ECG Lead System

Method for ECG Strip reading

1. Atrial and Ventricular Rhythm 2. Atrial and Ventricular rates 3. P-Waves 4. Intervals 5. QRS Complexes 6. ST Segment 7. T-Wave

Where should you put electrodes ?

1. Close to bone 2. Over soft tissue

Other Factors that affect QT interval

1. Ischemia 2. Hypothermia 3. Bradycardia 4. Neurological Imbalance 5. Electrolyte imbalances 6. Recent CVA

Antibiotics

1. Macrolides 2. Erthromycin and Biaxin 3. Fluoroquinolones

Where should you NOT put electrodes

1. Thick muscles 2. Skin Folds 3. Bony prominence's they can cause ECG artifacts that take away from the reading

Antidepressants

1. Tricyclics 2. Haldol 3. HIV protease inhibitors

Identify the three (3) statements that correlate with cardiac cells. A. The heart has pacer cells and myocardial cells. B. Myocardial cells generate and conduct electrical impulses. C. Myocardial cells receive the impulse and do the work. D. Pacer cells are part of the electrical conduction system.

ACD

When the parasympathetic nerve fibers are stimulated, what is released?

Acetylcholine

Six-Second Rule

All Rhythm Types -6 second strip -Total number of R (ventricular) wave or P waves (atrial rate) - x by 10 to find BPM

P-Wave

Atrial Depolarization in response to SA node triggering Atria are stimulated and contract, they push blood through tricuspid and mitral valve into the relaxed ventricles height: 2-3mm duration: 0.06-0.12 seconds

The ECG stylus produces an isoelectric line in response to what?

Balanced electrical force field

ST Segment

Beginning of ventricle repolarization, should be flat Total ventricular activity: complete time for ventricles to depolarize and repolarize duration is most critical: 0.36 to 0.44 seconds (half the distance between R-waves) duration varies with: HR, age, sex male: .39-.41 female: .36-.44

Knoched R Wave

Bundle branch block

Why is the QRS larger than the P wave?

C. Ventricular depolarization involves greater muscle mass than atrial depolarization.

What electrolyte is important in cardiac muscle contraction?

Calcium is much needed for muscle contraction

What if P-waves are absent?

Can indicate that the rhythm was generated somewhere beside the sinus node. Maybe the AV junction

Along with Lead II, lead III is most helpful in monitoring changes in what part of the heart?

Changes associated with inferior wall myocardial infarction

What allows the cardiac cells to transmit an electrical impulse?

Conductivity

PR Interval

Delay of AV node to allow filling of ventricle Atrial-ventricular conduction time. Path of electrical impulse through the AV node, bundle of HIS, right and left bundle branches, to the purkinje fibers PRI is measured from begnning of P wave to start of QRS Duration:0.12-.20 seconds

What does the P wave represent?

Depolarization of both right and left atria

QRS

Depolarization of ventricles, triggers , main pumping contractions represents ventricular depolarization, when ventricles contract, forcing blood out into the arteries Q- depolarization of interventricular septum R and S = depolarization of left and right ventricles duration: 0.04-0.10 seconds

ST segment

Early repolarization of right and left ventricles QRS and ST meet is j point should be flat at isoelectric line: Myocardial injury like acute ischemia

The ECG produces an upright pattern on the paper in response to what?

Electricity flowing from the heart towards a positive electrode

T or F? The QRS is smaller than the P wave.

F

What are ECG artifacts?

False cardiac waveforms

Shorter QT interval

Fast heart rate (heart doesnt have enough time to regroup)

Sequential Method

For regular rhythms only -Select P and R Waves that fall on dark line on ECG Strip -Mark next 6 consecutive dark lines with 300, 150, 100, 75, 60, 50 -If R and P Wave fall on line 100 then HR is 100 BPM

ECG Strips

Has a grid formed by vertical and horizontal lines -Vertical Lines: Waves Amp/Voltage, can be +/- -Horizontal Lines: time, 25mm/second every box = 0.04 seconds 5x5 = 1 square 1 second of time = 5 squares

Myocardial Infraction (MI)

Heart Attack -Have abnormal rhythms. -Death of cardiac muscle due to ischemia

When the sympathetic nerve fibers are stimulated, what is elevated?

Heart rate

What lead would be most helpful to assess bundle branch defects and confirm pacemaker wire placement?

Modified Chest Lead 1 (MCL1)

Inverted T-wave

Myocardial Ischemia

P-Wave disinformation

Notched, peaked or inverted: atrial enlargement associated with COPD, pulmonary emboli, valvular disease or CHF

The electrocardiogram (ECG) complex represents the electrical events occurring in _____.

One cardiac cycle

Doe the ECG machine monitor or control the hearts rhythm?

Only monitors

Cardiac cycle: ECG

P wave: atrial contraction QRS: ventricular contraction T: resting state

Sinus Rythum

P- atrial depolarization QRS-ventricular depolarization (.04-.10) PR Interval- atrial-ventricular conduction time (.12-.20 seconds) QT Interval- ventricular depolarization and repolarization ST Segment- isoeletric should be flat T-Wave- ventricular re-polarization

Which part of the waveform represents atrial depolarization?

P-wave

V1 shows

P-wave QRS complex ST segment

What interval measurement represents the complete refractory period?

PR Interval

Which part of the waveform represents atrioventricular conduction?

PR Interval

T or F? A waveform is movement away from the baseline in either positive or negative direction.

T

T or F? ECGs are used to monitor the effects of new medications.

T

T or F? The QRS complex in the modified chest lead 1 (MCL1) can be negative and still be normal.

T

T or F? To assure good contact, new electrode patches should be applied every 24 hours or whenever a patient bathes, or becomes clammy or sweaty.

T

T or F?The ECG monitor displays the conduction of the electrical impulses through the heart, NOT the actual contraction of the heart muscle.

T

In which part of the waveform does ventricular repolarization occur?

T wave

ECG Pattern

Upward Pattern: electricity flowing from the heart to the electrodes moving to the positive electrode Downward Pattern: electricity flowing from the heart to the electrodes moving away from the positive electrode

What affects preload?

Volume of blood in ventricles

12-Lead Testing System

Whole picture of heart 6 are chest 6 are limb

LL

aVF left leg: positive deflection positive deflection because the hearts electrical activity moves toward the lead

LA

aVL Left arm: positive deflection because the hearts electrical activity moves toward the lead

RA

aVR Right arm: negative deflection because the hearts electrical activity moves away from the lead

A Leads

aVR aVL aVF

How often should electrode location sites on inpatients be rotated? A. 2 hours B. 12 hours C. 24 hours D. 48 hours

every 24 hours

Lead 111

left arm (-) left leg (+) -also positive deflection -also detects changes associated with an inferior wall myocardial infraction

V4

placed at 5th intercostal space and midclavicular line

Leads

recordings of heart activity from several angles around the heart (like adjusting the view for your camera)

Lead 11

right arm (-) to below the last left palpable rib, below the midclavicular line(+) -primary lead -also positive deflection -current travels down and to the left following normal condition system of the heart -info about inferior portion of the heart -useful for detecting sinus node (SA) and atrial arrhythmias

Lead 1

right arm (-) to left arm (+) -positive deflection of ECG tracings -helpful in monitoring atrial rhythms and hemi blocks

Of the following locations, what is the best area to position electrodes?

soft tissue

T-wave

ventricular repolarization amplitude: 0.5mm leads 1,2,3

What interval represents total ventricular activity?

QT Interval

Which segment represents total ventricular activity?

QT Interval

QT correction formula

QTc= QT/ sqrt R-R

What is the first step in preparation of the patient for ECG monitoring?

Reassure patient and maintain privacy

Ectopic P waves may be upright or inverted and originate from somewhere other than the

SA Node

In which segment/interval does early repolarization of R/L ventricles occur?

ST Segment

R-R Interval

Same = Ventricular rhythm regular different = Ventricular rhythm irregular

P-P Interval

Same = atrial rhythm regular different = atrial rhythm irregular

Electrocardiogram (ECG)

Since you can't see the heart beating we use a ECG to provide a picture that replicates the actual cardiac issue.

Longer QT interval

Slower heart rate (heart is working to hard

V1

-corresponds to modified chest lead (MCL1) placed Right side of sternum, 4th intrcostal space -Distinguishes between right and left ventricular topic beats

What is the normal measurement for the QRS complex?

0.04 to 0.10 seconds

A PRI is considered short if it is less than ___ second and long if it is more than ___ second

0.12, 0.20

Atrial/Ventricular Rate 1500 Rule

-2 consecutive rates for P (atrial) rate -2 consecutive rates for R (Vent) rate -Count # of small boxes between them -Divide 1500 by total # of boxes

Atrial/Ventricular Rate 300 Rule

-2 consecutive rates for P (atrial) rate -2 consecutive rates for R (Vent) rate -Count # of sqaures between them -Divide 300 by this #

Caliper Measure for Atrial

-Lay strip flat on desk -Position Left caliper leg on 1st P wave and Right on second peak (P-P Interval) -turn caliper to next P wave, and continue down to make sure P-P wave line up

Caliper Measure for Atrial

-Lay strip flat on desk -Position Left caliper leg on 1st R wave and Right on second R peak (R-R Interval) -turn caliper to next R wave, and continue down to make sure R-R wave line up

V1 monitors:

-Ventricular arrhythmia -ST segment changes -Bundle branch blocks

antiarrhythmics

1. Amiodarone 2. Tikosyn 3. Pronestyl 4. Quinidine 5. Sotalol

Lead I is helpful for monitoring?

Hemi blocks

QRS > 0.10 seconds means

Intraventricular conduction delay

Straight line when machine is turned on but not connected to the patient

Isoelectric = no current It is straight because there is a balanced electrical force field. This Isoelectric line acts as a starting point for the patterns to be displayed

What do you look at for Inferior MI?

Lead 11

Which lead is helpful in monitoring atrial rhythms and hemiblocks?

Lead I

Which of the following leads would you use to monitor atrial rhythms and hemi blocks?

Lead I

Which lead is the most useful for routine monitoring and monitoring the sinus node?

Lead II

Which of the following leads would be helpful for detecting sinus node and atrial arrhythmias?

Lead II

Biphasic

Lead V1-3 with both positive and negative deflections

Modified Chest Lead (MCL1)

Left upper chest (-) to Right Side of the sternum @ 4th inter coastal space (+) and Ground on the right upper chest -Looks at the anterior wall of the heart -can be uses to access QRS complex arrhythmia -premature ventricular and supra ventricular beats -ventricular tachy -bundle branch defects -P-wave changes -Confirm pacemaker wire placement

What is the most common reason for the alarm to sound during an ECG procedure?

Loosening of a leadwire

What do you look at for Anterior MI?

MCL1 test lead

Deep, wide Q wave

MI

Which of the following cells are responsible for spontaneous generation and conduction of electrical impulses?

Pacer Cells

V5

Place at 5th intercostal space and anterior axillaryline positive deflection of ECG

V3

Placed between 2 and 4

V2

Placed left of sternum, 4th intercostal rib space

V6

Placed level with v4 and midaxillary line positive deflection

Tall P-Wave

Potassium abnormality

What is an important electrolyte that affects cardiac function?

Potassium and Calcium

What factors impact afterload? (select all that apply) A. Arterial contractility B. Pressure C. Resistance D. Volume

Pressure Resistance

Which part of the waveform represents ventricular depolarization?

QRS Complex