Cardiogenic shock happens when your heart can't pump enough blood to the rest of your body. Most commonly, cardiogenic shock happens when your heart's main pumping chamber, the left ventricle, is damaged due to a lack of oxygen caused by a heart attack.
A heart attack occurs when one or more of the arteries supplying your heart with oxygen-rich blood (coronary arteries) become blocked. Over time, a coronary artery can become narrowed from the buildup of cholesterol. This buildup collectively known as plaques in arteries throughout the body is called atherosclerosis.
During a heart attack, one of these plaques can rupture and a blood clot forms on the site of the rupture and blocks the flow of blood through the artery. Without oxygen-rich blood circulating to that area of your heart, the heart muscle can weaken and progress into cardiogenic shock.
Rarely, cardiogenic shock happens when your heart's right ventricle is damaged. Your heart's right ventricle sends blood to your lungs to receive oxygen before being pumped to the rest of your body. Damage to the right ventricle makes it so your heart can't effectively pump blood to your lungs, so your body doesn't get sufficient oxygen.
Although heart attacks are the most common cause, cardiogenic shock can also occur due to other conditions, such as inflammation of the heart muscle (myocarditis) or infection of the heart valves (endocarditis). Other causes include drug overdoses or poisoning with substances that can affect your heart's pumping ability.