Just One Day of Exercise Protects the Heart

 

 

By Gabe Mirkin MD, September 26, 2011

“JUST ONE DAY OF EXERCISE CAN PROTECT THE HEART AGAINST…(A HEART ATTACK)…. and this protection is upheld with months of exercise, making exercise one of the few sustainable preconditioning stimuli” (Journal of Applied Physiology, September 2011). Wow.

HEART ATTACKS OCCUR WHEN A PLAQUE SUDDENLY BREAKS OFF FROM THE WALLS OF AN ARTERY SUPPLYING BLOOD TO THE HEART. The plaque travels down the ever-narrowing artery until it completely blocks the flow of blood to a part of the heart’s muscle. The heart’s muscle must receive oxygen from the bloodstream all the time. When a part of the heart muscle is suddenly deprived of oxygen, it dies and you suffer a heart attack. The dying heart muscle usually causes severe pain, in the chest, back or left arm. Heart attacks are not caused by progressive narrowing of an artery.

LACK OF OXYGEN IS THE ULTIMATE CAUSE OF HEART MUSCLE DAMAGE. Anything that increases the ability of the heart muscle to survive oxygen deprivation or increases oxygen supply to the heart muscle helps to prevent heart attacks.

Exercise helps to prevent heart attacks, and the more intensely you exercise, the greater the protection. Researchers in Norway treated recovering heart attack victims with the same intense training methods used by competitive athletes (American Heart Journal, June 2009). They supervised them as they ran on a treadmill very fast for a few seconds, rested and then repeated their intense intervals. For example, some of the patients ran fast for 30 seconds every five minutes. The interval-training heart attack victims were able to use more oxygen maximally (VO2max) and had their heart rates return toward normal faster than other heart attack victims who did slower continuous training. This advantage persisted for 30 months after the patients completed their 12-week rehabilitation program.

INTENSE TRAINING IS NOT ACCEPTED AS A TREATMENT FOR HEART ATTACK VICTIMS, particularly those who have chest pain with exercise or excessive shortness of breath. Intense exercise can precipitate heart attacks in people with blocked arteries. The exercise sessions are usually supervised by trained technicians using electrocardiograms, at least in the beginning.

INTENSE EXERCISE DOES NOT DAMAGE HEALTHY HEARTS. All known tests for heart function show no damage from intense exercise. Post-exercise electrocardiograms and echocardiograms are normal, as are blood levels of heart-specific enzymes, creatine kinase and creatine kinase MB, and myoglobin (Medicine and Science in Sports and Exercise, October 2003).

A WORD OF CAUTION: Before you start a program of cycling, running, tennis or anything else, realize that exercising intensely is far more likely to cause injuries and can cause heart attacks in people with blocked arteries leading to their hearts. You may want to check with your doctor before you start. Then get in shape gradually by exercising at an easy pace three to six days a week for at least six weeks.

 

Atherosclerosis

Danger level: High

What is it?

Atherosclerosis (the word comes from Greek, where “athero” means gruel or paste and “sclerosis” means hardness) is a process in which the arteries get clogged, putting you at risk for heart attacks, strokes and loss of blood circulation to your legs, intestines or kidneys.

Who gets it?

Anyone can get atherosclerosis. But there are risk factors which can put you at a greater risk of getting it. Some of them you can take care of, but some of them are inherent and can’t be changed:

  1. Cigarette smoking and exposure to tobacco smoke
  2. High blood pressure
  3. High blood cholesterol – Cholesterol has different forms. One of those is LDL cholesterol (also known as “bad cholesterol”). When it’s high you’re at a greater risk of developing atherosclerosis. The other is HDL cholesterol – this one is known as the “good cholesterol”. When this one is low you’re at risk of developing atherosclerosis.
  4. Diabetes
  5. Family history of having a heart disease in an early age – If you have a parent or sibling who had disease in the arteries of the heart (as opposed to other heart diseases) at an early age, you might be at a greater risk. What’s an early age? It’s usually before age 55 if it’s a man and 65 if it’s a woman.
  6. Age – If you’re a man over 45 or a woman over 55 you are at a greater risk.
  7. Obesity
  8. Physical inactivity – If you spend most of the time sitting and not doing any exercise you are at a greater risk.
  9. An improper diet – If what you eat contains a lot of saturated fats, cholesterol and trans fats (you can see that on the nutrition data labels on the foods you eat) you’re at a greater risk.

What causes it?

Our arteries contain a few layers, as can be seen in this picture:

 

 

The artery and its layers. Drawing by Stijn Ghesquiere

The outer layer is called the endothelium. Each of the risk factors listed above can cause damage to the endothelium. Once the endothelium is damaged, cholesterol invades the area and starts accumulating there. The white blood cells in our blood enter those areas to digest the bad cholesterol so that it won’t accumulate. Over time, those cells and the cholesterol together (along with other debris) accumulate as a mass, which is called a plaque. This created a bump in the wall of the artery.

This bump grows over time, reducing the flow of blood through the artery.

The following video shows this process in action –

 

How does it feel?

Atherosclerosis itself isn’t “felt”. Your arteries can get blocked to a certain degree and you will not feel the process. That is, until something happens.

That thing, as mentioned above, can be a stroke, something in other organs, or (the reason for this article) blockage of the arteries in your heart. This can lead to one of two things:

  1. Angina pectoris
  2. Myocardial infarction (“heart attack”)

In the upcoming parts we’ll discuss these two.

How is it discovered?

We will talk about how you can get diagnosed in the upcoming parts.

How is it treated?

Usually, until something develops as a result of the artery’s blockage, the condition isn’t treated. It can, however, be prevented, which is the most important thing you can do about it. Read ahead for that.


The bottom line – How do I avoid it?

There are 6 steps to lower your chance of developing atherosclerosis:

  1. Avoid smoking – We featured an article before about the benefits and ways you can stop smoking.
  2. Monitor your blood pressure – If you don’t know your blood pressure, visit your doctor to find out. If you do have a high blood pressure, they can recommend ways to lower it.
  3. Eat foods low in cholesterol and saturated fats – This article from the American Heart Association can help you choose the right foods.
  4. Be physically active – You can find more information on how to start here. Getting regular exercise can raise your “good cholesterol”.
  5. Maintain a healthy weight – The best way to start is by calculating your BMI. Your BMI (or Body Mass Index) can tell you if you’re in a healthy weight range or not. You can calculate yours here. A BMI of 18.5-25 is considered normal. If you’re between 25-30 you’re considered overweight. Above 30 is considered obese.
  6. Have regular medical exams

Chest Pain or Angina Pectoris

 

 

Angina pectoris is the medical name for chest pain or discomfort due to a disease in the heart’s arteries.

Who gets it?

Atherosclerosis causes a narrowing of the heart’s blood vessels. If more than 50% of the artery gets blocked, angina pectoris may start.

What causes it?

Our heart is a muscle. Muscles in our body, like any other organ, need oxygen in order to function. They get that oxygen when our blood, which is rich in oxygen, reaches them.

When the arteries which supply the heart with blood (called coronary arteries) are narrowed, like in atherosclerosis, the heart doesn’t get enough blood. In medicine, an insufficient blood supply is called ischemia. This is why you may hear the term “ischemic heart disease”, for the condition caused by atherosclerosis.

When the heart doesn’t get enough blood it “shouts” at you by producing pain, as you’ll see in the “how does it feel” section.

 

Angina occurs when our arteries are narrowed enough by a plaque that not enough blood reaches the heart.

 

 

How does it feel?

Angina is manifested as chest pain. It’s usually felt under the breast bone (around the center of the chest) like a deep pain. It usually lasts less than 30 minutes, and can radiate to the neck, the jaw or the left arm. It can be accompanied by breathlessness, cold sweat and nausea or vomiting.

There are 2 types of angina:

  • 1. Stable angina – These occur when you exert yourself (such as when walking or running) or when you’re under mental or emotional stress. Normally the pain subsides when you rest or when you take a drug called nitroglycerin.
  • 2. Unstable angina – This occurs when the narrowing of the coronary arteries is more severe. In this stage, the pain occurs even when you rest, meaning you don’t even have to have your heart pumping stronger than usual for it to feel the lack of oxygen – it will feel it even when it pumps regularly. This is a dangerous situation which signals a possible upcoming heart attack.The pain here can last longer and be more painful than in stable angina.

How is it discovered?

There are a few things a doctor can do to diagnose angina –

  • 3. The typical story helps to point in the right direction. Also doing a physical exam will help.
  • 4. An ECG (electrocardiogram) is done – This is a graph showing the electrical activity of the heart. To have this graph drawn, electrodes are attached to your chest, which detect the heart’s activity. This isn’t painful at all. When the heart lacks oxygen, a pattern can be seen on the ECG which the doctor will recognize.

 

Example of an ECG graph.

 

  • 5. Stress testing – Like mentioned above, angina doesn’t occur all the time, and sometimes a person with angina will come to the doctor when they don’t have pain at the moment. This is why stress testing is done. In it you run on a treadmill (like in a gym), causing your heart to work harder. This will trigger the pain of angina and the ECG changes, if your arteries are narrow. (There are people who can’t exercise for whatever reason. For these people a drug is given which makes their heart work harder, causing the same effect).
  • 6. Coronary angiography – When there is a high suspicion that you are at risk for a heart attack, or when the other tests are positive, a coronary angiography (also called catheterization) may be done. In this exam, a small tube-like device called a catheter is inserted through large arteries in the body, and reaches the coronary arteries. There it injects a material which can be seen in real time under X-ray. This shows the coronary arteries, and will show if they are narrowed.

 

The heart’s arteries (coronary arteries) as seen in a coronary angiography. Photo by Bleiglass.

How is it treated?

There are a few things that can be done to treat this condition:

  • 7. Changing risk factors which are reversible – Such as quitting smoking, lowering blood pressure, changing the diet. (For a complete list of the risk factors, see part 1).
  • 8. Drugs – There are several drugs given in this condition –
    a. Antiplatelet drugs – As you will see in part 3, angina can be a step before a heart attack. Since platelets are involved in the development of heart attacks (again, you’ll see why in part 3), inhibiting their action can help prevent a heart attack from happening. An example of such a drug is aspirin.
    b. Beta-blockers – These are drugs that make the heart work less strenuously, lowering the chance that it will reach a point where it lacks oxygen.
    c. Nitroglycerin – This drug causes widening of blood vessels, causing more blood to reach the heart. It’s usually taken when needed – when there’s pain.
    d. Statins – These are drugs that take down the “bad cholesterol” (LDL cholesterol) in the blood.

There are also other drugs which can be used, but the ones above are the most common.

If the narrowing is severe or if the above treatment doesn’t help, procedures for opening the narrowing in the heart’s arteries are performed.

What happens after treatment?

When not treated, heart attacks are likely to develop in people with angina, putting you at risk for death. When treated, however, this condition can be followed, with the chances of having a heart attack being greatly reduced.

 

 

Every year, more than 1 million Americans have a heart attack – a sudden interruption in the heart’s blood supply. This happens when there is a blockage in the coronary arteries, the vessels that carry blood to the heart muscle. When blood flow is blocked, heart muscle can be damaged very quickly and die. Prompt emergency treatments have reduced the number of deaths from heart attacks in recent years.

 

 

This section deals with the real thing – the heart attack that can be caused by the plaques in the heart’s coronary arteries.

Danger level: High

What is it?

A heart attack (or myocardial infarction by its medical name) occurs when the blood supply to part of the heart is interrupted, causing the heart cells in that part to die.

Who gets it?

People in danger of having a heart attack are the same ones who have the risk factors for developing atherosclerosis

 

What causes it?

The plaque that builds up inside the artery can eventually burst, tear or rupture. When the plaque ruptures, the body recognizes this as damage to the artery. Remember what happens when you have a wound on your skin? Within a short time it clots, sealing down the wound so that blood won’t spill from it. The same thing happens here: The “wound” in the artery clots.

How does this clotting happen? Platelets are the cells in our blood responsible for clotting. They aggregate together, helping the clot form. The clot is called a thrombus.

You might think to yourself – “the body has done its job right. The wound in the artery is healed.”. But the clotting process here is actually what brings about the heart attack. The clot in the artery can lead to an occlusion of the blood flow inside the artery, causing blood to not pass in the artery anymore. This leads to blood not reaching where it should in the heart.

 

 

 

 

When blood doesn’t reach a part of the heart, that part doesn’t get oxygen. When this happens, the cells in that part start dying. When they finally die, they can’t grow back, and that part of the heart is lost and will not function anymore.

The time it takes for the cells to die is a few hours. If the condition is treated within that time frame, the heart can be saved.

This video shows the process visually –

 

 

 

 

How does it feel?

A heart attack feels like angina, but lasts more than 30 minutes and is not relieved by nitroglycerine or by rest. Here’s a reminder of the symptoms:

  1. Pain, pressure, discomfort or heaviness in the chest. It can radiate to the left arm, the neck or the jaw.
  2. Sweating, nausea, vomiting or dizziness may accompany the pain.
  3. Rapid or irregular heartbeats may be felt as well.

How is it discovered?

There are a few things that can be done when you reach the ER to see if you have a heart attack:

  1. ECG: You can read an explanation about that in part 2.
  2. Blood tests: When the cells in the heart start dying, certain materials (called enzymes) start leaking out from them and into the blood. These enzymes are called troponins. When their level in the blood is high, this hints to a heart attack.
  3. Coronary angiography – (see an explanation in part 2) can be used to visualize the arteries in the heart to see if they are blocked.

How is it treated?

Perfusion is a word that means blood coming into an organ. In a heart attack, blood is not reaching the heart muscle properly. In order to bring blood back into the heart, the artery needs to be re-opened. This process is called re-perfusion.

There are 3 ways to get the artery opened:

  1. Percutaneous coronary intervention (PCI) – This is a long and complicated name, but the procedure is simple to understand.  Angiography show your heart’s arteries?
  2. It can also be used to treat the arteries. The catheter which is inserted into the arteries is used to do one of two things. It can inflate a balloon, which will open the block in the artery. Then it can insert something called a stent – which is a tube inserted into the artery to keep it open.

This video shows how it works:

  1. Thrombolysis – In this procedure a material is injected into the blood vessels, which causes the clot to “melt”. This opens the heart’s arteries back. While it sounds easier than the first method, it’s not as efficient, and not everyone is suitable for this procedure.
  2. Coronary artery bypass surgery (CABG) – Sometimes neither of the first two treatments fit. In this setting, a surgery has to be performed. In it, the chest is opened and the heart is exposed. The surgeon then takes an artery or vein from somewhere else in the body and implants it to the heart’s arteries. In this way, the occlusion is bypassed by a new, open, blood vessel.

Besides those, some drugs are given to everyone having a heart attack. They include aspirin (which stops the platelets from aggregating and so slows down the process), pain killers, oxygen and others.

What happens after treatment?

Without treatment, death rates are high for people who undergo a heart attack. But even with treatment, death can occur, especially before reaching the hospital. This is mainly due to complications that can occur as part of the heart attack, such as problems with the heart rhythm, failure of the heart’s muscle to pump properly, problems with the heart’s valves and others.


The bottom line – How do I avoid it?

The best way to avoid a heart attack is to prevent the process of atherosclerosis from happening.

If you do have atherosclerosis or if you had a heart attack before, you can prevent it from happening by visiting your doctor. They will prescribe some drugs for you (including statins, beta blockers, aspirin, and others. Taking these drugs regularly will lower your chances of getting a heart attack.