs, and a ventricular beat is skipped. This pattern is typically repetitive, with a repeating cycle of lengthening PR intervals followed by a blocked beat. Mobitz I block is usually benign and rarely progresses to higher-degree blocks.
• Type II (Mobitz II): Mobitz II block is characterized by intermittent blockage of electrical impulses without prior lengthening of the PR interval. It is considered more severe than Mobitz I, as it may progress to complete heart block. Mobitz II block is associated with a higher risk of symptoms and may require medical intervention or a pacemaker to maintain normal heart rhythm.

 

3) Complete Heart Block (Third-Degree Heart Block): Complete heart block is the most severe form of conduction block, where there is a complete absence of electrical conduction between the atria and ventricles. In this condition, the atria and ventricles beat independently of each other. As a result, the ventricles generate their own electrical impulses, usually at a slower rate, leading to a slower heart rate compared to the normal sinus rhythm. Complete heart block requires immediate medical attention, and a pacemaker is often necessary to restore the proper coordination between the atria and ventricles.

It’s important to note that conduction blocks can have various causes, including structural heart disease, medications, myocardial infarction, inflammation, or certain genetic conditions. The severity of symptoms and the need for treatment depend on the type of block and its impact on heart function. Consulting a healthcare professional for proper evaluation and management is crucial if any heart rhythm abnormalities are suspected.