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Interpretation of an EKG Strip

6. Interpretation of an EKG Strip. Interpretation of an EKG Strip. Objectives Recall the general rules to use when correctly identifying heart rhythms Describe the basic approach to interpretation of EKG strips Discuss the five steps used in interpretation of EKG strips.

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Interpretation of an EKG Strip

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  1. 6 Interpretation of an EKG Strip

  2. Interpretation of an EKG Strip • Objectives • Recall the general rules to use when correctly identifying heart rhythms • Describe the basic approach to interpretation of EKG strips • Discuss the five steps used in interpretation of EKG strips

  3. Interpretation of an EKG Strip • Objectives • Explain how to calculate heart rate, given a 6-second strip • Name four causes of artifact

  4. General Rules • First and most important, look at your patient • Read EVERYstrip from left to right, starting at the beginning of the strip • Apply the five-step systematic approach that you will learn in this chapter • Avoid shortcuts and assumptions

  5. General Rules • A quick glance at a strip will often lead to an incorrect interpretation • Ask and answer each question in the five-step approach in the order that is presented here… this is important for consistency

  6. General Rules • Master the accepted parameters for each dysrhythmia and apply them to each of the five steps when analyzing the strip

  7. The Five-Step Approach • This five-step approach, in order of application, includes analysis of the following • Step 1: Heart rate • Step 2: Heart rhythm • Step 3: P wave • Step 4: PR interval • Step 5: QRS complex

  8. Step 1: Heart Rate • Number of electrical impulses as represented by PQRST complexes conducted through the myocardium in 60 seconds (1 min) • Atrial rate • Counting the number of P waves noted • Ventricular rate • Counting the number of QRS complexes noted

  9. Heart Rate • SA node discharges impulses at a rate of 60–100times per minute • Bradycardia • Heart rate less than 60 BPM • Tachycardia • Heart rate greater than 100 BPM

  10. Heart Rate Determination • Two methods of determination of the heart rate • The 6-second method • Denotes a 6-second interval on EKG strip • Strip is marked by 3-or 6-second tick marks on the top or bottom of graph paper • Count the number of QRS complexes occurring within the 6-second interval and then multiply that number by 10

  11. Sample of 6-Second Method

  12. Two Methods to Determine Heart Rate • Two methods of determination of the heart rate • Second method is theR-R interval method • Most accurate if heart rate is regular • An estimation of the heart rate

  13. Two Methods to Determine Heart Rate • Two methods of determination of the heart rate • Second method is the R-R interval method • Look at QRS complex that falls on a heavy line on the strip, count number of large boxes between this R wave and the next R wave • Dividethis number into 300

  14. Sample Strip for R - R Method

  15. STEP 2: Heart Rhythm • Rhythm • Sequential beating of the heart as a result of the generation of electrical impulses

  16. STEP 2: Heart Rhythm • Classified as • Regular pattern • Intervals between R waves are regular • Irregular pattern • Intervals between R waves are not regular

  17. Regular Rhythm • Measure the intervals between P to P waves or R to R waves

  18. Regular Rhythm • If the intervals vary by less than 0.06 seconds or 1.5 small boxes, we can consider the rhythm to be regular

  19. Irregular Rhythm • If the intervals between the P to P waves or R to R waves are variable by greater than 0.06 seconds, rhythm is considered irregular • Regularly irregular • Irregular rhythms that occur in a pattern • Occasionally irregular • Intervals of only one or two R to R are uneven

  20. Irregular Rhythm • If the intervals between the P to P waves or R to R waves are variable by greater than 0.06 seconds, rhythm is considered irregular • Irregularly irregular • R to R intervals exhibit no similarity

  21. Practice Strip for Rate and Rhythm Analysis

  22. Practice Strip for Rate and Rhythm Analysis

  23. STEP 3: The P Wave • P wave is produced when the right and left atria depolarize • First deviation from the isoelectric line • Should be rounded and upright • P wave is SA node pacing or firing at regular intervals • This pattern is referred to as a sinusrhythm

  24. STEP 3: The P Wave

  25. P Wave: Five Questions to Ask • Step 1: Are P waves present? • Step 2: Are P waves occurring regularly? • Step 3: Is there one P wave present for each QRS complex present and/or is there a QRS for each P wave present?

  26. P Wave: Five Questions to Ask • Step 4: Are the P waves smooth, rounded,and upright in appearance, or are they inverted? • Step 5: Do all P waves look similar?

  27. P Wave Practice Strip

  28. STEP 4: The PR Interval • Measures the time interval from the onset of atrial contraction to onset of ventricular contraction • Measured from onset of P wave to the onset of the QRS complex • Normal interval is 0.12–0.20 seconds (3–5 small squares)

  29. STEP 4: The PR Interval

  30. PR Interval: 3 Questions to Ask • Are PR intervals greater than 0.20 seconds? • Are PR intervals less than 0.12 seconds? • Are the PR intervals constant across the EKG strip?

  31. PR Interval Practice Strip

  32. STEP 5: The QRS Complex

  33. STEP 5: The QRS Complex • Represents depolarization or contraction of the ventricles • Q wave • First negative or downward deflection of this large complex • R wave • First upward or positive deflection following the P wave (tallest waveform)

  34. STEP 5: The QRS Complex • Represents depolarization or contraction of the ventricles • S wave • The sharp, negative, or downward deflection that follows the R wave

  35. QRS Complex: 3 Questions to Ask • Are QRS intervals greater than 0.12 seconds (wide)? • Are QRS intervals less than 0.12 seconds (narrow)? • Are the QRS complexes similar in appearance across the EKG strip?

  36. Sample QRS Rhythm Strip

  37. The ST Segment

  38. The ST Segment • Begins with the end of the QRS complex and ends with the onset of the T wave (consistent with isoelectric line) • J-point • Point at which the QRS complex meets the ST segment

  39. The ST Segment • If ST segment is elevated or depressed, myocardial ischemia or injury may be indicated

  40. The T Wave

  41. The T Wave • Produced by ventricular repolarization or relaxation • Commonly seen as the first upward or positive deflection following the QRS complex

  42. The U Wave • Usually not visible on EKG strips • Cause or origin not completely understood • Typically follows the T wave • Appears much smaller than T wave, rounded, upright, or positive deflection if they are present

  43. Artifact • EKG waveforms from sources outside the heart

  44. Artifact • Interference seen on a monitor or EKG strip • 4 causes • Patient movement • Loose or defective electrodes (fuzzy baseline) • Improper grounding (60 cycle interference) • Faulty EKG apparatus

  45. Sample Rhythm Strip of Artifact

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