14 Hypertension Flashcards
Q: How is blood pressure distributed in a population? Equation?
A: BP distribution is unimodal ((of a statistical distribution) having one maximum) and any distinction between normal and abnormal is arbitrary
BP= CO x PVR (peripheral vascular resistance)
Q: Define hypertension. What does it mean to have prehypertension?
A: the level of blood pressure above which investigation and treatment do more good than harm
implies that eventually you’ll get hypertension- not for certain but likely
Q: What’s the updated main emphasis when it comes to hypertension? Means that?
A: Main change is emphasis on ambulatory blood pressure and home blood pressure monitoring vs “office” BP:
Threshold 5-10 mm Hg lower
Q: What happens to blood pressure with age? Pulse pressure? Who’s expected to have hypertension? (2)
A: Mean BP rise with age
Pulse pressure rises with age
The majority of people >60y would be expected to be hypertensive by current definitions, almost everyone hypertensive by >80y
Q: What is pulse pressure? How is it affected by age? Why? (2) Where is this pattern seen? Main factor?
A: gap between systolic and diastolic
increases
- older=increased systolic
- older (after 50 yrs)= slowly decreasing diastolic
not everywhere, seen in northern europe/UK/US
thought to be salt, associated with possible driving factor in primary hypertension
Q: What are the 2 classes of hypertension? Most common? Include some causes (5).
A: 95%= primary (or essential) hypertension
-no identifiable cause
5%= secondary hypertension
-identifiable cause
eg
- Renal disease, including renal artery stenosis,
- Tumours secreting aldosterone (Conn’s syndrome)
- Tumour secreting catecholamines (phenochromocytoma)
- Oral contraceptive pill
- Pre-eclampsia (high bp and high protein in urine)/pregnancy associated hypertension
Q: What’s the relationship between systolic BP and risk of stroke? There is no? Relationship also seen with? (2)
A: The relationship between BP and risk is exponential (log linear) and there is no threshold for risk.
Similar relationships have been shown for BP and coronary heart disease and other cardiovascular disease.
Q: 4 environmental factors of hypertension.
A: -Dietary salt (sodium)
- Obesity / overweight, lack of exercise
- Alcohol (excessive)
- Pre-natal environment (~birthweight)
Q: How can the prenatal environment lead to increases risk of getting diseases? Eg? (2)
A: eg those with low birth weight is likely due to having a mother that was malnourished during the pregnancy
high blood pressure, diabetes
Q: What are the 2 genetic types of hypertension causes? Common? 2 examples for first type. Describe the second. (2)
A: monogenic-rare (single gene causes) <1%
complex polygenic- common
Monogenic disease causes <1% of hypertension
- Liddle’s syndrome = Mutation in amiloride-sensitive tubular epithelial Na channel
- Apparent mineralocorticoid excess = Mutation in 11b-hydroxysteroid dehydrogenase
Complex polygenic causes
- Multiple genes with small effects (positive and negative)
- Interactions with sex, other genes, environment
Q: Typically, what is established hypertension associated with? (5) All?
A: - Increased total peripheral resistance
- Reduced arterial compliance (higher pulse pressure)
- Normal cardiac output
- Normal blood volume/extracellular volume
- Central shift in blood volume = secondary to reduced venous compliance
pattern in majority of adults with hypertension
Q: What accounts for the elevated PVR in hypertension? (3) Include causes.
A: peripheral vascular resistance
- Active narrowing of arteries - vasoconstriction (probably short-term/ may be driven by sympathetic NS/ renin-angiotensin system)
- Structural narrowing of arteries - growth and remodelling (walls get thicker and lumen thinner)
- Loss of capillaries - rarefaction (may be protective measure against high blood pressure)
Q: What is isolated systolic hypertension? Parameters? (2) Age? Cause? Result? What does it not fit with?
A: leading cause of hypertension in lots of western countries
Systolic BP ≥ (> or equal to) 140
diastolic BP ≤ (< or equal to) 90
Condition of people over age 60 (more common as age increases) - get larger gap between systolic and diastolic
Mechanism thought to be:
- Due to increasing stiffness of medium/large arteries
- Pulse wave reflected and is greater (amplified) by the time it reaches brachial artery (peripheral, where measured) INSTEAD OF being absorbed/dampened by blood vessels
basic pattern of cardiac output - peripheral resistance pattern since this isn’t really more resistance-> the resistance if measured is the same, it’s just the pulse wave that is being affected
Q: What are the 3 candidate causes of primary hypertension? Describe (1,2,1).
A: Kidney
-Best evidence especially in relation to salt intake: some individuals kidney= unable to handle salt intake and retains it and therefore retains water too
Sympathetic nervous system
- (in younger people)
- Evidence linking high sympathetic activity to the development of hypertension
Endocrine/paracrine factors
-Inconsistent evidence
Q: What’s the kidneys role in BP? What can impaired renal function cause? 2 examples of conditions. Visually?
A: The kidney exerts a major influence on BP through regulation of sodium/water/extracellular fluid volume
Impaired renal function or blood flow is the commonest secondary cause of hypertension (e.g. renal parenchymal disease, renal artery stenosis)
kidneys shrink
