Our heart is not plugged into an outlet. And we do not use a switch to turn it on. But just like a lamp, our heart runs on an electrical system. Every time our heart beats, an electrical signal travels from the upper to the lower chambers. Along the way, the signal tells our heart to contract and pump blood. Learn to know about howunblock the Cardiac Block.
When that signal is slowed down or kept from sending its message, it causes a condition called heart block. This affects the rate and rhythm of your heart, or the number of times it beats and the pattern of those beats.
Heart Block- An Overview
Heart block, also called AV block, is when the electrical signal that controls our heartbeat is partially or completely blocked. This makes our heart beat slowly or skip beats and our heart cannot pump blood effectively. Symptoms include dizziness, fainting, tiredness, and shortness of breath. Pacemaker implantation is a common treatment. Therefore, Cardiac block is a problem with our heart’s electrical system, which makes our heart beat and controls your heart rate and rhythm. The condition is also called atrioventricular (AV) block or a conduction disorder.
How The Heart Beats?
When the heart beats, the heart muscle contracts that is pulls inwards in order to pump blood around the body. The contractions are triggered by electrical impulses that are generated by a selection of specialised cells that are known as the sinoatrial node (SA node).
The SA node is often referred to as a natural pacemaker because, like artificial pacemakers, it generates a series of electrical impulses at regular intervals.
The impulse is then sent to another selection of cells that are known as the atrioventricular node (AV node). The AV node conducts the impulse into the two lower chambers of the heart (the ventricles).
A heart block occurs if the transmission of the impulse between the AV node and the ventricles is interrupted.
A Cardiac block does not mean that the heart stops beating altogether, because other ‘back-up’ systems can take over. However, it can result in an abnormally slow heartbeat or bradycardia, leading to the body’s organs and tissue becoming deprived of oxygen.
Types Of Heart Block
Cardiac block can be first, second or third degree, depending on the extent of electrical signal impairment.
First-degree heart block:
The electrical impulse still reaches the ventricles, but moves more slowly than normal through the AV node. The impulses are delayed. This is the mildest type of heart block.
Second-degree heart block is classified into two categories:
Type I and Type II. In second-degree heart block, the impulses are intermittently blocked.
Type I, also called Mobitz Type I or Wenckebach’s AV block:
This is a less serious form of second-degree heart block. The electrical signal gets slower and slower until your heart skips a beat.
Type II, also called Mobitz Type II:
While most of the electrical signals reach the ventricles every so often, some do not and your heartbeat becomes irregular and slower than normal.
Third-degree heart block:
The electrical signal from the atria to the ventricles is completely blocked. To make up for this, the ventricle usually starts to beat on its own acting as a substitute pacemaker but the heartbeat is slower and often irregular and not reliable. Third-degree block seriously affects the heart’s ability to pump blood out to our body.
Symptoms Of Heart Block
Symptoms of heart block vary depending on the type of block.
First-degree heart block:
May not have any symptoms.
May be found during a routine electrocardiogram (ECG) although heart rate and rhythm are usually normal.
First-degree block is common in athletes, teenagers, young adults, and those with a highly active vagus nerve.
Second-degree heart block symptoms:
Fainting, feeling dizzy.
Shortness of breath.
Third-degree heart block symptoms:
Shortness of breath.
Symptoms of third-degree cardiac block are more intense due to the slow heart rate. If a person has severe symptoms, one must take medical attention.
Causes Of Heart Block
Some people are born with heart block. In others, it develops later in life.
If one is born with it, it is called congenital heart block. Causes include:
An autoimmune disease:
Diseases, such as lupus, can be passed by your mother in certain proteins through the umbilical cord.
A birth defect:
Our heart may not have developed correctly in the womb. Doctors often do not know what causes these birth defects.
If one has heart block that one was not born with, doctors call it “acquired” heart block. It is the most common type. Causes include:
- Certain types of surgery that affect the heart’s electrical system
- Changes in your genes
- Damage from a heart attack
- Heart issues like clogged arteries, inflammation of the heart muscle, and heart failure
- Muscle disorders or other diseases
- Some medicines can also cause heart blocks. If medicine is the cause, a dosage change or prescription switch could correct the problem. Some of the other medical issues may correct themselves.
How Is Heart Block Diagnosed?
The cardiologist will first review the patient’s medical history and family health history and ask questions about the overall health, diet and activity level and symptoms. The patient is also asked about any medications he is taking that is prescription or over-the-counter and whether the patient smokes or use illicit drugs.
During the physical exam, the cardiologist will listen to the patient’s heart and check the heart rate. The patient will also be checked for signs of heart failure, such as fluid build-up in the feet, ankles, and legs.
The cardiologist may refer the patient to an electrophysiologist. Electrophysiologists are physicians who specialize in the electrical activity of the heart. Tests the patient might undergo include:
An electrocardiogram (ECG) records the patient’s heart’s electrical activity – its heart rate and rhythm and the timing of electrical signals as they move through our heart. This test can help determine the severity of the heart block. One may need to wear a portable ambulatory monitor device, such as a Holter monitor or an event recorder, for 24 to 48 hours or longer to collect more information about the heart’s electrical activity. If one needs to use a monitor, one will get detailed information about how to use it.
An implantable loop recorder:
This is a very slender device that is injected under the skin of the patient’s chest and can monitor the heart rhythm for up to five years. This is implanted as an outpatient in just a few minutes and is useful for patients who have very infrequent but important episodes without a clear explanation of their origin.
An electrophysiology study:
An electrophysiology study involves inserting a long, thin tube called a catheter through a blood vessel and guiding it to our heart to measure and record electrical activity from inside your heart.
Can Heart Block Be Prevented?
Some cases of heart block may be congenital that is present at birth. But most heart block develops after birth. Some causes cannot be prevented. We also know that the risk of heart block increases with age and so does heart disease. Some causes of heart disease are preventable.
Steps one can take to keep one’s heart and body as healthy as possible include:
- Lead a heart-healthy lifestyle, which includes eating a heart healthy diet, exercising regularly, getting an adequate amount of sleep each night, reducing stress, limiting alcohol, and stopping smoking and use of illicit drugs.
- Talk to the healthcare provider about reviewing medications and other supplements one is taking to determine if any change the normal levels of potassium, calcium, and magnesium – substances in the body that play a role with the heart’s electrical system. The provider can change the medication to a different drug class if needed.
How Common Are Heart Blocks?
First degree and Mobitz type 1 heart blocks are uncommon but not rare. It is estimated that 0.5-2% of otherwise healthy adults have these types of heart blocks.
Mobitz type 2 heart block is rare in the general population, but it is more common in people with certain heart conditions. For example, it is estimated that 1 in 30 people with heart failure will develop Mobitz type 2 heart block.
Congenital third-degree heart blocks are rare, occurring in 1 in every 20,000 births.
Conversely, acquired third degree heart block is a common complication of heart disease, particularly in older people. It is estimated that 5-10% of people who are over 70 years of age, and have a history of heart disease, will develop a third-degree heart block.
Who Is At Risk For Heart Block?
If one is born with heart block, one has congenital heart block. Either a condition one’s mother had during her pregnancy, or heart problems one was born with, cause this condition. Many instances of heart block occur because of some other condition or event such as:
older people are prone to heart blockages. Adults age 65 and older are more likely than younger people to suffer from cardiovascular disease, which is problems with the heart, blood vessels, or both. Aging can cause changes in the heart and blood vessels that may increase a person’s risk of developing cardiovascular disease.
Heart attack or coronary artery disease
Cardiomyopathies are diseases that weaken the heart muscle can also result in wire damage. Any disease that can infiltrate the heart such as sarcoidosis and certain cancers or any disease that results in heart inflammation such as certain autoimmune disease or infections can result in heart block.
Atrioventricular block or AVB, a common complication of cardiac sarcoidosis (CS), is caused by inflammation of the conducting system of the heart. AVB is a sign of worse prognosis, and thus its early diagnosis and treatment are important.
In up to 1% of patients with Lyme disease, complete heart block can develop 10, 11. The average time from initial presentation to complete heart block is 2 weeks that is 2–24 days. The time for resolution of complete heart block, after treatment is initiated, is usually 6 days although it can vary from 1 day to 7 weeks 12.
High potassium levels:
High serum potassium levels are thought to impair the conduction in the Purkinje fibres and ventricles more than in the AV node, although complete atrioventricular block can occur. In this case temporary pacing and excretion of the excessive levels of the serum potassium were essential.
Though the most common cardiovascular effects of hyperthyroidism are sinus tachycardia, atrial fibrillation, and atrial or ventricular premature complexes, complete atrioventricular (AV) block can occur, but it remains a rare occurrence.
Certain hereditary neuromuscular diseases
Medicines that slow the heart rate:
some medicines can be used to slow down the heart rate, and improve blood flow through our body. Excessive of such drugs can be fatal.
Post open heart surgery
Life After Heart Block
Just like our heart, our pacemaker needs to be treated right to work well. There are some things one can do to get the most out of it:
- Know what kind of pacemaker you have.
- Let all your health care providers know about your pacemaker.
- Wear a medical bracelet or necklace, to inform others of your pacemaker in an emergency.
- Stay away from electrical devices with strong magnetic fields.
- Eat healthy diets. Add foods to your diet that are low in cholesterol and saturated fats. Eat more fruits and vegetables. Eat less red meat and more white meat and fish. Consume fewer high-fat dairy products. Cut down on salt and sugar. Avoid fried and processed foods.
- It is fine to be active once you have your doctor’s confirmation, but skip contact sports like football or ice hockey.
- Get your pacemaker checked regularly to make sure it is working well.
Heart block may resolve on its own, or it may be permanent and require treatment. There are three degrees of heart block. First-degree heart block is the mildest type and third-degree is the most severe. With appropriate use of pacemaker therapy, most patients with advanced heart block can lead a normal life. So, unblock the heart block with proper medical assistance and lead a healthy life.
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