Heart disease

How the heart works

Your heart is a pump. It's a muscular organ about the size of your fist, situated slightly left of center in your chest. Your heart is divided into the right and the left side. The division prevents oxygen-rich blood from mixing with oxygen-poor blood. Oxygen-poor blood returns to the heart after circulating through your body.

• The right side of the heart, comprising the right atrium and ventricle, collects and pumps blood to the lungs through the pulmonary arteries.
• The lungs refresh the blood with a new supply of oxygen. The lungs also breathe out carbon dioxide, a waste product.
• Oxygen-rich blood then enters the left side of the heart, comprising the left atrium and ventricle.
• The left side of the heart pumps blood through the aorta to supply tissues throughout the body with oxygen and nutrients.

Heart valves

Four valves within your heart keep your blood moving the right way by opening only one way and only when they need to. To function properly, the valve must be formed properly, must open all the way and must close tightly so there's no leakage. The four valves are:

• Tricuspid
• Mitral
• Pulmonary
• Aortic

Heartbeats

A beating heart contracts and relaxes in a continuous cycle.

• During contraction (systole), your ventricles contract, forcing blood into the vessels to your lungs and body.
• During relaxation (diastole), the ventricles are filled with blood coming from the upper chambers (left and right atria).

Electrical system

Your heart's electrical wiring keeps it beating, which controls the continuous exchange of oxygen-rich blood with oxygen-poor blood. This exchange keeps you alive.

• Electrical impulses begin high in the right atrium and travel through specialized pathways to the ventricles, delivering the signal for the heart to pump.
• The conduction system keeps your heart beating in a coordinated and normal rhythm, which keeps blood circulating.

Various heart disease causes

The causes of heart disease vary by type of heart disease.

Causes of cardiovascular disease

While cardiovascular disease can refer to different heart or blood vessel problems, the term is often used to mean damage to your heart or blood vessels by atherosclerosis (ath-ur-o-skluh-ROE-sis), a buildup of fatty plaques in your arteries. Plaque buildup thickens and stiffens artery walls, which can inhibit blood flow through your arteries to your organs and tissues.

Atherosclerosis is also the most common cause of cardiovascular disease. It can be caused by correctable problems, such as an unhealthy diet, lack of exercise, being overweight and smoking.

Causes of heart arrhythmia

Common causes of abnormal heart rhythms (arrhythmias) or conditions that can lead to arrhythmias include:

• Heart defects you're born with (congenital heart defects)
• Coronary artery disease
• High blood pressure
• Diabetes
• Smoking
• Excessive use of alcohol or caffeine
• Drug abuse
• Stress
• Some over-the-counter medications, prescription medications, dietary supplements and herbal remedies
• Valvular heart disease

In a healthy person with a normal, healthy heart, it's unlikely for a fatal arrhythmia to develop without some outside trigger, such as an electrical shock or the use of illegal drugs. That's primarily because a healthy person's heart is free from any abnormal conditions that cause an arrhythmia, such as an area of scarred tissue.

However, in a heart that's diseased or deformed, the heart's electrical impulses may not properly start or travel through the heart, making arrhythmias more likely to develop.

Causes of congenital heart defects

Congenital heart defects usually develop while a baby is in the womb. Heart defects can develop as the heart develops, about a month after conception, changing the flow of blood in the heart. Some medical conditions, medications and genes may play a role in causing heart defects.

Heart defects can also develop in adults. As you age, your heart's structure can change, causing a heart defect.

Causes of cardiomyopathy

The cause of cardiomyopathy, a thickening or enlarging of the heart muscle, may depend on the type:

• Dilated cardiomyopathy. The cause of this most common type of cardiomyopathy often is unknown. It may be caused by reduced blood flow to the heart (ischemic heart disease) resulting from damage after a heart attack, infections, toxins and certain drugs. It may also be inherited from a parent. It usually enlarges (dilates) the left ventricle.
• Hypertrophic cardiomyopathy. This type, in which the heart muscle becomes abnormally thick, usually is inherited. It can also develop over time because of high blood pressure or aging.
• Restrictive cardiomyopathy. This least common type of cardiomyopathy, which causes the heart muscle to become rigid and less elastic, can occur for no known reason. Or it may be caused by diseases, such as connective tissue disorders, excessive iron buildup in your body (hemochromatosis), the buildup of abnormal proteins (amyloidosis) or by some cancer treatments.

Causes of heart infection

A heart infection, such as endocarditis, is caused when an irritant, such as a bacterium, virus or chemical, reaches your heart muscle. The most common causes of heart infection include:

• Bacteria
• Viruses
• Parasites

Causes of valvular heart disease

There are many causes of diseases of your heart valves. You may be born with valvular disease, or the valves may be damaged by conditions such as:

• Rheumatic fever
• Infections (infectious endocarditis)
• Connective tissue disorders

Risk factors

Risk factors for developing heart disease include:

• Age. Aging increases your risk of damaged and narrowed arteries and weakened or thickened heart muscle.
• Sex. Men are generally at greater risk of heart disease. However, women's risk increases after menopause.
• Family history. A family history of heart disease increases your risk of coronary artery disease, especially if a parent developed it at an early age (before age 55 for a male relative, such as your brother or father, and 65 for a female relative, such as your mother or sister).
• Smoking. Nicotine constricts your blood vessels, and carbon monoxide can damage their inner lining, making them more susceptible to atherosclerosis. Heart attacks are more common in smokers than in nonsmokers.
• Certain chemotherapy drugs and radiation therapy for cancer. Some chemotherapy drugs and radiation therapies may increase the risk of cardiovascular disease.
• Poor diet. A diet that's high in fat, salt, sugar and cholesterol can contribute to the development of heart disease.
• High blood pressure. Uncontrolled high blood pressure can result in hardening and thickening of your arteries, narrowing the vessels through which blood flows.
• High blood cholesterol levels. High levels of cholesterol in your blood can increase the risk of formation of plaques and atherosclerosis.
• Diabetes. Diabetes increases your risk of heart disease. Both conditions share similar risk factors, such as obesity and high blood pressure.
• Obesity. Excess weight typically worsens other risk factors.
• Physical inactivity. Lack of exercise also is associated with many forms of heart disease and some of its other risk factors, as well.
• Stress. Unrelieved stress may damage your arteries and worsen other risk factors for heart disease.
• Poor hygiene. Not regularly washing your hands and not establishing other habits that can help prevent viral or bacterial infections can put you at risk of heart infections, especially if you already have an underlying heart condition. Poor dental health also may contribute to heart disease.

Complications

Complications of heart disease include:

• Heart failure. One of the most common complications of heart disease, heart failure occurs when your heart can't pump enough blood to meet your body's needs. Heart failure can result from many forms of heart disease, including heart defects, cardiovascular disease, valvular heart disease, heart infections or cardiomyopathy.
• Heart attack. A blood clot blocking the blood flow through a blood vessel that feeds the heart causes a heart attack, possibly damaging or destroying a part of the heart muscle. Atherosclerosis can cause a heart attack.
• Stroke. The risk factors that lead to cardiovascular disease also can lead to an ischemic stroke, which happens when the arteries to your brain are narrowed or blocked so that too little blood reaches your brain. A stroke is a medical emergency — brain tissue begins to die within just a few minutes of a stroke.
• Aneurysm. A serious complication that can occur anywhere in your body, an aneurysm is a bulge in the wall of your artery. If an aneurysm bursts, you may face life-threatening internal bleeding.
• Peripheral artery disease. Atherosclerosis also can lead to peripheral artery disease. When you develop peripheral artery disease, your extremities — usually your legs — don't receive enough blood flow. This causes symptoms, most notably leg pain when walking (claudication).
• Sudden cardiac arrest. Sudden cardiac arrest is the sudden, unexpected loss of heart function, breathing and consciousness, often caused by an arrhythmia. Sudden cardiac arrest is a medical emergency. If not treated immediately, it is fatal, resulting in sudden cardiac death.

Prevention

Certain types of heart disease, such as heart defects, can't be prevented. However, you can help prevent many other types of heart disease by making the same lifestyle changes that can improve your heart disease, such as:

• Quit smoking
• Control other health conditions, such as high blood pressure, high cholesterol and diabetes
• Exercise at least 30 minutes a day on most days of the week
• Eat a diet that's low in salt and saturated fat
• Maintain a healthy weight
• Reduce and manage stress
• Practice good hygiene

The tests you'll need to diagnose your heart disease depend on what condition your doctor thinks you might have. No matter what type of heart disease you have, your doctor will likely perform a physical exam and ask about your personal and family medical history before doing any tests. Besides blood tests and a chest X-ray, tests to diagnose heart disease can include:

• Electrocardiogram (ECG). An ECG records these electrical signals and can help your doctor detect irregularities in your heart's rhythm and structure. You may have an ECG while you're at rest or while exercising (stress electrocardiogram).
• Holter monitoring. A Holter monitor is a portable device you wear to record a continuous ECG, usually for 24 to 72 hours. Holter monitoring is used to detect heart rhythm irregularities that aren't found during a regular ECG exam.
• Echocardiogram. This noninvasive exam, which includes an ultrasound of your chest, shows detailed images of your heart's structure and function.
• Stress test. This type of test involves raising your heart rate with exercise or medicine while performing heart tests and imaging to check how your heart responds.

• Cardiac catheterization. In this test, a short tube (sheath) is inserted into a vein or artery in your leg (groin) or arm. A hollow, flexible and longer tube (guide catheter) is then inserted into the sheath. Aided by X-ray images on a monitor, your doctor threads the guide catheter through that artery until it reaches your heart.

  The pressures in your heart chambers can be measured, and dye can be injected. The dye can be seen on an X-ray, which helps your doctor see the blood flow through your heart, blood vessels and valves to check for abnormalities.

• Cardiac computerized tomography (CT) scan. This test is often used to check for heart problems. In a cardiac CT scan, you lie on a table inside a doughnut-shaped machine. An X-ray tube inside the machine rotates around your body and collects images of your heart and chest.
• Cardiac magnetic resonance imaging (MRI). For this test, you lie on a table inside a long tube-like machine that produces a magnetic field. The magnetic field produces pictures to help your doctor evaluate your heart.

Heart disease treatments vary by condition. For instance, if you have a heart infection, you'll likely be given antibiotics. In general, treatment for heart disease usually includes:

• Lifestyle changes. These include eating a low-fat and low-sodium diet, getting at least 30 minutes of moderate exercise on most days of the week, quitting smoking, and limiting alcohol intake.
• Medications. If lifestyle changes alone aren't enough, your doctor may prescribe medications to control your heart disease. The type of medication will depend on the type of heart disease.
• Medical procedures or surgery. If medications aren't enough, it's possible your doctor will recommend specific procedures or surgery. The type of procedure will depend on the type of heart disease and the extent of the damage to your heart.

Lifestyle and home remedies

Heart disease can be improved — or even prevented — by making certain lifestyle changes. The following changes can help anyone who wants to improve heart health:

• Stop smoking. Smoking is a major risk factor for heart disease, especially atherosclerosis. Quitting is the best way to reduce your risk of heart disease and its complications.
• Control your blood pressure. Ask your doctor for a blood pressure measurement at least every two years. He or she may recommend more frequent measurements if your blood pressure is higher than normal or you have a history of heart disease. Optimal blood pressure is less than 120 systolic and 80 diastolic, as measured in millimeters of mercury (mm Hg).

• Check your cholesterol. Ask your doctor for a baseline cholesterol test when you're in your 20s and then at least every five years. You may need to start testing earlier if high cholesterol is in your family. If your test results aren't within desirable ranges, your doctor may recommend more frequent measurements.

  Most people should aim for an LDL level below 130 milligrams per deciliter (mg/dL), or 3.4 millimoles per liter (mmol/L). If you have other risk factors for heart disease, you should aim for an LDL below 100 mg/dL (2.6 mmol/L). If you're at very high risk of heart disease — if you've already had a heart attack or have diabetes, for example — aim for an even lower LDL level — below 70 mg/dL (1.8 mmol/L).

• Keep diabetes under control. If you have diabetes, tight blood sugar control can help reduce the risk of heart disease.

• Move. Exercise helps you achieve and maintain a healthy weight and control diabetes, elevated cholesterol and high blood pressure — all risk factors for heart disease. If you have a heart arrhythmia or heart defect, there may be some restrictions on the activities you can do, so talk to your doctor.

  With your doctor's OK, aim for 30 to 60 minutes of physical activity most days of the week.

• Eat healthy foods. A heart-healthy diet based on fruits, vegetables and whole grains — and low in saturated fat, cholesterol, sodium and added sugar — can help you control your weight, blood pressure and cholesterol.
• Maintain a healthy weight. Being overweight increases your risk of heart disease. A BMI of less than 25 and a waist circumference of 35 inches (88.9 centimeters) or less is the goal for preventing and treating heart disease.
• Manage stress. Reduce stress as much as possible. Practice techniques for managing stress, such as muscle relaxation and deep breathing.
• Deal with depression. Being depressed can increase your risk of heart disease significantly. Talk to your doctor if you feel hopeless or uninterested in your life.
• Practice good hygiene. Stay away from people with infectious diseases such as colds, get vaccinated against the flu, regularly wash your hands, and brush and floss your teeth regularly to keep yourself well.

Also, get regular medical checkups. Early detection and treatment can set the stage for a lifetime of better heart health.

Coping and support

You may feel frustrated, upset or overwhelmed upon learning you or your loved one has heart disease. Fortunately, there are ways to help cope with heart disease or improve your condition. These include:

• Cardiac rehabilitation. For people who have cardiovascular disease that's caused a heart attack or has required surgery to correct, cardiac rehabilitation is often recommended as a way to improve treatment and speed recovery. Cardiac rehabilitation involves levels of monitored exercise, nutritional counseling, emotional support, and support and education about lifestyle changes to reduce your risk of heart problems.
• Support groups. Turning to friends and family for support is essential, but if you need more help, talk to your doctor about joining a support group. You may find that talking about your concerns with others with similar difficulties can help.
• Continued medical checkups. If you have a recurring or chronic heart condition, regularly check in with your doctor to make sure you're properly managing your heart condition.