Term | Definition |
Location of the heart | In the left side of the thoracic cavity |
Pericardium | Contains a lubricating fluid that reduces friction as the heart beats - outer layer of the heart |
Epicardium | Forms the innermost layer of the pericardium and the outer surface of the heart - serous membrane |
Myocardium | The middle layer of the heart wall - made of muscle tissue |
Endocardium | Lines the inside of the heart chambers and forms the surface of the valves - thin, smooth membrane |
How many chambers are in the heart? | 4 chambers
2 atria (on top)
2 ventricles (on bottom)
2 Atrioventricular valves (between atria and ventricles)
2 Semilunar valves ( between ventricles and blood vessels) |
Order of blood flow - body to lungs | Superior and inferior vena cava (from the body) -> Right atrium -> tricuspd valve -> right ventricle -> pulmonary valve -> pulmonary artery (to the lungs) |
Order of blood flow - lungs to body | pulmonary veins (from the lungs) -> left atrium -> bicuspid (mitral) valve) -> left ventricle -> aortic valve -> aorta (to the body) |
Pulmonary circulation | The blood flow between the heart and the lungs |
Systemic circulation | The blood flow between the heart and cells of the body |
Atria | The top two heart chambers where the blood enters the heart through |
Right Atrium | Receives deoxygenated blood from the body through the superior and inferior vena cava |
Right Ventricle | Contracts to send blood to through the pulmonary artery to the lungs |
Left Atrium | Receives oxygenated blood from the lungs through the pulmonary veins |
Left Ventricles | Contracts to send blood through the aorta to the body |
Purpose of heart valves | To keep blood flowing on only one direction |
Electrical impulse path | Sinoartial (SA) node -> atria -> atrioventricular (AV) node -> bundle of HIS -> purkinje fibers -> ventricles |
SA node | The body's natural pacemaker |
Muscle contraction | Caused by electrical impulses in the heart |
Systole | The contraction phase of a heart beat |
Atrial depolarization | When the impulse starts in the SA node and causes the atria to contract |
Ventricle depolarization | When the impulse moves through the AV node, bundle of His, and purkinje fibers and causes the ventricles to contract. |
Repolarization | Time of electrical recovery in the ventricles before the cycle starts |
Electrocardiogram (ECG) | Measures heart function |
ECG waves | Represent different states in the cardiac cycle |
P Wave | Shows atrial depolarization |
QRS sequence | Shows ventricular depolarization |
T Wave | Shows repolarization |
What can an ECG not do? | Measure the ability of the heart to pump blood |
ECG during a physical exam | Typically used for patient's between 35-40 years old and are usually advised to establish a base reading |
Why is it important to know how to read an ECG? | In order to spot urgent problems |
What should be done when an urgent ECG problem is spotted? | Notify the physician ASAP |
Why are size and pattern of ECG graph lines standard? | Any physician can read it |
Calculate heart rate with the QRS sequence | Count the number of QRS sequences in a 6 second span and multiply by 10 |
Calculate heart with the R wave | Count the number of large squares between two R waves and divide by 300 |
Average length of a cardiac cycle | 0.8 seconds |
How does the line get on the ECG tracing paper? | Heat from the stylus melts the coating paper |
Heated stylus | The part of an ECG machine that moves against the tracing paper to record the waves of the ECG cycle |
What should be done if the ECG tracing line is too light? | Increase the stylus heat |
1 large square on an ECG tracing paper | Equal to 25 small squares |
Standard calibration | Up 10 small squares and remain for 2 small squares and then down 10 small squares |
Normal paper speed | 25mm per second |
What do the vertical lines represent on an ECG? | Voltage or the strength of the impulse |
Holder that forms a permanent record of the ECG for the patient's file | Mount |
For what must the tracing paper be cut for before mounting it? | Single channel ECG machine |
Uses a control knob to switch leads | Manual ECG machine |
In a standard ECG how many leads are used? | 12 |
What do ECG leads show? | A view of the heart from different angles |
How did Augmented leads get their name? | The impulses recorded by them must be increased to be read |
Standard leads | The lines between which form Einthoven's triangle
They are also known as bipolar leads and each one monitors two limb electrodes |
Electrodes | Placed on a patients limbs and chest in an ECG to detect impulses |
Right leg limb electrode | Used as a reference point and is not part of the ECG recording |
Limb leads | Monitor electrodes placed on the patients arms and legs |
A 12 lead ECG consists of | 3 Bipolar limb leads - Leads I, II, and III
3 Unipolar limb leads - aVR, aVL, and aVF
6 Unipolar chest leads (also known as Precordial or V leads) - V1, V2, V3, V4, V5, and V6 |
Lead I | Shows the voltage difference between the right arm and the left arm |
Lead II | Shows the voltage difference between the right arm and the left leg |
Lead III | Shows the voltage difference between the left arm and the left leg |
Lead aVR | Shows the voltage difference between the right arm and the midpoint of the left arm and left leg |
Lead aVF | Shows the voltage difference between the left leg and the midpoint of the right arm and left arm |
Lead aVL | Shows the voltage difference between the left arm and the midpoint of the right arm and the left leg |
Precordial leads | Monitor the electrodes placed on the chest and consist of leads V1, V2, V3, V4, V5, and V6 |
At what site does lead V1 monitor an electrode? | 4th intercostal space on the right side of the sternum |
At what site does lead V2 monitor an electrode? | 4th intercostal space on the left side of the sternum |
At what site does lead V3 monitor an electrode? | Midway between V2 and V4 position - this is why V4 should be placed before V3 |
At what site does lead V4 monitor an electrode? | 5th intercostal space on the left mid-clavicular line |
At what site does lead V5 monitor an electrode? | Horizontal to V4 at the left anterior axillary line |
At what site does lead V6 monitor an electrode? | Horizontal to V4 at the left mid axillary line |
ECG artifacts on Lead I and II | Check the right arm electrode |
ECG artifacts on Lead II and III | Check the left leg electrode |
ECG artifacts on Lead I and III | Check the left arm electrode |
Artifact | ECG interference |
What causes AC interference? | Electrical equipment and wires |
What should be done for AC interference? | Make sure power cords are not near the patient |
What causes Somatic tremors? | Muscle movement or shivering |
What can be done for a nervous or tense patient? | Explain the procedure and reassure the patient |
What causes a wandering baseline? | The stylus shifts from the center of the tracing paper |
What causes an interrupted baseline? | Broken or not secured ECG connections |
What should be checked for an interrupted baseline? | The lead wires to make sure they are attached to the electrodes |
Abnormality | Arrhythmia |
Sinus Tachycardia | 100+ beats per minute |
Premature Ventricle Contraction (PVC) | Common disruption in rhythm - Ventricles produce extra hear beats before expected |
Premature Atrial Contractions (PAC) | Atria produce extra heart beats before expected |
Paroxysmal Atrial Tachycardia (PAT) | Regular heart contractions with 160-250 beats per minute |
Without immediate treatment will result in death | Ventricular Fibrillation
The ventricles of the heart can not properly pump blood to the rest of the body |
Ventricular Fibrillation (V-fib) | Rapid irregular fluttering/quivering heart rhythm in the ventricles of the heart |
Which arrhythmia increases the risk of stroke? | Atrial Fibrillation |
Atrial Fibrillation (A-fib) | Rapid irregular quivering/fluttering heart rhythm in the atria of the heart |
What test records the activity of a patients heart for 24+ hours? | Holter Monitor |
How many leads does a Holter monitor have? | Up to 5 leads |
What are some of the assistants jobs during Holter monitoring? | To check the battery, prepare and instruct the patient, and apply and remove the Holter monitor |
What is the purpose of a patient diary during a Holter monitor test? | To supply a link to patient activity at the time of abnormal results |
What does a stress test measure? | A heart's reaction to an increased need for oxygen |
What does the assistant monitor during a stress test? | Blood Pressure |