2.4 Hypertension, Vascular & Pericardial Diseases

2.4 Hypertension, Vascular & Pericardial Diseases

Hypertension, aortic pathology, vascular disease, and pericardial conditions are high-yielding topics for the MRCPI Part I examination. Mastery of diagnostic thresholds, secondary screening algorithms, hypertensive emergency protocols, and pericardial diagnostic criteria is required.

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Systemic Hypertension

Diagnostic Thresholds & Categories

Diagnosis requires multiple office BP readings on separate occasions or out-of-office BP monitoring:

• Office BP Threshold: >=140/90 mmHg.
• Ambulatory BP Monitoring (ABPM): Daytime mean >=135/85 mmHg; 24-hour mean >=130/80 mmHg.
• Home BP Monitoring (HBPM): Mean >=135/85 mmHg.

Pharmacological Management Algorithm (ESC/ESH Guidelines)

• Step 1 (Initial Dual Therapy): Single-Pill Combination (SPC) of an ACE inhibitor or ARB + Calcium Channel Blocker (CCB) OR Thiazide/Thiazide-like Diuretic (Indapamide or Chlorthalidone preferred over Hydrochlorothiazide). Monotherapy is reserved for low-risk Grade 1 hypertension or frail elderly patients.
• Step 2 (Triple Combination): Single-Pill Combination of ACEi/ARB + CCB + Thiazide-like Diuretic.
• Step 3 (Resistant Hypertension): Confirmed when target BP (<130/80 mmHg) is not achieved despite triple therapy at maximum tolerated doses. Add Spironolactone 25–50 mg daily (or Amiloride, Doxazosin, or Beta-blocker if potassium >4.5 mmol/L or eGFR <30 mL/min/1.73m2).

Secondary Hypertension Screening Indications

Young patients (<40 years), sudden onset, resistant hypertension, or severe Grade 3 presentation warrant workup:

• Renovascular Hypertension: Atherosclerotic renal artery stenosis (elderly) or Fibromuscular Dysplasia (young females). Diagnostic test: Renal Doppler Ultrasound or CT Angiography.
• Primary Aldosteronism (Conn's Syndrome): Unexplained hypokalemia, hypertension. Screening: Aldosterone-to-Renin Ratio (ARR >30); confirmatory test: Saline suppression test.
• Pheochromocytoma: Paroxysmal HTN, headache, palpitations, diaphoresis. Diagnostic test: Plasma free metanephrines or 24-hour urinary fractionated metanephrines.
• Coarctation of the Aorta: Radio-femoral delay, upper limb SBP > lower limb SBP by >20 mmHg. Rib notching on chest X-ray.

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Hypertensive Crises

• Hypertensive Urgency: Severe BP elevation (SBP >180 mmHg or DBP >120 mmHg) without acute target organ damage. Treated with oral antihypertensives (Captopril, Labetalol, or Amlodipine) over 24–48 hours in an outpatient setting.
• Hypertensive Emergency: Severe BP elevation accompanied by acute target organ damage (hypertensive encephalopathy, acute aortic dissection, acute coronary syndrome, acute pulmonary edema, pre-eclampsia/eclampsia).
• Treatment Protocol: Requires ICU admission and IV titratable continuous infusions (Labetalol, Nicardipine, Sodium Nitroprusside, Esmolol). Reduce SBP by a maximum of 25% within the first hour, then to 160/100 mmHg over 2–6 hours.
• EXCEPTIONS TO SLOW BP REDUCTION:
  1. Acute Aortic Dissection: Rapid reduction of SBP to <120 mmHg and HR <60 bpm within 20 minutes.
  2. Acute Ischemic Stroke: BP lowered only if SBP >220 mmHg or DBP >120 mmHg (or >185/110 mmHg if thrombolysis planned).

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Acute Aortic Syndromes

Acute aortic syndromes comprise Aortic Dissection, Intramural Hematoma (IMH), and Penetrating Atherosclerotic Ulcer (PAU). Aortic dissection involves a tear in the aortic intima allowing blood to enter the media, creating a false lumen.

Classification Systems

• Stanford Classification:
  • Type A: Involves the ascending aorta (proximal to left subclavian artery). Accounts for 60–70% of cases.
  • Type B: Involves only the descending aorta distal to the left subclavian artery.
• DeBakey Classification: Type I (Ascending + Descending), Type II (Ascending only), Type III (Descending only).

Clinical Features & Imaging

• Sudden onset of severe, sharp, "tearing" or "ripping" chest pain radiating to the interscapular back. Pulse deficits, asymmetric blood pressure (>20 mmHg difference between arms), aortic regurgitation murmur, or neurological deficits.
• Diagnostic Gold Standard: CT Aortic Angiography (sensitivity and specificity >98%). Transesophageal Echocardiography (TEE) indicated if hemodynamically unstable.

Management Strategy

• Medical Stabilization: Intravenous Beta-blockers (Labetalol or Esmolol) immediately initiated to reduce aortic wall stress ($dP/dt$). Target SBP 100–120 mmHg and HR <60 bpm. Add IV Vasodilators (Nitroprusside) only after heart rate control is achieved.
• Stanford Type A: Emergency Open Surgical Repair (Dacron graft replacement +/- aortic valve repair/Bentall procedure) due to high risk of aortic rupture, cardiac tamponade, or acute coronary occlusion.
• Stanford Type B: Uncomplicated Type B managed medically with strict BP control. Complicated Type B (end-organ malperfusion, rupture, refractory pain/HTN) treated with Thoracic Endovascular Aortic Repair (TEVAR).

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Peripheral Arterial Disease (PAD)

• Ankle-Brachial Index (ABI): Ratio of highest ankle systolic BP to highest brachial systolic BP.
  • Normal: 0.90–1.30.
  • Mild-Moderate PAD: 0.41–0.89.
  • Severe PAD / Critical Limb Ischemia: <=0.40.
  • Non-compressible calcified vessels (Diabetes/CKD): >1.40 (requires Toe-Brachial Index assessment).
• Medical Management: Supervised exercise therapy, Smoking cessation, High-intensity statin (Atorvastatin 80 mg), and Antiplatelet therapy (Clopidogrel 75 mg daily preferred over Aspirin per CAPRIE trial; or combination of Aspirin 100 mg daily + Rivaroxaban 2.5 mg bd per COMPASS trial).

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Pericardial & Myocardial Disease

1. Acute Pericarditis

• Diagnostic Criteria (Requires at least 2 of the following 4):
  1. Chest Pain: Sharp, pleuritic, relieved by sitting forward.
  2. Pericardial Friction Rub: High-pitched scratching triphasic sound.
  3. ECG Changes: Widespread concave ST-segment elevation with PR-segment depression (except leads aVR and V1).
  4. Pericardial Effusion: New or worsening on Echocardiogram.
• First-Line Treatment: High-dose NSAIDs (Ibuprofen 600–800 mg tds) or Aspirin (750–1000 mg tds) combined with Colchicine 0.5 mg daily (<70 kg) or 0.5 mg bd (>=70 kg) for 3 months. Colchicine reduces recurrence rates by 50% (ICAP trial). Systemic corticosteroids are second-line due to increased recurrence risk.

2. Cardiac Tamponade

• Accumulation of pericardial fluid under pressure compromising cardiac filling.
• Beck's Triad: Hypotension, Jugular Venous Distension (with absent y-descent), and Muffled Heart Sounds.
• Pulsus Paradoxus: Exaggerated fall in systolic BP >10 mmHg during inspiration.
• Echocardiography: Diastolic collapse of the right ventricle, early systolic collapse of the right atrium, and a dilated inferior vena cava without respiratory collapse.
• Emergency Treatment: Emergency bedside Pericardiocentesis or surgical pericardial window.

3. Constrictive Pericarditis

• Chronic fibrotic thickening and calcification of the pericardium limiting diastolic filling.
• Clinical Signs: Kussmaul's Sign (paradoxical rise in JVP on inspiration), Pericardial knock (early diastolic sound), ascites, and peripheral edema.
• Cardiac Catheterization: Equalization of end-diastolic pressures in all four cardiac chambers, with characteristic "dip-and-plateau" (square-root sign) in ventricular pressure tracings.
• Treatment: Surgical Pericardiectomy.