Diastolic Heart Failure vs. Systolic Heart Failure

Cardiology, Heart Failure

Heart failure is defined as a condition where the heart fails to give the body what it needs. This is not the same thing as a heart attack, which many people think, but it is a serious problem of its own. In fact, heart failure is one of the most difficult and costly problems doctors treat in the United States. The heart can fail in different ways.  Situations that lead to heart failure are complex, but basically you  can separate the problem into two different types: a weak heart and a stiff heart. In medicine we call these two categories by the terms we use to describe the way the heart works: systole or systolic heart failure and diastole or diastolic heart failure. 

Normal heart function is a cycle between systole and diastole.


Normal heart function

  • Systole

    Greek for “send to,” the word for the squeezing action of the heart. When the heart squeezes it sends blood towards the body.

  • Diastole

    Greek for “to expand” or “separate,” the relaxing of the heart muscle after it squeezes

. When the heart expands it “sucks” blood out of the lungs.

 How does heart failure happen?

Systolic heart failure happens when the heart cannot squeeze well.   Diastolic heart failure happens when the heart cannot relax. 

It’s easy for most people to imagine the heart not meeting its goal because it cannot squeeze. But people have more trouble understanding why not being able to relax causes a problem. Also, one might think that the diastolic form of heart failure is rare, but this is not the case. About half of the cases doctors encounter in the hospital are the diastolic type. Even though these are two very different situations, they both can cause the same symptoms. Symptoms of heart failure can be recognized by a person who knows them, and are described in another tablet. It is also important to realize that these two forms of heart failure do not necessarily happen alone. The heart can fail in both ways at the same time.

How does the heart pump our blood through the body?

Picture a tennis ball with a hole in one side. If we squeeze the tennis ball, it will get smaller, and the air insidel will get pushed out through the hole. Then as the ball gets big again, it sucks air back inside. The heart works the same way. The heart is a ball of muscle. When the heart muscle squeezes, it gets smaller, so the blood inside gets pushed out under the pressure. After it squeezes, the heart relaxes and expands, filling with fresh blood ready to be pushed out again. The heart pushes blood out when it squeezes, then pulls blood from the lungs when it relaxes. It works arounde the clock to keep our blood moving through the body.

How can your heart pump fail?

The term “C.H.F.” or congestive heart failure does not specify what type of heart failure a person has.  “Congestive” describes the fact that the symptoms it produces are caused by the accumulation of water in the lungs and the rest of the body.

Systolic Heart Failure: The heart cannot squeeze well

If the heart cannot squeeze, then it cannot push the blood out of itself. This will make the blood back up in the lungs—flooding them. About half the people with heart failure have a heart that cannot squeeze well. This happens for a variety of reasons, most commonly after a heart attack damages part of the heart muscle. Diastolic heart failure is often referred to by different names including a “stiff heart”, diastolic CHF, and diastolic dysfunction. 

Systolic heart failure happens when the heart cannot squeeze well.

Diastolic Heart Failure: The heart cannot relax well

Sometimes the heart becomes hard and stiff, so it is not able to relax and pull in blood. This means the heart cannot pull blood out of the lungs. About half the people with heart failure have this problem where the heart cannot relax well. The condition happens for a variety of reasons, but it occurs most often in older people and those with long-standing high blood pressure and poorly controlled diabetes. Systolic heart failure is often refered to as a “weak heart”and systolic HF.

Diastolic heart failure happens when the heart cannot relax well

Regardless of the mechanism that causes heart failure, whether it is systolic or diastolic, the symptoms of heart failure are the same.

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Last Modified: Jul 7, 2018 @ 1:29 pm
About the Author

Jose Taveras M.D. F.A.C.C.


Dr Taveras works as a cardiologist caring for spanish speaking communities in the Bronx. He completed a dual residency in Internal Medicine and Pediatrics and then served as chief resident of internal medicine at the St. Vincent’s Catholic Medical Center of New York. He went on to specialize in cardiovascular disease at NYU Winthrop Hospital , under the mentorship of Dr. Kevin Marzo, chief of Cardiology at Winthrop. He is board certified in both internal medicine and cardiovascular diseases, and sub specializes in echocardiography, nuclear cardiology and computed tomography of the heart. Apart from his work in community outreach, Dr. Taveras' career focuses on innovation and technology. Dr. Taveras is a fellow of the American College of Cardiology. 

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