Term
| THe third sinus of valsalva is also called the _________. |
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Definition
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Term
| What are the two large subdivisions of the LCA and what do they supply? |
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Definition
| the left anterior descending (antero-apical portion) and the left circumflex (postero-lateral portion) |
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Term
| Describe the branches of the LAD. |
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Definition
| has penetrating branches into the septum which perfuse its anterior two thirds and also has 1-3 diagonal branches which course leftward over the anterior surface and supply a portion of the LV anterior wall |
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Term
| What artery is the blood supply of the apex? |
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Definition
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Term
| Where can you find the LCF (left circumflex)? |
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Definition
| runs laterally in the AV groove which marks the separation bewtween LV and LA |
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Term
| Describe the branches of the LCF. |
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Definition
| gives off several "marginal" branches as it turns posteriorly in the AV groove. These marginal vessels course towards the apex and are an important source of blood supply for the lateral portion of the LV |
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Term
| In 10% of hearts, the LCF continues in the AV groove to the crux where it gives off the... |
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Definition
| posterior descending branches in the posterior IV groove |
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Term
| The posterior descending branches supply... |
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Definition
| the posterior one third of the interventricular septum and the AV node (if the posterior descending came off of the LCF) |
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Term
| What is a left dominant circulation of the heart? |
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Definition
| when the entire LV and septum are supplied by the left coronary system. |
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Term
| In 45% of left dominant circulation, the proximal LCF supplies the... |
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Definition
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Term
| Where do you find the right coronary artery? |
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Definition
| in the right AV groove and reaches the crux in 90% of hearts, thereby supplying the inferior wall |
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Term
| As the RCA is supplying the inferior wall, it gives off which branches? |
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Definition
| AV nodal artery, several posterior descending branches, and a branch which continues across the crux in the posterior left AV groove |
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Term
| In what percent of patients does the SA nodal artery arise from the proximal RCA? |
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Definition
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Term
| When you can't establish whether a heart is left dominant or right dominant it is called ______. |
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Definition
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Term
| What is the conus artery? |
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Definition
| an artery in 50% of people that arises from the right coronary sinus and serves as an important potential source of collateral blood supply to the left system |
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Term
| List some rare atomic variations on the origin of the coronary arteries. |
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Definition
| origin of both arteries from the right or left sinus of valsalva, origin of one coronary artery from the pulmonary artery and coronary artery-venous fistula |
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Term
| What are thebesian veins? |
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Definition
| small veins carrying little blood, primarily from the right heart and emptying directly into the RV |
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Term
| What are the anterior cardiac veins? |
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Definition
| intermediate veins draining most of the RV and emptying directly in the the RA |
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Term
| What is the major venous drainage system of the heart? |
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Definition
| coronary sinus and its tributaries which carry 85-90% of the LV venous effluent |
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Term
| Where is the coronary sinus found and what supplies it? |
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Definition
in the posterior AV groove
recieves tributaries from the LV areas successively supplied by the ALD, LCF, and RCA until finally emptying into the RA |
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Term
| What supplies the interventricular septum? |
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Definition
septal branches of the LAD for the ant 2/3 of the septum
posterior descending branches for the post 1/3 of septum from RCA (90%) or LCF (10%) |
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Term
| Describe the blood supply of the left anterior papillary muscle. |
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Definition
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Term
| Describe the blood supply of the left posterior papillary muscle. |
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Definition
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Term
| T/F Papillary muscle dysfunction is often the result of a single vessel occlusion. |
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Definition
| FALSE! b/c papillary muscles have dual blood supply. However they are susceptible to vascular insufficiency nontheless |
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Term
| Which part of the papillary muscle is difficult to perfuse? |
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Definition
| the apices (artery must go thru ventricular wall then turn upwards and go 2x the thickness of LV wall to get to apex) subjects vessels to intramural wall tension |
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Term
| Which papillary muscle has a poorer blood supply? |
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Definition
| posterior papillary muscle |
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Term
| What arteries supply the SA node? |
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Definition
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Term
| Which arteries supply the AV node? |
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Definition
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Term
| T/F unlike skeletal muscle, myocardium has little capacity for anaerobic glycolysis. |
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Definition
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Term
| T/F Myocardium stores large amounts of oxygen. |
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Definition
| false! instead, oxygen extraction is normally near-maximal |
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Term
| In the normal heart, coronary blood flow is directly proportional to _________ consumption. |
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Definition
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Term
| What percent of myocardial energy consumption is used to generate contraction? |
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Definition
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Term
| What are the three principle determinants for increasing myocardial energy consumption. |
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Definition
| heart rate, wall tension (preload and afterload), contractility (inotropic state) |
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Term
| Exercise increases myocardial oxygen consumption by increasing... |
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Definition
| heart rate, afterload (elevation of systolic blood pressure), and contractility (by catecholamine stimulation) |
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Term
| What are the determinants of myocardial oxygen supply? |
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Definition
major: coronary perfusion pressure and coronary vascular resistance
minor: Hgb content of blood, oxygen hemoglobin dissociation curve, blood viscosity |
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Term
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Definition
| (pressure gradient)/(resistance [coronary]) |
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Term
| What are the four major factors that affect coronary blood flow: |
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Definition
| 1) anatomic 2) hydraulic 3) metabolic and 4) neuro-humoral factors |
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Term
| Why is there a large pressure drop that occurs in intramural vessels and in the arterioles to the heart? |
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Definition
| because they come off at right angles from th epicardial arteries |
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Term
| What are coronary collaterals? |
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Definition
| Anastomotic connections (without intervening capillaries) that exist between segments of the same vessel or between different vessels.Considerable varation between individuals. Less than 40 um in diameter usually unless slow plaque buildup |
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Term
| The bulk of blood flow to teh left ventricule myocardium occurse during _____. |
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Definition
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Term
| T/F Blood flow to the right ventricle is little affected by systole. |
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Definition
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Term
| The compressive effects of systole can account for _____% of total coronary vascular resistance. |
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Definition
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Term
| Where is the compressive force of systole on myocardial blood flow especially pronounced? |
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Definition
| in the subendocardial layers where wall tension is highest |
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Term
| Is vascular tone in the subendocardium higher or lower than in the subepicardium? |
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Definition
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Term
| Why is the subendocardium more prone to ischemia? |
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Definition
| diminished vasodilatory reserve |
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Term
| What does it mean to say that coronary vascular beds normally exhibit autoregulation? |
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Definition
| blood flow is relatively constant over a wide range (60-120 mmHg) of perfusion pressures. |
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Term
| Is autoregulation more prominent in subepicardium or subendocardium? |
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Definition
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Term
| In what clinical scenario would a coronary perfusion depend solely on perfusion pressure? |
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Definition
| if there is a fixed coronary obstruction and the bed is already maximally vasodilated |
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Term
| Why is hypotension and artherosclerotic coronary artery disease a bad combination? |
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Definition
| because artherosclerotic coronary arteries may be maximmaly dilated and depend solely on blood pressure to perfuse the heart |
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Term
| Are oxygen, K+, Ca2+, and osmolality likely or unlikely mediators of coronary tone? |
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Definition
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Term
| Are adenosine and other nucleotides, prostaglandins, CO2, and H+ likely or unlikely mediators of coronary tone? |
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Definition
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Term
| What is the most important mediator of metabolic vasodilation? |
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Definition
| adenosine, which is released when demand exceeds cells ability to resynthesize high-energy phosphate, either due to increased demand or decreased perfusion pressure and O2 supply |
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Term
| Besdies adenosine, what other metabolic factos are involved in metabolic vasodilation? |
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Definition
| H+, Co2, acetate, lactate |
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Term
| Under what perfusion pressure does metabolic vasodilation become maximal and coronary blood flow become directly dependent on perfusion pressure? |
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Definition
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Term
| What type of neural receptors do coronary vessels contain? |
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Definition
| alpha adrenergic and beta2 adrenergic receptors |
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Term
| Infusion of alpha 1 or 2 adrenergic agonists (methoxamine, clonidine) has what effect on the coronary vessels? |
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Definition
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Term
| Infusion of beta 2 agonists such as isoproterenol causes what kind of reaction in coronary vessels? |
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Definition
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Term
| In humans the net effect of sympathetic stimulation to coronary vessels is ______. |
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Definition
| vasodilation (intense metabolic vasodilation induced by beta 1 stimulation overwhelms the weaker alph mediated vasoconstriction |
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Term
| NO is synethesized and released by normal endothelial cells in response to ... |
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Definition
| a variety of hormonal and mechanical stimuli including ACh, thrombin, serotonin, and shear stress |
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Term
| How does NO cause vasodilation? |
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Definition
| activates guanylate cyclase (cGMP) in adjascent vascular smooth muscle cells to cause coronary vasodilation (in the presence of intact endothelium) |
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Term
| What does nitroglycerin do? |
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Definition
| causes coronary vasodilation by being metabolized directly in the smooth muscle cell to nitric oxide (vasodilation without intact endothelium) |
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Term
| What are the two vasoactive and platelet active products of normal endothelium? |
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Definition
| NO and prostacyclin (act to inhibit platelt adhesion and aggregation and to relax vascular smooth muscle) |
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Term
| What disease processes impair the release of NO? |
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Definition
| hypertension and atherosclerosis |
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Term
| Why is the endothelium important in regulating coronary vessel dilation? |
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Definition
| infusion of ACh in normal coronary causes endothelium to release NO which causes vasodilation. In artherosclerotic coronary artery in which endothelium is often dysfunctional or absent, acetyl choline infusion causes direct vasoconstriction of vessel smooth muscle cells. |
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Term
| What is endothelin-1? What produces it, what does it do, and what molecules stimulate its production? |
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Definition
| endothelial cells, potent vasoconstrictor that partially counteracts the actions of endothelial vasodilators, expression is stimulated by thrombin, angiotensin II, and epinephrine |
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