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Translating Chapter 36

Translating Chapter 36. Carolyn E. Matthews RN, MSN Spring 2009 1. Atrium & Ventricle Page 676.

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Translating Chapter 36

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  1. Translating Chapter 36 Carolyn E. Matthews RN, MSN Spring 20091

  2. Atrium & Ventricle Page 676 • Atrium: Think about the atrium in a hotel – where you check in and wait to be shown to a room. Blood ‘checks in’ to the R atrium after traveling through the body and to the L atrium after traveling through the lungs. Carolyn E. Matthews RN, MSN

  3. Ventricle Page 676 • Ventricle: When you ‘vent’ about something, you let it all out. The ventricles let the blood out – the R ventricle to the lungs, the L ventricle to the body. Carolyn E. Matthews RN, MSN

  4. Ventricle • The L ventricle is the most muscular part of the heart. Since sending oxygenated blood to the body is the most important job of the heart it needs extra muscle power. Carolyn E. Matthews RN, MSN

  5. MAP page 677 • “mean arterial pressure  (MAP) the average pressure within an artery over a complete cycle of one heartbeat” • http://medical dictionary.thefreedictionary.com/Mean+arterial+pressure • This pressure has to be at least 60mm Hg in order to flow through the arteries well enough to ‘feed the heart’ (coronary arteries) and for adequate perfusion of major organs. Carolyn E. Matthews RN, MSN

  6. Perfusion defined • Perfusion has to do with how well all of the cells and organs are drenched with blood and it is delivering (i.e. oxygen) which is necessary for life. • From Latin: meaning to pour throughout http://dictionary.reference.com/browse/perfusion Carolyn E. Matthews RN, MSN

  7. The electrical system of the heart (page 679) • The electrical impulses that create the contractions (hence the HR) travel just the way the heart lies in the body Carolyn E. Matthews RN, MSN

  8. Sinoatrial node • SA is the body’s natural pacemaker. He is the CEO of the pulse company. The ‘sino’ means a sinus. SA’s office is situated in a sinus within the atrium, where the superior vena cava meets the R atrium. Carolyn E. Matthews RN, MSN

  9. The AV node • His office is located where the Right atrium and R ventricle meet. He is the pulse supervisor. He sends messages to various parts of the heart regarding when to constrict. There is a slight delay when he gets orders from the SA node while he decides on pulse assignments. Carolyn E. Matthews RN, MSN

  10. The supervisor has HIS bundle of managers that travel from him to tell muscles further down what to do. They branch off – some go right and some go left to tell the ventricles what to do. At the bottom of the chain of command are the Purkinjes. Carolyn E. Matthews RN, MSN

  11. The way SA got to be CEO… • The SA node can make the heart beat (constrict) 60 – 100 times a minute, which is what the body likes. • The AV node can try to take over, but he can only manage 40 – 60 BPM and the Purkinje fibers can only muster up 20 – 40 BPM. • Only the SA node has enough power to give the body the blood output that it wants, so he was hired as CEO. Carolyn E. Matthews RN, MSN

  12. Blood pressure (page 682) • Pressure in the vessels goes down as the blood makes it’s circle from L ventricle to R atrium. Pressure in the large arteries, just out of the ventricle is 80 – 100 mm Hg. In the veins, the pressure is a lot lower and keeps dropping until by the time the blood gets to the R atrium it is 0 – 5 mm Hg. Carolyn E. Matthews RN, MSN

  13. Dependent edemapage 683 • The drop in pressure within the blood vessels on the venous side of the system is one reason why a person with a compromised system will have swelling in their feet – the blood manages to get to the feet using gravity to help, but then if the pressure is too low the veins can’t seem to get the blood to go back up the legs. Then fluid seeps out of the capillaries into the interstitial space while the blood is waiting to get moving. Carolyn E. Matthews RN, MSN

  14. Diastole: the ventricles relax and let the atrium send more blood in. This doesn’t take much work, so the pressure is not as high. Systole: the ventricles contract to push the blood out. This requires more work (pressure). Blood pressure Carolyn E. Matthews RN, MSN

  15. At the end of Diastole: The ventricles are full of blood, ready to be pushed out. Preload Carolyn E. Matthews RN, MSN

  16. Preload (page 680) • As the ventricles fill up, the muscles have to stretch so it all will fit in. That is the preload – how much the muscle fibers are stretched right before they contract to push the blood out. Carolyn E. Matthews RN, MSN

  17. Preload is important because Dr. Ernest Starling ( a British physiologist, 1866 -1927) made a law that says the more the heart has to stretch when being filled – the more forcefully it contracts. www.britannica.com/.../563670/32902/Starling Preload (page 681) Carolyn E. Matthews RN, MSN

  18. Afterload (page 681) • This is the resistance the heart has to overcome in order to eject the blood through the semilunar valves and into the peripheral vessels. Carolyn E. Matthews RN, MSN

  19. The circulatory system has blood present in all vessels all the time. So, when the ventricles push the blood into the aorta and pulmonary artery it has to push the blood into ‘pipes’ that are already full. That’s why it takes 100-120 mmHg to push the blood out. Afterload Carolyn E. Matthews RN, MSN

  20. Why afterload could matter: • If the ‘pipes’ are clogged (for example -thickened blood) or narrowed (arteries constricted) or too full (hypervolemia) it takes even more work (pressure) to push the blood out of the ventricles --- BP elevates. Carolyn E. Matthews RN, MSN

  21. Blood pressure (page 691) • Normal BP is systolic <120 and diastolic <80. • There is usually a difference between the two of 30 – 40 mm Hg. (120 – 80 = 40). • That difference is called the pulse pressure. • If the pulse pressure is < 30 or >40…that is a noteworthy sign of cardiac problems. Carolyn E. Matthews RN, MSN

  22. Blood pressure (page 690) • The text defines hypertension (high blood pressure) as a BP > 140/90. • Prehypertension – BP readings that fall between the normal 120/80 and hypertensive140/90. Carolyn E. Matthews RN, MSN

  23. Hypotension • BP < 90/60 mm HG doesn’t help the blood deliver sufficient nutrition to the cells. Carolyn E. Matthews RN, MSN

  24. The heart takes advantage of gravity to help it get blood down to the feet. If you are lying (supine) your BP has to be a little higher. So if you sit up, gravity helps a little so the BP may drop a bit. Postural hypotension Carolyn E. Matthews RN, MSN

  25. Postural hypotension (page 691) • But, if you stand up quickly - now gravity lets the blood drop to the periphery. And the systolic pressure might drop as much as 20 mm Hg and the diastolic 10 mm Hg –This drastic drop can make you dizzy or even faint. Carolyn E. Matthews RN, MSN

  26. Stroke volume • A stroke of a paddle pushes water and propels the boat. The heart’s stroke volume is the amount of blood pushed out of the heart by the L ventricle during systole. Carolyn E. Matthews RN, MSN

  27. If you multiply the stroke volume(The normal stroke volume index: 40-50 mL per contraction per square meter BSA) by how many strokes the heart makes in a minute (HR) you have the cardiac output. Carolyn E. Matthews RN, MSN

  28. Cardiac output = heart rate X stroke volume(page 680) • The cardiac output tells you how much blood the heart pushes out into the body per minute. (How efficient it is) • A healthy heart under normal conditions puts out 4-7L per minute. Carolyn E. Matthews RN, MSN

  29. Cardiac output • And it also shows how well the blood is being “poured throughout” – i.e. whether the cells and organs are getting adequate perfusion. Carolyn E. Matthews RN, MSN

  30. Controlling the C-V system (page 682-683) • The heart rate, blood volume, and openness of blood vessels are changed to fit the body’s need. These affect the rate, rhythm and BP. Those in turn affect the cardiac output. Carolyn E. Matthews RN, MSN

  31. Chemoreceptors • These guys are in charge of checking the blood chemistry, especially oxygen levels for the heart. Carolyn E. Matthews RN, MSN

  32. Baroreceptors • These guys are in charge of checking on blood volume. They do this by measuring how full the blood vessels are. Carolyn E. Matthews RN, MSN

  33. The chemoreceptors and the baroreceptors report their findings to the guys like the Autonomic Nervous System and the Hypothalamus. Carolyn E. Matthews RN, MSN

  34. Autonomic Nervous System Based on the reports from the receptors, the ANS sends out neurotransmitters that talk the SA node into changing heart rate or the blood vessels into constricting or relaxing. Like histamines that cause vasodilation. Or kinins that not only dilate blood vessels but make the capillaries more permeable. Carolyn E. Matthews RN, MSN

  35. Kidneys • Based upon the receptors’ reports the kidneys may release Renin which becomes Angiotensin I. • Angiotensin I visits the lungs, where ACE lives. ACE convinces Angiotensin I to reinvent himself as Angiotensin II or III. • The new Angi tells aldosterone to do his thing – which is to hold onto Na++. Water always hangs out with Na++, so if there is more sodium there will be more water in the bloodstream. Carolyn E. Matthews RN, MSN

  36. Endocrine System • The endocrine system gets involved because the hypothalamus receives reports and might tell the pituitary gland to send ADH to talk to the kidney. • ADH tells the kidney to hold onto water. More water means more blood volume. Carolyn E. Matthews RN, MSN

  37. Cardiovascular assessment (page 692) • You hear Bruits, you feel thrills. • They are caused by turbulence in the vessel. Carolyn E. Matthews RN, MSN

  38. Cardiovascular assessment - Apex • Apex means Point. • The apex of the heart is at the bottom where it is pointed – that’s where the apical pulse is found. • FYI – the apex of the lungs are the points up by your neck. Carolyn E. Matthews RN, MSN

  39. C-V assessment (page 692) • Palpation is feeling with your fingers and palm. • This not to be confused with palpitations (page 688) – which are when you feel your heart flutter because of a momentary rhythm disturbance. Carolyn E. Matthews RN, MSN

  40. C-V assessment (page 687) • See table 36-1 for different types of chest pain. • Listen carefully to client’s description of pain…it can assist proper diagnosis. Ask more than the one question – “Where does it hurt?” Ask several questions to find quality, severity, location, radiation, duration and relieving factors. Carolyn E. Matthews RN, MSN

  41. C-V assessment (page 689) • Veins are not really blue, like the book illustrations. But, the nail beds, mucosa and skin can have a bluish hue if the hemoglobin doesn’t have any oxygen. The oxygen mixed with the iron make the red color. Carolyn E. Matthews RN, MSN

  42. C-V assessment • People who have chronic low blood levels of oxygen look gray. The proper term is ashen which is not to be confused with dry flaky ashy skin. Carolyn E. Matthews RN, MSN

  43. C-V assessment • Clubbing – The tips of the fingers of people who have chronic low blood levels think that if they flatten out it’ll be easier for them to get oxygen. Carolyn E. Matthews RN, MSN

  44. C-V assessment - edema • Edema is a sign that something is wrong with the system. The fluids can leave the capillaries but for some reason are not getting back into the vessels. Carolyn E. Matthews RN, MSN

  45. Edema • Example: You are driving on I-4. Histamine has signs that say he’s selling gasoline for 50¢ a gallon (making capillaries more permeable). So, naturally you leave I-4 and go to the gas station. But, then when you drive onto the on-ramp you cannot get back onto the highway. Maybe there is traffic congestion (increased blood viscosity) or one lane is blocked off (blood vessels have constricted) or it’s full (hypervolemia). In the meantime, other cars are piling up behind you waiting to get back onto I-4 also (the edema gets worse). Carolyn E. Matthews RN, MSN

  46. Laboratory values – Cardiac markers (page 694-696) • Troponin – a protein released if the cardiac muscle is damaged. Not found in healthy clients. • CK-MB is an enzyme found only in the heart. If it is activated, that implies an MI has occurred. Carolyn E. Matthews RN, MSN

  47. Laboratory values – Cardiac markers (page 694-696) • Myoglobin – a protein that appears if there is muscle damage. It is found in skeletal muscle too…so other s & sx are needed for dx of MI. Carolyn E. Matthews RN, MSN

  48. Laboratory values (page 694-696) • Lipids – total serum cholesterol >200 increases risk of coronary artery disease. www.cdc.gov/.../basics/cholesterol.htm You want your LDH to be Low and your HDH to be High. Carolyn E. Matthews RN, MSN

  49. NCLEX pointers (page 705) • Learn the normal changes in the C-V system due to aging (Chart 36-1). • Diagnostic imaging often uses iodine based contrasts – check for allergies! • Needle insertion sites for tests like cardiac catheterization can bleed or develop hematomas – watch them carefully! Carolyn E. Matthews RN, MSN

  50. NCLEX pointers (page 705) • Denial is common. • Be aware of and teach people about the risk factors for heart disease and what they can do the lower risks. Carolyn E. Matthews RN, MSN

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