Electrocardiograph Lab 3

What is Electrocardiograph?

• An Electrocardiogram (ECG) records the electrical signals in the heart.
• It's a common and painless test used to quickly detect heart problems and monitor the heart's health.

Why is ECG done?

• To diagnose many common heart problems, including irregular heart rhythms (arrhythmias), blocked or narrowed arteries in the heart, and previous heart attacks.
• To monitor heart disease treatments, such as pacemakers.

Indications for ECG

• Chest pain
• Dizziness, lightheadedness or confusion
• Heart palpitations
• Rapid pulse
• Shortness of breath
• Weakness, fatigue or a decline in ability to exercise

Heart's Electrical Activity

• The sinoatrial node, located in the right atrium, is the origin of electricity of the heart.
• The electrical activity is sent to the atrioventricular node and then to the purkinjee fibers of the heart.
• Electrically, the most important chamber of the heart is the right atrium.
• Mechanically, the most important chamber of the heart is the left ventricle.

ECG Leads

• Einthoven's triangle has three leads:
  • Lead I: direction of electricity from the right arm to the left arm.
  • Lead II: direction of electricity from the right arm to the left leg.
  • Lead III: direction of electricity from the left arm to the left leg.
• Lead II is important because it directs the electrical pulse from the right atrium to the left ventricle.

Measuring ECG

• Hospitals use 12 electrodes to measure ECG:
  • Right arm, left arm, right leg, left leg, and 8 electrodes between the 4th and 5th ribs on the left and right side of the sternum.
• A single electrode is positioned between the 4th intercostal space.

ECG Waves

• P wave: indicates depolarization of the atrium.
• QRS complex: series of waves that indicate depolarization of the ventricle.
• T wave: represents repolarization of the ventricle.

Important to Know

• The repolarization of the atrium is small and will disappear in QRS complex.
• Gel containing ions can be used to increase conductivity during ECG.
• Sodium is an important electrolyte for the heart movement, and checking the patient's electrolyte levels is important.

What do the Results Tell Us?

• Heart rate: ECG can help identify an unusually fast heart rate (tachycardia) or an unusually slow heart rate (bradycardia).
• Heart rhythm: ECG can detect irregular heartbeats (arrhythmias).
• Heart attack: ECG can show evidence of a previous heart attack or one that's currently happening.
• Blood and oxygen supply to the heart: ECG can provide information about this.
• Heart structure changes: ECG can provide clues about an enlarged heart, heart defects, and other heart problems.

What is Electroencephalogram (EEG)?

• An EEG is a test that measures electrical activity in the brain using small metal discs (electrodes) attached to the scalp.

What Does EEG Record?

• The waveforms recorded by EEG reflect the activity of the surface of the brain and brain cortex.
• EEG records electrical impulses of the brain sent via electrodes placed on the head to an amplifier.

Types of Brain Waves

Delta Waves

• Frequency: 3 Hz or below
• Highest in amplitude and slowest waves
• Normal in infants up to one year and in stages 3 and 4 of sleep

Theta Waves

• Frequency: 3.5 to 7.5 Hz
• Classified as "slow" activity
• Normal in children up to 13 years and in sleep, but abnormal in awake adults

Alpha Waves

• Frequency: 7.5 to 13 Hz
• Usually seen in posterior regions of the head on both sides
• Appears when closing the eyes and relaxing, and disappears when opening the eyes or alerting

Beta Waves

• Frequency: 14 Hz and greater
• Classified as "fast" activity
• Seen on both sides in symmetrical distribution, most evident frontally
• Accentuated by sedative-hypnotic
• Regarded as a normal rhythm
• Dominant rhythm in patients who are alert or anxious or have their eyes open

Why is an EEG Performed?

• To check the status of brain-related conditions such as epilepsy.

What is Electromyography?

• Electromyography (EMG) is a diagnostic procedure to assess the health of muscles and motor neurons.
• EMG results can reveal nerve dysfunction, muscle dysfunction, or problems with nerve-to-muscle signal transmission.

How EMG Works

• Motor neurons transmit electrical signals that cause muscles to contract.
• EMG uses tiny devices called electrodes to translate these signals into graphs, sounds, or numerical values.

Why EMG is Done

• Doctors order an EMG if patients show signs or symptoms of nerve or muscle disorders, such as:
  • Tingling
  • Numbness
  • Muscle weakness
  • Muscle pain or cramping
  • Certain types of limb pain

Types of EMG Electrodes

• There are two major types of electrodes used to measure EMG signals:
  • Needle electrodes: approximately 1 mm2 wide, inserted into the muscle to be tested
  • Surface electrodes: 0.5–2.5-cm wide, non-invasive, and positioned to detect electrical activity that activates muscle movement

What EMG Results Detect

• EMG results help diagnose or rule out conditions such as:
  • Muscle disorders (e.g., muscular dystrophy)