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Overview
Cardiac emergencies are among the most time-critical situations an EMT-Basic will encounter. This guide covers chest pain assessment, medication assistance, CPR/AED protocols, cardiogenic shock management, and foundational cardiac anatomy. Mastery of these concepts is essential for both the NREMT exam and real-world patient care.
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Section 1: Chest Pain Assessment
Key Concepts
Rapid, systematic assessment of chest pain is the foundation of cardiac emergency management. The goal is to identify potential cardiac causes quickly and guide treatment decisions.
OPQRST Mnemonic – Used to characterize chest pain:
• Onset – When did it start? Was it sudden or gradual?
• Provocation – What makes it better or worse?
• Quality – How does it feel? (pressure, squeezing, sharp?)
• Radiation – Does it spread to the arm, jaw, or shoulder?
• Severity – Rate pain on a 0–10 scale
• Time – How long has it been present?
SAMPLE History – Always obtain alongside OPQRST:
• Signs & Symptoms
• Allergies
• Medications (critical – cardiac patients may take nitroglycerin, blood thinners, beta-blockers)
• Pertinent past history
• Last oral intake
• Events leading up to this
Classic vs. Atypical Presentations
| Presentation Type | Description | Population |
|---|---|---|
| Classic | Pressure/squeezing center chest (angina pectoris) | General adult males |
| Atypical/Silent | Fatigue, nausea, shortness of breath | Diabetics, elderly, women |
Key Physiological Concepts
• Referred Pain – Cardiac pain radiates to the left arm, jaw, or shoulder due to shared nerve pathways between the heart and those areas. The brain misinterprets the origin of pain signals from the ischemic myocardium.
• Diaphoresis (sweating) – Indicates sympathetic nervous system activation; a classic sign of significant cardiovascular compromise and serious cardiac event (e.g., acute MI).
• Angina pectoris – Medical term for ischemic chest pain; results from inadequate oxygen delivery to the myocardium.
Key Terms
• Myocardium – Heart muscle tissue
• Ischemia – Insufficient oxygen delivery to tissue
• Diaphoresis – Profuse sweating; sign of sympathetic activation
• Angina pectoris – Chest pain from myocardial ischemia
• Referred pain – Pain felt at a location distant from its source
⚠️ Watch Out For
• Atypical MI presentations are heavily tested. Do not rule out cardiac emergencies in diabetics, elderly patients, or women just because they lack classic chest pain.
• Hypotension (systolic BP < 90 mmHg) + chest pain = cardiogenic shock or massive MI. This is a load-and-go situation — do not delay transport.
• Always ask about medications before treating — missing a patient's beta-blocker or blood thinner history can have serious consequences.
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Section 2: Nitroglycerin & Medications
Key Concepts
EMT-Basics may assist patients with their prescribed medications. Two primary medications in cardiac emergencies are nitroglycerin and aspirin.
Nitroglycerin
• Mechanism of Action: Vasodilator — relaxes vascular smooth muscle, reducing preload and myocardial oxygen demand; also dilates coronary arteries to improve blood flow
• Route: Sublingual (under the tongue) — allowed to dissolve
• Standard Dose: 0.4 mg (1/150 grain) per tablet
• Repeat Dosing: Up to 3 doses, every 3–5 minutes
• Reassessment Required: Blood pressure must be reassessed before each dose
Three Criteria Before Assisting with Nitroglycerin
1. ✅ Nitroglycerin is prescribed to this patient
2. ✅ Medical direction authorizes its use
3. ✅ Patient's systolic BP is above 100 mmHg
Nitroglycerin Contraindications
| Contraindication | Reason |
|---|---|
| Systolic BP < 100 mmHg | Can cause severe vasodilation and cardiovascular collapse |
| Phosphodiesterase inhibitors (e.g., sildenafil/Viagra) within 24–48 hours | Both cause vasodilation; combination produces severe, potentially fatal hypotension |
Aspirin
• Dose: 324 mg (four 81 mg baby aspirins)
• Route: Chewed, then swallowed
• Rationale: Chewing speeds absorption and maximizes antiplatelet effects to help prevent further clot formation
Key Terms
• Vasodilator – Agent that widens blood vessels
• Preload – Volume of blood returning to the heart; reduced by nitroglycerin
• Sublingual – Under the tongue
• Phosphodiesterase inhibitor – Drug class (e.g., Viagra) that amplifies vasodilatory effects
• Antiplatelet – Prevents platelets from clumping to form clots
⚠️ Watch Out For
• The BP cutoff for nitroglycerin is 100 mmHg (not 90 mmHg — that's the threshold for cardiogenic shock). Know both numbers.
• Always ask about Viagra/Cialis/Levitra (phosphodiesterase inhibitors) in your SAMPLE history. This is a classic NREMT trick question.
• You may assist with up to 3 doses — not 1, not unlimited. Count them and reassess BP each time.
• Aspirin must be chewed, not swallowed whole — this is frequently tested.
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Section 3: CPR & Resuscitation
Key Concepts
High-quality CPR is the most critical intervention in cardiac arrest. Consistent compression rate, depth, and minimal interruptions save lives.
Adult CPR – At a Glance
| Parameter | Standard |
|---|---|
| Compression-to-ventilation ratio | 30:2 (single or two-rescuer, without advanced airway) |
| Compression rate | 100–120 compressions/minute |
| Compression depth | At least 2 inches (5 cm), no more than 2.4 inches (6 cm) |
| Maximum CPR interruption | No more than 10 seconds |
| Hand position | Heel of hand on center of chest (lower half of sternum), hands interlaced, arms straight and perpendicular |
Two-Rescuer CPR with Advanced Airway
• Compression ratio: Continuous compressions at 100–120/min
• Ventilations: 1 breath every 6 seconds (10 breaths/min)
• No pausing for ventilations once advanced airway is placed
Why Technique Matters
• Full chest recoil – Allows the heart to refill with blood between compressions, maximizing stroke volume and coronary perfusion pressure. Leaning on the chest between compressions reduces effectiveness.
• Compression depth – Adequate depth (≥2 inches) is essential for generating sufficient blood flow to vital organs.
• Rate – Both too slow and too fast reduce CPR effectiveness.
Key Terms
• Coronary perfusion pressure – Pressure driving blood into the coronary arteries during CPR; maintained by full recoil and minimal pauses
• Stroke volume – Amount of blood pumped per heartbeat
• Advanced airway – Supraglottic airway or endotracheal tube; changes ventilation protocol
⚠️ Watch Out For
• The ratio is 30:2 regardless of single or two-rescuer adult CPR unless an advanced airway is in place.
• Do not exceed 10 seconds of interruption for any reason, including AED use.
• Incomplete recoil is a common error — do not lean on the patient's chest between compressions.
• Compression rate is 100–120/min — faster is not better.
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Section 4: AED Operation
Key Concepts
The AED analyzes cardiac rhythm and delivers shocks to treat shockable rhythms. EMTs must operate it quickly and safely.
Shockable Rhythms
| Rhythm | Description |
|---|---|
| Ventricular Fibrillation (VF) | Chaotic, disorganized electrical activity; ventricles quiver, no cardiac output |
| Pulseless Ventricular Tachycardia (pVT) | Rapid, organized rhythm with no effective pulse |
> Non-shockable rhythms (e.g., asystole, PEA) — AED will not advise a shock; continue CPR.
AED Pad Placement
Adult (Standard Placement):
• One pad: Upper right chest, below the clavicle
• One pad: Lower left lateral chest (apex position)
Pediatric Patients (under 8 years / under 55 lbs) — if only adult pads available:
• One pad: Center of the chest (anterior)
• One pad: Center of the back (posterior)
• Prevents pads from overlapping on a small chest
Special Situations
| Situation | Action |
|---|---|
| Permanent pacemaker or ICD | Place pads at least 1 inch away from the device |
| Wet surface or standing water | Move patient to dry area before AED use |
| Medication patch on skin | Remove patch and wipe skin before pad placement |
AED Sequence
1. Power on AED
2. Attach pads (correct placement)
3. Allow AED to analyze rhythm — stop CPR, do not touch patient
4. If shock advised: "CLEAR!" — visually confirm no contact
5. Deliver shock
6. Immediately resume CPR for 2 minutes — do not check pulse first
7. Allow AED to re-analyze after 2 minutes
Key Terms
• AED – Automated External Defibrillator
• Defibrillation – Delivery of electrical shock to terminate VF/pVT
• Ventricular fibrillation – Chaotic, non-perfusing cardiac rhythm; most common initial rhythm in sudden cardiac arrest
• Anterior-posterior placement – Pad positioning used for pediatric patients
⚠️ Watch Out For
• After a shock, immediately resume compressions — do not stop to check for a pulse. This is the most commonly missed step.
• AED pads on a pacemaker site must be moved at least 1 inch away — not avoided entirely.
• Never use an AED in or near water. Move the patient first.
• Only VF and pVT are shockable — know that asystole ("flatline") is NOT shockable.
• Pediatric anterior-posterior placement applies when pediatric pads are unavailable, not as a first choice.
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Section 5: Cardiogenic Shock & Complications
Key Concepts
Cardiogenic shock occurs when the heart fails as a pump, most commonly following a massive MI that damages a large portion of the left ventricle.
Signs & Symptoms of Cardiogenic Shock
• Hypotension (systolic BP < 90 mmHg)
• Tachycardia (compensatory)
• Pale, cool, clammy skin (peripheral vasoconstriction)
• Altered mental status (poor cerebral perfusion)
• Pulmonary edema (wet lungs, crackles)
EMT Treatment Priorities for Cardiogenic Shock
1. High-flow supplemental oxygen
2. Position of comfort — keep patient calm
3. Rapid transport — do not delay for on-scene interventions
4. Request ALS intercept
> This is a load-and-go situation. Time to definitive care is critical.
Pulmonary Edema
Cause: Left ventricular failure → blood backs up into pulmonary veins → increased hydrostatic pressure in pulmonary capillaries → fluid forced into alveoli → impaired gas exchange
Positioning: Sit the patient upright (high Fowler's position or legs dangling)
• Reduces venous return to the heart
• Decreases pulmonary congestion
• Makes breathing easier
Key Terms
• Cardiogenic shock – Circulatory failure from inadequate cardiac pump function
• Pulmonary edema – Fluid accumulation in the alveoli due to elevated pulmonary capillary pressure
• Hydrostatic pressure – Fluid pressure within blood vessels that drives fluid out when elevated
• Alveoli – Tiny air sacs in the lungs where gas exchange occurs
• High Fowler's position – Patient sitting upright at ~90°
⚠️ Watch Out For
• Cardiogenic shock is not treated by laying the patient flat — upright positioning is appropriate, especially with pulmonary edema.
• Do not give nitroglycerin in cardiogenic shock (systolic BP will be too low — below 100 mmHg).
• Transport should not be delayed for ALS procedures — request an intercept and move.
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Section 6: Cardiac Anatomy & Pathophysiology
Key Concepts
Understanding the underlying pathophysiology helps contextualize all assessment and treatment decisions.
Angina vs. AMI
| Feature | Angina Pectoris | Acute MI (AMI) |
|---|---|---|
| Cause | Reversible myocardial ischemia | Prolonged/complete coronary artery occlusion |
| Tissue damage | None — temporary | Yes — myocardial cell death (infarction) |
| Relief | Rest or nitroglycerin | Does NOT fully resolve with nitroglycerin |
| Urgency | Urgent | Immediate emergency |
Coronary Arteries & MI
• Function: Supply oxygenated blood directly to the myocardium
• Occlusion cause: Rupture of an atherosclerotic plaque triggers clot (thrombus) formation → blocks blood supply → ischemia → infarction of downstream heart muscle
• Time is muscle: Every minute of delay = more myocardial cell death
Ventricular Fibrillation (VF)
• Definition: Chaotic, disorganized electrical rhythm where ventricles quiver instead of contracting
• Consequence: Produces zero cardiac output → immediate cardiac arrest
• Without treatment: Brain death begins within 4–6 minutes
• Treatment: Defibrillation (AED) + CPR
Key Terms
• Atherosclerosis – Buildup of plaque inside arterial walls
• Thrombus – Blood clot
• Infarction – Death of tissue due to loss of blood supply
• Coronary arteries – Vessels supplying blood to the heart muscle itself
• Ventricular fibrillation – Chaotic non-perfusing rhythm; most treatable cause of sudden cardiac arrest
⚠️ Watch Out For
• Know the distinction: Angina resolves with nitroglycerin and rest; AMI does not (or only partially).
• VF produces no pulse and no cardiac output — it is not "any heartbeat." Do not confuse electrical activity with mechanical pumping.
• Atherosclerotic plaque rupture (not simply narrowing) is the most common trigger for acute MI.
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Quick Review Checklist ✅
Use this checklist before your exam to confirm mastery of the highest-yield concepts:
Assessment
• [ ] Can recite and apply OPQRST and SAMPLE correctly
• [ ] Know the three atypical MI populations (diabetics, elderly, women)
• [ ] Understand referred pain and why cardiac pain radiates
• [ ] Know that hypotension + chest pain = immediate transport
• [ ] Recognize diaphoresis as a sign of sympathetic activation and serious cardiac event
Medications
• [ ] Know nitroglycerin's **mechanism, dose (0.4 mg), route (sublingual),