2.2 Core Workflows and Decision Points

The STEMI Reperfusion Decision

Once a STEMI is identified, the single most important workflow is choosing a reperfusion strategy:

1. Primary PCI (preferred): if the patient can reach a catheterization lab with a door-to-balloon time of 90 minutes or less, PCI is the gold standard. The emergency nurse activates the cath-lab team, continues monitoring, and prepares the patient.
2. Fibrinolytics: if PCI cannot be performed within about 120 minutes of first medical contact, give a fibrinolytic (alteplase, tenecteplase, or reteplase) with a door-to-needle time of 30 minutes or less, provided there are no contraindications.

Absolute fibrinolytic contraindications the CEN expects you to recognize include any prior intracranial hemorrhage, ischemic stroke within 3 months, known intracranial neoplasm or arteriovenous malformation, active internal bleeding, suspected aortic dissection, and significant closed-head trauma within 3 months. After thrombolytics, monitor closely for bleeding and for reperfusion dysrhythmias (an accelerated idioventricular rhythm is common and usually benign).

Initial ACS Drug Therapy

Beyond reperfusion, the early pharmacologic bundle for ACS is high-yield. A useful memory frame is the modernized version of "MONA," given in priority order rather than alphabetical order:

The nitroglycerin trap: nitroglycerin is contraindicated in right ventricular infarction (often accompanying an inferior STEMI, leads II/III/aVF) because the right ventricle is preload-dependent and nitrates cause profound hypotension. It is also contraindicated within 24-48 hours of phosphodiesterase-5 inhibitors (sildenafil, tadalafil). When an inferior MI is suspected, obtain right-sided leads (V4R) before giving nitrates.

Acute Heart Failure and Pulmonary Edema

Acute decompensated heart failure with flash pulmonary edema presents with severe dyspnea, orthopnea, pink frothy sputum, crackles, an S3 gallop, and hypoxia. The classic workflow targets preload, afterload, and oxygenation:

• Position upright (high Fowler's, legs dependent) to reduce venous return.
• Oxygenation: apply supplemental oxygen, and use noninvasive positive-pressure ventilation (CPAP or BiPAP) to improve oxygenation and decrease work of breathing and preload.
• Loop diuretic: IV furosemide for fluid overload (onset within minutes IV).
• Vasodilator: IV or sublingual nitroglycerin to reduce preload and afterload when blood pressure tolerates it; nitroprusside for severe hypertensive pulmonary edema.
• Monitor B-type natriuretic peptide (BNP); a high BNP supports a cardiac cause of dyspnea.

The distinction the exam loves: in cardiogenic pulmonary edema the problem is pump failure and fluid backup, so you remove fluid and reduce afterload rather than give a bolus.

NSTEMI and Unstable Angina Workflow

Not every ACS goes to the cath lab in 90 minutes. NSTEMI and unstable angina are managed on a risk-stratified pathway rather than emergent reperfusion:

• Give the same antiplatelet and anticoagulant therapy (aspirin, a P2Y12 inhibitor, heparin).
• Add anti-ischemic therapy: nitroglycerin and a beta-blocker (if not contraindicated) to reduce myocardial oxygen demand.
• High-risk NSTEMI patients (ongoing pain, dynamic ECG changes, rising troponin, hemodynamic instability) proceed to early invasive angiography, typically within 24 hours.
• Lower-risk patients receive an ischemia-guided strategy with serial markers.

The key teaching point: a STEMI gets emergent reperfusion, while an NSTEMI gets urgent but not emergent catheterization. Fibrinolytics are used for STEMI only - they have no role in NSTEMI and can cause harm, which is a frequent distractor.

Beta-Blockers, Anticoagulation, and Monitoring

Early beta-blockade lowers heart rate, blood pressure, and contractility, reducing myocardial oxygen demand and infarct size. It is withheld in patients with signs of heart failure, cardiogenic shock, hypotension, bradycardia, or high-grade AV block - giving a beta-blocker to a patient sliding into cardiogenic shock can be fatal, a tested trap.

Throughout ACS care, watch for reperfusion dysrhythmias, recurrent chest pain (re-occlusion), and bleeding after antiplatelet, anticoagulant, or fibrinolytic therapy. Reassessment after each drug is the closed-loop habit the CEN rewards.

Right ventricular infarction management

When an inferior STEMI extends into the right ventricle, the management flips in an important way. Because the right ventricle is preload-dependent, these patients need volume, not preload reduction. The correct moves are to give IV fluids to support filling pressures and to withhold nitrates, diuretics, and morphine, all of which drop preload and can crash the blood pressure. If hypotension persists despite fluids, an inotrope such as dobutamine is added.

This is the mirror image of left-sided pump failure, where you remove fluid - and the CEN routinely places the two scenarios side by side to see whether you can tell a preload-dependent right-heart problem from fluid-overloaded left-heart failure.