1. Chapter 37
Electrocardiography

2. Anatomy of the Heart Four chambers Deoxygenated blood Oxygenated blood
Two upper chambers known as atria
Two lower chambers known as ventricles
Deoxygenated blood
Oxygenated blood

3. Anatomy of the Heart
Coronary arteries
Watch the animation

4. Electrical Conduction System of the Heart
Sinoatrial (SA) node
Atrioventricular (AV) node
Bundle of His and Purkinje fibers

5. Electrical Conduction System of the Heart
Systole and diastole
Impulses can be recorded on ECG paper or displayed on oscilloscope

6. The Cardiac Cycle and the ECG Cycle
Baseline or isoelectric line
Positive deflection
Negative deflection
Each cardiac cycle takes about 0.8 second

7. The Cardiac Cycle and the ECG Cycle
P, QRS, and T waves

8. Calculation of Heart Rate
On ECG graph paper:
Every fifth line is darker than other lines
Time is measured on horizontal line
Voltage is measured on the vertical line

9. Types of Electrocardiographs
Single-channel ECG >>
Multichannel ECG
Automatic ECG machines
(see Procedure 37-1 in the text)

10. Types of Electrocardiographs
ECG telephone transmissions
Facsimile electrocardiograph
Interpretive electrocardiograph

11. ECG Equipment Electrocardiograph paper Black or dark blue
Wax or plastic coated
Heat and pressure sensitive
Heat of stylus can be adjusted to obtain a sharp tracing

12. ECG Equipment Electrolyte
Help pick up electrical current produced by contraction and relaxation of heart
In form of gel, lotion, paste, or pre-saturated pads

13. ECG Equipment Sensors or electrodes Disposable sensors
Detect electrical impulses on body surface from the myocardium and relay them through cables

14. ECG Equipment Lead wires Caring for equipment
Once self-adhesive sensors are placed, lead wires from the ECG machine are attached
Caring for equipment

15. Lead Coding 12 leads recorded using 10 lead wires
Necessary for identification and mounting purposes
Newer ECGs automatically mark (code) each lead

16. The Electrocardiograph and Lead Placement
12 leads record heart’s electrical activity
Allows for 3D interpretation of activity
Amplification of electrical activity

17. The Electrocardiograph and Lead Placement
Galvanometer changes voltage into mechanical motion
Stylus records motion

18. The Electrocardiograph and Lead Placement
Types of leads
Standard limb or bipolar leads
Augmented leads
Chest leads, precordial leads, or V leads
Placement of electrodes

19. Standardization of the Electrocardiograph
Value of recording depends on accuracy
Universal measurements
One millivolt of cardiac electrical activity will deflect stylus exactly 10 mm high
(discuss the Critical Thinking Box)

20. Standard Resting Electrocardiography
Performing 12-lead electrocardiogram
(see Procedure 37-1 in the text)

21. Standard Resting Electrocardiography
Watch the video
(see Procedure 37-1 in the text)

22. Mounting the ECG Tracing
Commercially prepared mounting forms
Mount completed tracing after provider has reviewed entire recording
Identify patient, date, age, blood pressure, height and weight, and cardiac medications
(see Procedure 37-1 in the text)

23. Interference or Artifacts
Somatic tremor artifacts
Alternating current (AC) interference
Wandering baseline artifacts
Interrupted baseline artifacts
(discuss the Critical Thinking Box)

24. Cardiac Conditions and Diseases
Myocardial infarctions (heart attack)
Primary cause of death in U.S.
Offer patient health tips as part of patient education
Behaviors to adopt for a healthy heart

25. Cardiac Arrhythmias
Watch the video

26. Cardiac Arrhythmias Atrial arrhythmias
Premature atrial contractions (PAC)
Paroxysmal atrial tachycardia (PAT)
Atrial fibrillation

27. Cardiac Arrhythmias Ventricular arrhythmias
Premature ventricular contractions (PVCs)
Ventricular tachycardia
Ventricular fibrillation

28. Defibrillation
Electrical device that applies countershocks to heart through electrodes or pads placed on chest wall (AED)
Can convert cardiac arrhythmia into normal sinus rhythm

29. Holter Monitor Portable ambulatory electrocardiograph
Portable continuous recording of cardiac activity for a 24-hour period
Noninvasive test
Helps diagnose cardiac arrhythmias by correlating them with patient’s symptoms
(see Procedure 37-2 in the text)

30. Holter Monitor Medical assistant’s role Preparing patient
Instructing patient
Applying and removing monitor
(discuss the Critical Thinking Box)

31. Holter Monitor Patient activity diary
Record all activities, emotional states, and time of their occurrence
Record chest pain and other symptoms and time of their occurrence

32. Holter Monitor Removing the Holter Monitor Patient returns to office
Tape is analyzed by scanner or computer
Written report sent to physician

33. Other Diagnostic Tests
Treadmill stress test
Diagnose heart disorders and probable cause of patient’s chest pain
Assess patient’s cardiac ability following cardiac surgery
Noninvasive test
Patient exercises on treadmill at varying rates of speed

34. Other Diagnostic Tests
Loop ECG
Thallium stress test
Echocardiography/ultrasonography

35. Cardiac Procedures Coronary angioplasty with and without stent
Balloon inflated inside coronary artery with or without stent
Keeps artery open
Coronary artery atherectomy
Cutting away of plaque in blocked coronary artery

36. Other Cardiac Diagnostic Tests
Coronary artery bypass
Vein transplanted into blocked coronary artery(ies)
Blood supply reestablished to myocardium
Cardiac computerized tomography and cardiac magnetic resonance