Normal Diastolic Range
In a healthy adult, the normal range for diastolic blood pressure is typically around 60 – 80 mmHg. This number reflects the lowest pressure within the arterial system during the cardiac cycle. It’s important because it provides an indication of the resistance in the blood vessels and the heart’s ability to refill with blood during relaxation.
When the heart contracts (systole), it pumps blood into the arteries, creating the systolic pressure. When it relaxes (diastole), the pressure drops as the heart fills with blood again. The diastolic pressure is maintained by the elastic recoil of the arteries and the peripheral resistance in the blood vessels.
Causes of a Low Diastolic Blood Pressure
Dehydration
One of the common causes of low diastolic blood pressure is dehydration. When the body is dehydrated, there is a reduction in blood volume. With less fluid in the bloodstream, the pressure exerted on the artery walls decreases. This can lead to a drop in both systolic and diastolic blood pressure, but the diastolic pressure may be particularly affected.
Dehydration can occur due to insufficient fluid intake, excessive sweating, vomiting, or diarrhea. For example, athletes who engage in strenuous exercise without proper hydration are at risk of dehydration and subsequent low blood pressure. In such cases, rehydrating the body can often help to restore blood pressure to normal levels.
Heart Conditions
Certain heart conditions can result in a low diastolic blood pressure. For instance, heart failure can lead to a weakened heart muscle that is unable to pump blood effectively. In diastolic heart failure, the heart has difficulty relaxing properly, which can cause the diastolic pressure to be lower than normal.
Another condition is bradycardia, a slow heart rate. When the heart beats too slowly, there is more time between beats for the blood pressure to drop during diastole. This can lead to a low diastolic reading. In some cases, heart valve problems can also disrupt the normal blood flow and pressure dynamics, resulting in low diastolic blood pressure.
Medications and Their Side Effects
Some medications can cause a decrease in diastolic blood pressure. Blood pressure – lowering drugs, such as certain types of antihypertensives, are designed to reduce overall blood pressure. However, in some individuals, they may cause the diastolic pressure to drop too low.
Other medications like diuretics can also lead to a reduction in blood volume, which in turn can lower the diastolic pressure. Additionally, medications used to treat erectile dysfunction can interact with nitrates and cause a significant drop in blood pressure, including the diastolic component.
Symptoms and Consequences of Low Diastolic Blood Pressure
Symptoms
Mildly low diastolic blood pressure may not cause any noticeable symptoms. However, as the pressure drops further, a person may experience dizziness, lightheadedness, or fainting. This occurs because the brain is not receiving an adequate supply of blood and oxygen.
Fatigue and weakness are also common symptoms. The body’s organs and tissues may not be getting enough blood flow to function optimally. Blurred vision can occur due to reduced blood supply to the eyes. In more severe cases, a person may experience shortness of breath as the heart tries to compensate for the low blood pressure.
Consequences for Organ Function
The kidneys are particularly sensitive to blood pressure changes. A low diastolic blood pressure can lead to reduced blood flow to the kidneys, which may affect their ability to filter waste products and maintain fluid and electrolyte balance. Over time, this can lead to kidney damage.
The heart may also be affected. In an attempt to maintain adequate blood flow, the heart may have to work harder. This can lead to an enlarged heart or other cardiac problems. Additionally, the brain’s function can be impaired due to insufficient blood supply, which can range from mild cognitive difficulties to more severe neurological problems in extreme cases.
When to Seek Medical Attention
Evaluating the Severity
If a person experiences a single episode of low diastolic blood pressure accompanied by mild symptoms like slight dizziness that resolves quickly, it may not be a cause for immediate concern. However, if the symptoms are persistent, severe, or accompanied by other signs such as chest pain, rapid heart rate, or confusion, medical attention should be sought immediately.
A sudden drop in diastolic blood pressure can be a sign of a more serious underlying condition, such as an internal bleed or a severe allergic reaction (anaphylaxis). In these cases, prompt medical treatment is essential to prevent further complications and potentially life – threatening situations.
Conclusion
A low bottom number (diastolic pressure) on a blood pressure reading can have various causes and implications. It’s important to consider the context, including any symptoms, underlying health conditions, and medications. While mild drops in diastolic blood pressure may be managed with simple measures like rehydration, more severe or persistent cases require medical evaluation and appropriate treatment to safeguard overall health and organ function.
Related topics：
What Does Diastolic Mean On Blood Pressure?
What Does “Dia” Mean in Blood Pressure?
What Is Normal Blood Pressure Bottom Number?
