Second degree heart block type 2 is a serious but treatable condition that affects the flow of electrical signals through your heart. Treatment may involve a pacemaker to regulate heart function.
The steady flow of electrical impulses from the sinus node in the atria (your heart’s upper chambers) down to the ventricles (the lower chambers) keeps your heart beating strongly enough to pump blood throughout your body.
When those impulses don’t consistently reach the ventricles, the condition is called a heart block. Heart blocks are also called atrioventricular blocks.
Second degree heart block type 2 is not the most severe type of heart block, but it can cause noticeable, possibly serious symptoms. Your doctor may prescribe medications to help preserve your heart health. However, in many cases, an implantable pacemaker is necessary to restore a healthy heart rhythm.
This article takes a closer look at second degree heart block type 2, including the symptoms, causes, treatment, and outlook.
What are the three different types of heart blocks?
- First degree heart block: Impulses are slow from the atria but remain steady. Treatment is not always necessary.
- Second degree heart block: Impulses do not always reach the ventricles. Type 1 may not need treatment, but type 2 often requires a pacemaker.
- Third degree heart block (also known as complete heart block): Impulses stop reaching the ventricles altogether. A pacemaker is almost always necessary.
Second degree heart block type 2 is also called Mobitz type 2. It’s characterized by impulses from the sinus node that periodically don’t reach the ventricles. These impulses make your heart contract and pump blood to your lungs and the rest of your body.
Mobitz type 2 differs from the more common second degree heart block (known as Mobitz type 1), in which impulses from the sinus node get progressively slower until the heart skips a beat, starting the process all over again.
With second degree heart block type 2, you may have periods of normal, uninterrupted electrical flow in your heart, interspersed with brief episodes in which no impulses travel to the ventricles. Type 2 is the more dangerous kind of second degree heart block, as it can progress to third degree heart block if left untreated.
Mobitz type 1 second degree heart block sometimes causes no noticeable symptoms, but the symptoms of Mobitz type 2 are usually more obvious. They can include:
- dizziness
- fainting
- fatigue
- lightheadedness
Structural damage to the heart is usually at the root of second degree heart block type 2. The injury may result from a heart attack or an inadvertent complication of heart surgery. Other potential causes include:
- advancing age (the wear and tear on the heart over time can lead to electrical problems such as heart block and various arrhythmias)
- certain medications, including calcium channel blockers and digoxin
- hyperkalemia (unusually high levels of potassium in the bloodstream)
- scarring of the heart muscle (sometimes the result of an infection, though often the cause is unknown)
If you’ve had a heart attack or undergone heart surgery, you may be at a higher risk for second degree heart block type 2. A
A condition called left bundle branch block (LBBB) is also associated with a higher risk of second degree heart block type 2.
The heart has two pathways for impulses to travel from the atria to the ventricles: the right bundle branch and the left bundle branch. In LBBB, the impulses heading down the left bundle branch are much slower than those moving down the right bundle branch.
Because impulses are slow to reach the left ventricle, the impulses in the right bundle branch try to compensate and eventually reach the left ventricle to make it contract.
A proper diagnosis of second degree heart block type 2 involves a physical examination and a review of your medical history and current symptoms.
The most important diagnostic tool, however, is an electrocardiogram (ECG). During an ECG, a healthcare professional will place electrodes on your chest to detect any atypical electrical activity in your heart. It’s a painless, noninvasive test that is used to diagnose several types of heart rhythm disturbances.
Because your heart is not always in a state of second degree heart block type 2, you may need to wear a portable ECG device, such as a Holter monitor. You can wear it 24 hours a day to record any changes in your heart’s electrical patterns. An implantable loop monitor can do the same thing.
Treatment for Mobitz type 2 often begins with an assessment of possible reversible causes of second degree heart block. Stopping medications such as digoxin, beta-blockers, calcium channel blockers, and amiodarone may allow your heart to return to a normal rhythm.
However, the standard type 2 treatment is an implantable pacemaker. This is a small, battery-powered device that can be surgically implanted in your chest with wires or leads extending into your heart. The leads carry mild but effective electrical signals to keep your heart beating in a steady rhythm.
How to support healthy heart function
Living with second degree heart block type 2 means you should try to follow a heart-healthy lifestyle. The
- getting at least 150 minutes of moderate-intensity physical activity per week
- eating a healthy diet low in sodium and saturated fat and rich in fruits, vegetables, whole grains, and lean proteins
- quitting smoking, if you smoke, and avoiding exposure to secondhand smoke and air pollution as much as possible
You should also work with your doctor to keep your blood pressure, cholesterol, and blood glucose levels in healthy ranges.
If Mobitz type 2 causes you to faint, you may be at risk of a fall and fall-related injuries. The condition can sometimes lead to sudden cardiac arrest, which is the rapid and unexpected loss of heart function and consciousness. Cardiac arrest is often fatal if heart function is not restored quickly.
Mobitz type 2 can also
The long-term outlook for someone with Mobitz type 1 is generally promising, but the outlook for Mobitz type 2 is less clear.
The cause of the heart block and the severity of symptoms can both affect the outlook. For example, a 2021 study suggests that individuals younger than 50 who develop second degree heart block type 2 with no clear cause have a higher risk of heart failure and other serious complications.
If the underlying cause, such as a heart attack, is treated promptly and healthy blood flow is restored, type 2 heart block may be eliminated.
Otherwise, if you receive a pacemaker and make sure you have regular device checks and live a heart-healthy lifestyle, you should be able to live for a long time.
Second degree heart block type 2 is a serious but treatable condition affecting the consistent flow of electrical signals through your heart.
It’s important to remember that if you receive a pacemaker that restores a healthy heart rhythm, you still need to live a heart-healthy lifestyle. You’ll also need to work with your healthcare team to stay current with your annual blood work, device checks, and physical examinations and screenings.