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 ECG Clinical 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. Bike vs.Treadmill 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

21. Disadvantages? Homework – Due Tuesday Brubaker: Chapter 6 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: 4 th intercostal space –R/L of sternum V4: 5 th 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: - + Depolarization wave Lead I ECG: -+ - +

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

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 V2 V1V3 V4 V5 V6 - - + + + +

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

51. Determining Regions of CAD: ST-changes in leads… RCA: Inferior myocardium II, III, aVF LCA: Lateral myocardium I, aVL, V5, V6 LAD: Anterior/Septal myocardium V1-V4

52. Regions of the Myocardium: Inferior II, III, aVF Lateral I, AVL, V5-V6 Anterior / Septal V1-V4