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27 Cards in this Set
- Front
- Back
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Coronary flow is largely dependent on what 3 major influences?
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1. metabolic demand
2. pressures generated by the musculature during the cardiac cycle 3. aortic hydrostatic BP |
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Avg pressures in large arteries, arterioles, capillaries, vena cava, pulmonary arteries, capillaries, and veins
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systemic...
large arteries: 120/80 arterioles: 66/60 capillaries: 18 vena cava: 0-4 pulmonary.... arteries: 24/16 capillaries: 8 veins: 6 |
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What does the umbilical vein connect to?
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fetal inferior vena cava in the liver
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In the fetus, is pressure greater in the R or L atrium?
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right atrium (R-> L shunt)
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What maintains an open ductus arteriosis?
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prostoglandins and low PO2
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What fetal structure shunts oxygenated blood away from the liver?
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ductus venosus (adult structure: ligamentum venosum)
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What happens when the umbilical arteries and veins are clamped (after birth)?
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dramatic increase in TPR (systemic)... ductus venosus closes... and closes the foramen ovale (pressure gradient switches to L --> R)
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In a normal neonate, what causes the ductus arteriosis to close?
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w/in few days after birth, hormone changes and inc. arterial 02 sat causes it to close
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What 2 major factors cause a change in BF pattern following birth?
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Inc. in systemic resistance (removal of placental circ.)
Dec. in pulmonary resistance |
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6 examples of acyanotic congenital cardiovascular defects?
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ASD, VSD, PDA, AS, post-ductal coarctation, PS
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Common compensatory change in ASD?
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dilation of right atrium and ventricle
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What are common compensatory changes in VSD?
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all chambers may dilate
LV dilation can lead to HF prolonged shunt may lead to inc. pulm. reistance and reversal shunt (eisenmengers) |
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What is a common compensatory change in PDA?
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LV dilation (inc. return), may lead to HF
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What is a common compensatory change in AS?
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LV hypertrophy (high LV systolic pressures)
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What often happens in preductal coarctation?
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ductus may remain open, if bad enough can cause R to L shunt
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What is a common compensatory change in PS? What gradient is considered mild?
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RV hypertrophy
50 mmHg gradient considered mild |
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What are 4 cyanotic congenital cardiovascular defects?
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tetralogy of fallot
ASD... w/ R -->L preductus coarctation of the aorta transposition of great vessels |
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What are intracellular changes in ischemia? extracellular?
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inc. Na and Ca, dec. K
extracellular- opposite |
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electrical/mechanical characteristics of ischemic tissue?
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dec. resting membrane potential (closer to threshold, more excitable)
cross-bridge interaction inhibited (dec. contractile force) Low amplitude AP (slow conduction) dec. CO, BP |
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Exercise stress test an produce a depressed (or elevated) ST segment. What happens to Ca++ conductance?
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It is increased in phase 4
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Exercise would produce ischemia most easily in which part of the myocardium?
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endocardial portion of the LV lateral wall
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How quickly can cell death occur after ischemia?
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w/in 20-30 minutes
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What must a dilated ventricle generate to develop the same chamber pressure (during systole) as a normal ventricle?
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greater wall tension is required
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What is atrial natriuretic factor?
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hormone secreted by the atrium in response to atrial stretching which causes renal Na+ and fluid EXCRETION
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What is BNP?
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natriuretic factor secreted by stretched ventricles, used as a clinical diagnostic marker of cardiac failure!
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Epicarditis and pericarditis can cause what to tissues?
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depolarization, which causes a negative reading during phase 4 (elevated ST in most leads)
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What does cocaine do to the heart?
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blocks reuptake of NE from symp. nerve endings (inc. stim. of beta-receptors (of heart) and alpha receptors:
results in inc. HR, intotropy, work, and BP (and coronary vascular smooth muscle contraction via alpha-R) |
