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Questions and Answers
What is considered a normal heart rate?
What is considered a normal heart rate?
- 70-110 BPM
- 60-100 BPM (correct)
- 50-70 BPM
- 80-120 BPM
What condition is indicated by a heart rate less than 60 BPM?
What condition is indicated by a heart rate less than 60 BPM?
- Bradycardia (correct)
- Normal sinus rhythm
- Arrhythmia
- Tachycardia
How can you quickly estimate the heart rate from the ORS complexes?
How can you quickly estimate the heart rate from the ORS complexes?
- Count the ORS complexes and multiply by 4
- Count the ORS complexes and multiply by 6 (correct)
- Count the ORS complexes and multiply by 10
- Count the ORS complexes and multiply by 2
What does a heart rate greater than 100 BPM indicate?
What does a heart rate greater than 100 BPM indicate?
What characterizes a sinus rhythm?
What characterizes a sinus rhythm?
What term is used to describe a heart rate greater than 100 beats per minute?
What term is used to describe a heart rate greater than 100 beats per minute?
What is the normal range for the PR Interval?
What is the normal range for the PR Interval?
Which rhythm is characterized by an irregular heart rate?
Which rhythm is characterized by an irregular heart rate?
What is the maximum length for a normal QT Interval in females?
What is the maximum length for a normal QT Interval in females?
Which condition is indicated by a heart rate of 60 beats per minute or less?
Which condition is indicated by a heart rate of 60 beats per minute or less?
What does the P wave on an ECG represent?
What does the P wave on an ECG represent?
Which component of the ECG is associated with ventricular repolarization?
Which component of the ECG is associated with ventricular repolarization?
What is the approximate duration of one large box on an ECG?
What is the approximate duration of one large box on an ECG?
Which wave reflects the repolarization of Purkinje fibers?
Which wave reflects the repolarization of Purkinje fibers?
What is the vertical length of the QRS complex in a large box on an ECG?
What is the vertical length of the QRS complex in a large box on an ECG?
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Study Notes
ECG Basics
- Sinoatrial node (Puran) initiates the heart's electrical impulses; cycle duration is 0.20 seconds.
- Horizontal length of a large box on ECG paper equals 0.20 seconds; useful for timing.
- Vertical height of QRS complex on a large box measures 5mm, indicating the amplitude of ventricular depolarization.
Waves and Segments
- P wave indicates atrial depolarization, a crucial phase for heart contraction.
- QRS complex represents ventricular depolarization, a key component of heart activity.
- ST segment reflects the period when the ventricles are contracting and emptying.
- T wave signifies ventricular repolarization, restoring the resting state.
- U wave may represent Purkinje fiber repolarization, appearing occasionally after the T wave.
Heart Rate
- Normal heart rate ranges from 60 to 100 beats per minute (BPM).
- Bradycardia occurs when the heart rate drops below 60 BPM.
- Tachycardia is identified when the heart rate exceeds 100 BPM.
- To estimate heart rate:
- Count the number of QRS complexes over 6 seconds and multiply by 10.
- Alternatively, use the formula: Rate = 60 / (R-R interval time).
- Another method: Rate = 300 / (number of large boxes between R-R intervals).
Rhythm Assessment
- Sinus rhythm: Waves occur in consistent positions.
- Sinus Tachycardia: Heart rate exceeds 100 BPM, with regular P waves preceding each QRS complex.
- Sinus Bradycardia: Heart rate is at or below 60 BPM, with regular rhythm.
- Sinus Arrhythmia: Irregular heart pattern observed despite normal structure.
Other Rhythms
- Atrial Fibrillation: Irregular and often rapid heart rate originating from chaotic electrical signals.
- Atrial Flutter: Regular but rapid heart rhythm due to reentrant circuits in the atria.
- Premature Atrial Contraction (PAC): Extra heartbeats originating in the atria.
- Premature Ventricular Contraction (PVC): Extra heartbeats originating in the ventricles.
Intervals and Durations
- PR Interval: Normal duration is between 0.12 to 0.20 seconds, reflecting atrial depolarization and conduction through the AV node.
- QRS Duration: Ranges from 0.07 to 0.10 seconds; indicates the time taken for ventricular depolarization.
- QT Interval is critical for assessing the heart's electrical recovery:
- Normal duration is ≤0.44 seconds.
- Males: ≤0.45-0.46 seconds.
- Females: ≤0.47-0.48 seconds.
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