1. Cardiac Anatomy 101 Julianne Koehler, MS, RN, CCRN Nurse Educator
The Children’s Hospital Heart Institute

2. Layers of the heart
The pericardium is the fluid filled sac that surrounds the heart.

3. Pericardium The pericardium has several functions.
It keeps the heart contained in the chest cavity.
The pericardium also prevents the heart from over expanding when blood volume increases.
The pericardial cavity is filled with fluid which reduces friction between the pericardial membranes.

4. Myocardium
Myocardium is the muscular middle layer of the wall of the heart.
It is composed of spontaneously contracting cardiac muscle fibers which allow the heart to contract.

5. Endocardium The lining of the interior surface of the heart chambers.
The endocardium consists of a layer of endothelial cells and an underlying layer of connective tissue.

8. ATRIUM- is a chamber that pumps blood into the heart.
VENTRICLE- is a chamber that pumps blood out of the heart.
The atria and ventricles regulate blood flow into and out of the heart.

9. Heart Chambers
The atria are low pressure chambers which receive blood into the heart.
The ventricles are high pressure chambers responsible for ejecting blood out of the heart.
The right and left side of the heart are separated by a wall called a septum.
The LV is much thicker than the RV due to the demand of pumping blood systemically.

10. Valves There are four valves in the heart.
These valves are one way to ensure blood flow in the correct direction.
They prevent blood flow from backing up into the chamber it has just left.

11. Atrial-Ventricular Valves
A-V valves separate the atria and the ventricles.
The tricuspid valve separates the right atrium from the right ventricle.
The mitral valve separates the left atrium from the left ventricle.
REMEMBER TO “ TRY TO BE RIGHT”
The tricuspid valve has three leaflets; the mitral valve has two leaflets.

12. Outflow valves
The aortic valve is on the base of the left ventricular outflow track (LVOT).
The pulmonic or pulmonary valve is at the base of the right ventricular outflow track (RVOT).
These valves are also called semilunar valves.

13. Great Arteries
The Aorta is the great artery that delivers red, oxygenated blood to the body and organs for oxygen consumption.
The Pulmonary artery delivers blue, deoxygenated blood to the lungs so that it can become re-oxygenated.

14. The atrial chambers fill with blood from the IVC and SVC.
Then, the atria contract and fill the ventricles with blood. This is known as diastole. The pressure in the atria must then be relatively low in order to adequately fill.
Next the A-V valves close. This is known as S1 when assessing heart tones.
Then the ventricles contract and blood is ejected to the lungs (PA) and body (Ao).
The semilunar valves close. This is S2 when assessing heart tones. 14

15. Cardiac Cycle

16. Conduction
In order for the cardiac cycle to take place, you need ELECTRICITY.
The normal conduction pathway in the heart consists of an electrical chain of command.
The Sinoatrial node or SA node is the commander in chief of conduction. This is the pacemaker of the heart.

17. Cardiac Conduction

18. Conduction The SA node is like an attending MD in charge.
The AV node is like one of our fellows. Pretty good in a pinch, but you’d rather have an attending.
The Bundle of His is like a resident. Better than nothing, but not really getting the job done.
The Purkinje fibers are like a medical student, and at that point you might as well give up.

19. EKG waves
The P wave represents the spread of electrical activity over the atrium.
The normal depolarization begins at the sinoatrial (SA) node near the top of the atrium.

20. EKG waves
The PR interval is the time from the beginning of the P wave until the beginning of the QRS complex.
The PR interval may be prolonged when conduction of the electrical wave through the AV node is slow. This may be seen with degenerative disease of the node, or with digoxin, hyperkalemia, hypercalcemia, or hypothermia.

21. EKG waves
The QRS complex represents activation of the ventricle. Special conducting bundles spread the wave of depolarization rapidly over the ventricle.

22. EKG waves
The ST segment is the portion of the tracing falling between the QRS complex and the T wave. During this time, the ventricle is contracting, but no electricity is flowing. The ST segment is therefore usually even with the baseline.
The T wave represents the wave of repolarization, as the ventricle prepares to fire again.

23. Conduction
In the event that the SA node is impaired, say due to inflammation from surgery, the AV node takes over.

24. The AV node, is however not an ideal pacemaker for kids.
What is the big deal?
The AV node, is however not an ideal pacemaker for kids.
WHY?

25. Conduction & Cardiac Output
What is cardiac output?
Heart rate x stroke volume.
What is stroke volume?
Each contraction of the heart results in an ejection of blood termed the stroke volume.

26. What is ejection fraction?
The amount of blood pumped per contraction compared to the maximum left ventricular volume prior to contraction is the ejection fraction, which is a measure of the effectiveness of the heart as a pump.
So, if your LV fills 80cc’s and ejects 40cc’s what is your EF?
What is normal EF?

27. Conduction
Children, due to their size cannot really alter their SV, so their cardiac output is HR dependent.
This is why a SR and adequate HR is so important in children.

28. Conduction
As the atria contract, the blood pressure in each atrium increases, forcing additional blood into the ventricles. The additional flow of blood is called atrial kick.
You need normal conduction to maintain your atrial kick.

29. Let’s talk definitions
PRELOAD, what is it?
Preload is the end-diastolic volume (EDV) at the beginning of systole.
Why do we like to decrease preload in our patient population?

30. Preload applied
So, if your CVP is high, what does this do to your preload?
What medications might lower your preload?

31. Contractility
Contractility:  Contractility is the intrinsic ability of cardiac muscle to develop force for a given muscle length.  It is also referred to as inotropism.
How can you increase a patient’s contractility?

32. Contractility Digoxin Inotropes Vasopressors Beta-blockers
Ace Inhibitors

33. Afterload
Afterload:  Afterload is the tension (or the arterial pressure) against which the ventricle must contract.  If arterial pressure increases, afterload also increases.
Afterload for the left ventricle is determined by aortic pressure, afterload for the right ventricle is determined by pulmonary artery pressure.

34. Afterload
What are some medications that decrease afterload?

35. Medications that decrease afterload.
Milrinone
Anti-hypertensives
Sedatives
Analgesics
Paralytics
Diuretics

36. Jeopardy question
What is the ultimate afterload reducer?

37. Let’s talk flow
Right Side of the Heart The blood coming from the body to the heart collects in the Right Atrium, filling it up. This initiates a contraction of the walls of the Right Atrium forcing the Tricuspid Valve to open as the blood gushes to the Right Ventricle.

38. Flow
The Right Ventricle fills with blood which forces the Tricuspid Valve to close and initiates the muscle of the Right Ventricle to contract, open the Pulmonic Valve and squeeze the blood through the Pulmonic Valve and on to the lungs.

39. Flow, baby flow
This blood will replenish itself with more oxygen and get rid of the carbon dioxide and return to the left side of the heart to begin another cycle.

40. More flow
Left Side of the Heart The blood coming from the lungs to the heart collects in the Left Atrium, filling it up. This initiates a contraction of the walls of the Left Atrium forcing the Mitral Valve to open as the blood gushes into the Left Ventricle.

41. Flow
The Left Ventricle fills with blood which forces the Mitral Valve to close and initiates the muscle of the Left Ventricle to contract, open the Aortic Valve, and squeeze the blood through the Aortic Valve and on to the body.

42. Flow
The blood coming out of the Left Ventricle to the Aorta is under high pressure. This pressure is enough to rush it to the different parts of the body at high velocity and give its oxygen and nutrients to the body tissues. The blood comes back from the body to the right side of the heart.

43. Are we done flowing?

44. Little, but oh so important! Coronary circulation

45. Coronary arteries
The coronary arteries are classified as "end circulation", since they represent the only source of blood supply to the myocardium: there is very little redundant blood supply, which is why blockage of these vessels can be so critical.

46. Coronary variations

47. Coronary arteries
Two major coronary arteries branch off from the aorta near the point where the aorta and the left ventricle meet:
The right coronary artery (RCA) which supplies the right atrium and right ventricle. It branches into the posterior descending artery which supplies the bottom portion of the left ventricle and back of the septum.

48. Coronary arteries The left main coronary artery branches into:
the left anterior descending artery (LAD), which supplies the front and bottom of the left ventricle and the front of the septum
the circumflex artery, which supplies blood to the left atrium, side and back of the left ventricle

49. Coronary arteries

50. Coronary Veins
The coronary veins drain deoxygenated blood from the heart muscle into the coronary sinus.
So what do you think the oxygen saturation is in the RA?

51. Collaterals
Collateral circulation is a network of tiny blood vessels and under normal conditions not open…

52. Jeopardy question
At what phase of the cardiac cycle are the coronary arteries perfused?

53. Dedicated to Maggie Cavanaugh
Any Questions?
Dedicated to Maggie Cavanaugh
Any Questions?