Hypertension: Pathophysiology Flashcards
What is BP a good predictor of?
Cardiovascular risk
What is the cause of essential/primary HTN?
Unknown
What is labile HTN?
How is it diagnosed?
Intermittent hypertension with nocturnal dip
Diagnosed using 24 hour monitoring as there are times througout the day where the BP reading will be normal, can be missed in clinic.
What is non-dipping HTN?
How does this affect CV risk?
Hypertension without nocturnal dip
Epidemiologically have a higher risk of CV event than HTN with nocturnal dip
List some causes of secondary HTN
‘ROPE’
- Renal disease: renal artery stenosis; CKD
- Obesity and Obstructive sleep apnoea
- Pregnancy, Pre-eclampsia
- Endocrine: hyperaldosteronism (Conn’s syndrome): adrenal adenoma/adrenal bilateral hyperplasia
Also:
- Aortic coarctation
- Phaeochromocytoma
- Cushing’s disease
- Hyperparathyroidism
What can cause primary hyperaldosteronism (Conn’s syndrome)?
- Adrenal adenoma (50% of cases)
- Adrenal bilateral hyperplasia (50% of cases)
What is the first line treatment for Conn’s syndrome?
What investigations should be used?
Which blood results are diagnostic of primary Conn’s syndrome?
Which blood results would suggest secondary hyperaldosteronism?
Treatment:
- 1st line: Spironolactone +/- surgery (only for adenoma)
Inv:
- U&Es
- Plasma aldosterone supine and standing
- Plasma renin activity supine and standing
- (raised aldosterone will be matched by decreased renin- diagnostic of Conn’s syndrome)
- High aldosterone and high renin = secondary hyperaldosteronism caused by other factors
- CT scan for ?adenoma
- Adrenal venous sampling (measures aldosterone from the adrenal veins to see where the increased aldosterone is coming from)
Define resistant HTN
What is it usually caused by?
When a patient’s BP is not controlled to recommended levels despite treatment with an appropriate combination of 3 drug therapies prescribed at the maximum recommended and/or tolerated doses.
Usually caused by systolic HTN
What are the causes/risk factors for resistant HTN?
- Age (>75)
- Obesity
- Female
- Black/Afro-caribbean ethnicity
- High baseline BP
- Duration of uncontrolled HTN
- Diabetes
- Atherosclerosis
- Aortic stiffening
- High sodium and/or alcohol intake
- Drugs
Which drugs can precipitate HTN?
- NSAIDs
- Sympathomimetic amines (e.g. phenylpromanomines)
- Methylxanthines
- Cyclosporin
- Cocaine
- Nicotine
- Erythropoietin
- Oestrogen/progesterone combination pill & HRT
- Venlafaxine
What are the non-pharmacological methods to reduce HTN risk?
- Reduce sodium intake
- Reduce alcohol intake
- Increase exercise
- Weight loss
- High potassium diet
What are the main classes of drugs used to treat HTN?
- ACE-inhibitors
- Angiotension II receptor blockers (ARBs)
- Thiazide-like diuretics
- Calcium channel blockers
- B-adrenoceptor blockers
- Renin inhibitors
How is hypertension classified?
- Essential or primary hypertension
- Secondary hypertension
- Pseudo resistant hypertension
- Resistant or refractory hypertension
- HTN in pregnancy
- Paediatric HTN
How is hypertension diagnosed (according to NICE guidelines)
Diagnosis based on high BP reading and confirmed by reading outside of clinic (i.e. ambulatory monitoring at home)
Clinic BP >140/90 and at home BP > 135/85
What is the most common cause of renal artery stenosis?
Which patients are at risk of this?
How is it diagnosed and treated?
Most commonly caused by atheroma, can be genetic (fibromuscular dysplasia) (more common in females and younger patients)
- Present in 50% of patients with clinical vascular disease
- Common when multiple CV risk factors present
Diagnosed with renal angiography (MRI angiogram)
Treated with angioplasty and balloon
What should be suspected in younger patients, particularly females, with severe resistant hypertension?
Fibromuscular dysplasia causing renal artery stenosis
How is phaeochromocytoma investigated and diagnosed?
How is it treated?
- Plasma adrenaline and noradrenaline (raised well above upper limit of normal)
- Urine (24hr) adrenaline and noradrenaline (raised well above upper limit of normal)
- Urine VMAs (metabolites of catecholamines raised well above upper limit of normal)
- 3 consecutive tests as can be normal in between symptomatic episodes
- I-123 M.I.B.G scan (isotopes taken up by chromaffin in adrenal medulla)- will show increased uptake.
- Whole body scan as phaeochromocytoma can be caused by tumours of neural ganglions also.
Treatment:
- Phenoxybenzamine (alpha blocker) initially
- Atenolol (B blocker) after alpha blocker
- Surgery to remove tumour (most are benign but 10% become malignant)
What are the signs and symptoms of phaeochromocytoma?
Signs:
- Intermittent severe HTN
Symptoms:
- Hot flushes
- Headaches
- Blurred vision
- Chest pain
- Palpitations
- Sweating attacks
What is a possible long term complication of phaeochromocytoma?
Cardiomyopathy
What condition will occur if both adrenal glands are removed?
In what circusmtances can both adrenal glands be removed?
Can be removed if bilateral phaeochromocytoma
Results in Addison’s disease
What can cause pseudo-resistant HTN?
- White coat syndrome
- Inaccurate measurement (e.g. wrong cuff size)
- Poor adherence to medication
Withdrawal from which types of drugs can cause HTN?
Beta blockers
Alpha antagonists
Opioids
Ethanol
Calcium antagonists
