What is happening your body if your blood pressure changes on a daily basis?

This study looked at stroke patients with high blood pressure and investigated whether variations in their blood pressure is associated with their body reacting differently during tasks and stimuli.

A stroke occurs when there is a disturbance of oxygen supply to a part of the brain. Most of the time this is caused by a blood clot, called an ischemic stroke. High blood pressure is when pressure inside blood vessels is too high. Stroke patients may develop temporary high blood pressure, which puts them at high risk of having another stroke.

A person’s blood pressure can vary greatly every hour, day, or between clinic visits. However, it is thought that changes in daily systolic blood pressure (SBP), which is the pressure when the heart is contracted, may increase the risk of recurrent stroke. The reason for this is unknown.

This study investigated whether the way in which a stroke patient’s blood pressure varies is associated with their bodies reacting differently to a number of different tasks and stimuli.

A total of 223 patients who previously had an ischemic stroke or ministroke within the last 6 weeks were included in the study. To investigate blood pressure variability, blood pressure was monitored in three different ways:

1. Home blood pressure was measured by the patients at home which involved measuring it 3 times at one sitting, 3 times a day (morning, noon, and evening), for 1 month.
2. 24-hour ambulatory blood pressure which involved measuring pressure every 30 minutes during the day and every 60 minutes at night for 24 hours.
3. Blood pressure measured continuously for 5 minutes (called beat-to-beat pressure) in the clinic by a health professional for two-sittings at 1 month apart.

Patients were asked to perform different tasks; such as a subtracting numbers in their head, immersing their hand into iced water, or standing up quickly after lying down. The investigators then set out to see if elevations in blood pressure and heart rate experienced during these tasks were associated with their history of blood pressure variability. 

The study found that variations in beat-to-beat SBP and home SBP were associated with high blood pressure and greater heart rate variability during the tasks. 

The authors suggest that patients who have variable SBP experience more body stress and changes during mental and physical tasks, and this may explain why SBP variability is associated with a higher stroke risk. 

The study did not measure any correlation between SBP variability and occurrence of stroke, it only made a connection between SBP variability and changes in blood pressure and heart rate during mental and physical tasks. 

If you or someone you know have recently had a stroke and have high blood pressure, talk to a doctor about daily home blood pressure monitoring to check if your blood pressure is under control.