Heart block is a problem that occurs with the heart's electrical system. This system controls the rate and rhythm of heartbeats. ("Rate" refers to the number of times your heart beats in a minute.)

With each heartbeat, an electrical signal spreads across the heart from the upper to the lower chambers. As it travels, the signal causes the heart to contract and pump blood. This process repeats with each new heartbeat.

Heart block occurs when the electrical signal is slowed or disrupted as it moves through the heart.

Overview

Heart block is a type of arrhythmia (ah-RITH-me-ah). An arrhythmia is any problem with the rate or rhythm of the heart.

You can be born with heart block or you can develop it. If you're born with it, it's called congenital (kon-JEN-i-tal) heart block. If it develops after birth, it's called acquired heart block.

Acquired heart block is more common. Damage to the heart muscle or to the heart's electrical system causes acquired heart block. Diseases, surgery, or medicines can cause this damage.

Congenital heart block may be found before or after a baby is born. If certain diseases occur during pregnancy, they may cause a baby to be born with heart block. Some congenital heart defects also may cause congenital heart block. Often, doctors don't know what causes these defects.

The three types of heart block are: first degree, second degree, and third degree. First degree is the least severe and third degree is the most severe. This is true for both congenital and acquired heart block.

Doctors use a test called an EKG (electrocardiogram) to help diagnose heart block. This test detects and records the heart's electrical activity. It records the data on a graph so the doctor can review it.

Outlook

The symptoms and severity of heart block depend on which type you have. First-degree heart block rarely causes severe symptoms.

Second-degree heart block may result in the heart skipping a beat or beats. This type of heart block also can make you feel dizzy or faint.

Third-degree heart block limits the heart's ability to pump blood to the rest of the body. This type of heart block may cause fatigue (tiredness), dizziness, and fainting. Third-degree heart block requires prompt treatment, because it can be fatal.

A medical device called a pacemaker is used to treat third-degree heart block and some cases of second-degree heart block. This device uses electrical pulses to make the heart beat at a normal rate.

Types of Heart Block

You can be born with heart block (congenital) or you can acquire it. Acquired heart block is more common.

First-Degree Heart Block

In first-degree heart block, the electrical signal is slowed as it moves through the heart. When this occurs between the atria and the ventricles, it appears as a slightly longer, flatter line between the P and the R waves on the EKG.

First-degree heart block rarely causes any symptoms. Well-trained athletes and young people are at higher risk for first-degree heart block caused by an overly active vagus nerve. Activity in this nerve slows the heart rate. Some medicines, such as digitalis, also may trigger first-degree heart block.

First-degree heart block usually doesn't require treatment.

Second-Degree Heart Block

In this type of heart block, electrical signals between the atria and ventricles are slowed to a large degree. Some signals can't reach the ventricles. On an EKG, the QRS wave doesn't follow each P wave as it normally would.

If the signal is blocked before it reaches the ventricles, they won't contract and pump blood to the lungs and the rest of the body.

Second-degree heart block is divided into two different types, Mobitz type I and Mobitz type II.

Mobitz Type I

In this type (also known as Wenckebach's block), the electrical signals are delayed more and more with each heartbeat, until the heart skips a beat. On the EKG, the delay is shown as a line (called the PR interval) between the P and QRS waves. The line gets longer and longer until the QRS wave doesn't follow the next P wave.

Sometimes people with Mobitz type I feel dizzy or have other symptoms. This type of second-degree heart block is less serious than Mobitz type II.

Mobitz Type II

In this type, some of the electrical signals also don't reach the ventricles. However, the pattern is less regular than it is in Mobitz type I. Some signals move between the atria and ventricles normally, while others are blocked. On an EKG, the QRS wave follows the P wave at a normal speed. Sometimes, though, the QRS wave is missing (when a signal is blocked).

Mobitz type II is less common than type I, but it's usually more severe. Some people with type II need medical devices called pacemakers to maintain their heart rates.

Third-Degree Heart Block

In this type of heart block, none of the electrical signals reach the ventricles. This type also is called complete heart block or complete AV block.

When complete heart block occurs, special areas in the ventricles may create electrical signals to cause the ventricles to contract. This natural backup system is slow and isn't coordinated with the contraction of the atria. On an EKG, the normal pattern is disrupted. The P waves occur at a faster rate than the QRS waves.

Complete heart block can be fatal. It can result in sudden cardiac arrest and death. This type of heart block needs emergency treatment. A temporary pacemaker may be used to keep the heart beating until you get a permanent pacemaker.

Causes

Heart block has a number of causes. You can be born with this disorder (congenital) or acquire it.

Congenital Heart Block

One form of congenital heart block occurs in the babies of women who have autoimmune diseases, such as lupus. People who have these diseases make proteins called antibodies.

In pregnant women, these antibodies can cross the placenta. (The placenta is the organ that attaches the umbilical cord to the mother's womb.) They can damage the baby's heart and lead to congenital heart block.

Congenital heart defects (problems with heart's structure) also may cause congenital heart block. Often, doctors don't know what causes these defects.

Acquired Heart Block

A number of factors, such as diseases, surgery, medicines, and other conditions, can cause acquired heart block.

The most common cause of acquired heart block is damage to the heart from a heart attack. Other diseases that can cause heart block include coronary artery disease, myocarditis (inflammation of the heart muscle), heart failure, rheumatic fever, and cardiomyopathy.

Other diseases may increase the risk for heart block. These include sarcoidosis and the degenerative muscle disorders, Lev's disease and Lenegre's disease.

Certain types of surgery also may damage the heart's electrical system and lead to heart block.

Exposure to toxic substances and taking certain medicines, including digitalis and beta blockers, also may cause heart block. Doctors closely watch people who are taking these medicines for signs of problems.

In some cases, atrioventricular (AV) heart block has been linked to genetic mutations (changes in the genes).

An overly active vagus nerve can cause first-degree heart block. Activity in this nerve slows the heart rate. Well-trained athletes and young people are at higher risk for first-degree heart block due to this cause.

In some cases, acquired heart block may go away if the factor causing it is treated or resolved. For example, heart block that occurs after a heart attack or surgery may go away after recovery.

Also, if a medicine is causing heart block, the condition may go away if the medicine is stopped or the dosage is lowered. However, you shouldn't change the way you take your medicines unless your doctor tells you to.

Signs and Symptoms

Signs and symptoms depend on the type of heart block you have. First-degree heart block rarely causes symptoms.

Symptoms of second- and third-degree heart block include:

Fainting
Feeling dizzy or lightheaded
Fatigue (tiredness)
Shortness of breath
Chest pain

These symptoms may point to other health problems as well. If these symptoms are new or severe, call 9–1–1 or go to the hospital emergency room. If you have milder symptoms, talk to your doctor right away to find out whether you need prompt treatment.

How Is Heart Block Diagnosed?

Heart block may be diagnosed as part of a routine doctor's visit or during an emergency situation (third-degree heart block is an emergency).

Your doctor will diagnose heart block based on your family and medical histories, a physical exam, and results from tests.

Specialists Involved

Your primary care doctor may be involved in diagnosing heart block. However, if you have the condition, you may need to see a heart specialist. Heart specialists include:

Cardiologists (doctors who treat adults with heart problems)
Pediatric cardiologists (doctors who treat babies and youths with heart problems)
Electrophysiologists (cardiologists or pediatric cardiologists who specialize in the heart's electrical system)

Family and Medical Histories

To find out your family and medical histories, your doctor may ask whether:

You have any signs or symptoms of heart block
You have any health problems, such as heart disease
Any of your family members have been diagnosed with heart block or other health problems
You're taking any medicines, including herbal remedies and prescription and over-the-counter medicines
You smoke or use alcohol and drugs

Your doctor also may ask about other health habits, such as how much physical activity you do.

Physical Exam

During the physical exam, your doctor will listen to your heart's rhythm. He or she will listen carefully for abnormal rhythms or heart murmurs (extra or unusual sounds heard during heartbeats).

Your doctor also may:

Check your pulse to find out how fast your heart is beating
Check for swelling in your legs or feet, which could be a sign of an enlarged heart or heart failure
Look for signs of other diseases that could be causing a problem with the heart's rate or rhythm (such as coronary artery disease)

Diagnostic Tests and Procedures

EKG (Electrocardiogram)

Doctors usually use a test called an EKG (electrocardiogram) to help diagnose heart block. This simple test detects and records the heart’s electrical activity. It shows how fast the heart is beating and its rhythm (steady or irregular). An EKG also records the strength and timing of electrical signals as they pass through each part of the heart.

The data is recorded on a graph. Different types of heart block have different patterns on the graph. (For more information, see “Types of Heart Block.”)

A standard EKG test only records the heart’s activity for a few seconds.

Holter and Event Monitors

To diagnose first- or second-degree heart block, your doctor may have you wear a Holter or event monitor.

Holter and event monitors are similar to EKGs, but they're portable devices. You can wear a Holter or event monitor while you do your normal daily activities. This allows the device to record your heart's electrical activity for a longer time than an EKG.

Electrophysiology Study

For some cases of heart block, doctors may do electrophysiology studies (EPS). During an EPS, a thin, flexible wire is passed through a vein in your groin (upper thigh) or arm to your heart. The wire records your heart's electrical signals.

Other Tests

To diagnose heart block, your doctor may need to do tests to rule out other types of arrhythmias (irregular heartbeats). For more information, see "How Are Arrhythmias Diagnosed?"

How Is Heart Block Treated?

Treatment depends on the type of heart block you have. First-degree heart block usually needs no treatment.

If you have second-degree heart block, you may need a pacemaker. A pacemaker is a small device that's placed under the skin of your chest or abdomen. This device uses electrical pulses to stimulate the heart to beat at a normal rate.

If you have third-degree heart block, you will need a pacemaker. In an emergency, a temporary pacemaker may be used until you can get a permanent one. Most people who have third-degree heart block need pacemakers for the rest of their lives.

Some people with third-degree congenital heart block don't need a pacemaker for many years. Others may need a pacemaker at a young age or during infancy.

In some cases, acquired heart block may go away if the factor causing it is treated or resolved. For example, heart block that occurs after a heart attack or surgery may go away.

Living With Heart Block

First-degree heart block may not cause any symptoms or require treatment. If you've been diagnosed with this condition, ask your doctor whether you need to take any special measures to control it. Your doctor can tell you whether you need ongoing care or whether you need to change the way you take certain medicines.

If you have second-degree heart block that doesn't require a pacemaker, talk to your doctor about keeping your heart healthy. Your doctor will tell you whether you need ongoing care for your condition.

Living With a Pacemaker

People who have third-degree heart block and some people who have second-degree heart block need pacemakers. If you have a pacemaker, you should take special care to avoid things that may interfere with it.

Avoid close or prolonged contact with electrical devices and devices that have strong magnetic fields. These objects can keep your pacemaker from working properly.

Let all of your doctors, dentists, and medical technicians know that you have a pacemaker. You also should notify airport screeners.

Certain medical procedures can disrupt pacemakers. These include MRI (magnetic resonance imaging), electrocauterization during surgery, and shock-wave lithotripsy to get rid of kidney stones.

Your doctor may need to check your pacemaker several times a year to make sure it's working properly. Some pacemakers must be checked in the doctor's office, but others can be checked over the phone.

Ask your doctor about what types of physical activity are safe for you. A pacemaker usually won't limit you from doing sports and physical activity. But you may need to avoid full-contact sports, such as football, that can damage the pacemaker.

Nursing Priorities

Decreased Cardiac Output

The heat fails to pump enough blood to meet the metabolic needs of the body. The blood flow that supplies the heart is also decreased thus decrease in cardiac output occurs, blood then is insufficient and making it difficult to circulate the blood to all parts of the body thus may cause altered heart rate and rhythm, weakness and paleness

Excess Fluid Volume

When blood flow through the renal artery is decreased, the baroreceptor reflex is stimulated and rennin is released into the bloodstream. Renin interacts with angiotensinogen to produce angiotensi I. When angiotensin I contacts ACE, it is converted to angiotensin II, a potent vasoconstrictor. Angiotensin II increases arterial vasoconstriction, promote release of norepinephrine from sympathetic nerve endings, and stimulates the adrenal medulla to secrete aldosterone, which enhances sodium and water absorption. Stimulation of the rennin-angiotensin system causes plasma volume to expand and preload to increase.

Acute Pain

In ischemic heart disease, atherosclerosis develops in the coronary arteries, causing them to become narrowed or blocked. When a coronary artery is blocked, blood flow to the area of the heart supplied by that artery is reduced. If the remaining blood flow is inadequate to meet the oxygen demands of the heart, the area may become ischemic and injured and myocardial infarction may result. Neural pain receptors are stimulated by local mechanical stress resulting from abnormal myocardial contraction.

Hyperthermia

Presence of microorganisms stimulates the release of pyrogen from the leukocytes resetting the body’s thermostat to febrile level and then there would be activation of the hypothalamus, which will result in increase in epinephrine and norepinephrine, vasoconstriction of cutaneous vessels. The heat will be produced as peripheral vasodilation results in skin flushing and skin is warm to touch

Ineffective Breathing Pattern

Ineffective Breathing Pattern occurs when there is presence of spasm and inflammation of the lung tissue and parenchyma , these results in inability of the pt to move air in and out of the lungs as needed to maintain adequate tissue oxygenation and perfusion.

Ineffective Tissue Perfusion

Due to decreased cardiac output, there is decreased preload and stroke volume thus there is decreased blood pumped out from the blood. Decrease in stroke volume decreases perfusion throughout the body.

Activity Intolerance

As heart failure becomes more severe, the heart is unable to pump the amount of blood required to meet all of the body’s needs. To compensate, blood is diverted away from less-crucial areas, including the arms and legs, to supply the heart and brain. As a result, people with heart failure often feel weak (especially in their arms and legs), tired and have difficulty performing ordinary activities such as walking, climbing stairs or carrying groceries

Ineffective Airway Clearance

Mucus is produced at all times by the membranes lining the air passages. When the membranes are irritated or inflamed, excess mucus is produced and it will retain in tracheobronchial tree. The inflammation and increased in secretions block the airways making it difficult for the person to maintain a patent airway. In order to expel excessive secretions, cough reflex will be stimulated. An increased in RR will also be expected as a compensatory mechanism of the body due to obstructed airways.

Impaired Gas Exchange

The exchange in oxygenation and carbon dioxide gases is impeded due to the obstruction caused by the accumulation of bronchial secretions in the alveoli. Oxygen cannot diffuse easily.

Fatigue

Heart failure is a physiologic state in which the heart cannot pump enough blood to meet the metabolic demands of the body. Since the patient has inadequate cardiac output, it can lead to hypoxic tissue and slowed removal of metabolic wastes, which in turn cause the patient to tire easily.

Key Points

Heart block is a problem that occurs with the heart's electrical system. This system controls the rate and rhythm of heartbeats.
With each heartbeat, an electrical signal spreads across the heart from the upper to the lower chambers. As it travels, the signal causes the heart to contract and pump blood. The process repeats with each new heartbeat.
Heart block occurs when the electrical signal is slowed or disrupted as it moves through the heart.
You can be born with heart block or you can develop it. If you're born with it, it's called congenital heart block. If it develops after birth, it's called acquired heart block. Acquired heart block is more common.
Doctors use a test called an EKG (electrocardiogram) to help diagnose heart block. This test detects and records the heart's electrical activity. An EKG records the strength and timing of electrical signals as they pass through each part of the heart. The data is recorded on a graph so your doctor can review it.
The three types of heart block are: first degree, second degree, and third degree. First degree is the least severe and third degree is the most severe. This is true for both congenital and acquired heart block. Third-degree heart block may be fatal and requires prompt treatment.
Heart block has a number of causes. Autoimmune diseases and congenital heart defects may cause congenital heart block. Diseases, surgery, medicines, and other conditions may cause acquired heart block.
In some cases, acquired heart block may go away if the factor causing it is treated or resolved. For example, heart block that occurs after a heart attack or surgery may go away with recovery.
Signs and symptoms depend on the type of heart block you have. First-degree heart block rarely causes symptoms. Symptoms of second- and third-degree heart block include fainting, feeling dizzy or lightheaded, fatigue (tiredness), shortness of breath, and chest pain.
Heart block may be diagnosed as part of a routine doctor's visit or during an emergency situation (third-degree heart block is an emergency). Your doctor will diagnose heart block based on your family and medical histories, a physical exam, and results from tests.
Treatment depends on the type of heart block you have. First-degree heart block usually needs no treatment. People who have third-degree heart block and some people who have second-degree heart block need pacemakers. A pacemaker is a small device that's placed under the skin of your chest or abdomen. This device uses electrical pulses to stimulate the heart to beat at a normal rate.
If you have heart block or symptoms of heart block, it's important to talk to your doctor. He or she can tell you whether you need treatment and whether you should have ongoing medical care for your condition. If you have severe symptoms, you should call 9–1–1 or go to the hospital right away.

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Heart Block and Nursing management