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.