3.1 Hypertension Flashcards
how do we work out mean arterial pressure?
cardiac output x total peripheral resistance
or
DBP + (SBP-DBP/3)
what 2 mechanisms do we use to regulate blood pressure?
autonomic sympatheitc activity
renin-angiotensin-aldosterone system
what are autocoids and how do they affect the vascular smooth muscle?
molecules that act as local hormones such as bradykinin and nitric oxide
act as vasodilators
what is the main determinant of resistance to flow?
radius of vessel
how does hypertension affect blood vessels?
causes remodelling, thickening and hypertrophy
what can cause vascular remodelling?
hypertension
local salt sensitivity
what are some of the pathological consequences of hypertrophy?
end organ damage - renal, peripheral vascular disease, aneurysm, vascular dementia, retinal disease
hypertensive heart disease - LVH and dilated heart failure
increased morbidity and mortality
linear relationship with coronary artery disease and stroke
what is hypertension?
an elevation in blood pressure that is associated with an increase in risk of some harm
greater than 140/90mmHg
what is the most common cause of hypertension?
essential/primary/idiopathic hypertension
how do we increase diagnoses of hypertension?
- Screening those at risk - often hypertensive patients are asymptomatic
- Increasing public awareness of risk factors
- Appropriate lifestyle changes to limit risk – no immediate gain presents a challenge.
- Reliable measurements based on clinical guidelines
- Regular monitoring and refinement of medication
how do we measure blood pressure to diagnose hypertension?
- Sitting, relaxed and arm is supported. Cuff placed at the level of the heart
- Both arms, >15 mmHg difference repeat measurement and use arm with higher reading
- Measurements over period of visits +/- ABPM/HBPM
when is emergency treatment for hypertension advised?
> 180 SBP or 120 DBP + clinical signs (retinopathy/headaches/seizures)
what are the target blood pressures in hypertensives?
- 140/90 < 80 years old including type II diabetes
- 150/90 > 80 years old
- 135/85 type 1 diabetes
what is the desired BP?
120/80mmHg
what is stage 1 hypertension?
Clinic blood pressure ranging from 140/90 mmHg to 159/99 mmHg and subsequent ABPM daytime average or HBPM average blood pressure ranging from 135/85 mmHg to 149/94 mmHg.
what is stage 2 hypertension?
Clinic blood pressure of 160/100 mmHg or higher but less than 180/120 mmHg and subsequent ABPM daytime average or HBPM average blood pressure of 150/95 mmHg or higher.
what is stage 3 or severe hypertension?
Clinic systolic blood pressure of 180 mmHg or higher OR clinic diastolic blood pressure of 120 mmHg or higher.
what is the BP range of prehypertension?
> 120/80 <140/90 mmHg
what is the advice given to patients that are prehypertensive?
- Promotion of regular exercise
- Modified healthy/balanced diet
- Reduction in stress and increased relaxation
- Limited/reduced alcohol intake
- Discourage excessive caffeine consumption
- Smoking cessation
- Reduction in dietary sodium
name some primary hypertension therapeutic drugs?
• Angiotensin converting enzyme (ACE) inhibitors (ACEi)
Angiotensin (AT1) receptor blockers (ARBs)
• Calcium channel blockers (CCBs)
• Diuretics – thiazide and thiazide-like
where is ACE predominantly found?
on the luminal surface of capillary endothelium in the lungs
what are the main receptors of angiotensin-II?
AT1 (vasoconstriction)
AT2 (opposes action of AT1)
what are the main actions of AT-II?
vasoconstriction
stimulation of aldosterone
cardiac and vascular muscle cell growth
ADH release form posterior pituitary
what are the main actions of ACEi?
A reduction in Angiotensin-II activity, resulting in
vasodilation (↓ peripheral resistance →↓afterload)
reduction in aldosterone release (↑Na + H2O excretion)
reduced vasopressin (ADH) release (↑ H2O excretion)
reduced cell growth and proliferation
how can AT-II be produced from AT-I independently of ACE?
via chymases
how do ACEi cause vasodilation?
- reduce angiotensin-II activity that would have caused vasoconstriction
- Bradykinin is a substrate for ACE. ACEi increase the effects of bradykinin causing vasodilation via NOS/NO and PGI2
give some examples of ACEi
lisinopril
ramipril
what are the ADRs of ramipril?
hypotension dry cough hyperkalaemia cause or worsen renal failure angioedema
what are the contraindications of ACEis?
Renal artery stenosis, AKD, pregnancy, (CKD - caution), idiopathic angioedema
what are the important drug reactions of ACEis?
increasing K+ drugs, NSAIDs, other antihypertensive agents
give some examples of ARBSs/ AT1 receptor blockers?
candesartan
lasartan
what are some of the ADRs of ARBs?
Hypotension!
hyperkalaemia (low aldosterone ↑K+) cause or worsen renal failure