Hypertension is the most common cardiovascular risk factor worldwide, affecting one third of the global population. The current definition of hypertension as a blood pressure over 140/90 mmHg measured during multiple clinic visits is insufficient because blood pressure is a continuously changing variable that can be influenced by daily activities and stress. An updated definition is needed that incorporates measurements from home blood pressure monitoring and ambulatory blood pressure monitoring to better identify true hypertension versus transient high readings and better predict cardiovascular outcomes based on variability.

1. Do we need an updated Hypertension definition?
Jafar Al-Said, M.B.ChB. MD. FASN. FACP
Abstract:
Hypertension is the most common global cardiovascular risk factor. It affects one third of the
population worldwide and it carries a great burden on individual health as well as governmental
health expenditures. A properly measured clinic blood pressure more than 140/90mmHg is the
gold standard in diagnosis. Two or more blood pressure measurements during different clinic visits
are enough to confirm the diagnosis. However, it is well known that the BP is continuously
changing. How can we rely on only couple of reading spaced months apart to determine the
management? Is it required to update Hypertension definition with the current data?
Article:
Hypertension is the most common global cardiovascular risk factor. (1) It affects one third of the
population worldwide and it carries a great burden on individual health as well as governmental
health expenditures. (2,3) A properly measured clinic blood pressure more than 140/90mmHg is the
main diagnostic definition. Two or more blood pressure measurements during different clinic visits
are enough to confirm the diagnosis. (4,5) However, it is well known that the BP is continuously
changing. In fact, if we try to get 10 simultaneous measurements they rarely would be similar. It
also is well known that the Blood pressure changes during daily activities, with stress, during the
sleep cycle, and with exercise…Etc. (6) So, is it reasonable to use only the readings during 10-15
minutes of a clinic visit to draw a conclusion and put management plans for 2-3 months’ period?
It is more logical to anticipate that the clinic measurements are the odd reading among the whole
day BP rather than the representative reading. How could we completely rely on these
measurements to determine the whole treatment plans?
Going back to the basic pathophysiology of blood pressure we know that the systolic and diastolic
numbers are measured by occluding of a peripheral artery with a pressurized cuff. When gradually
deflating the cuff, the systolic pressure is represented by the Korotkoff’s first sound, with hearing
a bruit sound from the turbulent flow of blood through a partially occluded blood vessel. With
continuously deflating the cuff the sound will disappear when the blood flow become lamellar.
This will determine the diastolic BP. (6) This arterial pressure, whether systolic or diastolic, in any
given time, is determined by complex and continuous interactions between multiple variables
including:
1- Cardiac output.
2- Blood volume.
3- Blood viscosity.

2. 4- Central and peripheral vascular elasticity.
5- Total volume of the vascular bed. (7)
Each of these factors per say is regulated by different hemodynamic and neurohormonal cascades.
Simplifying all these interactions into a clinic BP reading, even if they are multiple, would
undermine the complete picture of Hypertension as a disease. A single clinic reading more than
140/90mmHg, no matter how carefully it is measured, would not represent more than the arterial
pressure at that given time. It will not give any indications on the pressure over the months between
clinic visits.
The evidence is accumulating from alternative Home and ABPM readings. (8) So, should these
readings be used to update the HTN definition instead? A new definition of Hypertension is
needed to cover this aspect as well as to differentiate a high pressure reading in a clinic from
Hypertension. The transient high BP measurement should not be identified as HTN. If the readings
were persistently elevated, beyond a cutoff 140/90mmHg, with a documented vascular disease or
signs of early target organ damage in the form of proteinuria, LVH, loss of vascular elastic tone or
retinopathy, then the disease is evident. The kidney, heart and brain are the major organs that are
affected and also play vital role in modulating the blood pressure levels through regulating
continuous neurohormonal cascades. Hypertension is a syndrome that affects all the vascular bed
secondary to persistent high blood pressure from the major vessels to the capillaries.
If we think about the current definition of Hypertension, having a blood pressure above
140/90mmHg within two or three different clinic visits, even in an ideal situation, this would only
mean that during that 15-30 minute of the clinic visit, it happened that all the hemodynamic and
neurohormonal factors has led to that specific number. It does not take in consideration the
variability that might happen out of the clinic during the regular daily life. Stress, long working
hours, alteration in mood, meals variation, and exercise which is part of the daily life could change
the numbers. Moreover, most of the patients are seen in clinics every 3 - 6 months
It is true that the current evidence, with the vast majority of research data, are linked to the clinic
blood pressure, the fact that the blood pressure is continuously alternating would require a second
thought and perhaps finding a better definition. Tracking clinic numbers should not be the ultimate
goal for diagnosis or even management. There is an increasing evidence linking the BP variability
with cardiovascular outcome. It’s time to find a new measurement method that perhaps could
eliminate the variability and be more representative of CV risk. Home BP and ABPM, might be
utilized for updating the definition of Hypertension.

3. References:
1. World Health organization. Global Status Report on non-communicable diseases 2014.
http://www.who.int/nmh/publications/ncd-status-report-2014/en/
2. Chow CK1, Teo KK, Rangarajan S, Islam S, Gupta R, Avezum A, Bahonar A, Chifamba J,
Dagenais G, Diaz R, Kazmi K, Lanas F, Wei L, Lopez-Jaramillo P, Fanghong L, Ismail NH,
Puoane T, Rosengren A, Szuba A, Temizhan A, Wielgosz A, Yusuf R, Yusufali A, McKee M,
Liu L, Mony P, Yusuf S; PURE (Prospective Urban Rural Epidemiology) Study investigators.
Prevalence, awareness, treatment, and control of Hypertension in rural and urban Communities
in High, Middle and Low Income Countries. JAMA. 2013 Sep 4;310(9):959-68. doi:
10.1001/jama.2013.184182
3. Bromfield S, Muntner S. High blood pressure: The leading global burden of disease risk
factor and the need for world prevention program. Curr Hypertens Rep. 2013 June ; 15(3):
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4. Mancia G., Fagard R., Narkiewicz K. eta. The Task Force for the management of arterial
hypertension of the European Society of Hypertension (ESH) and of the European Society of
Cardiology (ESC) 2013 ESH/ESC. Guidelines for the management of arterial hypertension.
Journal of Hypertension 2013, 31:1281–1357.
5. Hypertension-European Society of Hypertension.
www.escardio.org/static_file/Escardio/Guidelines/publications/AHWeb_EM_Hypertension_
2013.pdf.
6. Beevers G, Lip G and O’Brien E. Blood pressure measurement Part I—Sphygmomanometry:
factors common to all techniques. BMJ. 2001 Apr 21; 322(7292): 981–985.
7. Dreibach , A. Pathophysiology of Hypertension.
http://emedicine.medscape.com/article/1937383-overview.
8. Hara A, Tanaka K, Ohkubo T, Kondo T, Kikuya M, Metoki H, Hashimoto T, Satoh M, Inoue
R, Asayama K, Obara T, Hirose T, Izumi S-I,Satoh H, Imai Y. Ambulatory versus home versus
clinic blood pressure: the association with subclinical cerebrovascular diseases: the Ohasama
study. Hypertension. 2012;59:22–28.