Review of literature 3

Review of literature 3. REVIEW OF LITERATURE Hypertension is a chronic, non- communicable, life threatening medical condition. Itis preventable & modifiable disease, if not addressed at the earliest it can progress over thelife span and cause complications like myocardial infarction, stroke and renal failure andother end organ damage. 2,6,18 Due to the rising prevalence & interplay of genetics andmodifiable lifestyle risk factors in its causation, the disease has grabbed the attention ofresearchers and health care providers. Studies in the past on hypertension stressed upon assessment of knowledge & itsprevalence in general population all over the globe. In recent times, literature on hypertensionhave elaborated upon the role of genetics in acquiring essential hypertension & its long termcomplications like impairment of neuro-cognitive functions in children with parental historyof hypertension. It is well documented fact in many studies that offspring’s of hypertensiveparents exhibit autonomic dysfunction in the form of sympathetic hyperactivity ; slowingdown of parasympathetic activity. 3, 4, 23, 24 Autonomic nervous system via sympathetic branch, that helps an individual intackling stressful situation, mainly regulates BP ; is excitatory to heart and blood vesselcausing rise in HR, cardiac contractility ; vasoconstriction. Parasympathetic branch i.e.,inhibitory innervations via vagus nerve, regulates cardiac function which decreases HR ;cardiac contractility mainly during emotional state. Cardiovascular system fails to controlcardiac and vasomotor sympathetic drive associated with many cardiovascular diseases likehypertension and leads to worsening of the condition if autonomic imbalance occurs in theform of excessive sympathetic excitation and slowing down of parasympathetic activity.25 This sympathetic reactivity in the form of high blood pressure has a negative impacton neuro-cognitive functions in long run.17 The impact of hypertension on cognition has
Review of literaturebeen studied by many researchers using audiovisual reaction time and its validity as one ofthe reliable ; age old standard test to assess cognition (like alertness, quickness, decisionmaking) and sensory motor function has been documented. 26, 27 Stress and anxiety act as important risk factors in pathogenesis and progressionof the disease outcome ; the same is confirmed by many studies.20,28 Hamilton AnxietyRating Scale is a subjective assessment scale (HAM-A) that is validated as a reliableQuestionnaire to assess anxiety levels in many studies.29 The studies on children with familyhistory of hypertension also highlighted upon the importance of periodic evaluation of highrisk groups, early diagnosis and lifestyle modification in them, so as to halt the progress ofthe disease and reduce the disability adjusted life years associated with high blood pressure.30 Landmarks in the history of hypertension: Blood pressure “is defined as the lateral pressure exerted by column offlowing blood on the walls of arteries”. Blood pressure usually measures mean arterialpressure. The blood pressure measured at anytime of the day is defined as casual bloodpressure ; if recorded in the basal state (complete physical ; mental rest ; after 12 hrs offasting) is called basal blood pressure. 31 The understanding of present modern terminology “Hypertension” for an ancientterm “hard pulse” can be traced back to Indian ayurvedic and Chines ancient medicine,wherein a trained physician was able to assess working of cardiovascular system by gentlypalpating the radial pulse. The credit for modern concept of hypertension ; description ofthe term essential hypertension goes to Frederick Akbar Mahomed (1849–1884).He was anIrish-Indian physician working at Guy’s Hospital, London. He also demonstrated that highBP was more commonly recorded in older population. He also found that younger individuals
Review of literatureexhibited high BP that affected heart, kidney and brain in long run. The modern quantitativeconcept of hypertension came into existence in early 20th century, following invention ofmercury sphygmomanometer and definition of korotkoff sound in which appearance anddisappearance of sounds were SBP/DBP respectively. ‘Hypertension’ as a disease, was recognized following the death of USPresident F.D. Roosevelt. The cause of death was later diagnosed to be raised BP, that wasrecorded in him 2 months prior of him suffering from fatal hemorrhagic stroke. Followingthis incidence many insurance companies in USA made measurement of BP mandatory ingeneral physical examination. After 3 years following the death of F.D. Roosevelt, NationalHeart Act was signed by the then US president Truman, which paved way for manyresearches in cardiovascular studies like Framingham Heart Study. Actuarial Society ofAmerica, on the basis of their large scale researches pointed out that high BP is associatedwith high morbidity and mortality. 32Definition of hypertension by JNC VII: Hypertension is defined as sustained blood pressure ?140 mmHg of SBP & ?90mmHg of DBP (JNC VII, 2003). Further JNC VII categorized hypertension as Stage I-SBP/DBP is 140-159mmHg/ 90-99 mmHg and Stage II – SBP is ?160 mmHg & DBP is?100 mmHg. The report also observed that when the SBP ranged between 115 mmHg &DBP range of 75 mmHg, with every increase of 20/10 mmHg recording, the cardiovascularrisk doubles. Pre hypertension state is defined as SBP/DBP between 120 – 139/80 – 90mmHg. 33Prevalence of hypertension with respect to world and India: The data on