Introduction to Cardiology

1. Introduction to Cardiology EMS Professions Temple College

2. Introduction to Cardiology Cardiovascular Disease EMS System Role Cardiovascular A&P Cardiovascular Electrophysiology

3. Cardiovascular Disease Single greatest cause of death and disability in the United States includes heart disease and vascular disease 2 million people diagnosed with an ACS/yr 1.5 million will experience an acute MI Of these, 0.5 million will die Almost half of these (250,000) will be sudden and within the first hour of onset of symptoms 500,000 people will suffer a stroke each year in the US Nearly 1/4 of these will die

4. Cardiovascular Disease

5. Cardiovascular Disease Atherosclerosis plaque accumulation within the lumen of the artery resulting in decreased lumen inner diameter increased vascular resistance potential for thrombus or embolus formation associated with HTN Stroke Angina, Heart Attack Renal Failure

6. Cardiovascular Disease Risk Factors Age Family History Hypertension Hypercholesterolemia Male gender Smoking Diabetes Contributing Risk Factors Diet Obesity Oral contraceptives Sedentary living Personality type

7. EMS System Role The original Paramedic idea was based upon the need for rapid response to, identification of and emergency care for victims of: Sudden Cardiac Death (SCD) Acute Myocardial Infarction (AMI)

8. EMS System Role The EMT and Paramedic roles in the treatment of sudden cardiac death have been proven to make a difference in survival Contributions being recognized in acute coronary syndromes Key is a STRONG chain of survival

9. EMS System Role Weak vs. Strong Chain of Survival

10. Anatomy & Physiology

11. Anatomy Review

12. Anatomy Review

13. Blood Flow

14. Cardiac Cycle

15. Cardiac Output Stroke volume x Heart rate Also dependent upon Stroke volume contractility preload volume in ventricle at end of diastole afterload resistance against which left ventricle must pump Starling’s law

16. Vascular System Aorta ascending thoracic descending thoracic abdominal Vena cava superior inferior

17. Peripheral Vascular System Arteries & Veins 3 layers tunica media > in arteries flow through a vessel directly proportional to the fourth power of the radius atherosclerosis vascular constriction

18. Peripheral Vascular System Venous Return Skeletal muscle pump Muscular contraction squeezes adjacent veins causing a milking action Valves prevent opposite flow Respiratory Movements Diaphragm contraction exerts pressure in abdomen and decrease pressure in thoracic cavity Blood moves to area of lower pressure in thorax

19. Peripheral Vascular System Venous Return Constriction of veins Sympathetic stimulation causes contraction of the smooth muscle walls of veins Gravity

20. Peripheral Vascular System

21. Peripheral Vascular System

22. Peripheral Vascular System Negative Effects on Venous Return Increasd intrathoracic pressure PEEP/CPAP/BiPAP

23. Peripheral Vascular System Arterial Resistance (afterload) BP cardiac output x systemic vascular resistance (stroke volume x heart rate) x systemic vascular resistance Systemic vascular resistance vasoconstriction Sympathetic NS effects Medications (prescription, non-prescription, recreational) Renin-Angiotensin-Aldosterone mechanisms atherosclerosis

24. Coronary Circulation Usually thought of as 3 arteries Left (Main) Coronary Artery Left circumflex artery Left anterior descending artery Right Coronary Artery Areas affected

25. Coronary Circulation Coronary Sinus short trunk receiving blood from cardiac veins empties into the right atrium between inferior vena cava and AV orifice Cardiac veins feed into the coronary sinus

26. Electrophysiology

27. Electrical Conduction System Sinoatrial Node (Sinus Node or SA Node) “Normal pacemaker” of the heart Internodal Atrial Pathways Atrioventricular Junction (AV junction) AV node “Gatekeeper” slows conduction to the ventricles allowing time for ventricles to fill Bundle of His

28. Electrical Conduction System His-Purkinje System Bundle Branches Right bundle branch Left bundle branch left anterior fascicle left posterior fascicle

29. Electrical Conduction System

30. Electrical Conduction System Myocardial Cells Characteristics automaticity: cells can depolarize without any impulse from outside source (self-excitation) excitability: cells can respond to an electrical stimulus conductivity: cells can propagate the electrical impulse from cell to another contractility: the specialized ability of the cardiac muscle cells to contract

31. Electrical Conduction System Myocardial Cells Three groups of cardiac muscle Atrial Ventricular Excitatory/Conductive Fibers Atria contract from superior to inferior Ventricles contract from inferior to superior Atria and Ventricles separated Conduction from atria to ventricles only through AV bundle “All or None” principle of muscle function

32. Electrophysiology Electrolytes Allow for electrical and mechanical function of heart Sodium: major extracellular cation, role in depolarization Potassium: major intracellular cation, role in repolarization Calcium: intracellular cation, role in depolarization and myocardial contraction Chloride: extracellular anion Magnesium: intracellular cation

33. Electrophysiology Depolarization Reversal of charges at the cell membrane (opposite charge from resting state) Resting Potential more intracellular negatively charged anions than extracellular approximately -90 mV in myocardial cell Action Potential stimulus to myocardial cell allows sodium to enter cell changing to positive intracellular charge approximately +20 mV in myocardial cell slow influx of Calcium follows

34. Electrophysiology Depolarization Complete depolarization normally results in muscle contraction Threshold minimal stimulus required to produce excitation of myocardial cells

35. Electrophysiology Repolarization Process of returning to resting potential state Sodium influx stops and potassium leaves cell Sodium pumped to outside the cell Relative refractory period cell will respond to a second action potential but the action potential must be stronger than usual Absolute refractory period cell will not respond to a repeated action potential regardless of how strong it is

36. Electrophysiology

37. Electrophysiology

38. Electrophysiology Depolarization causes Ca2+ to be released from storage sites in cell. Ca2+ release causes contraction.

39. Electrophysiology

40. Electrophysiology

41. Cardiac Conduction Cycle

42. Electrophysiology Pacemaker Sites of the Heart & Intrinsic Firing Rates Specialized groups of cells called pacemaker sites SA Node 60 to 100 bpm AV Junction 40 to 60 bpm Ventricles 20 to 40 bpm

43. Electrophysiology

44. Electrophysiology

45. Electrophysiology

46. Electrophysiology Electrical impulse from depolarizing pacemaker cell spreads to working myocardial cells and stimulates them.

47. Electrophysiology The SA Node is the heart’s primary pacemaker WHY?

48. Electrophysiology If the SA Node does not fire, what site will take over? What will happen to the heart rate?

49. Electrophysiology Ectopic Impulse Formation Enhanced Automaticity Pacemaker cells lost function of contractility acquired function of impulse formation May lead to ectopic (extra) beats Reentry abnormal wavefront propagation “electrical loop” accessory pathway

50. Effects of ANS on Electrophysiology Medulla Carotid Sinus and Baroreceptors Parasympathetic Nervous System Acetylcholine Cholinesterase Sympathetic Nervous System Alpha Beta Inotropic effect Dromotropic effect Chronotropic effect

51. Electrophysiology: Results of Depolarization & Repolarization