What is Atherosclerosis and How Is it Related to High Blood Pressure?
One of the most serious health problems related to untreated high blood pressure is atherosclerosis, or plaque build-up in the arteries. When those blockages occur in the arteries that supply blood to the heart muscle, the end result is called coronary artery disease.
People with high blood pressure are more likely to develop coronary artery disease, because high blood pressure puts added force against the artery walls. Over time, this extra pressure can damage the arteries, making them more vulnerable to the narrowing and plaque buildup associated with atherosclerosis. The narrowed artery limits or blocks the flow of blood to the heart muscle, depriving the heart of oxygen.
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When the process is advanced enough, patients can experience angina, or chest pain, when they exert themselves. The hardened surface of the artery can also encourage the formation of small blood clots, potentially leading to a heart attack or stroke.
What Are the Symptoms of Atherosclerosis?
Atherosclerosis usually has no symptoms until the narrowed coronary arteries severely restrict blood flow to the heart. At this point, you may feel chest pain because not enough blood is reaching your heart, especially while you are exerting yourself or are under stress.
What Is a Heart Attack?
A heart attack is permanent damage to the heart muscle caused by a sudden loss of blood flow to the heart muscle. A heart attack occurs when a clot or spasm blocks an already narrowed coronary artery so that blood flow is severely reduced or completely interrupted. Left without oxygen, the portion of the heart muscle served by the blocked artery is injured.
How Is Atherosclerosis Diagnosed?
Atherosclerosis isn't usually diagnosed until a person complains of chest pain. At this point, the doctor may conduct tests to evaluate your risk for heart disease. These tests include:
Electrocardiogram (EKG or ECG): This test measures the electrical activity, rate, and rhythm of your heartbeat via electrodes attached to your arms, legs, and chest. This test may show if you've had a heart attack in the past or if you are currently having a heart attack, strain, or thickening of the heart muscle. Other than providing a snapshot of the function of your heart’s electrical system, the EKG can only indirectly point to other heart problems. It cannot predict your future risk.
Exercise stress test: During this test, you exercise on a stationary bicycle or treadmill to increase your heart rate and blood pressure while EKG readings are taken. This test is often performed with imaging techniques, such as an echocardiogram or nuclear scans, to provide better detection of heart disease. If artery blockages are present, the EKG, echocardiogram, and/or nuclear scan will show them, enabling your doctor to making the diagnosis of coronary artery disease. All of these tests are indirect; your arteries are not actually visualized during these evaluations. Because only advanced narrowing of the arteries lead to stress test abnormalities, a normal result, though reassuring and associated with a favorable prognosis in the near term, does NOT mean you don’t have ANY plaque deposits. It’s still important to control any heart disease risk factors you may have.
Cardiac catheterization: During this procedure, a catheter -- a small flexible tube -- is inserted into an artery and guided up to the coronary arteries, at which point dye is injected through the tube and observed as it flows inside those arteries. This allows the doctor an opportunity to directly locate and measure any blockages in the coronary arteries. During a cardiac catheterization, a cardiologist may also be able to open up any clogged arteries detected with a procedure called an angioplasty. This may also involve expanding a small metal mesh tube, called a stent, inside the blood vessel to better prop the artery open.
Echocardiogram: This test uses ultrasound waves to provide pictures of the heart's valves and chambers, giving information about chamber size and wall thickness and how blood is flowing within the chambers. Because this is such a safe, comprehensive and readily available evaluation, the echocardiogram is often used as the first test (after an EKG) to look for evidence of underlying heart problems. The coronary arteries are not seen during an echocardiogram, so unless a heart attack has already affected the heart, the presence of blockages cannot be made or excluded based upon this test alone.
Carotid ultrasound: This test uses ultrasound waves to provide pictures of blood flow in the arteries of the neck. Because atherosclerosis affects arteries in general, detecting blockages in the neck arteries suggests that it is highly likely that blockages are present in other parts of the circulatory system (including the coronary arteries).
Computed tomography (CT) scan: An X-ray and a computer are used to construct a cross-sectional image of the heart. This can provide information about the presence of calcium in heart arteries (an indication of underlying atherosclerosis). Some CT scanners are also able to provide much more detailed pictures of the heart arteries, yielding information similar to that obtained from a coronary angiogram.
Magnetic resonance arteriography (MRA): This test provides images of blood vessels to show where they may be blocked. In general, this is used to look at larger arteries (those of the neck or other parts of the body) rather than the small arteries supplying blood to the heart.