Admit for intravenous therapy, lowering mean arterial pressure by at most 20% to 25% in the first hour. This patient has a hypertensive emergency, defined by severe blood pressure elevation (> 180/120 mmHg) complicated by acute target organ damage (hypertensive encephalopathy, acute renal impairment, and Grade IV hypertensive retinopathy with papilloedema). Management mandates immediate admission to an intensive care or high-dependency unit and continuous intravenous antihypertensive titration (e.g., sodium nitroprusside or labetalol). The overarching therapeutic principle is controlled, gradual reduction: the mean arterial pressure (MAP) must be decreased by no more than 20% to 25% over the first hour, followed by gradual reduction toward 160/100 mmHg over the subsequent 2 to 6 hours. Rapid or excessive reduction must be avoided because chronically shifted cerebral and renal vascular autoregulation curves would cause hypoperfusion, leading to cerebral watershed infarction or worsening acute kidney injury. Sublingual nifedipine is dangerous and contraindicated.

Q: A 36-year-old woman is evaluated for paroxysmal episodes of severe throbbing headaches, profuse sweating, and palpitations that occur two to three times per week. Her blood pressure during an episode was recorded as 210/115 mmHg. Twenty-four-hour urinary fractionated metanephrines are markedly elevated at five times the upper limit of normal, and an abdominal MRI reveals a 3.5 cm hypervascular right adrenal mass. Surgical resection is scheduled. Which of the following pharmacological management plans is essential prior to surgery?

Commence alpha-adrenergic blockade first, adding a beta-blocker only after adequate vasodilation. In patients with phaeochromocytoma, surgical resection carries a high risk of intraoperative catecholamine release and catastrophic hypertensive crisis. Preoperative medical preparation requires complete alpha-adrenergic receptor blockade for at least 10 to 14 days before surgery, typically using the non-competitive, irreversible alpha-blocker phenoxybenzamine (or selective competitive alpha-1 blockers like prazosin or doxazosin). A critical pharmacological rule is that alpha-blockade must always precede beta-blockade. If a beta-blocker is administered alone or prematurely, it blocks vasodilatory beta-2 receptors in skeletal muscle vascular beds while leaving catecholamine stimulation of alpha-1 vascular receptors unopposed. This produces intense, unopposed peripheral vasoconstriction and precipitates acute coronary ischaemia, pulmonary oedema, and lethal hypertensive crisis. Beta-blockers are added only after adequate alpha-blockade is established to treat reflex tachycardia.

Q: A 66-year-old retired tradesman with a 40 pack-year smoking history presents with cramping pain in his right calf that consistently develops after walking 200 metres on level ground and resolves completely within 3 minutes of standing still. He has no pain at rest and no skin breakdown. Physical examination reveals diminished right dorsalis pedis and posterior tibial pulses, normal femoral pulses, and mild elevation pallor. Resting ankle-brachial pressure index (ABPI) is 0.68 in the right leg and 0.96 in the left leg. Which of the following is the most appropriate initial management approach?

Implement smoking cessation, high-intensity statin, antiplatelet therapy, and supervised exercise. This patient has typical intermittent claudication secondary to moderate peripheral arterial disease (PAD), supported by an ankle-brachial pressure index (ABPI) of 0.68. First-line management for stable claudication without critical limb-threatening ischaemia (no rest pain, ulcers, or gangrene) is comprehensive medical therapy and lifestyle modification. This encompasses mandatory, supported smoking cessation, high-intensity statin therapy (e.g., atorvastatin 80 mg daily) to stabilize atherosclerotic plaques, single antiplatelet therapy (aspirin 100 mg or clopidogrel 75 mg daily) to prevent systemic cardiovascular events, and enrollment in a structured, supervised exercise therapy (SET) program for at least 12 weeks. Supervised walking promotes angiogenesis, develops collateral arterial pathways, and markedly extends pain-free walking distance. Revascularization (angioplasty or surgical bypass) is reserved for patients with critical limb-threatening ischaemia (ABPI under 0.40, rest pain, tissue necrosis) or those with debilitating claudication that fails conservative management.

Key Takeaways

Hypertensive emergency involves acute target-organ injury, not an elevated reading alone.
An ankle–brachial index below 0.9 supports peripheral arterial disease.
Rest pain, ulceration or gangrene requires urgent vascular assessment.

Last updated: October 2026

Secondary Hypertension: Diagnostic Evaluation and Management

Secondary hypertension accounts for approximately $5\%\text{ to }10\%$ of adult hypertension. It should be investigated when clinical "red flags" appear: age of onset $< 30\text{ years}$ , abrupt or severe onset, resistant hypertension (blood pressure uncontrolled despite full doses of three concurrent antihypertensives including a diuretic), or unprovoked hypokalaemia.

Clinical comparison: Secondary Hypertension Etiologies, Clinical Clues, and Investigations

Renal Parenchymal Disease: Pathophysiological Mechanism: Glomerular/tubulointerstitial loss leading to salt/water retention; Clinical Presentation & Clues: Elevated creatinine, microscopic haematuria, proteinuria; First-Line Screening Test: Urinary albumin-to-creatinine ratio (uACR), eGFR, urinalysis; Confirmatory Diagnostic Test: Renal ultrasound (bilateral small, echogenic kidneys)
Renal Artery Stenosis: Pathophysiological Mechanism: Renal hypoperfusion stimulating the renin-angiotensin cascade; Clinical Presentation & Clues: Atherosclerotic in elderly smokers; Fibromuscular Dysplasia in young females; acute creatinine rise $> 30\%$ post-ACEi; First-Line Screening Test: Renal duplex Doppler ultrasound; Confirmatory Diagnostic Test: CT or Magnetic Resonance Angiography ("string-of-beads" in FMD)
Primary Aldosteronism: Pathophysiological Mechanism: Autonomous adrenal aldosterone secretion suppressing renin; Clinical Presentation & Clues: Resistant hypertension; unprovoked or diuretic hypokalaemia; muscle weakness; First-Line Screening Test: Morning paired Aldosterone-to-Renin Ratio (ARR); Confirmatory Diagnostic Test: Saline infusion test or fludrocortisone test; adrenal CT & adrenal venous sampling
Phaeochromocytoma: Pathophysiological Mechanism: Paroxysmal catecholamine hypersecretion by chromaffin tumour; Clinical Presentation & Clues: Classic triad: episodic headaches, profuse sweating, tachycardia; First-Line Screening Test: 24-hour urinary fractionated metanephrines or plasma free metanephrines; Confirmatory Diagnostic Test: Abdominal MRI / CT; MIBG or Ga-68 DOTATATE PET scan
Hypercortisolism: Exclude exogenous glucocorticoids first. Validated initial tests include overnight low-dose dexamethasone suppression, late-night salivary cortisol or urinary free cortisol. Confirmation and localisation are separate specialist steps; high-dose dexamethasone is not an initial screening test.
Obstructive sleep apnoea: Ask about snoring, witnessed pauses, daytime sleepiness and resistant hypertension. Diagnosis uses sleep testing and clinical context; an apnoea–hypopnoea index of at least 5 with relevant symptoms can meet criteria, so 15 is not the only diagnostic threshold.

Essential Pharmacological Rule for Phaeochromocytoma

In patients with suspected or confirmed phaeochromocytoma, alpha-adrenergic blockade (e.g., phenoxybenzamine) must always precede beta-adrenergic blockade. Initiating a beta-blocker alone blocks beta-2-mediated vasodilation while leaving alpha-1-mediated vasoconstriction completely unopposed, precipitating an extreme, potentially fatal hypertensive crisis. Beta-blockers are added only after several days of effective alpha-blockade to control reflex tachycardia.

Hypertensive Emergencies vs Urgencies

Hypertensive Emergency: Severe elevation in blood pressure (typically $> 180/120\text{ mmHg}$ $> 180/120 mmHg$ ) associated with acute, life-threatening target organ damage:
- Neurological: Hypertensive encephalopathy, acute ischaemic stroke, intracranial haemorrhage.
- Cardiovascular: Acute aortic dissection, acute coronary syndrome, acute pulmonary oedema.
- Renal: Acute kidney injury with haematuria and proteinuria.
- Ophthalmological: Advanced Grade IV hypertensive retinopathy (papilloedema, flame haemorrhages, cotton-wool spots).
- Obstetric: Severe pre-eclampsia or eclampsia.
- Management: Requires admission to an intensive care or high-dependency unit, continuous intra-arterial blood pressure monitoring, and titratable intravenous agents (e.g., sodium nitroprusside, labetalol, hydralazine, glyceryl trinitrate).
- The 25% Rule: Blood pressure must be lowered gradually: decrease mean arterial pressure (MAP) by no more than 20% to 25% over the first hour, and then toward $160/100\text{ mmHg}$ over the subsequent 2 to 6 hours. Precipitous reduction impairs autoregulation and precipitates ischaemic stroke or myocardial infarction.
- Critical Exceptions to the 25% Rule:
  1. Acute Aortic Dissection: Requires rapid reduction of SBP to $< 120\text{ mmHg}$ and heart rate to $< 60\text{ bpm}$ within 20 minutes (using IV beta-blockers such as esmolol or labetalol first, followed by vasodilators).
  2. Acute Ischaemic Stroke: Blood pressure is not lowered unless $> 220/120\text{ mmHg}$ (permissive hypertension), or $> 185/110\text{ mmHg}$ if the patient is eligible for intravenous thrombolysis.
Hypertensive Urgency: Severe elevation in blood pressure without acute target organ damage. Does not require intravenous therapy or emergency hospital admission. Managed in the outpatient setting with oral agents (e.g., intensifying maintenance therapy) with blood pressure brought down safely over 24 to 48 hours. Sublingual nifedipine is strictly contraindicated due to unpredictable precipitous hypotension and associated stroke and death.

Peripheral Arterial Disease (PAD)

Peripheral arterial disease results from systemic atherosclerosis causing progressive narrowing of lower extremity arteries:

Intermittent Claudication: Exertional muscle pain, aching, or fatigue (most commonly in the calf, but may involve the thigh or buttock) that is reproducible at a fixed walking distance and resolves completely within 2 to 5 minutes of standing still.
Chronic Limb-Threatening Ischaemia (CLTI): Severe manifestation defined by ischaemic rest pain lasting $> 2\text{ weeks}$ , non-healing ulcerations, or gangrene. Rest pain is classically worse at night when recumbent due to loss of gravitational hydrostatic pressure and improves when the patient hangs the leg over the edge of the bed.
Physical Examination: Absent or diminished pulses (femoral, popliteal, posterior tibial, dorsalis pedis), femoral bruits, cool pale extremities, trophic changes (hair loss, brittle nails, shiny thin skin), and Buerger test (marked elevation pallor followed by dependent rubor due to reactive hyperaemia). Arterial ulcers are deep, painful, "punched-out" lesions with necrotic bases, typically located over pressure points (tips of toes, lateral malleolus).

Ankle-Brachial Pressure Index (ABPI) Interpretation

ABPI is calculated by dividing the highest systolic pressure measured at each ankle (dorsalis pedis or posterior tibial) by the highest brachial systolic pressure using a Doppler ultrasound probe:

ABPI: At most 0.90 supports PAD; 0.91–0.99 is borderline, 1.00–1.40 is usually normal and above 1.40 suggests incompressibility. In diabetes/CKD, toe pressures and other vascular assessment may be needed. Rest pain, ulceration and gangrene require urgent assessment regardless of a reassuring number.

Comprehensive Management

Risk Factor Modification: Absolute, complete smoking cessation (the single most potent intervention to halt limb amputation); high-intensity statin therapy (atorvastatin $80\text{ mg}$ daily); blood pressure control ( $< 130/80\text{ mmHg}$ ); and tight glycaemic control.
Antiplatelet Monotherapy: Aspirin $100\text{ mg}$ daily or clopidogrel $75\text{ mg}$ daily (clopidogrel showed slight superiority in the CAPRIE trial).
Supervised Exercise Therapy (SET): The first-line conservative intervention for claudication. Involves structured treadmill walking to near-maximal pain for $30\text{ to }45\text{ minutes}$ , at least 3 times weekly for a minimum of 12 weeks, which stimulates collateral circulation.
Revascularization: Indicated for patients with CLTI (rest pain, tissue loss) or severe, lifestyle-limiting claudication refractory to medical therapy. Modalities include endovascular angioplasty/stenting or surgical bypass grafting (e.g., autologous saphenous vein femoropopliteal bypass).

Primary references (checked 7 October 2026): Australian CVD risk guideline.

Test Your Knowledge

A 56-year-old woman presents to the emergency department with a severe, throbbing headache, blurred vision, and mild confusion. On physical examination, her blood pressure is 226/132 mmHg and heart rate is 88 beats per minute. Fundoscopic examination reveals bilateral flame-shaped retinal haemorrhages, soft exudates, and distinct papilloedema. Neurological examination reveals no focal motor or sensory deficits. Serum creatinine is 165 micromol/L (baseline: 75 micromol/L). Which of the following principles should guide the initial pharmacological reduction of her blood pressure?

Administer sublingual nifedipine to rapidly restore blood pressure to normal within 30 minutes

Admit for intravenous therapy, lowering mean arterial pressure by at most 20% to 25% in the first hour

Administer high-dose intravenous loop diuretics to drive systolic blood pressure below 120 mmHg

Provide intensified oral dual antihypertensives and arrange outpatient review in forty-eight hours

Test Your Knowledge

A 36-year-old woman is evaluated for paroxysmal episodes of severe throbbing headaches, profuse sweating, and palpitations that occur two to three times per week. Her blood pressure during an episode was recorded as 210/115 mmHg. Twenty-four-hour urinary fractionated metanephrines are markedly elevated at five times the upper limit of normal, and an abdominal MRI reveals a 3.5 cm hypervascular right adrenal mass. Surgical resection is scheduled. Which of the following pharmacological management plans is essential prior to surgery?

Commence beta-adrenergic blockade first, adding an alpha-blocker only if heart rate exceeds 100

Initiate high-dose intravenous hydrocortisone and oral spironolactone two weeks prior to surgery

Commence alpha-adrenergic blockade first, adding a beta-blocker only after adequate vasodilation

Prescribe oral clonidine monotherapy and restrict dietary sodium intake to prevent volume expansion

Test Your Knowledge

A 66-year-old retired tradesman with a 40 pack-year smoking history presents with cramping pain in his right calf that consistently develops after walking 200 metres on level ground and resolves completely within 3 minutes of standing still. He has no pain at rest and no skin breakdown. Physical examination reveals diminished right dorsalis pedis and posterior tibial pulses, normal femoral pulses, and mild elevation pallor. Resting ankle-brachial pressure index (ABPI) is 0.68 in the right leg and 0.96 in the left leg. Which of the following is the most appropriate initial management approach?

Perform urgent surgical bypass grafting of the right superficial femoral artery within two weeks

Prescribe systemic oral corticosteroid therapy combined with high-dose subcutaneous low-molecular-weight heparin

Reassure the patient that the symptoms are benign and advise complete avoidance of physical exertion

Implement smoking cessation, high-intensity statin, antiplatelet therapy, and supervised exercise

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