What effects could a partial or complete obstruction of a coronary artery have on heart tissue?

Coronary artery disease (CAD) is the most common type of heart disease. Although it’s the top cause of death in the U.S., there is a lot you can do to prevent or treat it.

The trouble starts when a waxy substance called plaque builds up inside the arteries that supply blood to the heart muscle. It can take decades to block the blood flow, but it can eventually cause a heart attack or failure.

Starting as early as childhood, plaque -- a combination of cholesterol, fat, and other substances -- starts to stick to the walls lining your blood vessels.

It builds up over time. That makes arteries become harder and narrower, which doctors call “atherosclerosis.“

In some cases, plaque can break or rupture. As a result, blood cells called platelets will try to repair the artery, forming a blood clot.

Like gunk in a clogged drainpipe, this buildup prevents a free flow of blood through the arteries. Blood carries oxygen and nutrients to the heart. If you don’t get enough, it can lead to shortness of breath and chest pain (angina).

Without enough oxygen, the heart can become weaker. This can lead to an irregular heartbeat (arrhythmia). It can also cause heart failure, which means the heart can’t pump enough blood throughout the body to meet the body's needs.

If a plaque grows so large that it stops blood flow to the heart muscle, you could have a heart attack.  Most of the time, however, heart attacks happen from the smaller plaques that rupture.

In the early stages, you may not have any symptoms. But as the plaque continues to build up and curbs blood flow to the heart muscle, you may notice that you’re short of breath or fatigued, especially during exercise.

The most common symptom of CAD is angina, or chest pain. Some people mistake it for heartburn or indigestion.

With angina, your chest feels uncomfortable. You may also experience the feeling in the shoulders, arms, back, or jaw. You may feel:

  • Tightness
  • Discomfort
  • Pressure
  • Heaviness
  • Squeezing
  • Burning
  • Aching
  • Numbness
  • Fullness

If you have any of the following symptoms, call 911 immediately:

  • Chest pain, especially in the center or left side of the chest, which lasts for a few minutes, or goes away and comes back. It can feel like pressure, squeezing, fullness, or pain. Some people mistake it for indigestion or heartburn.
  • Discomfort in any part of your upper body. It could be in one or both arms, the shoulders, neck, jaw, or upper part of the stomach.
  • Shortness of breath with or without chest discomfort
  • Nausea or vomiting with lightheadedness, dizziness, or cold sweat

Women often have different heart attack symptoms than men. While the most common red flag is still chest pain, women are more likely to have other symptoms, such as shortness of breath, extreme fatigue, nausea, vomiting, and back or jaw pain.

Coronary artery disease (CAD) becomes more likely as you get older or if it runs in your family. But you can manage many other risk factors, including:

  • High cholesterol and triglycerides
  • High blood pressure
  • Smoking
  • Metabolic syndrome
  • Diabetes
  • Obesity and overweight
  • Lack of exercise
  • Stress, depression, and anger
  • Unhealthy diet
  • Too much alcohol
  • Sleep apnea

Your doctor will give you a checkup and talk with you about your symptoms, risks, and family history. You may also get tests such as:

  • Electrocardiogram (ECG or EKG), which measures the heart’s electrical activity and can assess heart damage
  • Stress test -- Usually, this involves walking on a treadmill or pedaling a stationary bike in a doctor’s office while your EKG, heart rate, and blood pressure are monitored. 
  • Chest X-ray
  • Blood tests to check on your levels of blood sugar, cholesterol, and triglycerides (a type of fat in the blood)
  • Cardiac catheterization in which a doctor guides a very thin, flexible tube (called a catheter) through a blood vessel in your arm or leg to reach your heart. The doctor injects dye through the catheter and then uses X-ray videos to see inside your heart.

Depending on your case, your plan may include:

Lifestyle changes: These time-tested methods sound familiar for a reason -- they work!

  • Favor foods that are low in trans fats, saturated fats, simple sugars, and sodium.
  • If you smoke, quit.
  • Be active every day, ideally for 30 minutes or more a day (first, ask your doctor if there are any limits on what you can do).
  • Work to stick to a healthy weight. 
  • Learn effective ways to manage your stress.

Medications: If these lifestyle changes aren’t enough, you may also need to take medicines to help your heart be healthier. They can include blood thinners (anticoagulants), aspirin and other anti-clotting medicines, ACE inhibitors, beta blockers, nitroglycerin, calcium channel blockers, certain immunosuppressants, statins, or PCSK9s. 

Angioplasty: This procedure can open blocked or narrowed arteries without opening up your chest. In angioplasty, a doctor threads a thin, flexible tube with a balloon through your blood vessels until it reaches the blocked artery. The doctor then inflates the balloon, which stretches the artery open so more blood can flow. In many cases, a tiny tube called a stent is also inserted to keep the blood vessel open. You’ll typically be in and out of the hospital in a day.  

Coronary artery bypass grafting is a type of surgery in which doctors use blood vessels from other parts of your body to make a detour around blockages in your coronary arteries. It’s a major operation and you’ll probably need to be in the hospital for at least 5 days.

Fortunately, there are a number of things you can do to reduce your chances of getting CAD.

Get wise to your risk. Speak to your doctor about getting your cholesterol, blood pressure, and blood sugar checked. If you have high cholesterol, high blood pressure, or diabetes, it’s important to manage those conditions.

Aim for a healthy weight. If you’re not sure what your target weight should be, ask your doctor. And if you have a lot of weight to lose, remember that even a modest amount of weight loss helps.

Avoid cigarette smoke. If you smoke, quit. Steer clear of secondhand smoke.

Limit your alcohol. One or two drinks may have some heart benefits, but too much is risky. Men should have no more than two alcoholic drinks and women should have no more than one per day. 

Eat smart. Eat whole foods and avoid trans fats, which can be found in many baked goods and deep-fried and processed foods. Get plenty of fiber-rich foods, such as fruits and veggies, whole grains, and beans. Limit salt and aim to have two servings of fatty fish, such as salmon, tuna, or mackerel, a week. They’re high in heart-healthy omega-3 fats.

Exercise regularly. You’ll want to get at least 30 minutes of moderate-intensity exercise (like hiking or going for a bike ride that makes your heart beat faster but not race) on 5 or more days a week. Speak with your doctor before you begin a new exercise routine.

Manage your stress level. Use strategies such as exercise, meditation, and other healthy activities that relax you.

Medically reviewed by University of IllinoisWritten by Yvette Brazier on January 18, 2018

  • What is it?
  • Types
  • Causes
  • Symptoms
  • Risk factors
  • Diagnosis
  • Treatment
  • Complications

Heart block, AV bundle, or bundle branch block affects the electrical system of the heart. It is different from coronary artery disease, which affects the heart’s blood vessels.

In heart block, the heart beats irregularly and more slowly than usual, potentially stopping for up to 20 seconds at a time.

This is due to a delay, obstruction, or disruption along the pathway that electrical impulses travel through to make the heart beat. It can result from injury or damage to the heart muscle or heart valves.

Heart block itself does not usually need direct treatment, but related underlying health conditions do.

A healthy human heart beats at about 60 to 100 times a minute. A heartbeat is one contraction of the heart muscles, which pushes blood around the body.

Normally, every heart muscle contraction is controlled by electrical signals that travel from the atria, or the upper chambers of the heart, to the ventricles, or the lower chambers.

A partial heart block happens when the electrical impulses are delayed or stopped, preventing the heart from beating regularly.

A complete heart block is when the electrical signals stop completely. The heartbeat will drop to about 40 times per minute.

Even changes to impulses that last only a fraction of a second can cause heart block.

Sometimes, a heart block makes it difficult for the heart to pump blood properly through the circulatory system, so the muscles and organs, including the brain, do not get enough oxygen to function properly.

Heart block typically causes lightheadedness, fainting, and palpitations. Depending on the severity of the heart block, this can be dangerous. For example, a third-degree heart block can worsen pre-existing conditions, such as heart failure. It can cause loss of consciousness and even sudden cardiac arrest. There can also be chest pain.

Coronary heart disease, on the other hand, occurs when a waxy substance, called plaque, builds up in the coronary arteries. It can cause chest pain, known as angina, or heart attack, also called myocardial infarction (MI).

There are three types of heart block.

First-degree heart block involves minor heartbeat disruptions, such as skipped beats. It is the least serious type of heart block, and it does not generally require treatment.

Second-degree heart block occurs when some electrical signals never reach the heart, causing dropped or skipped beats. The patient may feel dizzy, and they may need a pacemaker. The ventricle may not contract, as the atrial impulse did not reach the ventricles.

Third-degree or complete heart block is when electrical signals do not travel between the upper and lower chambers of the heart. It is more common in patients with heart disease. Without a pacemaker, there is a serious risk of heart attack.

In a healthy heart, electrical impulses that travel inside a heart muscle instruct it to contract, or beat. The impulses move along a pathway, from the upper heart chambers, through the atrioventricular (AV) node, to the lower chambers.

Along this pathway is a cluster of cardiac fibers. These are called the bundle of His, the “bundle branch block” or the “AV bundle.” This bundle divides into two branches, the right and left bundles. The bundles conduct the electrical impulses to the heart ventricles. Each ventricle has a branch.

Damage to one of the branch bundles can cause uncoordinated ventricular contractions, and an abnormal heart beat can result.

A blocked signal on the right side of the heart is not usually serious, but a block on the left side can indicate a higher risk of coronary artery disease, or some other heart problem.

If a person has a heart block, they may experience:

  • slow or irregular heartbeats, or palpitations
  • shortness of breath
  • lightheadedness and fainting
  • pain or discomfort in the chest
  • difficulty in doing exercise, due to the lack of blood being pumped around the body

People with a heart block may appear healthy, but they may have an underlying heart problem.

The most common cause of heart block is scarring of the heart tissue as people get older. Some people are born with heart block, but older people with a history of heart disease or smoking are most at risk.

The following conditions increase the risk:

  • cardiomyopathy
  • coronary thrombosis
  • myocarditis, or inflammation of the heart muscle
  • endocarditis, or inflammation of the heart valves
  • scar tissue in the heart, following surgery or a heart attack.

Acute, or sudden, heart block may also occur after a heart attack or a heart operation. It can also occur as a complication of Lyme disease.

A physician will discuss symptoms with the patient and listen to their heart. Depending on age and medical history, the doctor may suspect heart disease, and will refer the patient to a cardiologist, or a heart specialist.

Share on PinterestAn ECG tests for irregular heart beat.

There are a number of diagnostic tests for heart block.

An electrocardiogram (ECG) is the most common test. It records heart activity. Probes placed on the skin of the chest show the electric impulses through the heart as wave patterns.

Wave abnormalities may indicate heart block. An ECG can also reveal whether the left or right branch is affected.

Holter tape is a portable device which records all the patient’s heartbeats. The patient wears it under their clothing, and it records information about the electrical activity of the heart while the person carries out their normal activities for 1 to 2 days.

When symptoms occur, the patient presses a button. This creates a record of the heart rhythms that are present at that moment.

An echocardiogram is an ultrasound scan that allows the doctor to see the heart muscles and valves.

An electrophysiology test uses tiny electrical shocks to determine the cause of the abnormal rhythm, and where in the heart it is.

In a tilt-table test, the patient lies on a bed that changes position. This can provoke arrhythmia, or abnormal heartbeats.

There is no heart-block-specific treatment. Most people with bundle branch block have no symptoms, and they do not require treatment. However, any underlying causes, such as hypertension, will need treatment.

If a person with left bundle branch block has a heart attack, reperfusion therapy may be given to restore blood flow through blocked arteries.

This can be done by using an anti-clotting agent, such as streptokinase, to dissolve blood clots and increase blood flow to the heart. However, anti-clotting drugs increase the risk of bleeding.

An artificial pacemaker, a small, battery-operated device, may be implanted under the skin in a patient with a history of fainting. It is placed near the collarbone during a surgical procedure lasting 1 to 2 hours, under a local anesthetic.

Many pacemakers can be set to produce an electrical impulse only when needed. Some can sense if the heart stops beating, and produce an electrical impulse to restart it. The battery can last many years.

Pacemakers are not affected by cell phones, personal stereos, or household appliances, but a person with a pacemaker should not undergo a magnetic resonance imaging (MRI) scan.

People with a left side bundle branch block have a higher risk of complications than those with a right side block.

Possible complications include:

  • arrhythmia, or irregular heart beat
  • bradycardia, or low heart rate
  • insufficient contraction
  • cardiac arrest and circulatory failure
  • sudden cardiac death, which can be fatal within one hour of symptoms starting

Heart block is not always avoidable, but the risk of heart disease can be reduced by consuming a healthy diet, exercising regularly, minimizing alcohol consumption, and avoiding tobacco.

Last medically reviewed on January 18, 2018

  • Arrhythmia
  • Heart Disease
  • Cardiovascular / Cardiology

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