Chronic congestive heart failure (CHF) occurs when the heart cannot circulate blood effectively to meet the body’s needs. This diagnosis is categorized by which phase of the cardiac cycle is compromised: pumping or filling. This article focuses on the latter, historically known as chronic diastolic heart failure. Clinically, this condition is most often referred to as Heart Failure with Preserved Ejection Fraction (HFpEF), because the heart’s primary pumping function remains within a normal range.
The Mechanism of Impaired Filling
The fundamental defect in HFpEF occurs during the diastole phase, when the heart muscle relaxes and the ventricles fill with blood. In a healthy heart, the muscular left ventricle relaxes quickly and fully, creating suction that rapidly draws blood from the left atrium. This process requires the heart muscle to be flexible and compliant.
In HFpEF, the walls of the left ventricle become stiff, thickened, and less elastic over time. This structural change impairs the chamber’s ability to relax and accept incoming blood volume during diastole. Consequently, the ventricle cannot fill completely, reducing the overall stroke volume—the amount of blood pumped out—even though the heart muscle contracts with normal force.
Pumping strength is assessed by the ejection fraction (EF), the percentage of blood pumped out of the ventricle with each contraction. In HFpEF, the EF is preserved, typically measured at 50% or higher. The problem is the reduced volume of blood available to be ejected, leading to lower overall output. This impaired filling causes pressure to build up inside the left ventricle, subsequently backing up into the left atrium and the vessels leading from the lungs.
Recognizing the Physical Symptoms
The stiff left ventricle’s inability to accept blood volume causes a hydraulic backup, leading to physical symptoms. The most common complaint is dyspnea, or shortness of breath, which occurs because elevated pressure forces fluid to accumulate in the lungs. This shortness of breath is often exacerbated by physical activity, which increases the heart’s demand for filling.
Many individuals also experience orthopnea, which is difficulty breathing when lying flat. When supine, fluid redistributes from the lower extremities to the central circulation, overwhelming the stiff heart and intensifying lung congestion. Chronic fatigue and a reduced capacity for exercise are common symptoms, resulting from the heart’s failure to sufficiently increase output to supply oxygen to working muscles during exertion.
Fluid retention, medically termed edema, frequently appears in the lower extremities, such as the ankles and legs. This peripheral swelling results from high pressures in the veins, a consequence of blood backing up from the right side of the heart attempting to empty into the congested left side. These symptoms reflect the systemic congestion that defines the condition.
Underlying Causes and Risk Factors
The primary conditions leading to heart muscle stiffening are those that place a chronic, excessive workload on the organ. Long-standing, poorly controlled hypertension is the single most significant risk factor, present in over 80% of HFpEF patients. To pump blood against persistently high resistance, the heart muscle thickens (concentric hypertrophy), which directly causes the loss of elasticity necessary for proper relaxation.
Other metabolic and cardiovascular conditions frequently co-exist and contribute to this syndrome. Advanced age is an independent risk factor, as the heart muscle naturally stiffens and loses compliance over time. Diabetes mellitus and obesity are also strongly associated with HFpEF, likely by promoting systemic inflammation and changes in heart muscle structure.
Coronary artery disease, which reduces blood flow to the heart muscle, contributes by impairing the heart’s energy-dependent relaxation process. These chronic conditions work in concert, gradually altering the ventricular wall structure until the heart’s filling ability is compromised.
Treatment Approaches and Lifestyle Adjustments
Management of chronic diastolic heart failure centers on addressing the underlying causes of stiffening and controlling fluid overload. Aggressive management of high blood pressure is paramount, often requiring multiple anti-hypertensive medications to lower resistance. Similarly, tight control of blood sugar levels is a major focus for patients with co-existing diabetes.
Diuretics, commonly known as water pills, are the mainstay for symptom relief, reducing the excess fluid volume that causes congestion and peripheral edema. Careful fluid management is required, however, because excessive volume reduction can lead to a drop in cardiac output in a heart that already struggles to fill.
Unlike systolic heart failure, historically fewer medications were proven to alter the disease course or prolong survival in HFpEF. However, recent clinical trials show promise for certain drug classes, notably SGLT2 inhibitors and mineralocorticoid receptor antagonists, which reduce heart failure hospitalizations. Lifestyle adjustments are equally important for managing the condition and improving quality of life. Patients are advised to restrict sodium intake to reduce fluid retention and monitor fluid consumption. Regular, moderate exercise is also recommended to improve physical functioning and exercise tolerance.