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VENTRICULAR FIBRILLATION
What is ventricular fibrillation?
Ventricular fibrillation is a condition in which disordered electrical activity causes the ventricles to contract in a rapid, unsynchronized, uncoordinated fashion. When this occurs, little or no blood is pumped from the heart.
AHA Scientific Position
Collapse and sudden death follows unless medical help is provided immediately. If treated in time, ventricular tachycardia and ventricular fibrillation can be converted into normal rhythm with electrical shock. Rapid heart beating can be controlled with medications by identifying or destroying the focus of rhythm disturbances. These days one effective way of correcting these life-threatening rhythms is by using an electronic device called an implantable cardioverter-defibrillator .
The information contained in this American Heart Association (AHA) Web site is not a substitute for medical advice or treatment, and the AHA recommends consultation with your doctor or health care professional.
What causes arrhythmias?Arrhythmia Web Site
Under some conditions almost all heart tissue can start a heartbeat. In other words, another part of the heart can become the pacemaker. An arrhythmia occurs
What are the symptoms and treatments for slow heartbeat?
These problems can produce a heartbeat that's either too slow or too fast. A heart rhythm that's too slow (bradycardia) can cause fatigue, dizziness, lightheadedness, fainting or near-fainting spells. These symptoms can be easily corrected by implanting an electronic pacemaker under the skin to speed up the heart rhythm
What are the symptoms and treatments for rapid heart beating?
Rapid heart beating, called tachycardia or tachyarrhythmia , can produce symptoms of palpitations, rapid heart action, dizziness, lightheadedness, fainting or near fainting if the heart beats too fast to circulate blood effectively. Heartbeats may be either regular or irregular in rhythm.
When rapid heart beating arises in the ventricles - called ventricular tachycardia - a life-threatening situation can arisse. The most serious cardiac rhythm disturbance is ventricular fibrillation , where the lower chambers quiver and the heart can't pump any blood. Collapse and sudden death follows unless medical help is provided immediately.
If treated in time, ventricular tachycardia and ventricular fibrillation can be converted into normal rhythm with electrical shock. Rapid heart beating can be controlled with medications by identifying or destroying the focus of rhythm disturbances. Today one effective way of correcting these life-threatening rhythms is by using an electronic device called an implantable cardioverter / defibrillator .
Blood clots can form during atrial fibrillation , a disorder found in close to 2 million Americans. In atrial fibrillation the two small upper chambers of the heart, the atria, quiver instead of beating effectively. Blood isn't pumped completely out of them when the heart beats, allowing the blood to pool and clot. If a piece of the blood clot in the atria becomes lodged in an artery in the brain, a stroke results. About 15 percent of strokes occur in people with atrial fibrillation.
How is atrial fibrillation treated?
Aspirin and warfarin are two medications currently used. They interfere with blood clotting, thus helping to reduce stroke risk in people with atrial fibrillation. A nationwide study reported in December 1996 found that less than 40 percent of patients with atrial fibrillation were taking warfarin. Anticoagulants are also given to people who have atrial fibrillation.
AHA Recommendation
Treating atrial fibrillation is an important way to help prevent stroke. For this reason, the American Heart Association recommends aggressive treatment of this heart arrhythmia .
What is atrial fibrillation?
Atrial fibrillation is a disorder found in about 2 million Americans. In it the two small upper chambers of the heart, the atria, quiver instead of beating effectively. Blood isn't pumped completely out of them when the heart beats, so it may pool and clot. If a piece of the blood clot in the atria becomes lodged in an artery in the brain, a stroke results. About 15 percent of strokes occur in people with atrial fibrillation.
How is atrial fibrillation treated?
Aspirin and warfarin are two medications currently used. They interfere with blood clotting, thus helping to reduce stroke risk in people with atrial fibrillation. A nationwide study reported in December 1996 found that less than 40 percent of patients with atrial fibrillation were taking warfarin. Anticoagulants are also given to people who have atrial fibrillation.
AHA Recommendation
Treating atrial fibrillation is an important way to help prevent stroke. For this reason, the American Heart Association recommends aggressive treatment of this heart arrhythmia .
HEART, HOW IT WORKS
The normal heart is a strong, muscular pump a little larger than a fist. It pumps blood continuously through the circulatory system. Each day the average heart "beats" (or expands and contracts) 100,000 times and pumps about 2,000 gallons of blood. In a 70-year lifetime, an average human heart beats more than 2.5 billion times.
The circulatory system is the network of elastic tubes that allows blood to flow throughout the body. It includes the heart, lungs, arteries , arterioles (small arteries), and capillaries (minute blood vessels). These blood vessels carry oxygen- and nutrient-rich blood to all parts of the body. The circulatory system also includes venules (small veins) and veins, the blood vessels that carry oxygen- and nutrient-depleted blood back to the heart and lungs. If all these vessels were laid end-to-end, they'd extend for about 60,000 miles - far enough to encircle the earth more than twice.
The circulating blood brings oxygen and nutrients to all the organs and tissues of the body, including the heart itself. It also picks up waste products from the body's cells. These waste products are removed as they're filtered through the kidneys, liver and lungs.
What is the structure of the heart?
The heart has four chambers through which blood is pumped. The upper two are the right and left atria ; the lower two, the right and left ventricles . Four valves open and close to let blood flow in only one direction when the heart contracts (beats).
The four heart valves are…
The mitral valve has two flaps; the others have three. Under normal conditions, the valves permit blood to flow in just one direction. Blood flow occurs only when there's a difference in pressure across the valves that causes them to open.
How does the heart pump blood?
The heart pumps blood to the lungs and to all the body's tissues by a highly organized sequence of contractions of its four chambers.
For the heart to work properly, the four chambers must beat in an organized manner. This is governed by an electrical impulse. A chamber of the heart contracts when an electrical impulse moves across it. Such a signal starts in a small bundle of highly specialized cells located in the right atrium - the sinoatrial node (SA node), also called the sinus node. A discharge from this natural "pacemaker" causes the heart to beat. This pacemaker generates electrical impulses at a given rate, but emotional reactions and hormonal factors can affect its rate of discharge. This lets the heart rate respond to varying demands.
TESTS TO DIAGNOSE HEART
DISEASE
Several tests are available to diagnose possible heart disease. The choice of which (and how many) tests to perform depends on factors such as the patient's risk factors, history of heart problems, current symptoms and the physician's interpretation of these factors.
In a person being evaluated for possible heart disease, the tests usually begin with the simplest and may progress to more complicated ones. Specific tests depend on the patient's particular problem(s) and the physician's assessment. Some of these tests are noninvasive - that is, they don't involve insertingg needles, instruments or fluids into the body. Those that do are called invasive tests. Most of these tests are described in detail in other sections of this guide.
What are some examples of noninvasive tests?
What are some examples of invasive tests?
Nuclear imaging (each requires a needle puncture in an arm vein)
Other imaging tests
Related AHA publication(s):
SILENT ISCHEMIA AND ISCHEMIC
HEART DISEASE
What is ischemia?
Ischemia is a usually temporary shortage of oxygen in a part of the body. It can occur when an artery bringing blood to that part, such as the heart, is narrowed by spasm or disease.
What is ischemic heart disease?
Ischemic heart disease includes heart attack and related heart problems caused by narrowed coronary arteries and thus less blood and oxygen reaching the heart. It's also called coronary artery disease and coronary heart disease.
What is silent ischemia?
As many as 3 to 4 million Americans may have ischemic episodes without knowing it. These people, who have ischemia without pain, have silent ischemia. They may have a heart attack with no prior warning. In addition, people with angina (chest pain) also may have undiagnosed episodes of silent ischemia. Various tests, such as an exercise test or a 24-hour portable monitor of the electrocardiogram (Holter monitor), are used to diagnose silent ischemia.
Related AHA publication(s):
ANGINA PECTORIS
What is angina pectoris?
Angina pectoris is the medical term for chest pain due to coronary heart disease. Angina is a symptom of a condition called myocardial ischemia . It occurs when the heart muscle (myocardium) doesn't get as much blood (hence as much oxygen) as it needs for a given level of work. Insufficient blood supply is called ischemia.
When does angina pectoris occur?
Angina often occurs when the heart needs more blood. For example, running to catch a bus could trigger an attack of angina while walking might not. Angina may happen during exercise, strong emotions or extreme temperatures. Some people, such as those with a coronary artery spasm, may have angina when they’re resting. (See below, unstable angina, Prinzmetal’s or variant angina pectoris.)
Angina is a sign that someone is at increased risk of heart attack, cardiac arrest and sudden cardiac death. See the related entries in this Guide, listed below. Also see "Risk Factors and Coronary Heart Disease," "Heart Attack Symptoms / Warning Signs" and "Angina Pectoris Treatments."
What is stable angina?
People with stable angina (or chronic stable angina) have episodes of chest discomfort that are usually predictable. They occur on exertion (such as running to catch a bus) or under mental or emotional stress. Normally the chest discomfort is relieved with rest and/or nitroglycerin.
People with episodes of chest discomfort should see their physician for an evaluation. The doctor will evaluate the person’s medical history and risk factors, conduct a physical exam, order a chest X-ray and take an electrocardiogram (ECG). Some people will also need an exercise ECG (stress test), an echocardiogram (ek"o-KAR'de-o-gram) or other tests to complete the diagnosis.
What is unstable angina?
In people with unstable angina, the chest pain is unexpected and usually occurs while at rest. The discomfort may be more severe and prolonged than typical angina or be the first time a person has angina. The most common cause is reduced blood flow to the heart muscle due to narrowing of the coronary arteries by atherosclerosis (ath"er-o-skleh-RO'sis). An artery may be abnormally constricted or partially blocked by a blood clot. Inflammation, infection and secondary causes can also lead to unstable angina. In a form of unstable angina called variant or Prinzmetal’s angina, the cause is coronary artery spasm.
Unstable angina is an acute coronary syndrome and should be treated as an emergency. People with new, worsening or persistent chest discomfort should be evaluated in a hospital emergency department or "chest pain unit" and monitored carefully. They’re at increased risk for
What is variant angina pectoris (Prinzmetal's angina)?
Variant angina pectoris is also called Prinzmetal’s angina. Unlike typical angina, it nearly always occurs when a person is at rest. It doesn’t follow physical exertion or emotional stress, either. Attacks can be very painful and usually occur between midnight and 8 a.m.
Variant angina is due to coronary artery spasm. About two-thirds of people with it have severe coronary atherosclerosis in at least one major vessel. The spasm usually occurs very close to the blockage.
Angina can also occur in people with valvular heart disease, hypertrophic cardiomyopathy (hi"per-TRO'fik kar"de-o-mi-OP'ah-the) or uncontrolled high blood pressure -- though these cases are rare.
HEART ATTACK SYMPTOMS / WARNING SIGNS
Some heart attacks are sudden and intense -- the "movie heart attack," where no one doubts what's happening. But most heart attacks start slowly, with mild pain or discomfort. Often the people affected aren't sure what's wrong and wait too long before getting help. Here are some of the signs that can mean a heart attack is happening.
If you or someone you're with has chest
discomfort, especially with one or more of the other signs, don't wait longer
than a few minutes (no more than 5) before calling for help. Call 9-1-1…Get to
a hospital right away.
Calling 9-1-1 is almost always the fastest
way to get lifesaving treatment. Emergency medical services (EMS) staff can
begin treatment when they arrive -- up to an hour sooner than if someone gets to
the hospital by car. The staff are also trained to revive someone whose heart
has stopped. You'll also get treated faster in the hospital if you come by
ambulance.
If you can't access the emergency medical services, have someone drive you to the hospital right away. If you're the one having symptoms, don't drive yourself, unless you have absolutely no other option.
STROKE SYMPTOMS / WARNING
SIGNS
IF YOU NOTICE ONE OR MORE OF THESE SIGNS, DON'T WAIT. STROKE IS A
MEDICAL EMERGENCY. CALL 9-1-1 OR YOUR EMERGENCY MEDICAL SERVICES. GET TO A
HOSPITAL RIGHT AWAY!
The American Stroke Association wants you to learn the warning signs of stroke:
Be prepared for an emergency.
Take action in an emergency.
What is a TIA or transient ischemic attack?
Any of the above signs may be temporary and last only a few minutes. This may be due to a "little stroke" or "mini-stroke" called a transient ischemic (TRANZ'e-ent is-KEM'ik) attack or T.I.A.
Most strokes aren't preceded by TIAs. However, of the people who've had one or more TIAs, more than a third will later have a stroke. In fact, a person who's had one or more TIAs is many times more likely to have a stroke than someone of the same age and sex who hasn't.
· Syncope
· Cardiopulmonary Resuscitation (CPR)
· Implantable Cardioverter-Defibrillator
· Premature Ventricular Contractions
