1. Basic Cardiology

4. The Heart Pericardium Epicardium Myocardium atrial muscle
ventricular muscle
conductive tissue
Endocardium

5. The Heart

6. Myocardium
branch
intercalated disks with gap junctions

7. Intercalated Disc

8. Electrical Stimulation of the Heart

9. Sinoatrial (SA) Node Right atrium Inherent rhythm 80-100 bpm)
Usually sets the heart rate (sinus rhythm)

10. Internodal & Interarterial Pathways
Anterior
Middle (Wenckebach branch)
Posterior
Interatrial
Anterior Interarterial band or Bachmann’s bundle

11. Atrioventricular (AV) Junction
AV Node
Located at the base of the right atria near the interventricular septum
Smaller cells, fewer gap junctions, slower
Maximal rate is ~230 per minute; also maximal ventricular rate

12. AV Junction AV Bundle or Bundle of His
Only cellular connection between atria and ventricles
Together with AV node make up the AV junctional tissue
Intrinsic heart rate of bpm
If SA node fails, AV junctional tissue can control heart rate
Slows down the cardiac impulse

13. Bundle Branches Right and left branches
Two left branches (sometimes three)
Left anterior fascicle or left anterior bundle branch; thinner, carries impulses to septum, left anterior wall, and anterior papillary muscle
Left posterior fascicle or l. post. bundle branch; thicker, carries impulses to posterior, inferior, left ventricular free wall and posterior papillary m. with dual blood supply, less likely to become ischemic,
Both left and right BB travel down towards the apex of the heart where they fan out into Purkinje fibers

14. Purkinje Fibers Pass through the ventricular myocardium
Contraction starts at the apex
Fast rate of action potential generation, numerous sodium ion channels and mitochondria and fewer myofibrils

17. Electrical Stimulation of the Heart
Video

18. “If you understand the normal physiologic stimulation of the heart, you have the basis for understanding the abnormalities of heart rhythm and conduction the produce distinctive ECG patterns.” p. 5

19. Electrocardiogram SA node AV node Bundle branches Purkinje fibers
Atrial depolarization Ventricle depolarization Ventricle repolarization
Bundle branches
Purkinje fibers

20. Electrocardiogram

21. Rhythms Normal conduction Sinus Rhythm Abnormal conduction
Junctional rhythm
e.g. escape pacemaker
Ventricular rhythm

22. Cardiac Conductivity SA node - slow Internodal pathways - fast
AV node - slow
Purkinje fibers - faster

23. Cardiac Automaticity Automaticity SA node - primary pacemaker
Other sites e.g. AV junction
Certain conditions increase the automaticity of ectopic pacemakers
Ectopic = outside of the sinus node pacemaker (non- sinus)

24. Abnormalities AV heart block = blockage of stimuli through AV junction
Bundle Branch Block = disease of bundle branches
ST segment changes = damage to ventricular muscle

25. Coronary Arteries

26. Coronary Arteries The Left Main (LM) Left Anterior Descending (LAD)
Left Circumflex (LCX).
The Right Coronary Artery (RCA)
The RCA on the posterior part of the heart is often called the Posterior Descending Artery (PDA), in most cases it originate from the RCA but in some cases it comes from LCX.

27. Coronary Artery Perfusion
LAD
Supply the anterior septum, the anterior wall, and in most cases apex. 9 o'clock to 1 o'clock.
LCX
Supply the lateral wall
2 o'clock to 4 o'clock
RCA
Supply the posterior lateral segments, the inferior segments, and the posterior septum.
5 o'clock to 8 o'clock

28. Class Organization Resting 12 lead ECG
Understanding normal 12 lead ECG and conditions that cause abnormal depolarization and repolarization
Recognizing abnormal rhythms and AV conduction disturbances
Associating the ECG arrhythmia with its pathology
Exercise ECG