Heart failure is a chronic condition where the heart struggles to pump blood effectively throughout the body. This means the body’s organs and tissues may not receive enough oxygen and nutrients to function properly. There are different classifications of heart failure, depending on how the heart’s pumping ability is affected.
Understanding Heart Function: Systole and Diastole
The heart operates in a continuous cycle of contraction and relaxation to circulate blood. These two primary phases are known as systole and diastole. Systole is the contraction phase, when the heart muscle squeezes to push blood out into the arteries and throughout the body. Following contraction, the heart enters diastole, which is its relaxation phase. During diastole, the heart chambers refill with blood returning from the body and lungs, preparing for the next beat.
Ejection Fraction: A Key Measurement
Ejection fraction (EF) is a measurement that indicates how efficiently the heart pumps blood with each beat. Specifically, it measures the percentage of blood pumped out of the left ventricle, the heart’s main pumping chamber, with each contraction. EF is typically measured using an echocardiogram, a common imaging test. A healthy ejection fraction usually falls within the range of 50% to 70%. A “reduced” ejection fraction means the heart is not pumping out as much blood as it should.
Heart Failure with Reduced Ejection Fraction (HFrEF)
Heart Failure with Reduced Ejection Fraction, or HFrEF, is a specific type of heart failure. It is diagnosed when the left ventricle, the heart’s primary pumping chamber, has a weakened ability to contract and eject blood. This weakened squeezing action results in a reduced amount of blood being pumped out to the body. The diagnostic threshold for HFrEF is typically an ejection fraction of 40% or less. This condition signifies that the heart muscle itself is not strong enough to effectively pump blood forward.
HFrEF: A Form of Systolic Heart Failure
HFrEF is classified as a form of systolic heart failure. The reason for this classification lies in the fundamental problem: the heart’s impaired systolic function. This means that during the systole phase, the heart cannot squeeze forcefully enough to push a sufficient volume of blood out to meet the body’s demands. In contrast, diastolic heart failure involves issues with the heart’s relaxation and filling phase, rather than its contraction. HFrEF is characterized by a loss of cardiomyocytes, leading to a decreased ability of the left ventricle to contract properly.
The Impact of Reduced Pumping Ability
When the heart’s ability to pump blood is significantly reduced, as seen in HFrEF, the body’s organs and tissues do not receive adequate oxygen and nutrients, leading to a range of noticeable symptoms. Individuals may experience fatigue and general weakness, especially during physical activity, because their muscles are not getting enough oxygenated blood. Fluid retention is another common consequence, often manifesting as swelling in the legs, ankles, and feet, and sometimes in the abdomen. This occurs as blood can back up due to the heart’s inability to efficiently move it forward. Shortness of breath, particularly with exertion or when lying flat, can also develop as fluid accumulates in the lungs.