Recording-2025-02-07T17:42:53.661Z

Calculating Heart Rate from EKG

• Heart Rate Calculation

  • Important for assessing rhythms such as sinus bradycardia (below 60 bpm) and sinus tachycardia (above 100 bpm).

  • Measure R-R interval on an EKG strip.

  • Count the large boxes between two R waves.

  • Formula: Heart Rate = 300 / Number of Large Boxes between R waves.

• R Waves

  • Each peak corresponds to ventricular depolarization.

  • A cycle of one R-R interval corresponds to one heartbeat.

• Heart Rate Values

  • Normal heart rate should fall between 60 to 100 bpm.

  • For tachycardia, if the calculated heart rate is over 100 bpm, it indicates a faster heart rhythm.

EKG Rhythms

• Sinus Rhythms

  • Assess if there is a P wave before each QRS complex.

  • Normal PR interval: 0.12 to 0.20 seconds (less than 1 large box) and consistent in each cycle.

  • Assess QRS duration – should be narrow (less than 0.12 seconds).

• Normal Sinus Rhythm

  • Regular R-R intervals.

  • P wave present before every QRS.

  • Maintain normal heart rate and PR interval.

• Sinus Bradycardia

  • Everything is normal except for heart rate < 60 bpm.

  • Common in athletes or during sleep; may be symptomatic.

  • Symptoms can include: dizziness, syncope (fainting), lethargy.

  • Treatments may include atropine or pacing.

• Sinus Tachycardia

  • Regular rhythm with heart rate > 100 bpm.

  • P wave present before each QRS.

  • Symptoms may include anxiety or a pounding heart.

  • Potential causes: fever, hypoxia, pain.

Lead Placement and EKG Configuration

• Y-Lead EKG (Einthoven's Triangle)

  • Lead I: Right arm negative, left arm positive.

  • Lead II: Right arm negative, left leg positive.

  • Lead III: Left arm negative, left leg positive.

  • Primarily used in emergency situations or critical care settings.

• Precordial Leads

  • Unipolar: V1 to V6.

  • Placement:

    • V1: Fourth intercostal space, right side of sternum.

    • V2: Fourth intercostal space, left side of sternum.

    • V3: Midway between V2 and V4.

    • V4: Fifth intercostal space, midclavicular line.

    • V5: Anterior axillary line, same level as V4.

    • V6: Midaxillary line, same level as V4.

Basic EKG Interpretation

• Regular Rhythm Assessment

  • Check R-R intervals for consistency.

  • Count large boxes between R waves and confirm each interval is similar.

• EKG Competency

  • Recognizing normal values is crucial.

  • Familiarity with EKG lead placements, rhythms and their meanings is essential for practice.

Atrial Fibrillation (AFib) and Atrial Flutter

• Atrial Fibrillation (AFib)

  • Irregular rhythm with no clear P waves (chaotic baseline).

  • Common arrhythmia; can cause palpitations and shortness of breath.

  • Treatment focuses on rate control (e.g., beta blockers) and anticoagulation to prevent clots.

• Atrial Flutter

  • Regular rhythm characterized by sawtooth P waves (also known as "F-waves").

  • Heart rate can be rapid but remains synchronized.

  • Treatment strategies include rate control and potential anticoagulation.

Summary of Rhythms and Characteristics

• Regularity

  • Sinus bradycardia: Heart rate < 60 bpm, normal rhythm characteristics.

  • Sinus tachycardia: Heart rate > 100 bpm, maintains normal EKG features.

  • AFib: Irregular with chaotic baseline, irregular R-R intervals.

  • Atrial flutter: Regular with distinct P wave patterns but faster rate.

Understanding these concepts is crucial for accurate EKG interpretation and effective patient assessment.