Hypertension Flashcards
Causes of secondary HTN
- Renovascular Disease/Renovascular
- Primary renal disease – eGFR + UA
- Polycystic Kidney Disease
- Endocrine causes such as:
○ Cushing’s Syndrome (primary pituitary adenoma or secondary due to drugs)
○ Conn’s Syndrome (primary hyperaldosteronism)
○ Pheochromocytoma (catecholamine-secreting adrenal tumour which causes triad of headache, palpitations, sweating)
○ Hyperthyroidism
○ Hyperparathyroidism - Coarctation of the aorta: hypertension in the upper extremities, brachial-femoral delay, low/unobtainable BP in the lower extremities
- Medications
○ Glucocorticoids
○ Contraceptives
○ NSAIDs
○ Antidepressants
○ Calcineurin inhibitors: Cyclosporin, tacrolimus
○ EPO - OSA - Sleep Study
Aldosterone:Renin Ratio
Aldosterone:Renin Ratio (ARR) is used to detect primary hyperaldosteronism in high risk, hypertensive patients
Aldosterone:Renin Ratio (ARR) • Primary Hyperaldosteronism – renin supressed; ratio increased >20 • Secondary Hyperaldosteronism – both are increased and decreased ratio (<10) ○ Renovascular disease ○ Diuretic therapy ○ Renin secreting tumour ○ Malignant hypertension ○ Coarctation of the aorta • Both supressed (non aldosterone mineralocorticoid excess): ○ Congenital adrenal hyperplasia ○ Exogenous mineralcorticoid ○ Cushing's syndrome ○ Liddle syndrome ○ Glucocorticoid resistance
Causes of renal artery stenosis
Most common
(A) Atherosclerotic disease 60-80%
Typically affects ostial/proximal portion of renal artery, can occur bilaterally
(B) Fibromuscular dysplasia 10-20%
- Non-atheromatous, non-inflammatory vascular condition
- Typically affects mid to distal renal artery, characteristic “string of beads” appearance on CTA
- Smoking, pregnancy associated with increased risk
- Renal arteries involved in 75 to 80% and extracranial cerebrovascular arteries (e.g., carotid and vertebral arteries) in 75 %
- Approximately two-thirds of patients have multiple arteries involved
Other Causes
- Renal artery embolism
- Dissection/thrombosis
- Post traumatic injury
- Occlusion from aortic stent graft
- External compression
- Systemic vasculitis
Atherosclerotic vs Fibromuscular Dysplasia RAS
Atherosclerotic RAS - Men: Women = 1:1 - Age > 55yo - Ostial/proximal renal artery - Ischaemic atrophy common - Total occlusion can occur - Less amenable to intervention RAS: Usually after 50 years and cholesterol plaque obstructs renal artery ( lesions usually within 2 cms of origin from aorta)
Fibromuscular Dysplasia - Women more affected (3:1 ratio to men) - Typical age 30-50, - Mid to distal renal artery - Ischaemic atrophy rare - Total occlusion rate - Amenable to intervention: good cure rates for HTN FMD: Commoner in women below 50 years age and unrelated to lipid status (lesions distal to proximal 2 cms of aortic origin of renal artery)
Difference between unilateral and bilateral renal artery stenosis
Unilateral Renal Artery Stenosis
- Increased BP
- Increased renin
- Normal volume state
Bilateral Renal Artery Stenosis
- Increased BP
- Normal renin
- Increased volume state
What is the pickering syndrome
Overtime, bilateral renal artery stenosis with volume overload leads to diastolic dysfunction and flash pulmonary oedema
When to suspect renovascular disease?
- Age of onset hypertension <30yrs or >55yrs
- Abrupt onset of hypertension
- Acceleration of previously stable blood pressure
- Hypertension refractory to appropriate 3-‐drug regimen
- Malignant hypertension
- Accelerated retinopathy
- Flash pulmonary oedema
- AKI with ACEI treatment
- Abnormal circadian rhythm with loss of nocturnal pressure fall
Consider in: – Young pts with HT – Severe or refractory HT – Increased Cr with ACE-I or ARB – Flash pulmonary oedema (more common with bilat RAS) – Known vascular disease and HT
• Rise in the serum creatinine by > 30 % within week of starting ACEI or ARB
• Severe hypertension in a patient with an unexplained atrophic kidney or
asymmetry in renal sizes of >1.5 cm
• Onset of severe and usually rapid hypertension after the age of 55
• A systolic-diastolic abdominal bruit that lateralizes to one side: low sensitivity (40 %) but very high specificity (99 %)
• Recurrent presentations with flash pulmonary oedema and refractory heart failure
• Keeps getting echocardiograms…troponins…diuresis…..keeps coming
back…..
• Please think about bilateral renal artery stenosis
What are other causes of elevated renin
- 15‐20% of people with essential hypertension will have elevated renin
- Renin can also be elevated with oestrogen intake, pregnancy, cortisol excess, from intra‐renal parenchymal disease, etc
- Renin levels fluctuate with posture, sympathetic tone, sodium intake and with the use of other drugs
Investigations for renovascular disease
- Renin, aldosterone levels
- Conventional angiography: gold standard
○ Generally reserved for confirmation and can proceed to subsequent intervention if required
○ Risks: AKI, cholesterol embolisation, contrast induced nephropathy, dissection, perinephric/groin haematoma - CT angiogram:
○ Most sensitive test, good pictures - Highly sensitive for FMD
○ Beware contrast load with renal impairment - MRI/A
Less sensitive for FMD - Doppler US
• velocity 3x the feeding artery significant
• Resistive indices: If >0.8 predicts poor outcome with angioplasty
Management of renovascular htn
- Blood pressure management with ACE/ARB
- Aggressive CVS risk factor modification
- Angioplasty + stenting - well established for fibromuscular dysplasia
Most patients with Conn’s Syndrome (primary hyperaldosteronism) present with? A. Hypertension and hyperkalaemia B. Hypertension and hypokalaemia C. Hypertension and normokalaemia D. Other irrelevant answer A E. Other irrelevant answer B
C. Hypertension and normokalaemia
Primary Aldosteronism
• Hypokalaemia and metabolic alkalosis (potassium normal in > 50% cases)
Treatment for renal artery stenosis
Unilateral RAS
- Medical therapy with ACE-I or ARB +/-thiazide
- Angioplasty for FMD
Bilateral RAS
- Traditionally avoid ACE-I or ARBs due to theoretical A-II dependence of glomeruli for filtration pressure but:
• Could try and watch Cr if increases >15-30% stop
- No evidence for stenting
What is essential HTN
Essential (cause unknown) 80-95% of HT
Risk factors • Salt • Obesity • Alcohol • Angiotensin excess • Sympathetic excess • FHx
58-year-old smoker presents with a new diagnosis of HT. His BP has been difficult
to control (190/110) despite amlodipine 10 mg/day and prazosin 5 mg bd.
On examination he has a loud abdominal bruit. His CT scan reveals a 1.5 cm left
adrenal mass. Lab investigations reveal:
Sodium 138 mmol/l [135-145]
Potassium 4.8 mmol/l [3.5 – 5.5]
Bicarb 23 mmol/l [22 – 28]
Creat 105 umol/l [< 120]
The most likely cause of his hypertension is:
A. Conns syndrome
B. phaeochromocytoma
C. essential hypertension
D. renal artery stenosis
E. Cushings syndrome
C. essential hypertension
A 65 y.o. man who weighs 74 kg has a serum creatinine of 125umol/l and the lab
provides an eGFR of 54.7ml/min. What is the most correct interpretation of these
results?
A. the GFR result is an underestimate because he is malnourished
B. the estimated GFR calculations are inaccurate in this range
C. he has significant renal impairment
D. the result should be confirmed with a 24 hour urine collection
E. he should be referred for renal biopsy
C. he has significant renal impairment
