Heart failure is a condition where the heart struggles to pump enough blood to meet the body’s needs. Acute diastolic heart failure specifically refers to a condition where the heart’s main pumping chamber, the left ventricle, becomes stiff and cannot properly relax and fill with blood. This acute onset can lead to a rapid accumulation of fluid in the lungs and other tissues, causing significant symptoms.
The Heart’s Diastolic Function
The heart operates in a continuous cycle of contraction and relaxation to pump blood throughout the body. During diastole, the relaxation phase, the heart’s lower chambers, particularly the left ventricle, fill with blood. This filling allows the ventricle to expand and prepare for the next beat. A healthy heart is elastic and compliant, increasing its volume without a significant rise in pressure.
In diastolic heart failure, the heart muscle stiffens and does not relax adequately. This impaired relaxation prevents the left ventricle from filling sufficiently with blood, even though its pumping ability (ejection fraction) may be preserved. The inadequate filling leads to increased pressure within the heart chambers, which can cause blood to back up into the lungs. This differs from systolic heart failure, where the heart muscle is weakened and cannot effectively pump blood out.
Causes and Acute Triggers
Diastolic dysfunction, the underlying issue in diastolic heart failure, often develops due to chronic conditions. High blood pressure is a common cause, as it forces the heart to work harder, leading to thickening and stiffening of the left ventricle. Other contributing factors include diabetes, coronary artery disease, and kidney disease, which can all negatively impact the heart muscle’s ability to relax. Aging also plays a significant role.
While chronic conditions set the stage, acute triggers can suddenly worsen stable diastolic dysfunction into acute heart failure. These acute precipitants include infections and irregular heart rhythms like atrial fibrillation, which can impair the heart’s filling time. Sudden increases in blood pressure, fluid overload, or a heart attack can also acutely stress the already stiff heart, leading to rapid decompensation. Non-compliance with medications or increased salt intake can also trigger an acute episode.
Identifying Symptoms and Diagnosis
During an acute episode of diastolic heart failure, symptoms often appear suddenly and can be severe. Patients experience shortness of breath, especially when lying flat, and fatigue. Fluid retention can lead to swelling in the legs, ankles, or abdomen. A persistent cough or wheezing may also be present due to fluid backing up into the lungs.
Diagnosis in an acute care setting involves a physical examination and specific tests. A doctor may observe signs of fluid overload. Blood tests, including B-type natriuretic peptide (BNP) levels, are used; elevated BNP levels typically indicate heart failure, though they do not distinguish between systolic and diastolic types.
An electrocardiogram (ECG) assesses the heart’s electrical activity, while a chest X-ray can show signs of fluid in the lungs. An echocardiogram, an ultrasound of the heart, evaluates the heart’s structure, how well it relaxes and fills, and its overall function. This imaging helps confirm diastolic dysfunction and differentiate it from other heart conditions.
Emergency Management and Treatment
Immediate management of acute diastolic heart failure focuses on stabilizing the patient and alleviating severe symptoms. A primary goal is to reduce fluid overload. Oxygen therapy is provided to improve breathing, and medications are administered to help the heart function more effectively.
Diuretics, often called “water pills,” are commonly used to remove excess fluid from the body, thereby reducing congestion in the lungs and periphery. Medications that help control blood pressure and heart rate are also administered, as high blood pressure and rapid heart rates can worsen diastolic filling. Beta-blockers, for example, can slow the heart rate, allowing more time for the heart to fill with blood. In some cases, nitrates may be used to improve blood flow and reduce the heart’s workload. Treatment also involves addressing the underlying acute triggers.