السبت، 11 يونيو 2011

Unstable Angina Pectoris - Unstable Angina


Overview, Causes, & Risk Factors

Unstable angina is a condition more serious than stable angina and less serious than an actual heart attack. Stable angina is chest pain from a temporary decrease in oxygen to the heart that is caused by exertion and goes away with rest. A heart attack is a prolonged decrease in oxygen to the heart that results in permanent damage to the heart.
What is going on in the body?
Atherosclerosis, or hardening of the arteries, is a condition in which fatty deposits, or plaque, form inside blood vessel walls. Atherosclerosis that involves the arteries supplying the heart is known as coronary artery disease. Plaque can block the flow of blood through the arteries. The tissues that normally receive blood from these arteries then begin to suffer damage from a lack of oxygen. When the heart does not have enough oxygen, it responds by causing the pain and discomfort known as angina.
Unstable angina occurs when the narrowing becomes so severe that not enough blood gets through to keep the heart functioning normally, even at rest. Sometimes the artery can become almost completely blocked. With unstable angina, the lack of oxygen to the heart almost kills the heart tissue.
What are the causes and risks of the condition?
The factors that increase the risk of unstable angina include:
  • cigarette smoking

  • high blood pressure

  • high blood cholesterol

  • male gender

  • increasing age

  • diabetes

  • lack of exercise

    • Symptoms & Signs

    What are the signs and symptoms of the condition?
    Symptoms of unstable angina may include:
  • chest discomfort including chest pain, pressure, or heaviness with less and less exertion

  • chest discomfort that does not go away with the usual treatment

  • chest discomfort that occurs at rest

  • shortness of breath

  • nausea and vomiting

  • excessive sweating

  • extreme anxiety or a sense of impending doom

    • Diagnosis & Tests

    How is the condition diagnosed?
    The diagnosis of unstable angina begins with a careful history of the person's symptoms and a physical examination. Unstable angina is usually diagnosed when:
  • a person with stable angina has a sudden increase in the number or severity of episodes of chest pain over the previous days or weeks

  • a person without angina develops increasing episodes of chest pain or chest pain at rest

  • a person, who may or may not have had angina in the past, develops prolonged chest pain but does not show evidence of a heart attack


    • The healthcare provider may order several diagnostic tests, including:
  • an electrocardiogram, or ECG, which is a recording of the electrical activity of the heart. An ECG is usually normal when a person has no chest pain and often shows certain changes when pain develops.

  • a cardiac catheterization, which is an X-ray procedure that is used to look for narrowed coronary arteries. A contrast agent is injected so the doctor can watch blood flow through the heart and its arteries.

  • various blood tests

    • Prevention & Expectations

    What can be done to prevent the condition?
    A person may reduce the risk for developing unstable angina by:
  • following the healthcare provider's recommended treatment for stable angina

  • not smoking

  • controlling high blood pressure

  • controlling blood cholesterol

  • controlling diabetes

  • exercising regularly

  • eating a diet designed to minimize heart disease


    • What are the long-term effects of the condition?
    Unstable angina that is not controlled quickly can lead to a heart attack.
    What are the risks to others?
    Unstable angina is not contagious and poses no risks to others.

    Treatment & Monitoring

    What are the treatments for the condition?
    A person who has unstable angina is usually hospitalized. This allows the healthcare provider to determine if the person is having a heart attack, which can cause the same symptoms as unstable angina. The provider will attempt to optimize the person's medication regimen. The types of medications include the following:
  • nitroglycerin, to expand the small arteries and veins

  • beta-blockers, to reduce the work of the heart

  • blood thinners, to reduce the chance of clotting in the already narrowed arteries


    • Calcium channel blockers, such as diltiazem, nifedipine, or verapamil, have been used for over 20 years to open the coronary arteries and lower high blood pressure. However, the findings of 2 recent studies have shown that people who take a calcium channel blocker have a much higher incidence of complications than people taking other medications for coronary artery disease and high blood pressure. One study, for example, found that the risk of heart attack was 27% greater and the risk of congestive heart failure was 26% higher for those taking a calcium channel blocker. The American Heart Association recommends discussing risks and benefits of the medication with the healthcare provider.
    Sometimes the even the best combination of medications fails to control angina. In this case, surgery may be used to restore blood flow to the affected areas of the heart. Common procedures include:
  • percutaneous transluminal coronary angioplasty, or PTCA. In this procedure, a tube containing a balloon is inserted into the blocked artery and inflated. This reopens the artery and allows blood to flow.

  • heart bypass surgery, also known as coronary artery bypass graft or CABG. In this procedure, veins taken from the legs or arteries taken from the chest are used to bypass the narrowed or blocked portion of the arteries in the heart.

  • a stent, or narrow tube, which is placed into the artery at the reopened area to keep it from narrowing again

  • laser surgery, which uses light waves to dissolve plaque

  • atherectomy, a surgical procedure in which plaque that causes narrowing of a blood vessel is removed


    • What are the side effects of the treatments?
    Beta-blockers can cause:
  • a slow heartbeat

  • low blood pressure

  • depression

  • erectile dysfunction

  • unpleasant dreams


    • Calcium channel blockers can cause:
  • flushing

  • nausea

  • headache

  • swelling of the ankles

  • low blood pressure

  • weakness

  • a higher risk of heart attack and congestive heart failure


    • Nitrates can cause headaches and low blood pressure. Aspirin and warfarin increase the risk of bleeding. Surgery can result in infection, bleeding, and allergic reaction to anesthesia.
    What happens after treatment for the condition?
    A person whose unstable angina has been relieved will be monitored in the hospital to be sure the treatment continues to work. If the person has had surgery, the healthcare provider will also check to be sure that the blood flow does not suddenly become blocked again. A cardiac rehabilitation program will be started and will continue after the person leaves the hospital.
    A person with unstable angina should make every effort to reduce coronary risk factors. This may include the following: smoking cessation, control of other diseases such as diabetes and high blood pressure, and following a healthy diet to minimize heart disease. Medications may need to be adjusted to achieve the best response.
    How is the condition monitored?
    A person who has been treated for unstable angina will periodically have an ECG done during exercise. This will show how the heart is working with the remaining blood supply. Cardiac catheterization may need to be repeated in the future, especially if chest discomfort returns. Any new or worsening symptoms should be reported to the healthcare provider.

    Attribution

    Author:William M. Boggs, MD
    Date Written:
    Editor:Ballenberg, Sally, BS
    Edit Date:11/29/00
    Reviewer:Eileen McLaughlin, RN, BSN
    Date Reviewed:07/05/01
    Sources
    Scientific American Medicine 2000 (updated monthly)
    Medical Knowledge Self Assessment Program (MKSAP 11) 1998
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