Path Cardio Outline - TMedWeb

Path Cardio OutlineISCHEMIC HEART DISEASEIschemia is defined as a mismatch between myocardial oxygen supply and demand. Whether ithappens over years or happens right now, if there is not enough supply, the myocardium will suffer.Types of IschemiaLumenConcentric Plaque‐ Chronico Caused by atherosclerosis, with the formation of plaques and a concentric stenosis ofthe coronary vessels leading to decreased blood flow. May be associated withvasospasm, thrombosis, or embolus.• At 75% occlusion, 25% flow, patients will experience exercise induced ischemia• At 90% occlusion, 10% flow, patients will experience ischemia at rest.o This represents the little old lady with years of smoking and fried chicken, with sufficientstenosing of her vessels• Multiple angina events will indicate ischemic disease, and can be managed‐ Acuteo Caused by vasospasm, embolus, or thrombosis without previous indication of ischemicdisease. The first event is the Myocardial Infarction that kills them.• There is no significant stenosis, there is no induced angina/ischemia• May be histological indications, eccentric non stenosing plaques.o This is the 16 year old kid who does cocaine, suffering from an increased heart rate(increase myocardial demand) with vasospasm, reporting the ER with chest painCauses of Ischemia‐ Acute Plaque Changeo Changes in the condition of a stable plaque (either concentric/nonconcentric) lead tothrombosis and complete occlusion of a vessel• Rupture/Fissure = exposes highly thrombogenic plaque interna• Ulceration/Erosion = exposes highly thrombogenic basement membrane• Fragmentation/Embolus = plaque breaks off and occludes smaller vessel (rare)o Intrinsic plaque Influences• Increase in Foam Cells, Lipids, thin fibrous cap, Increase Inflammatory cells allincrease the risk of plaque changeo Extrinsic Plaque Influences• An increase in mechanical stress on a weak fibrous cap leads to damage• Adrenergic Stimulation, Emotional Stress, even the awakening from sleep allincrease cardiac output and predispose for increased mechanical stress11 | O wl Club Review Sheets