Do You Have a Good Blood Pressure (Part 2)

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June 25, 2003 | 36,094 views

Part2 of 3 [Part 1,Part 3]

Treating Numbers Instead of a Person

Authoritative advice for treating blood pressure has changed dramaticallyover the years. Forty years ago, the chapter on hypertension inHarrison's Textbook of Medicine stated:

"Whatever the form of therapy selected, it must not be forgottenthat the physician who treats hypertension is treating the patientas a whole, rather than the separate manifestations of a disease.The first principle of the therapy ofhypertension is the knowledge of when to treat and when not totreat... A woman who has tolerated her diastolic pressureof 120 for 10 years without symptoms or deterioration does notneed immediate treatment for hypertension. Marked elevation ofsystolic pressure, with little or no rise in diastolic, does notconstitute an indication for depressor therapy. This is particularlytrue in the elderly or arteriosclerotic patient, even though thediastolic pressure may also be moderately elevated."

Today, that would be grounds for malpractice. The chapter, whichwas written by John Merrill, a leading authority on hypertensionfrom Harvard, goes on to emphasize that:

"The physician must constantly weigh the value of makinghis patient 'blood pressure conscious' by a specific regimen andregular follow-up, against real need for any particular form oftherapy. Above all, in treatment or prognostication,he must avoid engendering in the patient a fear of the diseasewhich may be unwarranted in our present state of knowledge."

Contrast this with the current cookie cutter approach of treatingnumbers that are often meaningless instead of people. There is absolutelynothing new about prehypertension, which was previously referredto as "high normal" at levels higher than 120/80. Thiswould still be a preferable description since nobody knows whetherthese individuals will go on to develop sustained hypertension orare at any significantly increased risk for its complications.

All these new guidelines essentially accomplishare to convert 45 million healthy Americans into new patients bycreating fear. This is precisely what the experts emphasizedwe should take pains never to do! How could so many doctors havebeen so wrong for so many years?

Whatever happened to the Hippocratic dictumPrimum non nocere (First of all, do no harm)? It usedto be the primary concern of all doctors but seems to have now beensidelined or forgotten in the frenetic and impersonal pace of modernmedical practice. The recommendations in this new Seventh Reportof the Joint National Committee on Prevention, Detection, Evaluation,and Treatment of High Blood Pressure (JNC 7) are not very differentfrom the first JNC report. This was published on 1977 followingseveral studies showing that blood pressure could be lowered withthiazide diuretics. Subsequent JNC reports repeatedly recommendedthe use of diuretics as initial treatment based on additional reportsdemonstrating their efficacy.

Despite this, the use of diuretics actually declined over the nextdecade or so, possibly because many went off patent and were nolonger profitable. In addition, newer drugs were being vigorouslypromoted and the 1993 JNC 5 guidelines added angiotensin-convertingenzyme (ACE) inhibitors and beta blockers as first-line therapy.Their sponsors argued that these more expensive drugs might be preferablesince thiazide therapy could be associated with diabetes and abnormalheart rhythms, especially at higher doses. These medications hadother side effects but it was claimed that they were more likelyto reduce complications such as heart attacks and stroke.

However, many were not as effective even at higher doses or whencombined with other new anithypertensives. Specialists soon foundthat half of such patients with pressures greater than 160/100 ontwo or more of these drugs improved rapidly when diuretics wereadded or their dosage was increased. ACE inhibitors and beta blockerswere removed in JNC 6 and the new guidelines are about the sameas those proposed over 25 years ago, save for this new and confusingdiagnosis of prehypertension.

However, diuretics are not the most effective or safest treatmentfor all hypertensives and other drugs are clearly superior for certainpatients. What is wrong is that physiciansare treating a reading on a blood pressure machine in a cookbookfashion rather than the patient or the cause of the problem.

What Causes Hypertension?

Blood pressure (BP) is essentially determined by cardiac output(CO) or the force with which blood is pumped out of the left ventricleand the degree of systemic vascular resistance (SVR) that is encountered.This is much like Ohm's law governing the strength of an electricalcurrent, so that BP=COxSVR. Hypertension can be caused by increasedcardiac output, increased vascular resistance or both. Althoughthe cause of essential or primary hypertension in a patient maynot be known it is safe to say that it is mediated by one or bothof these two mechanisms.

Prior to these new guidelines, 120/80 was considered to be optimaland 120-129/80-84 was within the normal range. High normal was 130-139/85-89and Stage 1 or mild hypertension was 140-159/90-99. Stage 2 (160-179/100-109),Stage 3 (179-209/100-110) and Stage 4 (>210/>120) reflectedincreasing degrees of severity.

What should you do if one number is highand the other is normal or low? Which is more important, the systolic(upper) or diastolic (lower) measurement? The previousemphasis on diastolic pressure was based on early studies on youngpeople. Diastolic pressure, which is the pressure when your heartrelaxes between beats, rises until around age 55 and then startsto decline. Systolic pressure is the pressure when your heart beatsand it increases steadily with age.

A systolic pressure above 140 with a diastolic pressure below 90is referred to as isolated systolic hypertension. It is common inolder individuals due to hardening of the arteries and slight elevationswere not considered serious. Studies now show that an elevated systolicpressure is an independent risk factor for complications that isfar greater than the risk associated with a high diastolic pressurein older patients with hypertension.

Most patients with hypertension have no symptoms and blood pressureelevations are often discovered during a routine physical examinationor if measurements are obtained in connection with application forlife insurance, employment or blood donation rather than any complaintdue to its presence.

It is important to reemphasize that blood pressures are very variableand that emotional stress and numerous other factors such as smoking,coffee, over the counter drugs containing caffeine or decongestants,a cold room, full bladder, improper cuff size, etc. can all givefalse high readings. Measurements should be taken with the arm supportedat the level of the heart and not until the patient has been sittingfor at least five minutes. If an elevation is found, the blood pressureshould be taken after five minutes in the supine position and thenimmediately on standing and two minutes later to rule out posturaleffects.

At least two readings should be made ateach visit separated by as much time as possible. Three sets ofreadings at least one week apart are advised before prescribingdrugs that may have to be taken perpetually. Measurementsshould be made in both arms and the higher one selected to monitor.Every effort should be made to rule out known causes of hypertension,such as coarctation of the aorta, sleep apnea, obesity, pregnancy,oral contraceptives and other medications.

Narrowing of the renal artery and kidney disease can cause therelease of renin, a powerful hormone that can increase sodium retentionand vascular resistance. Up to 10 percent of hypertension may bedue to endocrine disorders. Primary aldosteronism and Cushing'sdisease can result in an increase of adrenal cortical hormones thatalso cause sodium retention. Pheochromocytoma is a tumor of theadrenal medulla that secretes excess amounts of catecholamines likenoradrenalin and adrenaline that can increase peripheral resistanceas well as cardiac output.

Blood tests can identify these endocrine abnormalities and levelsof chemicals like renin and angiotensin that might determine thecause of hypertension or provide a clue as to the best treatment.High renin hypertension is thought to be associated with higherrates of complications and might respond better to angiotensin convertingenzyme (ACE) inhibitors than diuretics. However, busy doctors don'thave time to go through all the above. It's much easier to prescribea drug and hope it works. If not, there are plenty of others totry.

Read the remainderof this article in the next newsletter issue.