Podcast
Questions and Answers
During ventricular repolarization, which wave on an ECG/EKG would you expect to observe?
During ventricular repolarization, which wave on an ECG/EKG would you expect to observe?
- QRS Complex
- T-Wave (correct)
- Q-Wave
- P-Wave
If the paper speed of an ECG is set at 25 mm/s and the distance between two R peaks is measured to be 20 mm, what is the approximate heart rate?
If the paper speed of an ECG is set at 25 mm/s and the distance between two R peaks is measured to be 20 mm, what is the approximate heart rate?
- 80 beats/min
- 90 beats/min
- 75 beats/min (correct)
- 60 beats/min
In the context of ECG limb lead placement, which color is typically associated with the right leg electrode, which serves as the earth lead?
In the context of ECG limb lead placement, which color is typically associated with the right leg electrode, which serves as the earth lead?
- Yellow
- Black
- Red (correct)
- Green
According to Einthoven's triangle, which of the following statements accurately describes Lead I?
According to Einthoven's triangle, which of the following statements accurately describes Lead I?
What is a key characteristic of augmented vector (aV) leads in electrocardiography?
What is a key characteristic of augmented vector (aV) leads in electrocardiography?
For standard 12-lead electrocardiography, where is the V4 precordial electrode placed?
For standard 12-lead electrocardiography, where is the V4 precordial electrode placed?
To obtain a hexaxial (6-axis) view of the heart, which lead systems are combined?
To obtain a hexaxial (6-axis) view of the heart, which lead systems are combined?
What is the primary effect of acetylcholine (ACh) released by parasympathetic nerves on heart rate?
What is the primary effect of acetylcholine (ACh) released by parasympathetic nerves on heart rate?
Which of the following is characteristic of heart rate variability (HRV)?
Which of the following is characteristic of heart rate variability (HRV)?
What does increased parasympathetic input typically indicate in terms of heart rate variability (HRV)?
What does increased parasympathetic input typically indicate in terms of heart rate variability (HRV)?
During exercise, what changes in sympathetic tone and HRV would you expect to observe?
During exercise, what changes in sympathetic tone and HRV would you expect to observe?
Which physiological state is most appropriate for measuring heart rate variability (HRV) to obtain reliable data?
Which physiological state is most appropriate for measuring heart rate variability (HRV) to obtain reliable data?
What is the typical direction of electrical current flow in the heart, starting from the sinoatrial (SA) node?
What is the typical direction of electrical current flow in the heart, starting from the sinoatrial (SA) node?
What does the QRS complex represent on an electrocardiogram (ECG)?
What does the QRS complex represent on an electrocardiogram (ECG)?
On an ECG, what does the PR interval represent?
On an ECG, what does the PR interval represent?
In bipolar limb leads, describe the direction of electrical potential measured in Lead III.
In bipolar limb leads, describe the direction of electrical potential measured in Lead III.
If the sum of AVR + AVL + AVF does NOT equal 0, what does this indicate?
If the sum of AVR + AVL + AVF does NOT equal 0, what does this indicate?
Where is the V1 chest lead positioned?
Where is the V1 chest lead positioned?
What is the primary influence of epinephrine/norepinephrine on heart rate?
What is the primary influence of epinephrine/norepinephrine on heart rate?
Which of the following is true regarding heart rate variability (HRV)?
Which of the following is true regarding heart rate variability (HRV)?
Flashcards
Electrocardiography (ECG)
Electrocardiography (ECG)
Records the heart's electrical activity.
Heart Rate Variability (HRV)
Heart Rate Variability (HRV)
Measures the heart's beat-to-beat variations.
SA node
SA node
Initiates electrical impulses in the heart.
AV node
AV node
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Purkinje fibers
Purkinje fibers
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P-Wave
P-Wave
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QRS Complex
QRS Complex
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T-Wave
T-Wave
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PR Interval
PR Interval
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QRS Duration
QRS Duration
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Calculating Heart Rate
Calculating Heart Rate
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Right Arm (RA)
Right Arm (RA)
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Left Arm (LA)
Left Arm (LA)
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Right Leg (RL)
Right Leg (RL)
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Left Leg (LL)
Left Leg (LL)
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Bipolar Limb Leads
Bipolar Limb Leads
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Unipolar Limb Leads
Unipolar Limb Leads
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V1 Placement
V1 Placement
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Increased HRV effects
Increased HRV effects
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R-R Interval
R-R Interval
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Study Notes
- Lab 2 focuses on electrocardiography (ECG) and heart rate variability (HRV).
Heart - Electrical Activity
- Electrical current flows in a specific direction within the heart:
- Starts at the SA node
- Moves to the atria
- Then to the AV node
- Proceeds to the Purkinje fibers
- Finally, reaches the ventricles
Electrocardiogram (ECG/EKG)
- Various segments represent specific events, including:
- P-Wave signifies atrial depolarization
- The QRS complex indicates atrial repolarization and ventricular depolarization
- The T-Wave shows ventricular repolarization
ECG Trace
- Enables time and voltage measurement
- Vertical axis: 1 small square = 1 mm (0.1 mV); 1 large square = 5 mm (0.5 mV); 2 large squares = 10 mm (1.0 mV)
- Horizontal axis: 1 small square = 0.04 s; 1 large square = 0.2 s; 5 large squares = 1.0 s
ECG - Calculating Heart Rate
- To calculate heart rate:
- Determine paper speed: 25 mm/s, where 25 mm of activity equals 1 second.
- Measure the distance between R peaks.
- Use the formula: (Paper speed / R-R distance) x 60 to get HR in beats per minute.
Limb Leads - Placement
- Limb leads placement uses specific colors for each limb:
- Right Arm: Black
- Left Arm: Green
- Right Leg: Red (Earth Lead)
- Left Leg: Yellow
Limb Leads & Einthoven’s Triangle
- Provides a spatial orientation for ECG measurement.
Bipolar Limb Leads
- Lead I: RA (-) to LA (+)
- Lead II: RA (-) to LL (+)
- Lead III: LA (-) to LL (+)
Unipolar Limb Leads
- Augmented (a) Vector (V) Leads
- aVR (Right)
- aVL (Left)
- aVF (Front)
- Low amplitude, so they are magnified by 50%.
- The sum of voltages for P, QRS, and T equals 0 V.
- The sum of AVR + AVL + AVF equals 0.
Limb Leads - Spacial Representation
- Offers a spatial view of the leads
Precordial (Chest) Leads – Placement
- Shows location of chest leads
Precordial (Chest) Leads – Placement
- Specific placement and color codes:
- V1: 4th intercostal space (right sternal border), Red
- V2: 4th intercostal space (left sternal border), Yellow
- V3: Midpoint between V2 & V4, Green
- V4: 5th intercostal space (midclavicular line), Brown
- V5: Horizontal to V4 (anterior axillary line), Black
- V6: Horizontal to V4 (mid axillary line), Purple
Chest Leads - Spacial Representation
- Diagrammatic representation of chest lead placement
Hexaxial Lead Diagram
- A combined unipolar and bipolar lead system forms a hexaxial view of the heart.
Heart Rate Variability (HRV)
- HRV is the time between R-R intervals
- Can determine the health of your heart among other things
Control of Heart Rate
- Several mechanisms control heart rate:
- Autonomic input (afferent & effect nerves)
- Hormones (Acetylcholine (Ach), epinephrine (Epr), norepinephrine (NEpr))
- Feedback from chemoreceptors
- Feedback from baroreceptors
Autonomic Control of Heart Rate
- Autonomic Nervous System (ANS):
- Parasympathetic nerves: Acetylcholine (Ach), slows heart down
- Sympathetic nerves: Epinephrine/Norepinephrine, speeds heart up, and increases strength of contraction
What is HRV?
- HRV refers to the variance in time between R-R intervals.
- A healthy heart is dynamic and responsive to physiological changes, while an unhealthy heart is less responsive
What Does HRV Tell Us?
- HRV indicates the balance between sympathetic and parasympathetic influence on the heart
- Increased parasympathetic input leads to increased HRV
- Decreased parasympathetic input leads to decreased HRV
Heart Rate Variabilty
- Increased HRV/Parasympathetic activation reflects recovery from exercise/training status/adaptation.
- Relative HRV can be determined on condition
- Rest = Increased Parasympathetic Tone/Decreased Sympathetic Tone/Increased HRV
- Exercise = Decreased Parasympathetic Tone/Increased Sympathetic Tone/Decreased HRV
- Recovery = Increased Parasympathetic Tone/Decreased Sympathetic Tone/Increased HRV
How Should We Measure HRV?
- Resting standardized conditions, preferably upon awakening.
- Avoid measuring during or post-exercise due to high dependency on exercise intensity.
- Measuring during daily activities may not provide standardized results.
How CAN We Measure HRV?
- HR sensor (Bluetooth) paired with a smartphone.
- Photoplethysmography can also be used
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