Wrappin’ Up Rhythm – ECG that is…

1. Wrappin’ Up Rhythm – ECG that is…

2. Degrees of Dysrrhytmias • Minor: Does not significantly reduce Cardiac Output • Major: Significant reduction in Cardiac Output and coronary blood flow • Lethal: Cardiac Output is negligible

3. Examples of “Minor” Dysrrythmias: • Atrial Fibrillation • Atrial output is negligible but only contributes 20-30% to total CO • Occassional to frequent PVC’s* • Atrial Flutter • PJC, PAC * In otherwise uncompromised heart

4. Examples of Major Dysrrythmias: • Supraventricular Tachycardia: • Sinus Tachycardia* • Paroxysmal Atrial Tachy (PAT) • Paroxysmal Junctional Tachy (PJT) • Atrioventricular Block: R- R rate is between 20-40 • Extreme Bradycardia • *Coronaries fill between T- P waves (Diastole)

5. Examples of Lethal Arryhthmias: • Cardiac Output is negligible • Sustained V-Tach • V-Fib • Ventricular Standstill/Asystole: “Flat Line”

6. More on PVC’s • PVC’s are “ubiquitous” and usually “innocuous” • Easy to Spot: No P wave and wide and bizarre QRS complex • Generally followed by Compensatory Pause:Impulse doesn’t pass retrograde back to AV node, must “wait” for SA node to reset

7. However: • 80-90% of Infarcting patients have them: Some are more “ominous” than others: • Multiform (focus) • 2+ consecutive PVC’s • “R - on – T” • PVC is so early it initiates V-Fib

8. The Prognostic Strength of PVC’s • Not “Independent” predictors • BUT when accompanied by • Infarction • Ischemia • LV dysfunction • PVC’s of LV Foci (+ in V1) • Should Not Be Ignored!

9. CONDUCTION ARRHYTHMIAS Springhouse: Chapter 8

10. Ectopic Focus or Conduction Disturbance? • Ectopic Beats: • Premature and/or wide QRS complexes • Absent and / or abnormal P waves • AV Blocks: • Prolonged P-R intervals • Irregular P:R ratios • Ventricular blocks: Bundle Branch Blocks • Wide QRS / Normal P-R

11. Bottom Line: • The Speed of conduction in the Atria and ventricles is similar (Very Fast) • The AV Node Necessarily slows down conduction to allow time for the ventricles to fill before contraction • About 50% of the cardiac cycle is “held up” at the AV-Node

12. BLOCKS: • Conduction is slowed or interrupted • A-V Blocks occur in the conduction between the atria and ventricles • Ventricular Blocks: Occur in the Bundle Branches

13. 12 Lead ECGClinical Exercise Electrocardiography Springhouse: Chapter 11 and Brubaker et. al: Chapter 6

14. Clinical Indications for Exercise Testing: • Diagnosis: Reproduce symptoms • CP, SOB, Poor work tolerance • ECG changes? • Functional Testing: • Work Capacity, BP response to exercise, Exercise duration • Prognosis: • AHA, AACVPR, ACP: Risk Stratification, Duke’s 5-Year Mortality prognosis (Brubaker Chapter 7)

15. Diagnosis: • Indications: • Confirm or rule out suspected myocardial ischemia • Mechanisms for syncope (LOC) • Suspected arrhythmias (palpitations with symptoms) during exercise

16. Functional Capacity: • Indications: • Assessing work capacity for return to work/leisure activites • Used in determining risk/prognostic stratification • Used in determining therapy choices • Exercise Prescription: Phase II Entrance requirements

17. Prognostic Benchmarks • <5 METs: poor prognosis especially under 65 years old • 10 METs: considered normal fitness: survival good – regardless of intervention • 13 METs: good prognosis even with CAD present

18. Contraindications: • ACSM Guidelines • Co-existing conditions or unstable cardiovascular status • Recent AMI • Unstable angina • CHF • RBP >200/120 • Active infections • Uncontrolled Diabetes, other endocrine disorders

19. Stress Test Protocols • ACSM • AHA • Modalities • Bicycle Ergometer • Treadmill

20. Less expensive Less space Quieter Less ECG artifact Easier BP’s Non-Weight dependent More flexibility in protocols More reproducible (not-patient dependent) More accurate work determinations Bike vs. Treadmill

21. Disadvantages? Homework – Due Tuesday • Brubaker: Chapter 6 • List the disadvantages of each modality • Describe the variables monitored and the recommended intervals for monitoring them before, during and after the test

22. Treadmill Protocols: • Treadmill Speed: Individualize • Increment Size: Age, condition • Larger incremental increases for younger, more fit patients • Smaller incremental increases for elderly, de-conditioned • Test Length: • Between 8-12 minutes

23. Estimating Work Capacity: Selecting Protocols • Healthy Men >40 years old • 75% have 12.5 MET capacity • 50% ~ 10 METs • Healthy Women >40 years old • 75% have 10 MET capacity • 50% ~8-9 METs • Choose a protocol that achieves the estimated MET capacity between 8-12 minutes

24. Commonly Used Clinical Protocols: • Naughton: 2.0 mph X 3.5% increases every 2 minutes • Max METs = 9 /16 minutes • Balke: 3.3 mph X 3% increases every 3 minutes • Max METs = 12 /18 minutes • McHenry: Similar to Balke but Stage I is 2.0 mph/3% grade

25. Critical Measurements: • Work Loads: MET calculations • ECG: Clean ST-Segment changes • BP: Accurate work SBP/DBP • RPP: MVO2 eliciting CP • Elicited Symptoms: CP, SOB, Syncope, RPE

26. Rating Anginal Symptoms: • 1+: Light, barely noticeable • 2+: Moderate, bothersome • 3+: Severe, very uncomfortable • 4+: Most severe pain ever experienced

27. Exercise Test Endpoints: • Pre-determined HR achieved • Pre-determined Workload achieved • Patient c/o CP, SOB, leg pains, fatigue • ECG changes: • Significant ST changes • New Bundle branch or AV block • Increasing PVC frequency, VT or Fib

28. Post Exercise Period: • For Maximal Diagnostic Sensitivity: • No Cool Down • 10-sec ECG immediately • 6-8 minutes of supine monitoring* - record ECG every minute or after any irregularity *Unless patient is severely dyspneic – then sitting preferred

29. Testing Competencies: • Know Absolute and Relative indications for test termination: • 3+ to 4+ angina • Suspected MI • Drop in SBP with increased work • Serious arrhythmias • Signs of poor perfusion • Patient request

30. 12-Lead ECG Interpretations

31. Why a 12-Lead ECG? • Gives a “3-D” view of the heart • Especially important in revealing ischemia / infarct • Is more sensitive in assessing LV function

32. Prepping the Patient: • Electrode Sites: • Flat, Fleshy (not over bone/large muscles • Shave excess hair • Clean excess oil – alcohol scrub • Respect Modesty! • Use a drape • Explain procedure

33. 12-Lead ECG: Electrode Placement • RA/LA: • On Shoulders at distal ends of clavicles: (Not over large muscle masses or directly over bone) • RL/LL: • Base of Torso: Just medial to the iliac crests • Chest Leads: V1-V6 • Traditional pre-cordial positioning

34. V1-V2: 4th intercostal space –R/L of sternum V4: 5th intercostal space – midclavicle line V3: Between V2 and V4 V5: At horizontal level of V4, anterior to axilla V6: Midaxillary at horizontal level of V4

35. Terminology: • Lead: Recording the wave of depolarization between negative and positive electrodes • Einthoven Triangle: An equilateral triangle depicting the leads of the frontal plane (I-III and aVR – aVL) • Frontal Plane: Vertical plane of the body, separating the front from back • Transverse Plane: Horizontal plane separating the top from the bottom

36. Frontal Plane Leads: • Standard (bipolar) Leads: • I: RA- to LA+ • II: RA- to LL+ • III: LA- to LL+ • Augmented Vector (Unipolar) Leads • aVR: to RA+ • aVL: to LA+ • aVF: to LL+

37. Blue Segment: -30° to +90° Is normal “QRS axis”

38. QRS Axis? • Used to determine right or left heart hypertrophy or other anatomical anomalies • But How do we Determine Axis?

39. The heart is situated in the chest at an angle from right arm to left hip: Waves of Depolarization Travel from the Right shoulder To the left hip.

40. The ECG deflection (-/+) is determined by the direction of the depolarization wave relative to the “reading” or POSITIVE electrode

41. Like So: ECG: Depolarization wave - + Lead I - + + -

42. Normal QRS Deflections (ve = + / -) Check Leads: I and aVF Positive: Leads I-III, aVL, aVF, V4-V6 Negative: avR, V1-V2 Both Negative and Positive: V3

43. The Following Quadrant System Quickly Identifies QRS Axis Deviation

44. Interpreting Axis Deviation: • Normal Electrical Axis: • (Lead I + / aVF +) • Left Axis Deviation: • Lead I + / aVF – • Pregnancy, LV hypertrophy etc • Right Axis Deviation: • Lead I - / aVF + • Emphysema, RV hypertrophy etc.

45. NW Axis (No Man’s Land) • Both I and aVF are – • Check to see if leads are transposed (Did you reverse the RA and LL electrodes?) • Indicates: • Emphysema • Hyperkalemia • VTach

46. “Seeing” the heart in the Transverse plane: The Chest Leads V6 + V5 + V4 V1 V3 + - + V2 -

47. ST Segment Analysis: Ischemia Diagnosis • Key Reference Points: • Isoelectric line: Use the PR segment as reference • J-Point: Point at which QRS complex ends and ST segment begins • Most Common Measurement: • .06-.08 sec (>1-2 mm) past J-Point • ST Slope: Downsloping > Horizontal > Upsloping (questionable/angina)

48. ST – Depression:

49. ST-Depression • >1.0 mm depression: • Downsloping: Very predictive • Horizontal: Very predictive • Upsloping: Predictive if angina present • >2.0 mm depression • Usually indicative of ischemia

50. Positive Co-Conditions – Signals More Severe CAD: • Exertional Hypotension • Angina that limits exercise • Exercise capacity < 6 METs • ST changes at RPP < 15,000 • ST changes persist into recovery