EKG Plain and Simple, 4th Edition Class Notes

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11CardiacAnatomyand PhysiologyChapter SynopsisThis chapter covers basic heart structure and function, starting with a description of theheart’s layers and chambers and progressing to the cardiac cycle and a description of thephases of systole and diastole. It is meant to be very general as it is a basis for theelectrocardiography to be covered in later chapters. The instructor who wants more detailmay wish to refer to an anatomy or physiology text. The information in this chapter canusually be covered in one to two 75-minute classes.Chapter OutlineI.IntroductionII.Layers of the HeartA.EpicardiumB.MyocardiumC.EndocardiumIII.Heart ChambersA.Right atriumB.Right ventricleC.Left atriumD.Left ventricle

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2IV.Heart ValvesA.Semilunar valves1.Pulmonic2.AorticB.Atrioventricular valves1.Tricuspid2.MitralV.Great VesselsA.Superior vena cava (SVC)B.Inferior vena cava (IVC)C.Pulmonary arteryD.Pulmonary veinsE.AortaVI.Blood Flowthrough the HeartVII.The Cardiac CycleA.Diastole1.Rapid-filling phase2.Diastasis3.Atrial kickB.Systole1.Isovolumetric contraction2.Ventricular ejection3.Protodiastole4.Isovolumetric relaxationVIII.Blood Flow Through the Systemic CirculationIX.Coronary ArteriesA.Leftmain coronary artery(LMCA)a. Left anterior descending branchb. Circumflex branchC.Right coronary artery (RCA)

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3X.Heart CellsA.Contractile cellsB.Conduction system cellsXI.Nervous Control of the HeartA.Sympathetic nervous systemB.Parasympathetic nervous systemXII.Chapter 1 Notes—To Sum It All Up…XIII.Practice QuizXIV.Putting It All Together—Critical Thinking ExercisesChapter ObjectivesUpon completion of this chapter, the student will be able to:•State the location of the heart and its normal size.•Name the walls and layers of the heart.•Name all the structures of the heart.•Track the flow of blood through the heart.•State the oxygen saturation of the heart’s chambers.•Describe the function and location of the heart valves.•Describe the relationship of the valves to heart sounds.•List the great vessels and the chamber into which they empty or from which theyarise.•State what occurs in each phase of the cardiac cycle.•Name and describe the function of the coronary arteries.•Differentiate between the two kinds of cardiac cells.•Describe the sympathetic and parasympathetic nervous systems.•Describethefight-or-flightandrest-and-digestresponses.Frequently Asked Questions (FAQs) by Students•I know someone with an enlarged heart. What does that mean?Suggested answer: That means his or her heart is larger than average. This may bebecause of high blood pressure, other heart problems, or it could simply be normal

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4for them. An enlarged heart is not necessarily a problem. (As an instructor, youshould always encourage students with medical concerns to see their physician. Youshouldprovideonlygeneralinformation.Do notdiagnoseunlessyouareaphysician.)•How does the blood flow uphill from the legs to the heart? Because humans are erectbeings, it seems that gravity would tend to keep the blood in the legs and feet.Suggested answer: Arteries push the blood away from the heart under pressure—theblood pressure. Veins return blood to the heart without the benefit of this pressure.Three things enable venous blood to flow uphill against gravity. First, veins havevalves. That prevents the blood from backflowing. Next, the negative pressure in thethoracic cavity during the respiratory cycle essentially serves as a vacuum and“sucks” the blood uphill toward the heart. Finally, the muscles in the legs squeezethe leg veins, forcing the blood up toward the heart.•Do coronary arteries change during one’s life or are they a certain way from birth?Suggested answer: Individuals who have frequent coronary chest pain can developcollateral circulation, small tributary blood vessels that provide blood flow around anarrowed area of a major coronary artery. For most people, the coronary arteriesremain the ones with which they are born. Studies are under way to understand whatcauses angiogenesis, the development of new blood vessels.Suggested Class Activities•To illustrate the parasympathetic nervous system’s effect on the heart rate (the heartrate falls when the glottis is closed because a closed glottis causes vagus nervestimulation), have the students take a deep breath and then hold it while palpatingtheir pulse. The decrease in heart rate should be obvious. If you have access to acardiac monitor, attach a student volunteer to the monitor and record the decrease inheart rate during breath holding. Students always enjoy this, and it helps liven upwhat could be dry subject matter.•Have an anatomy/physiology bee. This is the equivalent of a spelling bee. Line thestudents up against the wall. Ask anatomy questions. Each student who answersincorrectly sits down. The last one standing is the winner.

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5•Hand out a blank heart diagram and have the students label the structures.•If you have access to a stethoscope, have the students listen to each others’ heartsounds.•Hand out a blank diagram of the coronary vessels and have the students label thecoronary arteries and veins.•Have the students point out the coronary arteries and heart structures on a heartmodel if one is accessible.Critical Thinking ExercisesAnatomy and physiology can be—let’s face it—pretty boring. Students can memorize thematerial in the chapter, but they need tounderstandthe clinical implications of anatomicand/or physiologic heart disturbances. This focus on “here’s the situation—what does itmean physiologically for the patient?” will help them later on in the rhythms chapters.Utilize the following scenarios or make up your own and have the students explain theanatomy and/or physiology behind the situations. The suggested answers are simply aguide for the instructor.•Mrs. Breaux has developed a heart rhythm that alters her heart’s physiology—she nolonger has atrial kick. Have the students explain what this means to the patient.Suggested answer: Atrial kick is the last phase of diastole—it accounts for 15–30%of ventricular filling. With a rhythm that does not allow atrial kick, the other phasesof diastole will occur as usual, but there will be no atrial contraction/atrial kick.Therefore, the ventricles will be less full when systole begins. This can cause a dropin the amount of blood expelled by the heart (cardiac output).•Mr. Thompson has a mitral valve that is stenosed (narrowed). Have the studentsexplain what happens to the left atrium as it struggles to pass its blood through thestenosed mitral valve.Suggested answer: Because the mitral valve is stenosed, it does not allow easypassage of blood through it. The left atrial muscle will,therefore,“bulk up” toenable it to contract more forcefully to force blood through the stenosed valve into

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6the left ventricle (just like the left ventricle has more muscle bulk than the rightventricle because it pumps against resistance).•Mr. Hopkins has been in an automobile accident. His arm is badly injured and he isbleeding profusely. Have the students explain what role the autonomic nervoussystem plays in the body’s initial response to this injury.Suggested answer: This is a classic fight-or-flight scenario. The sympathetic nervoussystem will trigger the adrenal gland to pour out norepinephrine, causing the heartrate and blood pressure to increase. With a large blood loss, the cardiac output willdrop, triggering the heart to speed up to circulate the remaining blood around faster.Crossword PuzzleThe crossword puzzle that follows can be used as a take-homeorin-class test, or justgiven out as practice.

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92ElectrophysiologyChapter SynopsisThis chapter covers the electrical events that control the cardiac cycle and introduces theEKG waves and complexes and the conduction system. Many practice examples enhancelearning. Two 75-minute classes should be enough to cover this chapter.Chapter OutlineI.IntroductionII.Depolarization and RepolarizationIII.The Action PotentialA.Phase 4B.Phase 0C.Phases 1 and 2D.Phase 3IV.Refractory PeriodsA.AbsoluteB.RelativeC.Supernormal periodV.EKG Waves and ComplexesA.P waveB.TawaveC.QRS complexD.T waveE.U waveVI.Waves and Complexes Identification PracticeVII.QRS Nomenclature

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10A.Q waveB.R waveC.S complexD.QS waveVIII.QRS Nomenclature PracticeIX.Cardiac Conduction SystemA.Conduction PathwayX.Cardiac CellsA.AutomaticityB.ConductivityC.ExcitabilityD.ContractilityXI.Inherent (Escape) Rates of the Pacemaker CellsXII.Conduction VariationsXIII.EKG PaperXIV.IntervalsA.PR intervalB.QRS intervalC.QT intervalXV.Intervals PracticeXVI.Chapter 2 Notes—To Sum It All Up…XVII.Practice QuizXVIII.Putting It All Together—Critical Thinking ExercisesChapter ObjectivesUpon completion of this chapter, the student will be able to:•Define the termspolarized, depolarization,andrepolarizationand relate them tocontraction and relaxation.•Describe and label the phases of the action potential.•Definetransmembrane potential.•Draw and explain the P wave, QRS complex, T wave, and U wave.

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11•Explain where the PR and ST segments are located.•Define theabsoluteandrelative refractory periodsand the implications of each.•Be able to label, on a rhythm strip, all the waves and complexes.•Explain the delineations of EKG paper.•On a rhythm strip, determine if the PR, QRS, and QT intervals are normal orabnormal.•Name the waves in a variety of QRS complexes.•Definepacemaker.•List the different pacemakers of the heart and their inherent rates.•Track the cardiac impulse from the sinus node through the conduction system.•Define the four characteristics of cardiac cells.•Describe the difference betweenescapeandusurpation.•Definearrhythmia.•Tell what happens:When the sinus node fails.When the sinus node and atria both fail.When the sinus node, atria, and AV node all fail.Frequently Asked Questions (FAQs) by Students•How can the Tawave be happening at the same time as the QRS complex?Suggested answer: The Tawave and the QRS complex represent events happeningsimultaneously in different chambers of the heart. These events do not cancel eachother out—they occur simultaneously. Because ventricular depolarization generatesa large amount of electrical current, it“swallows up”the Tawave that occurs at thesame time.•How can a rhythm have no P wave?Suggested answer: Some rhythms originate in different parts of the conductionsystem and do not depolarize the atria, thus no P wave is written. There are manyrhythms that have no P waves.

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12•Why is a purely negative QRS complex called a QS wave? Why not just Q or just Sinstead of both?Suggested answer: A Q wave is a negative wave that precedes an R wave. An Swave is a negative wave that follows an R wave (just as in the alphabet). If there isno R wave to go by, the negative wave can’t really be called a Q or an S, so acompromise is made and it is called QS.•What happens if all the pacemakers fail?Suggested answer: If all the pacemakers fail, there are no waves or complexes at allon the EKG printout. There is only a flat line to indicate the complete lack ofelectrical current in the heart. The patient in this case has no pulse,is notbreathing,and is clinically dead.•Can a pacemaker stop for a while and then “wake up” again?Suggested answer: Absolutely. In fact, that is a frequent occurrence. Hopefully, oneof the other pacemakers will keep things going until the faster pacemaker resumescontrol.•Do patients feel it when a different pacemaker takes over?Suggested answer: Patients do not feel the change in pacemakers per se. What theyfeel, if anything, is a change in heart rate, either faster or slower. Some patientsreportfeelingpalpitationswhenalowerpacemakerusurpsthepredominantpacemaker at a very rapid heart rate.And some patients feel a big thump when therehas been a long pause and an escape beat kicks in.This change in heart rate, eitherfaster or slower, can cause symptoms of low cardiac output.Suggested Class Activities•Hand out practice sheets with different QRS configurations and have the studentsname the waves.•Have students get into small groups and practice labeling the waves and complexesof various rhythm strips. The students who are catching on more quickly can helpthe slower ones.

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13•Have an electrophysiology bee. Line students up against the wall. Ask each student aquestion about electrophysiology. Students answering incorrectly sit down. The lastone standing is the winner.•If you have access to a rhythm simulator, show the students a sinus rhythm with arate between 60 and 100. Then show a junctional rhythm with a rate between 40 and60. Finally, switch to a ventricular rhythm with a rate between 20 and 40. This is agood way for the students to see what the slower heart rates caused by each lowerpacemaker look like.•Have the students label a diagram of the conduction system.•Have the students tracktheheart’scurrentfrom the sinus node through theconduction system to the ventricle.•Have four students stand in front of the class. Assign each one to be a pacemaker ofthe heart. Have a small ball on the table in front of them. Ask them to demonstratewhat happens in sinus rhythm. The sinus student should pick up a ball and hand it tothe atrium, who hands it to the AV node/junction, who hands it to the ventricle. Thestudent representing the ventricle jumps up and down to indicate depolarization.•Now ask them to demonstrate what happens when the sinus node fails. Typically,the next pacemaker in line to replace the failing sinus node is the AV junction. Thesinus node and atrium students should do nothing. The AV node/junction studentshould pick up the ball and hand it to the ventricle, who then jumps up and down torepresent depolarization.•You can make up more scenarios like this. It is undeniably corny, but it gets thestudents participating and makes them laugh (especially the poor student whorepresents the ventricle by jumping up and down).Critical Thinking ExercisesUtilize the following scenarios or make up your own to get the students thinking aboutelectrophysiology.•Mr. Miller’s heart monitor alarmed, showing his rhythm was a flat line. Have thestudentsexplainwhatishappening—ornothappening—electricallyandmechanically. Will he have a pulse?

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14Suggestedanswer:Mr.Miller’sflatlinetellsusthatnothingishappeningelectrically in his heart. There is no depolarization or repolarization. And if there isno depol/repol, there can be no mechanical response. The heart can’t pump if it hasnot been depolarized first. There will be no pulse.•Mrs. Tucker has a rhythm that has no P waves. Have the students explain what thismeans in terms of atrial depol/repol andthephases of diastole.Suggested answer: If there is no P wave, there is no atrial depolarization andtherefore no atrial contraction/atrial kick.This does not mean there is no bloodflow from atrium to ventricle. Blood flow from atrium to ventricle will still occurpassively as usual in the first phases of diastole. There will just not be the atrial kickto squeeze the last 15–30% of the blood into the ventricle.•Mr. Tart has a PR interval that has changed from 0.12 seconds to 0.24 seconds afterstarting a new medication. Have the students tell what this PR interval change meansphysiologically. Are the intervals normal or abnormal?Suggested answer: The increased PR interval means it takes the impulse longer toreach the ventricle than before the medication was started. The new PR interval isabnormally prolonged.Crossword PuzzleThe crossword puzzle below can be used as a take-homeorin-class test, or just given outas practice.

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173Lead Morphologyand PlacementChapter SynopsisThis chapter introduces leads and lead placement and describes what each lead of anormal 12-lead EKG should look like. With modern monitoring systems displayingmultiple leads during continuous monitoring, it is imperative that the student know thenormal QRS morphology of each lead. The information in this chapter can be covered inone or two 75-minute classes.Chapter OutlineI.IntroductionII. Lead TypesIII.Bipolar LeadsIV.Augmented LeadsV.Precordial (Chest) LeadsVI.Continuous MonitoringVII. The Most Commonly Used Leads for Continuous MonitoringVIII.Electrocardiographic TruthsIX.Normal QRS DeflectionsX.Chapter 3 Notes—To Sum It All Up…XI.Practice QuizXII.Putting It All Together—Critical Thinking ExercisesChapter ObjectivesUpon completion of this chapter, the student will be able to:

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18•Defineelectrode.•Name the bipolar leads and the limbs that comprise them.•Name the unipolar augmented leads.•Explain what augmentation does to the EKG.•Explain Einthoven’s law.•Draw and label Einthoven’s triangle.•Name the leads comprising the hexiaxial diagram.•Describe the location of the precordial leads.•Name the two leads most commonly used for continuous monitoring in the hospital.•Explain the electrocardiographic truths.•Describe the normal QRS complex deflections in each of the 12 leads on an EKG.Frequently Asked Questions (FAQs) by Students•If the morphology of a lead on the EKG is abnormal, what does that mean?Suggested answer: If the QRS morphology is abnormal, it could imply a defect inimpulse transmission through the bundle branches, it could imply an MI, or it mightindicate a normal variant. In addition, it could simply mean the leads were put onincorrectly (arm leads may have been reversed).•Why is the QRS in lead I supposed to be positive? The normal impulse is travelingtoward the foot, not toward the arm. Shouldn’t the QRS be negative?Suggested answer: The impulse does not have to be travelingdirectlytoward anelectrode in order for the lead to write a positive deflection. The impulse merely hasto be traveling in the same direction in which the positive pole of the lead is located.In other words, any limb lead whose positive pole is on the left side of the bodyshould have a positive QRS complex, because the normal impulse travels right toleft. That’s why all the frontal leads except AVR have a positive deflection.Suggested Class Activities•Hand out practice EKGs and have the students evaluate the QRS morphology.

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19•Use a rhythm simulator to show rhythms and ask the students if the QRS complexesare the correct morphology.•If you have access to a manikin or skeleton, have the students practice putting on theprecordial leads.•Have the students practice putting precordial leads on each other.•Using a student volunteer, or a manikin or skeleton, place precordial leads inincorrect locations. Have the students examine the lead placement, tell where theerror is, and then correct it.Critical Thinking ExercisesUtilize these scenarios or make up your own.•Mr. Thornton has a heart rhythm that originates in the left ventricle. Have thestudents tell how the frontal lead morphology should look and why.Suggested answer: Because Mr. Thornton’s current starts in the left ventricle, it willhead upward and to the right to depolarize the entire heart. Thus,the morphologywill be as follows: Ld I—neg, Ld II—neg, Ld III—neg, aVR—pos, aVL—neg,aVF—neg. AVRwill be the only positive lead because it is the only lead in whichthe positive pole is on the right arm where the current is traveling.•Mrs. Smith has had her left leg amputated just below the hip joint. There is notenough stump to put an electrode on. Where should her left leg electrode be placed?Suggested answer: Put the electrode on the abdomen just above where the leg wouldbe.Crossword PuzzleThe crossword puzzle that follows can be used as a take-homeorin-class test, or justgiven out as practice.

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224Technical Aspectsof the EKGChapter SynopsisThis chapter describes the function of the EKG machine and discusses some of its controlfeatures. It also discusses electrical safety and the different kinds of artifact that canimpact the readability of the tracing. Troubleshooting artifact is covered, along withpractice examples. Telemetry monitoring is discussed. Once armed with this knowledge,the class ideally will be able to practice performing EKGs. This chapter can be covered inone 75-minute class.Chapter OutlineI.IntroductionII.Control FeaturesA.Chart speedB.GainC.Frequency responseIII.Electrical SafetyA.MacroshockB.MicroshockIV.ArtifactA.Somatic tremorsB.Baseline swayC.60-cycle interferenceD.Broken recording

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23V.TroubleshootingVI.Artifact Troubleshooting PracticeVII.Artifact Masquerading as RhythmsA.Artifact masquerading as asystoleB.“Toothbrush tachycardia”C.CPR artifactD.Defibrillation/cardioversion artifactVIII.Artifact inThreeLeadsMonitoredSimultaneouslyIX.Is It Real or Is ItArtifact?X.Real or Artifact: How to Tell the DifferenceXI.Chapter 4 Notes—To Sum It All Up…XII.Practice QuizXIII.Putting It All Together—Critical Thinking ExercisesChapter ObjectivesUpon completion of this chapter, the student will be able to:•Identify the control features of an EKG machine and describe the functions of each.•Describe what a digital converter does.•Differentiate betweenmacroshockandmicroshock.•Describe and identify on a rhythm strip the different kinds of artifact.•Correctly tell how to troubleshoot artifact.•Tell how to differentiate between artifact and a real rhythm.•Correctly identify artifact versus rhythm.Frequently Asked Questions (FAQs) by Students•How can you tell if the EKG rhythm is real or if it’s artifact?Suggested answer: Some artifact, such as baseline sway, is very obvious and easilyremedied. Other artifact is less obvious. Some patients, for example, have finemuscle tremors that can make the rhythm look completely abnormal. It helps tocompare the present EKG to previous ones. If there is a big difference that does not

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24seem to jive with the patient’s clinical status, check your patient. If he/she hassymptoms of decreased cardiac output, the rhythm is probably real. Artifact does notproduce symptoms. If there are no symptoms, it would be wise to redo the EKG, justin case. Most of the time, though, the typical problems such as reversing the armleads are easily detected, because the QRS deflections will be backward from thenormal(and because modern EKG machines will indicate if leads are reversed).Remember the normal QRS deflections in each lead. If the QRS deflections havechanged from the last EKG, check your lead placement. If in doubt, redo the EKG.Suggested Class Activities•Give the students rhythm strips along with a scenario and have them determinewhether the rhythm is real or artifact. For example, show a strip ofwhat looks likev-tach and tell the class the patient is brushing her teeth and is awake and feelingfine.•Have the class act out various scenarios, using a rhythm simulator to show therhythm in question. Have the rest of the class decide whether the rhythm is real orartifact.•If there is a clinical component to the class, have the students collect strips of artifactin a rhythms scrapbook.•Dividetheclassintogroupsoffiveorsix.Askquestionsaboutartifactmasquerading as rhythms. Show rhythm strips. Each group must reach a consensuson the answer, and one spokesperson must give the group’s answer. Each correctanswer is worth 10 points. The group with the highest score wins.•Have the class practice doing a 12-lead EKG on student volunteers. Have thevolunteer then move his/her arms wildly, then in a tremulous manner to createartifact so the students can see what kinds of movements cause artifact and in whichleads the artifact is most noticeable.•Practice doing an EKG with the arm leads reversed, so the students see how it looks.•Ask the students what they would do if an EKG machine they were planning to usehad a broken grounding prong.

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25Critical Thinking ExercisesUtilize the following scenarios or make up your own.•Mr. Corwin had a heart attack and is recovering nicely. He is up brushing his teethwhen a nurse rushes in and asks him how he’s feeling. His heart rhythm looksdangerous. Mr. Corwin admits he feels lousy—dizzy, with mild chest pain and alittle shortness of breath. Ask the students whether they think the “dangerousrhythm” is artifact or real—or could it be both?Suggested answer: The rhythm could be real—Mr. Corwin is showing symptomsthat could correlate with his rhythm—or it could be that he indeed had “toothbrushtachycardia” and no rhythm problem at all. The symptoms he’s having could becompletely unrelated to the rhythm. The presence of artifact does not preclude thepossibility that there could be additional problems.•Mrs. Trahan has flat-line on the monitor. The nurse does not rush to the roombecause the patient has had a lot of artifact previously and the nurse thinks this isonce again artifact. She arrives in the room in due time to find the patient on thefloorincardiacarrest.Askthestudentswhattheythinkaboutthenurse’sassumption that this was artifact?Suggested answer:The students should realize that each time is different. Alwayscheck the patient immediately.Crossword PuzzleThe crossword puzzle that follows can be used as a take-homeorin-class test, or justgiven out as practice.

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285Calculating Heart RateChapter SynopsisThis chapter covers the different methods of heart rate calculation based on the type ofrhythm regularity. Many practice examples help the student learn both regularity andheart rate calculation. This material can be covered in two 75-minute classes, offeringplenty of time for practice.Chapter OutlineI.IntroductionII.Methods for Calculating Heart RateA.The 6-second strip methodB.The memory methodC.The little block methodIII.Regularity-Based Heart Rate CalculationIV.Regularity TypesA.RegularB.Regular but interruptedC.IrregularV.Practice Strips: Regularity of RhythmsVI.Kind of Heart Rate to Calculate for Different Types of RegularityA.For regular rhythmsB.For irregular rhythmsC.For rhythms that are regular but interrupted by premature beatsD.For rhythms that are regular but interrupted by pausesVII.Practice Strips: Calculating Heart RateVIII.Chapter 5 Notes—To Sum It All Up…

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