Common

1. Common Cardiac Arrhythmias Nursing 519A SS 8/14

2. Expected Individual Student Learning Objectives • Label and discuss the anatomy of the heart • Label and describe the purpose of the conduction system • Identify the wave forms and measurements of Normal Sinus Rhythm • Identify the following rhythms • Sinus Bradycardia • Sinus Tachycardia • Supraventricular Tachycardia – Atrial Tachycardia • Paroxysmal Atrial Tachycardia • Atrial Flutter • Atrial Fibrillation

3. EISLO Label and discuss the anatomy of the heart

4. Anatomy of the Heart • The adult heart is about the size of a closed fist and sits in front of the lungs but behind the sternum, in a space called the mediastinum. The majority of the heart is located to the left of the sternum. • The atria are located at the anatomical base of the heart, while the ventricles are located at the anatomical apex of the heart. The superior and inferior vena cava, right atrium, and part of the right ventricle are located under the sternum. The apex of the heart, also the point of maximal intensity, is located at the fifth intercostal space, mid-clavicular line. midclavicular line http://www.healthline.com/vpvideo/how-the-heart-works

5. The heart is a pump that contains four chambers – right atrium (RA), right ventricle (RV), left atrium (LA), left ventricle (LV). • The right atrium and right ventricle work as one unit to receive de-oxygenated blood from the body and pump it to the lungs where it exchanges carbon dioxide for oxygen. The muscles in the right ventricle are relatively small because the pressure in the lungs is weak. • The left atrium and left ventricle work as one unit to receive the oxygenated blood from the lungs and pump it out to the body. The muscles of the left ventricle are about twice as big as those of the right because it has to generate enough force for the blood leaving the heart to reach all parts of the body. • The heart also contains four valves. Two on the right and two on the left. • The valves, under normal conditions, insure that the blood can only flow in one direction. • The tricuspid valve is located between the right atrium and right ventricle, the pulmonary valve is located between the right ventricle and pulmonary artery leading to the lungs. • The mitral valve is located between the left atrium and left ventricle, the aortic valve is located between the left ventricle and the aorta which leads to the body.

6. Function of the Heart • The function of the heart is to circulate blood throughout the body. To do this it receives blood from the body, sends it to the lungs, then sends it out to the body again full of oxygen • A cardiac cycle consists of the following steps: • Blood enters the atria (right and left) at the same time; ventricles are at rest or diastole • Tricuspid & mitral valves open, 75-80% of blood falls into ventricles by gravity; ventricles are at rest or diastole • Atria contract, pushing the remaining 20-25% of blood into the ventricle – this is called atrial kick • Ventricles contract and push the blood volume into the lungs (from the right side) or into the aorta ( from the left side); ventricles contracting or systole • Stroke volume = amount of blood ejected by the ventricles each time they contract

8. Electrolytes • Three major electrolytes responsible for cardiac conduction and contraction. • Sodium (Na+) • Potassium (K+) • Calcium (Ca+) • Balance is required to maintain electrical conduction through the myocardium. • When electrolytes get out of balance there is the potential for serious dysrhythmias. There must be an electrical impulse for a mechanical event to occur

9. Potassium Imbalance

10. EISLO Label and describe the purpose of the conduction system

11. CARDIAC CONDUCTION SYSTEM L. Bundle Branch Junction L. Bundle Branch

12. Myocardial Action Potential • Depolarization • Phase 1 of the action potential • Stimulation of the cardiac cell by the pacemaker cell causing an influx of Na and Ca, outflow of K. • Repolarization • Phase 2 of the action potential • No impulse entering the cells can cause it to depolarize • Relative refractory period • Phase 3 of the action potential • Impulses entering the cardiac cell now can cause serious, uncontrolled reactions. • Absolute refractory period • Phase 4 of the action potential • The return of the cardiac cells to resting state.

13. ABSOLUTE-RELATIVE REFRACTORY PERIODS ABSOLUTE • The muscle is drained and needs a moment to recharge • An impulse sent to a muscle during this phase would not cause it to contract • From the beginning of the Q to the middle of the T wave RELATIVE • The cell is not fully charged but will still attempt to contract if stimulated • An impulse during this period can cause premature contractions leading to compromised filling and poor ejection of blood from the heart • It can also lead to life-threatening arrhythmias that severely compromise the hearts ability to pump and death can occur quickly • Think of this as flushing a toilet…..when the tank is emptied you can push the handle down but it will not flush again Absolute Relative

14. Autonomic Nervous System Sympathetic Nervous System Originates from thoracic vertebrae Responsible for “fight or flight” response Causes blood pressure to rise; pulse to go faster; pupils to dilate; respiratory rate to deepen and get faster; blood is shunted from “non-essential functions” Triggered by: • Fear • Stress • Pain • Exercise • Drugs (prescription/non-prescription) • Caffeine • Nicotine Parasympathetic Nervous System Originates from carotid arteries called vagal nerve Responsible for “rest & digest” response Causes blood pressure to decrease; heart rate slows; respiratory rate slows; blood is moved to bowels, bladder to enhance digestion; an overall energy conservation occurs Triggered by: • Carotid massage • Valsalva maneuver • Abnormal or sudden rise in blood pressure • Pain • Nausea/vomiting • Medications

15. EISLO Identify the wave forms and measurements of Normal Sinus Rhythm

16. Putting it all together • The SA Node fires, stimulates the atria to contract • This creates the P wave and tells us the atria have depolarized

17. When the impulse reaches the AV node it is held for a fraction of a second • This creates the P-R interval which represents atrial depolarization and repolarization- the time it takes for the impulse to travel from the SA node to the AV node Bundle of His • The impulse leaves the AV node and travels through the Bundle of His, Bundle Branches and Purkinje Fibers • This stimulates the ventricles to contract creating the QRS complex representing ventricular depolarization

18. Components of the EKG • P wave • Depolarization of the atria • QRS • Depolarization of the ventricle • T wave • Repolarization or resting phase of the ventricle • PR Interval • Delay in the AV node to allow the atria to contract • ST Segment • represents early phase of ventricular muscle recovery • QT Interval • Represents the total time for ventricular depolarization and repolarization. It should be no longer than ½ of the R-R interval • Isoelectric Line • Baseline or starting point for eachcomponent Isoelectric line

19. Other Important Components • T Wave • T wave corresponds to ventricular repolarization • Usually rounded and upright • T waves that are inverted, peaked, or flattened may be due to electrolyte imbalance, hyperventilation, CNS disease, ischemia or MI • Occasionally a U wave is visible following the T wave, it is smaller and represents repolarization of the Purkinje Fibers

20. EKG Paper • EKG paper runs at 25 mm/sec • EKGs are read left to right and are measured in seconds V O L T A G E TIME

21. Telemetry • Electrodes – disc shaped patches with conduction gel in the middle of the disc • Electrodes allow conduction of the electrical impulses from the patient into the machine for visualization • Leads – carry the electrical impulses to the monitoring equipment • Skin Preparation • Artifact – occurs when an electrode gel has dried up or with patient movement

22. White Lead Black Lead RA LA Brown Lead V1 Red Lead RL LL Green Lead White lead – right upper chest wall Black lead – left upper chest wall Green lead – right lower chest Red lead – left lower chest Brown lead – right side of sternum 4th intercostal space White clouds above the green grass, black smoke over the red fire, brown is the trunk of the tree

23. 5 Lead Set-up Lead V1 Leads II, III Lead I

24. Positive and Negative Deflections QRS complexes can be above or below the isoelectric line depending on the flow of electricity across the heart P, T and U wave inversion (negative deflection) is not normal

25. Rhythm“Marching Out” R waves are the same distance apart

26. Rate • If the rhythm is irregular the most accurate method to determine the rate is auscultation of the apical pulse • This is a Nursing “standard of care” • Apical pulse is located at the point of maximal intensity (PMI); 5th intercostal space, mid-clavicular line. 6-SECOND STRIP METHOD • This is the least accurate method • Identify (2) 3 second markers (total of 6 seconds) • Count the number of R wave complexes • Multiply this by 10 = the approximate number of beats per minute 6 seconds 3 seconds

27. Memorization Method Division Method This is the most accurate method Count the number of small boxes between 2 R waves Divide 1500 by the number of boxes # of small boxes 1500

28. Division Method This is the most accurate method Count the number of small boxes between 2 R waves Divide 1500 by the number of boxes # of small boxes 1500 = 55 OR # of .20 boxes 300 = 60

29. P Waves • Are P waves present? • Do they have a positive or negative deflection • Is there one in front of each QRS (1:1) • Remember that the P wave represents Atrial depolarization PR Interval The SA node fires, atria contract, impulse travels to the AV node where it is held for a fraction of a second, this creates the P-R interval – atrial depolarization and repolarization Prolonged P-R interval can be indicative of impaired AV node conduction Measure from the beginning of the P-wave to the beginning of the QRS Normal range is .12 – .20

30. QRS Complex • Represents ventricular depolarization • Impulse leaves AV node, travels through the Bundle of His, Bundle Branches and Purkinje Fibers stimulating the ventricles to contract • Measure from the negative deflection of the Q to where the S meets the isoelectric line. If no Q wave is present measure to the R wave. • Normal range is ≤ .12 seconds

31. Q-T INTERVAL • Average Range .34 - .44 this measurement varies with heart rate • A measurement of >.47 indicates possible myocardial problems • >.50 is in the danger zone • Begins at the Q wave and ends at the end of the T wave. • The most accurate measurement of the QT is the QTc (c means corrected) interval. QT(c) = QT interval √RR interval • Or said another way: The QT interval divided by the square root of the R to R interval

32. EKG Interpretation-Criteria • General rules • Read each strip left to right • Be consistent look at each wave form and measurement across the strip • Learn normal parameters • Rhythm • Regular or irregular • Rate • Calculate the rate • P waves • Present? • Upright? • 1 in front of each QRS? • PR Interval .12-.20 • QRS complex • Narrow, look the same • Measurement < .12 • QT Interval • .34 - .44

33. Sinus Rhythms Normal Sinus Rhythm • Rhythm – Regular • Rate – 60 – 100 bpm • P waves – upright and matched 1:1(each QRS is preceded by a P wave) • PR Interval – .12 – .20 • QRS Duration - ≤.12 • QT Interval - .34 - .44

34. EISLO Identify the following rhythms • Sinus Bradycardia • Sinus Tachycardia • Supraventricular Tachycardia (Atrial Tachycardia) • Paroxysmal Atrial Tachycardia • Atrial Flutter • Atrial Fibrillation

35. Sinus Bradycardia • Same criteria as Sinus Rhythm except • The rate is < 60 (40-59) Sinus Tachycardia • Same criteria as Sinus Rhythm except • The rate is > 100 (101-140)

36. Sinus Arrhythmia • Rhythm – slightly Irregular, varies with respirations due to vagal stimulation • Rate – variable • P waves – A P wave precedes each QRS complex. All P waves look alike an all are upright • PR Interval – .12 – .20 • QRS Complex - ≤.12 • QT interval - .34 - .44 inspiration expiration speeds up slows down

37. Supraventricular Tachycardia (SVT)Atrial Tachycardia • Rhythm – Regular • Rate – >150 bpm • P Waves • Due to fast rate the T and P are together in one waveform • PR and QT interval not measurable • QRS Complex - ≤.12

38. Paroxysmal Atrial Tachycardia PAT has a sudden onset, the heart resolves the problem without intervention • Rhythm – Regular with an underlying rhythm • Rate – >150 bpm– theheart resets the rate by itself • P Waves • Due to fast rate the T and P are together in one waveform • PR and QT interval - not measurable in the SVT state but the parameters can be measured in the underlying rhythm • QRS Complex - ≤.12

39. Atrial Flutter • Rhythm – regular or irregular • Rate – variable • P waves • Sawtooth in shape • PR interval and QT interval not measurable • QRS Complex- ≤.12

40. Atrial Fibrillation • Atrial fibrillation is the chaotic depolarization of the atria. The result is a very disorganized EKG rhythm • Rhythm – always irregular • Rate – variable • P Waves – isoelectric line appears to be undulating, chaotic, no organized or identifiable wave forms • PR and QT interval – not measurable • QRS Complex - ≤.12

41. Lethal Rhythms you need to recognize Ventricular Tachycardia Ventricular Fibrillation Asystole