Blood pressure is measured by two numbers: systolic and diastolic. The systolic pressure reflects the force of blood against artery walls when your heart beats. The diastolic pressure measures the pressure in your arteries when the heart rests between beats. While high blood pressure is a well-known concern, a low diastolic reading can also have important health implications. This article explains what a low diastolic reading signifies, explores the contributing factors, and outlines the associated symptoms and necessary management steps.
Defining Low Diastolic Blood Pressure
Diastolic pressure represents the minimum pressure exerted on the arteries during the period when the heart is refilling with blood. This resting phase is important because it is when the heart muscle receives its own supply of oxygenated blood through the coronary arteries. If this pressure is too low, the heart muscle may not receive sufficient blood flow. A diastolic reading of 60 millimeters of mercury (mmHg) or lower is generally considered the clinical threshold for low blood pressure, or hypotension. When the diastolic pressure is below 60 mmHg but the systolic pressure remains normal, the condition is termed isolated diastolic hypotension. This condition is concerning because it can compromise the blood supply to the heart muscle, potentially leading to long-term weakening.
Factors Contributing to a Low Diastolic Reading
A common cause for a low diastolic reading is the natural stiffening of arteries that occurs with age. As artery walls lose elasticity, they cannot recoil effectively between heartbeats. This causes the diastolic pressure to drop while the systolic pressure may increase, widening the pulse pressure.
Medications
Certain medications are also frequently responsible for lowering the diastolic number. Drugs that cause vasodilation, or the widening of blood vessels, such as alpha-blockers used for hypertension, can lower diastolic pressure more significantly than systolic pressure. Other medications, including diuretics, some antidepressants, and drugs for Parkinson’s disease, can also contribute to a drop in blood pressure.
Acute Conditions and Underlying Issues
Acute, temporary conditions can also cause a drop in diastolic pressure. Severe dehydration reduces overall blood volume, resulting in lower pressure in the arteries. More serious underlying medical issues, such as severe anemia, heart valve problems like aortic regurgitation, or systemic infections like sepsis, can significantly impair the body’s ability to maintain adequate diastolic pressure. Endocrine disorders, such as adrenal insufficiency, may also play a role by affecting the tone of the blood vessels.
Associated Symptoms and Guidance for Next Steps
When diastolic pressure is too low, the body may not receive sufficient blood flow, leading to various noticeable symptoms. Common signs include feeling lightheaded or dizzy, particularly when moving from sitting or lying to standing (orthostatic hypotension). People may also experience fatigue, blurred vision, and occasional fainting (syncope).
Because low diastolic pressure can reduce blood flow to the heart, some individuals may experience symptoms that mimic heart issues, such as chest discomfort or heart palpitations. In older adults, low diastolic pressure is a safety concern as it can increase the risk of falls due to dizziness. If you are experiencing these symptoms, or if your blood pressure reading is consistently below 90/60 mmHg, consult a healthcare professional.
Immediate medical attention is necessary if a low diastolic reading is accompanied by severe symptoms like sudden, profound dizziness, confusion, or sharp chest pain. For less severe instances, a doctor can help determine the underlying cause and adjust any contributing medications.
Lifestyle adjustments can often help manage the condition. These include increasing fluid intake to boost blood volume and carefully adjusting dietary salt consumption as advised by a physician. A doctor may also recommend wearing compression stockings to help prevent blood from pooling in the legs or making changes to how quickly you stand up. Regular monitoring of blood pressure is important, especially for those with existing heart conditions. Maintaining a diastolic pressure above 60 to 70 mmHg is generally recommended to ensure adequate blood flow to the heart muscle.