12 - Hypertension Flashcards
What is congestive heart failure?
The inability of the heart to adequately pump blood at normal filling pressures.
What is hypertension?
- the level of blood pressure above which investigation and treatment do more harm than good
- defined as BP >140/90mmHg
What is the epidemiology of hypertension?
- leading global cause of death (higher BP = higher mortality risk)
- affects 1 billion people worldwide
- distribution is unimodal
- mean BP rises with age (no. of people diagnosed with hypertension increases with age)
What are the environmental risk factors of hypertension?
- dietary salt intake
- obesity
- alcohol
- pregnancy
- lack of exercise
- alcohol consumption
What is the aetiology of primary and secondary hypertension?
- primary/essential: unidentifiable cause (genetic or environmental)
- secondary: identifiable cause (renal disease, tumours, the pill)
What causes an elevated TPR?
- capillary loss (rarefaction)
- structural narrowing of arteries (growth and remodelling)
- active narrowing of arteries (vasoconstriction)
What are the haemodynamics of blood pressure?
- primary: increased TPR, decreased arterial compliance, normal CO and blood volume, central shift in volume
- secondary: decreased venous compliance
What is isolated systolic hypertension and some features of it?
- systolic BP >140mmHg, diastolic BP <90mmHg
- condition of people over 60
- due to increasing stiffness of medium/large arteries
- TPR doesn’t increase
What is the pathology of primary hypertension?
- over-activity of SNS
- endocrine/paracrine factors
- impaired renal function causes decreased Na+ excretion
What are the lifestyle modifications to treat hypertension?
- weight loss
- exercise
- healthy eating
- lowered alcohol intake
What 4 types of drugs are used to treat hypertension, with examples?
- diuretics: benzoflumethiazide and thiazide
- beta blockers: propanolol
- calcium channel blockers: amlodipine
- ACE inhibitors: ramipril
How do diuretics operate to reduce hypertension?
- act on DCT (unknown mechanism)
How do beta blockers operate to reduce hypertension?
- block β1 receptors in heart to reduce rate and force of contraction
- block β1 receptors in kidney to reduce renin secretion and RAAS activity
How do calcium channels operate to reduce hypertension?
- major: in VSMC reduce Ca2+ influx, reducing actin myosin cross bridges
- minor: in heart inhibits Ca2+ influx and reduces contractility
How do ACE inhibitors operate to reduce hypertension?
- prevent angiotensin ii formation
- stops AGTii functions leading to increased BP
