9.2 Acute Coronary Syndrome, Heart Failure & Hypertensive Crises Nursing

9.2 Acute Coronary Syndrome, Heart Failure & Hypertensive Crises Nursing

Cardiovascular conditions such as Acute Coronary Syndrome (ACS), acute heart failure, and hypertensive crises account for significant medical admissions in Singapore hospitals. Registered nurses must master the pathophysiology, rapid diagnostic pathways, pharmacological management, and clinical safety protocols established by the Singapore Ministry of Health (MOH) and Health Sciences Authority (HSA).

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Acute Coronary Syndrome (ACS) Spectrum & Biomarkers

ACS represents a continuum of myocardial ischemia caused by atherosclerotic plaque erosion or rupture with secondary thrombus formation. ACS is divided into three clinical entities based on ECG findings and serum biomarkers:

Cardiac Biomarkers

• Cardiac Troponin T and I (cTnT / cTnI): The gold standard for detecting myocardial injury. Troponins rise within 2 to 4 hours post-infarction, peak at 12 to 24 hours, and remain elevated for 7 to 14 days. High-sensitivity troponin assays facilitate rapid triage in Singapore emergency departments.
• Creatine Kinase-MB (CK-MB): Rises in 3 to 6 hours, peaks at 12 to 24 hours, and normalizes within 48 to 72 hours. Useful for detecting early re-infarction if chest pain recurs post-PCI.

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Emergency ACS Nursing & Singapore MOH Clinical Pathways

Upon presentation of a patient with suspected ACS, a 12-lead ECG must be performed and interpreted within 10 minutes of hospital arrival.

Immediate Pharmacotherapy

1. Oxygen Therapy: Administered ONLY if SpO₂ < 90% or if the patient exhibits respiratory distress. MOH guidelines emphasize avoiding routine oxygen in normoxic patients, as hyperoxia causes coronary vasoconstriction.
2. Nitroglycerin (NTG): Sublingual 0.5 mg every 5 minutes up to 3 doses. Nursing Precautions: Check blood pressure prior to each dose. Absolute Contraindications: SBP <90 mmHg, severe bradycardia (<50 bpm) or tachycardia (>100 bpm), suspected Right Ventricular Infarction (V4R ST elevation), or recent use of phosphodiesterase-5 (PDE-5) inhibitors (Sildenafil within 24 hours, Tadalafil within 48 hours) due to severe refractory hypotension.
3. Aspirin: Administer 300 mg non-enteric coated chewable Aspirin stat for antiplatelet activity.
4. Dual Antiplatelet Therapy (DAPT): Loading dose of Ticagrelor 180 mg or Clopidogrel 300–600 mg per medical order.
5. Morphine IV: Reserved for severe, refractory chest pain. Administer in small IV titrations (2–4 mg) while monitoring respiratory status.

Reperfusion Targets & Post-PCI Nursing Care

• Primary PCI Door-to-Balloon (D2B) Target: In Singapore restructured hospitals (e.g., National University Heart Centre, Singapore General Hospital, National Heart Centre Singapore), the target D2B time is <90 minutes from hospital entry to balloon inflation for STEMI.
• Thrombolytic Therapy Target: If PCI is unavailable within 120 minutes, IV thrombolysis (e.g., Tenecteplase) is administered with a Door-to-Needle time <30 minutes.
• Post-PCI Care: Inspect puncture sites for bleeding or hematoma. Monitor distal neurovascular status hourly. For femoral access, maintain strict bed rest with the leg straight for 4 to 6 hours. Monitor for retroperitoneal hemorrhage (back/flank pain, unexplained hypotension, tachycardia).

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Heart Failure Nursing & Fluid Overload Management

Heart Failure (HF) is divided into HF with Reduced Ejection Fraction (HFrEF, EF ≤40%) and HF with Preserved Ejection Fraction (HFpEF, EF ≥50%).

Clinical Manifestations & Biomarkers

• Left-Sided Heart Failure: Exertional dyspnea, orthopnea, paroxysmal nocturnal dyspnea (PND), bilateral basilar crackles, S3 gallop, and pink frothy sputum in acute pulmonary edema.
• Right-Sided Heart Failure: Elevated JVP (>3 cm above sternal angle), bilateral dependent pitting edema, hepatomegaly, and ascites.
• BNP / NT-proBNP: Elevated levels (BNP >100 pg/mL, NT-proBNP >300 pg/mL) indicate ventricular wall stretch.

Nursing Interventions & Management

1. Positioning: High Fowler's position to reduce preload and optimize lung expansion.
2. Loop Diuretics (Furosemide): Administer IV Furosemide to promote diuresis. Monitor hourly urine output (>0.5–1 mL/kg/h), daily weights, and serum Potassium and Magnesium levels to prevent hypokalemia-induced arrhythmias.
3. Guideline-Directed Medical Therapy (GDMT) per MOH HF CPG: ARNI (Sacubitril/Valsartan) or ACEi/ARB, evidence-based Beta-blockers (Bisoprolol, Carvedilol), Mineralocorticoid Receptor Antagonists (Spironolactone), and SGLT2 inhibitors (Dapagliflozin/Empagliflozin).
4. Fluid & Sodium Restrictions: Enforce fluid restriction (1.2 to 1.5 L/day) and low-sodium diet (<2 g/day).
5. Patient Education: Instruct patients to weigh themselves daily every morning after voiding. Educate patients to report a weight gain of >1.5 to 2 kg over 2 days, which indicates worsening fluid overload.

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Hypertensive Crises: Urgency vs. Emergency

Hypertensive crisis is defined as severe blood pressure elevation with Systolic BP >180 mmHg or Diastolic BP >120 mmHg.

Target Organ Damage & BP Reduction Rules

• Target Organ Indicators: Encephalopathy, stroke, intracranial hemorrhage, acute aortic dissection, acute MI, acute pulmonary edema, acute kidney injury, or papilledema.
• Reduction Protocol: Lower Mean Arterial Pressure (MAP) by no more than 20% to 25% within the first hour, then gradually towards 160/100 mmHg over 2 to 6 hours. Excessively rapid drops cause ischemic cerebral, myocardial, or renal injury.
• Exception: In Acute Aortic Dissection, rapidly lower SBP to <120 mmHg within 20 minutes using IV Beta-blockers first to reduce shear stress.

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Medication Safety & HSA Standards

Vasoactive infusions (Nitroglycerin, Nitroprusside, Labetalol, Nicardipine) are High-Alert Medications under Health Sciences Authority (HSA) guidelines. Nurses must conduct independent double-checks of concentration and rate settings. Protect Sodium Nitroprusside infusions from light and monitor for thiocyanate toxicity (tinnitus, abdominal pain, metabolic acidosis) during prolonged infusions (>48h).