Diastolic heart failure (DHF) is a condition where the heart muscle, specifically the left ventricle, becomes stiff and less able to relax fully between beats. This inability to properly fill with blood during the resting phase, called diastole, causes blood to back up into the lungs and body. The condition is formally known as Heart Failure with Preserved Ejection Fraction (HFpEF) because the heart’s pumping strength, or Ejection Fraction (EF), remains normal, which complicates the diagnosis. Doctors must look for evidence of impaired relaxation and increased pressure inside the heart chamber to confirm DHF.
Recognizing the Initial Signs
The diagnostic process begins with reviewing the patient’s medical history and current physical symptoms. Patients often report common heart failure symptoms like fatigue and shortness of breath, particularly during physical activity or when lying flat (orthopnea). They may also notice swelling (edema) in their ankles, legs, or abdomen due to fluid retention.
Several pre-existing conditions are linked to DHF, including long-standing high blood pressure, diabetes, and obesity. Identifying these conditions helps establish a high clinical suspicion for the disease. During the physical examination, the physician looks for signs of fluid congestion, such as crackling sounds in the lungs (rales or crackles), which indicate pulmonary congestion.
Another important finding is Jugular Venous Distention (JVD), a visible bulging of the neck veins, signaling elevated pressure in the right side of the heart. The presence of these physical signs, coupled with the patient’s symptoms and risk factors, suggests a clinical syndrome of heart failure. These initial findings direct the subsequent, more specialized diagnostic procedures needed to confirm diastolic dysfunction.
The Essential Role of Echocardiography
Echocardiography, an ultrasound of the heart, is the most important tool for establishing a DHF diagnosis. This non-invasive test uses sound waves to create moving images, allowing doctors to assess the heart’s structure, function, and blood flow. The defining characteristic of DHF is confirmed through this imaging: the Left Ventricular Ejection Fraction (LVEF) is greater than 50%, meaning systolic pumping action is preserved.
Since the EF is normal, the focus shifts to measurements revealing impaired relaxation and increased pressure within the left ventricle during filling. One key measurement is the E/A ratio, which compares the velocity of early rapid filling (E wave) to the filling contributed by atrial contraction (A wave). A reduced E/A ratio can suggest impaired relaxation, often the mildest form of diastolic dysfunction.
More telling is the Tissue Doppler Imaging (TDI) measurement, which assesses the velocity of the heart muscle movement, specifically the early diastolic velocity (e’ wave). This e’ wave is reduced in DHF patients because the stiff heart muscle cannot relax quickly. The E/e’ ratio, which combines the mitral inflow E wave with the myocardial e’ wave, reliably estimates left ventricular filling pressure. An average E/e’ ratio greater than 14 strongly suggests elevated filling pressures, a hallmark of DHF.
The echocardiogram also provides crucial information on the Left Atrial (LA) size, which often becomes enlarged due to chronic high pressure backing up from the stiff left ventricle. A Left Atrial Volume Index (LAVI) greater than 34 mL/m² is a major criterion for diastolic dysfunction. Additionally, the velocity of blood flow regurgitating through the tricuspid valve (TR velocity) helps estimate pulmonary artery pressure; a TR velocity greater than 2.8 m/s supports the diagnosis of elevated heart pressures.
Supporting Diagnostic Markers and Tests
While echocardiography is central, other tests provide supportive evidence of cardiac stress and fluid overload. Blood tests for B-type Natriuretic Peptide (BNP) or its precursor, N-terminal pro-B-type Natriuretic Peptide (NT-proBNP), are frequently used. These neurohormones are released by the heart muscle in response to excessive stretching or wall stress caused by high internal pressures.
Elevated levels of NT-proBNP suggest the patient’s symptoms are due to a cardiac cause, even if the heart’s pumping action is normal. A significantly high NT-proBNP level provides strong evidence of increased left ventricular filling pressure, correlating with the severity of diastolic dysfunction. However, in mild DHF, natriuretic peptide levels can be normal, so a low result does not definitively rule out the condition.
An Electrocardiogram (ECG) is useful for identifying associated electrical issues, such as atrial fibrillation, which is common in DHF patients and can worsen symptoms. The ECG may also show signs of left ventricular hypertrophy, or thickening of the heart muscle, a structural change that contributes to the heart’s stiffness.
A Chest X-ray (CXR) is performed to look for signs of pulmonary congestion, which appears as fluid in the lungs. This offers visual confirmation of the fluid backup that causes breathlessness. While neither the ECG nor the CXR can definitively diagnose DHF, they help build a comprehensive picture of the patient’s cardiac health.
Synthesizing the Data: Diagnostic Scoring Systems
Due to the complex nature of diastolic heart failure, the final diagnosis is rarely based on a single test result but on a combination of clinical factors and objective measurements. Clinicians use structured algorithms, or scoring systems, to synthesize available data and determine the probability of the patient having HFpEF. These systems are necessary because the diagnosis can be ambiguous, particularly in patients presenting with non-specific symptoms like breathlessness.
Two widely recognized scoring systems are the H2FPEF score and the HFA-PEFF score. The H2FPEF score assigns points based on clinical variables: high Body Mass Index (Heavy), Hypertension, Atrial Fibrillation, Pulmonary hypertension, age (Elderly), and the echocardiographic E/e’ ratio (Filling pressure). A patient’s total score is then used to classify the probability of having HFpEF as low, intermediate, or high.
The HFA-PEFF score is a comprehensive, step-wise algorithm incorporating pre-test assessment, echocardiographic and natriuretic peptide results, and, if needed, functional testing. These systems guide the physician, ensuring that both clinical presentation and objective evidence of diastolic dysfunction are considered before confirmation. For patients with an intermediate probability score, the algorithm often recommends further specialized testing, such as exercise echocardiography, to unmask the condition under stress.