About a third of all adults across the world have high blood pressure values. The numbers are steadily rising, especially in Asia, where most people of the world live. You would know your blood pressure values, only when it gets measured. In fact, only half the people who have high blood pressure, know about it, as the other half never got it measured. Of those who know, less than half have it under control. Rise in blood pressure is overtly silent, but covertly damages our blood vessels, heart, brain, eyes and kidneys. By the time these damages happen, it is way too late to reverse.
Mahomed’s “high pressure diathesis”
For centuries physicians felt the pulse, and knew that in some it is weak, and in others it is hard or bounds. Chinese called it a “hard pulse disease”, and had some clue about its relation to salt and brain disease. In early 19th century English physician Richard Bright and others figured that individuals with dysfunctional kidneys had thickened blood vessels, and a well felt pulse.
Quite unrelated, but around the same time Dean Mohammad, one of the first Indian immigrants, had settled in England and had married an Irish lady. In 1874 his grandson, Frederick Akbar Mahomed, then a British physician created a sphygmograph. He obtained many blood pressure graphs and inferred that blood pressure can be elevated even without diseased kidneys. He called it “high pressure diathesis” and published his narrative in The Lancet, in the year 1879.
von Basch , Riva-Rocci and Korotkoff
Two years later in 1881 Samuel Siegfried Karl Ritter von Basch created a device to measure blood pressure. This device had a small metallic ball, that was to be placed on the wrist, over the pulse. One could measure the pressure that was necessary to obliterate the pulse. He called this device “sphygmomanometer” a scientific name for blood pressure meter we use till date.
In 1896, an Italian pediatrician Riva-Rocci created a new device. This device had a rubber cuff, worn around the arm. The cuff was to be inflated and the pressure at which the distal pulse over the wrist got obliterated, was the (systolic) blood pressure.
Later in 1905, a Russian Surgeon Nikolai Korotkoff, found that when the pressure from an inflated blood pressure cuff is released, one could also hear a sound of the pulse. This sound could be heard with help of a stethoscope, when placed over the vessel. This sound appeared at systolic pressure, and disappeared at a lower pressure. This lower pressure was diastolic blood pressure. Since then, blood pressure is two set of values. When we say it is 120/80, the higher value is systolic and the lower diastolic.
Harvey Cushing and Paul Dudley White
Harvey Cushing was a neurosurgeon. While on a casual visit to Italy in 1901, he met Riva-Rocci, and got inspired by looking at the blood pressure meter. When he reached back to US, he constructed a device, and started measuring blood pressure in his patients. In the process he discovered Cushing’s reflex – when pressure in the brain goes up, pulse rate slows down and blood pressure rises.
However, physicians and cardiologists were still unsure about blood pressure values. In 1937 an eminent US cardiologist Paul Dudley White, suggested that “Hypertension may be an important compensatory mechanism which should not be tampered with, even if we were certain that we could control it.”
To treat or not to treat
Till 1950s, indifference to high blood pressure values was such, that it was believed that values upto 200/100 mm Hg were not to be treated. In fact this level of blood pressure was called “benign”. In contrast higher blood pressure values that affected heart and kidneys, were termed as “malignant”. Malignant could be treated, but there were hardly any safe drugs available at that time. This indifference costed US president Roosevelt a fatal stroke, when he died while still in office in the year 1945.
After Roosevelt’s death, hypertension and heart diseases became a priority in the US. On June 16 1948, President Harry Truman signed ‘National Heart Act’ and established National Heart Lung and Blood Institute (NHLBI) in Bethesda. Iconic Framingham Heart study was launched in October same year. The first results came out in the year 1957, and established that hypertension (then defined as blood pressure more than 160/95 mm Hg) led to four times more heart attacks. Incidentally Dr Paul Dudley white was one of the strong supporters of this study.
Rustom Jal Vakil and first drug for hypertension
Rustom Jal Vakil (b1911) was a young doctor in 1938, when he had returned to India, after studying medicine at London. Around that time Indian pharmacologists RN Chopra and colleagues had reported on blood pressure lowering effects of Rauwolfia serpentina (Indian snakeroot, sarpagandha). While tablets made up of roots of this plant were available, and it was being used to treat heart diseases, its effects in humans was yet to be documented.
Vakil, in 1949, published in the British Heart Journal the 1st clinical trial report on R. serpentina therapy. In this paper, Vakil summarized 10 years of his experience with Rauwolfia and reported a clinical trial of this drug. This fired the imagination of the international research community and prompted isolation of Reserpine, a first effective medicine against hypertension. Vakil, however continued his clinical and research practice in cardiology in Bombay, and lived on till age of 63 in the year 1974.
More drugs to treat high blood pressure
In 1960, we had just three medicines to treat high blood pressure – reserpine, hydralazine and chlorthiazide. Benefits of lowering blood pressure were becoming quite apparent. The British physician James W. Black developed β-blockers in the early 1960s, and this was a next new class of medicines available to treat high blood pressure. James Black was awarded 1988 Nobel Prize for his discovery.
Beginning 1960s we had more blood pressure lowering medicines. These include calcium channel blockers, and in the next decade clonidine and alpha-methyl dopa. 1980s saw emergence of a new class of drugs ACE inhibitors and in 1990s angiotensin receptor blockers. Today we have about 100 molecules across 8 classes of blood pressure lowering drugs.
Risk factors for elevated blood pressure
By 1970s, the risk factors for hypertension were also apparent. Salt intake, tobacco, obesity and lack of physical activity were most prominent of them. In 1978, the world health day theme was “Down with high blood pressure” and many countries issued postage stamps to improve awareness about high blood pressure and its risk factors
Other risk factors such as high cholesterol levels, elevated lipid fractions, and inflammation got added to the list in 1980s and 1990s.
Blood pressure lowering goals – JNC reports 1977-2003
NHLBI in US had established a Joint National Committee (JNC) which over the years has given us blood pressure lowering goals. First JNC report in 1977 considered only the diastolic (or lower) value as the risk. It suggested that diastolic blood pressure should be less than 105mm Hg. Four years later, we realized that systolic (or upper blood pressure) is more or equally important.
Third JNC report in 1984 set the target to be less than 160mm Hg of systolic and less than 90 for diastolic blood pressure. Fifth JNC report in 1993 lowered the target to less than 140/90 mm Hg. Four years later, Sixth JNC report in 1997 suggested that individualized therapy can be considered in those with blood pressures between 130-139/80-89 mm Hg. Those with diabetes mellitus and early kidney disease were suggested a lower cut off. Seventh and last JNC report in the year 2003 lowered the targets to less than 130/90 in all, but less than 140/90 in elderly.
The current blood pressure guidelines
This was not really the last word on blood pressure goals. More research in 2015 showed that even lower goals help reduce risk of heart attacks and stroke in all age groups. By this time American Heart Association (AHA) had taken over hypertension guidelines. In 2017 it suggested less than 120/80 as normal, and less than 130/80 as the treatment goal. Not every one agrees with it. The values to look for are same in all age groups, less than 135/85 in European guidelines, and less than 140/90 in the world health organization guidelines.
Initially lowering blood pressure itself was a contentious issue. Today attempt to achieve a lower level is often debated. Over the years, as we have better and safe blood pressure lowering medications, it is possible to achieve what is “normal”. Yet, in some regions half the adult population is above this “normal”. Further, we need to take additional blood pressure lowering pill to achieve the desired values. Hopefully, in a few more years, we will come to agree a singular taget value.
Measuring blood pressure at or nearer home
As benefits of blood pressure lowering were evident, and large number of individuals need to be screened, hospitals not enough. Blood pressure measurement technology has now reached in the community and inside homes. In 2009, mercury blood pressure machines were banned in Europe. This is because mercury is toxic and its use had to be phased out. Initially spring loaded blood pressure machines emerged as an alternative.
In late 1970s, Donald Nunn and coworkers invented the first fully automated oscillometric BP cuff device. This technology was initially used in cardiac monitors, and later translated to office and onward to home measurements. Automated blood pressure device does not require a stethoscope to listen to the sounds.
It was observed for long that when blood pressure is higher when measured by doctors, or when measured in a hospital. This is called “White coat hypertension”. Need for better and more accurate values led to home or nearer-home values. Today digital and home measurements are becoming common.
World Hypertension Day
It was only in 2005, that we had our first “World Hypertension Day”. It is observed on 17th May every year, and was initiated by the World Hypertension league. The league currently comprised of 80 national hypertension societies.
Many challenges remain in hypertension management today. First is despite ease of diagnosis, most remain unaware. This can be met by better screening and awareness levels. Second is, once diagnosed individuals need to take medicines as well as adopt life style measures for life. Often there is a reluctance to initiate blood pressure lowering measures, as well as difficulty in adhering to life-long therapy. Fewer pills, two or more drugs in combination are some of the ways to improve adherence. Third, there is need to monitor and modulate therapies, that call for periodic blood pressure measurements. Home or nearer home monitoring is a key to mitigate this barrier.
So please get your blood pressure measured, and see how high are your values. You can relax if within the limits, and it can be safely and easily corrected if they are high. A stitch in time, saves nine.