INTRODUCTION TO EKGs STUDY GUIDE

This class is a basic introduction to EKG interpretation in order that you can make a satisfactory test score for your Annual Skills Competency Training. It touches on basic heart anatomy, circulation, conduction, and nervous system controls. This program will define EKG and review EKG lead placement. This program will review basic rhythms, and provide an overview of critical dysrhythmias and their causes. The course will also discuss possible sources of interference and common artifact issues.

Objectives

1. Review the location, anatomy, and blood flow of the heart. 2. Explain the heart’s conduction system and discuss the effect of the nervous

system . 3. Review EKG lead placement and basics. 4. Identify basic cardiac rhythms; critical dysrhythmias and their causes. 5. Review Standing Delagated Orders that are pertinent to emergency cardiac care. 6. Discuss the effect of artifact and EMI (electro-magnetic interference) on EKG

interpretation. The Location of the Heart The heart is a cone shaped structure the size of your fist. The heart is located in a lubricated sac (the pericardium) in the left center of the thorax (chest). The heart is protected by the breastbone in the front, the spinal cord in the back and the lungs on both sides.

Cardiac Anatomy Basic Description The heart has two upper chambers called the “Atria” and two lower chambers called the “Ventricles”. The right Atrium is larger than the left Atrium but has thinner walls. The chamber of the left Ventricle has walls that are three times the thickness of the right Ventricle. This is important because the oxygenated blood that it receives from the left Atrium has to be pumped throughout the body.

The Septum is a partition that separates the right and left sides of the Heart. The upper part of the Septum should be closed all the time but sometimes an opening is present at birth. This would be considered a, “Congenital Heart Defect”.

The Location of the Heart Valves The location of these four valves are:

1. Tricuspid (3-leaf valve) valve between right atrium & ventricle

2. Mitral or Bicuspid (2 leaf valve) valve located between left atrium & ventricle

3. Pulmonic valve located between the right ventricle & pulmonary artery 4. Aortic valve located between the left ventricle & the aorta

Valves are strong, thin, leaflets of fibrous tissue covered by cells. They allow the blood to pass only in one direction. They function like a gate which opens only when pushed. The valves open and close in response to the naturally occurring pressure that builds up within the heart's chambers. When you are listening to the heart beat with a stethoscope, the “lub-dub” sound you hear are the closing of these valves (S1 & S2).

Below is a picture of the valves from another angle. Again, note that the Bicuspid valve is the same as the Mitral valve.

Many patients, need to replace their faulty heart valves (ie. Mitral Valve Replacement – MVR for damage done during rheumatic fever). These valves can be replaced with mechanical or animal parts (pig).

There are five areas to listen for the heart valves. To hear the aortic valve, you need to listen over the right 2nd intercostal space close to the sternal border. The pulmonic valve is heard over the left 2nd intercostal space close to the sternal border. The mitral valve is heard at the 5th intercostal space, left of the sternal border, in the midclavicular line. Finally, the triscupid is heard at around the 3rd & 4th intercostal space at the left of the sternal border, and is between the pulmonic and mitral mitral valve sounds. See the picture below for the areas.

When you palpate or place your hands over these valve areas, “thrills” may be felt. These are vibrations transmitted through the skin and caused by turbulent blood flow through the valves. Thrills are sometimes described as feeling “like a cat purring.”

We will now discuss the blood flow of the heart. Use the simple diagram below to trace the flow of blood of the heart.

The right side of the heart is responsible for pulmonary circulation. “Used” blood from your body returns to the right side of the heart via the two large veins- the superior vena cava and the inferior vena cava. These veins deliver the blood to the right atrium where it flows thru the tricuspid valve into the right ventricle. The right ventricle pumps the blood thru the pulmonic valve to the pulmonary arteries. This deoxygenated blood is pumped into the lungs where it releases carbon dioxide and picks up oxygen. The carbon dioxide is expelled into the air by breathing.

Blood rich in oxygen travels to the left side of the heart thru the pulmonary veins and returns back to the heart via the left atrium. The blood then flows thru the mitral valve to the left ventricle from where it is pumped to the rest of the body through the aorta. The Aorta is the largest blood vessel in the body. The inner diameter of the Aorta is about 1 inch.

The aorta descends through the lower part of the thorax and abdomen, where arteries branch off carrying blood to the liver, spleen, intestine, kidneys, gonads, and legs. While the blood circulates throughout the body, substances other than oxygen and carbon dioxide are also transported. The blood carries hormones to their sites of activity. Waste

products are taken to the kidneys and liver. Nutrients are picked up from the intestines and taken to other parts of the body where they are needed.

Also branching off the aorta as it leaves the heart is a pair of coronary arteries. These arteries supply blood to the heart and are considered part of the systemic circulation. After passing through capillaries in the heart, blood in the coronary circuit returns to the right side of the heart through veins that empty directly into the right atrium. Heart attacks are caused by clots in coronary arteries, depriving the heart muscle of oxygen.

Nervous System Controls The Autonomic Nervous System controls the heart action. It consists of both the Sympathetic (SNS) & Parasympathetic Nervous System (PNS). The SNS is known as the “fight or flight system”. It supplies both atria and ventricles. Once stimulated it Increases heart rate, excitability, rate of conduction, and force of contraction

The effects of the PNS are opposite of the SNS. It is known as the “Rest & Digest or Vegetative” system. The PNS affects the vagus nerve which supplies the atrial muscle fibers, and the SA, & AV nodes which are in the upper chambers of the heart. When stimulated, it will decrease the heart rate and rate of impulse. It has little effect on the ventricles.

The Cardiac Conduction System The following parts of the heart play a major roll in stimulating the heart muscle to contract:

SA Node (Sinoatrial)

AV Node (Atrioventricular)

Bundle of HIS

Left & right bundle branches

Purkinje fibers

How Your Heart Contracts - Explains Systole & Diastole Pacemaker cells in the SA node initiate the cardiac cycle. Systole begins when excitation spreads over both atria, activating atrial contraction. Excitation spreads to the AV node, from which excitation is conducted by the bundle of His and the Purkinje system (groups of specialized muscle cells) to the bottom of the ventricles. Excitation spreads upward in the ventricles, contracting them from the bottom up, like squeezing a toothpaste tube from the bottom. When the action potentials end (electrical charges are

changed), diastole (relaxation) begins. The cycle repeats itself. Let’s learn more about these electrical charges.

Cardiac Conduction System Electrocardiogram (EKG) The EKG is a recording of the electrical activity produced by the heart.

Measurement of the electrical activity of the heart is known as an electrocardiogram. Contraction of heart muscle cells is caused by the movement of ions (electrically charged particles or atoms) into and out of the muscle cells. This movement of ions is an electric current that can be observed by placing electrodes on the skin. This electrical current can be measured and recorded on EKG paper by attaching leads to various parts of the body. This is how we are able to measure and record the electrical current tracings.

Cardiac Conduction System: Electrical Activity The heart has three electrical stages where ions move in and out of cells that causes the EKG tracings.

During the Polarization or the Resting Potential phase, there is a negative charge inside the cardiac cell and a positive charge outside the cell. The inside of relaxed muscle cells are negatively charged and are high in Potassium (K+) molecules. Sodium (Na+) molecules are high outside the cell.

During the Depolarization or Action Potential phase, there is a switch in ions and charges. K+ leaves the cardiac cells and Na+ enters the cell. When channels open up, sodium rushes into heart muscle cells, making the inside more positive. This causes calcium channels to open, and calcium rushes in. Calcium causes contractile proteins (actin and myosin) to attach and pull on one another, producing force. Calcium is the most important ion for activating contraction. Potassium going out of the cell makes the muscle cell negative again and terminates the contraction.

This cycle of electrical activity, going from negative to positive to negative again, is called an action potential.

The last phase is called, “Repolarization” or the “Recovery State”. Here the cells return back to their original resting state. Note: that the heart can’t be stimulated until this equilibrium is returned.

Relationship of the EKG tracings to the Electrical Events in the Heart The P wave is the first wave that you will normally see when you are looking at an EKG. It represents atrial depolarization. The next 3 waves, Q, R, & S form the “QRS complex”. This signifies ventricular depolarization. The T wave is the last wave and represents ventricular repolarization. This is the period where the heart is resetting for the next cycle.

The EKG waves and complexes are described as: o PR Interval - time it takes impulse to travel from the SA node to AV node o Ectopic beats - originate outside the SA node o SA node: the “normal pacemaker” 60-100 b/m o AV junction 40-60 b/m

o Ventricular Pacemaker 15-40 b/m

The heart is a unique organ in that any cell is capable of initiating an electrical impulse or heart beat. Any impulse that originates outside the SA node is called an “ectopic beat”.

Electrocardiogram (EKG) All UTMB/CMC EKGs are 12 lead. Every unit has a 12 lead EKG machines. RN, LVN, and CMAs can all perform EKG. Each lead or electrode sees the flow of electrical current from a different angle. This picture shows the placement of the limb and precordial leads. You will learn these when studying for the APAR class.

Reading the EKG Paper

o Horizontal Axis Vertical Axis o Represents: Time Voltage o Small Box: 0.04 sec. 0.1mV o Large Box: 0.20 sec. 0.5mV

o Speed: 25 mm/sec.

EKG paper consists of a series of vertical & horizontal lines. Each of these lines forms blocks. The larger block is made up of 5 smaller blocks.

EKG paper moves through a recorder at a speed of 25 mm/second. The paper is heat sensitive therefore, if you leave a strip in sunlight the paper will turn black and you will loose the rhythm.

How to Measure the EKG Waves and Complexes To measure the PR Interval you begin at the P wave and end at the beginning of the QRS complex. It normally measures 0.12 – 0.20 seconds. To measure the QRS Interval you begin with first wave of QRS and measure the end of QRS. It is normally measures 1.4 – 0.12 seconds.

The ST segment tells if the patient is having any problems such as a heart attack.

Basic Steps of EKG Recognition There is a systematic approach to EKG interpretation. You will want to first look at the rate, then rhythm. You would want to look at the shape of the P waves. They should be nice, upright and rounded. All the P waves should look the same. The next thing you would do is measure the PR interval and QRS complexes.

We have already discussed the length of the PR interval and QRS complexes, lets look at the rate and rhythm in more detail.

Cardiac Rates The normal rate for EKG rhythms is between 60-100 b/m, a rate < 60 is bradycardic and > 100 is tachycardic. You can determine the rate by several methods. Most EKG paper has six-second marks on the paper. To count the rate in beats/minute using the “six second method” just count the number of QRS complexes in a six second strip then

multiply by 10. Heart rate calculator rulers are available but usually get “lost”. Another method is called the, “quick check method”. This is an approximation of the heart rate. You count the number of large blocks from one R wave to the next R wave and divide by 300 or you can count back the number of big blocks from one R wave to another by 300, 150, 100, 75, 60, etc.

Analyzing Cardiac Rhythms To analyze the rhythm you want to measure the R - R interval to determine if the rhythm is regular. You can simply do this by observation or by marking 2 sets of R waves on the edge of a sheet of paper then moving it down an EKG strip to see if the marks match. It is not uncommon for people to have an occasionally irregular rhythm (smoking, caffeine, elderly, exercise, etc) but an irregularly irregular rhythm shows signs of a chaotic or random beat which is not normal.

Variations in QRS Complexes Not all EKG rhythm patterns look the same. If you have had heart damage in the past (ie. Myocardial infarction or heart failure) you’re EKG may look different. That is why a lot of cardiologists like to get a “baseline” EKG on people and compare it when they are having chest pain.

Also, your heart pattern looks different depending on what lead you look at. The flow or angle of the electrical current can create a different “axis” so that the waves may look different. The standard lead to view heart rhythms is “Lead II”. Lead II looks along the normal conduction pathway of the heart with the negative lead at the upper right chest (or right arm) and the positive lead is at the apex of the heart (or left leg).

You are now prepared to review cardiac rhythms.

Normal Sinus Rhythm (NSR) Normal Sinus Rhythm is the “normal heart rhythm” that you would want to see each and every time you place a person on the monitor. The rate is between 60 and 100 b/m (beats/minute). The rhythm is regular. Notice the P waves are all upright, regular, and look alike. The PR Interval is between 0.12 & 0.20 secs. The QRS Complex is nice and tight with an interval of 0.12 sec. This is the base from which we shall name other rhythms.

Dysrhythmias or Arrhythmia “Dysrhythmias” or “arrhythmias” are abnormal heart action due to variation of rate, rhythm, or impulse conduction. Dysrhythmias can originate any where in the heart’s conduction system path. It is important to know that cardiac dysrhythmias may be recognized from a single lead, but more complex dysrhythmias or special problems require a 12 lead EKG.

Quick Review: The relationship of cardiac anatomy to the EKG tracing is very important. This helps you to recognize where the problem is in the heart based on the abnormality you see on the EKG tracing. For example, if you see a problem with the P waves, you know you are having a problem with the conduction in the atria; if you see a problem with the QRS complexes, you know you are having a problem with the ventricles.

Examples of Dysrhythmias Originating in the Atrium.

Sinus Bradycardia This rhythm originates from the SA node. Many well-conditioned and healthy individuals have a resting rate < 60 b/m. Some causes can be increased parasympathetic tone, disease of the SA node, and drug effects. Some of the clinical significance of Sinus Brady is that it can result in a decreased cardiac output, hypotension, angina, and CNS symptoms.

If the heart rate is getting slower, and the patient starts missing beats, they could be developing a “heart block”. This is an emergency situation where a patient might need a pacemaker. They should be transferred to the ER stat.

Sinus Tachycardia Sinus Tachycardia occurs when the heart rate is >100 b/m. The causes could be:

exercise

fever

anxiety

hypovolemia

anemia

pump failure

increased sympathetic tone

Sinus tachycardia usually occurs as some sort of compensatory response. We treat these patients by finding out the underlying cause then treat the cause. If the heart rate

>140 b/m, cardiac output may fall and the patient may experience angina or develop an acute myocardial infarction.

Atrial Flutter The causes of Atrial Flutter are mitral or tricuspid valve heart disease, and coronary heart disease.

The Rules of Interpretation are:

Rate - Atrial 250-350

Ventricular rate will vary

Rhythm - Usually regular unless ventricular response is variable

Clinical Significance: It is generally well tolerated with normal ventricular response. Fast ventricular rates can cause a decrease in cardiac output. Most people describe this rhythm strip as being “saw tooth” or “picket fence” P and T waves.

Atrial Fibrillation Atrial Fibrillation is very disorganized atrial activity with multiple areas stimulated in the atria causing the absence of P waves. It is usually the result of underlying heart disease such as rheumatic or atherosclerotic heart disease.

The rules of interpretation are:

Rate - Atrial 350-750

Ventricular rate varies

Rhythm - Irregularly irregular

Clinical Significance: Rapid rates can cause a decrease in cardiac output of approximately 30% and lead to CHF and predispose a patient to pulmonary emboli.

Dysrhythmias Originating from the Ventricles Now let’s look at dysrhythmias originating from the ventricles

Premature Ventricular Contractions (PVCs) Premature Ventricular Contractions (PVCs) are impulses that originate in either ventricle. PVCs indicate that there is some kind of irritability in the ventricles. A few PVCs may be common but too many can become lethal because it can lead into a more serious fast ventricular rate called, “Ventricular Tachycardia..

The causes of PVCs are:

myocardial ischemia

hypoxia

electrolyte imbalances

acid-base imbalances

The rules of interpretation are:

Rate - Depends on underlying rhythm

Rhythm - Interrupts regularity of underlying rhythm

P waves - None

P-R Interval - None

QRS complex - Greater than 0.12 seconds

Clinical Significance: As previously mention PCVs do indicate ventricular irritability & may trigger lethal arrhythmias. They are often classified as either malignant or benign. Please pay attention to PVCs if you have more than 6 per minute, experience the R on T phenomenon (when the R wave of the “QRS in the PVC” runs onto the “T-wave of the preceding beat” which can lead to V Tachy), couplets or runs of V-tach (a lot of PVCs in a row), and multifocal PVCs, that is, PVCs that are initiated from different areas of the ventricle and look different.

Ventricular Tachycardia (V Tachy) V Tachy consists of three or more PVCs in a row with a rate of > 100 b/m. Causes can be myocardial ischemia, hypoxia, acid-base disturbances, electrolyte imbalances, and R on T phenomenon. The rules of interpretation are:

Rate - 100-250 per minute

Rhythm - Usually regular

Clinical Significance: A patient may or may not have a pulse when they initially go into V Tach. This rhythm results in poor stroke volume and cardiac output. We do know that they can not survive long in this rhythm and usually go into Ventricular Fibrillation.

Ventricular Fibrillation (V Fib) In V Fib, the heart appears to be quivering with no rhythmic activity. The chaotic electrical activity in the ventricles is due to many reentry circuits. The most prevalent cause of V Fib is advanced coronary artery disease. The rules of interpretation are:

Rate - No organized rhythm

Rhythm - No organized rhythm

Clinical Significance: V Fib is a lethal arrhythmia where there is no cardiac output or organized electrical activity therefore, immediate defibrillation is required.

Asystole With Asystole, there is an absence of all electrical and mechanical function in the heart. It is referred to as the “rhythm of death”. It is usually associated with myocardial infarction, ischemia, and necrosis and is often a result of ventricular fibrillation.

Clinical Significance: Asystole results in cardiac arrest with a survival rate of only 1-2%. It is standard practice that if you are in this rhythm for 10 minutes and do not get a response, the resuscitation effort is terminated.

Emergency Cardiac Care Review the Facility level 9-1-1 that is attached at the end of this presentation. It stresses that you must begin CPR at the scene. It is also mandatory that that you sign the form and return it to your supervisor annually. This is usually done when you renew your CPR certification or at the time of your annual skills review.

Also, review UTMB’s CMC, “D-27.5 Standing Delegated Orders for Chest Pain” to utilize when caring for an offender with acute chest pain. This document is attached at the end of this presentation.

Causes of Artifact When obtaining EKGs, we want to get the best tracing possible. This can be done by decreasing the amount of electrical signals. There are several things we can do to eliminate “artifact”. For example, removing excess hair and prepping the skin allows the electrode gel to better penetrate the skin, thus receiving a stronger signal with less artifact. You may want to remove excess oil on the skin.

We will discuss the four main causes of artifact which are, patient, cable, and vehicle movement, and EMI in greater detail.

Patient Movement Make the patient as comfortable as possible. This will reduce muscle tension and will help to prevent artifact. Place the patient in the supine position if possible. If you cannot place the patient in the supine position, document the patient position during acquisition of 12 Lead ECG.

When performing the EKG check for subtle movement. Toe tapping or shivering can interfere with the reading. Also look for muscle tension such as the patient hand grasping the bed/stretcher rail or they are raising their head to “watch” what you are doing. Keeping the patient’s arms resting on a steady surface can also reduce artifact.

Cable Movement You want the patient cables to lay comfortable on the patient. You don’t want it too tight or too slack. Tight cables are uncomfortable to the patient and pulling of the cable ends can damage the cable. Too much slack can also create a trip hazard.

Electro-Magnetic Interference (EMI) EMI is the interference that comes from electrical equipment. It can cause failure of monitoring equipment. That is why you are asked to turn off electrical devices while aircraft are taking off or landing. Some of the more common causes of EMI comes from cell phones, radios, and fans

Strategies for Preventing EMI

Make sure patient cables do not touch power cords

Move away from AC equipment

Turn off or remove devices

Move away from areas with electrical “noise”

Make sure these devices are turned off when you are obtaining an EKG. You have successfully reviewed the basic EKG interpretation class! At that time, you will need to take a short test. Good luck!

Rev – 2/18

Attachment B, E-41.2

FACILITY LEVEL 9-1-1

As an employee of UTMB-CMC you are expected to respond to an emergency with the appropriate protective equipment and begin CPR as needed.

Telephone Call If you answer a call for help, tell the caller, “DO NOT hang up until you have been told to do so”. Get all pertinent information from the caller, such as:

The caller’s name

Location of the emergency

Phone number extension to area of emergency

How many victims

What the caller can tell you about what they see, hear, feel, and smell concerning the scene and victim

If you are the one to respond or are helping with the emergency, be prepared with the necessary equipment to perform CPR, including the Automated External Defibrillator, (AED) and the Emergency Response Bag. Medical personnel will take the AED on all calls requiring a cell side or on site response.

It is your responsibility to have immediate access to a CPR barrier device or have one on your person at all times while you are outside the medical department where they are readily available. CPR barrier resuscitation devices are available in various locations throughout the facility. It is your responsibility to know where the equipment is located and how to use it correctly. Scene Think “Scene Safety”. Whether that scene is at cell side or in the medical department, your safety comes first – dead heroes can’t save lives. In general population areas Correctional Officers are allowed to open cell doors but a correctional supervisor must be present in order to have cell doors opened in restrictive housing. Once you are on the scene, if you determine more equipment or personnel are required, send someone for what is needed. DO NOT ABANDON THE PATIENT! CPR If the patient is not breathing and has no pulse:

Start CPR and apply AED immediately. Do NOT allow security to move the patient until CPR is initiated.

Follow verbal prompts from AED.

Continue CPR en route to the infirmary/clinic.

Once the patient has arrived to the infirmary/clinic, CPR must continue until: 1. The patient revives; 2. EMS or other medical staff take over 3. An onsite provider pronounces the patient’s death; or 4. A physician pronounces the patient’s death by telephone.

My signature below verifies that I have read and fully understand the above information and understand that I must start CPR at the scene. ____________________________________ __________________________________ Print Name Print Title and Facility ____________________________________ __________________________________ Signature Date