Your heart isn’t plugged into an outlet. And you don’t use a switch to turn it on. But just like a lamp, your heart runs on an electrical system.
Every time your heart beats, an electrical signal travels from the upper to the lower chambers. Along the way, the signal tells your heart to contract and pump blood.
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 Causes
Some people are born with heart block. In others, it develops later in life.
If you’re born with it, it’s 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. Your heart may not have developed correctly in the womb. Doctors often don’t know what causes these birth defects.
If you have heart block that you weren’t born with, doctors call it “acquired” heart block. It’s 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
If medicine is the cause, a dosage change or prescription switch could correct the problem. Some of the other medical issues may correct themselves.
Types of Heart Block
AV (Atrioventricular) Heart Blocks:
AV heart blocks occur when the electrical signals that control the heart’s rhythm are delayed or prevented from reaching the ventricles. There are three grades of AV block, with increasing severity of the block:
First-degree AV block: The electrical signal is delayed but still reaches the ventricles.
Second-degree AV block: The electrical signal is partially blocked, causing occasional missed beats.
Third-degree AV block: The electrical signal is completely blocked, and the atria and ventricles beat independently of each other.
Mobitz types 1 and 2 are subtypes of second-degree atrioventricular (AV) block, which is a type of heart block.
Mobitz type 1 (Wenckebach): In Mobitz type 1, the electrical signals that control the heartbeat become progressively longer until one beat is completely blocked. This type of heart block is also known as Wenckebach.
Mobitz type 2: In Mobitz type 2, some beats are completely blocked while others are not, resulting in an irregular heartbeat. Unlike Mobitz type 1, the blocked beats in Mobitz type 2 are not predictable and can occur randomly.
Bundle Branch Blocks:
Bundle branch blocks occur when there is a problem with the electrical pathways in the heart that transmit signals throughout the ventricles. There are two types of bundle branch blocks:
Right bundle branch block: Electrical signals are delayed in the right bundle branch.
Left bundle branch block: Electrical signals are delayed in the left bundle branch.
Tachybrady syndrome is a combination of a fast heart rate (tachycardia) and slow heart rate (bradycardia). It occurs when there is a problem with the electrical signals that regulate the heart’s rhythm, causing it to alternate between fast and slow beats. Tachybrady syndrome is often associated with heart block and can increase the risk of heart problems.
Degrees of Heart Block
Doctors group heart block into categories based on how severe it is.
First-degree. This is the mildest form of heart block. The heart’s electrical signal is slowed but still gets where it’s going. You may not notice or need treatment.
Second-degree. Some of the signals don’t get to the right places. This may mean your heart beats more slowly or drops beats. It can be asymptomatic or symptomatic.
Third-degree (also called complete). No electrical messages get through. The rate and rhythm of your heartbeat is very slow or it may even stop entirely. This type of heart block can be fatal.
Heart Block Symptoms
Your symptoms depend on the type of heart block you have. If you have first-degree, you may not have any at all.
Second-degree symptoms may include:
- Chest pain
- Shortness of breath
- The feeling that your heart skips a beat
Third-degree heart block needs immediate medical attention right away. Call 911 for any:
- Cardiac arrest
- New, severe tiredness
- Irregular heartbeat or new palpitations
Who’s at Risk?
Heart block can happen to anyone. It’s more common in older people because it’s often a result of other heart issues. Those with heart block also may have:
- High potassium levels
- Hyperthyroidism, or overactive thyroid
- Lyme disease
- Recent open-heart surgery
Heart Block Diagnosis
Your doctor will take these things factors into account:
- Current health
- Any medications you are taking
- Family history of heart issues
- Health history
- Tobacco, drug, and alcohol use
After a physical exam, your doctor will use an EKG, or electrocardiogram, to check your heart’s electrical activity. They may also ask you to wear a monitor, called a Holter, for anywhere from a day to a month to track the rhythm of your heart.
Heart Block Treatment
For second- and third-degree heart block, you may get a small device called a pacemaker in your chest. This is considered “minor” surgery and you’ll be sedated for it. Like a backup electrical system, it reminds the heart to beat at a normal rate if it slows or stops.
Life After Heart Block
Just like your heart, your pacemaker needs to be treated right to work well. There are some things you 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.
- It’s fine to be active once you have your doctor’s OK, but skip contact sports like football or ice hockey.
- Get your pacemaker checked regularly to make sure it’s working well.