WELCOME TO THE CRAZY WORLD OF ELECTROCARDIOGRAPHY!!!
WELCOME TO THE CRAZY WORLD OF ELECTROCARDIOGRAPHY!!!
SO WHAT DOES ECG MEAN?
An electrocardiogram is a machine used to measure the electrical activity of the human heart It is usually the diagnostic tool of choice in order to investigate cardiac anomalies in most patients The ECG is the most important and definitive noninvasive diagnostic test for cardiac arrhythmias
SO WHAT DOES ECG MEAN?
The ECG printout is generally recorded at a paper speed of 25 mm/sec is universal
In the vertical direction, the amplitude of ECG signals is measured in millivolts; standardization of 1 mV per 10mm is universal
LET’S LOOK DEEPER INTO
YOUR ECG PAPER!
HOW DO YOU READ AN ECG GRID?
Look for the heavy lines on your ECG grid
Between these heavy lines are 5 smaller boxes down and 5 boxes up that form your big boxes
LET’S TAKE A CLOSER LOOK!
LET’S START WITH THE
BASICS
Your heart being one of the most important organs in the body is a complex mechanism of muscles It is divided into 4 chambers 2 in the upper and 2 in the lower The upper chambers receive blood while the lower ones distribute blood In order for these muscles to perform rhythmically it needs to be stimulated electrically in a synchronous manner Any abnormality in the cardiac muscle or in the distribution of these electrical impulses results in problems such as arrhythmias.
CARDIAC CONDUCTION SYSTEM
TWO CELL TYPES OF THE HEART MUSCLE - working cells - conducting cells
CARDIAC PACEMAKER - is the original site where a cardiac impulse may be generated - any cardiac muscle cell is a potential pacemaker
CARDIAC CONDUCTION SYSTEM
SINO ATRIAL NODE - master pacemaker - has an innate firing rate of 80-100 bpm. - located at the junction of the RA and the SVC/IVC
CARDIAC CONDUCTION SYSTEM
SINO ATRIAL NODE - sends an initial ripple impulse down to the right and left auricles - the impulse generated causes the muscles in that particular region to contract
CARDIAC CONDUCTION SYSTEM
SINO ATRIAL NODE - once the impulse travels down both atrias are depolarized which produces the first positive deflection from the isoelectric line in your ECG
CARDIAC CONDUCTION SYSTEM
ATRIO -VENTRICULAR NODE - initial impulse from the SA node is passed down to another nodal pathway - impulse conducted by the AV node from the SA node travels downward causing further depolarization as it is conducted from one cardiac cell to the next - has an innate firing rate of 60-100bpm
CARDIAC CONDUCTION SYSTEM
BUNDLE OF HIS - left bundle branch (anterior and posterior fascicle) depolarizes the left ventricle - right bundle branch depolarizes the right ventricle
CARDIAC CONDUCTION SYSTEM
QRS COMPLEX - original impulse generated from the AV node is now depolarizing the ventricles which in turn causes full contraction of the lower chambers - second positive deflection from the isoelectric line in your ECG
PATHWAY SUMMARY
NOW WHAT DO WE MEAN WHEN WE SAY ECG COMPLEX?
This is 1 ECG complex
Complex is a term used to denote 1 cardiac cycle
Cardiac cycle in simple terms is also equivalent to a single heartbeat
NOW WHAT ARE THE PARTS OF AN ECG COMPLEX?
Isoelectric line P wave PR interval Q segment R segment S segment ST segment T wave U wave
WHAT IS A P WAVE?
Is the 1st visible positive deflection from the isoelectric line Is also equivalent to your atrial depolarization N= .04 - .08 seconds Comprises approx. 1-2 small squares in the ECG grid
WHAT IS A PR INTERVAL?
The isoelectric segment recorded between P and QRS is called the PR segment In reality, the PR interval starts from the beginning of the P wave and ends at the onset of the QRS complex It represents the timeframe used when the electrical impulse is conducted from the atria down to the ventricles N= .12 - .20 seconds Comprises approx. 3-5 small squares in the ECG grid
WHAT IS A QRS COMPLEX?
Is the 2nd visible upward deflection from the isoelectric line Is also equivalent to your ventricular depolarization N= .04 - .08 seconds Comprises approx. 1-2 small squares in the ECG grid
WHAT IS A T WAVE?
Is the 1st positive deflection after the QRS complex
Is also equivalent to your ventricular repolarization
N=
Comprises approx.
ECG COMPONENTS SUMMARY
P WAVE
PR INTERVAL
QRS COMPLEX
ST SEGMENT
T WAVE
U WAVE
BEFORE ANYTHING ELSE!
ARTIFACTS -
caused by electrical interference metal objects ground hum muscle tremors
UTILIZE A SYSTEMATIC APPROACH!!!
THE SIX STEP METHOD 1.Make sure that you have a six second strip 2.Learn how to determine the rhythm 3.Learn how to get the rate 4.Check for all the parts 5.Find out the relationship of each of the parts 6.Make your interpretation
HOW DO YOU GET A SIX SECOND STRIP?
Look above your ECG paper You will notice that there are heavy markings on top of the strip, these are called time markings The markings will either be in 3/6 second intervals depending on the maker or brand of the ECG tape
THE SIX SECOND STRIP
In between two heavy markings is a 3 second strip
So obviously we need 3 time markings to get our needed 6 second strip
HOW DO YOU DETERMINE THE RHYTHM?
There are only 2 things to know, is it regular or irregular
Look for the R waves in your 6 second strip
Check for the intervals of all the R waves in the strip
If they’re the same then its regular, if not then its irregular
LET’S PRACTICE SHALL WE?
Check for the R-R intervals, measure if they’re ALL equal in the 6 second strip You can also use P-P intervals
LET’S DO IT TOGETHER OK!
Ok, measure the R-R intervals in all complexes Are they ALL equal in duration? What’s the rhythm? Did you get it? REGULAR! Very good! Give the person on your right a congratulations if he got it right!
OK TRY ANOTHER ONE!
Ok check all the complexes in the strip Measure the R-R intervals between each complex Well are they ALL the same? So what’s the rhythm? Regular or irregular? Well its IRREGULAR this time, very good your getting it! Give the person in front of you a high five if he got it right!
NOW ALTOGETHER AGAIN
Ok check out this one You know what to do What do you look for So what can you say this time Yup its IRREGULAR! Well done! Now pat the back of the guy on your left if he got it!
NOW LETS MOVE TO STEP 3 Determining the heart rate of the strip. You can do either a VENTRICULAR rate or an ATRIAL rate whichever you like Ventricular rate uses the R-R intervals Atrial rate uses the P-P intervals Go back to RHYTHM determination to know which method to use in getting the RATE.
WHEN I CHECK FOR THE RATE, WHAT METHOD DO I USE?
MEMORY METHOD - ideal for regular rhythms
DIVISION METHOD - ideal for regular rhythms
MULTIPLICATION METHOD - ideal for irregular rhythms
THE MEMORY METHOD
Also known as the 300, 150, 100 method Utilizes the big box grids and assigns each box a set numeric value
NOW HOW DO WE APPLY THE MEMORY METHOD?
Look for an R wave that falls on a heavy line
Assign each big box a value in the 300, 150, 100 series
Approximate the value based on the distance of the R wave on the next heavy line
NOW YOU TRY IT!
THE DIVISION METHOD
Using the BIG BOXES use the constant 300 as your divisor, and count the total number of big boxes consumed within 1 set R-R intervals Using the SMALL BOXES use the constant 1500 as your divisor, and count the total number of small boxes consumed within 1 set R-R intervals
NOW LET’S APPLY THE
DIVISION METHOD!
Ok start by the same way we did before, look for an R wave that falls on a heavy line Count the number of big and small boxes from the R wave you chose until the next R wave. 300/ TOTAL # of BIG BOXES or 1500/ TOTAL # of SMALL BOXES = APPROXIMATE HEART RATE
NOW ITS YOUR TURN!
THE MULTIPLICATION METHOD
Ok! Its time for me to hide! WHY??? This is probably the fastest and easiest way to get your heart rate since it can be used for both regular and irregular rhythms Count all the R waves you can find in a 6 second strip multiply it by ten to get the heart rate
OK IT’S TIME TO PRACTICE!
NOW LETS MOVE TO STEP 4 CHECK FOR ALL THE PARTS
Know all the parts of your ECG complex
Check all the P waves, QRS complexes, PR intervals, etc.
Are they all present?
Are they normal in morphology?
Do they have normal durations?
STEP 5 COMPARING RELATIONSHIPS
Is there a P for every QRS complex? Are they all upright and normal in appearance? Do they all look the same with all the other complexes? Check for the pacemaker origin (SA, atrial, junctional, ventricular, multi focal) Check for patterns in changes, regularity or irregularity in the appearance and duration of certain waveforms
AND THE FINAL STEP MAKE YOUR INTERPRETATION!
Try to get the entire picture based on all the bits of information that you gathered Piece In together all your observations from the rates, rhythm, P wave, QRS complexes, etc Based on all these you can now make your conclusion on what type of ECG rhythm you have In simple terms its your intelligent guess
POSSIBLE RHYTHMS YOU MAY ENCOUNTER IN LEAD II
ATRIAL RHYTHMS - normal sinus rhythm - sinus tachycardia - sinus bradycardia - sinus arrhythmia - wandering pacemaker - atrial flutter - atrial fibrillation HEART BLOCKS - 1ST degree - 2nd degree (type I and type II) - 3rd degree
ATRIO-VENTRICULAR RHYTHMS - supraventricular tachycardia - junctional escape - accelerated junctional VENTRICULAR RHYTHMS - PVC’s - ventricular tachycardia - ventricular fibrillation DEAD RHYTHMS - PEA’s/ EMD’s - agonal - asystole
??????? HE HE HE DID YOU GET ALL OF THEM
POSSIBLE RHYTHMS YOU MAY ENCOUNTER IN LEAD II
ATRIAL RHYTHMS - normal sinus rhythm - sinus tachycardia - sinus bradycardia - sinus arrhythmia - wandering pacemaker - atrial flutter - atrial fibrillation HEART BLOCKS - 1ST degree - 2nd degree (type I and type II) - 3rd degree
ATRIO-VENTRICULAR RHYTHMS - supraventricular tachycardia - junctional escape - accelerated junctional VENTRICULAR RHYTHMS - PVC’s - ventricular tachycardia - ventricular fibrillation DEAD RHYTHMS - PEA’s/ EMD’s - agonal - asystole
ATRIAL RHYTHMS
NORMAL SINUS RHYTHM - all ECG complex components are present - morphology and duration of all components are normal - with a regular HR within 60-100 bpm
ATRIAL RHYTHMS
SINUS TACHYCARDIA - all ECG complex components are present - morphology of all components are normal - with a regular HR>100 bpm
ATRIAL RHYTHMS
SINUS BRADYCARDIA - all ECG complex components are present - morphology of all components are normal - with a regular HR<60 bpm
ATRIAL RHYTHMS
SINUS ARRYTHMIA - all ECG complex components are present - morphology and duration of all components are normal - with an irregular HR maybe fast or slow
ATRIAL RHYTHMS
WANDERING ATRIAL PACEMAKER - all ECG complex components are present - characteristic varying P wave morphology - each abnormal P has a conducted QRS complex 1:1 RATIO - regular rate - pacemaker origin usually between the SA node and AV junction
ATRIAL RHYTHMS
ATRIAL FLUTTER f WAVES - irritable ectopic unifocal atrial focus - rapid atrial rate - characteristic “saw tooth pattern”
ATRIAL RHYTHMS
ATRIAL FIBRILLATION F WAVES - chaotic firing of multiple atrial ectopic foci - ventricles are able to catch some of the impulses being fired by the atria resulting in conducted QRS complexes - irregular ventricular rate
ATRIO-VENTRICULAR RHYTHMS
JUNCTIONAL ESCAPE - characteristic inversion or absence of the P waves prior to their respective QRS complexes - usually controlled and with a HR 40-60 bpm
ATRIO-VENTRICULAR RHYTHMS
ACCELERATED JUNCTIONAL ESCAPE - characteristic inversion or absence of the P waves prior to their respective QRS complexes - usually uncontrolled and with a HR 60-100 bpm
ATRIO-VENTRICULAR RHYTHMS- HEART BLOCKS
1ST DEGREE HEART BLOCK - constant prolongation of the PR interval - no dropped QRS complexes
ATRIO-VENTRICULAR RHYTHMS- HEART BLOCKS
2ND DEGREE HEART BLOCK TYPE I MOBITZ I
WENKEBACH PHENOMENON - gradual prolongation of the PR interval followed by a dropped QRS complex - a P wave not partnered with a QRS complex
ATRIO-VENTRICULAR RHYTHMS
2ND DEGREE HEART BLOCK TYPE II MOBITZ II - PR interval may either be constantly or gradually prolonged and it results in dropped QRS complexes - usually occurs below the AV node at the bundle branches
ATRIO-VENTRICULAR RHYTHMS- HEART BLOCKS
3RD DEGREE HEART BLOCK COMPLETE HEART BLOCK - total absence of communication between the atria and the ventricles - atrial firing is independent from the ventricular firing
VENTRICULAR RHYTHMS
VENTRICULAR TACHYCARDIA - regular wide QRS complexes in tachy form - check if pulse less or with pulse - can easily progress to VFIB
VENTRICULAR RHYTHMS
TORSADES DE POINTES -
form of VTAC but with characteristic varying amplitude
-
regular rate but pacemaker may vary at times
VENTRICULAR RHYTHMS
PREMATURE VENTRICULAR CONTRACTIONS
NATURE
FREQUENCY/ OCCURANCE
- unifocal
- bigeminy
- multi focal
- trigeminy
- quadrigeminy
VENTRICULAR RHYTHMS
VENTRICULAR FIBRILATION - abnormal chaotic ventricular activity - multiple ectopic ventricular foci impulse firing - also termed as “quivering heart”
DEAD RHYTHMS
PULSELESS ELECTRICAL ACTIVITY (PEA)
ELECTROMECHANICAL DISSOCIATION (EMD)
DEAD RHYTHMS
AGONAL
DEAD RHYTHMS
ASYSTOLE - total absence of electrical activity in the heart - cardiac standstill
PRACTICE!!!
PRACTICE!!!
PRACTICE!!!
PRACTICE!!!
PRACTICE!!!
PRACTICE!!!
PRACTICE!!!
PRACTICE!!!
FINAL WORDS
Every strip is always subject to different interpretations depending on how and who is looking at it No matter what the strip is saying, always stop, look, and listen first to your patient, talk to them before doing anything. Treat your patient not your monitor By the time you go to the toilet in the morning, all that you’ve learned will all go down the drain when you flush!!! SO PLEASE CONTINUE TO PRACTICE!
