MEDS 320 Lecture 5 - Habib PDF

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Habib...

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Cardiopulmonary anatomy pt. 2 ● pericardial sinuses → important for where fluid can build up and signs of trauma ○ don’t need to know the names ○ next slide → posterior view of the heart ● left side of the heart → really posterior → most visible from the posterior view ● left pulmonary artery → it’s a lazy y fork not a t ● coronary sinus → usually big purple, hard in structure → venous structure and it’s full of clotted blood ○ collecting point for most of the venous blood coming from heart tissue itself ○ this then drains into the right atrium ■ right atrium → 3 structures that drain into it ● superior vena cava ● inferior vena cava ● coronary sinus ● anterior view ○ great cardiac vein & left anterior descending (LAD) → separates the left ventricle from right ventricle ■ will be responsible for the 3 letter codes ■ LAD → also known as the widowmaker → because occlusion of this are responsible for most of the lethal heart attacks ○ right coronary artery (RCA) → separates the right atrium from the right ventricle ● Posterior view ○ posterior descending artery (PDA) → separates the left ventricle from the right ventricle on the posterior side of the heart ■ branch of the right coronary artery in most people ● will be responsible for multiple variations

● sometimes it can come off the left → then the right isn’t feeding much of the heart ■ few known variations of the coronary artery distribution → changes the risk of death from heart problems ■ variations are very common → 80% have different ones → the variations increase the risk for heart problems ■ can determine it with an angiogram → injection of contrast into the vessels and then image it ● primary variation is in branching pattern → usually in the PDA ○ left circumflex artery (LCX) ■ one of the few cases that there is a left/right → doesn’t mean that there’s a right ■ there is no right ● could be a right circumflex → but wouldn’t have both a right and a left → would be instead ■ could come off the right coronary artery → unusual variation ● Internal anatomy of the heart ○ right atrium → right ventricle → lungs → left atrium → left ventricle ■ need to be able to do a blood loop starting or ending in any other area ○ right atrium ■ 3 openings into the right atrium and one exit ● fetal has 2 outflow ● sometimes the adult the second one might be a little still open ■ pectinate muscles → ridges on the wall ● some in the left atrium but not many ■ terminal crust → transition from the rough portion to the smooth portion

● care about this because if you follow where it meets the superior vena cava → find the beginning of the SA Node ■ 3 inflows → superior vena cava, inferior vena cava, coronary sinus ■ outflow → tricuspid valve ■ fossa ovalis → the hole that fetus still have ● blood runs from the right atrium to the left atrium → immediately to the left ventricle ● immediately begins to seal after they took their first breath ● patent foramen ovalis → it’s still open → PFO ○ might be suspected after a. stroke ○ because it might tear up some of the cells that come through → stimulates some platelets → causes a clot ○ Blue kid → big pfo ○ patent means open → same as a patent in law → need to be open about how you made it ○ go through tricuspid → Right ventricle ■ AV valves → strange ● muscles are attached to the valve → they do not close or open the valve ● they keep the valve closed after pressure from the passing blood has already closed them ● atria contract → push blood into the ventricles → then the ventricles contract while the atria dilate → blood starts to go out in any direction it can ○ ventricles swing back when blood rushes back → the papillary muscles hold the door closed

● prevents prolapsing → results from the failure of the papillary muscles ○ some of the blood will go back in to the atrium from which it came → will cause parts of the valve to vibrate → heart murmur ○ mitral valve prolapse → right valve isn’t closing properly ○ lots of causes of murmurs ■ also have ridges in the wall → trabeculae carneae ● bridges of muscles ethan come out of the wall → criss cross → form mesh work ● more efficient because the heart doesn’t beat the way it’s diagramed → they twist ○ also why the AV valves have a tendency to come open ○ Left Atrium ■ thinnest wall chamber ● compared to the left ventricle that has the thickest wall chamber ■ blood gets a lot of gravity assist → can fall from the left atrium to the left ventricle ● left atrium only does stuff really when you do exercise ■ small auricle on the right, big on the left → look kinda like a dog ear ● always fold anteriorly → can use the direction they are folded to find the front side of the heart ■ mitral valve → Left AV valve (rarely called bicuspid) ○ LEft Ventricle ■ V similar to the right ventricle ■ papillary muscles → hold it close ■ semilunar valves → goes to aorta ○ semilunar valves

■ one for the pulmonary artery and one for the ascending aorta ■ anytime you exit a ventricle ■ kinda like shirt pockets ■ blood comes up → pushes it against the wall ■ blood falls down → fills the pocket ■ they meet in the middle and just stop ■ can tell difference between the aortic or pulmonary ● aortic → has 2 openings ● into the coronary arteries ● coronary arteries → emerge from the coronary semilunar valves ● systole → chamber is contracted ● diastole → chamber is relaxed ○ atrial and ventricular are out of phase ○ sys/dias → understood that you’re talking about the ventricles ● arteries at highest pressure → at systolic ○ valves are open → openings of the semilunar valves → covering the openings to the coronary artery ○ left and right coronary arteries → pressurized during ventricular diastole ■ out of phase with the rest of the arteries ● Cardiac skeleton ○ valves → held in place by rings of fibrocartilage ■ interconnected by bands of fibrocartilage ○ together known as the cardiac skeleton ○ primary function → stabilize the valves ○ secondary function → give an anchor to twist on ○ third function → only part of the heart through which an action potential will not propagate

■ where conduction system passes through it → silent moment → known as the Av bundle ● this creates the offset between the systolic and diastolic phases ● aka between the atria and the ventricles ○ possible to have deficits → can cause problems ● coronary vessels ○ branching patterns ○ hitting the major ones ○ most common pattern → 2 coronary arteries ■ left and right → both very large in diameter ■ balanced distribution: ● technically right dominant ● pda usually does a little more than half of the septum ● only does a little more than half ■ left → LCA ● short ● splits into two parts ● ends as the LAD and the LCX ● LAD → descends on the anterior side of the heart → feeding a good portion of both ventricles → descends in the groove between the two ventricles ● LCX → bends around the hearts and wraps around between the left atrium and left ventricle and serves the posterior of the heart ○ ends near the PDA ■ right → RCA ● does the circumflex ● runs in a groove between r atrium and r ventricle ● wraps around to the posterior → throws down a posterior descending ● gives rise to the PDA

○ 20% in general, more in patient population with cardiac symptoms ■ more risky ■ left dominant coronary artery ● pda → comes off the left circumflex ● lcx nodal comes off the lda ● entire septum is coming from the left pda ● 70% of the heart tissue by mass is being fed by the left coronary artery and it’s branches ● leads to a smaller right coronary artery → much smaller in diameter → easier for it to become occluded ● left coronary artery → usually very large ○ if it becomes occluded → it affects a much larger part of the heart ○ more likely to be lethal ● higher risk scenario than a balanced distribution ○ in either case → couple places where the left and right side do communicate via anastomosis ■ LCX to RCA ■ PDA to LAD ● in right dominant → both of these are between a right and left sided vessel ● in left dominant → only the LCX to RCA connects the two sides ● both very useful in allowing blood to reach all areas of the heart ● even with partial or complete occlusion of coronary artery ○ rescues not as effective in a left dominant ■ PDA to LAD in right dominant → is between a right sided and left sided heart

■ in left dominant → LAD and PDA → both left → left to left ● Coronary veins ○ 3 big named veins ■ great ● alongside the LAD and part of the LCX ■ middle ● goes with the PDA ■ small ● along the right edge of the heart ● with right marginal ● Conduction systems...