Heart failure: Clinical

Heart failure is when the heart can’t supply enough blood to meet the body’s demands.

A variety of heart diseases like ischemia and valvular disease can impair the heart’s ability to pump out blood, and over time can lead to heart failure.

This can happen in two ways, either the heart’s ventricles can’t pump blood hard enough during systole, called systolic heart failure, or not enough blood fills into the ventricles during diastole, called diastolic heart failure.

In both cases, blood backs up, causing congestion or fluid buildup, which is why it’s also often called congestive heart failure.

All right, so the heart needs to squeeze out a certain volume of blood each minute, called cardiac output, which is the heart rate - or the number of beats in a minute - multiplied by the stroke volume – or the volume of blood squeezed out with each heartbeat.

Then the ejection fraction is the portion of blood that’s pumped out of the left ventricle- in other words the stroke volume divided by the total left ventricular volume.

The ejection fraction is normally around 50 to 70%, between 40 to 50% is borderline, and anything below 40% is systolic heart failure or heart failure with reduced ejection fraction.

There’s also diastolic heart failure, or heart failure with preserved ejection fraction.