Category Archives: Health & Fitness explainer

What your doctor may do to diagnose and treat heart disease, and what YOU should do

As Heart Month draws to a close, it’s worth understanding a bit more about the tools your doctor may use to diagnose and treat heart disease or a heart attack. And, equally important, what you can (and should) do if you have a heart attack help prevent it from happening again.


Coronary_angiography_of_a_STEMI_patient,_showing_partial_occlusion_of_left_circumflex_coronary_artery


Coronary artery disease or heart disease is caused by atherosclerosis, a process which involves the accumulation of cholesterol plaques in the arteries that supply blood to the heart. These plaques can narrow the blood vessels and reduce blood and oxygen delivery to the heart, leading to symptoms like chest pain (ischemia). The plaques can also rupture and form a blood clot, blocking oxygen delivery and causing a myocardial infarction—a heart attack.

If you experience symptoms such as chest pain or have a high risk of heart disease due to family history and other risk factors, your doctor may recommend a diagnostic test. In a graded exercise test (GXT), or “stress” test, a person exercises, typically walking on a treadmill, at increasing speed and grade while heart rate, blood pressure, and heart rhythm are monitored by a doctor or exercise physiologist.

Stress_test

Changes in these variables, as well as the person’s exercise capacity, can be signs of ischemia and heart function. Often, a GXT is combined with another diagnostic technique such as nuclear imaging, which shows areas of the heart that do not receive enough blood flow, or an echocardiogram that uses ultrasound to show the heart beating and ejecting blood.

Based on the GXT results a cardiologist may recommend an angiogram, in which a catheter is inserted into an artery and threaded into the coronary arteries, dye is injected, and the coronary arteries are viewed through X-ray imaging. This allows cardiologists to actually see the extent of the narrowing in the coronary arteries.

You can been diagnosed with heart disease based on the results of an angiogram or if you had a heart attack. During the angiogram a cardiologist can perform an angioplasty in which a balloon catheter is inflated to open narrowed arteries. A mesh stent may also be placed to help keep the vessel open for longer. In other cases coronary artery bypass surgery may be indicated. Considered open heart surgery, this procedure actually bypasses narrowed sections of coronary arteries using another vessel, typically a leg vein. Both angioplasty and bypass surgery can restore adequate blood flow to the heart and treat ischemia and heart attacks.

Many people consider the treatment complete after the heart attack has ended and the angioplasty or bypass surgery is complete. The truth is that the long-term outcomes are largely based on what happens next. Traditionally, heart disease patients were told to rest and not stress their hearts, a belief that many still hold today. But exercise-based cardiac rehabilitation programs are key to improving heart health and preventing future complications.

Most cardiac rehabilitation programs include several phases. Phase I programs start in the hospital and focus on getting out of bed and performing self-care activities and some walking. Phase II cardiac rehab involves closely-monitored exercise, usually for 12 weeks following a heart attack or surgery. Phase III involves longer exercise sessions with greater independence and transitions into Phase IV, a lifelong exercise program. Education about exercise, nutrition, weight control, stress management, proper medication use, and psychosocial wellbeing are essential in all phases of cardiac rehabilitation.

The benefits of cardiac rehabilitation are well-established through research and practice. In fact, many patients credit cardiac rehabilitation with saving their lives, even if they had bypass surgery. Despite this, less than a third of patients who are eligible for cardiac rehabilitation actually attend a program.

If you or someone you know has had a heart attack or surgery, encourage them to ask their doctor about cardiac rehabilitation—it is likely to be the best way to improve quality of life and avoid future heart problems.

What you need to know about heart disease

February is American Heart Month, a time to raise awareness about heart disease, the leading cause of death among adults in the United States. Heart disease, sometimes called coronary heart disease or coronary artery disease, is responsible for nearly 375,000 deaths each year, mostly from heart attacks. Over 13 million adults have been diagnosed with heart disease and, if other cardiovascular diseases like high blood pressure, heart failure, and stroke are included, that number jumps to 80 million. (more statistics are available from the American Heart Association)

The process that leads to heart disease is called atherosclerosis and is characterized by the accumulation of cholesterol-containing plaques in the coronary arteries, the vessels that supply blood to the heart. These plaques narrow the vessels and reduce the amount blood delivered to the heart. The heart requires a constant supply of oxygen to beat and any narrowing in the vessels reduces blood flow and interferes with normal heart function. A decrease in oxygen delivery can cause chest pain (angina pectoris), especially during activity or exertion. It is usually relieved with rest, but can limit normal activities. A complete blockage in blood flow causes a heart attack, also called a myocardial infarction or MI, in which the heart muscle is damaged, sometimes permanently. Many MIs lead to death because dangerous arrhythmias—abnormal heart rhythms—develop that lead to cardiac arrest.

The traditional view of heart disease holds that the cholesterol plaques progressively narrow the arteries until they close completely, a process similar to a blockage in a pipe in your house. It turns out that the process of atherosclerosis is more complex. In fact, most heart attacks occur because of vessels that are around 50% blocked.

Current evidence shows that inflammation plays an important role in the accumulation of plaque in the vessel walls. Additionally, inflammation plays a role in making the plaques unstable and prone to rupture, resulting in a blood clot in the artery which completely blocks the flow of blood leading to a heart attack. This makes more sense if you think of the inside of a blood vessel like your skin. A cut on your finger results in inflammation and the formation of a blood clot which stops blood flow. A similar process occurs inside the coronary arteries to lead to an MI.

The process that occurs in coronary arteries also takes place in other vessels. A blood clot that forms in a vessel in the brain can cause a stroke, sometimes called a “brain attack” because the process is similar to a heart attack. Narrowed vessels that reduce blood flow to the brain can cause a reversible condition called a transient ischemic attack (TIA) or mini-stroke. Narrowed arteries in the legs can cause muscle pain during exercise or activity.

Atherosclerosis is a process that starts when we are young and progresses as we age. It generally doesn’t cause symptoms like chest pain until the arteries are at least 70% narrowed, so most people are unaware that it is happening. The process is accelerated by conditions like obesity, diabetes, high cholesterol, and high blood pressure as well as risk factors like a high fat diet, lack of exercise, and smoking.

Genetics play a role, too, but since you can’t change your genes, the emphasis is placed on factors that you can control. It turns out that making lifestyle changes can greatly reduce your risk of heart attack, and may even reverse the process that causes heart disease.

I will continue to celebrate Heart Month with more information about how to assess your risk for heart disease and what you can do to prevent and treat heart disease.

 

Your metabolism (and how to speed it up)

Many people are interested in speeding up their metabolism in an effort to lose weight. There are drugs, supplements, and even certain foods that are thought to increase metabolism. The effectiveness of many of these things is unproven and some may actually be dangerous. The goal of this article is to explain what the term “metabolism” really means and how it can be changed.

Metabolism refers all of your body’s processes that expend energy, or burn calories. Practically, this is how much carbohydrate, fat, and protein is burned throughout the day to provide energy for your cells. If you expend more energy than you consume in your diet, you will lose weight.

The amount of energy you expend in a day is composed of three main components: your resting metabolic rate (RMR), something called the thermic effect of food (TEF), and the energy you expend in activity.

Resting metabolic rate (RMR) is sometimes called the basal metabolic rate (BMR), but many people refer to it as their “metabolism.” No matter which name is used, it refers to the calories you burn at rest. It represents the energy needed to maintain your essential body functions: heart rate, breathing, body temperature, and normal cellular processes.

The RMR is important because it represents about 60–70% of the total calories a typical person burns in a typical day. Even though RMR is important, you shouldn’t worry about it too much.

First, it is difficult to change. RMR is based mostly on your lean body mass, so the only way to increase it is to gain muscle mass. While this is a good goal, it is challenging to do, especially while you trying to losing weight.

Second, although it does vary among people, it isn’t as different as people like to think. It is easy to think that someone who gains weight has a “slow metabolism” or that someone who is thin must have a “fast metabolism.” In reality, the RMR probably isn’t much different, certainly when you take lean body mass into account. The explanation for the differences in weight among people probably has more to do with what they eat and how active they are.

The thermic effect of food (TEF) represents the energy needed to digest, absorb, and store the nutrients you eat. It accounts for only about 10% of your total energy expenditure and it is practically impossible to change, so you can ignore it.

Activity is the most variable component of energy expenditure and the one you can most readily change. Obviously, it will vary based on how active you are, but for most people it accounts for 20–30% of total energy expenditure.

Activity includes both purposeful movement such as exercise and doing work or tasks that require you to move. Activity also includes non-exercise activity thermogenesis or NEAT, the calories you burn when you move around, but not in a purposeful way. Maintaining your posture when sitting or standing, fidgeting in your chair, or other light movements count as NEAT.

The surest way for you to increase your metabolism is to limit the time you spend sitting, be active as possible at all times, and dedicate time to exercise every day. Doing prolonged aerobic exercise such as walking, jogging, or exercise classes directly burns calories and including strength training will help increase your muscle mass, which can increase up your RMR.

The bottom line is that speeding up your metabolism requires you to move. So, get up off the couch and go for a walk!