Hypertension Flashcards
HTN is the major risk factor for __
HTN is the major risk factor for cardiovascular disease
What is the effect of low potassium intake on sodium levels
low potassium intake results in sodium retention
What is sodium sensitivity?
an increase in blood pressure in response to a higher sodium chloride intake than that in the baseline diet
Human kidneys are poised to __ sodium and __ potassium.
Human kidneys are poised to conserve sodium and excrete potassium.
aldosterone and sodium levels
aldosterone results in sodium retention
how does excess of sodium and deficit of potassium lead to an increase in arterial and arteriolar smooth-muscle tone
Deficit K leads to an inhibition of Na+/K+ ATPase (sodium pump) and the potassium channel in the smooth muscle cell
The inhibition of the sodium pump and the resulting stimulation of the sodium–calcium exchanger type 1 (NCX1) increase the intracellular concentration of calcium that in turn triggers actin–myosin interaction and stimulation of vascular contraction.
What are the major forms of cardiovascualr disease
§ Hypertension
§ Atherosclerosis
§ Ischemic heart disease
§ Peripheral vascular disease
§ Heart failure
§ Cerebrovascular disease
what is a CDV
it’s an umbrella term- a disease of heart and blood vessels
What are the leadign causes of death in canada?
Cancer
Diseases of the heart
Cerebrovascular diseases
Other
What are the cnages in the trends in prevalence of reported hypertension
In recent years high blood pressure became mor eprevalent in males than females, eventhough it used to be vise-versa before
- might be due to higher obesity and overweight rate in males who are now became more susceptible to hypertension
How is age and sex related to the risk of HTN?
age is a risk factor
before the age of menopause, prevalence is lower in females
after the menopause, the risk in females becomes somewhat same as in males
then in 75+ males are lower at risk
this might be sue to the fact that there are more females who are older
Awareness and treament of HTN stats
65%- treated by hypertension and controlles
18%- unaware
14%- treated, not controlles
4%- aware, not treated
- Hypertension is __ and __- Antihypertensives are one of the most __ drug categories
Hypertension is prevalent and costly- Antihypertensives are one of the most expensive drug categories
How many cnadians are affected by HTN
Affects >1 in 5 (≅22% of Canadian adults aged >20 y). Since 18% of individuals with hypertension are not aware of their condition, the true prevalence of hypertension is likely higher.
The lifetime risk for developing hypertension among adults aged 55 to 65 years with normal blood pressure is _%.
The lifetime risk for developing hypertension among adults aged 55 to 65 years with normal blood pressure is 90%.
What is the most common reason to visit a doctor?
HTN
What is the number one reason for taking meds?
HTN
Which rases are more/less susceptible to HTN?
- African-americans ≅ 44%
- Whites ≅ 33%
- Hispanic ≅ 28%
- Filipinos, Japanese ≅ 26%
- Chinese, Korean ≅17%
Is there a genetic component to HTN
yes
Is HTN more prevalent in canada or US
US
How to calculate MAP?
mean arterial pressure = cardiac output X peripheral resistance
how to calculate cardiac output and what are the untis? what does it measure
CO (L/min) = stroke volume (L/beat) x heart rate (beats/min)
the volume of blood that the herat is pumphing per minute
unit: l/minute
How to calculate resistance? What are the units? How does vasoconstriciton adn vasolidation affect it?
- resistance against which your heart is pumping the blood
- radius has a bigger impact on the resistance over length or viscosity
- (length of vessel x viscosity of the blood)/ (radius^4)
- in vasoconstriction: resistance ↑
- in vasodilation: resistance ↓
Wghat is Mean arterial pressure (MAP) is regulated by?
Sympathetic nervous system
Renin-angiotensin-aldosterone system
Renal function- fluid and electrolyte control
Hormones involved: epinephrine, vasopressin, angiotensin II
Factors Influencing Arterial BP
Cardiac output - heart rate x stroke volume
heart rate is regulated by ANS
Para and sympa
sympa actvity decreases HR
parasympathetic decreases HR
Sympathetic NS increases stroke volume by causing blood vessels to contract more
Stroke volume- amount of blood pumped by the heart
increases with sympathetic NS and epinephrin
Sympathetic NS increases stroke volume by causing blood vessels to contract more
venous blood- return of blood from periphery
the more blood returned- the higher the stroke volume
venous return increases with the activity of respiratory pump- helps blood to go from area of higher to lower pressure-> go back towards the heart
skeletal activity- contraction of the muscles against the veins which will help to bring the blood back up
cardiac suction effect
heart acts as a pump- contract and changes the pressure at the levels of the heart which pushes blood through the heart
venous volume is dependent on the effective blood volume
blood volume is controlled in short term by fluid shift in the compartments of the body;
in longe term -RAAS, kidneys, vasopressin and salt and fluid levels
Total peripheral resistance
resistance depends on the radius and viscosity; directly proportional to viscosity and inversely proportional to the radius
blood viscosity increases with the amount of RBC (higher Htc-> higher viscosity) .hematocrit is regulated within certain limit
muscles need more nutrients during the exercise- will make vessels expand- local regulatory control in the muscles
extrinsic vasoconstrictive control- sympathetic activity and epinephrin-> constriction of blood vessels
angiotensin and vasopressin result in the constriciton of blood vessels
Renin-Angiotensin-Aldosterone System (RAAS)
change in osmolarity of blood volume will tigger negative feedback
kidneys detect changes in the blood pressure- changes in electrolytes, fluid levels
they will release renin
renin will act upon angiotensiongen (inactive, released by the liver) and will convert it into angiotensin I
angiotensin I will reach the lungs where it will be converted into angiotensin II by angiotensin-converting enzyme (ACE)
angiotensin II will act on adrenal cortex and result in the release of aldosterone
aldosterone will act on kidneys to make more Na reabsorption by the kidney tubules; chloride will follow-> Na and Cl are conserved
osmosis will follow resulting in water reabsorption
angiotensin II acts on artery radius-> vasoconstriction-> increased blood pressure
also stimulates the thirst signal from hypothalamus-> increased fluid intake
stimulates vasopressin release from pituitary gland-> vasopressin acts on kidney tubules will increase water reabsorption
aldosterone acts both on water and electrolytes
vasopressin acts upon fluid mainly-> reabsorption
Target organ damage related to hypertension
heart: LVH (eft ventricular hypertrophy), CHD, CHF (congestive heart failure)
Brain: Hemorrhage, Stroke, dementia
Eyes: Retinopathy
Blood vessels: Peripheral Vascular Disease
Kidneys: Renal Failure, Proteinuria
How is the Measurement of BP done?
sphygmomanometer, in mmHg
What are the 2 types of causes of HTN?
§ primary/essential
§ secondary
Describe primary causes of HTN?
Primary/essential/ idiopathic (95% of cases)
- Unknown etiology
- Interaction from environmental and genetics factors
- Influenced by dietary and behavioral factors
Describe secondary causes of HTN?
(5% of cases)
Occurs secondary to another condition such as renal, endocrine, or neurological disorders
What are the symptoms of HTN?
§Hypertension is typically asymptomatic (« silent killer »)- can go on untoticed for a long period of time
Major risk factors of HTN
Non-modifiable
- Age >60 y
- Men, postmenopausal women (due to lower levels of estrogen), ethnicity (African-American, Russians, Finns)
- Family history of CVD : women <65 y or men <55 y- premature CVD
Modifiable
- Smoking
- Sedentary lifestyle
- Abdominal obesity, insulin resistance
- Excess sodium intake
- Poor diet quality
- Stress
Hypertension – Contributing Factors and Mechanisms
- Excessive secretion of vasopressin and angiotensin II: ↑ vasoconstriction and fluid retention
- Smoking: interferes with NO-> impairs endothelial vasodilation as NO usually helps vasodilation
- Renal disease: reduced blood flow-> ↑ angiotensin IIàvasoconstriction + Na+, Cl-, water retention-> blood volume
- Adrenal disorders: Adrenal disorders that ↑ secretion of epinephrine and norepinephrine -> vasoconstriction, ↑ cardiac output
- Hyperinsulinemia is associated: mechanisms unclear
- Neurological diseases
WHO Classification of HTN
* measured on 2 or more ocassions
Target organ damage and associated clinical conditions (ACC)- heart
Cardiovascular disease :
- Coronary artery disease : angina or prior MI
- Left ventricular hypertrophy or dysfunction
- Heart failure
Target organ damage and associated clinical conditions (ACC)- brain
Cerebrovascular disease
- Stroke or TIA (transcient ischemic attack)
- Hemorrhage
- Dementia
Target organ damage and associated clinical conditions (ACC)- eyes
retiopathy
Target organ damage and associated clinical conditions (ACC)- blood vessels
Peripheral artery disease
Target organ damage and associated clinical conditions (ACC)- nephrones
§ Albuminuria
§ Chronic kidney disease
What are the characteristics of a low risk-patient?
No target organ damage ot cardiovascular risk factros
What are the characteristics of a moderate-to-high risk factor patient?
multiple cardiovascular risk factros & 10-year global risk < 15%
What are the characteristics of a high risk factor patient?
Individuals with one or more of the following clinical indications should consent to intensive management:
- Clinical or sub-clinical cardiovascular disease
OR
- Chronic kidney disease
OR
- Estimated 10-year global cardiovascular risk ≥15%
OR
- Age ≥75 years
Hypertension Canada High-Risk Patient BP cutoffs for initiaiton of antihypertensive therapy and BP treatment target
BP measurement methods
Office:
- Preferred: Automated office blood pressure (AOBP)- Oscillometric (electronic)
- Non-automated (manual) office BP” Non-AOBP Auscultatory (mercury)
Office Automated (unattended, AOBP)
- Oscillometric (electronic)
Out of office BP measurement methods:
Ambulatory (ABPM)
Hypertension Diagnostic Algorithm
1) If AOBP is used, use the mean calculated and displayed by the device. If non-AOBP (see note 2) is used, take at least three readings, discard the first and calculate the mean of the remaining measurements.
4) Serial office measurements over 3-5 visits can be used if ABPM or home measurement not available.
5) Home BP Series: Two readings taken each morning and evening for 7 days (28 total). Discard first day readings and average the last 6 days.
6) Annual BP measurement is recommended to detect progression to hypertension.
Hypertension treatment goals
Reduce risk of CD and renal disease; and target organ damage
Lower BP to clinically appropriate level
Hypertension – Comprehensive Treatment plan includes:
- Physical activity
- Weight reduction
- Nutrition therapy
- Moderation in alcohol, relaxation therapy, smoking cessation
- Pharmacological interventions: loop diuretics; thiazides; carbonic anhydrase inhibitors; potassium sparing diuretics
!!!pills are never used on their own!!!
Dietary factors involved in hypertension
- High calories, excess weight, obesity
- Sodium- big infuence
- Potassium- big influence
- Calcium
- Magnesium
- Alcohol
Obesity and hypertension in adults <55 y.o
§ Direct link between excess weight and HTN
§ 60% of those with excess weight and normal BP will develop HTN in the next 4 years
§ Abdominal obesity is more associated (than just obesity/ subcutaneous fat)
causes of HTN associated with obesity
§ Insulin resistance/hyperinsulinemia
§ Overactivity of the sympathetic nervous system
§ Alterations in the RAAS
§ Leptin increases sympathetic activity; this function is preserved with leptin resistance- the effect leptin has on HTN is still the same even if leptin resistance has been developed
What is the most potent non-pharmacological approach for HTN treatment?
weight loss
How does weigth loss affect HTN?
- Reduced BP is measured even before healthy weight is reached: 5-20 mmHg per 10 kg loss
- Weight loss is indicated both in treatment and prevention of HTN
Recommendations for weight loss for HTN
- Aim for BMI ≤ 25 kg/m2 + waist circumference <102 cm men, <88 cm in
women
- All overweight patients should achieve a weight loss of 5 kg (↓ SPB by 4.4 and DPB by 3.6 mmHg) to reduce BP and risks for organ damage.
Weight loss approaches, when can it be difficult?
- Diet education and instruction
- Increase physical activity
- Behavior modification
- Weight loss may be more difficult if patient is using β-blockers beta blockers decrease heart rate-> decrease metabolic rates
Effect of sodium intake on Systolic blood pressure and urinary sodium excretion
For every increase of 100 mmol Na/d consumed-> increase in 3-6/0-3 mmHg SBP/DBP
the more you consume Na-> the more you will excrete
because of this Na regulation
sodium levels and excretion is tightly regulated
sodium excretion levels were used as a marker of sodium intake-> calculated the number of moles ingested
increases in blood pressure related to sodium excretion levels were noted
decrease in Na intake has a biggger impact on decreasing blood pressure in __ indivduals than in __ individuals
decrease in Na intake has a biggger impact on decreasing blood pressure in hypertensive indivduals than in normotensive individuals
What is the marker of sodium intake
number of moles pf sodium excreted
What is mean arterial pressure determined by?
cardiac output and total peripheral resistance
How is arterial blood pressure regulated?
Arterial blood pressure (BP) is regulated by the sympathetic nervous system, the renin–angiotensin–aldosterone system (RAAS), and renal function.
What does cardiac output equal to?
Cardiac output is equal to heart rate multiplied by stroke volume
What is heart rate dependent on?
Heart rate is dependent upon the balance between parasympathetic activity, which decreases heart rate, and sympathetic activity, which increases heart rate. The parasympathetic nervous system communicates with both the SA and AV nodes via the neurotransmitter acetylcholine, resulting in a decrease in heart rate. The sympathetic fibers, which are part of the cardiac accelerator nerves, stimulate the SA node and ventricles. When stimulated, these fibers release norepineph- rine, which causes an increase in heart rate
WHat does total peripheral resistance depend on?
The degree of resistance is dependent upon three factors: the radius of all arterioles, the length of the vessel, and the blood viscosity
Arteriolar radius is the most important factor in determining peripheral resistance.
What is the effect of Skeletal muscle activity on arteriolar radius?
Local metabolic controls in skeletal muscles may cause vasodilation, decrease resistance, and increase blood flow to those muscles in order to match metabolic needs.
The effect of Sympathetic activity and epinephrine on blood vessels
Sympathetic activity and epinephrine can cause vasoconstriction and increase resis- tance.
Vasopressin and angiotensin II effect on resistance and BP
Cause vasoconstriction-> decreased radius-> increased resistance
When there is a water deficit, vasopres- sin, released from the posterior pituitary gland, causes an increase in the reabsorption of water in the kidneys’ distal tubules. This will increase blood volume, thus increasing BP
What are the disease related death assocaited with high sodium intake?
High sodium intak eincreases the risk of CHD, CVD and ALL-cause mortality
this risk is higher with high sodium intake
Comparison of the effects of DASH-Sodium diet vs. standard American diet at 3 levels of sodium intake results
Movign from high intake to med intake of Na showed a smaller decrease in BP vs when goingr from med to low intake in both US and DASH diets
Wil the reduction of sodium intake always show an improvement in SBP?
Overall yes, btu individual response may vary- in non responders SBP may even increase