It’s an established fact that high blood pressure (BP) is detrimental to health, but how about spikes in blood pressure?
For Life speaks to Professor Kazuomi Kario of Japan’s Jichi Medical University who was at the 13th Asia-Pacific Congress of Hypertension in Singapore to present new research suggesting that those with high morning surge BP are at 2.7 times higher risk of stroke events than those with stable hypertension.
(Q) How can surges of BP in the morning and fluctuations in BP throughout the day contribute to cardiac incidents?
(A) People with high BP, also known as hypertension are more likely to develop coronary artery disease, because high blood BP puts added force against the artery walls. Over time, this extra pressure can damage the arteries, making them more vulnerable to the narrowing and plaque build-up associated with atherosclerosis.
Surges and exaggerated fluctuations in BP 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. The broken off pieces of plaque can then travel through the circulatory system and cause blockages in smaller blood vessels that can, depending on where they lodge, cause strokes or damage the heart and/ or kidneys.
(Q) What puts a patient at risk of having surges of BP in the morning?
(A) Our BP follows a circadian rhythm. It typically dips slightly during the night while we sleep, peaking shortly after we wake and then settling to its normal range during the course of the day with slight dips and rises in line with our activity levels, meals etc.
Most hypertension patients follow a similar circadian rhythm but in some it is more exaggerated and their nocturnal (nighttime) BP drops dramatically to be more than 20% of their normal baseline diurnal (daytime) BP. We call those dippers. Dippers often have an equally exaggerated morning surge. Any morning surge can increase the risk of cardiovascular (CV) events but the bigger the fluctuation between dip and surge the more dangerous it is.
Things that can put people at more risk of morning BP surge include eating salty evening meals, smoking, long term over-consumption of alcohol, stress, obesity, sleep-apnoea, diabetes, and chronic kidney disease.
(Q) Why are Asians predisposed to having surges of BP in the morning?
(A) There are probably several factors and this area definitely requires more research to identify all of them but one cause we do know about is that many Asians are genetically more sensitive to salt due to a variation in the renin–angiotensin–aldosterone system (RAAS), a hormone system that is involved in the regulation of the plasma sodium concentration and arterial BP. As well as being more sensitive to salt many Asians consume a lot of salt because of the heavy use of soy and other sauces in Asian cuisines.
Other factors could be the rising incidence of obesity and the fact that many urban dwelling Asians report very high stress levels.
(Q) What can one do to prevent cardiac incidents such as stroke from happening?
(A) If you have already been diagnosed with hypertension then you should follow your physician’s advice about diet, exercise and most importantly take your prescribed medication. Avoid salty foods, don’t smoke, moderate or stop the consumption of alcohol, try to maintain a healthy weight, and stay active even if it is only a few short walks a day.
The same advice goes for everyone whether they have been diagnosed with hypertension or not but if you or your doctor think you might be at risk of hypertension but your BP readings are normal when you are checked in a clinical setting, you should consider monitoring your BP at home in case you have what we call masked hypertension. Masked hypertension is when a patient has normal BP in the clinic but high BP out of the clinic.
This can mean that hypertension is often not picked up during visits to healthcare facilities. It may occur because BP 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 even have been asked to fast which can also temporarily lower BP.
Some patients are the opposite. When they visit the clinic their BP is high but at other times and in other locations it is in normal. We call this the white coat effect and it is probably caused be stress. If the patient is worried about seeing the doctor or finds the very process of having their BP checked stressful it can ironically cause a temporary spike in BP.
(Q) How can measuring and keeping a record of BP help prevent cardiac incidents?
(A) Morning surges in BP and also large fluctuations in BP during the course of the circadian cycle are a strong indicator of risk of cardiovascular events in general or what we call target organ damage involving the brain, heart and/or kidneys. Regular home monitoring allows the doctor to see if a patient is exhibiting any of the warning signs such as morning surges or large fluctuations that might indicate they are at increased risk. Patients with high morning surge BP are at 2.7 times higher risk of stroke events than those with stable hypertension. Home monitoring can even identify masked hypertension that has not previously been identified in the clinic.
