Having a condition characterized by low blood pressure and high heart rate (pulse rate) may be cause for concern, prompting a visit to your local physician. Tachycardia, also known as a high heart rate, is a term used to refer to a pulse rate greater than 100 beats per minute and may be a reflex when the body senses a fall in blood pressure. This is generally considered a normal transient physiologic response that occurs to help correct an abnormality in blood pressure.
However, there are pathological conditions causing low blood pressure and high heart rate, such as when the neural connections between the heart and the brain become dysfunctional, often leading to fainting spells. This condition, as well as others, should be assessed by a trained physician to find the underlying cause.
Causes of low blood pressure and high pulse rate
The human body relies on a balanced level of both blood pressure and heart rate, with both depending on each other to varying extents. The heart needs to pump blood between 80 to 100 beats per minute to ensure that organs and tissues are receiving appropriate perfusion. The heart rate can modify itself, as if it senses that a part of the body is not getting enough blood, it will begin to speed up, developing a heart rate over 100 beats per minute (tachycardia) to compensate.
While this a considered a normal phenomenon, there are instances where this can occur due to a secondary cause or be the result of a chronic disorder affecting the heart or the brain. The following are some origins of low blood pressure and high heart rate.
Neurally mediated hypotension (NMH): Due to faulty brain signals that fail to accurately recognize a state of low blood in the ventricle of the heart while standing. This condition often results in pooling of blood in the lower extremities and fainting (syncope).
Vasovagal syncope: Also referred to as vasodepressor syncope or neurocardiogenic syncope, this condition leads to a drop in blood pressure, which is quickly followed by a faster then slower heart rate. Because this leads to poor blood and oxygen flow to the brain, those affected often suffer from a temporary loss of consciousness.
Atrial fibrillation: Characterized by abnormal contractions of the atrial chambers of the heart, causing it to beat very quickly in relation to the lower ventricles. Because the ventricles do not have enough time to fill up normally, the amount of blood effectively pumped out of the heart is reduced.
Medication: Commonly used medication may cause the unwanted side effect of tachycardia and low blood pressure. These may include calcium channel blockers, diuretics, and various types of antidepressants.
Other causes include:
- Inflammatory processes
- Heart disease
- Weakening of the heart muscle
- Anaphylactic or traumatic shock
- Sudden decrease in body temperature
- Thyroid disorders
- Severe and moderate bleeding/blood loss
- Alcohol and nicotine abuse
Symptoms of low blood pressure and high pulse rate
Symptoms will mostly depend on the particular cause leading to low blood pressure and high pulse rate, but the following are some of the most common symptoms observed.
- Fainting (syncope)
- A sense of anxiety and fear
- General malaise (feeling of discomfort)
- Darkness under the eyes
- Pain behind the sternum
Diagnosis of low blood pressure and high pulse rate
A condition involving low blood pressure and high pulse rate is often transient in nature and not likely to be diagnosed during a routine doctor’s visit. However, if it is due to an underlying condition, it may be reproducible through testing or have certain markers that can be identified. The following are various testing modalities that help doctors reach a diagnosis.
- Blood testing: Can provide information about blood constituents, disease markers, and other abnormalities that can affect overall health.
- Electrocardiogram (ECG): Measures the electrical activity of the heart and can identify arrhythmia such as atrial fibrillation.
Echocardiogram: An imaging test that allows doctors to view the size, shape, and relative function of the heart.
- Cardiac stress test: With the use of a treadmill and ECG, the heart can be stressed to varying degrees, looking for changes in heart rate and blood pressure.
- Tilt table test: Allows for careful measurement of the heart rate and blood pressure in response to varying degrees of tilt while laying down on a table. It is often used to investigate the causes of repeated and unexplained fainting.
Treatment for low blood pressure and high pulse rate
Treatment will depend on your underlying cause, with most requiring their own unique form of therapy. For example, neurally mediated hypotension (NMH) is often treated with a combination of blood pressure medication and increased salt and water intake. However, this will not cure the condition, but rather help you manage it. Treatment for NMH will require persistence, commitment, and willingness to try several other drug and therapy combinations to help control the problem. Drugs known for improving NMH include fludrocortisone (Florinef), beta-blockers (atenolol), disopyramide (Norpace), fluoxetine (Prozac), sertraline (Zoloft), ephedrine, pseudoephedrine, theophylline, methylphenidate (Ritalin), and midodrine.
If your condition is benign and not due to any serious underlying problem, the following changes to your lifestyle may provide some help with low blood pressure.
- Staying hydrated will help to ensure your body has enough blood volume for the heart to pump. It is a good idea to limit alcohol intake, as it can make you become dehydrated.
- Compression socks are a great tool for preventing pooling blood in the lower extremities.
- Take your time to get up from a lying position by going slow. This will help prevent your body from working harder against gravity to pump blood to your head.
- Consume the daily recommended amount of salt as it helps to maintain adequate blood pressure levels. However, it is important not to consume excessive amounts.
- Seek medical attention right away if your symptoms are causing you excessive grief and discomfort.
Therapies employed to remedy cases of low blood pressure and high heart rate often do not cure the problem and should be managed with the guidance of an experienced physician. If you were to suddenly stop any prescribed treatment plans, symptoms may return or even worsen. It is important to recognize situations that may lead to symptom exacerbation and to avoid triggers. However, many of the conditions leading to low blood pressure and high pulse rate have not been extensively studied, with more research being required.