Myocardial Ischemia: Information on Causes, Diagnosis & Treatments
Myocardial ischemia (cardiac ischemia) occurs when the flow of blood is reduced or restricted to the heart muscle. The action is a response to inadequate oxygen supplied to the heart caused by a complete or partial blockage of the coronary (heart) arteries. The event can cause considerable damage to the heart muscle and reduce its capacity to pump blood efficiently. If the blockage comes on suddenly and severely, it can produce a heart attack or serious abnormal heart rhythms.
Many individuals experience episodes of ischemia without ever knowing it because there is no pain or prior warning. Individuals with angina may also have episodes of ischemia that were never diagnosed. The condition is usually diagnosed by the patient wearing a Holter monitor or performing an exercise stress test while being monitored and evaluated.
- Who Is at Risk for Myocardial Ischemia?
- Common Symptoms
- Diagnosing Myocardial Ischemia
- Myocardial Ischemia Treatments
Who Is at Risk for Myocardial Ischemia?
While any individual can suffer myocardial ischemia, there are specific risk factors that increase the potential chance of developing the condition. Some of these include:
- Smoking Tobacco Products – Long-term direct exposure (smoking) or indirect exposure (secondhand smoke) can damage the artery's interior walls. The body responds to the damage by depositing cholesterol and other substances to rebuild the interior of the coronary artery which restricts blood flow and increases the potential risk of developing blood clots in the coronary arteries.
- Diabetes – Sufferers of Type I and Type II diabetes have an increased potential risk of experiencing heart problems including myocardial ischemia and heart attacks.
- High Blood Pressure – Chronic high blood pressure can eventually accelerate the development of atherosclerosis, causing considerable damage to coronary arteries.
- High Blood Triglyceride Levels – Body fats, including triglycerides are known to contribute to our atherosclerosis that eventually leads to Myocardial ischemia.
- High Blood Cholesterol Levels – The narrowing of coronary arteries is usually caused by the buildup of cholesterol levels, especially LDL (low-density lipoprotein) bad cholesterol in the bloodstream. Elevated levels of bad cholesterol are often the result of consuming a diet high and saturated fats or as an inherited condition.
- Lack of Physical Activity – Living an inactive lifestyle can significantly contribute to elevated triglyceride and cholesterol levels that eventually lead to obesity. Individuals should participate in routine aerobic exercises that focus on cardiovascular fitness. This can decrease the potential risk of experiencing a heart attack for myocardial ischemia. Routine exercise can also lower chronic high blood pressure levels.
- Waist Circumference – Individuals whose waist measures more than 35 inches in women and 40 inches in men have an increased potential risk of developing heart disease, myocardial ischemia, and high blood pressure.
- Obesity – Being extremely overweight, obese, or morbidly obese has been linked to high blood cholesterol levels, high blood pressure, and diabetes, which can all contribute to heart attacks and myocardial ischemia.
The condition can develop slowly as the body's coronary arteries become partially or completely blocked over time. Or, the condition can happen quickly when there is a sudden and severe block in the artery. The known causes of myocardial ischemia (cardiac ischemia) that might be associated with the risk factors listed above include:
- Atherosclerosis (coronary artery disease) – This condition builds plaque on the walls of the arteries by using cholesterol and other substances that restrict blood flow. Coronary artery disease is the major cause of myocardial ischemia.
- Coronary Artery Spasm – When the muscles in the arterial wall briefly tighten, the sudden event can temporarily prevent or decrease blood flow to portions of the heart muscle. Most cases involving myocardial ischemia are not caused by coronary artery spasms.
- Blood Clots – Atherosclerosis, where plaque builds up on the interior walls of the artery, can rupture and create a blood clot that has the potential of blocking the artery and causing severe, sudden myocardial ischemia. Without treatment, this can result in a heart attack. On rare occasions, the blood clot can travel out of the coronary artery and relocate to other parts of the body including a lung or brain.
Other causes that produce chest pain associated with heart attacks and myocardial ischemia are often triggered by specific events including cocaine use, emotional stress, physical exertion, and cold temperatures.
Many individuals who experience myocardial ischemia never display any kinds of symptoms or signs. This is often referred to as silent ischemia. However, when the symptoms do display themselves, they typically present as chest pain or pressure, usually on the body's left side (angina pectoris). However, there are other symptoms that are commonly experienced by older individuals, those with diabetes, and women. These include:
- Vomiting and nausea
- A racing heartbeat
- Arm or shoulder pain
- Jaw or neck pain
- Shortness of breath during physical activity
The symptoms associated with myocardial ischemia can be prevented if the individual quits smoking, begins an exercise program, modifies their diet, and routinely visits their health care provider to learn about their potential risk of developing heart disease or suffering a heart attack or myocardial ischemia.
Diagnosing Myocardial Ischemia
Diagnosing myocardial ischemia (cardiac ischemia) is relatively straightforward. The doctor will begin by gathering a comprehensive family and personal medical history before performing a complete physical examination. If the doctor determines that the patient has specific risk factors including a family history of heart conditions and/or the physical examination leads toward a diagnosis of heart problems, the physician will usually recommend numerous procedures and tests that include:
- ECG (Electrocardiogram) – This test records the heart's electrical activity through attached electrodes on the skin. The machine can determine certain abnormalities of the heart that may indicate that the patient is susceptible to experience myocardial ischemia.
- Echo (Echocardiogram) – Using a machine that generates sound waves, the technician will use a wand-like device on the chest over the heart to capture moving video images of the heart muscle. This test can also identify any damage that occurred to the heart muscle or provide information to the doctor if the heart is not pumping normally.
- Nuclear Scan – This procedure requires an injection of tiny amounts of radioactive substances into the bloodstream. The patient then exercises while the radioactive tracer is monitored through a machine as a substance flows through the lungs and heart. This test and identify blood flow issues.
- Cardiac CT (Computerized Tomography) Scan – This test can help identify the presence of coronary atherosclerosis (coronary artery calcification).
- Coronary Angiography – The technician can inject the dye into the bloodstream by the vessels of the heart and use an X-ray machine to capture angiograms (X-ray images) that provide detailed information on the interior of the blood vessels.
- Stress Test – Various tests can monitor breathing, blood pressure, and heart rhythm while the patient exercises on a treadmill or stationary bike. The exercise increases the heart rate making it pump faster harder than usual to detect any heart issues that might not otherwise be identified.
Myocardial Ischemia Treatments
Any treatment the doctor recommends will be designed to improve the flow of blood to the heart muscle. The type of treatment that might include surgery, medications or both is often dependent on the severity of the condition. The doctor may recommend aspirin, nitrates, calcium channel blockers, beta-blockers, ACE inhibitors, cholesterol lowering drugs, or ranolazine to ease the symptoms of angina. Surgical recommendations might include angioplasty, stenting, coronary artery bypass surgery, and enhanced external counterpulsation.