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cardiogenic shock





Contents
  • Causes of cardiogenic shock
  • Who is at risk?
  • Signs and symptoms
  • Diagnosis
  • Treatment
  • Prevention
  • Cardiogenic shock is a state in which a weakened heart isn't able to pump enough blood to meet the body's needs. It is a medical emergency and is fatal if not treated right away. The most common cause of cardiogenic shock is damage to the heart muscle from a severe heart attack.

    Not everyone who has a heart attack develops cardiogenic shock. In fact, less than 10 percent of people who have a heart attack develop it. But when cardiogenic shock does occur, it's very dangerous. For people who die from a heart attack in a hospital, cardiogenic shock is the most common cause.





    What is shock?

    The medical term "shock" refers to a state in which not enough blood and oxygen reach important organs in the body, such as the brain and kidneys. In a state of shock, a person's blood pressure is very low.

    Shock can have a number of different causes. Cardiogenic shock is only one cause of shock. Other causes of shock include:
    • Hypovolemic shock. This is shock due to not enough blood in the body. The most common cause is severe bleeding.

    • Vasodilatory shock. In this type of shock, the blood vessels relax too much and cause very low blood pressure. When the blood vessels are too relaxed, there isn't enough pressure to push the blood through them. Without enough pressure, blood doesn't reach the organs. A bacterial infection in the bloodstream, a severe allergic reaction, or damage to the nervous system (brain and nerves) may cause vasodilatory shock.
    When a person is in shock (from any cause), not enough blood or oxygen is reaching the body's organs. If shock lasts more than several minutes, the lack of oxygen to the organs starts to damage them. If shock isn't treated quickly, the organ damage can become permanent, and the person can die.

    Some of the signs and symptoms of shock include:
    • Confusion or lack of alertness
    • Loss of consciousness
    • A sudden, rapid heartbeat
    • Sweating
    • Pale skin
    • Weak pulse
    • Rapid breathing
    • Decreased or no urine output
    • Cool hands and feet
    If you suspect that you or someone with you is in shock, call 911 (or, outside the US, your own country's emergency phone number) and get emergency treatment right away. Prompt treatment can help prevent or limit lasting damage to the brain and other organs and can prevent death.


    Outlook

    In the past, almost no one survived cardiogenic shock. Now, thanks to improved treatments, around 50 percent of people who go into cardiogenic shock survive.

    The reason more people are able to survive cardiogenic shock is because of treatments (medicines and devices) that restore blood flow to the heart and help the heart pump better. In some cases, devices that take over the pumping function of the heart are used. Implanting these devices requires major surgery.


    What causes cardiogenic shock?


    Immediate causes

    Cardiogenic shock happens when the heart can't pump enough blood to the body. This mostly occurs when the left ventricle of the heart isn't working because the muscle isn't getting enough blood or oxygen due to an ongoing heart attack. The weakened heart muscle can't pump enough oxygen-rich blood to the rest of the body.

    In about 3 percent of the cases of cardiogenic shock, the right ventricle isn't working. This means the heart can't effectively pump blood to the lungs, where the blood picks up oxygen to bring back to the heart and the rest of the body.

    When the heart isn't pumping enough blood to the rest of the body, organs don't get enough oxygen and can be damaged. Some of the things that might happen include the following.
    • Cardiogenic shock may result in death if the flow of blood and oxygen to the organs isn't restored quickly. This is why emergency medical treatment is essential.

    • When organs don't get enough blood or oxygen and stop working, cells in the organs die, and the organs may never go back to working normally.

    • As some organs stop working, they may cause problems with other bodily functions. This, in turn, can make the shock worse. For example:
      • When the kidneys aren't working right, the levels of important chemicals in the body change. This may cause the heart and other muscles to become even weaker, limiting blood flow even more.

      • When the liver isn't working right, the body stops making proteins that cause the blood to clot. This can lead to more bleeding if the shock is due to blood loss.
    How well the brain, kidneys, and other organs recover depends on how long a person is in shock. The shorter the time in shock, the less damage to the organs. This is another reason why it's so important to get emergency treatment right away.


    Underlying causes

    The underlying causes of cardiogenic shock are conditions that weaken the heart and make it unable to pump enough blood and oxygen to the body.

    These conditions include:
    • Heart attack. Coronary artery disease (CAD) usually causes heart attack. CAD is a condition in which a material called plaque narrows or blocks the coronary arteries.

    • Serious heart conditions that may cause a heart attack and lead to cardiogenic shock, such as:
      • Ventricular septal rupture. This is when the wall between the two ventricles breaks down because cells in part of the wall have died due to a heart attack. If the ventricles aren't separated, they can't pump properly.

      • Papillary muscle infarction or rupture. This is when the muscles that help anchor the heart valves stop working or break because their blood supply is cut off due to a heart attack. When this happens, blood doesn't flow in the right way between the different chambers of the heart, and they can't pump properly.

    • Serious heart conditions that may happen with or without a heart attack, including:
      • Myocarditis, or inflammation of the heart muscle.
      • Endocarditis, or infection of the heart valves.
      • Arrhythmias, or problems with the speed or rhythm of the heartbeat.
      • Pericardial tamponade, or too much fluid or blood around the heart. The fluid squeezes the heart muscle so it can't pump properly.

    • Pulmonary embolism. This is a sudden blockage in a lung artery, usually due to a blood clot that traveled to the lung from a vein in the leg.

    Who is at risk for cardiogenic shock?

    The most common risk factor for cardiogenic shock is having a heart attack.

    If you've had a heart attack, the following factors can further increase your risk for cardiogenic shock:
    • Older age
    • Having a history of heart attacks or heart failure
    • Having coronary artery disease in all the major heart blood vessels

    What are the signs and symptoms of cardiogenic shock?

    A lack of blood and oxygen reaching the brain, kidneys, skin, and other parts of the body causes the symptoms of cardiogenic shock.

    The signs and symptoms of cardiogenic shock include:
    • Confusion or lack of alertness
    • Loss of consciousness
    • A sudden, rapid heartbeat
    • Sweating
    • Pale skin
    • Weak pulse
    • Rapid breathing
    • Decreased or no urine output
    • Cool hands and feet
    If you or someone with you is having these signs and symptoms, call right away for emergency treatment. Prompt treatment can help prevent or limit lasting damage to the heart and other organs and can prevent sudden death.


    How is cardiogenic shock diagnosed?

    The first step in diagnosing cardiogenic shock is to identify that a person is in shock. At that point, emergency treatment should be started.

    Once emergency treatment is started, doctors can look for the specific cause of the shock. If the reason for the shock is that the heart isn't pumping strongly enough, then the diagnosis is cardiogenic shock.

    Tests that are useful in diagnosing cardiogenic shock include:
    • Blood pressure. Using a simple blood pressure sleeve and stethoscope, doctors can check to see if a person has very low blood pressure, the most common sign of shock. This can easily be done before the patient goes to the hospital. Very low blood pressure also can have less serious causes, including simple fainting and side effects of medicines, such as medicines that treat high blood pressure.

    • EKG (electrocardiogram). This test detects and records the electrical activity of the heart, measuring the rate and regularity of the heartbeat. Doctors use EKG to diagnose severe heart attack and monitor your heart's condition.

    • Chest X-ray. This test takes pictures of organs and structures inside your chest, including the heart, lungs, and blood vessels. A chest X-ray shows whether the heart is enlarged or whether there is fluid in the lungs, which can be signs of cardiogenic shock.

    • Echocardiography. This test uses sound waves to create a moving picture of your heart. Echocardiography provides information about the size and shape of your heart and how well your heart chambers and valves are working. The test also can identify areas of heart muscle that aren't contracting normally. Not enough blood is flowing to these areas.

    • Coronary angiography. This test is an X-ray exam of the heart and blood vessels. The doctor passes a catheter (a thin, flexible tube) through an artery in your leg or arm to your heart. The catheter can measure the pressure inside the various chambers of your heart. A dye that can be seen on X-ray is injected into the blood through the tip of the catheter. The dye lets the doctor study the flow of blood through the heart and blood vessels and see any blockages that exist.
    Certain blood tests also are used to diagnose cardiogenic shock, including:
    • Arterial blood gas measurement. In this test, a blood sample is taken from an artery to measure oxygen, carbon dioxide, and pH (acidity) in the blood. Doctors look for abnormalities in these levels that are associated with shock.

    • Cardiac enzymes. When cells in the heart die, they release enzymes into the blood called markers or biomarkers. Measuring these markers can show whether the heart is damaged and the extent of the damage.

    • Tests that measure the function of various organs, such as the kidneys and liver. If these organs aren't working right, it could be a sign that they aren't getting enough blood and oxygen, which could be a sign of cardiogenic shock.

    How is cardiogenic shock treated?

    Cardiogenic shock is life threatening and requires emergency medical treatment. In most cases, cardiogenic shock is diagnosed after a person has been admitted to the hospital for a heart attack. If the person isn't already in the hospital, emergency treatment can start as soon as medical personnel arrive.

    The goals of emergency treatment for cardiogenic shock are first to treat the shock and then to treat the underlying cause or causes of the shock.

    Sometimes both the shock and its cause are treated at the same time. For example, doctors may quickly open a blocked blood vessel that's causing damage to the heart. Often, opening the blood vessel can get the patient out of shock with little or no additional treatment.


    Emergency life support

    Emergency life support treatment is required for any type of shock. This treatment helps get blood and oxygen flowing to the brain, kidneys, and other organs. Restoring blood flow to the organs is essential to keep the patient alive and to try to prevent long-term damage to the organs. Emergency life support treatment includes:
    • Giving the patient extra oxygen to breathe so that more oxygen reaches the lungs, the heart, and the rest of the body.

    • Giving the patient fluids, including blood and blood products, through a needle inserted in a vein (when the shock is due to blood loss). Putting more blood into the bloodstream can help get more blood to important organs and to the rest of the body. This is usually not done for cardiogenic shock because the heart can't pump the blood that's already in the body and too much fluid is in the lungs, making it difficult to breathe.

    Medicines

    During and after emergency life support treatment, doctors try to find out what is causing the shock. If the reason for the shock is that the heart isn't pumping strongly enough, then the diagnosis is cardiogenic shock.

    Depending on what is causing the cardiogenic shock, treatment may include medicines to:
    • Increase the force with which the heart muscle contracts
    • Treat the heart attack that may have caused the shock

    Medical devices and procedures

    In addition to medicines, there are medical devices that can help the heart pump and improve blood flow. The devices most commonly used to treat cardiogenic shock include:
    • Intra-aortic balloon pump. This device is placed in the aorta (the main blood vessel that carries blood from the heart to the body). A large balloon at the tip of the device is inflated and deflated in a rhythm that exactly matches the rhythm of the heart's pumping action. This helps the weakened heart muscle pump as much blood as it can, and gets more blood to vital organs such as the brain and kidneys.

    • Angioplasty and stents. Angioplasty is a procedure used to restore blood flow through blocked coronary arteries and to treat an ongoing heart attack. A stent is a small device that's placed in a coronary artery during angioplasty to help keep it open.

    Surgery

    Sometimes medicine and medical devices aren't enough to treat cardiogenic shock. Surgery can restore blood flow to the heart and the rest of the body and repair damage to the heart. Surgery can help keep a patient alive while recovering from shock and improve the chances for long-term survival.

    The types of surgery used to treat underlying causes of cardiogenic shock include:
    • Coronary artery bypass grafting. In this surgery, arteries or veins from other parts of the body are used to bypass (that is, go around) narrowed coronary arteries.

    • Surgery to repair damaged heart valves.

    • Surgery to repair a break in the wall between two chambers of the heart. This break is called a septal rupture.

    • Surgery to implant a device to help the heart pump blood to the body. This device is called a left ventricular assist device (LVAD) or mechanical circulatory assist. This surgery may be done if damage to the left ventricle is causing the shock. The implanted device is a battery-operated pump that takes over part of the pumping action of the heart.

    • Heart transplant. This is rarely done during an emergency situation like cardiogenic shock due to the other available devices and surgery options. Also, doctors need to do very careful tests to make sure a patient will benefit from a heart transplant and to find a matching heart from a donor. Still, in some cases, doctors may recommend a transplant if they feel it's the best way to improve the patient's chances of long-term survival.

    How can cardiogenic shock be prevented?

    The best way to prevent cardiogenic shock is to do as much as you can to lower your risk for heart disease and prevent a heart attack.

    If you have a heart attack, you should get immediate treatment to try to prevent cardiogenic shock and other possible complications.
    • Act in time. Know the warning signs of a heart attack so you can act fast to get treatment. Many heart attack victims wait 2 hours or more after their symptoms begin before they seek medical help. Delay in seeking treatment increases the chances of complications and death.

    • If you think you're having a heart attack, or if you have angina (chest pain or discomfort) that doesn't go away as usual when you take your angina medicine as directed, call 9𢴏 (in the U.S.) for help. You can begin to receive life-saving treatment as soon as medical personnel arrive.

    Related categories

       • HEART TOPICS
       • HEALTH AND DISEASE

    Source: U.S. National Heart, Lung and Blood Institute