What Is Cardiogenic Shock?
Cardiogenic (kar-dee-oh-JE-nik) 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 (hy-poe-voe-LEE-mik) shock. This is
shock due to not enough blood in the body. The most common cause is severe
bleeding.
- Vasodilatory (VAZ-oh-DILE-ah-tor-ee) 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 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.
How the Heart Works
To understand cardiogenic shock, it's helpful to
understand how a normal heart works.
The heart is a muscle about the size of your fist.
It works like a pump and beats 100,000 times a day.
The heart has two sides, separated by an inner wall
called the septum. The right side of the heart pumps blood to the lungs to pick
up oxygen. Then, oxygen-rich blood returns from the lungs to the left side of
the heart, and the left side pumps it to the body.
The heart has four chambers and four valves and is
connected to various blood vessels. Veins are the blood vessels that carry
blood from the body to the heart. Arteries are the blood vessels that carry
blood away from the heart to the body.
A Healthy Heart Cross-Section
The illustration shows
a cross-section of a healthy heart and its inside structures. The blue arrow
shows the direction in which oxygen-poor blood flows from the body to the
lungs. The red arrow shows the direction in which oxygen-rich blood flows from
the lungs to the rest of the body.
Heart Chambers
The heart has four chambers or "rooms."
- The atria (AY-tree-uh) are the two upper chambers
that collect blood as it comes into the heart.
- The ventricles (VEN-trih-kuls) are the two lower
chambers that pump blood out of the heart to the lungs or other parts of the
body.
Heart Valves
Four valves control the flow of blood from the atria
to the ventricles and from the ventricles into the two large arteries connected
to the heart.
- The tricuspid (tri-CUSS-pid) valve is in the
right side of the heart, between the right atrium and the right ventricle.
- The pulmonary (PULL-mun-ary) valve is in the
right side of the heart, between the right ventricle and the entrance to the
pulmonary artery, which carries blood to the lungs.
- The mitral (MI-trul) valve is in the left side of
the heart, between the left atrium and the left ventricle.
- The aortic (ay-OR-tik) valve is in the left side
of the heart, between the left ventricle and the entrance to the aorta, the
artery that carries blood to the body.
Valves are like doors that open and close. They open
to allow blood to flow through to the next chamber or to one of the arteries,
and then they shut to keep blood from flowing backward.
When the heart's valves open and close, they make a
"lub-DUB" sound that a doctor can hear using a stethoscope.
- The first soundthe "lub"is made by
the mitral and tricuspid valves closing at the beginning of systole
(SIS-toe-lee). Systole is when the ventricles contract, or squeeze, and pump
blood out of the heart.
- The second soundthe "DUB"is made by
the aortic and pulmonary valves closing at beginning of diastole
(di-AS-toe-lee). Diastole is when the ventricles relax and fill with blood
pumped into them by the atria.
Arteries
The arteries are major blood vessels connected to
your heart.
- The pulmonary artery carries blood pumped from
the right side of the heart to the lungs to pick up a fresh supply of
oxygen.
- The aorta is the main artery that carries
oxygen-rich blood pumped from the left side of the heart out to the body.
- The coronary arteries are the other important
arteries attached to the heart. They carry oxygen-rich blood from the aorta to
the heart muscle, which must have its own blood supply to function.
Veins
The veins are also major blood vessels connected to
your heart.
- The pulmonary veins carry oxygen-rich blood from
the lungs to the left side of the heart so it can be pumped out to the
body.
- The vena cava is a large vein that carries
oxygen-poor blood from the body back to the heart.
For more information on how a healthy heart works,
see the Diseases and Conditions Index article on
How
the Heart Works. This article contains animations that show how your heart
pumps blood and how your hearts electrical system works.
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 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 (such as the brain and kidneys) 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 (plak) 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:
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 911 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. (See the National Heart, Lung, and Blood Institute's
"Your
Guide to a Healthy Heart.")
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 911 for help. You can begin to
receive life-saving treatment as soon as medical personnel arrive.
Key Points
- 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 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.
- The most common cause of cardiogenic shock is
damage to the heart muscle from a severe
heart
attack. However, less than 10 percent of people who have a heart attack
develop cardiogenic shock.
- Common 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 911 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.
- Blood pressure tests,
EKG
(electrocardiogram),
chest x ray,
echocardiography,
coronary
angiography, and blood tests are used to diagnose cardiogenic shock.
- Treatment for cardiogenic shock starts with
emergency life support to keep the patient alive. Once doctors know that a
person is in cardiogenic shock, they can use medicines, medical devices, and
different types of surgery to treat the underlying causes of the shock.
- 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. (See the National Heart, Lung, and Blood Institute's
"Your
Guide to a Healthy Heart.")
Links to Other Information About Cardiogenic Shock
NHLBI Resources
Non-NHLBI Resources
Clinical Trials
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