What is cardiogenic shock? Cardiology Basics

What is cardiogenic shock? Cardiology Basics

When the heart is not able to pump enough blood for perfusing the vital organs and the blood pressure falls, it is known as cardiogenic shock. Most important cause of cardiogenic shock is an acute myocardial infarction. Cardiogenic shock can also occur in other conditions like a fulminant myocarditis. In case of myocardial infarction, it is more likely to occur in those who are older, having multivessel coronary artery disease, and in those with a previous myocardial infarction. Cardiogenic shock is a potentially life threatening condition and needs urgent treatment. Even with treatment about half of those with cardiogenic shock might succumb.

Those with cardiogenic shock may have severe breathlessness, rapid thready pulse, hypotension, undue sweating, and cold clammy extremities. Altered sensorium and even loss of consciousness may occur due to severe cerebral hypoperfusion. Oliguria is another important manifestation of vital organ hypoperfusion.

Infusion of inotropes are usually given to enhance the blood pressure as an emergency measure. Devices like an intra-aortic balloon pump and percutaneous left ventricular assist device may be useful to some extent. Intra-aortic balloon pump uses intermittent inflation of a balloon attached to a catheter placed in the descending aorta, above the renal arteries and beyond the left subclavian artery. The balloon is inflated in diastole using the inert gas helium. It reduces left ventricular afterload and improves coronary perfusion as the diastolic pressure will become higher than systolic pressure. Some recent studies have questioned the role of IABP in cardiogenic shock.

If cardiogenic shock is due to acute myocardial infarction, immediate angiography, and primary angioplasty are useful.  In primary angioplasty, balloon catheters are inflated across the coronary obstruction. It is usually followed by insertion of a coronary stent to prevent recoil and closure of the vessel. The procedure is done under fluoroscopy in a cardiac catheterization laboratory.

Another option in case of refractory cardiogenic shock is an ECMO or extracorporeal membrane oxygenation. In veno-arterial ECMO, deoxygenated blood is drained from the femoral vein and oxygenated blood is delivered through a cannula introduced into the femoral artery. Veno-arterial ECMO supports both respiration and circulation. The 2017 guidelines for management of ST elevation myocardial infarction or STEMI, from the European Society of Cardiology gives a Class IIb recommendation for the use of ECMO in the management of refractory cardiogenic shock.