The Heart

The heart is made up of four chambers. The left atrium and the right atrium on top mainly collect the blood, and the left and right ventricles on the bottom pump the blood. Because the ventricles act as the main pumps for the heart, they are thicker and more muscular than the atria. The left and right sides of the heart are divided by a muscular wall called the septum. The right side of the heart receives oxygen-depleted blood and pumps it to the lungs via the pulmonary artery. The left ventricle pumps oxygen-rich blood out to the body via the aorta; the left ventricle is the main pumping chamber and has thick muscular walls.

Four valves regulate the flow of blood between the heart's chambers:

• The tricuspid valve regulates the flow of blood from the right atrium to the right ventricle.
• The bicuspid mitral valve regulates the flow of blood between the left atrium and the left ventricle. It is called the mitral valve because it resembles a bishop's pointy hat, or a miter.
• The pulmonary valve regulates blood flow between the right ventricle and the pulmonary artery (leading to the lungs).
• The aortic valve regulates blood flow from the left ventricle to the aorta.

The valves are pushed open by the force of the blood flow; once the pressure drops, they slam shut like trap doors ensuring the blood flows in one direction only. The lub-dub noise associated with the heartbeat is the sound of the valves opening and shutting.

Heart Attack

What is a heart attack?

A heart attack occurs when there is a severe blockage in an artery that carries oxygen-rich blood to the heart muscle. The blockage is usually caused by a blood clot that lodges in an artery that is already narrowed by the buildup of plaque (deposits of fat-like substances) along the wall of the artery. The sudden lack of blood flow to the heart muscle deprives the heart of oxygen and nutrients. If the blockage is not opened quickly, the heart muscle will suffer serious, permanent damage as areas of tissue die.

The medical term for a heart attack is acute myocardial infarction. Acute means sudden, myo refers to muscle, and cardia refers to the heart. The myocardium is the medical name for heart muscle. Infarct means that heart tissue has been destroyed or killed because it was deprived of oxygen for too long.

Sometimes a heart attack is caused by a coronary spasm—a coronary artery pinches itself off, restricting blood flow to the heart. This can happen in a normal artery but usually occurs in one that is already narrowed by the buildup of plaque along the artery wall. Women younger than 50 years of age who have a heart attack are more likely to have had a coronary spasm than men of this age or older men and women.

What is a silent heart attack?

A heart attack may occur without chest pain or any other symptoms; in this case, it is called a silent heart attack. It may be discovered days, weeks, or even months later during electrocardiogram ( ECG) testing. This kind of heart attack occurs more often in women than in men.  People who have a silent heart attack tend to be about 7 years older than those who have more typical heart attacks (74 vs. 67 years) and more often have diabetes or heart failure.  It's likely that people with diabetes are at a higher risk for silent heart attacks because diabetes interferes with pain perception and may make you less likely to notice heart attack symptoms.

Arrhythmias

what is an arrhythmia?

An arrhythmia is a change in the regular beat of the heart. The heart may seem to skip a beat, beat irregularly, or beat very fast or very slowly.
Having an arrhythmia does not necessarily mean that a person has heart disease. Many arrhythmias occur in people who do not have underlying heart disease.

What causes arrhythmias?

Many times, there is no recognizable cause of an arrhythmia. Heart disease can cause arrhythmias. Other causes include: stress, caffeine, tobacco, alcohol, diet pills, and cough and cold medicines.

Are arrhythmias serious?

Most arrhythmias are harmless and do not require extensive exams or special treatments. When an arrhythmia is associated with heart disease, it is heart disease—not the arrhythmia—that poses the greatest risk to the patient.
In a small number of people with serious symptoms, arrhythmias themselves are dangerous. These arrhythmias require medical treatment to keep the heartbeat regular. For example, a few people have a very slow heartbeat ( bradycardia), causing them to feel lightheaded or faint. If left untreated, the heart may stop beating altogether.

How common are arrhythmias?

Arrhythmias are common in middle-aged adults. More than 2 million Americans are living with Atrial Fibrillation, just one type of arrhythmia, and over 800,000 people are admitted to the hospital each year for heart rhythm disorders. As people get older, they are more likely to experience an arrhythmia.

What are the symptoms of an arrhythmia?

Most people have felt their heart beat very fast, experienced a fluttering in their chest, or noticed that their heart skipped a beat at some stage. Almost everyone has also felt dizzy, faint, or out of breath or had chest pains at one time or another. One of the most common arrhythmias is sinus arrhythmia, the change in heart rate that can occur normally when we take a breath. These experiences may cause anxiety, but for the majority of people, they are completely harmless.
You should not panic if you experience a few flutters or your heart races occasionally. But if you have questions about your heart rhythm or symptoms, check with your doctor.