ECG &Machine Principles

ECGELEMENTS

+ +

=

ELECTROCARDIOGRAPHER

ECG PAPER

ECG PAPER

ECG LEADS

ECG LEADS

ECG Vectors & Deflections

Frontal plane Horizontal Plane

CARDIAC Axis

Find Most Isoelectric

Find Perpendicular

Because aVL is POSITIVE (upward deflection on the ECG), the axis is approaching aVL, so it’s – 30°. If it was NEGATIVE on the ECG, the axis would be at the tail of the arrow, so 150°.

Is it positive or negative?

This patient’s axis is deviated to the LEFT. (– 30°)

ECGTRACING EXERCISE # 1

WHAT WE NEED TO KNOW…1. PAPER DEFINITIONS2. DOMINANT WAVES3. AMPLITUDE4. DURATION5. WAVE-WAVE RELATION 6. WAVE-LEAD RELATION

ECGTRACING EXERCISE # 2

AHA CONSIDERATIONSPatient & Machine Dependent

1. Lead axis & Heart Vector projection on lead.2. Lead as a vector (direction and length).

Unipolar?3. Strength or signal magnitude variables.4. Impedances.5. Artifact, Filtering & Frequency cut offs.6. Movement, Position, Rib direction,

Imaginary lines, Amputations, Female breasts, Implants and Obesity.

7. PMH. CC. CI.8. Computer Interpretation.

AHA CONSIDERATIONSOperator Dependent

1. Skin cleaning. Retraining.2. 12 Electrode TYPICAL placement. 3 lead?3. Limb leads placement.4. Precordial Placement of leads.5. V4 – V6 horizontal plane.6. V5 between V4 &V6.7. Common placement errors. High, low,

curved, switched.8. Reproducibility?9. Labeling.

ECGCLINICAL UTILITY

ECGUtility Arrhythmias. Acute Coronary Syndromes (ACS). Conduction Disturbances. Hydro – Electrolytic (HE)

Abnormalities. Electrical & Structural Abnormalities.Also: Monitoring Anti-

ArrhythmicTreatment. Non Cardiological Pre-Op Assesment. Screening High Risk Activities. (Work/

sports)

ECG & ARRHYTHMIASInterpretation Method

ARRHYTHMIAClassificationsABNORMALITY

1. Conductiona. AV Blocksb. Bundle Blocks

2. Origina. Supraventricular

- Extrasystoles- Escape Beats- Junction

b. Ventricular- Extrasystoles- Escape Beats

HEART RATE1. Tachyarrhythmia

sa. Regularb. Irregular

2. Bradyarrhythmiasa. Regularb. Irregular

ARRHYTHMIASTACHYCARDIAS

1. ST (r)

2. A. FIB. (i)

3. A. FLU. (r)4. WPW5. TSVP

(r)6. JT

(r)7. MFAT

(i)

8. TV MONOM. (r)

9. TV POLIM. (i)10. TDP (i)11. VF

(i)BRADYCARDIAS

12. SB13. AV BLOCKS

- 1°- 2° MI- 2° MII- 3°

14. HBB BLOCKS15. TC Pacing.

CA RHYTHMS16. VENTRICULAR

FIBRILATION

17. PULSELESS VENTRICULAR TACHYCARDIA

18. PULSELESS ELECTRICAL ACTIVITY

19. ASYSTOLE

ARRHYTHMIAInterpretation Method

1. Identify what’s normal = RHYTHM & AXIS

2. Establish Heart Rate (HR) = FREQUENCY

3. Determine Regularity = PATTERN4. QRS Width = ORIGIN.5. P Morphology = ATRIAL ACTIVITY6. P/ QRS Ratio = AV CONDUCTION

7. ST & T = VENT. REPOLARIZATION

RHYTHM

Definition of Rhythm. Sinus Rhythm Variations of Rhythm. Alterations of Rhythm Long L-II

CARDIAC Axis

HR & PATTERN

ORIGIN QRS COMPLEX Wide VENTRICULAR Narrow SUPRAVENTRICULAR

AURICULAR Activity:P WAVE P WAVE

- Anterograde- Retrograde

AV Conduction: PR INTERVAL

Second – Degree AV Block (2 types)

ECGQT INTERVAL

Useful in Tachyarrhythmiaslike TORSADE DE POINTS (a type of Ventricular Polimorphic Tachycardia)

Torsade de Points

ECGST SEGMENT & T WAVE

More useful in Acute Coronary Syndromes& HE disturbances.