ECG

EKG Demonstration Notes

Objective

Learn the fundamental concepts of EKG interpretation, focusing specifically on the identification of rhythms and dysrhythmias that are prevalent in clinical practice settings, particularly in critical care environments.

Chapter Overview

Focus on Chapters 28 and 29 of the designated textbook or material. Supplemental materials will be provided for thorough review, including detailed charts, instructional videos, and interactive quizzes that reinforce learning objectives and practical application of concepts.

EKG Basics

Understanding the EKG Paper

  • Small Box: 0.04 seconds. Each small box represents a brief interval, crucial for timing assessment in the rhythm.

  • Large Box: 0.20 seconds (equivalent to 5 small boxes). This provides a broader perspective for measuring slower rhythms. Understanding timing is key for accurate EKG interpretation and identifying abnormalities.

Learning Objectives

  1. Normal EKG Identification: Recognize the standard waveforms on an EKG:

    • P Wave: Represents atrial depolarization.

    • QRS Complex: Represents ventricular depolarization and is crucial for assessing the heart's pumping function.

    • T Wave: Represents ventricular repolarization.

  2. Heart Rate and Rhythm Calculation: Understand how to calculate heart rate using methods such as counting R-R intervals or using 6-second strips, critical for assessing cardiac function.

  3. Dysrhythmia Recognition: Acknowledge and understand common dysrhythmias, especially Atrial Fibrillation (AFib), its characteristics, and significance in patient care.

  4. Lethal Rhythms Identification: Identify lethal rhythms like ventricular fibrillation (V-fib), ventricular tachycardia (V-tach), and asystole, understanding their urgency and appropriate interventions.

  5. Patient Perfusion Significance: Appreciate the impact of adequate patient perfusion on overall health and the role fluids and electrolytes play in maintaining normal cardiac function.

Key Electrolytes for Cardiac Function

  • Potassium: Normal level is between 3.5-5.0 mEq/L. Potassium is critical for maintaining the electrical activity of the heart.

    • Hypokalemia: Low potassium levels can lead to arrhythmias such as premature ventricular contractions (PVCs).

    • Hyperkalemia: High potassium can cause potentially life-threatening conditions like peaked T-waves or asystole. Continuous monitoring is essential in high-risk patients.

Clinical Scenario and Importance of EKG

  • Discuss the chaotic and high-stress environment of Intensive Care Units (ICUs). Rapid changes in a patient’s condition can influence heart rhythms significantly, necessitating skilled EKG interpretation.

  • Share real-life experiences where monitoring patients for dysrhythmias led to timely interventions, emphasizing the importance of systematic assessment and maintaining situational awareness in critical care. This includes understanding the limitations and potentials of EKG monitoring technology.

Cardiac Conduction System

  • Primary Pacemaker: The SA node (sinoatrial node), located in the right atrium, is responsible for initiating electrical impulses that dictate heart rhythm. It influences heart rate through autonomic nervous system modulation.

    • Normal Heart Rate: 60-100 beats per minute. Rates outside this range may indicate underlying pathology.

    • Nervous System Influence: The sympathetic nervous system typically increases heart rate in stressful situations, while the parasympathetic nervous system reduces heart rate during rest.

  • Atrioventricular (AV) Node and Bundle of His: These components are responsible for delaying the electrical impulse momentarily, allowing the atria to contract and empty blood into the ventricles before ventricular contraction begins.

Terminology in Cardiac Physiology

  • Automaticity: Refers to the ability of pacemaker cells to spontaneously generate electrical impulses without external stimuli, vital in maintaining heart rhythm.

  • Excitability: This is the capacity of non-pacemaker cells to respond to electrical impulses, a fundamental property that allows the heart to contract.

  • Conductivity: The ability of cardiac muscle to conduct impulses effectively throughout the heart, ensuring synchronized contractions.

  • Contractility: Reflects the power of cardiac muscle contractions, influenced by factors like stretch (preload) and vascular resistance (afterload), critical in understanding cardiac output.

EKG Lead Application

  • Proper lead placement is crucial for accurate EKG readings.

    • Preparation: Ensure the skin is clean, dry, and hair is shaved if necessary for optimal electrode contact.

    • Stability: Utilize adhesive tape or other methods to secure leads in place and prevent movement artifacts that can distort readings.

EKG Strip Interpretation Steps

  1. Identify Heart Rate: Calculate using 6-second strips or assess R-R intervals; recognize if heart rate falls within a normal range of 60-100 bpm.

  2. Check Rhythm Regularity: Evaluate if the intervals are consistent, which indicates a regular rhythm; variability may indicate arrhythmias.

  3. Identify P Waves: Confirm that each QRS complex is preceded by a P wave, anomaly in this sequencing can indicate atrial abnormalities.

  4. Evaluate PR Interval: The normal duration is 0.12 to 0.20 seconds, indicating proper conduction through the AV node; prolonged intervals could suggest Atrioventricular blocks.

  5. Assess QRS Complex: Normal range is 0.06 to 0.10 seconds; a wider QRS complex may indicate bundle branch block or ventricular origin rhythms.

  6. Examine ST Segment: Look for deviations from baseline, elevations may indicate myocardial injury, and depressions can indicate ischemia; these changes are critical for diagnosing cardiac events.

Common Dysrhythmias

  1. Atrial Fibrillation (AFib): A disorganized rapid rhythm with no discernible P waves, placing patients at increased risk for thromboembolic events such as strokes; rate can be controlled using medications or electrical cardioversion when symptomatic.

  2. Ventricular Tachycardia (Vtach): Characterized by a faster heart rate between 140-180 bpm. Assessment includes determining pulse presence; pulseless Vtach is a critical emergency that demands immediate defibrillation and ACLS protocol adherence. V give them the D

  3. Ventricular Fibrillation (Vfib): This life-threatening emergency leads to ineffective heart quivering without any effective blood flow, requiring immediate defibrillation and advanced cardiac life support (ACLS) protocols to restore normal rhythm. V give them the D.

  4. Ventricular Asystole: The complete lack of electrical activity in the heart; immediate intervention with CPR and administration of adrenaline per ACLS guidelines is crucial as this condition is incompatible with life.

Management of Dysrhythmias

  • Initial Actions: Before any interventions based on EKG findings, performing a comprehensive patient assessment is essential including vital signs and symptoms.

  • Equipment: Familiarize oneself with the use of pacemakers, EKG monitors, and defibrillators to enhance team response and patient outcomes in critical scenarios.

  • Medications:

    • Adenosine: Used for treating Supraventricular Tachycardia (SVT); a rapid 6mg IV push may be necessary, with a follow-up bolus of 12mg if there’s no response.

    • Anticoagulants: Preferred agents for managing AFib include newer options like Eliquis and Sorelto which provide ease of use compared to warfarin due to fewer dietary restrictions and reduced need for monitoring.

Importance of Assessing the Patient

  • Always integrate the patient’s clinical picture when interpreting EKG results. An understanding of the broader clinical context, including associated symptoms (e.g. dizziness, chest pain), is vital; these can provide insight into urgent patient needs and guide intervention.

Conclusion

  • Reiterate the importance of comprehensive patient assessment and consistent monitoring in the timely recognition and management of dysrhythmias. Stay prepared through practical exercises in lead application and EKG interpretation to bolster expertise in clinical practice.

  • Warfarin is 2-3 therapeutic range

Practical Exercises

Conduct practical sessions aimed at improving lead placement accuracy and proficiency in rapid EKG interpretation. Encourage feedback and discussion to enhance collaborative learning in interpreting complex readings.