Transcript of Cardiac Ecg Interpretation
- 1. What you will learn Understanding preload, afterload, and
contractility. Phases of the cardiac cycle (revision) Linking the
phases to the ECG How electrolyte imbalances affect ECGs Acute
AF,MI,
- 2. http://www.skillstat.com/Flash/h eartscape_2004.html Testing
your cardiac knowledge!
- 3. Preload, afterload & contractility. If you think of the
heart as a balloon, it will help you understand stroke volume!
- 4. Phases of the Cardiac Cycle. What can you remember? Do not
worry how many phases there are, as long as you remember the
process
- 5. Phase 1 Are the A-V Valves open or closed? Are the Semilunar
Valves open or closed? Is this polarization or depolarization of
the Atrial? The pressure within the atrial chambers increase or
decrease? (remember balloon) What part of the ECG does this
represent?
- 6. Where do I start! P-wave is the depolarization of the Atrium
QRS-wave is the depolarization of the Ventricles There should be
one P-wave to each QRS Normal P to R interval should be less than
0.2 seconds or five little boxes Normal QRS interval should be less
than 0.12 seconds or three little boxes Normal heart rate is 60-100
Bradycardia is heart rate less than 60 Tachycardia is heart rate
greater than 100
- 7. Simplified! Step 1. Is the speed of the rhythm between
60-100? Step 2. Is it regular? Step 3. Is the complex narrow? Step
4. Is it preceded by a P-wave? Step 5. Do all the complexes look
the same?
- 8. Let us now look at a normal ECG trace.
- 9. How does the ECG work?
- 10. Vertical and horizontal perspective of the leads. The limb
leads view the heart in the vertical plane and the chest leads in
the horizontal plane
- 11. Unipolar, Bipolar and Precordial leads. The word leads is
misleading. Sometimes it is used to mean the pieces of wire that
connect the patient to the ECG recorder. Properly, a lead is an
electrical picture of the heart.
- 12. Sinus Rhythm Sinus denotes that the rhythm of the heart is
still being generated by the sinuatrial node, so the P-wave and QRS
complex are generally normal.
- 13. Sinus Rhythm
- 14. How electrolyte imbalances affect ECGs The electrolytes
sodium, potassium, and calcium, with the help of magnesium, shift
back and forth across myocardial cell membranes. This shifting of
electrolytes causes alternating periods of activity
(depolarization) and rest (repolarisation), which allow for normal
myocardial function.
- 15. Hypokalemia Serum potassium < 3.5 mEq/L Ventricular
repolarisation is prolonged. The ECG shows a characteristic U wave
Ectopic impulses develop in the myocardium A rhythm strip may show
ventricular ectopy Potentially fatal arrhythmias such as
ventricular tachycardia.
- 16. Ventricular ectopics
- 17. Ventricular Tachycardia
- 18. Ventricular Tachycardia
- 19. Anyone want to hazard a guess?
- 20. Hyperkalemia Serum potassium > 5.5 mEq/L A tall tented T
wave AV or ventricular block may develop Flattened P wave A
prolonged PR interval A widened QRS complex Depressed ST segment
Severe Hyperkalemia > 9 mE/L causes the P wave to disappear, the
QRS complex to widen, and sine waves to form. Hyperkalemia may end
in lethal arrhythmias.
- 21. Atrial fibrillation
- 22. Atrial flutter
- 23. CASE STUDY A 58-year-old male, presents to ED with C/O
chest pain, with radiation to the Left arm and jaw. He reports
feeling anxious, diaphoretic, and SOB. His PMH is significant of
type II diabetes mellitus and hyperlipidemia. O/E, the patient
appears to be in moderate distress and anxious. His ECG shows
evidence of Acute MI in the inferior leads. The Dr. suspects that
the left anterior descending artery is involved.
- 24. Case study continued What would the ST segment of this ECG
look like? On which leads would you see this ST segment change?
What does the T wave represent
- 25. MI The normal electrocardiogram (ECG) pattern consists of a
P wave, a QRS complex, and a T wave (A). In patients who have an ST
elevation myocardial infarction (MI), the ST segment is elevated
above the baseline (B). In patients who have a non-ST elevation MI,
the ST segment is not elevated, and instead other patterns are seen
(for example, ST depression) (C).
- 26. Answers ST segment appearance: Elevation of the ST
segments. Inferior leads: II, III, and aVf T wave: Represents
ventricular polarizion.
- 27. ECG recognition quiz Choose one of the following answers (A
E) A. P wave B. PR wave C. QRS complex D. ST segment E T wave 1.
Period when ventricular action potentials are in their plateau
phase. 2. Prolonged during first-degree heart block 3. Produced by
depolarization of atrial fibers
- 28. Any question? To summarise: We have reviewed the
pathophsyiology of the heart. Wetted your appetite for ECG
recognition.