Cardiogenic shock also sometimes known as “pump failure” is a condition of diminished cardiac output that severely impairs cardiac perfusion. It reflects severe left-sided heart failure.
- Inability to contract. When the myocardium can’t contract sufficiently to maintain adequate cardiac output, stroke volume decreases and the heart can’t eject an adequate volume of blood with each contraction.
- Pulmonary congestion. The blood backs up behind the weakened left ventricle, increasing preload and causing pulmonary congestion.
- Compensation. In addition, to compensate for the drop in stroke volume, the heart rate increases in an attempt to maintain cardiac output.
- Diminished stroke volume. As a result of the diminished stroke volume, coronary artery perfusion and collateral blood flow is decreased.
- Increased workload. All of these mechanisms increase the heart’s workload and enhance left-sided heart failure.
- End result. The result is myocardial hypoxia, further decreased cardiac output, and triggering of compensatory mechanisms to prevent decompensation and death.
The causes of cardiogenic shock are known as either coronary or non-coronary.
- Coronary. Coronary cardiogenic shock is more common than noncoronary cardiogenic shock and is seen most often in patients with acute myocardial infarction.
- Noncoronary. Noncoronary cardiogenic shock is related to conditions that stress the myocardium as well as conditions that result in an ineffective myocardial function.
Cardiogenic shock can result from any condition that causes significant left ventricular dysfunction with reduced cardiac output.
- Myocardial infarction (MI)
- Myocardial ischemia
- End-stage cardiomyopathy