Hypertension - definitions, etiology and mechanisms

hypertension, prehypertension, refractory hypertension, hypertensive urgencies and emergencies, hypertensive crisis, essential hypertension, secondary hypertension, etiology, mechanisms

1. Hypertension –Definitions and
Mechanisms
Dr. Md.ToufiqurRahman
MBBS, FCPS, MD, FACC, FESC, FRCPE, FSCAI,
FAPSC, FAPSIC, FAHA, FCCP,FRCPG
Associate Professor of Cardiology
National Institute of Cardiovascular Diseases,
Sher-e-BanglaNagar, Dhaka-1207
Consultant, Medinova, Malibaghbranch
Honorary Consultant, Apollo Hospitals, Dhaka and
STS Life Care Centre, Dhanmondi
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2. Definition
Bloodpressure(BP)inhumanpopulationshasanor
maldistribution.
Accordingly,thedefinitionsof"normal"BPandofva
riousformsof hypertensionarearbitrary,but
areneededforpracticalreasonsintheassessment
andtreatmentofpatients.
Hypertensionisdefinedasasystolicbloodpressure
(SBP)of140mmHgorgreater
and/oradiastolicbloodpressure(DBP)of90mm
Hgorgreaterinpersonsnot
takingantihypertensivemedication
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3. Pre Hypertension
ThosewithaBPof120-
139mmHgsystolicand/or80-
89mmHgdiastolicareclassifiedas"prehypert
ensive,"nowknowntoincreasetheriskofany
CVeventbytwo-
tofourfoldcomparedwithanormalBP(<120
/80mmHg).
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4. Isolated systolic hypertension
Ageingisassociatedwithaprogressiveincreasein
systolicBP,areductionindiastolicBP,andwideningo
fthepulsepressure.Thisisareflectionofa
progressivereductioninthecompliance,orstiffening,
oflargeconduitarteries.
"Isolatedsystolichypertension"(ISH),thepredominant
formofhypertensionintheelderly,isdefinedasa
SBPof140mmHgorgreaterinthepresenceofa
DBPof90mmHgorlower.
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5. Essential,primary,oridiopathichypertension
"Essential,primary,oridiopathichypertension,"define
dashighBPdueneithertosecondarycausesnor
toaMendelian(monogenetic)disorder,accountsfor
90%of allcases.
Theterm"primaryhypertension"ispreferred,since“
essentialhypertension"representsanarchaic
misunderstandingofpathophysiology,namely
thathypertensionis"essential"tomaintainbloodflow
throughseverelynarrowed resistancevessels.
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6. Secondaryhypertension
"Secondaryhypertension"ishighBPcausedbyaniden
tifiableandpotentiallycurabledisorder.
"Refractoryorresistanthypertension"isdefinedasa
BPof≥140/90mmHgdespitethreedrugsofdifferent
classesat maximumapproved
doses,givenforatleast1month.
"Spurioushypertension(pseudohypertension)"is
artefactuallyelevatedBPobtainedbyindirectcuff
measurementoverarigid,oftencalcified,brachial
artery.
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7. Whitecoathypertension
"White-
coathypertension"describespatientswhoseBPishigh(
>140/90mmHg)inanofficeorclinicsetting,witha
normaldaytimeambulatorypressure(<135/85mmHg).
Thisisarelativelybenignconditionwithlowriskofmorbid
events;however,the risk mayincreasewithlong-
termfollowup(6yearsormore).
Antihypertensivemedicationinwhite-
coathypertensionpatientsmaydecreaseclinicBP,but
produceslittleornochangeinambulatoryBP;thus,drug
treatmentmaynotconfer substantialbenefit.

8. Maskedhypertension
"Maskedhypertension"isthemirrorimageof
whitecoathypertension.
Here,theclinicBPisnormal,butambulatoryorho
memeasurementsarehigh,andassociatedwith
highrisk.Althoughtheprevalenceofmasked
hypertensionislow,
perhapsonly6%ofthenormotensivepopulation,
theabsolutenumberintheUnited
Statesmayapproach1518million.

9. Hypertensivecrisis
"hypertensivecrisis"encompassesbothhyperte
nsiveurgencyandhypertensiveemergency.
"Hypertensiveurgency"isdefinedasDBP>120
mmHgintheabsenceofacuteorrapidlywors
eningtargetorgandamage.

10. Hypertensiveemergency
"Hypertensiveemergency"isdefinedasacuteorrapidly
worseningtarget-
organdamageoccurringina hypertensivepatie
ntinassociationwithelevatedBP, but
irrespectiveofthespecificBPlevelattained.
"Malignanthypertension"isahypertensiveemergency
associatedwithpapilledema,whereas "
acceleratedhypertension"isahypertensiveemergency
associatedwithretinalhemorrhages andexudates.

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30. Summary
Hypertensionisverycommoninnearlyallpopulations
,andisamajorindependentriskfactorforCVD.
ThereisagradedrelationshipbetweenBPandCVrisk,
withnoapparentlowerlimit.
BPtargetsare<130/80mmHgforthosewithdiabetes
,kidneydisease,andcoronaryarterydisease.
Theetiologyofhypertensionismultifactorial;
monogeneticformsarerare.
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31. Summary
Keyelementsintheetiologyareactivationofneurohormonal
systems(sympatheticnervoussystem,RAAS,ET);
increasedoxidativestress;altered
cellulariontransportofsodium,potassium,andcalcium;and
abnormalitiesofendothelialfunctionandvascular
reactivity,largearterycompliance,andsmallartery/
arteriolarresistance.
Themaintarget-
organeffectsandresultantCVDeventsareatherosclerotic
vasculardisease;MI,LVhypertrophy,
atrialfibrillation,heartfailure;stroke,encephalopathy,
dementia,andrenalfailure.
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32. Thank you !
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