Introduction to 12 Lead ECGs

Introduction to 12 Lead ECGs : 

Introduction to 12 Lead ECGs EMS Professions Temple College

Topics : 

Topics Why 12 Lead ECGs? Critical Concepts in ACS Monitoring vs Diagnostic ECGs Acquisition & Transmission

Why 12 Lead ECGs? : 

Why 12 Lead ECGs? Demonstrated Advantages Rapid Identification of Infarction/Injury diagnosis made sooner in many cases Decreased Time to Reperfusion Treatment speeds preparation of & time to reperfusion therapies Increased Index of Suspicion Modification to Therapies

Why 12 Lead ECGs? : 

Why 12 Lead ECGs? Perceived Disadvantages Increased time spent on scene demonstrated at 0-4 min increase Cost equipment & training No clinical advantage to patient & “our transport times are short” demonstrated decrease in time to treatment compare to early notification for trauma patients Not helpful in “our system” Possibly true!

Why 12 Lead ECGs? : 

Why 12 Lead ECGs? American Heart Association in collaboration with International Liaison Committee on Resuscitation. Guidelines 2000 for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care: International Consensus on Science, Part 7: The Era of Reperfusion. Circulation. 2000; 102 (suppl I): I-175. “The US National Heart Attack Alert Program recommends that EMS systems provide out-of-hospital 12-lead ECGs to facilitate early identification of AMI and that all advanced lifesaving vehicles be able to transmit a 12-lead ECG to the hospital”

Critical Concepts in ACS : 

Critical Concepts in ACS Ischemia lack of oxygenation ST segment depression or T wave inversion Injury prolonged ischemia ST segment elevation Infarct prolonged injury results in death of tissue may or may not show Q wave

Critical Concepts in ACS : 

Critical Concepts in ACS ST elevation - the key to the acute reperfusion therapy subset You can’t see ST elevation without a 12-lead ECG Perform on every patient suspected of ACS Obtain early Repeat frequently

Critical Concepts in ACSWill Infarct Occur? : 

Critical Concepts in ACSWill Infarct Occur? Tissue Death? Plaque Rupture Thrombus Formation Coronary Vasoconstriction Collateral Circulation Myocardial Oxygen Demand

Critical Concepts in ACS : 

Critical Concepts in ACS Chest pain or anginal equivalent suspicious of ischemia Immediate assessment and initial general treatment Assess initial ECG ST elevation or new BBB ST depression or T inversion Nondiagnostic - no ST-T deviation Prepare and evaluate for reperfusion therapy Fibrinolytics or primary PTCA Our Focus is Here!

Critical Concepts in ACS : 

Critical Concepts in ACS Fibrinolytics Retaplase (rPA) Actiplase (tPA) Streptokinase (rarely used today) Percutaneous Transluminal Coronary Angioplasty (PTCA) Balloon angioplasty Stent placement Atherectomy Acute Reperfusion Therapies

Critical Concepts in ACS : 

Critical Concepts in ACS Pain is Injury Pain-Free is the Goal Time is Muscle Door to Reperfusion Therapy Time is the issue

Monitoring vs Diagnostic ECGs : 

Monitoring vs Diagnostic ECGs Extra wires 3 wires vs 10 wires Are there other differences?

Monitoring vs Diagnostic ECGs : 

Monitoring vs Diagnostic ECGs Monitoring Quality ECG Designed to provide information needed to determine rate and underlying rhythm Designed to “filter out” artifact Reduces the amount and degree of electrical activity seen by the ECG monitor

Monitoring vs Diagnostic ECGs : 

Monitoring vs Diagnostic ECGs Monitor Quality

Monitoring vs Diagnostic ECGs : 

Monitoring vs Diagnostic ECGs Diagnostic Quality ECG Designed to accurately reproduce QRS, ST and T waveforms Designed to look more broadly at the cardiac electrical activity Unfortunately, may result in greater artifact being visible

Monitoring vs Diagnostic ECGs : 

Monitoring vs Diagnostic ECGs Diagnostic Quality

Monitoring vs Diagnostic ECGs : 

Monitoring vs Diagnostic ECGs Frequency Response Term used to describe the breadth of the electrical spectrum viewed by the ECG monitor Diagnostic quality is usually 0.05 Hz to 150 Hz Monitor quality is usually 0.5 Hz to 20-50 Hz Usually printed on the ECG recording strip

Monitoring vs Diagnostic ECGs : 

Monitoring vs Diagnostic ECGs

Acquisition & Transmission : 

Acquisition & Transmission ECG quality begins with skin preparation and electrodes Hair removal Skin preparation Age & Quality of Electrodes & Cables Electrode Placement

Acquisition & Transmission : 

Acquisition & Transmission Hair Removal Clipper over razor Lessens risk of cuts Quicker Disposable blade clippers available Most EMS systems use razors

Acquisition & Transmission : 

Acquisition & Transmission

Acquisition & Transmission : 

Acquisition & Transmission Skin Preparation Helps obtain a strong signal When measured from skin, heart’s electrical signal about 0.0001 - 0.003 volts Skin oils reduce adhesion of electrode and hinder penetration of electrode gel Dead, dried skin cells do not conduct well

Acquisition & Transmission : 

Acquisition & Transmission Rubbing skin with a gauze pad can reduce skin oil and remove some of dead skin cells

Acquisition & Transmission : 

Acquisition & Transmission Other causes of artifact Patient movement Cable movement Vehicle movement Electromagnetic Interference (EMI)

Acquisition & Transmission : 

Acquisition & Transmission Patient Movement Make patient as comfortable as possible Supine preferred Look for subtle movement toe tapping, shivering Look for muscle tension hand grasping rail, head raised to “watch”

Acquisition & Transmission : 

Acquisition & Transmission Cable Movement Enough “slack” in cables to avoid tugging on the electrodes Many cables have clip that can attach to patient’s clothes or bed sheet

Acquisition & Transmission : 

Acquisition & Transmission Vehicle Movement Acquisition in a moving vehicle is NOT recommended May or may not be successful Tips Pull ambulance over for 10-20 seconds during acquisition Acquire ECG while stopped at traffic light

Acquisition & Transmission : 

Acquisition & Transmission Electromagnetic Interference (EMI) Can interfere with electronic equipment 60 cycle interference is a type of EMI Look for nearby cell phones, radios or electrical devices No contact between cables & power cords Turn off or move away from AC devices Use shielded cables; inspect for cracks

Acquisition & Transmission : 

Acquisition & Transmission Things to look for Little or no artifact Steady baseline

Slide 30: 

Acquisition & Transmission

Acquisition & Transmission : 

Acquisition & Transmission ECG Accuracy depends upon Lead placement Frequency response Calibration Paper speed

Limb Lead Placement : 

Limb Lead Placement Traditional Placement Acceptable Placement Avoid placing on the trunk!!!

Chest Lead Placement : 

Chest Lead Placement V1: fourth intercostal space to right of sternum V2: fourth intercostal space to left of sternum V3: directly between leads V2 and V4 V4: fifth intercostal space at left midclavicular line V5: level with V4 at left anterior axillary line V6: level with V5 at left midaxillary line

Chest Lead Placement : 

Chest Lead Placement

ECG Accuracy : 

ECG Accuracy Look for: Negative aVR if aVR upright, look for reversed leads One complete cardiac cycle in each lead Diagnostic frequency response Proper calibration Appropriate speed

ECG Accuracy : 

ECG Accuracy Frequency Response Display screen is non-diagnostic Use the printed ECG for ST segment analysis

ECG Accuracy : 

ECG Accuracy Calibration Voltage measured vertically Each 1 mm box = 0.1 mV 1 mV = 10 mm calibration standard Confirm calibration calibration impulse should be 10 mm (2 big boxes tall) stated calibration should be “x 1.0”

Calibration : 

Calibration

ECG Accuracy : 

ECG Accuracy Paper Speed Standard is 25 mm/sec Faster paper speed means the rhythm will appear slower and the QRS wider Slower paper speed means the rhythm will appear faster and the QRS narrower

Paper Speed : 

Paper Speed Paper Speed

When to Acquire : 

When to Acquire Note times and differences in these two ECGs for the same patient

When to Acquire : 

When to Acquire Assessment Vital Signs Oxygen Saturation IV Access 12-Lead ECG Brief History Treatment Oxygen Aspirin Nitroglycerin Morphine Modified from “The Ischemic Chest Pain Algorithm”, ACLS Textbook, Chapter 9, American Heart Association, 1997.

Exposing the Chest : 

Exposing the Chest Immediately upon suspecting ACS... Remove all clothing above the waist Or, open shirt/blouse Replace with gown (if possible) Allows for complete exam Minimizes wire entanglement Enhances quick defib if VF occurs

Transmission : 

Transmission Transmit as soon as possible Can use patient’s land-line Many EMS systems use cell phone enroute Coordinate with ED Correlate ECG with a specific patient Early notification of AMI is key!!!