EMS

Paramedic Cardiovascular Emergencies

This all-encompassing guide integrates information from all provided segments for a streamlined and comprehensive resource on managing cardiovascular emergencies as a paramedic.

Table of Contents

• I. Introduction & Scene Size-Up

• II. Patient Assessment

• III. Electrophysiology

• IV. Cardiac Dysrhythmias

• V. Atrioventricular (AV) Blocks

• VI. 12-Lead ECG Interpretation

• VII. Pathophysiology, Assessment, & Management of Specific Cardiovascular Conditions

• VIII. Special Considerations

• IX. Prep Kit

• X. Practice Scenarios

• XI. Resources

• XII. VITAL VOCABULARY

I. Introduction & Scene Size-Up

• Cardiovascular Disease (CVD): A broad term encompassing numerous heart and blood vessel disorders, including:

  • Hypertension

  • Coronary Heart Disease (CHD)

  • Peripheral Vascular Disease

  • Heart Failure

  • Cardiomyopathies

  • Congenital Heart Disease

• Coronary Heart Disease (CHD): CVD specific to coronary arteries, potentially causing:

  • Angina Pectoris

  • Acute Myocardial Infarction (AMI/Heart Attack)

• Acute Myocardial Infarction (AMI/Heart Attack): Myocardial tissue death due to blocked coronary artery blood flow.

• Cardiac Arrest: Cessation of the heart's mechanical pumping activity, resulting in the absence of circulation.

• Sudden Cardiac Arrest (SCA): Unexpected cardiac arrest necessitating resuscitation attempts.

• Sudden Cardiac Death (SCD): Unsuccessful resuscitation after SCA.

• Scene Size-Up:

  • Safety: Ensure personal, partner, patient, and bystander safety as the top priority.

  • Mechanism of Injury/Nature of Illness: Provides clues to potential cardiovascular compromise.

  • Number of Patients: Determines need for additional resources and assistance.

II. Patient Assessment

• Primary Survey: Rapidly assess and address life-threatening conditions:

  • Unresponsive Patients: CABDE (Circulation, Airway, Breathing, Disability, Exposure)

  • Responsive Patients: ABCDE (Airway, Breathing, Circulation, Disability, Exposure)

• History Taking:

  • Chief Complaint:

    • Chest pain/discomfort (Use OPQRST to characterize)

    • Dyspnea (Assess severity; consider pulmonary embolism, pneumothorax, heart failure)

    • Syncope (Differentiate cardiac vs. non-cardiac causes)

    • Palpitations (Onset, frequency, duration)

    • Fatigue (Onset, duration, associated symptoms)

  • OPQRST: Onset, Provocation/Palliation, Quality, Region/Radiation, Severity, Timing.

  • SAMPLE: Signs/Symptoms, Allergies, Medications, Past medical history, Last oral intake, Events leading up to the emergency.

  • Family History: Cardiac events, sudden death, history of heart disease.

• Secondary Assessment: More detailed evaluation to guide management decisions:

  • Physical Exam:

    • General Appearance: Mental status, level of distress, work of breathing.

    • Skin: Color (pallor, cyanosis, mottling), temperature, diaphoresis.

    • Neck: Jugular Venous Distention (JVD).

    • Chest: Inspection (symmetry, scars), palpation (tenderness, crepitus, Point of Maximal Impulse - PMI), auscultation (heart sounds, lung sounds).

    • Extremities: Edema, peripheral pulses (presence, strength, symmetry), capillary refill.

• Vital Signs:

  • Heart rate and rhythm (assess for irregularities, bradycardia, tachycardia)

  • Respiratory rate and quality (assess for labored breathing, use of accessory muscles)

  • Blood pressure (hypotension, hypertension, pulse pressure)

  • Pulse oximetry (SpO2)

  • End-Tidal CO2 (ETCO2) - provides information about ventilation and perfusion

• Cardiac Monitoring:

  • Continuous ECG monitoring (rhythm analysis and identification)

  • 12-lead ECG acquisition and interpretation (for diagnosis and localization)

• Reassessment: An ongoing process throughout patient care:

  • Repeat primary survey and vital signs frequently.

  • Evaluate the effectiveness of interventions.

  • Document all findings clearly and concisely.

III. Electrophysiology

• Depolarization: The process by which an electrical impulse triggers cardiac muscle contraction. Involves influx of sodium and calcium ions into the cell, making it more positively charged.

• Repolarization: The return of heart muscle cells to their resting electrical state following depolarization. Involves potassium exiting the cell and the restoration of ion balance through active transport.

• Cardiac Action Potential: The sequence of electrical changes that occurs within a heart muscle cell during one heartbeat. Divided into five phases (0-4), each associated with specific ion movements.

• Refractory Periods: Time periods during and after an action potential where the cell exhibits altered excitability:

  • Absolute Refractory Period (ARP): The cell is completely unresponsive to any stimulus, regardless of strength.

  • Relative Refractory Period (RRP): A stronger-than-normal stimulus is required to generate a new action potential.

• Cardiac Conduction System: Specialized cells responsible for initiating and conducting electrical impulses to ensure coordinated heart muscle contraction:

  • SA Node (Sinoatrial Node): The heart's dominant pacemaker, located in the right atrium, typically initiates impulses at 60-100 beats per minute.

  • Internodal Pathways: Conduct impulses from the SA node through the atria to the AV node.

  • AV Node (Atrioventricular Node): Located in the right atrium near the AV junction, it delays the impulse briefly, allowing the atria to contract fully and ventricles to fill.

  • Bundle of His: Specialized conductive fibers that transmit the impulse from the AV node to the bundle branches.

  • Bundle Branches: Divide into right and left branches, conducting impulses down the interventricular septum to their respective ventricles.

  • Purkinje Fibers: Network of fibers that spread throughout the ventricular myocardium, ensuring rapid and coordinated ventricular depolarization and contraction.

• Accessory Conduction Pathways: Abnormal electrical pathways between the atria and ventricles, bypassing the AV node, which can lead to rapid heart rhythms (tachycardias).

• Autonomic Nervous System (ANS) Influence: The ANS significantly influences heart rate and contractility:

  • Sympathetic Nervous System ("Fight-or-Flight"): Increases heart rate (chronotropy), force of contraction (inotropy), and vasoconstriction.

  • Parasympathetic Nervous System ("Rest-and-Digest"): Decreases heart rate (mainly via the vagus nerve), slows conduction through the AV node, and can cause mild vasodilation.

• Baroreceptors & Chemoreceptors: Specialized sensors that provide feedback to the ANS regarding blood pressure and chemistry:

  • Baroreceptors: Located in the aortic arch and carotid arteries, they detect changes in blood pressure and signal the ANS to adjust heart rate and vessel diameter.

  • Chemoreceptors: Sensitive to changes in blood oxygen, carbon dioxide, and pH levels, they trigger ANS responses to maintain homeostasis.

IV. Cardiac Dysrhythmias

• Definition: Disturbances in the normal heart rhythm, which can be benign or life-threatening.

• Causes: Numerous factors can disrupt the heart's electrical activity:

  • Electrolyte imbalances (potassium, magnesium, calcium)

  • Drug effects (medications, illicit substances)

  • Acid-base disturbances

  • Autonomic nervous system imbalance

  • Hypoxemia

  • Myocardial ischemia or infarction

  • Structural heart disease (valve disorders, cardiomyopathies)

• ECG Interpretation (Systematic Approach): Essential for identifying and managing dysrhythmias:

  • 1. Identify Waves:

    • P wave: Represents atrial depolarization (contraction).

    • QRS complex: Represents ventricular depolarization (contraction).

    • T wave: Represents ventricular repolarization (relaxation).

• 2. Measure PR Interval: Time from the beginning of the P wave to the beginning of the QRS complex; reflects conduction time through the atria and AV node (Normal: 0.12-0.20 seconds).

• 3. Measure QRS Duration: Time from the beginning to the end of the QRS complex; reflects ventricular depolarization time (Normal: ≤ 0.11 seconds).

• 4. Determine Rhythm Regularity: Assess if the heart rate is:

  • Regular: R-R intervals are consistently equal.

  • Regularly Irregular: R-R intervals vary in a predictable pattern.

  • Irregularly Irregular: R-R intervals vary without a pattern.

• 5. Calculate Heart Rate: Use one of the following methods:

  • 6-Second Method: Count the number of QRS complexes in a 6-second strip and multiply by 10.

  • Sequence Method: Select a QRS complex that falls on a heavy vertical line. Count down the heavy lines to the next QRS complex (300, 150, 100, 75, 60, 50).

  • 1500 Method: Most accurate, but time-consuming. Count the number of small boxes between two consecutive R waves and divide that number into 1500.

• Rhythm Categories:

  • Sinus Rhythms: Originate from the SA node.

    • Normal Sinus Rhythm: Rate: 60-100 bpm, regular rhythm, normal P wave preceding each QRS complex, normal PR interval and QRS duration.

    • Sinus Bradycardia: Rate: < 60 bpm, otherwise meets criteria for NSR.

    • Sinus Tachycardia: Rate: > 100 bpm, otherwise meets criteria for NSR.

    • Sinus Dysrhythmia: Rate varies slightly with respiration, common in children and young adults.

    • Sinus Arrest: SA node fails to fire, resulting in a pause with no P wave, QRS, or T wave.

    • Sick Sinus Syndrome (SSS): A group of rhythms caused by a malfunctioning SA node, resulting in alternating bradycardia and tachycardia.

• Atrial Rhythms: Originate from an ectopic focus within the atria.

  • Premature Atrial Complex (PAC): Early heartbeat originating in the atria. May appear as an early, abnormally shaped P wave, or the P wave may be hidden in the preceding T wave.

  • Supraventricular Tachycardia (SVT): Rapid heart rate (typically > 150 bpm) originating above the ventricles. Regular rhythm, P waves may be hidden in T waves or appear as "pseudo-S" waves.

  • Atrial Fibrillation (AF): Chaotic atrial activity, resulting in an irregularly irregular rhythm. No discernible P waves, often replaced by fibrillatory waves (f waves).

  • Atrial Flutter: Rapid, but regular, atrial activity, producing a "sawtooth" pattern of flutter waves (F waves). Ventricular rate is determined by the AV node's conduction ratio.

  • Wandering Atrial Pacemaker: Pacemaker site shifts between the SA node and other atrial foci, resulting in P wave variations.

  • Multifocal Atrial Tachycardia (MAT): Multiple atrial foci fire rapidly, causing tachycardia with irregular rhythm and varying P wave morphologies. Often seen in patients with COPD.

• AV Junctional Rhythms: Originate in the AV junction (AV node or Bundle of His).

  • Premature Junctional Complex (PJC): Early beat arising from the AV junction. P wave may be inverted, occur before, during, or after the QRS complex, or be absent.

  • Junctional Escape Rhythm: The AV junction assumes pacing responsibility when the SA node fails. Rate: 40-60 bpm, P waves may be inverted, absent, or occur after the QRS complex.

  • Accelerated Junctional Rhythm: Rate: 60-100 bpm, otherwise similar to junctional escape rhythm.

  • Junctional Tachycardia: Rate: > 100 bpm, otherwise similar to junctional escape rhythm.

• Ventricular Rhythms: Originate from an ectopic focus in the ventricles.

  • Premature Ventricular Complex (PVC): Early, wide, bizarre QRS complex with no preceding P wave. Often occur in patterns (bigeminy, trigeminy, couplets, triplets).

  • Idioventricular Rhythm (IVR): Slow ventricular rhythm that emerges when higher pacemakers fail. Rate: 20-40 bpm, no P waves, wide QRS complexes.

  • Accelerated Idioventricular Rhythm (AIVR): Rate: 40-100 bpm, otherwise similar to IVR.

  • Ventricular Tachycardia (VT): Rapid, life-threatening rhythm originating in the ventricles. Rate: > 100 bpm, wide QRS complexes, usually regular rhythm.

  • Ventricular Fibrillation (VF): Chaotic, disorganized electrical activity in the ventricles. No discernible P waves, QRS complexes, or T waves. Results in cardiac arrest.

• Pulseless Electrical Activity (PEA): Organized electrical activity on the ECG but without a palpable pulse. Represents a state of cardiac arrest where the electrical system is functioning, but the heart is unable to pump effectively.

• Management of Tachycardia With a Pulse: Treatment depends on patient stability, QRS complex width (narrow or wide), and rhythm regularity:

  • Stable Patients:

    • Vagal Maneuvers: Non-invasive techniques to stimulate the vagus nerve and slow heart rate (e.g., carotid sinus massage, Valsalva maneuver).

    • Adenosine: Ultra-short-acting medication that temporarily blocks AV node conduction, useful in diagnosing and treating SVT.

• Unstable Patients (hypotension, altered mental status, signs of shock, chest pain):

  • Synchronized Cardioversion: Delivery of a timed electrical shock synchronized with the R wave on the ECG. Used to convert SVT, atrial flutter, and stable VT with a pulse to a normal sinus rhythm.

• Management of Bradycardia:

  • Stable Patients: Monitor closely and observe for signs of deterioration.

  • Symptomatic Bradycardia (hypotension, altered mental status, chest pain, signs of shock):

    • Atropine: Anticholinergic medication that blocks parasympathetic stimulation of the heart, increasing heart rate.

    • Transcutaneous Pacing (TCP): Non-invasive method of pacing the heart using electrodes placed on the chest wall. Delivering electrical impulses to stimulate ventricular contraction.

    • Dopamine or Epinephrine Infusion: Used when atropine and TCP are ineffective or not indicated.

• Cardiac Arrest Management: Rapid and coordinated actions are crucial:

  • 1. High-Quality CPR: Effective chest compressions and ventilations are essential to circulate oxygenated blood and improve the chances of ROSC (return of spontaneous circulation).

    • Rate: 100-120 compressions per minute.

    • Depth: At least 2 inches (5 cm) for adults, 1/3 the depth of the chest for infants and children.

    • Allow for Full Chest Recoil: Ensure the chest fully re-expands after each compression.

    • Minimize Interruptions: Only stop compressions for essential interventions (rhythm checks, defibrillation, airway management).

    • Two-Rescuer CPR: Switch compressor roles every 2 minutes to prevent fatigue.

• 2. Defibrillation: Used to treat ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT), the two shockable rhythms.

  • Mechanism: Delivers a high-energy electrical shock to the heart to depolarize all cardiac cells simultaneously, allowing the SA node to regain control of the heart rhythm.

  • Early Defibrillation: Survival rates decrease significantly with each minute defibrillation is delayed.

  • AED vs. Manual Defibrillator:

    • AEDs (Automated External Defibrillators): Analyze the heart rhythm and guide the user through the defibrillation process. Ideal for use by lay rescuers and in out-of-hospital settings.

    • Manual Defibrillators: Require healthcare providers to interpret the ECG rhythm and determine if defibrillation is indicated. Allow for energy level adjustments and synchronized cardioversion.

• Safety: Ensure everyone is clear of the patient before delivering a shock.

• 3. Airway Management: Maintain a patent airway to facilitate effective ventilations:

  • Basic Airway Maneuvers: Head tilt-chin lift or jaw thrust (if cervical spine injury is suspected).

  • Airway Adjuncts: Oropharyngeal airway (OPA), nasopharyngeal airway (NPA).

  • Advanced Airway Management: Consider endotracheal intubation (ETI) if basic airway management is ineffective or the patient cannot protect their airway.

• 4. Medications: Administered intravenously (IV) or intraosseously (IO) during cardiac arrest:

  • Epinephrine:

    • Mechanism: Alpha-adrenergic effects (vasoconstriction) improve coronary and cerebral blood flow during CPR. Beta-adrenergic effects (increased heart rate and contractility) may help restart the heart.

    • Dosage: 1 mg IV/IO every 3-5 minutes.

• Amiodarone or Lidocaine: Antiarrhythmic medications used for refractory ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT) that does not respond to defibrillation and epinephrine.

  • Amiodarone: May be preferred as the first-line antiarrhythmic in cardiac arrest.

  • Lidocaine: May be used as an alternative to or in addition to amiodarone.

• 5. Post-Cardiac Arrest Care: Optimize care after ROSC to improve survival and neurological outcomes:

  • Optimize Ventilation and Oxygenation: Titrate oxygen to maintain SpO2 ≥ 94%.

  • 12-Lead ECG: Identify STEMI and other treatable conditions.

  • Treat Hypotension: IV/IO fluids, vasopressors if needed.

  • Targeted Temperature Management (TTM): Consider cooling the patient to 32-36°C (89.6-96.8°F) for 24 hours to improve neurological outcomes.

  • Rapid Transport: Transport to a facility capable of providing advanced cardiac care.

V. Atrioventricular (AV) Blocks

• Definition: Delays or interruptions in the conduction of electrical impulses from the atria to the ventricles. Usually occur at the level of the AV node, but can also occur in the His-Purkinje System.

• Types:

  • First-Degree AV Block: Prolonged PR interval (> 0.20 seconds) on the ECG, indicating a delay in conduction through the AV node. All impulses are still conducted to the ventricles. Usually asymptomatic, but may progress to higher-degree blocks.

  • Second-Degree AV Block: Some impulses from the atria are not conducted to the ventricles, resulting in "dropped" QRS complexes.

    • Type I (Mobitz I, Wenckebach): Progressively lengthening PR intervals until a QRS complex is dropped. Usually benign and well-tolerated.

    • Type II (Mobitz II): Intermittent dropped QRS complexes without progressive PR interval lengthening. More serious and likely to progress to complete heart block.

  • Third-Degree AV Block (Complete Heart Block): Complete dissociation of the atria and ventricles. The atria and ventricles beat independently, with the ventricles paced by a junctional or ventricular escape rhythm. Can be life-threatening if the ventricular escape rhythm is slow.

• Causes:

  • Myocardial Ischemia or Infarction: Especially inferior wall MI.

  • Increased Vagal Tone: Common in athletes and during sleep.

  • Medications: Beta-blockers, calcium channel blockers, digoxin.

  • Electrolyte Imbalances: Hyperkalemia.

• Management: Treatment depends on the severity of the block and the patient's symptoms:

  • Asymptomatic: Close monitoring and observation.

  • Symptomatic Bradycardia: (hypotension, altered mental status, chest pain, signs of shock)

    • Atropine: May be effective in increasing heart rate in some cases of first-degree and Type I second-degree blocks.

    • Transcutaneous Pacing (TCP): Non-invasive method of pacing the heart.

    • Dopamine or Epinephrine Infusion: Used when atropine and TCP are ineffective or not indicated.

    • Transvenous Pacing: Invasive procedure requiring specialized training and typically performed in a hospital setting.

• Definitive Treatment: Permanent pacemaker implantation is often necessary for higher-degree blocks that do not respond to medication or temporary pacing.

VI. 12-Lead ECG Interpretation

• Purpose: Records the heart's electrical activity from 12 different angles (leads), providing a more comprehensive picture of cardiac function than a rhythm strip. Used to diagnose:

  • Cardiac dysrhythmias

  • Myocardial ischemia, injury, and infarction (heart attack)

  • Chamber enlargement

  • Conduction abnormalities

  • Electrolyte disturbances

  • Drug toxicity

• Leads:

  • Limb Leads (Frontal Plane):

    • Standard Limb Leads: I, II, III

    • Augmented Limb Leads: aVR, aVL, aVF

• Precordial Leads (Horizontal Plane): V1, V2, V3, V4, V5, V6

• Systematic 12-Lead ECG Interpretation (7 Steps):

  • 1. Snapshot Review: Assess:

    • Lead placement and completeness

    • Artifact (interference)

    • Heart rate

    • QRS axis

• 2. Interpret the Rhythm: Use the 5-step approach outlined in the Cardiac Dysrhythmias section.

• 3. Determine Axis Deviation:

  • Normal Axis: -30° to +90°

  • Left Axis Deviation: -30° to -90°

  • Right Axis Deviation: +90° to +180°

• 4. Identify Conduction Disturbances: Look for:

  • AV blocks (first, second, third degree)

  • Bundle branch blocks (right, left)

  • Fascicular blocks (hemiblocks)

  • Pre-excitation syndromes (WPW)

• 5. Evaluate Chamber Size: Assess for:

  • Right atrial enlargement (P pulmonale)

  • Left atrial enlargement (P mitrale)

  • Right ventricular hypertrophy (tall R waves in V1, V2)

  • Left ventricular hypertrophy (deep S waves in V1, V2 and tall R waves in V5, V6)

• 6. Review for Ischemia, Injury, and Infarction: Analyze:

  • ST segment changes (elevation or depression)

  • T wave inversions

  • Pathological Q waves

• 7. Investigate Non-Cardiac Causes: ECG changes can also be caused by:

  • Pulmonary embolism

  • Electrolyte imbalances (hyperkalemia, hypokalemia, hypercalcemia, hypocalcemia)

  • Hypothermia

  • Pericarditis

  • Myocarditis

  • Drug toxicity (tricyclic antidepressants, digoxin)

• Key Concepts:

  • Contiguous Leads: Leads that "view" electrically similar areas of the heart. ST segment elevation or depression in contiguous leads helps localize the area of ischemia or injury.

  • Reciprocal Changes: ST segment and T wave changes that occur in opposite directions in leads that "face" each other. Reciprocal changes are a highly specific indicator of myocardial ischemia.

• Importance of Prompt 12-Lead ECG Transmission: For patients with suspected Acute Coronary Syndrome (ACS), especially STEMI, transmitting the 12-lead ECG to the receiving hospital while en route is crucial. This allows for early activation of the cardiac catheterization lab and significantly reduces time to reperfusion therapy.

VII. Pathophysiology, Assessment, & Management of Specific Cardiovascular Conditions

• Acute Coronary Syndromes (ACS): A group of conditions caused by a sudden reduction in blood flow to the heart muscle, usually due to a ruptured atherosclerotic plaque and thrombus formation.

  • Pathophysiology: Plaque rupture triggers platelet aggregation and thrombus formation, obstructing blood flow in a coronary artery. The degree of obstruction determines the severity of ischemia and the type of ACS.

  • Types:

    • Unstable Angina: Chest pain that is new, worsening, or occurs at rest. Represents a change in the typical angina pattern. No evidence of myocardial cell death.

    • Non-ST Segment Elevation Myocardial Infarction (NSTEMI): Myocardial infarction with ST depression or T wave inversion on the ECG, but no ST elevation. Indicates myocardial injury with cell death.

    • ST Segment Elevation Myocardial Infarction (STEMI): Myocardial infarction characterized by ST elevation in two or more contiguous leads on the ECG. Indicates significant myocardial injury with cell death.

• Risk Factors: Factors that increase the likelihood of developing ACS:

  • Modifiable: Smoking, hypertension, dyslipidemia (high cholesterol), diabetes, obesity, physical inactivity, unhealthy diet, excessive alcohol consumption.

  • Non-Modifiable: Age, male sex, family history of premature coronary artery disease, genetics.

  • Other/Contributing: Stress, low socioeconomic status.

• Assessment:

  • History: Characterize chest pain using OPQRST, assess for associated symptoms (nausea, vomiting, diaphoresis, dyspnea), medical history, medications, allergies.

  • Physical Exam: Vital signs (heart rate, blood pressure, respiratory rate, SpO2), assess for signs of distress, diaphoresis, skin color, lung sounds (rales may indicate heart failure), heart sounds (murmurs, S3, S4).

  • 12-Lead ECG: Essential for differentiating between unstable angina, NSTEMI, and STEMI.

• Management:

  • 1. Oxygen: Administer supplemental oxygen if SpO2 is < 94%.

  • 2. Aspirin: Administer 160-325 mg of chewable aspirin (unless contraindicated by allergy or active GI bleeding). Aspirin inhibits platelet aggregation and reduces thrombus formation.

  • 3. Nitroglycerin: Administer sublingual nitroglycerin (0.4 mg tablet or spray) every 5 minutes for up to three doses if the patient is experiencing chest pain, is not hypotensive (SBP < 90 mmHg), and is not taking phosphodiesterase inhibitors (e.g., Viagra, Cialis). Nitroglycerin is a vasodilator that can relieve chest pain by dilating coronary arteries and improving blood flow to the heart muscle. It can also reduce preload and afterload, decreasing the heart's workload.

  • 4. Morphine Sulfate: Consider morphine sulfate for pain relief if nitroglycerin is ineffective or contraindicated. Monitor for respiratory depression and hypotension.

  • 5. Reperfusion Therapy: Definitive treatment for STEMI, aimed at restoring blood flow to the blocked coronary artery as quickly as possible.

    • Percutaneous Coronary Intervention (PCI): Preferred reperfusion strategy. Performed in a cardiac catheterization lab, involving balloon angioplasty and/or stent placement to open the blocked artery.

    • Fibrinolytic Therapy ("Clot-Busting" Medications): Administered intravenously to dissolve blood clots. Used when PCI is not readily available. Careful patient selection is crucial due to the risk of bleeding complications.

• 6. Additional Medications: Other medications that may be used in the management of ACS include:

  • Antiplatelet Agents: (e.g., clopidogrel, ticagrelor) - prevent platelet aggregation and further clot formation.

  • Beta-Blockers: (e.g., metoprolol, atenolol) - reduce heart rate and blood pressure, decreasing myocardial oxygen demand.

  • ACE Inhibitors: (e.g., lisinopril, enalapril) - long-term management to improve cardiac function and reduce the risk of future cardiac events.

• 7. Rapid Transport: Transport to a facility capable of providing definitive care for ACS, including PCI and fibrinolytic therapy.

• Heart Failure: A complex clinical syndrome that results from any structural or functional impairment of ventricular filling or ejection of blood.

  • Types:

    • Left-Sided Heart Failure: Most common type. The left ventricle cannot pump effectively, causing blood to back up into the lungs (pulmonary edema).

      • Systolic Heart Failure: The left ventricle cannot contract forcefully enough to eject blood effectively (reduced ejection fraction).

      • Diastolic Heart Failure: The left ventricle cannot relax and fill properly (preserved ejection fraction).

• Right-Sided Heart Failure: Often a consequence of left-sided heart failure. The right ventricle cannot pump effectively, causing fluid to back up into the veins and body tissues (peripheral edema).

• Causes:

  • Coronary Artery Disease (CAD): Most common cause.

  • Hypertension: Increases afterload, making the heart work harder.

  • Valvular Heart Disease: Stenotic or regurgitant valves disrupt blood flow.

  • Myocarditis: Inflammation of the heart muscle.

  • Cardiomyopathy: Disease of the heart muscle itself.

• Assessment:

  • History: Assess for dyspnea (especially on exertion or when lying flat - orthopnea), paroxysmal nocturnal dyspnea (PND), fatigue, weakness, edema (legs, ankles, abdomen), weight gain, decreased urine output, chest pain, palpitations.

  • Physical Exam: Vital signs (tachycardia, tachypnea, hypotension), lung sounds (rales/crackles - fluid in lungs), heart sounds (S3 gallop - indicative of fluid overload), jugular venous distention (JVD), peripheral edema, hepatomegaly (enlarged liver).

• Management:

  • 1. Oxygen: Administer supplemental oxygen if SpO2 < 94%.

  • 2. Positioning: Sit the patient upright with legs dangling to reduce venous return and ease breathing.

  • 3. Nitroglycerin: May be administered sublingually if the patient is not hypotensive, as it can reduce preload and afterload, improving cardiac output.

  • 4. CPAP: Consider CPAP (Continuous Positive Airway Pressure) for patients with severe respiratory distress and pulmonary edema. CPAP helps improve oxygenation and reduces pulmonary edema by increasing pressure in the airways, forcing fluid back into the circulation.

  • 5. Fluid Management: Use caution with IV fluids, as patients with heart failure are often fluid overloaded. Monitor closely for signs of worsening pulmonary edema.

  • 6. Rapid Transport: Transport to a facility capable of providing advanced cardiac care.

• Cardiac Tamponade: A life-threatening condition in which fluid accumulates in the pericardial sac (the sac surrounding the heart), compressing the heart and impairing its ability to fill with blood.

  • Causes:

    • Penetrating Trauma: Stab wounds, gunshot wounds.

    • Blunt Trauma: Motor vehicle accidents, falls.

    • Pericarditis: Inflammation of the pericardium.

    • Malignancy: Cancerous tumors in the chest.

    • Iatrogenic: Complications from medical procedures (e.g., central line placement).

• Assessment:

  • Beck's Triad: Classic, but not always present, triad of symptoms:

    • Muffled Heart Sounds: Due to fluid surrounding the heart.

    • Jugular Venous Distention (JVD): Impaired venous return to the heart.

    • Hypotension: Decreased cardiac output.

• Pulsus Paradoxus: A decrease in systolic blood pressure of > 10 mmHg during inspiration.

• ECG: May show low voltage QRS complexes and electrical alternans (alternating heights of QRS complexes).

• Management:

  • 1. Oxygen: Administer supplemental oxygen.

  • 2. IV Fluids: May be used cautiously to increase preload, but be aware of the risk of worsening tamponade.

  • 3. Rapid Transport: Immediate transport to a facility capable of performing pericardiocentesis is essential.

  • 4. Pericardiocentesis: Definitive treatment involving the insertion of a needle into the pericardial sac to drain the accumulated fluid and relieve pressure on the heart.

• Cardiogenic Shock: A state of critical end-organ hypoperfusion due to the heart's inability to pump effectively. Often a complication of a large myocardial infarction.

  • Causes: Conditions that severely impair the heart's pumping ability:

    • Myocardial Infarction (MI): Most common cause.

    • Myocarditis: Inflammation of the heart muscle.

    • Cardiomyopathy: Disease of the heart muscle.

    • Valvular Heart Disease: Severe valve dysfunction.

    • Cardiac Tamponade: Fluid compression of the heart.

• Assessment:

  • Hypotension: Systolic blood pressure < 90 mmHg or a decrease of > 30 mmHg from baseline.

  • Signs of Hypoperfusion: Altered mental status, cool and clammy skin, weak peripheral pulses, oliguria (decreased urine output).

  • Pulmonary Edema: Rales/crackles on lung auscultation, dyspnea.

  • ECG: May show ST-segment elevation or depression, Q waves, or other signs of ischemia or infarction.

• Management: Aggressive treatment is required to improve cardiac output and restore tissue perfusion:

  • 1. Oxygen: Administer supplemental oxygen.

  • 2. IV Access: Establish two large-bore IV lines.

  • 3. Fluid Challenge: Administer IV fluids cautiously, as patients with cardiogenic shock may be fluid overloaded. Monitor for signs of worsening pulmonary edema.

  • 4. Vasopressors: Medications used to increase blood pressure and improve cardiac output.

    • Dopamine: Increases heart rate and contractility at lower doses. Vasoconstriction at higher doses.

    • Norepinephrine: Potent vasoconstrictor that increases blood pressure.

• 5. Inotropic Agents: Medications that improve the heart's contractility.

  • Dobutamine: Increases heart muscle contractility, improving cardiac output.

• 6. Mechanical Circulatory Support: In severe cases, devices like an intra-aortic balloon pump (IABP) or a left ventricular assist device (LVAD) may be used to support the heart's pumping ability.

• 7. Rapid Transport: Transport to a facility capable of providing advanced cardiac care, including a cardiac catheterization lab and cardiothoracic surgery.

• Hypertensive Emergencies: Severe elevations in blood pressure (typically > 180/120 mmHg) that result in target organ damage.

  • Causes:

    • Untreated or Uncontrolled Hypertension: Most common cause.

    • Kidney Disease: Disruption of the renin-angiotensin-aldosterone system.

    • Drug Use: Cocaine, amphetamines.

    • Preeclampsia: Pregnancy-induced hypertension.

    • Head Injury: Increased intracranial pressure.

• Assessment:

  • Elevated Blood Pressure: Typically >180/120 mmHg.

  • Signs of Target Organ Damage:
    * Neurological: Headache, altered mental status, seizures, stroke symptoms.
    * Cardiac: Chest pain, shortness of breath, acute pulmonary edema, aortic dissection.
    * Renal: Decreased urine output, acute kidney injury.
    * Management:
    * 1. Oxygen: Administer supplemental oxygen if SpO2 is < 94%.
    * 2. IV Access: Establish IV access.
    * 3. Blood Pressure Control: Medications to lower blood pressure gradually and carefully. Rapid blood pressure reduction can lead to ischemia and organ damage.
    * Labetalol: Beta-blocker and alpha-blocker, reduces heart rate and vasodilates.
    * Nicardipine: Calcium channel blocker, vasodilates.
    * 4. Treat Underlying Cause: If possible (e.g., insulin for hyperglycemic hyperosmolar state).
    * 5. Transport: To a facility capable of monitoring and managing complications.

• Infectious Diseases of the Heart: Inflammation of the heart structures caused by infectious agents (bacteria, viruses, fungi, parasites).

  • Types:

    • Endocarditis: Infection of the inner lining of the heart, including the heart valves. Most commonly caused by bacteria, often entering the bloodstream during dental procedures, IV drug use, or other invasive procedures. Can lead to heart valve damage, heart failure, and stroke.

      • Assessment: Fever, chills, fatigue, night sweats, weight loss, heart murmur, signs of heart failure, embolic events (stroke, pulmonary embolism).

      • Management: Supportive care, IV fluids, antibiotics (often long-term).

• Pericarditis: Inflammation of the pericardium. Can be caused by viral infections, bacterial infections, autoimmune disorders, or chest trauma. Can lead to pericardial effusion and cardiac tamponade.

  • Assessment: Sharp, pleuritic chest pain that worsens with inspiration and lying down, relieved by sitting up and leaning forward. Pericardial friction rub on auscultation.

  • Management: Supportive care, pain management (NSAIDs), colchicine (anti-inflammatory), treatment of underlying cause.

• Myocarditis: Inflammation of the heart muscle (myocardium). Most commonly caused by viral infections, but can also be caused by bacterial infections, parasites, autoimmune disorders, and certain medications. Can lead to heart failure, arrhythmias, and sudden cardiac death.

  • Assessment: Chest pain, fatigue, shortness of breath, palpitations, signs of heart failure.

  • Management: Supportive care, treatment of heart failure (if present), antiviral medications (if viral cause).

• Aortic Aneurysm: A weakening and bulging of the wall of the aorta, the main artery that carries blood from the heart to the body. Can occur anywhere along the aorta, but most common in the abdominal aorta (abdominal aortic aneurysm - AAA). Rupture of an aortic aneurysm is a surgical emergency and often fatal.

  • Types:

    • Thoracic Aortic Aneurysm: Located in the chest cavity.

    • Abdominal Aortic Aneurysm (AAA): Located in the abdomen.

• Assessment:

  • Symptoms: Many aneurysms are asymptomatic and detected incidentally. When symptoms occur, they depend on the location and size of the aneurysm. May include:

    • Thoracic: Chest pain, back pain, hoarseness, difficulty swallowing, cough.

    • Abdominal: Pulsating sensation in the abdomen, abdominal pain, back pain.

• Physical Exam: A pulsatile mass may be palpable in the abdomen for AAAs. Listen for bruits (abnormal sounds) over the aneurysm.

• Imaging: Ultrasound, CT scan, MRI are used to diagnose and monitor aneurysms.

• Management:

  • Unruptured: Management depends on size, growth rate, symptoms, and overall health. May include:

    • Watchful Waiting: Monitoring with regular imaging studies.

    • Lifestyle Modifications: Blood pressure control, smoking cessation.

    • Surgical Repair: Recommended for large aneurysms or those that are rapidly growing.

• Ruptured: A surgical emergency requiring immediate intervention:

  • Signs and Symptoms: Sudden, severe pain in the back, abdomen, or chest; hypotension; signs of shock.

  • Management:

    • Oxygen: High-flow oxygen.

    • IV Access: Establish two large-bore IV lines.

    • Fluid Resuscitation: IV fluids to maintain blood pressure.

    • Pain Management: Morphine.

    • Rapid Transport: Immediate transport to a facility capable of emergency surgery.

• Acute Arterial Occlusion: A sudden blockage of an artery, typically due to a blood clot (thrombus) or a piece of a blood clot that has broken off and traveled through the bloodstream (embolus). Most common in the legs (acute limb ischemia).

  • Assessment:

    • 6 Ps of Acute Limb Ischemia:

      • Pain: Sudden, severe pain in the affected limb.

      • Pallor: Pale or mottled skin.

      • Pulselessness: Absent or diminished pulses distal to the occlusion.

      • Paresthesia: Numbness or tingling.

      • Paralysis: Weakness or inability to move the affected limb.

      • Poikilothermia: Coolness of the affected limb.

• Management:

  • Oxygen: Administer supplemental oxygen.

  • Limb Positioning: Keep the affected limb level or slightly dependent (do not elevate).

  • Pain Management: Morphine.

  • Rapid Transport: Immediate transport to a facility capable of surgical or catheter-based intervention to restore blood flow.

• Acute Deep Vein Thrombosis (DVT): A blood clot that forms in a deep vein, most commonly in the legs. Can cause swelling, pain, and tenderness in the affected area. The primary concern is the potential for the clot to break free and travel to the lungs (pulmonary embolism - PE).

  • Risk Factors:

    • Prolonged Immobility: Long flights, bed rest.

    • Recent Surgery: Especially orthopedic surgery.

    • Pregnancy: Hormonal changes and increased pressure on veins.

    • Cancer: Certain types of cancer and cancer treatments.

    • Inherited Clotting Disorders: Factor V Leiden, prothrombin gene mutation.

    • Other: Obesity, smoking, older age, family history.

• Assessment:

  • History: Risk factors, unilateral leg swelling, pain, tenderness, warmth, redness.

  • Physical Exam: Assess for asymmetry in leg circumference, edema, tenderness, warmth, redness. Homan's sign (pain on dorsiflexion of the foot) is not reliable and should not be used to rule in or out DVT.

  • Imaging: Ultrasound is the diagnostic test of choice.

• Management:

  • Anticoagulation Therapy: The primary treatment for DVT. Medications (blood thinners) prevent clot growth and reduce the risk of PE.

    • Heparin: Administered intravenously or subcutaneously.

    • Warfarin (Coumadin): Oral medication, requires monitoring to ensure therapeutic levels.

    • Newer Oral Anticoagulants: (e.g., rivaroxaban (Xarelto), apixaban (Eliquis), edoxaban (Savaysa)) - convenient, fixed doses, do not require routine blood monitoring.

• Supportive Care: Elevation of the affected limb, compression stockings.

VIII. Special Considerations

• Wearable Cardioverter-Defibrillators (WCDs): External devices worn by patients at high risk for sudden cardiac arrest (SCA).

  • Recognition: Look for the vest under the patient's clothing.

  • Management: If the WCD delivers a shock, assess the patient and provide appropriate care. If the patient is in cardiac arrest, follow standard ACLS protocols.

• Artificial Pacemaker Rhythms: Pacemakers are implanted devices that regulate the heart rate.

  • ECG Recognition: Paced rhythms appear as spikes on the ECG, followed by a P wave (atrial pacing) or a QRS complex (ventricular pacing).

  • Pacemaker Malfunctions: Can cause bradycardia, tachycardia, or failure to pace.

• Prehospital Fibrinolytic Checklist: Used to determine patient eligibility for fibrinolytic therapy (clot-busting medication). Consider:

  • Time of symptom onset

  • Contraindications (e.g., active bleeding, recent surgery, stroke)

• Systems of Care for STEMI: Timely reperfusion is crucial for optimal STEMI outcomes. EMS plays a vital role in:

  • Early recognition and 12-lead ECG acquisition.

  • Rapid transport to a PCI-capable facility.

  • Pre-arrival notification to the receiving hospital.

• Cardiovascular Conditions in Special Populations:

  • Patients with Ventricular Assist Devices (VADs): Mechanical pumps implanted to assist a failing heart.

    • Assessment: Assess VAD function (humming sound, alarms).

    • Management: Supportive care, transport to a VAD-capable facility.

• Pregnant Patients: Physiological changes of pregnancy impact cardiac assessment and management.

  • Supine Hypotensive Syndrome: Avoid supine positioning in later pregnancy due to compression of the vena cava. Use left lateral tilt.

  • CPR Modifications: Manual uterine displacement to the left.

  • Medications: Consult with medical control regarding fetal risks.

• Pediatric Patients: Consider developmental and physiological differences in children.

  • Drug Dosages: Weight-based calculations are essential.

  • CPR Techniques: Age-appropriate techniques.

  • ECG Interpretation: Normal values vary with age.

• Mechanical CPR Devices: Automated devices that deliver chest compressions, potentially improving CPR quality and consistency.

  • Types:

    • Load-Distributing Band (LDB): Compresses the chest using a band that wraps around the patient's chest.

    • Piston Device: Compresses the chest using a piston that depresses the sternum.

• Advantages: May improve CPR quality and consistency, reduce rescuer fatigue, allow for safe transport of patients receiving compressions.

• Disadvantages: Can interfere with other interventions, may cause chest injuries, requires specific training.

• Extracorporeal CPR (eCPR): A highly invasive technique that involves circulating a patient's blood outside of the body to provide oxygenation and circulation during cardiac arrest.

  • Indications: Refractory cardiac arrest, select cases of potentially reversible cardiac arrest.

  • Limitations: Requires specialized equipment and trained personnel, resource-intensive, not available at all hospitals.

  • Transport Considerations: Transport to a facility with eCPR capabilities.

• Termination of Resuscitation: The decision to cease resuscitation efforts should be made collaboratively by the EMS team and medical control, considering factors such as:

  • Downtime: The length of time the patient has been in cardiac arrest.

  • Witnessed vs. Unwitnessed Arrest: Witnessed arrests have better outcomes.

  • Initial Rhythm: Shockable rhythms (VF, pVT) have better outcomes than asystole or PEA.

  • Return of Spontaneous Circulation (ROSC): Whether ROSC has been achieved and sustained.

  • Patient's Wishes: Advance directives (DNR orders).

IX. Cardiovascular Emergencies: A Concise Review for Paramedics:

The cardiovascular system, comprising the heart and blood vessels, delivers oxygen and nutrients to the body's cells while removing metabolic waste products. It also plays a vital role in transporting hormones. Understanding this system is critical for paramedics, as recognizing and managing cardiovascular emergencies is essential in prehospital care.

Cardiovascular Diseases (CVDs) and Acute Coronary Syndromes (ACSs):

CVDs encompass various disorders affecting the heart and blood vessels, including hypertension, peripheral vascular disease, heart failure, cardiomyopathies, and congenital heart disease. Coronary Heart Disease (CHD), a type of CVD, specifically impacts the coronary arteries, potentially leading to angina pectoris and acute myocardial infarction (AMI), commonly known as a heart attack.

ACSs are a series of conditions caused by a sudden reduction of coronary artery blood flow. The three major ACSs are:

• Unstable Angina: Chest pain that differs from the patient's typical angina pattern, often occurring at rest.

• Non-ST Segment Elevation Myocardial Infarction (NSTEMI): Myocardial infarction without ST elevation on the ECG, but with other ECG changes and elevated cardiac markers.

• ST Segment Elevation Myocardial Infarction (STEMI): Myocardial infarction characterized by ST elevation on the ECG, indicating significant myocardial injury.

Patients experiencing an ACS often present with chest discomfort, shortness of breath (dyspnea), fainting (syncope), palpitations, and fatigue.

Cardiac Arrest:

Cardiac arrest occurs when the heart stops pumping effectively, leading to the cessation of blood circulation. Sudden Cardiac Arrest (SCA) is an unexpected event requiring immediate resuscitation. Sudden Cardiac Death (SCD) occurs when resuscitation attempts are unsuccessful.

Electrical Activity of the Heart:

The heart's mechanical pumping action relies on electrical impulses. Depolarization, triggered by electrical impulses, initiates heart muscle contraction. The heart's electrical conduction system ensures orderly and coordinated contractions. This system includes the sinoatrial (SA) node, the heart's primary pacemaker, the atrioventricular (AV) node, the bundle of His, and the Purkinje fibers. Any disruption in this system can lead to cardiac dysrhythmias, potentially requiring interventions like atropine, transcutaneous pacing (TCP), or dopamine/epinephrine infusion.

Electrocardiogram (ECG):

An ECG records the heart's electrical activity. A 12-lead ECG provides a comprehensive view from 12 different angles, allowing for detailed analysis of heart rhythm, conduction, chamber size, and evidence of ischemia or infarction. Paramedics must be proficient in ECG interpretation, as it's crucial for diagnosing various cardiac conditions, including ACSs, dysrhythmias, and conduction abnormalities.

Managing Cardiovascular Emergencies:

Rapid assessment, early recognition of critical conditions, and prompt intervention are essential in managing cardiovascular emergencies. High-quality CPR, defibrillation for shockable rhythms (VF and pulseless VT), airway management, medication administration (e.g., oxygen, aspirin, nitroglycerin, morphine), and rapid transport to a facility capable of providing definitive care are key components of prehospital management. Post-cardiac arrest care focuses on optimizing cardiopulmonary function and vital organ perfusion.

Key Points to Remember:

• Time is muscle in ACS: rapid reperfusion is crucial for minimizing heart damage.

• Patients may present with atypical symptoms, especially older adults, women, and diabetics. Be alert for anginal equivalents.

• Prompt 12-lead ECG acquisition and transmission to the receiving facility are essential for timely STEMI management.

• A systematic approach to assessment, rhythm interpretation, and treatment is vital for optimal patient outcomes.

Further Exploration:

This review provides a fundamental overview of cardiovascular emergencies for paramedics. Deeper exploration of specific conditions, interventions, and management strategies is crucial. Consult textbooks, online resources, and attend training courses to expand your knowledge and enhance your expertise in cardiovascular care.

X. Practice Scenarios

• Scenario 1:

  • Dispatch: 58-year-old male with chest pain, diaphoretic.

  • On Arrival: Patient is alert and oriented but appears anxious, clutching his chest. He describes a crushing sensation that started 20 minutes ago while mowing the lawn. He denies any radiation of the pain. He has a history of hypertension and hyperlipidemia but does not take his medications regularly.

  • Vitals: BP: 150/98, HR: 110, RR: 22, SpO2: 92%.

  • 12-Lead ECG: ST segment elevation in leads II, III, aVF.

  • How would you manage this patient?

• Scenario 2:

  • Dispatch: 70-year-old female found unresponsive.

  • On Arrival: The patient is unresponsive, apneic, and pulseless. Family states she has a history of heart failure.

  • Initial Rhythm: Ventricular fibrillation (VF).

  • How would you manage this patient?

• Scenario 3:

  • Dispatch: 50-year-old male with palpitations, feeling dizzy.

  • On Arrival: Patient is alert and oriented, complains of a rapid heartbeat and lightheadedness.

  • Vitals: BP: 110/70, HR: 180, regular rhythm, RR: 20, SpO2: 98%.

  • 12-Lead ECG: Supraventricular tachycardia (SVT).

  • How would you manage this patient?

• Scenario 4:

  • Dispatch: 62-year-old female with shortness of breath, history of hypertension and diabetes.

  • On Arrival: Patient is sitting upright, struggling to breathe, audible wheezes. She states she woke up feeling short of breath and it has been worsening.

  • Vitals: BP: 180/110, HR: 122, RR: 28 and labored, SpO2: 88%.

  • Lung Sounds: Diffuse crackles (rales) bilaterally.

  • How would you manage this patient?

XI. Resources

• American Heart Association (AHA): https://www.heart.org/

• National Association of Emergency Medical Technicians (NAEMT): https://www.naemt.org/

• National Registry of Emergency Medical Technicians (NREMT): https://www.nremt.org/

• Your paramedic textbooks and associated online resources.

• Cardiac rhythm interpretation apps and websites (e.g., ECG Rhythm & Strip, Skillstat ECG Simulator, Life in the Fast Lane ECG Library)

XII. VITAL VOCABULARY

aberration A term describing the shape of the QRS complex in aberrantly (abnormally) conducted beats.

absolute refractory period (ARP) The early phase of cardiac repolarization, during which the heart muscle cannot be stimulated to depolarize; also known as the effective refractory period.

acute coronary syndromes (ACSs) A series of cardiac conditions caused by an abrupt reduction in coronary artery blood flow.

acute myocardial infarction (AMI) Cardiac ischemia that occurs when sudden narrowing or complete occlusion of a coronary artery leads to death (necrosis) of myocardial tissue.

agonal Pertaining to the period of dying.

agonal rhythm A ventricular rate of less than 20 beats/min; this rhythm is seen just before the heart stops beating altogether.

angina pectoris The sudden pain that occurs when the oxygen supply to the myocardium is insufficient to meet demand, causing ischemic changes in the tissue.

aortic aneurysm An outpouching or bulge in the wall of a portion of the aorta, caused by weakening and dilation of the vessel wall; a ruptured aortic aneurysm is life threatening.

arrhythmia The absence of any cardiac rhythm or organized activity; asystole or ventricular standstill.

arteriosclerosis A pathologic condition in which the thickening and stiffening of the arterial walls make the arteries less elastic.

artifact An artificial product; in cardiology, used to refer to noise or interference in an ECG tracing.

asystole The absence of ventricular contraction or electrical activity; a straight-line or flat-line ECG.

atheroma A mass of fatty tissue that gradually calcifies, hardening into an atheromatous plaque that infiltrates the arterial wall, diminishing its elasticity.

atherosclerosis An accumulation of fat inside a blood vessel that narrows the diameter of the lumen.

atrioventricular (AV) junction The portion of the conduction system of the heart that consists of the AV node and the nonbranching portion of the bundle of His.

atrioventricular (AV) node A group of cells that slows the electrical impulses from the sinoatrial node before relaying it to the ventricles; located in the floor of the right atrium immediately behind the tricuspid valve and near the opening of the coronary sinus.

augmented limb leads On an ECG, leads aVR, aVL, and aVF. They contain only one true pole; the other end is a combination of information from other leads. A standard 12-lead ECG consists of the three augmented leads, three standard limb leads, and the six precordial leads.

automated external defibrillator (AED) A smart defibrillator that can analyze the patient’s ECG rhythm, determine whether a defibrillating shock is needed, and guide the user through the resuscitation effort via voice commands.

axis deviation Movement of the heart’s QRS axis to the right or left of its normal position.

Beck triad The classic trio of signs associated with cardiac tamponade: narrowed pulse 

pressure, muffled heart tones, and jugular vein distention.

bifascicular block Blockage of any two fascicles or conduction pathways: a right bundle branch block (RBBB) with anterior hemiblock, RBBB with posterior hemiblock, or anterior hemiblock and posterior hemiblock (a combination known as left bundle branch block).

bigeminy A dysrhythmia in which every other complex is a premature complex, causing a normal–early beat–normal–early beat pattern; can be atrial, junctional, or ventricular.

bipolar leads On an ECG, leads that contain both a positive and a negative pole: leads I, II, and III.

bruits Abnormal whooshing sounds indicating turbulent blood flow within a narrowed vessel; usually heard in the carotid arteries.

bundle branch block (BBB) An intraventricular conduction disturbance involving impedance of electrical impulses from the bundle of His to the right or left bundle branch.

bundle of His The portion of the heart’s conduction system located in the upper portion of the interventricular septum that conducts electrical impulses from the atrioventricular (AV) junction to the right and left bundle branches; also called the AV bundle.

cardiac arrest The cessation of cardiac mechanical activity, as confirmed by the absence of signs of circulation; also called cardiopulmonary arrest.

cardiac cycle The period from one cardiac contraction to the next. Each cardiac cycle consists of ventricular contraction (systole) and relaxation (diastole).

cardiac tamponade A pathologic condition characterized by restriction of cardiac contraction, falling cardiac output, and shock as a result of pericardial fluid accumulation.

cardiovascular disease (CVD) A group of disorders of the heart and blood vessels.

chest compression fraction The period during which compressions are delivered divided by the total time of the resuscitation attempt.

circumflex artery (Cx) One of the two branches of the left main coronary artery; branches of the Cx supply the left atrium, part of the lateral surface of the left ventricle, the inferior surface of the left ventricle in approximately 15% of people, the posterior surface of the left ventricle in 15%, the sinoatrial node in approximately 40%, and the atrioventricular bundle in 10% to 15%.

claudication Pain, cramping, muscle tightness, fatigue, or weakness of the legs during physical activity as a result of increased oxygen demand by the muscle tissue of the legs, hips, and buttocks.

concordant precordial pattern An ECG pattern in which the QRS complexes are all in the same direction in the precordial leads as a result of improper lead placement, anterior wall MI, VT, or other variables.

contiguous leads Leads that view geographically similar areas of the myocardium, such as leads II, III, and aVF; useful for localizing areas of ischemia.

coronary arteries The blood vessels that supply blood to the tissues of the heart.

coronary artery disease (CAD) A pathologic process characterized by progressive atherosclerotic narrowing and eventual obstruction of the coronary arteries.

coronary heart disease (CHD) Disease of the coronary arteries and its associated signs, symptoms, and complications, such as angina pectoris and acute myocardial infarction.

couplet Two consecutive (paired) premature ventricular complexes.

defibrillation The process by which an unsynchronized direct current (DC) electric shock is delivered to the heart to terminate ventricular fibrillation or pulseless ventricular tachycardia.

delta wave The slurring of the upstroke of the first part of the QRS complex that occurs in Wolff- Parkinson-White syndrome.

depolarization The process of discharging resting cardiac muscle fibers by means of an electrical impulse that stimulates contraction.

dissection The process by which the intimal and medial layers of a vessel separate (dissect) after a tear occurs in an aneurysmal portion of the arterial wall. With each ventricular systole, a jet of blood is forced into the torn arterial wall, creating and propagating a false channel.

dysrhythmias Cardiac rhythm disturbances.

ectopic An impulse or rhythm that originates from a site other than the SA node.

electrical conduction system In the heart, the specialized cardiac tissue that initiates and conducts electric impulses; includes the SA node, internodal conduction pathways, atrioventricular node, bundle of His, and the Purkinje network.

endocarditis Inflammation of the endocardium as a result of infection.

fascicular block (hemiblock) Failure of the anterior or posterior fascicles of the heart to conduct electrical impulses because of disease or ischemia.

fibrinolysis The process of dissolving blood clots.

fibrinolytic therapy The use of medications that act to dissolve blood clots.

first-degree AV block A delay in the conduction of the depolarizing impulse from the SA node to the ventricles, prolonging the PR interval; also called first-degree heart block.

heart failure A syndrome that occurs when the heart is unable to pump powerfully enough or fast enough to empty its chambers; as a result, blood backs up into the systemic circuit, the pulmonary circuit, or both.

hyperkalemia A high concentration of potassium in the blood.

hypertension High blood pressure; stage 2 hypertension exists when the systolic blood pressure is 140 mm Hg or higher or the diastolic blood pressure is 90 mm Hg or higher.

hypertensive emergency An acute elevation of blood pressure to 180/120 mm Hg or higher with evidence of end-organ damage (cardiovascular, neurologic, or renal); formerly called hypertensive crisis or malignant hypertension.

hypertensive urgency An acute elevation of BP to 180/120 mm Hg or higher without signs or symptoms of end-organ damage.

hypertrophic cardiomyopathy A genetic condition in which the heart muscle wall is unusually thick, requiring the heart to pump harder to eject blood from the left ventricle.

hypocalcemia A low concentration of calcium in the blood.

hypokalemia A low concentration of potassium in the blood.

idioventricular Related to only the ventricles; produced by the ventricles.

infarction Death (necrosis) of a localized area of tissue caused by ischemia.

internodal pathways The three atrial pathways of electrical conduction that transmit impulses from the sinoatrial node to the atrioventricular node.

ischemia Tissue anoxia caused by diminished blood flow, usually as a result of narrowing or occlusion of an artery.

isoelectric line The baseline of the ECG; isoelectric means neither positive nor negative.

junctional escape rhythm A dysrhythmia arising from the atrioventricular junction with an intrinsic rate of 40 to 60 beats/min; also called junctional rhythm.

lead The electrical potential difference between two points. For example, lead I represents the difference in electrical potential between the right and left arm electrodes.

left anterior descending artery (LAD) One of the two branches of the left main coronary artery; branches of the LAD supply the left ventricle, 

interventricular septum, and part of the right ventricle.

left atrial abnormality Dilation of the left atrium that can occur in patients with valvular heart disease (particularly mitral or aortic valve stenosis), hypertensive disease, cardiomyopathy, or coronary artery disease; it can also occur in an athlete.

left ventricular failure (LVF) A condition in which the left ventricle must work harder to pump blood throughout the body. With systolic failure, the left ventricle does not contract normally and has trouble pumping all the blood in the chamber out to the body; with diastolic failure, the left ventricle contracts normally but has become stiff, impeding its ability to relax and fill with blood between each contraction of the heart.

left ventricular hypertrophy (LVH) A cardiac condition in which the left ventricle becomes enlarged, most often as a result of hypertension.

limb leads The ECG leads attached to the limbs; together, the standard limb leads (I, II, and III) and augmented limb leads (aVR, aVL, and aVF) form the hexaxial reference system along the frontal plane.

long QT syndrome (LQTS) A condition characterized by a QT interval exceeding approximately 0.44 second (440 milliseconds).

Lown-Ganong-Levine syndrome A disorder that causes preexcitation of ventricular tissue and is characterized on ECG by a short PR interval and a normal QRS duration.

lumen The hollow interior space within an artery or other hollow structure.

manual defibrillator A device that requires the paramedic or other trained rescuer to interpret the cardiac rhythm and determine whether defibrillation is needed (rather than relying on a device to make that determination automatically).

microvascular angina A type of angina caused by spasms within the walls of the heart’s smallest coronary arteries.

multifocal Arising from or pertaining to many foci or locations.

myocarditis Inflammation of the myocardium.

necrosis The death of tissue, usually caused by a cessation of its blood supply.

normal sinus rhythm The normal rhythm of the heart that has an intrinsic rate of 60 to 100 beats/min; the rhythm is regular, with minimal variation between R-R intervals, and all measurements are within normal limits.

orthopnea Severe dyspnea experienced when lying down that is relieved by a change in position, such as sitting up or standing.

P wave The first wave of the ECG complex, representing depolarization of the atria.

palpitations The sensation of an abnormally fast or irregular heartbeat.

paroxysmal nocturnal dyspnea (PND) Severe shortness of breath occurring at night after several hours of recumbency, during which fluid pools in the lungs; the person is forced to sit up to breathe; caused by left heart failure or decompensation of chronic obstructive pulmonary disease.

percutaneous coronary intervention (PCI) A minimally invasive procedure performed under fluoroscopic guidance, in which a balloon, stent, or other device is advanced through a peripheral artery catheter and into an obstructed coronary vessel to diagnose and treat coronary artery obstruction.

pericarditis Inflammation of the pericardial sac.

plasmin A naturally occurring clot-dissolving enzyme.

point of maximal impulse (PMI) The palpable beat of the apex of the heart against the chest wall during ventricular contraction; normally palpated at the fifth left intercostal space along the midclavicular line.

PR interval (PRI) The distance between the beginning of the P wave (atrial depolarization) and the beginning of the QRS complex (ventricular 

depolarization), signifying the time required for the atria to depolarize and the excitation impulse to pass through the atrioventricular junction.

precordial leads A term used to describe the chest leads in an ECG.

preexcitation Early depolarization of ventricular tissue through an accessory pathway between the atria and ventricles.

pulmonary edema Congestion of the pulmonary air spaces with exudate and foam, often secondary to left ventricular failure.

pulmonary embolism Obstruction in one or more pulmonary arteries by a solid, liquid, or gas that has swept through the right side of the heart into the lungs.

pulseless electrical activity (PEA) An organized cardiac rhythm (other than ventricular tachycardia) on an ECG monitor that is not accompanied by a detectable pulse.

Purkinje fibers A network of cardiac muscle fibers distributed throughout the ventricular walls’ inner surfaces that conduct the excitation impulse from the bundle branches to the ventricular myocardium.

QRS axis A single vector representing the mean (or average) of all vectors created by the ventricles during depolarization.

QRS complex Deflection of the ECG produced by ventricular depolarization.

reciprocal changes Mirror-image J-point, ST-segment, and T-wave changes seen on the ECG during an ACS.

reentry Spread of an impulse through tissue already stimulated by that same impulse.

refractory period (RP) A short period immediately after depolarization during which the myocytes have not yet repolarized and are unable to fire or conduct an impulse (the absolute refractory period) or have partially repolarized and may depolarize in response to an electrical stimulus (the relative refractory period).

relative refractory period (RRP) The portion of the cardiac action potential that extends from the middle of phase 3 to the beginning of phase 4; during this time, the heart muscle has been partially repolarized and may depolarize in response to an electrical stimulus.

reperfusion therapy Treatment intended to facilitate the resumption of blood flow through a blocked vessel; therapy may be either procedural, such as cardiac catheterization, or pharmacologic, such as administration of a fibrinolytic agent.

rheumatic fever An inflammatory disease caused by streptococcal bacteria; the disease can cause mitral or aortic valve stenosis.

right atrial abnormality Dilation of the right atrium that occurs when returning venous pressure is elevated or pulmonary pressure is high.

right coronary artery (RCA) Artery that provides oxygenated blood to the walls of the right atrium and ventricle, a portion of the inferior part of the left ventricle, and portions of the conduction system.

right ventricular failure (RVF) A condition in which the right side of the heart must work increasingly hard to pump blood into engorged pulmonary vessels; eventually, it cannot keep up with the increased workload.

right ventricular hypertrophy (RVH) A cardiac condition in which the right ventricle becomes enlarged, usually as a result of pulmonary hypertension.

R-R interval The period between the onset of one QRS complex and the onset of the next QRS complex.

scarlet fever A disease caused by the bacterium Streptococcus pyogenes, which is characterized by a sore throat, fever, rash, and “strawberry tongue.”

septum A thick wall that separates the right and left sides of the heart.

sinoatrial (SA) node The dominant pacemaker of the heart, located at the junction of the superior vena cava and the right atrium.

sinus bradycardia A sinus rhythm characterized by a heart rate of less than 60 beats/min.

sinus dysrhythmia A variation of the cycling of a sinus rhythm that is often associated with respiratory cycle fluctuations; the rate increases during inspiration and decreases during expiration.

sinus tachycardia A sinus rhythm characterized by a heart rate greater than 100 beats/min.

ST segment The interval between the end of the QRS complex (the J point) and the beginning of the T wave; when there is significant myocardial ischemia or injury, the ST segment is often depressed or elevated with respect to the isoelectric line.

stable angina Angina pectoris characterized by intermittent pain with a predictable pattern.

subendocardial myocardial infarction A type of acute myocardial infarction in which the ischemic process affects only the inner layer of muscle.

sudden cardiac arrest (SCA) An unexpected cardiac arrest that results in attempts to restore circulation.

sudden cardiac death (SCD) A sudden cardiac arrest in which the resuscitation attempt is unsuccessful.

synchronized cardioversion The use of a synchronized direct current (DC) electric shock to convert a tachydysrhythmia (such as supraventricular tachycardia) to a normal sinus rhythm.

syncope Fainting; brief loss of consciousness caused by transiently inadequate blood flow to the brain.

T wave The upright, flat, or inverted wave following the QRS complex of the ECG, representing ventricular repolarization.

targeted temperature management (TTM) The utilization of cool fluids to get the patient to a targeted hypothermic state during various critical conditions.

thromboembolism A blood clot that initially formed within a blood vessel but is now circulating through the bloodstream.

thrombus A fixed blood clot that can obstruct passage of blood flow through an artery.

transcutaneous pacemaker A device that depolarizes myocardial tissue by sending a small electrical charge through the skin of the chest between one externally placed pacing pad and another.

transcutaneous pacing (TCP) An intervention used to depolarize heart muscle using an external stimulus; pads placed on the patient’s chest deliver electrical energy to the heart, causing muscle contraction.

transmural myocardial infarction A type of acute myocardial infarction in which the infarct extends through the entire wall of the ventricle.

trifascicular block Blockage or impairment of all three components of the ventricular conduction system, with one working occasionally to provide AV conduction.

trigeminy A dysrhythmia in which every third complex is a premature complex, causing a normal– normal–early beat pattern; can be atrial, junctional, or ventricular.

U wave A small, flat wave sometimes seen after the T wave and before the next P wave.

unifocal Arising from a single site.

unstable angina Angina pectoris characterized by a variable, unpredictable pain pattern, which may signal an impending acute myocardial infarction.

Valsalva maneuver Straining or forced exhalation against a closed glottis, the effect of which is to stimulate the vagus nerve, thereby slowing the heart rate.

variant angina A type of angina caused by coronary artery spasm that occurs when a person is at 

rest, when oxygen needs are minimal; also called Prinzmetal angina.

Wolff-Parkinson-White (WPW) syndrome A preexcitation syndrome characterized by a short PR interval, a delta wave, a widened QRS complex, and nonspecific ST-T wave changes, indicating the presence of an accessory pathway.

Remember: This guide provides a foundation. Supplement your learning with textbooks, practice, and real-world experience. Your dedication to continuous learning will benefit your patients and your career.