Term
| what is an aneurysm? what can cause it? |
|
Definition
| an abnormal *dilation of the arteries or veins that develops where there is a weakening of the vessel wall. it can be caused by congenital defects (marfan syndrome), infections (vasculitis, acute inflammatory rxn), trauma (car accidents) and systemic diseases |
|
|
Term
| where are the most common atherosclerotic aneurysms? why? |
|
Definition
| in the abdominal aorta below the renal arteries. pressure and turbulence here is significant, especially where it bifurcates into the illiacs |
|
|
Term
| how would an atherosclerotic aneurysm start in the abodominal aorta? |
|
Definition
| swelling of the vessel, followed by weakness of the vessel wall due to atherosclerosis (infiltration of inflammatory cells, cholesterol, intima integrity impairment, and calcium deposition), often followed by thrombus formation - which can break off and embolize into systemic circulation |
|
|
Term
| if the superimposed thrombus on the atherosclerotic lesion breaks off, what can happen? |
|
Definition
| portions can break off and embolize into systemic circulation, possibly leading to a stroke in the brain, ischemic bowel in the mesenteric vasculature, gangrene in the lower extremities, and impaired renal function if in the renal arteries due to occlusion in any of these areas |
|
|
Term
| is it a common thing for elderly pts to have atherosclerotic aneurysms? |
|
Definition
|
|
Term
| can you palpate the abdominal aorta in a physical exam? if it is enlarged, should it be surgically repaired? |
|
Definition
| yes, but if it is enlarged, you don't want to palpate too much. if it is enlarged, it doesn't necessarily have to be surgically enlarged - the size and the pt's comorbidities need to be evaluated |
|
|
Term
| how might an elderly person present with abdominal aneurysms? |
|
Definition
| the abdominal aorta is right next to the lumbar vertebrae, so they may present with lower back pain or compression fractures if the vessels there are stenotic or occluded |
|
|
Term
| what is a basic guideline in terms of size for determining whether an aneurysm will rupture? |
|
Definition
| aneurysms greater than 6cm are likely to rupure |
|
|
Term
| how would an atherosclerotic aneurysm present on a physical exam? |
|
Definition
| as a pulsatile mass that may or may not be noticeable, bruits may also be audible |
|
|
Term
| how can you tell a post-mortum thrombus from an ante-mortum thrombus? |
|
Definition
| lines of zahn, which are present in an ante-mortum blood clot. this appears as platelets and RBCs lying down in an organized fashion |
|
|
Term
| what causes syphilitic aortitis? |
|
Definition
| tertiary syphilis (pts w/syphilis for a number of years) |
|
|
Term
| where does syphilitic aortitis affect? |
|
Definition
| usually the *thoracic portion of the aorta, involving the ascending and transverse portions |
|
|
Term
| how does syphilitic aortitis work? |
|
Definition
| the vasa vasorum (O2 supply to aortic media) is narrowed, and the media loses its elastic support - ultimately dialates, which can lead to tears and ruptures |
|
|
Term
| what is syphilitic aortitis characterized by? |
|
Definition
| "tree barking" or longitudinal wrinkling of the intima |
|
|
Term
| can there be secondary atherosclerotic involvement with syphilitic aortitis? |
|
Definition
| yes, if it proceeds proximally, there may be incompetence of the aortic valve (difficulty opening), causing the ventricle to work harder to pump blood through the impaired aortic valve, leading to hypertrophy (secondary LVH) |
|
|
Term
| what are possible signs and symptoms of syphilitic aortitis due to its specific location? |
|
Definition
| there may be swallowing difficulties (dysphagia), recurrent laryngeal nerve encroachment (dry unproductive coughing), breathing problems, bone erosion (upper back, neck pain - though more likely in lumbar vertebrae), and cardiac disease (may present with a murmur) |
|
|
Term
| how common is it for aortic dissections to have atherosclerotic changes present? |
|
Definition
| commonly, aortic dissections will not have atherosclerotic changes or only minimal changes present |
|
|
Term
| what age group are aortic dissections more common in? |
|
Definition
|
|
Term
| what co-morbidity are aortic dissections usually associated with? |
|
Definition
|
|
Term
| how do aortic dissections work? |
|
Definition
| aortic dissections usually originate with intimal tears, where blood enters and dissects the wall. this may form 2 lumens, forming a double-barreled aorta, which can hemorrhage back into the original aortic lumen (higher survival rate w/this). if the dissection occurs through the adventitia, this can result in a catastrophe w/high mortality |
|
|
Term
| where do aortic dissections usually happen? what if it happens close to the aortic valve? the pericardium? |
|
Definition
| within 10 cm of the aortic valve. if it is proximal to the aortic valve, valve insufficiency may result or if the dissection occurs into the pericardium, it can cause enough pressure to stop the heart from beating - mortality |
|
|
Term
| how do pts with aortic dissections present? |
|
Definition
| with "tearing away chest pain" between the scapulats, may report a rip/pop. pts will look physically sick, and may be hypertensive (hypo if they have lost a lot of blood). |
|
|
Term
| can cocaine use be correlated with aorti dissection? |
|
Definition
| yes, it can exacerbate HTN |
|
|
Term
| what is the correlation between marfan's syndrome and aortic dissections? |
|
Definition
| in marfan's syndrome, there is a defect in fibrillin w/medial necrosis of the aortal wall. this can predispose a pt for aortic dissection. |
|
|
Term
| what are the different aortic dissection classifications? |
|
Definition
| type A: involves the ascending aorta (may go distally and involve the entire length of the aorta) and type B: which does not involve the ascending aorta |
|
|
Term
| can aortic dissections mimic an MI? |
|
Definition
| yes, w/a sudden onset of tearing chest and back pain (though EKGs will be different, and aortic dissections will likely have an enlarged mediastinum) |
|
|
Term
| what is the most common cause of death in industrialized countries? |
|
Definition
| CAD - accounts for a large % of people presenting to the ER |
|
|
Term
| what is one of the primary problems with CAD? |
|
Definition
| atherosclerosis - which leads to a plaque, eventually causing ischemia and ultimately infarction |
|
|
Term
| can cardiac muscle grow back? |
|
Definition
| no, if the pt survives an MI, it will grow back as fibrotic tissue lacking the contractile and conductive properties of normal myocardium |
|
|
Term
| what is myocardial ischemia defined as? |
|
Definition
| an imbalance between O2 supply and demand |
|
|
Term
|
Definition
| reduced nutrient substrates, inadequate removal of metabolites - though the *most common cause is reduction of coronary blood flow from atherosclerotic CAD* |
|
|
Term
| what is the tipping point where a pt w/CAD atherosclerosis becomes immediately at risk for an ischemic heart disease? |
|
Definition
| initially there are changes in the endothelium and intima leading to occlusion in the lumen and formation of thrombi - *but when there is change in thrombus formation, that is when the pt is acutely at risk |
|
|
Term
| what are the four types of ischemic heart disease? which is the most important? |
|
Definition
| MI (*most important form of IHD - duration and severity of ischemia is sufficient to cause death of heart muscle), angina pectoris (less severe, does not cause infarction: stable angina, prinzmental angina and unstable angina), chronic IHD w/heart failure, and sudden cardiac death |
|
|
Term
| why is an MI the most important cause of IHD? |
|
Definition
| it involves irreversible damage depending on the duration and severity |
|
|
Term
|
Definition
| a less severe form of IHD, does not cause irreversible damage to the myocardium and *it can often be relieved by rest or NO* (differentiating factor) |
|
|
Term
| what is chronic IHD w/heart failure? |
|
Definition
| a severe ischemic episode that changes the myocardium, causing it to lose some of the contractile features. it can have some CHF/pulmonary edema/pretibial edema associated with it |
|
|
Term
| is sudden cardiac death considered a form of IHD? |
|
Definition
| yes (definitions of time frame vary) |
|
|
Term
| what are the 2 ends of the clinical presentation spectrum for IHD? |
|
Definition
| young people w/minimal CAD presenting with AMI or sudden death to elderly people asymptomatic w/severe atherosclerosis |
|
|
Term
| what does the presentation of IHD depend on? |
|
Definition
| plaque morphology and its changes; erosion, ulceration, fissuring, rupture, hemorrhage, and superimposed thrombus. collateral circulation may develop due to angiogenic stimulation of blood vessels due to decreased blood flow. |
|
|
Term
| how does hemorrage w/IHD present? |
|
Definition
| hemorrage can occur right under the plaque and results in ballooning, encroaching into the lumen |
|
|
Term
| how does a superimposed thrombus present in IHD? |
|
Definition
| injured endothelium's state can change from anticoagulant to procoagulant |
|
|
Term
| is it common for pts with CAD to have multiple vessels affected? |
|
Definition
| yes, more than 90% of people with CAD will have changes in more than one vessel |
|
|
Term
| what is the "widow maker"? |
|
Definition
| the proximal left anterior descending coronary artery being occluded, while the rest of the coronary arteries are clear |
|
|
Term
| what are the most commonly affected coronary arteries? |
|
Definition
| LAD (left anterior descending), LCX (left circumflex), and the RCA (right coronary artery) |
|
|
Term
| what can slowly developing atherosclerotic lesions in the coronary vessels develop? |
|
Definition
|
|
Term
| the more proximal (to their origin) the atherosclerotic plaque/lesion is, ___________ |
|
Definition
| the more damage to the myocardium |
|
|
Term
| what is the progression of changes leading to CAD? |
|
Definition
| development of atherosclerosis (lipid deposition, macrophage engulfed oxidized LDLs, cholesterol/cholesterol esters form atheroma), vessel encroachment/occulusion, decreased cross sectional area/blood flow (at this point, pts likely have stable angina w/exercise), as the lumen occludes, pain will start to occur at rest. ischemia and infarctions become likely at this point, though the pt is relatively safe until 75% of the lumen is compromised. the atheroma may then progress to a plaque, which can disrupt/aggregate platelets forming thrombi - which further occlude the lumen, sometimes to 100%. |
|
|
Term
|
Definition
| angina with little to no activity |
|
|
Term
| why would you most likely see changes to the endocardium first in situations of ischemia? |
|
Definition
| it is the farthest away from the blood supply, so pathology may be limited to just a subendothelial infarct |
|
|
Term
| what is a transmural infarct? |
|
Definition
| when the entire transverse wall of the vessel is affected = sudden death |
|
|
Term
| what are intrinsic influences on changes in plaque morphology? |
|
Definition
| the plaque structure itself may become compromised; fibro-fatty cap may be disrupted or hemorrhages in the plaque may enlarge and push into the lumen of the vessel |
|
|
Term
| what are extrinsic influences on changes in plaque morphology? |
|
Definition
| a high BP can produce stress and shearing forces, and the platelets may begin to accumulate on the plaque |
|
|
Term
| can plaques withstand mechanical stress such as exercise? |
|
Definition
| not well, this increases O2 demand as well as increased BP |
|
|
Term
| what are examples of vulnerable plaques? |
|
Definition
| plaques w/large areas of foam cells and extracellular lipid, those that have thin/fragile fibrous caps (fissures often occur at the junction of the cap and the rest of the plaque), and those which contain few smooth muscle cells or clusters of inflammatory cells |
|
|
Term
| where do fissures often occur in CAD? |
|
Definition
| at the junction between the fibrous cap and the rest of the plaque, this is the area most prone to shearing forces |
|
|
Term
| what accounts for fibrous cap stability and good prognosis? |
|
Definition
| synthetic and degradation activity of the collagen |
|
|
Term
| what is collagen in atherosclerosis produced by? what degrades it? |
|
Definition
| collagen is made by the smooth muscle cells and degraded by metalloproteinases made by macrophages |
|
|
Term
| what effect can enzymatic (metalloproteinase) activity have on atherosclerotic plaque stability? |
|
Definition
| if the collagen is being broken down, this can lead to hemorrage and/or loosening of the plaque and subsequent problems |
|
|
Term
| how does inflammation affect plaques? |
|
Definition
| inflammation destabilizes plaques |
|
|
Term
| how does adrenergic stimulation affect plaques? |
|
Definition
| adrenergic stimulation can stress plaque by HTN and vasospasm (coronary artety going into spasm, can be caused by cocaine) |
|
|
Term
| how can a change in plaque affect a minimally occluded artery? |
|
Definition
| even minimally occluded arteries can be completely occluded by changes in plaque |
|
|
Term
| how does collagen affect thrombi formation? |
|
Definition
|
|
Term
| how does inflammation in CAD proceed? |
|
Definition
| the initial lesion needs some interaction between endothelial cells and leukocytes, which can be initiated by endothelial cell release of chemokine and expression of adhesion proteins: ICAM and VCAM - which cause the leukocytes to adhere to the endothelium |
|
|
Term
| how do T cells kick off the formation of foam cells? |
|
Definition
| T cells produce cytokines that activate macrophages, signalling the macrophages to engulf oxidized LDLs |
|
|
Term
| what can C-reactive protein serve as a marker for? |
|
Definition
| C-reactive protein can serve as a potential marker of atherosclerosis |
|
|
Term
| what is one of the most common things that will result in a quick reduction in the lumen? |
|
Definition
| a coronary thrombus (a clot the size of a pencil tip can kill you) and they can also embolize to even more distal sites and occlude them |
|
|
Term
| can thrombi promote growth of new atheromas? |
|
Definition
|
|
Term
|
Definition
| yes, with thrombolytic therapy coronary artery flow can be re-established |
|
|
Term
| what is the role of vasoconstriction in CAD? |
|
Definition
| vasoconstriction can compress the lumen, increasing the mechanical structures which can upset a plaque or result in ischemia. vasospams can also be kicked of by vasoconstriction = ischemia |
|
|
Term
| what can vasoconstriction be stimulated by? |
|
Definition
| adrenegic agents, released platelet conents, impaired secretion of endothelial cell relaxing factors, mediators released from perivascular inflammatory cells, and cocaine |
|
|
