Dr Showkat Shah
Human body ,God’s supreme creation ,is the most efficient machine, beautifully engineered and constructed with the best materials with no planned obsolescence. Unlike other machines ,it is driven by the four chambered pump ,the Heart , the first organ to develop before the first breath and the brain. It pumps blood day and night without cessation until the individual dies .
The left portion of the heart has muscular powerhouse , left ventricle ,which builds the pressure we feel in the arteries as our pulse. Blood circulates in a closed circuit. Thanks to the English doctor and scientist William Harvey who discovered it only 360 years ago and today we know blood circulates and returns to the heart via the veins.
The heart as a pump with every beat (contraction) not only ejects blood but simultaneously also sucks in -this giving and taking is the heart’s most fundamental principle, the essence of love and balanced transformational rather than transactional relationship.
The heart is the mother and the well whose bloodstream supplies all cells with vital ingredients through the special conduit system , the arterial network .With every contraction of the heart, the moving column of the blood stretches the walls of these blood vessels connected to every single cell – the many thousands of billions of cells in our gut, genitals, arms, legs ,sensory organs and the supreme brain .The determinant of this force, the force that drives the life , per unit area is what we measure quantitatively as the blood pressure .Thanks to Stephen Hales (1677-1761) who eased out the trajectory to measure this ‘force of life’ and Dr. Nikolai Korotkoff (1874-1920), a Russian surgeon, who discovered the precise technique of measuring blood pressure using inflatable cuff (sphygmomanometer) !
Blood pressure is the measurement of pressure in our vessel conduits ,the arteries , during the active and resting phases of every heartbeat and the two numbers that we see on the meter are called systolic pressure (top number) and diastolic pressure (bottom number). Top number (Systolic) is the amount of pressure our heart generates when pumping blood throughout our body and bottom number (diastolic pressure) is the pressure in our arteries when our heart is at rest.
But the fact is that the heart never takes rest till we are alive !!
The doctrine of the lower , the better !
Sir William Osler’s words ,” It is much more important to know what sort of a patient has a disease than what sort of a disease a patient has”. Osler did not mention the risks of high BP in his classic ,‘The Principles and Practice of Medicine’ because, at that time ,the end of 19th century ,there was no practical way to measure BP using the simple inflatable cuff or so (noninvasive methods to measure BP ). Shortly after the development and dissemination of noninvasive methods for BP measurement ,physicians and actuaries deduced that high BP could be a cause of disease related to heart and vessels ,the cardiovascular system. This insight led us to adopt a blood pressure philosophy of “the lower, the better” and researchers have been chasing after the optimal blood pressure numbers the way Pythagoreans of old sought numeric answers for the riddles of the universe.
In the last 70 years the definition of normal blood pressure has seen a continuous downward revision. While the figure of 160/95mmHg was the upper limit of normal pressure in an adult in the 1960s but now even any figure above 120 /80 mm hg magical numbers haunt the sensitive brains to chase these mysterious figures to satisfy the feeling of being healthy !
Is lower always better ,the J-curve phenomenon
Although, there is no clear dividing line between normal blood pressure and low blood pressure, the question remains – How low is it alright for the blood pressure to go?
The 1970s decade-long study provided a clue that lowering blood pressure decreased the risk of death. But unexpectedly the risk increased again as the diastolic blood pressure (the second number, which is the pressure as the heart relaxes) fell below 85 millimeters of mercury, a pattern the study authors described as a ‘J-curve’ , the hypothesis introduced by Cruickshank in 1972. Subsequent studies have been mixed with some arguments in favour and others against the J-curve phenomenon for blood pressure. But a Landmark 2018 evidence-based study of more than 30,000 patients suggests that it does exist particularly in elderly and high risk patients with cardiac diseases .
The quest to find this sweet spot on the “J curve,” the point of intersection between maximum benefit and minimum risk, is still an enigma for all of us!
Low blood Pressure, myth vs fact !!
While it is clearly documented in medical literature as to who will fall under the high blood pressure category, there is no such quantification for low blood pressure. It can vary from individual to individual. Low blood pressure has immense importance to no importance. An incidental finding of low blood pressure may ideally not be a cause of worry. But as a general rule, if a patient has no symptoms or ill effects from low blood pressure digits then it’s probably normal for him . In fact, a low-ish blood pressure will greatly decrease the risk of heart disease, kidney failure and stroke. The lower limit for blood pressure is perhaps best defined by symptoms( like fatigue or dizziness ) rather than numbers. What’s considered low blood pressure for many may be normal for others.
In my cardiology practice , a lot of young people come to me with a BP of 90/60 or even lower who walk normally and perform their routine activities without any symptoms related to their low-ish blood pressure readings .Most of them are ambulatory and say “low pressure” because somebody (usually a relative or uninformed practitioner ) has taught them that “mild occasional dizziness is a symptom of low blood pressure”. In despair and fear they knock the doors of internists and complain of having suffered some dizziness a few moments ago .Such mild occasional short-lasting dizziness is common during periods of mental stress. Most of these patients have generalized anxiety disorders or stress-induced panic disorders of some intensity, and these poor chaps are never enlightened about this by most doctors and given unnecessary formulations only to end up with their myriad side effects .
I examine them and check their blood pressure in three positions — lying, sitting and standing. If there isn’t much of a drop in standing position, I reassure the patient that blood vessels are working normally and the set of the digits of blood pressure is probably normal for you . But if blood pressure drops more than 20 to 30 points on standing , the condition is called Orthostatic hypotension and is as a result of dysfunctional auto-regulatory equilibrium mechanism (homeostasis ).This needs further Clinical work up by an experienced internist /cardiologist .
Orthostatic hypotension has several causes. A common one stems from taking fluid pills(diuretics), especially in aged people. These diuretic pills decrease the amount of fluid in the circulation and when the person stands there isn’t enough fluid in the bloodstream to maintain blood pressure in a normal range.The symptoms include dizziness, lightheadedness, feeling faint or sensation of black-out or falling after standing. But these episodes usually are infrequent and pass quickly.
However, some people have severe orthostatic hypotension that doesn’t readily clear up. Their blood pressure can plummet, stay down and lead to debilitating symptoms. Besides fluid pills, other causes of low blood pressure (hypotension ) include certain neurological disorders ,diabetes ,low haemoglobin(anemia),dehydration or as a result of certain medications for different disorders(antidepressants etc) .Blood pressure in some elderly individuals tends to temporarily decline shortly after eating , a condition called postprandial hypotension, a deregulated mechanism of ‘biological equilibrium’ (Homeostasis ).
These asymptomatic patients with low BP without any underlying disorder need preemptive ‘Reassurance ‘. In my clinical practice, I prefer cognitive rather than affective reassurance .This allays their long term anxieties about chronic low BP readings and reinforces the sense of physical and psychological well-being .
To conclude , neo-Pythagoreans will remain relentless in their quantitative pursuits. But answers to the riddle of ‘the lower the better ‘will not come from biostatistics, or spreadsheets but from examining patients, lest we go on treating them “by the numbers, for the numbers”.
Dr Showkat Hussain Shah consultant cardiologist GMC Anantnag and can be reached at shahmed25@gmail.com