What is a Heart Attack?

Figure 1: Normal Coronary Artery
Cross-sectional Microscopic View


this is a layperson's term for a sudden blockage of a coronary artery. This blockage, which doctors call a coronary artery occlusion, may be fatal, but most patients survive it. Death can occur when the occlusion leads to an abnormal heartbeat (severe arrhythmia) or death of heart muscle (extensive myocardial infarction). In both of these situations, the heart can no longer pump blood adequately to supply the brain and other organs of the body. Almost all heart attacks occur in people who have coronary coronary atherosclerosis. So, this photo essay will review the structure (anatomy) of the normal coronary artery, the structural abnormalities (pathology) of the coronary artery in atherosclerosis, and the effect of these abnormalities on the heart.

What are the structures and functions of a normal coronary artery?

The coronary arteries carry blood to the heart to supply oxygen and necessary nutrients. As seen in Figure 1, the wall of a coronary artery has 3 distinct layers: the inner (intima), middle (media), and outer (adventitia) layers. The wall of the artery surrounds the lumen of the artery, which is the channel through which blood flows



Figure 1, smooth muscle is red, and connective (supporting) tissue is black (elastic) or blue (collagen).

The intima is best seen in the close-up view in Figure 1. It is composed of a layer of so-called endothelial cells that covers the artery's inner (lumenal) surface, connective (supporting) tissue (collagen and elastin), and a layer of compact elastic tissue called the internal elastic lamina (IEL). In the past, the intima was thought to be simply a passive layer whose major purpose was to serve as a barrier. Now, however, we know that the endothelial cells actually keep track of the pressure, flow, and "health" of the artery. Moreover, endothelial cells secrete chemicals that can adjust the function of the artery (e.g., vasodilator chemicals to widen and vasoconstrictors to narrow it) and growth of the artery wall (e.g., growth factors).

The media (M) is a layer made up primarily of smooth muscle cells (SMCs). The muscle can contract and relax to control the blood pressure and flow in the artery. Elastic tissue and collagen in the media, along with elastic tissue in the IEL, increase the elasticity and strength of the wall of the artery, as the artery contracts and relaxes. The adventitia is a layer of connective tissue and cells (e.g., SMCs) that produce this connective tissue. The adventitia contains potent factors, including one called tissue thromboplastin, that promote blood clotting. The clots are useful when the artery becomes injured because they can limit excessive bleeding from the injured artery.

What happens to the coronary artery in atherosclerosis?

In coronary atherosclerosis, injury to the intima of the artery leads to the formation of plaques, which are regions of thickening on the inner lining of the artery. How then do the plaques form? In response to the injury, the smooth muscle cells (SMCs) from the media and perhaps from the adventitia move (migrate) into the intima. In the intima, these SMCs reproduce themselves (divide) and make (synthesize) connective tissue. These processes of migration, division, and synthesis, which collectively are referred to as intimal proliferation (buildup), cause thickening of the intima. When cholesterol, other fats, and inflammatory cells, such as white blood cells, enter the proliferating, thickened intima, the result is an atherosclerotic plaque. Then, as these plaques grow, they accumulate scar (fibrous) tissue and abundant calcium. (Calcium is the hard material in our teeth and bones.) Hence, the plaques are often hard, which is why atherosclerosis is sometimes referred to as "hardening of the arteries."

Who gets coronary artery plaques and what happens to the plaques?

Most adults in industrialized nations have some plaques (atherosclerosis) on the inner (lumenal) surface of their coronary arteries. Autopsy studies of young soldiers who died in World War II, the KOrean War, and the Vietnam War showed that even young adults in their 20s usually have coronary arteries that exhibit localized (focal) thickening of the intima. This thickening is the beginning of intimal proliferation and plaque formation. The distribution, severity (amount of plaque), and rate of growth of the plaques in the coronary arteries vary greatly from person to person. Figure 2 shows a coronary artery with an uneven (asymmetric), stable atherosclerotic plaque. A stable plaque may grow slowly, but has an intact inner (lumenal) surface with no clot (thrombus) on this surface.

What causes a Heart Attack?

Rupture of a stable plaque in a coronary artery is the initial pathological event leading to a heart attack. When the rupture occurs, a clot suddenly forms in the lumen (channel) of the artery at the site of the rupture. Bleeding into the plaque often accompanies the rupture. The clot then blocks (occludes) the artery and thereby decreases the blood flow to the heart. This sequence of events in the coronary arteries is the basic problem in over 75% of people who suffer a heart attack. In some patients, more often women, there is just an erosion or ulceration of the plaque surface, rather than a full rupture that leads to clot formation in the coronary artery. Figure 3 shows an atherosclerotic plaque rupture and a clot in a coronary artery.


Figure 3: Rupture of Atherosclerotic Plaque in Coronary Artery
Cross-sectional Microscopic View


What happens to the heart muscle after a person survives a Heart Attack?

According to medical studies, 50% to 75% of people survive their first heart attack The others die during the heart attack because the decreased coronary blood flow causes a severe abnormal heart rhythm or extensive death of heart muscle. Figure 4 shows the heart of a patient who died 5 days after a heart attack. The photos show his myocardial infarction as it appears on the surface of the left ventricle and when the heart is sliced to view the muscle wall. About 90% of myocardial infarctions involve only the left ventricle (LV), which pumps oxygen-rich blood that comes from the lungs to the entire body. The other 10% also involve the right ventricle (RV), which pumps the blood to the lungs.


Figure 4: Myocardial Infarction Caused by Heart Attack
Views of Heart Surface and Slice Across Heart


If a person survives a heart attack, the heart muscle may return to normal or become a region of dead heart muscle (the myocardial infarction). The amount and health of the remaining heart muscle is the major determinant of the future quality of life and longevity for a patient after a heart attack. A heart attack can interrupt the normal electrical wiring of the heart, leading to abnormal heart rhythms. The heart attack can also weaken the pumping action of the heart causing shortness of breath due to heart failure. Each of these complications of a heart attack can occur at any time during the recovery period as a result of dead, dying, or scarring heart muscle.

Can a person have more than one Heart Attack?

Yes. Not uncommonly, people with coronary artery disease have more than one heart attack over the years. In fact, by looking at the heart tissue at exaamination of the tissue ie autopsy, pathologists can tell when myocardial infarctions occurred. Thus, very recent (acute, hours old) infarctions may appear as a pale brown region, infarctions days old (subacute) appear yellow, and healed (weeks to years old) infarctions appear as white scars in the heart muscle. Figure 5 shows three myocardial infarctions of different ages in the muscle of a left ventricle.

heartattack medication

Aspirin (known chemically as acetyl salicylic acid and often abbreviated as ASA) belongs to a class of medications called nonsteroidal anti-inflammatory drugs or NSAIDs. Aspirin and other NSAIDs, for example, ibruprofen (Motrin, Advil) and naproxin (Aleve), are widely used to treat fever, pain, and inflammatory conditions such as tendonitis. In addition to its effects on fever, pain, and, aspirin also has an important inhibitory effect on platelets in the blood. This antiplatelet effect is used to prevent the platelets from initiating the formation of blood clots inside arteries, particularly in individuals who have atherosclerosis or are otherwise prone to develop blood clots in their arteries.

what are antiplatelet agents

Antiplatelet agents are medications that block the formation of blood clots by preventing the clumping of platelets. There are three types of antiplatelet agents: aspirin, the thienopyridines, and the IIb/IIIa inhibitors. These agents differ in four ways: the way in which they prevent platelets from clumping, their potency (how strongly they prevent clumping), how rapidly they work, and their cost.

Asprin

Aspirin prevents blood from clotting by blocking the production of thromboxan A-2, a chemical that platelets produce that causes them to clump. Aspirin accomplishes this by inhibiting the enzym cyclo-oxygenase-1 that produces thromboxane A-2. While other NSAIDs also inhibit the COX-1 enzyme, aspirin is the preferred NSAID for use as an antiplatelet agent because its inhibition of the COX-1 enzyme lasts much longer than the other NSAIDs. Thus, aspirin's antiplatelet effect lasts for days while the other NSAIDs' antiplatelet effects last for only hours.

scenario: being laid off.

If it happens to you, and you had health insurance through your employer, what are your options now?

And what about the toll that losing your job can take on your physical and mental health?
Here are 10 practical tips about health insurance and health care, in case the pink slip comes.

1. Check with your spouse or partner.

If you're married or have a partner who has health insurance through their employer, look into getting added to their plan via special enrollment. That's often the most cost-effective option, and you don't have to wait until the open enrollment period -- but you need to do it within 30 days of losing eligibility for other coverage, according to background information posted on the Department of Labor's web site.Which can be found beside this post.

2. Consider COBRA.

COBRA (the Consolidated Omnibus Budget Reconciliation Act of 1986) allows you to keep the health insurance you had through your employer for up to 18 months.
COBRA will cost more than what got taken out of your former paycheck. Besides paying what you paid as an employee, you'll also pick up the tab that your employer covered, and you may also pay a 2% administrative fee.
"That can be cost prohibitive, but that is an option for people; they are able to keep that coverage during the time of transition," says Robert Zirkelbach, director of strategic communications for America's Health Insurance Plans, a trade group for health insurance companies.

Still, the U.S. Department of Labor's web site notes that "while COBRA rates may seem high, you will be paying group premium rates, which are usually lower than individual rates."
If your company closed or went bankrupt, COBRA won't be available; it's only an option if your company's health care plan is still around. And you have to enroll in COBRA; companies with at least 20 employees are usually required to offer COBRA coverage and to let employees know about that, according to the Department of Labor.

3. Look into private health insurance.

You can buy your own health insurance in the private health insurance market. Zirkelbach advises shopping around and taking a careful look at what you're buying, including:

Co-payments: a dollar amount you're expected to pay for doctor visits or prescriptions
Co-insurance:
a percentage of medical bills that you're responsible for
In-network and out-of-network doctors:

If you have a specific doctor in mind, ask the doctor's office or the health insurance company if that doctor is in the company's network of physicians.

Formularies: Find out if your medications are covered and what you would pay for them.

4. Got kids?

Find out about your state's children's health insurance program (SCHIP). If you meet certain financial standards, your children may be eligible for coverage through SCHIP. Contact your state health department to find out.

5. Know your rights about pre-existing conditions.

If you join a new group health insurance plan -- either through your spouse or partner's plan or in a new job -- you can't be denied coverage because of pre-existing medical conditions, but you may have a waiting period of up to a year in certain situations; the rules are posted on the Department of Labor's web site.

Private health insurance companies can deny your application for coverage based on pre-existing conditions.

5. Know your rights about pre-existing conditions.

If you join a new group health insurance plan -- either through your spouse or partner's plan or in a new job -- you can't be denied coverage because of pre-existing medical conditions, but you may have a waiting period of up to a year in certain situations; the rules are posted on the Department of Labor's web site.
Private health insurance companies can deny your application for coverage based on pre-existing conditions.

6. Can't get private health insurance?

Look into whether your state has a high-risk pool.

"That is for individuals who have medical conditions or have difficulty getting coverage -- several states have set up what are called high-risk pools that allow those individuals to purchase coverage," Zirkelbach tells WebMD.

7. Tell your doctor about the layoff

It's important for your doctor to know about the things in your life that are affecting you, notes Robert Schwartz, MD, professor and chairman of the department of family medicine and community health at the University of Miami Miller School of Medicine.
Schwartz tells WebMD that he has many patients dealing with layoffs, from manual laborers to corporate vice presidents, and others who are worried about losing their jobs.
"It's a very significant problem," says Schwartz. "Negative stress ... can be very detrimental to people's well-being."
Your doctor can also help you check on ways to lower your drug costs and other medical expenses.
People who have to do the firing also may be "under tremendous stress" and feel "guilt-ridden and conflicted about their own role" in layoffs, notes Schwartz.

8. Be aware of what stress may do to you.

"How people cope with this type of stress is very variable from one person to the other," says Schwartz.
"Some people start overeating, some people stop their healthy routines like exercise, some people have difficulty sleeping," he says, adding smoking and drinking to that list. "All of these affect our state of well-being."
In some cases, stress can lead to heart palpitations, depression, anxiety, gastrointestinal problems, headaches, or worsening of pre-existing conditions, notes Schwartz.

9. Get perspective, and get active.

"The first step is to help people understand ... that they're dealing with common problems," says Schwartz. "Then we talk about coping mechanisms."
Schwartz's list of helpful coping strategies includes exercise, taking a proactive approach to job seeking, and volunteering.

"I'm very much of the mind-set to get people out and doing things," Schwartz says. "People sometimes are so shocked by losing their job that they become unable to even start looking for another job."

10. Be optimistic.

"I always tell people that the glass is either half full or half empty, and there's not much to gain by being pessimistic,' says Schwartz.

"Although at the moment when you give that advice it's hard for people to hear, it's my impression that people who can find a way of being optimistic usually do better and eventually get another job. It helps them to walk into a job interview with a positive attitude," says Schwartz.