the significance of high blood-pressure


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Page 1: The Significance of High Blood-pressure


The Significance of High Blood-pressure


IN recent years the problem of hypertension hasbeen attacked with increasing vigour from manysides; but despite searching clinical, statistical, andexperimental studies we are still unable to foretellwith any certainty the results of increased blood-

pressure in the individual patient. In the half-centurysince ALLBUTT first showed that hypertension couldoccur in the absence of renal disease the chief advanceshave been the recognition and separation of specificcauses and forms of high blood-pressure. In particular,malignant hypertension has been defined as a fulmina-ting disorder which may complicate any of the hyper-tensive diseases. Endocrine causes, such as Cushing’ssyndrome and phaeochromocytoma of the adrenalmedulla, are now clearly separated, and coarctationof the aorta is readily diagnosed. Chronic pyelo-nephritis and other less obvious forms of renal disease,sometimes affecting only one kidney, are regularlyconsidered and occasionally discovered as the causeof hypertension. Nevertheless, these refinementsof diagnosis are side-issues compared to the main

problem, which concerns the significance of high’blood-pressure in that great majority of patientswho remain in the category of essential hypertension.As ALLBUTT made clear, this disorder is compatiblewith long life and freedom from serious disease ;on the other hand, its complications may cause

sudden death or lifelong invalidism. This dilemma of

prognosis carries unfortunate social implications,for the blood-pressure is becoming an important factorin acceptance for life assurance and superannuationbenefits, and indeed for entry into many occupations.

In our present issue this problem is forcibly statedhy Dr. WILLIAM EvArrs, who has long made a

study of high blood-pressure and its manifestations inpeople of various ages. His thesis is that in both the

young and the old high blood-pressure may follow abenign course for many years without giving rise tocardiovascular complications. This he would term"hypertonia " as distinct from " true arterial hyper-tension," which he associates with cardiovascular

hypertrophy and which carries a grave prognosis,owing particularly to cardiac and cerebral arterialdisease. This thesis is a restatement of the long-recognised fact that the serious manifestations ofhigh blood-pressure are due to arterial degenera-tion, which is accelerated and aggravated by increasedarterial strain. The crucial question is : Why dosome patients with high blood-pressure developarterial degeneration-whether this be the acutearteriolar necrosis of malignant hypertension, or

the slowly evolving atheroma of so-called benignhypertension-whereas others do not ? Clinicalobservation indicates (and Dr. EVANS’s findingssupport this view) that cardiovascular hypertrophyand degeneration develop predominantly in patientswhose blood-pressure, particularly the diastolic com-

ponent, is sustained at a high level, while the morebenign course is associated with a labile and inter-mittent hypertension, which may manifest itselfunder the stress of medical examination. For lifeassurance, only a single estimation of blood-pressureis usually made, and the resulting failure to distinguishbetween sustained hypertension and a labile blood-pressure reacts unfairly on many individuals. Yetit is difficult to see a solution, since the subsequentcourse of a labile blood-pressure is unpredictable.There is considerable evidence that the naturalhistory of


hypertonia " and " true hypertension


are not so clearly distinguishable as Dr. EvArrs

suggests. In his own series, cardiac pain was presentin almost half of the 50 older patients placed in thehypertonia group, and 9 died with cardiac infarction.The younger patients in this category-recruitsfor National Service-showed no evidence of cardio-vascular disease after a ten-year follow-up, but a

further period of observation is necessary before thedevelopment of sustained hypertension and its vascularcomplications can be excluded. An investigation ofthis kind by LEVY et all provided definite supportfor such a sequence of events. From examination ofthe medical records of more than 22,000 U.S. armyofficers over a period of from one to twenty-fiveyears, they obtained evidence that sustained hyper-tension was commoner in those with previous transienthypertension than in those who have shown no previouselevation of blood-pressure. The rates of retirementand death from cardiovascular renal disease were alsoconsistently higher among those with transient

hypertension than in those without. A transitionfrom intermittent to sustained hypertension is oftenseen in chronic renal disease. Recent clinical observa-tions have provided contributory evidence of a

different kind. In many hypertensive disorders ithas been found that the blood-pressure may remainincreased after the original cause has been removed.This may happen in patients with phæochromo-cytoma, Cushing’s syndrome, coarctation of theaorta, or unilateral renal disease. Thus various formsof acute hypertension may give rise to sustained

hypertension, the mechanism of which is differentfrom that of the early phase. It seems justifiableto presume that a similar relationship may holdfor the early and late stages of essential hypertension.The mechanism which sustains chronic hypertensionis obscure. That this mechanism is generalisedorganic narrowing of the arteries is unlikely forseveral reasons, not the least of which is that ifsuch changes are partly attributable to the severityand duration of the hypertension, as there is goodreason to believe, they can hardly be named as thecause of the change from an intermittent to a sustainedlevel.

It is essential, therefore, in assessing prognosis tokeep an open mind about the relation betweendifferent grades of essential hypertension. Whilecardiovascular hypertrophy is directly proportionalto the mechanical stresses produced by increasedarterial pressure, degenerative changes in the heartand blood-vessels depend also on other factors, someof them metabolic, and for this reason atheroma showsan individual variation independent of the blood-

1. Levy, R. L., Hillman, C. C., Stroud, W. D., White, P. D. J. Ass. 1944, 126, 829.

Page 2: The Significance of High Blood-pressure


pressure level. The most striking example of this isthe higher prevalence of vascular degenerative com-plications in men than in women with the same degreeof hypertension. Many workers are investigatingthe aetiological aspects of atheroma, and until theseare more clearly understood we should be in no hurryto accept new concepts or to change the terminology.Meanwhile practice would be improved and muchinjustice avoided if those who use the sphygmo-manometer in routine medical examinations were togive more thought to the significance of a high blood-pressure reading. The distinction should at least bemade between sustained hypertension and a temporaryaberration from the normal. This can be readilydone by repeated estimations, either in the course ofa day or over a longer time, in conditions as free aspossible from physical and emotional disturbance.In addition a search should always be made forthe clinical and cardiographic signs which differen-tiate hypertensive cardiovacular disease from simplehypertension.

1. Oppenheim, H. Mschr. Psychiat. Neurol. 1900, 8, 232.2. Werdnig, G. Arch. Psychiat. 1891, 22, 437.3. Hoffmann, J. Dtsch. Z. Nervenkr. 1893, 10, 292.4. Silvestri, T. Gazz. Osp. Milano, 1909, 30, 577.5. Batten, F. E. Quart. J. Med. 1909, 3, 313.6. Batten, F. E. Proc. R. Soc. Med. (Sect. Neurol.) 1914, 8, 69.7. Spiller, W. G. Brain, 1914, 36, 75.

Amyotonia CongenitaTHE infant with severe hypotonia and impaired

movement of the limbs and often reduction of thetendon reflexes presents a difficult problem in diag-nosis and prognosis. In 1900 OPPENHEIM described

briefly under the name of myatonia congenita infantswho were severely hypotonic with reduced spon-taneous movements but no actual muscle paralysisand with weakened or absent tendon-jerks. He sug-gested that this disorder was due to defective develop-ment of the muscles or of the peripheral motorneurones and that improvement occurred in the courseof time. This condition, which became known asOppenheim’s disease or amyotonia congenita, has beenthe subject of controversy as to whether it is in fact apathological entity. It soon became clear that manyinfants who were severely hypotonic in the first fewweeks or months of life rapidly became worse and died,showing at necropsy degenerative changes in theanterior horn cells similar to those found in theinfantile spinal muscular atrophy which had beendescribed by WERDNIG 2 and by HOFFMANN.3 Inother infants, however, who early in life had shown asimilar clinical picture of gross hypotonia the clinicalcourse and the pathological findings were different.SILVESTRI 4 described 2 children with the clinical

picture of amyotonia congenita in infancy in whomthere was a family history of an aunt with progressivemuscular dystrophy. When the elder of the affectedchildren reached the age of 16 the hypotonia had dis-appeared, but he had the characteristic proximal-muscle wasting and weakness of the Erb type of

progressive muscular dystrophy. BATTEN 5 6 main-tained that the picture of amyotonia congenita couldbe caused by myopathy without involvement of thecentral or peripheral nervous system, and in 1914SPILLER 7 concluded that the clinical picture oj

amyotonia congenita as described by OPPENHEIMcould be caused by several different pathological

processes. SPILLER’S views have been confirmed bysubsequent studies. Although in the majority ofaffected infants who died changes in the anterior-horncells resembled those of the Werdnig-HoHmanndisease,8 several carefully studied cases showed nopathological lesions in the spinal cord.’ 0-13 ALDRENTURNER 14 followed up a family of Batten’s patientsin which 5 members had shown. the typical picture ofamyotonia congenita in infancy, and in adult lifeno hypotonia but localised wasting and weakness ofcertain muscles, especially the sternomastoids andshoulder-girdle muscles. The disorder appeared to benon-progressive, and on clinical grounds ALDRENTURNER suggested that it was a congenital myopathy.This was subsequently con.firmed 15 when 1 of the

patients died of bacterial endocarditis and no abnor-mality was found in the central nervous system onthorough examination, while sections of affectedmuscles showed changes resembling those in myopathicmuscles.

In the past few years follow-up studies of childrenwho showed the clinical syndrome of amyotoniacongenita in infancy have been carried out in Denmarkby BRANDT 16 17 and in England by WALTON.18-20BRANDT studied 131 children who had muscular

hypotonia and weakness beginning at birth or in thefirst year of life. He found that 87 probably hadprogressive spinal muscular atrophy (Werdnig-Hoffmann), and in 28 the hypotonia was symptomaticof various conditions such as mental deficiency,cerebral diplegia, or nutritional or metabolic disorderssuch as rickets. There were 13 other patients, ofwhom 6 recovered apparently completely, 3 improvedstrikingly, 3 improved but remained disabled, and 1died of pneumonia after improving somewhat. BRANDTthought that these cases were a heterogeneous group,but that at least 3 resembled the congenital non-progressive myopathy originally described by BATTEN.WALTON’s series was of 109 patients in whom amyo-tonia congenita had been diagnosed in early childhood.The follow-up showed that 67 had infantile spinalmuscular atrophy of which the prognosis was bad;55 died between the ages of 5 weeks and 12 years, whilethe 12 survivors were all severely disabled, the eldestbeing aged 20. There were 3 cases of progressivemuscular dystrophy and 1 of polymyositis, and in 20cases the hypotonia was symptomatic of variousconditions such as mental deficiency and cerebraldiplegia. (Infantile polyneuritis as a cause of the

syndrome, although not encountered by WALTON, hasbeen recorded.21) The remaining 17 patients inWALTON’S series were of particular importance. Theywere all limp, floppy children who showed considerabledelay in reaching the milestones indicating increasingmuscular activity ; but as they got older they all

improved, 8 recovering completely between the ages of5 and 15 years. In the other 9 the hypotonia gradually8. Greenfield, J. G., Stern, R. O. Ibid, 1927, 50, 652.9. De Lange, C. Acta pœdiat., Stockh. 1937, 20, suppl. 3.

10. Councilman, T., Dunn, C. H. Amer. J. Dis. Child. 1911, 2, 340.11. Haushalter, P. Arch. Méd. Enf. 1920, 23, 133.12. Silberberg, M. Virchows Arch. 1923, 242, 42.13. Menges, O. Dtsch. Z. Nervenheilk. 1931, 121, 240.14. Aldren Turner, J. W. Brain, 1940, 63, 163.15. Aldren Turner, J. W. Ibid, 1949, 72, 25.16. Brandt, S. J. Child Psychiat. 1948, 1, 266.17. Brandt, S. Werdnig-Hoffmann’s Infantile Progressive Muscular

Atrophy. Copenhagen, 1950.18. Walton, J. N. Lancet, 1956, i, 1023.19. Walton, J. N. Proc. R. Soc. Med. 1957, 50, 301.20. Walton, J. N. J. Neurol. Neurosurg. Psychiat. 1957, 20, 144.21. Chambers, R., MacDermot, V. Lancet, 1957, i, 397.