1. Electrophysiology of the Heart-Completed PDF

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Med Surg Review Dysrhythmias 1. STEP ONE: Watch This Video for MINT Nursing (12 mins): https://youtu.be/FThXJUFWUrw 2. Lectures for exam one: https://soundcloud.com/patty-cohen/sets/nurs-223-exam-1 3. Listen to Sinus to Atrial to follow along with this handout (may not go in exact order) 4. Definitions: Electrophysiology of the Heart see page 665 I and W 

Automaticity - (pacing function) ability of cardiac cells to generate an electrical impulse spontaneously and repetitively

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Excitability - ability of non-pacemaker heart cells to respond to electrical impulse that begins in pacemaker cells

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Conductivity – ability to send electrical impulses from one cell membrane to another

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Contractility- Mechanical function of the heart … ability of the atrial and ventricular muscle cells to shorten their fiber length in response to electrical stimulation, causing enough pressure to push blood forward through the heart.

5. Which one of these definitions refers to the mechanical function of the heart?  

Depolarization-contraction; the cardiac muscles conduct an impulse; systole Repolarization-relaxation or recovery; diastole

6. Normal Electrical Conduction through the Heart Intrinsic rates of the conduction system SA Node-Pacemaker 60-100 bpm AV Node-Gate Keeper ___40-60___ bpm Purkinje Fibers/Ventricle- __20-40___ bpm

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Sinoatrial (SA) node → intraatrial and internodal pathways → atrioventricular node (AV node) → bundle of His → bundle branches → Purkinje fibers → ventricular muscle

Mnemonic: On Saturdays, I Avoid Bee Hives with Bumble Bees in the Park Forest

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Med Surg Review Dysrhythmias 7. Watch this video Registered RN.com (10 mins): https://youtu.be/QAQiK-zRtl0 8. Fill in the blanks. What do the following waves/intervals represent?: Separate Waveforms page 667-669 I and W Repolarization = resting

Depolarization = contraction

Intervals = time it takes for signal to travel from one area to another. Abnormal times indicate pathological conditions. Short interval = fast HR 

P wave- represents atrial depolarization

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PR Interval (PRI)- SA to AV down to ventricles before contraction Q wave- 1st negative deflection. Ventricular depolarization. A pathological Qwave w/o ST changes means its from an old MI QRS complex- ventricular depolarization. Atrial repolarization takes place her but is covered by the complex (upside down V)

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ST Segment- isoelectric

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T wave- Ventricular repolarization (upright smooth and rounded)

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U wave- (late) Ventricular repolarization of the purkinje fibers. Its rare. Can be present in hypokalemia

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Long Interval =Slower HR/block

Med Surg Review Dysrhythmias 9. Time-pg 668 I and W Intervals PRI- 0.12-0.2 seconds (3-5 little boxes) QRS 0.04-0.08 or < 12 seconds Time is measured horizontally

10. What do intervals reflect? time it takes for signal to travel from one area to another Abnormal interval times indicate pathologic conditions. Interval PRI

Normal Conduction 0.12-0.2 Beginning of p to before QRS

Less than 0.12 seconds

QRS

Fast Interval

Slow (long) Interval

Short HR Less than 0.12

FasterHR/block Greater than 0.2

Conduction has increased and superventricular

SlowerHR/block Impuse coming from ventricles

Less than 0.04 11. Steps involved in interpreting a rhythm strip Follow these steps each time! MUST Watch this video: https://youtu.be/3QN0kzKYrdQ      

Determine the heart rate - count the # of Big boxes between QRS’s and divide by 300 (Which would look like 300/x) Determine the rhythm – regular or irregular Analyze the P waves Measure the PRI Measure the QRS complexes Examine the ST segment

12. Rate

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Med Surg Review Dysrhythmias

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Count the number of QRSs and multiply by ten

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works for both regular and irregular rhythms for a 6 second strip

13. Big block method for Heart Rate (watch Mint video again) 

The Big block method is only for regular rhythms (re-watch video if you missed how to calculate rate by big block method) 300 boxes in a minute

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March out the P to P waves and the R to R waves (described in You tube video)

15. Analyzing P Waves 

Are they upright? If its not upright & rounded its not from the SA node

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Are the rounded?

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Is there one for each QRS?

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Do they all look the same?

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Do you see flutter/fib waves?

16. Measure the PRI 4

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Measure from the beginning of the P wave to the beginning of the QRS Are they present? Are they equal (consistent)? Are they in the normal range? Represents the time taken for impulse to spread through the atria, AV node and bundle of His, bundle branches, and purkinje fibers, to a point immediately before ventricular contraction A PRI longer (slower)than 0.20 seconds indicates an AV block How many little boxes is a normal PRI? 3 to 5 little boxes

What does it indicate if there are fewer little boxes in the PRI? A PRI less than 0.12 seconds means Faster conduction from the SA node through the AV node to purkinje  17. Measure the QRS Complex     

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measured from the beginning to the end of the QRS. Normal range is 0.04-0.12 OR < 0.12 seconds Represents ventricular depolarization (atrial repolarization) Are the QRS complexes present? Do they all look alike? Are they narrow or wide. o If they are narrow super ventricular o If they are wide coming from ventricle Is there one QRS following each P wave?

Anything more than 0.12 can indicate a dysrhythmia such as PVC 18. QT intervals  Represents Ventricular depolarization and repolarization  Dependent on heart rate but a good guide is 0.34-0.43 seconds  Measure from the beginning of the Q wave to the end of T wave  Shortened QT intervals occur with hypercalcemia  Prolonged QT intervals occur with hypocalcemia  Medications also affect the QT  We will skip this step for most interpretations Short QT = high/long calcium Long QT = low/short calcium or antidysrhythmic meds 19. Examine the ST segment-see page 669  Represents the time during which ventricles are contracting and emptying  Should be isoelectric

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Med Surg Review Dysrhythmias

 Notice how the Q and the S are almost equal This is considered isoelectric

 20. ST elevation  Should not be elevated (greater than 1-2 mm; one to two little boxes vertically)  Elevation indicates myocardial infarction (2or more =stemi) OR pericarditis (ST elevation in all leads) Notice how the S wave is higher than the Q wave An increase of the ST segment > 1 mm is clinically significant “When myocardial tissue dies it goes to heaven.”

 21. ST depression  Indicates myocardial ischemia, hypokalemia, digitalis administration Note how the S wave is lower than the Q wave More than 1 mm to 2 mm depression is significant (1 to 2 little boxes vertically)

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Med Surg Review Dysrhythmias

22. What is a dysrhythmia? Any deviation from normal sinus rhythm 23. What is ectopy? What causes ectopy? Heart is acting crazy. Nicotine, old age

24. Why are dysrhythmias more common in older adults? they have less SA node cells

25. Test knowledge here: https://quizlet.com/_8bfktl?x=1jqt&i=1vndzv

26. Interventions for dysrhythmias  Assess first: Assess LOC, Circulation, Airway, Breathing (vitals)  If responsive and stable: monitor airway, breathing, and circulation  If symptomatic: Call Rapid Response Team (RRT)  Pulseless? start ACLS/BCLS  Apply O2-priority for chest pain  Obtain 12 lead ECG  Begin continuous ECG monitoring  *Identify the rate and rhythm; identify the dysrhythmia*-notice where this falls-you always, always. Always assess your pt first!  Establish IV access  Obtain baseline laboratory studies (CBC, electrolytes, possibly cardiac enzymes, coagulation studies)  Admin antidysrhythmic meds and analgesics  Determine the cause 27. Treatment for dysrhythmias  continue to monitor (investigate)  eliminate source  medications  electricity Try this escape room: https://forms.gle/3qEaez4FvZzEqLS87 Great job! Every Study session needs to be followed up with an assessment of your learning. Resources for assessments: Escape rooms when offered Saunders NCLEX Study book for your textbook (you should be doing these questions, as I write your exam questions from your textbook) ATI adaptive quizzes ATI practice exams 7

Med Surg Review Dysrhythmias

Signs Urinary output 0.5-1ml / hr Kidney receives 25% of blood Slow cap refill – except ppl w/ old age, Dm, PVD, or anemia a cap refill may not be accurate Palpitations Ectopy – caused by nicotine & old age, less sa node cells, fat deposits, caffeine, hypoxia, stress, drugs Digoxin – yellow green white halo lights, vomiting anorexia nausea (liver toxicity),

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