Ejection Fraction

What Exactly Is EF, Anyway? 

You really have to follow this to understand what's going on with your heart. Come on, it ain't rocket science! Your heart circulates blood through 2 separate systems. The two chambers on top (atriums) are receiving stations for blood. The two lower chambers (ventricles) are pumping stations.
     Your left ventricle forces oxygen-rich blood into your arteries, which carry it throughout your body. The blood returns to the right atrium, which passes it down to the right ventricle. The right ventricle pumps this blood to the lungs, where it picks up oxygen. Oxygen-rich blood then returns to the left atrium, which dumps it into the left ventricle, and the cycle repeats. Valves between the chambers prevent "backwash."

When the left ventricle contracts, forcing blood out into the body, it's called "ejection" since it is "ejecting" the blood out into your arteries. Since the big pumper on the lower left is the one that pushes blood throughout your body, that is where they usually measure heart function - the left ventricle.
     That's the "ejection" part. The "fraction" part is because that pumping chamber (the left ventricle) never quite manages to pump out all the blood inside it - there's always a little bit left behind that lies around waiting for the next contraction. The amount your left ventricle does pump out per beat is called the "ejection fraction". It's X% (the amount pumped out) of the total amount of blood in the ventricle per heart beat.

Gimme a Number! 

If your heart pumps out 55% or more of the blood in your left ventricle on each beat, you have good heart function. When it falls below 55% on each beat, you're slipping. That means your heart muscle is too weak to force as much blood out on each contraction as it should. Now, if your EF sounds bad, don't despair. Eight years ago, my own EF was 13% and here I sit, typing this web page. ;-) My EF is now much improved.
     There is also an ejection fraction for the right ventricle. This measures how well it is pumping blood back to your lungs to pick up oxygen. It is called RVEF and is normally lower than LVEF. Most CHFers will deal mainly with LVEF, or Left Ventricular Ejection Fraction. Around here, that's what we mean by EF.

Low EF and Mortality 

If your EF measured low - say under 35% - this does not mean you are more likely to die! Other measurements may show increased risk for death - a high (over 130ms without pacing) QRS interval, high CgA level, low heart rate variability, T-Wave Alternans, very low Vo2max, etc,... However, EF is not a predictor of death. So, don't let a low EF panic you! Instead, work on raising it with meds therapy, low-sodium diet, well-planned exercise, and other life style changes such as stopping smoking, stopping drinking and losing excess weight.

Diastolic CHF Versus Systolic CHF 

The heart's pumping cycle has 2 phases - the filling-with-blood phase and the forcing-blood-out phase:

  1. The filling phase happens when the heart muscle relaxes, allowing blood to enter and fill it - called diastole (pronounced "die ass tuh lee"). The left ventricle fills up with blood.
  2. The emptying phase is usually thought of as the pumping phase - the heart muscle contracts (squeezes) to pump out (eject) blood. This phase of the heart's cycle is called systole (pronounced "sis tuh lee")

Most CHFers have systolic heart failure. That means the heart's left ventricle doesn't pump enough blood out into the body on each beat. My web site is pretty much devoted to systolic heart failure or "SHF". Why? Because until about a year ago, no one realized how common diastolic heart failure really is.
     Diastolic heart failure or "DHF" happens when your heart won't relax properly, so it can't fill up with enough blood. Of course, if it can't fill up with enough blood, it can't pump out enough blood. You wind up with many of the same problems and many of the same drugs are used to treat both diastolic and systolic heart failure. You can read about diastolic heart failure here.
     One catch to all this is that you can have a terrible case of DHF and still have a normal EF. So you see that a normal EF doesn't always mean you don't have heart failure. If you have systolic heart failure (SHF), your EF is probably reduced. However, a fairly good EF does not always mean a healthy heart, even in SHF! There are just too many factors at play in a person's body who has heart failure to assume much.
     As you can see, ejection fraction is not a very good way to define heart failure because there are too many ways EF can seem good even in a person with real nasty heart failure.

A Patient's Take On EF "Numbers" 

Many CHFers - including me - are convinced that EF varies - a lot. Dr. Marc Silver agrees. It varies from minute to minute, hour to hour, and day to day. That makes measuring it less important and our actual EF number less important as well. What is important is the trend of our EF.
     You can spot the trend of your EF by having it measured once every so often: every 6 months or every year for a couple of years after diagnosis; less if you are stable; more if you are not. This is called "serial" testing. Watch the number to see if it goes up or down over time. The number itself is less important. Any CHF specialist will agree with most of this, but many internists and MDs - being less familiar with CHF reality - assign too much importance to our EF and not enough to how we feel day in and day out. That's another good reason to see a CHF specialist instead of an internist or general cardiologist.
     In short, how you feel is waaaay more important than what your EF is. EF is important, but by no means something to get obsessed with. ;-)

EF versus How You Feel 

This article is by a CHF doc you may know as Gino. Although he has recently acquired additional responsibilities at his medical center, he takes time to answer our questions. Thank you, Gino! Keep in mind that I edit to keep medspeak under control on my pages. All mistakes are mine.

Jon: When I was diagnosed with CHF, my EF measured by cath was 13%. After meds took the extra fluid off me and reduced my heart rate, I felt really good. I could do daily tasks easily and without fatigue or shortness of breath. Over the next 5 years, taking an ACE inhibitor, beta-blocker, diuretic and digoxin, my EF slowly went up to 40%. However - and here's the rub - as my EF went up, my energy level and my quality of life went down.
     So I asked Gino, "Why does someone with systolic CHF often see a rise in EF over time but they can't do as much as easily as when their numbers were low?" In other words, "Why do I feel worse even though my EF is better?"

Gino: This is a hard matter to explain. Remember that EF is not a true measure of the heart's ability to contract. EF also depends a lot on the "load" on the heart. Load on the heart has 2 parts: 

Preload
occurs when blood enters the heart and fills it - often called the "relaxation" phase. This phase of the heart cycle is called diastole (pronounced "die ass tuh lee"). Blood entering the heart and filling it puts pressure on the ventricle in an outward direction, expanding it.
Afterload
occurs when the heart muscle contracts (squeezes) to pump out (eject) blood. This phase of the heart cycle is called systole (pronounced "sis tuh lee"). Adequate "ejection" of blood depends partly on the size of the heart's chambers and on the blood pressure required to eject the blood

If you reduce the amount of blood that has to be pumped per beat, you reduce preload. If you lower blood pressure and reduce the effects of remodeling, you reduce afterload. Diuretics, ACE inhibitors and beta-blockers accomplish these changes. So your heart failure meds increase your EF without actually increasing your heart's ability to pump more blood.
     This may in part explain why your EF can go up but you feel just as bad as ever. What we have learned from trials is that ACE inhibitors and beta-blockers improve EF more than your ability to function. Both drugs act on blood pressure at rest and during exertion. Beta-blockers also slow the heart's beats per minute.
     It is very common in CHFers for blood pressure and heart rate to not rise properly during exertion. This may cause fatigue since the skeletal muscles aren't getting a big enough increase in blood supply during exertion. In other words, we prefer to preserve the heart muscle itself rather than work it too hard to improve how other muscles function.
     Recently, we discovered that the blood vessels which supply skeletal muscles - and also the skeletal muscles themselves - are changed in CHF. These changes reduce your ability to function physically. Heart failure meds are not able to reverse these changes. Rehab (physical conditioning) may partly reverse them, though.
     Another reason you may feel worse with an improved EF is that you do less exercise and daily activities. Over time, your muscles lose tone. That makes them less able to effectively use the oxygen and nutrients they do get from your heart, and less able to rid themselves of fatigue poisons. You may gain weight from being inactive, which contributes to fatigue as well. This is called deconditioning.
     Although I have not completely answered your question, I think that no one has the entire "truth" in their pocket on this one today. Ciao, Gino.

Having CHF With A Normal EF 

This article is by a CHF doc you may know as Gino. Although he has recently acquired additional responsibilities at his medical center, he takes time to answer our questions. Thank you, Gino! Keep in mind that I edit to keep medspeak under control on my pages. All mistakes are mine.

The definition of EF on this page is very good, so I'll pass over the definition and methods used to measure it and I will go directly to the heart of the problem. ;-) 
     EF is a rough measure of heart function. Its value is that it is easy to measure with less expensive, less invasive methods like echocardiogram. If we look at the heart like the pump it is, we have to view it as two well-defined parts: the filling phase (diastole) and the emptying phase (systole). CHF may be caused by a problem in either one of these phases or in both.
     EF is a measure of the emptying phase, so your ejection fraction may be normal if your CHF is caused by problems with the heart's filling phase. This situation is common in older people with a history of high blood pressure or ischemia - chronic reduced blood flow to the heart.
     Since ischemia slows blood flow to the heart, it takes your left ventricle longer to fill. When you exercise, your heart beats faster, which gives your heart even less time to fill per cycle. If it doesn't have enough time to completely "relax" during each diastole, it may get "stiff." So the atrium - which fills the ventricle with blood - has to put out a lot of extra pressure to fill the ventricle. This high atrial pressure is transmitted backward to the lungs, causing congestion of the lungs. That messes up breathing and causes shortness of breath.
     The same thing happens in "stiff" hearts, often caused by long-term high blood pressure. There are several other illnesses like HCM that may cause heart failure with a normal EF. There are also conditions where the heart muscle is invaded by foreign substances or where lots of fibrous tissue causes problems. These make the heart "stiffer" so it can't completely fill even though it ejects blood normally.

EF is a rough measure of ventricular function but it tells nothing about where the blood goes! So in the case of valve problems, your heart is not functioning well because blood constantly flows back into the atrium. You may have a normal EF but not a healthy heart.
     EF is usually measured at rest. Some patients with atrial fibrillation may have a normal heart rate at rest but during exertion it really gets out of control. The same thing may happen with mitral valve insufficiency, due to high pressure in the heart's upper chambers (atriums).
     Many CHFers have lung problems that play a role in their difficulty during exertion. The same thing is true for being overweight. Anemia may play a role in reduced ability to perform effort, and severe anemia can cause heart failure even though you have high cardiac output. The same is true for a malfunctioning thyroid gland.
     Recent advances in understanding heart failure show that the muscles and their blood vessels also become less functional, regardless of ejection fraction. This may be reversed or stopped by a regular, correct exercise program. Finally, depression and anxiety may be relevant factors on a CHFer's perception of shortness of breath and ability to perform effort, regardless of EF.
     Ciao, Gino.

Updated February 28, 2004

All information on this site is opinion only. All concepts, explanations, trials, and studies have been re-written in plain English and may contain errors. I am not a doctor. Use the reference information at the end of each article to search MedLine for more complete and accurate information. All original copyrights apply. No information on this page should be used by any person to affect their medical, legal, educational, social, or psychological treatment in any way. I am not a doctor. This web site and all its pages, graphics, and content copyright © 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Jon C.

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