CJ

Cardiac Rhythm Recognition & Treatment Modalities

Cardiac Rhythm Recognition & Treatment Modalities

  • Course: NURS 4111 – Adult Health Nursing at Georgia Southern University

  • Instructor: Kimberly J. Burke, MSN-Ed, RN, CCRN, SCRN

Course Expectations

  • Learning Objectives:

    • Understanding Electrical Pathway of the Heart.

    • Normal Limits of ECG Tracing.

    • Recognition of Heart Rhythms:

    • Normal Sinus Rhythm

    • Sinus Bradycardia

    • Sinus Tachycardia

    • Atrial Fibrillation

    • Atrial Flutter

    • Premature Ventricular Contractions (PVC’s)

    • Ventricular Tachycardia (V Tach)

    • Ventricular Fibrillation (V Fib)

    • Atrioventricular Blocks

    • Treatment Modalities for Life-Threatening Dysrhythmias.

Electrical Activity of the Heart

  • Diagram:

    • Includes nodes like Sinoatrial Node and Atrioventricular Node, the Bundle of His, and Purkinje Fibers.

ECG - Electrocardiogram

  • Definition:

    • A tracing of the electrical activity of the heart recorded on graph paper, showing parts like P Wave, QRS Complex, T Wave, and intervals: PR, ST, and QT.

Key Definitions

  • Lead:

    • A view of the electrical activity of the heart from a specific body angle.

    • Concept: Lead = Picture of electrical activity.

  • Electrode:

    • Equipment used to obtain leads or pictures of electrical activity.

    • 12-Lead EKG is obtained from 10 electrodes:

    • 4 Limb Leads

    • 6 Precordial Leads.

Electrode Placement

  • 5 Lead Electrode Placement:

    • RA (White): Near right mid-clavicular line below the clavicle.

    • LA (Black): Near left mid-clavicular line below the clavicle.

    • V (Brown): Right of sternum at the 4th intercostal space.

    • RL (Green): Between the 6th & 7th intercostal space on the right mid-clavicular line.

    • LL (Red): Between the 6th & 7th intercostal space on the left mid-clavicular line.

12-Lead Configuration

  • 12 Pictures of electrical activity from various leads (I-III and aVR, aVL, aVF as vertical; V1-V6 as horizontal).

  • Coronary Anatomy & ECG Leads

    • Lateral Leads: I, aVL, V5-V6

    • Inferior Leads: II, III, aVF

    • Anterior/Septal Leads: V1-V4.

Nursing Process Related to ECG

  • Assessment: Evaluate ECG to understand how the heart functions electrically.

  • Diagnosis: Determine if the ECG is normal or abnormal.

  • Interventions: Vary based on rhythm and symptoms detected.

  • Evaluation: Reassess to determine treatment efficacy.

ECG Timing and Measurement

  • Small square in the ECG tracing represents 0.04 seconds; 0.2 seconds shows 5 small squares.

  • A 6-second strip can be analyzed to assess heart rate.

Interpretation of ECG Components

  1. P WAVE (0.06-0.12 seconds):

    • Represents atrial depolarization (contraction).

  2. PR INTERVAL (0.12-0.20 seconds):

    • Duration for impulse to travel from atria to ventricle.

  3. QRS COMPLEX (<0.12 seconds):

    • Represents ventricular depolarization (contraction).

  4. ST SEGMENT:

    • Indicates the time between ventricular depolarization and repolarization.

  5. T WAVE (0.16 seconds):

    • Time for ventricular repolarization.

  6. QT INTERVAL (0.36-0.44 seconds):

    • Total time for the electrical activity from ventricular depolarization to repolarization.

  • Torsades de Pointes: Can occur due to prolonged QT interval caused by hypercalcemia or Digoxin use.

Steps to Determine Heart Rhythm

  • Assessment Steps:

    • Determine rate and rhythm (regular vs. irregular).

    • Analyze present P waves.

    • Measure the P-R interval and the QRS complex.

Heart Rate Calculation Methods

  • 6-sec Strip Method: Count QRS complexes in 6 seconds, then multiply by 10.

  • R-R Interval Method: Count small squares between two R-R intervals, divide by 1500.

  • Large Squares Method: Count large squares between two R-R intervals, divide by 300.

Sinus Rhythms

  • Normal Sinus Rhythm (NSR):

    • Rate: 60-100 bpm

    • Rhythm: Regular, consistent P-P and R-R intervals.

    • PR Intervals: 0.12 to 0.20 seconds.

    • QRS Duration: 0.04 to 0.12 seconds.

  • Sinus Bradycardia:

    • Rate: Less than 60 bpm.

    • Treatment: Assess the patient. If symptomatic, therapy includes Atropine IV (0.5 mg bolus, may repeat every 3-5 min, max 3 mg) or transcutaneous pacing.

  • Sinus Tachycardia:

    • Rate: Greater than 100 bpm, potentially up to 150 bpm.

    • Treatment: Assess the patient and treat underlying causes if sustained rates exceed 150 bpm.

Rhythms Originating in the Atria

  • Premature Atrial Contractions (PACs):

    • Causes include stress, caffeine, alcohol, etc.

    • EKG features with early sinus beat; the rhythm may be irregular.

    • Treatment based on symptoms, may involve beta-blockers.

  • Atrial Fibrillation:

    • Rate: Typically varies but ventricular rate could be over 80.

    • Rhythm: Irregular with no detectable P waves.

    • Treatment: Depends on whether it is controlled (rate <100 and asymptomatic) or uncontrolled (rate >100 and/or symptomatic).

  • Atrial Flutter:

    • Rate: Example shows 70 bpm.

    • P Waves: Flutter waves are present; no P waves.

    • Treatment: Varies based on symptoms; oxygen is crucial.

    • Cardioversion and antiarrhythmic treatments may be employed depending on stability.

Rhythms Near the Junction

  • Junctional Rhythm:

    • Rate: Typically 40-60 bpm, can vary.

    • P Waves: May be absent, inverted, or follow QRS.

  • Supraventricular Tachycardia (SVT):

    • Rate: 150-220 bpm, rhythm regular.

    • Treatment involves vagal maneuvers and medication like adenosine or beta-blockers for stable cases.

Ventricular Dysrhythmias

  • Premature Ventricular Contractions (PVCs):

    • Characteristics: Wide, bizarre QRS complexes. Treatment depends on occurrence frequency and symptoms.

    • Nursing Considerations: Assess frequency, monitor hemodynamic stability, and identify correctable causes like electrolyte imbalance.

  • Ventricular Tachycardia (V Tach):

    • Rate: 150-250 bpm; it's life-threatening.

    • Treatment: Oxygen, Amiodarone, potentially synchronized cardiovert if compromised.

  • Torsades de Pointes:

    • Life-threatening arrhythmia, often with a prolonged QT interval.

    • Treatment includes magnesium sulfate infusion, addressing potential electrolyte imbalances, and correct any reversible causes (e.g., medications causing the prolonged QT).

  • Ventricular Fibrillation (V Fib):

    • Chaotic rhythm, life-threatening, no identifiable pattern.

    • Treatment: High-quality CPR, immediate defibrillation.

Atrioventricular Blocks & Asystole

  • 1st Degree AV Block:

    • PRI: > 0.20 seconds (prolonged). Treatment: None if stable.

  • 2nd Degree AV Block - Type I (Wenckebach):

    • PRI: Lengthens incrementally until a QRS is dropped. Risk from symptomatic presentation.

  • 2nd Degree AV Block - Type II (Mobitz II):

    • Constant PRI with sudden dropped QRS complexes. Treatment: Often requires pacemaker if symptomatic.

  • 3rd Degree (Complete) AV Block:

    • Rhythm: Atria and ventricles function separately. Requires pacemaker for symptomatic treatment.

  • Asystole:

    • Treatment: Confirm rhythm in two leads, initiate high-quality CPR, administer Epinephrine per ACLS guidelines.

Advanced Cardiac Interventions

  • Pacemakers:

    • Maintain adequate heart rate and cardiac output when SA/AV nodes fail. Types include temporary and permanent systems.

  • Defibrillation:

    • Aimed at pulseless VT/VF using an unsynchronized shock. Not to be used for asystole.

  • Synchronized Cardioversion:

    • Delivers shock timed with the R wave, used for unstable A fib, flutter, or SVT.