Left-sided heart failure
The heart's pumping action moves oxygen-rich blood from the lungs to the left atrium, then on to the left ventricle, which pumps the blood to the rest of the body. The left ventricle supplies most of the heart's pumping power, so it's larger than the other chambers and essential for normal function.
In left-sided or left ventricular heart failure, the left side must work harder to pump the same amount of blood. The percentage of blood the heart can pump with each beat is measured by a unit called ejection fraction, or EF. A normal left ventricle ejects about 55% to 60% of the blood in it.
There are two types of left-sided heart failure:
- Systolic failure: The left ventricle loses its ability to contract normally. The heart can't pump with enough force to push enough blood into circulation. This is also known as heart failure with reduced ejection, or HFrEF. When this occurs, the heart is pumping less than or equal to 40% EF.
- Diastolic failure: The left ventricle loses its ability to relax normally because the muscle has become stiff. The heart can't properly fill with blood during the resting period between each beat. This is also known as heart failure with preserved ejection, or HFpEF. When this occurs, the heart is pumping greater than or equal to 50%. EF heart failure with mid-range ejection fraction (HFmrEF) is a newer concept. In this type of heart failure, the left ventricle pumps between 41% and 49% EF. This places people with HFmrEF between the HFrEF and HFpEF groups.
Right-sided heart failure
The heart's pumping action moves "used" blood that no longer has oxygen in it back to the right atrium and on to the right ventricle. The right ventricle then pumps the blood back out of the heart and into the lungs to be replenished with oxygen.
Right-sided or right ventricular heart failure usually occurs as a result of left-sided failure. When the left ventricle fails and can’t pump enough blood out, increased fluid pressure is transferred back through the lungs. This damages the heart’s right side. When the right side loses pumping power, blood backs up in the body’s veins.
Congestive heart failure
Congestive heart failure, sometimes called CHF, requires quick medical attention. However, sometimes doctors use the terms congestive heart failure and heart failure interchangeably.
As blood flow out of the heart slows, blood returning to the heart through the veins backs up. This causes congestion in the body's tissues. Often swelling, known as edema, results. Most often there's swelling in the legs and ankles, but it can happen in other parts of the body, too.
Sometimes fluid collects in the lungs and interferes with breathing, causing shortness of breath, especially when a person is lying down. This is called pulmonary edema. If left untreated, pulmonary edema can cause respiratory distress.
Heart failure also affects the kidneys' ability to dispose of sodium and water. This results in more blood volume. This retained water also increases swelling in the body's tissues.