1. Myocardial Infarction
Heart Disease
Myocardial Infarction

2. Myocardial Infarction
Heart attack
Leading cause of death in the US
Usually caused by an occluded vessel
Males more often affected until later in life

3. Assuming the individual survives the MI:
18 to 24 hours:
The damaged heart tissue will appear pallor (white in color, not pink)
2 to 4 days:
The dead tissue will appear yellow-brown and soft

4. 10 days:
Scar tissue forms at the margin of the infarction
Called metaplasia

7. Metaplasia
Replacement of one type of mature differential (specialized) cell into another type (due to injury)
Scar tissue (fibroblast cells) forms—you can often see the nuclei of these cells

8. Symptoms: Intense, crushing pain located below the sternum
Pain often radiates down left shoulder, arm, or jaw
Breathlessness
Anxiety
Nausea
Vomiting
Perspiration

9. Many people do not realize they are having heart attacks
Mistake symptoms for indigestion

10. After the onset of a MI, there may be no obvious problemsOr
Arrhythmias or pump failure may occur

11. Before we begin arrhythmias, how does a normal heart function and how does the pattern appear on an EKG?

12. Each heartbeat originates as an electrical impulse from a small area of tissue in the right atrium: sinus node
Impulse is a wave of negative ions

14. The impulse travels cell by cell to the atrioventricular node —a cluster of cells in the center of the heart (the only electrical connection between the heart chambers)
It travels along the Bundle of HIS

15. The impulse is delayed at the atrioventricular node until the atria fully contract.
The atria fully contract before the ventricles are stimulated.

16. Heart

17. An EKG consists of 12 leads that can pick up these negative ion waves
We mainly focus on only one lead (called lead 2)

18. Normal Heart Pattern on an EKG ©http://students. med. nyu

19. P wave: atria depolarize (release of ions and contraction of atria)
QRS complex: ventricles depolarize
Spike appears because there are many more heart cells depolarizing
Release of ions and contraction of ventricles
T wave: repolarization of the ventricles
Getting ready for the next heartbeat

20. PQRS: indicate systole
T: indicates diastole

22. How would an atrial problem look on an EKG?
How would a ventricular problem look on an EKG?

23. Deep Q
Shows an old infarction
Person had a MI in the past
The deeper the Q, the greater the infarction

25. Arrhythmia Irregular heartbeat
This is what usually kills the individual

26. The MI acts as an extra pacemaker—releases negative ions

28. There are different types of arrhythmias
Can be seen on an EKG

29. People die because the cells cannot control these ions, not because of the damage to the heart

30. Types of Arrhythmias Flutter Mild quivering of atria or ventricles
Fibrillation
Entire chamber of the heart undergoes quivering with chaotic impulses
Can affect the atria or the ventricles

31. Types of Arrhythmias Atrial fibrillation
Atria only pumps approximately 30% of blood into ventricles—the rest “falls out” (churning)
Most people survive this
Problem? thrombus may form

32. Thrombus may form

33. Types of Arrhythmias
Most individuals are on an anticoagulant (blood thinner)
Usually seen in older people
Not typically associated with MIs

34. Types of Arrhythmias Ventricular fibrillation Very dangerous—why?
No blood is really pumping

35. Types of Arrhythmias On board How would you describe this to a doctor?
ST problem —elevated ST segment
Very significant problem
The heart is in ischemia usually due to a clot

37. Nicknamed Tombstone Effect
Looks like a headstone
If you can get the person anti-thrombolic drugs soon enough, he should be okay
If not, heart will go into ventricular fibrillation

39. How do we stop fibrillation?
Defibrillate
“Knocks” out all of the ions and starts over
Person flat lines—heart stops and then restarts itself with a normal pattern

41. Only use a defibrillator if the person is in fibrillation
Can implant a defibrillator into a person’s chest

42. Types of Arrhythmias PVC: pre-ventricular contraction
Has been seen in teenagers, but most outgrow it
Not good in older people

44. Types of Arrhythmias Tachycardia
Any heart rate faster than 100 beats/min
Brachycardia
A slow rhythm, less than 60 beats/min

46. Treatment for Arrhythmias
Treatment: Pacemaker
Can speed up the heart, slow down the heart, assist with irregular beating
Most pacemakers also have a defibrillator

47. Implanted Defibrillator

48. Long QT Syndrome

49. Ruptured Septum after MI ©http://www-tc. pbs

50. For MI Lab Normal Heart Tissue

51. 3 Days After MI

52. Normal vs. Infarction

53. Vocabulary
Intercellular spaces:
Edema:
Leukocytes:

54. Vocabulary
Metaplasia:
Ischemia:
Infarction: