Heart Attack
Myocardial Infarction (MI)
Causes
A heart attack is caused when blood flow through one or more coronary arteries that supply blood to the heart is cut off. While blood flow can be blocked if the artery spasms and obstructs flow, most heart attacks are caused by blood clots (thrombosis) that form around the ruptured plaque, a buildup in the artery wall of a fatty material containing cholesterol, calcium, and other substances. Several factors contribute to a heart attack, including certain health issues and triggers.
A systemic problem
Plaque builds up in our arteries as we age, not just in the arteries that supply blood to the heart. This buildup of plaque, or “hardening of the arteries,” is called atherosclerosis, and it’s the same disease process that causes coronary artery disease (CAD), carotid artery disease, and peripheral artery disease (PAD). Blockages in the carotid arteries in the neck can cause a stroke. PAD is a condition in which blockages are present in the legs, feet, or arms or the arteries leading to the kidney, specifically, kidney (renal) artery disease. Anyone diagnosed with CAD is also at risk for carotid artery disease and PAD, and vice versa.
Plaque in the arteries is a fatty, waxy substance that forms deposits in your artery walls that can narrow the arteries and reduce blood flow. This is called atherosclerosis or “hardening of the arteries.” Plaque can also rupture and create a blood clot at the rupture site, as your body’s natural processes try to repair the “injury.” The blood clot can cut off blood flow through the artery and starve your body’s tissues of oxygen and nutrients. Thus, a ruptured plaque can be serious, as it’s the most common cause of a heart attack or stroke.
Risk factors
To lower your risk of a heart attack, you’ll want to reduce the risk factors that contribute to CAD and cardiovascular disease throughout your body.
Triggers
A trigger may contribute to a heart attack, but it’s not a cause in the same way as an underlying risk factor such as heredity or a disease process like atherosclerosis. Instead, a trigger is an event that starts a heart attack in the presence of an existing disease.
Some of the more common heart attack triggers include the following:
- Vigorous activity – Strenuous exercise or physical labor increases the demands placed on the heart. If someone has narrowed or blocked coronary arteries, blood flow will not be sufficient to support vigorous activity and heart functioning. One of the benefits of a regular exercise regimen is that people who exercise regularly are less likely to fall victim to heart attack and are more likely to recognize a change in exercise tolerance earlier in the disease process, leading to an earlier diagnosis of existing atherosclerosis. Overall, regular exercise is an important element in preventing cardiovascular disease.
- Shoveling snow – This is a vigorous activity, but it’s worth listing separately, as it is a common heart attack trigger. The weight of snow on a shovel, combined with the extra strain put on the heart by cold temperatures and the fact that many people who attempt to shovel snow don’t normally exercise, makes this a particularly dangerous activity.
- Stress – Stress is a known heart attack trigger, though more research is needed to determine exactly why. Research suggests that stress hormones and a stress-related elevation in blood pressure may trigger heart attacks. Extreme emotional or physical stress can also lead to stress cardiomyopathy, also known as broken heart syndrome (Takotsubo cardiomyopathy).