Types of heart failure
Heart failure occurs when your heart loses its ability to pump blood efficiently. Decreased pumping function by the left ventricle occurs in two major ways:
- Systolic heart failure.Your ventricle does not squeeze forcefully enough during systole, which is the phase of your heartbeat when your heart pumps blood.
- Diastolic heart failure.Your ventricle does not relax properly during diastole, which is the phase of your heartbeat when your heart fills with blood.
What happens in systolic heart failure? Systolic heart failure occurs when your left ventricle pumps less blood than normal. There are many different problems that can cause your left ventricle to pump less efficiently during systole. For example, if part of your heart muscle is damaged from a heart attack, it may not be able to contract as well as it usually would.
What happens in diastolic heart failure?Diastolic heart failure occurs when less blood fills the left ventricle before it contracts again. As with systolic heart failure, there are many different problems that can impair your left ventricle's ability to fill properly with blood during diastole. For example, chronic high blood pressure can cause your heart muscle to become stiff or thickened so that it cannot relax properly, which limits how much blood fills the left ventricle.
What is high-output heart failure?A small percentage of people with heart failure actually have a problem called high-output heart failure. With high-output heart failure, the body's need for blood is unusually high. The heart may be working well otherwise, but it cannot produce a high enough cardiac output to keep up with this extra need. Less than 1% of people with heart failure have high-output heart failure.
There are a variety of conditions that can significantly increase the body's need for blood and oxygen, resulting in high-output heart failure. These conditions include anemia, hyperthyroidism, and pregnancy. Although the causes of high-output heart failure are different from the cause of other types of heart failure, the end result is the same: Your heart is not supplying enough blood to meet your body's needs. High-output heart failure results in the same classic symptoms of heart failure, including fatigue and shortness of breath.
What is right-sided heart failure?Most people develop heart failure because of a problem with the left ventricle. However, reduced function of the right ventricle can also occur in heart failure. As blood begins to back up behind the failing left ventricle and into the lungs, it will become increasingly difficult for the right ventricle to pump returning blood through the lungs. Like the left ventricle, the right ventricle will eventually weaken and begin to fail. While left-sided heart failure is typically the cause of right-sided heart failure, other conditions, such as certain lung diseases, can cause the right ventricle to fail even when there is no problem with your left ventricle.
People with heart failure can have more than one type of heart failure. For example, left-sided heart failure can cause right-sided heart failure. In such cases, heart failure does not have more than one cause, but rather the heart failure is affecting the heart in more than one way. In other cases, there may be two separate problems, such as mitral regurgitation causing left-sided heart failure but tricuspid regurgitation causing right-sided heart failure.
How can systolic dysfunction cause heart failure? A low ejection fraction is the hallmark of systolic heart failure. Determining your ejection fraction is essential for effectively diagnosing and treating your heart failure. Systolic dysfunction means that your heart is not functioning well during systole, the phase of your heartbeat when your heart squeezes (contracts) and pumps blood.
You may develop systolic dysfunction when another serious condition, such as coronary artery disease, damages your heart. As your body attempts to compensate for your systolic dysfunction, your heart may be damaged further, leading to more severe dysfunction and ultimately to heart failure. Systolic dysfunction most commonly affects the left ventricle, the chamber of your heart that pumps blood out to your body, but it can also affect your right ventricle.
What is my ejection fraction?Your ejection fraction measures how efficiently your left ventricle is pumping blood. During diastole, the phase of the heartbeat between contractions, your left ventricle fills with a certain amount of blood. During systole, the ventricle contracts and pumps a certain portion of that blood out to your body. Your ejection fraction is the percentage of the blood that fills your left ventricle during diastole that is then pumped out to the body during systole.
In a healthy heart, the ejection fraction is more than 55%. In systolic heart failure, the ejection fraction is less than normal, and it can be as low as 10% to 15%. If you have systolic heart failure, the volume of blood pumped with each heartbeat (the stroke volume) is reduced in addition to the percentage of blood that is pumped with each heartbeat (the ejection fraction).
How does my heart compensate for systolic dysfunction? Your heart may be able to compensate for systolic heart failure by getting more blood into your ventricle. Unfortunately, this effort to compensate for systolic dysfunction by left ventricular dilatation can damage your heart further, leading to more severe dysfunction. If your ejection fraction drops below 40% to 50%, doctors will consider you to have systolic dysfunction. While you can have a low ejection fraction without developing heart failure, the more systolic dysfunction you have, the more likely you are to develop heart failure.
How can diastolic dysfunction cause heart failure? Diastole is the phase of your heartbeat when your heart relaxes and fills with blood. Diastolic dysfunction means that your left ventricle cannot relax properly during diastole. As a result, your ventricle does not fill with enough blood before it pumps. If diastolic dysfunction is severe enough, it can lead to heart failure.
Diastolic heart failure happens because the left ventricle's muscle becomes too stiff or thickened. To compensate for stiff heart muscle, your heart has to increase the pressure inside the ventricle to properly fill the ventricle. Over time, this increased filling causes blood to build up inside the left atrium and eventually into the lungs, which leads to fluid congestion and the symptoms of heart failure.
Why doesn't diastolic heart failure affect my ejection fraction?In diastolic heart failure, your left ventricle may pump well during systole; it is just not filling with enough blood during diastole. Your ventricle may have a normal ejection fraction, but it has less blood inside it to pump out. As a result, your ventricle pumps out less blood with each beat (what doctors call a decrease in stroke volume).