Your blood pressure readings can tell a lot about your health. High blood pressure, or hypertension, can be a major sign of potential health problems. But, did you know that fluctuations in your blood pressure throughout the day can also be a red flag? Here, a cardiologist in Singapore, explains why – and what to do about it.
What are blood pressure readings for?
Blood pressure is the measurement of the force or pressure inside your arteries with each heartbeat.
When your doctor takes your blood pressure, it’s conveyed as a measurement with two numbers – one number on top and one on the bottom, like a fraction.
The top number refers to the amount of pressure in your arteries during the contraction of your heart muscle. The bottom number refers to the pressure when your heart muscle is between beats.
What is considered normal blood pressure? A reading that’s less than 120/80.
So, for a normal blood pressure reading, the top number needs to be between 90 and 120, and the bottom number needs to be between 60 and 80.
People with hypertension are more likely to develop coronary artery disease. This is because high blood pressure puts added force against the artery walls. Over time, this extra pressure can damage the arteries with plaque buildup that limits the flow of oxgyen-rich blood to your organs and other parts of the body. This is the underlying cause of most cardiovascular disease, explains cardiologist DR LESLIE LAM of The Cardiac Centre at Farrer Park Hospital.
Fluctuating blood pressure
Our bodies follow a circadian rhythm, which affects everything from sleep cycles and body temperature to appetite and metabolism. And, our blood pressure is no different.
“Our blood pressure typically dips slightly by 10 to 20 percent during the night while we sleep, peaks shortly after we wake up, and then settles in to its normal range during the course of the day, with slight dips and rises in line with our activity levels and meals,” says Dr Lam.
“Most people with hypertension follow a similar circadian rhythm. But, in some cases, it is more exaggerated and their nighttime blood pressure drops by much more than 20 percent of their normal daytime baseline. We call those ‘dippers’.”
Often times, dippers have an equally exaggerated morning surge.
There are certain things that can increase the risk of morning surges. These include:
- eating salty meals in the evening;
- long-term overconsumption of alcohol;
- sleep apnoea;
- chronic kidney disease
Why are fluctuations dangerous?
Surges and exaggerated fluctuations are dangerous because the changes in pressure on the walls of the blood vessels can loosen, and eventually break off pieces of the plaque built up on the blood vessels’ walls. These plaque pieces can then travel through the circulatory system and cause blockages in smaller blood vessels. These blockages can lead to stroke, or damage to the heart and kidneys, explains Dr Lam.
While fluctuating numbers aren’t always an indication of a bigger health problem, for some people, it can be a warning sign of future issues. Research has shown that major morning spikes in blood pressure and large fluctuations during the day are a strong marker of stroke and heart attack risk.
And, the bigger fluctuation between dip and surge, the more dangerous it is.
Here’s what you can do to reduce health risks
If you have already been diagnosed with hypertension, then you should follow your cardiologist or GP’s advice about diet, exercise and, most importantly, taking your prescribed medication, says Dr Lam.
“It’s also best to avoid salty foods, quit smoking, moderate or stop the consumption of alcohol, try to maintain a healthy weight, and stay active, even if it’s only a few short walks a day. Of course, the same advice goes for everyone, whether they’ve been diagnosed with hypertension or not.”
Monitor blood pressure at home
Also, Dr Lam says it is a good idea to buy a quality blood pressure monitor, and to get into the habit of checking your numbers in the mornings and evenings – even if your blood pressure is usually normal when your doctor takes it.
“Doing so can help catch what we call masked hypertension – when a patient has normal blood pressure in the clinic but high blood pressure readings outside of the clinic. This can mean that hypertension is often not picked up during visits to healthcare facilities,” he says.
“This may occur because blood pressure readings in clinics are done under ideal conditions. The patient is rested from sitting in the waiting room and, if the patient is having other tests done they may have been asked to fast, which can also temporarily lower numbers.”
Some patients are the opposite. Their numbers are high when they visit the clinic but, at other times and in other locations, their numbers are normal.
“We call this the ‘white coat effect’ and it’s likely caused by stress. If the patient is worried about seeing the doctor or finds the process stressful, it can ironically cause a temporary spike in numbers.”
Regular home monitoring, he says, can help to identify both of these anomalies in blood pressure readings.
Keeping a written record of your readings for a couple of weeks before your next checkup can be of further help to your doctor or cardiologist. He or she will be able to see if you’re exhibiting any of the warning signs such as large nighttime fluctuations or morning surges that might indicate you are at increased risk of stroke.
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