Discussion DISCUSSION The present study was conducted to assess the sympathetic reactivity by bloodpressure response to static exercise among the medical students with parental history ofhypertension. Audiovisual reaction time & anxiety levels were also studied in these children. In the present study it was observed that 81.67% students had a history ofhypertension in either parent, out of whom 58.4% students had a history of hypertension infather & 23.3% students had a history of hypertension in mother & 18.33% students hadhistory of hypertension in both the parents. The strength of hereditary risk in causation ofdiseases doubles with single first degree hypertensive relative & quadruples with two suchrelatives.73Some studies in the past have reported the probability of developing hypertension in theoffspring’s of hypertensive parents in future to be 25%, if the children had history ofhypertension in either of the parent ; 50%, if children had history of hypertension in both theparents. 15 This indicates major role of genetics in acquiring the disease even though manyconfounding factors such as age, gender, lifestyle, stress ; environmental factors also play animportant role in causation of disease. 74 Johns Hopkins Precursors Study also reported astrong incidence of acquiring hypertension in adult life with history of hypertension in bothparents. 75 In the present study BMI score, resting PR ; BP was slightly higher amongchildren of hypertensive parents. Many studies have found significant rise in BMI ; SBP inthe genetically susceptible individuals who inherit these traits as recessive inheritance fromeither or both parents suffering from hypertension. 14,76
Discussion Many other studies observed that the offspring’s of hypertensive parents showed alteredlipid profile along with elevated PR, DBP & mean arterial blood pressure (MABP) levelswhich was found to be more pronounced in consanguineous population. The underlyingmechanism was explained on the basis of increased sympathetic activity in these childrenwith high plasma catecholamine levels before exercise. 77, 78, 79 Sympathetic overactivity & high BMI mutually influence the ongoingpathophysiological processes & act as an additional triggering factor to already existingvasoconstriction & retention of sodium due to increased renal sympathetic activity. Highlevel of insulin with increased resistance, raised level of leptin along with free fatty acids &endothelial dysfunction further accelerate the damage associated with sympatheticoveractivity. 14, 80 The elevated BP & BMI was also attributed to multiple gene variation &their interactions that regulate BP in response to mental and physical stress. Earlier studyreported no change in resting DBP in offspring’s of hypertensive parents in contrast to otherstudy which observed high resting DBP in these children. 81 In the present study there was statistically significant increase in DBP ; SBPduring isometric handgrip-test. Rise in systolic ; diastolic blood pressure with hand gripdynamometer is an indicator of increased sympathetic activity. 82 The increased afterload tothe heart due to constriction of blood vessels in exercising muscles and increased peripheralvasoconstriction mediated through adrenergic receptors of sympathetic nervous system isresponsible for rise in DBP during IHG exercise. Further the metabolites that accumulate inthe exercising muscle like lactic acid and adenosine are sensed by metabosensitive nerveendings in the interstitium of skeletal muscle cause release of afferent discharge of group IVnerves, thus increase the sympathetic reflex activity. Similar observation was reported in fewstudies earlier, along with high resting PR and BP in children of hypertensive parents. 18, 24
Discussion The muscle sympathetic nerve activity, which is under the control of baroreflexshows reduced sensitivity among the children of hypertensive parents. Due to which thesympathetic vasomotor tone is high in them, thus increases the chances of developinghypertension in future. Further explanation for increased peripheral resistance and in turnDBP during IHG exercise is due to sustained muscle contraction that decreases blood flow tothe exercising muscle, thus increasing pressure response and perfusion pressure to activemuscles. It is also seen that static isometric exercise increases endothelin-1 secretion alongwith reflex release of nor-epinephrine that is mediated by hypothalamus. This findingsupports the concept of inherited vascular reactivity in the genetically susceptible individuals; taken as early predictor of development of neurogenic hypertension. 6, 24The high bloodpressure reactivity is labeled as biobehavioural risk factor that has harmful effect on cognitivefunctions like attention, verbal memory ; confrontation naming. 83 Some studies have also reported of high sympathetic activity is associated withreduced cognitive performance. 84 In the present study AVRT was performed to assesscognition ; sensory motor coordination. It was found that students of hypertensive parentsshowed delayed response to both ART ; VRT of which delayed ART was statisticallysignificant. Many studies have used audiovisual reaction time as a tool to measure sensorymotor intactness, coordination ; information processing speed in middle aged hypertensivecases. The previous study observed longer VRT and impaired cognition in known cases ofhypertension. They also found positive correlation between RT ; duration of hypertension,reflecting the harmful effect of elevated BP on nerve conduction velocity in long run. 26 The underlying pathology explained was inflammatory nerve cell injury tobasement membrane, axonal degeneration-atrophy ; micro thrombi causing endoneuralhypoxia in both slow ; fast conducting fibers. The peripheral nerves were more vulnerable to
Discussionearly hypertensive changes causing hypertensive neuropathy. The reduced blood supply ;metabolism to the brain tissue was mainly found in the fronto-temporal ; subcortical areasthus affecting cognitive functions in hypertensive patients. The high BP is also damages theblood brain barrier ; hastens the easy accessibility of toxins into the brain tissue. Theduration of hypertension is found to be associated with atherosclerotic changes in bloodvessels causing hypoxic-ischemia related complications. Many studies on clinical trial haveshown improvement in neuropathy ; cognitive functions on proper antihypertensivesmedication in hypertensive patients. 26 Many studies support the finding of ART to be faster than VRT, as auditorystimuli reaches motor cortex within 8-10 ms ; visual stimuli takes longer time, around 20-40ms for the same. In present study AVRT response was found to be longer for visual redcolor stimuli ; auditory click stimuli in children of hypertensive. Many studies on VRTconducted in normotensive individuals in the past have observed contrasting finding forvisual red/green color and concluded that reaction time ; chromaticity does not show anycorrelation. This needs to be further evaluated to study the harmful effect of high bloodpressure on chromaticity ; color perception. Though studies on microvascular changes inpopulation aging ; 6years with parental history of hypertension have reported narrowing ofretinal arterioles, mainly in female child with associated high prevalence of myopia in them.Though the cause for gender difference is unclear but the vascular changes were attributed top-selectin mediated activation of C-reactive protein causing platelet adhesion ; endothelialdysfunction. 84, 85, 86 The association between anxiety ; hypertension is investigated in many crosssectional ; prospective studies have given inconsistent results. Some studies reportinganxiety as high risk factor in causation of the disease and some reported even decreased BP in
Discussionhypertensive patients. 89The present study observed slightly higher levels of anxiety amongchildren of hypertensive parents. To the best of our knowledge/finding/search there is meagerliterature available that confirms offspring’s of hypertensive parents inherit & exhibit highlevels of anxiety. As sympathetic overactivity is associated with high arousal levels, we cansay that some amount of anxiety is present in the children of hypertensive parents. Thecommon emotional relationship & family environment they share also play a role incausation of the disease. Studies in past on assessment of anxiety levels in diagnosed casesof hypertension between 40-60 years age group have found strong association of anxiety andhypertension. Anxiety causes short term increases BP through renin angiotensin system,hypothalamo-pitutary-adernal axis dysfunction with sympathetic over activation causingincreased renal water-sodium retention increasing the blood pressure .Also sympatheticoveractivity causes abnormal haemodynamic changes and lipid metabolism & endothelialcell damage to increase the blood pressure. 90, 91

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