Genetics, Lifestyle Factors Effects On Hypertension And Non-pharmacologic Management Flashcards
What is the mosaic of BP
BP can be affected by:
Haemodynamics
Humoral
Intrauterine programming
Endocrine system
Neural system
Adaptive
Anatomical
Renal system
Environment
Genetics
Genetic determinants of hypertension
Twin studies show 30-50% of variation of blood pressure is due to genetics
New studies suggest hypertension is polygenic
There are a few rare Mendelian forms of hypertension
GWAS showed >901 loci affecting BP associated with a combine 10.4 mmHg higher SBP
- individual variants identified only explain 1mmHg/allele for SBP and 0.5mmHg/allele for DBP
Lifestyle Factors for Uncomplicated Hypertension
Aging
Obesity and insulin resistance
High salt diet
Low potassium diet
Sedentariness
Stress
How does Aging affect risk of Hypertension
Normally aorta cushions pulsatile SBP due to elastin in intima-medial wall
- as you age, elastin is replaced by collagen causing arterial stiffness and widening of pulse pressure (diff b/w SBP and DBP increases)
- after mid 50s, SBP increases and DBP plateaus or decreases —> more at risk for isolated systolic hypertension
How does Obesity and insulin resistance increase risk of Hypertension
- MOA
-Every 10% increase in weight is associated with an increase of 6.5mmHg SBP
- obesity and weight gain account for 25% of all hypertension
- is the most common cause of adolescent HT
MOA:
1) Increased plasma volume and CO
2) RAAS activation including activation of mineralcorticoid receptors
3) shifting of pressure natriuresis to a higher BP threshold in obesity
4) sympathetic nervous system activation
Sedentariness and Exercise and relation to hypertension risk
Associated with increased incident hypertension and mortality
>4 hours a day of screen time with hyperinsulinemia even among those physically active
- chronic, unbroken periods of muscular unloading causes suppression of SK. Muscle lipoprotein lipase activity (necessary for HDL production) and reduced glucose uptake
- taking breaks was beneficially associated with decreased waist circumference, body mass index, and 2-h plasma glucose
Dietary Sodium intake and relation to Hypertension
HT doesn’t usually occur in societies with very low Na consumption
- global mean Na intake was 3.95g/day (10g/day salt)
- Canada’s guideline is 2g/day and 1tsp salt = 5mg
75% of daily Na intake comes from processed foods and restaurants
Sodium Sensitivity
Extend of BP change after abrupt changes in salt intake vary considerably from one individual to another (as well as in the same individual if tested at different times)
Salt sensitivity increases with age and is more prominent in African Americans, obese people and patients with metabolic syndrome or chronic kidney disease
Impaired renal sodium excretion can lead to initial volume expansion and then hypertension
Dietary Potassium Intake and Relation to HT
MOA
BP is inversely related to Potassium intake
Low intake (<40 med/day (or 1.5g/day or 120mmol/day))
- average consumption is <70-80 molecules/day in most countries due to food processing and lack of fruits and veggies
Increased potassium decreased SBP by 3.5mmHg and DBP by 1.95mmHg and there is a protective effect against stroke
MOA:
- sodium excretion is diminished by hypokalemia via increases of sodium reabsorption —> low potassium increases NCC expression and causes increased reabsorption of Na
Stress and its effects of HT
- significantly related to hypertension
- Siegrist’s model as (1) high imbalance, a combination of high effort and low reward at work or (2) high over-commitment, and exhaustive work-related coping style indexing the inability to unwind showed high imbalance but not over-commitment was associated with increased SBP
Work hypertension is called MASKED Hypertension
Masked Hypertension
Work hypertension caused by high imbalance causing increased SBP
Alcohol relation to HT
MOA
Excessive intake is related to development of HT
> 2 drinks/day have a 1.5-2fold increase in HT
Dose-related and especially when intake is >5 drinks/day
MOA:
- stimulation of SNS, RAAS, raised cortisol levels, inhibition of nitric oxide
Other causes of Hypertension
Stimulants - cocaine and amphetamines
Decongestants - pseudophedrine
Prednisone
Oral contraceptive pills
Some anti-depressants - TCA’s and SSRIs
NSAIDs
Supplements - St. John’s Wort, Ephedra, Ginko, Ginseng
Health Behaviour change to treat Hypertension
Physical exercise - 30-60 moderate intensity dynamic exercise 4-7 days per week
Weight reduction - BMI between 18.5-24.9 and waist circumference <102cm men and <88cm women
Alcohol consumption (two or less per day; Men <14/week; Women <9/week
Diet (DASH diet - emphasis on fruits, veggies, low fat dairy, fibre, whole grains, protein from plant sources low in saturated fat, high calcium, magnesium and potassium)
Sodium reduction towards 2000mg/day (5g salt)
Stress management via CBT and relaxation techniques
Smoking cessation and smoke-free environment
Potassium Supplementation
How does exercise reduce risk of developing HT?
Exercise training increases endothelial production of NO synthase, decreases aortic stiffness and increases whole-body insulin sensitivity
Also reduces circulating NE and vascular resistance and hyperinsulinemia
OSA-CPAP relation to cardiovascular disease and BP
Showed now difference in cardiovascular outcome but improved daytime sleepiness and QoL
Showed improvements in BP lowering diastolic BP by 5mmHg