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Translation: Ch. 37

Translation: Ch. 37. C. Matthews RN, MSN Spring 2009. Hot link with simple explanation re: heart function. http://www.youtube.com/watch?v=D3ZDJgFDdk0. Terms to understand ( pages 708-709). Automaticity = spontaneity

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Translation: Ch. 37

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  1. Translation: Ch. 37 C. Matthews RN, MSN Spring 2009

  2. Hot link with simple explanation re: heart function • http://www.youtube.com/watch?v=D3ZDJgFDdk0

  3. Terms to understand ( pages 708-709) • Automaticity = spontaneity • Heart’s pacemakers working spontaneously and repetitively (without any outside assistance – you don’t have to think about it, it just happens)

  4. Terms to understand ( pages 708-709) • Excitability = response • The heart muscle cells respond to the electrical signals the pacemaker sends out

  5. Terms to understand ( pages 708-709) • Conductivity = transmission • The heart’s ability to make the electrical signals move from one cell to the next

  6. Terms to understand ( pages 708-709) • Contractility = shortening • The ability of the muscle cells in the heart to shorten when they get the electrical ‘message’ to contract.

  7. Polarization • At rest, the nerve cells are polarized. • Na (sodium) likes Nature – so he’s on the outside. • K (potassium) likes the Kitchen – so he stays inside • They are like 2 boxers, in their separate corners of the ring…waiting….

  8. Depolarization • When SA node rings the bell…the ions move (depolarization) and the ‘fight’ (current) begins • Like the bar fights in movies…the fight moves from one cell to the next (the domino example in a couple of slides will illustrate this)

  9. Depolarization • Where the “fighting” passes; the muscle cells are excited into contracting.

  10. Repolarization • When the fight stops and they go back to their separate places… the cells are repolarized... polarized again.

  11. The ECG complexes (page 712) • wavebreakmedia.com • The dominoes standing represent the “resting membrane potential” (page 709) – these are the heart nerve cells waiting for an electrical message from the SA node. • The SA node is the guy who pushes the first domino down – he started the electrical impulse that travels throughout the heart, creating the contractions (the pumping action) of the muscles.

  12. The ECG complexes • “Depolarization” is when ions move across the nerve cell’s membrane and create the electrical impulse – the impulse moves down the line like the dominoes falling one after the other. The impulse travels to the heart muscles and “excites” them into contracting.

  13. Atrial contraction • Remember on slide 6…Where the “fighting” passes; the muscle cells are excited into contracting. • While the electrical current moves from the SA node to the AV node…the atrial muscles contract.

  14. The P wave = Atrial depolarization(page 712) • The ECG (or EKG) is a picture of the electrical activity in the heart. • The P wave represents the start of the depolarization by the SA node. • The P wave represents when the SA node Pushes the first domino to start the string of domino falling.

  15. Watch the dominoes again… • wavebreakmedia.com • See the pause between when you see the dominoes falling toward the right and then they begin to fall toward the left? • There is a similar pause when the electrical stream gets to the AV node. Remember, he’s a supervisor that has to decide what to do with the electrical current the SA node sent him. It takes him a split second before he sends the message via HIS bundle to the rest of the heart.

  16. The PR segment • This is usually a line that stays on the base line of the ECG showing the time between the SA node Pushing the first domino (depolarization) the impulse finally reaching the AV node’s office, while it waits for orders from AV and travel time to get all the way to the Purkinjes.

  17. The PR interval • An interval is a certain amount of time. • The P wave + the PR segment = PR interval

  18. The PR interval (page 712) • The PR interval measures the time it takes for the atrial depolarization (atrial contraction) (the P wave) + the time it takes for the impulse to travel from SA’s office to AV’s office including the delay time the impulse sits in AV’s office while he makes the work assignments to pass on through the bundle of HIS (the PR segment).

  19. PR interval P = atrial depolarization ______ PR segment = electrical impulse travels to AV node ______ PR interval

  20. “Atrial kick” (page 709) This is one last push by the atrium to get as much blood into the Ventricles as possible just before they contract. The delay at the AV node allows for this.

  21. QRS complex (page 713) • QRS represents the ventricular depolarization which makes the ventricular muscles excited enough to contract.

  22. QRS • The electrical impulse was delayed at AV node’s office then traveled through the septum down to the apex and back up the R and L sides (i.e. the Purkinje fibers). (see figure 37-1 on page 709) • Both ventricles don’t contract simultaneously…nearly…but not quite.

  23. T wave • The T wave shows ventricular repolarization • This occurs after the muscles have been excited by the electrical wave and the ions go back to their separate places

  24. U wave The U wave represents late ventricular repolarization – it isn’t always present. Hypokalemia can cause slow repolarization – so the U wave might be prominent if there is not enough K to go back into the Kitchen after the electrical impulse passes.

  25. Lead ‘views’ (page 710) • Look at the pictures under the section called “Lead Formation Of The Limb Leads” • @ • www.nursce.com/x_courses/1071/1071.htm

  26. Bradycardia -Pg 715 • Like the Bradys… Slow • heart rate < 60 BPM http://www.edmorales.net/uploaded_images/brady-bunch-2-727995.jpg

  27. Tachycardia -Pg 715 Your heart Races… >100 BPM Tacky Tourist Adult Costume1600 x 1600 - 309k - jpgwww.buycostumes.com

  28. Practice NCLEX questions from the Saunders Comprehensive Review Book • The nurse is reviewing the EKG strip. The P waves and the QRS complexes are normal. The PR interval is 0.16 second and QRS complexes measure 0.06 second. The overall heart rate (HR) is 64 beats per minute. Which of the following would be a correct interpretation? • 1. Sinus bradycardia • 2. Sick sinus syndrome • 3. Normal sinus rhythm • 4. First-degree heart block

  29. Be careful not to accidentally take this as a negative type question. • B. The P and QRS are “normal” – you know these represent atrial and ventricular depolarization and contraction – so if these are okay then you can safely assume that there is no problem with contraction, so you can options 2 & 4, since they have to do with electrical current issues. • C & D. The book says that the measurements and the HR given are within normal limits, so there is no bradycardia (eliminate option 1) • Ta-da! By a process of elimination, you have correclty chosen option 3 – NSR. Question analysis • The nurse is reviewing the EKG strip. The P waves and the QRS complexes are normal. The PR interval is 0.16 second and QRS complexes measure 0.06 second. The overall heart rate (HR) is 64 beats per minute. Which of the following would be a correct interpretation? • A. Circle the word correct – You are looking for a right answer. • B. note that the P & QRS are “normal” • C. On pages 715-716 the book tells you the meaning of the measurements (PR interval is 0.16 second and QRS complexes measure 0.06 second) • D. Note the HR is given – see what is considered to be a normal HR on page 716,

  30. A client is wearing a continuous cardiac monitor which begins to alarm. A nurse sees no EKG complexes on the screen. Which of the following should be the priority action of the nurse? • 1. Call a code blue. • 2. Call a physician. • 3. Check the patient status and lead placement. • 4. Press the recorder button on the EKG console. Option 1: This seems a little drastic PLUS it is an intervention. Assessment comes before intervention…since this is a priority question, I’d look for an assessment answer before choosing this one. Option 2: another intervention. I’m not calling the doctor until I know what to tell him/her about the patient and the question doesn’t tell me enough to have the “SBAR” conversation on the phone with the physician. No. I’ve narrowed it down to option 1 or 3 and since option 3 is an assessment action as well as being way less drastic than number 1, the correct choice is option 3. Option 3 This seems reasonable. The screen could go blank if the leads have come off. I need to take a look at the client anyway. This is a possibility. Option 4: Um…no. It’d be nice to have a recording of what’s going on…but if the patient’s dead and all I did was record it, the only one who will want to see the recording is his lawyer!

  31. A client’s IKG strip shows atrial and ventricular rates of 110 beats/min. The PR interval is 0.14 second, the QRS complex measures 0.08 second and the PP and RR intervals are regular. How should the nurse correctly interpret this rhythm? • Sinus arrhythmia • Sinus tachycardia • Sinus bradycardia • Normal sinus rhythm

  32. Question analysis • A client’s EKG strip shows atrial and ventricular rates of 110 beats/min. The PR interval is 0.14 second, the QRS complex measures 0.08 second and the PP and RR intervals are regular. How should the nurse correctly interpret this rhythm? • Sinus arrhythmia • Sinus tachycardia • Sinus bradycardia • Normal sinus rhythm By eliminating the incorrect answers, because you need the correct interpretation, you have arrived at the correct answer…option 2. The measurements given in the question are all WNL according to page 716 and the intervals are regular…so option 1 is out because arrhythmia is the opposite of regular. Option 4 won’t work because NSR will have a normal HR (60-100). Options 2 and 3 are opposites. Only one, if either, can be correct. Since the HR is >60 BPM, option 3 is wrong. Cross it off. Option 2 could be correct because a HR > 100 is tachy.

  33. Repetitive rhythms (pages 717-718) • Bigeminy • Trigeminy • Quadrigeminy – you got the idea….

  34. Atrial fibrillation (page 727-728) • Watch the video on the following hot link: • http://video.google.com/videosearch?q=atrial+fibrillation&hl=en&emb=0&aq=0&oq=atrial#

  35. Atrial vs Ventricular fibrillation (pages 727-732) • Imagine you own a restaurant. • Ideally you want a steady stream of customers coming in who want to eat complete meals and pay well. • This is the same as a steady flow of blood entering the atrial chambers of the heart and moving smoothly into the ventricles and the ventricular chambers sending blood out successfully to either the lungs or the body.

  36. Atrial vs Ventricular fibrillation • But, if your customers come in erratically and you don’t have a steady stream of customers…you can still stay in business…you just might not make as much money. • It is the same with AFib…the atria not contracting regularly or as effectively may not be life-threatening immediately…but it definitely affects how well your heart and body get oxygenated blood.

  37. Another problem r/t A fib • If the atria are quivering and not effectively contracting and sending blood into the ventricles…the blood is kind of sitting around. Just like your restaurant customers would become unhappy if left sitting in the atrium too long…the blood gets unhappy and can begin to clot. These clots, if they escape the atria can cause heart attack, stroke, pulmonary emboli…serious problems. • This explains why you can expect clients with A fib to likely be treated with some sort of anticoagulant therapy. (page 728)

  38. Atrial vs Ventricular fibrillation • If you have a steady number of customers coming into your restaurant but once they get seated they decide they don’t want to eat and/or don’t want to pay…then your business is not going to last and you will go broke. • This would be similar to Vfib – the atrial muscles are working fine or at least able to get the blood into the ventricles but the ventricular muscles are not contracting properly…this is a medical emergency!

  39. Ventricular fibrillation (page 731-732) • The symptoms of Vfib are similar to your restaurant situation…if customers are coming in but refusing to be seated or order or are paying erratically…there will be chaos (AEB the chaotic ECG). • Your business will become weak. You will feel faint when you count your receipts. Rather quickly your business will be unconscious – no money coming in and bills to pay…which will make you short of breath. The restaurant will become very quiet…just like no BP or heart sounds in V fib.

  40. References • Ignatavicius, D.D. & Workman, M. L. (2006). Medical-Surgical Nursing. (5th Ed.) Elsevier-Saunders, St. Louis, Missouri. • Silvestri, L. A. (2008). Saunders Comprehensive Review for the NCLEX-RN Examination. (4th Ed.). Elsevier-Saunders, St. Louis, Missouri. • Heart function video retrieved 1/5/09 from http://www.youtube.com/watch?v=D3ZDJgFDdk0 • Photos retrieved from Tacky Tourist Adult Costume1600 x 1600 - 309k - jpgwww.buycostumes.com and http://www.edmorales.net/uploaded_images/brady-bunch-2-727995.jpg • Domino illustration retrieved 1/5/09 from wavebreakmedia.com • http://video.google.com/videosearch?q=atrial+fibrillation&hl=en&emb=0&aq=0&oq=atrial# • Lead Formation Of The Limb Leads” retrieved 1/5/09 from www.nursce.com/x_courses/1071/1071.htm

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