High Blood Pressure and its Dichotomy

“Under latest version of guidelines, published in 2003, the number of people classified as having medical condition – namely high BP – has increased by an estimated 50 million, further growing the potential markets for high blood pressure medications. And because the desired target for blood pressure are now so low, if you accept those guidelines many people need to be taking multiple medications to get their blood pressure down to target level”.[Moynihan and Cassels in Selling Sickness]

Defining BP: Florey the reputed comparative physiologist lamented on BP that it is one of the most difficult terms to comprehend. “While the blood is in motion”, Florey observes, “a large part of energy is kinetic. This energy can be recorded as blood pressure only when blood flow is obstructed…The measured pressure is an end pressure not to be confused with lateral pressure”. Whereas the definition from medical physiologist is “…..as the force or pressure which the blood exerts on the walls of blood vessel”.  So according to comparative physiologist it is end pressure and as per medical physiologist it is lateral pressure.

Oxford Handbook of clinical medicine (Ed: 2010) is blatantly blunt: “Blood pressure has a skewed normal distribution within the population….Therefore, it is impossible to define ‘hypertension’”. So we are faced with a question if we cannot define how can we refine?

End organ involvement a myth or reality? “The most common in the United States is hypertension, which affects 20% of the Americans over the age of 6 years. About 80% of the patients with hypertension have no evidence of end-organ involvement, which means that in the majority of cases of hypertension the presence of the disorder is based solely on the blood pressure measurement”.[Paul Merino The ICU Book 1988]

Some Facts worth pondering:

1.    Over 43 million adults in the United States have hypertension, but 31% are unaware of their elevated blood pressure;  17% are aware but untreated; 29% are being treated but have not controlled their blood pressure  (still > 140/90 mm Hg); and only 23% are well controlled. [Source Current Medical Diagnosis and Treatment]

2.    Mahatma Gandhi reportedly exhibited systolic pressure of 300 (it is well known he was averse to medicine) and some healthy peaceable may show a diastolic of 40 – 60mm Hg, both fully compatible with normality and health.

3.    Dividing line between Normotension and Hypertension: Authorities have differed on the dividing line ( See table below)

Year	Division	Author
1934	140/80	D. Ayman
1939	120/80	S.C Robinson and M. Brucer
1947	130/70	F.J.Browne
1946	160/100	P.Bechgaard
1948	140/90	G.A.Perera
1948	180/100	A.M. Burgess
1952	150/90	C.B.Thomas
1956	180/110	W.Evans

4. Cerebral Stroke and HBP: The relationship is not a linear one as evident from the Harrisons Prinicipal of Internal medicine 1998: "Although individuals with the most atherosclerosis are the ones most likely to have stroke, the co-relation is only approximate. Some patients with large infracts have minimum disease, and others have no ischemic symptoms but one or more major cerebral artery occlusions".

5. Treatment: A Times of India report (2nd Sept 2012) on the Cochrane Review says "that people with mild hypertension – a reading of 140/90 mm – should not be popping daily pills to control their condition" as "there have been no reduction in deaths, incidence of heart disease or stroke among 9,000 patients who have been taking medication for four to five years. ". Definately for cases with malignant hypertension needs to be treated but medication to the extent must be avoided and subsituted with exercise and diet.

[For details read "Revisiting Blood Pressure by Dr. Manu Kothari and Lopa Mehta, Bhalani Publishing House, Mumbai India]