Heart failure occurs when the heart struggles to pump enough blood to meet the body’s needs. Diastolic heart failure (DHF) is a specific form of this condition where the problem lies in the heart’s ability to relax and fill with blood between beats. This type of heart failure is clinically referred to as Heart Failure with Preserved Ejection Fraction (HFpEF).
The Mechanism of Diastolic Failure
The heart operates in a two-part cycle: systole, the pumping phase, and diastole, the filling phase. Diastolic heart failure occurs when the left ventricle, the heart’s main pumping chamber, becomes stiff and less compliant during diastole. This stiffness prevents the heart muscle from fully relaxing, making it difficult for the chamber to fill adequately with blood before the next beat.
The stiff ventricular walls resist the incoming blood, causing the pressure inside the heart chamber to rise significantly during filling. This elevated pressure backs up into the pulmonary veins, causing fluid to leak into the lungs. This results in symptoms like shortness of breath.
The heart’s ability to squeeze and pump the blood it receives, measured by the ejection fraction, often remains within the normal range. This preserved pumping strength means the condition is defined by the filling problem, despite the inadequate total volume of blood being moved to the body.
Distinguishing Diastolic from Systolic Failure
Heart failure is primarily classified based on whether the problem is with the heart’s pumping action or its filling action. Systolic heart failure, known as Heart Failure with Reduced Ejection Fraction (HFrEF), is fundamentally a pumping problem. In HFrEF, the heart muscle becomes weakened and stretched, leading to a diminished ability to contract forcefully.
This results in a low ejection fraction, meaning the heart cannot squeeze out a sufficient percentage of the blood it contains to circulate throughout the body. Conversely, diastolic failure (HFpEF) is a filling problem where the heart muscle is stiff but its ability to contract remains intact. While both conditions lead to insufficient blood flow and fluid backup, the underlying mechanical issue is distinct: a weak squeeze versus a stiff relaxation.
Underlying Conditions and Risk Factors
The primary cause leading to the stiffening of the heart muscle in diastolic failure is chronic, uncontrolled hypertension. When blood pressure is persistently elevated, the heart must work harder to push blood out against increased resistance. This prolonged strain causes the left ventricular muscle walls to thicken, a process called hypertrophy, which diminishes the muscle’s flexibility and relaxation capacity over time.
Aging is a significant risk factor, as the heart muscle naturally stiffens with advancing age. Other major contributing conditions include type 2 diabetes and obesity, which cause chronic inflammation that promotes stiffness. Chronic kidney disease is also linked to DHF, often due to associated hypertension and fluid imbalances.
Coronary artery disease, which can lead to ischemic episodes, can also impair the heart’s relaxation ability, contributing to the development of diastolic dysfunction.
Detection and Treatment Approaches
The primary tool used to diagnose diastolic heart failure is an echocardiogram, which uses sound waves to create images of the heart’s structure and function. This test measures the ejection fraction, which is preserved or normal in DHF, and reveals the thickened, stiff ventricles and signs of impaired relaxation.
Treatment for DHF focuses primarily on aggressively managing the underlying conditions that caused the heart to stiffen. This includes strict control of high blood pressure and diabetes, often involving diet and medication adjustments. To alleviate symptoms, diuretics are commonly prescribed to reduce fluid buildup and congestion.
Unlike systolic heart failure, which has established drug therapies to improve outcomes, DHF treatment relies heavily on controlling risk factors. Strategies include slowing the heart rate to allow more time for filling and reducing the overall strain on the stiffened heart muscle.