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ACLS – Acute Coronary Syndromes Algorithm Study Notes

Key Definitions & Pathophysiology

  • Myocardial Ischemia
    • Lack of O₂ supply to heart muscle → metabolic shift to anaerobic metabolism → accumulation of lactate, pain, and electrical instability.
    • Reversible if perfusion restored quickly.
  • Acute Angina
    • Clinical symptom: chest pain/pressure usually precipitated by exertion or stress.
    • Pathophysiologic correlate: transient ischemia without necrosis.
  • Acute Myocardial Infarction (MI)
    • Ongoing ischemia progresses to tissue injury and then permanent damage (necrosis).
    • Timely reperfusion limits infarct size → better LV function & survival.

Pre-Hospital (EMS) Assessment & Immediate Actions

  • Primary Survey
    • Assess Airway, Breathing, Circulation (ABCs).
  • Aspirin Administration
    • Rationale: immediate platelet inhibition → slows thrombus propagation.
    • Typical dose: 162–325 mg chewed unless contraindicated.
  • Adjunctive Medications to Consider
    • Oxygen if SpO_2 < 94\%, signs of hypoxemia, or respiratory distress.
    • Nitroglycerin (NTG) for pain/ischemia relief except in:
    • Right-sided MI
    • SBP < 90 mmHg
    • Phosphodiesterase-5 inhibitor within 24–48 h.
    • Morphine for persistent pain/anxiety or pulmonary edema refractory to NTG.
  • 12-Lead ECG Acquisition
    • Obtain and interpret within minutes of first medical contact (FMC).
    • Look specifically for ST-segment elevation criteria.

EMS Workflow for Identified ST Elevation (STEMI)

  • Early Notification
    • Transmit ECG or give verbal interpretation to receiving facility.
  • Time Documentation
    • Note exact symptom onset and FMC time; forms denominator for quality metrics.
  • Destination Decision
    • Transport directly to PCI-capable center or ED per regional STEMI protocol.
  • Hospital Responsibilities
    • Receiving center alerts STEMI team immediately on notification.
  • Fibrinolytic Checklist
    • EMS begins review to flag absolute / relative contraindications before arrival.

Hospital (ED / Cath Lab) Concurrent Assessment

  • STEMI Team Activation
    • Should already be in progress on EMS prenotification.
  • Re-check ABCs; secure airway if unstable.
  • IV Access
    • At least one large-bore line for meds & contrast.
  • Focused History & Physical
    • Time of onset, risk factors, prior CABG/PCI, bleeding history, medications.
  • Fibrinolytic Contraindication Review
    • Intracranial hemorrhage, ischemic stroke <3 mo, active bleeding, etc.
  • Diagnostics (draw STAT, do not delay reperfusion):
    • Cardiac markers (e.g., troponin).
    • CBC (anemia, platelet count).
    • Coagulation profile (PT/INR, aPTT) for anticoagulant management.
    • Portable chest X-ray (rule out dissection, pulmonary edema).

Time-Sensitive Quality Benchmarks (AHA Guidelines)

  • Door-to-Balloon (PCI) Goal
    • T_{D2B} \le 90\ \text{minutes} from hospital arrival to first balloon inflation.
  • Door-to-Needle (Fibrinolysis) Goal
    • T_{D2N} \le 30\ \text{minutes} if PCI unavailable within recommended time window.

Fibrinolytic Checklist – Absolute/Relative Contraindications (Highlights)

  • Prior intracranial hemorrhage or known cerebral vascular lesion.
  • Ischemic stroke within \le 3 months.
  • Active internal bleeding or suspected aortic dissection.
  • Severe uncontrolled hypertension (e.g., SBP > 180\,mmHg).

Pharmacologic Agents & Mechanisms (Contextual Significance)

  • Aspirin: Irreversibly inhibits COX-1 → \downarrow thromboxane A₂.
  • Nitroglycerin: \uparrow NO → coronary & venous vasodilation → \downarrow preload, pain.
  • Morphine: μ-receptor agonist → analgesia; also vasodilates; watch for hypotension.

Practical / Ethical Considerations

  • Rapid reperfusion saves myocardium—delays translate to larger infarct size and increased mortality.
  • Documentation of times ensures accountability and continuous system improvement.
  • Balancing speed vs. safety: fibrinolytics require rigorous contraindication screening; incorrect administration can be fatal.

Numeric & Formula Recap

  • SpO_2 \text{ target} \ge 94\%
  • T_{door\rightarrow balloon} \le 90\,min
  • T_{door\rightarrow needle} \le 30\,min

Source Reference

  • American Heart Association (2020). Advanced Cardiac Life Support Provider Manual.

Instructor of record: Assistant Professor Chantal Hensley – Course CVT 1205C.