Cardiovascular Flashcards – First Aid for the USMLE STEP 1

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  • Truncus arteriosus gives rise to what?
    ascending aorta and pulmonary trunk
  • bulbus cordis gives rise to what?
    smooth parts (outflow tract) of left and right ventricles
  • primitive ventricle gives rise to what?
    trabeculated left and right ventricles
  • primitive atria give rise to what?
    trabeculated left and right atria
  • left horn of sinus venosus gives rise to what?
    coronary sinus
  • right horn of SV gives rise to what?
    smooth part of right atrium
  • right common cardinal vein and right anterior cardinal vein give rise to what?
    SVC
  • what happens in the normal development of the truncus arteriosus?
    neural crest migration --> truncal and bulbar ridges that spiral and fuse to form the aorticopulmonary (AP) septum--> ascending aorta and pulmonary trunk
  • what are the truncus arteriosus pathologies?
    1. TGA 2. ToF 3. TA
  • what is the defect in transposition of the great vessels?
    failure to spiral
  • what is the TA defect in tetralogy of Fallot?
    skewed AP septum development
  • what is the defect in persistent TA?
    partial AP septum development
  • 3 steps in embryologic formation of interventricular septum?
    1. muscular ventricular septum forms 2. AP septum rotates to form membranous interventricular septum 3. Endocardial cushions separates atria from ventricles and contributes to both atrial separation and membranous portion of the interventricular septum
  • improper neural crest migration into the TA can result in what?
    transposition of the great arteries or a persistent TA
  • "in interventricular septum development, membranous septal defect causes what?"
    "an initial left to right shunt, which later reverses to a right to left shunt due to onset of pulmonary hypertension (Eissenmenger's syndrome)"
  • 8 steps in interatrial septum development?
    1. Septum primum grows to endocardial cushions 2. perforations in septum primum form foramen secundum 3. Septum secundum begins to grow 4. septum secundum contains a permanent opening (foramen ovale) (refer to book for more info)
  • what happens in pathology of interatrial septal development?
    "patent foramen ovale, caused by failure of the septum primum and septum secundum to fuse after birth"
  • when is there fetal erythropoiesis in the yolk sac?
    3-10wk
  • when is there fetal erythropoiesis in the liver?
    6wk-birth
  • when is there fetal erythropoiesis in the spleen?
    15-30wk
  • when is there fetal erythropoiesis in the bone marrow?
    22wk-adult
  • mnemonic for fetal erythropoiesis?
    young liver synthesizes blood
  • structure of HbF?
    alpha2gamma2
  • structure of HbA?
    alpha2beta2
  • O2 content of fetal blood in the umbilical vein?
    PO2~30 80% saturated with O2
  • O2 sat of umbilican arteries?
    low
  • sites of 3 important shunts of fetal circulation?
    1. ductus venosus 2. foramen ovale 3. ductus arteriosus
  • action of shunt at ductus venosus in fetal circulation?
    blood entering the fetus through the umbilical vein is coducted via the ductus venosus into the IVC to bypass the hepatic circulation
  • action of the shunt at the foramen ovale in fetal circulation?
    most oxygenated blood reaching the heart via the IVC is diverted through the foramen ovale and pumped out the aorta to the head and body
  • action of the shunt at the ductus arteriosus in fetal circulation?
    "deoxygenated blood entering the RA from the SVC enters the RV, is expelled into the pulmonary artery, then passes through the ductus arteriosus into the descending aorta"
  • what happens to fetal circulation at birth when the infant takes a breath?
    "(decrease) resistance in pulmonary vasculature causes (increase) LA pressure vs RA pressure--> foramen ovale closes (now called fossa ovalis) --> (increase) in O2 leads to (decrease) in prostaglandins, causing closure of ductus arteriosus"
  • what helps close PDA?
    indomethacin
  • what keeps PDA open?
    "PGE1, PGE2"
  • post natal derivative of the umbilical vein?
    "ligamentum teres hepatis, contained in falciform ligament"
  • postnatal derivatives of umbilical arteries?
    medial umbilical ligaments
  • postnatal derivatives of ductus arteriosus?
    ligamentum arteriosum
  • postnatal derivative of ductus venosus?
    ligamentum venosum
  • postnatal derivative of foramen ovale?
    fossa ovalis
  • postnatal derivative of allantois?
    urachus-median umbilical ligament
  • what is the urachus part of?
    the allantoic duct between the bladder and the umbilicus
  • what finding is a remnant of the urachus?
    "urachal cyst, or sinus"
  • postnatal derivative of the notochord?
    nucleus pulplosus of intervertebral disc
  • LCX supplies what?
    lateral and posterior walls of left ventricle
  • LAD supplies what?
    "anterior 2/3 of interventricular septum, anterior papillary muscle, and anterior surface of left ventricle"
  • PD supplies what?
    posterior 1/3 of interventricular septum and posterior walls of ventricles
  • acute marignal artery supplies what?
    right ventricle
  • SA and AV nodes are usually supplied by what?
    RCA
  • frequency and features of right dominant coronary circulation?
    85% PD arises from RCA
  • frequency and features of left-dominant coronary circulation?
    8% PD arises from LCX
  • frequency and features of codominant circulation?
    7% PD arises from both LCX and RCA
  • coronary artery occlusion most commonly occurs where?
    in LAD
  • when do coronary arteries fill?
    during diastole
  • most posterior part of the heart is what?
    LA
  • enlargement of LA can cause what?
    dysphagia (due to compression of the esophagus) or hoarseness (due to compression of the left recurrent laryngeal nerve)
  • transesophageal echocardiography is useful for diagnosing what?
    LA enlargement aortic dissection thoracic aortic aneurysm
  • equations for cardiac output?
    CO= SV x HR Fick's: CO= (rate of O2 consumption)/((arterial O2 content) - (venous O2 content))
  • equation for MAP?
    MAP= CO x TPR MAP= 2/3 diastolic pressure + 1/3 systolic
  • pulse pressure=?
    systolic pressure - diastolic pressure
  • pulse pressure is proportional to what?
    stroke volume
  • equations for stroke volume?
    SV = CO/HR = EDV - ESV
  • during the early stages of exercise CO is maintained by what?
    (increase) HR and (increase) SV
  • "during the late stages of exercise, CO is maintained by what?"
    (increase) HR only (SV plateaus)
  • what happens during exercise if HR is too high?
    diastolic filling is incomplete and CO (decrease)
  • cardiac variables that affect stroke volume?
    "SV CAP Stroke Volume affected by Contractility, Afterload, and Preload"
  • (increase) SV when what?
    "(increase) preload, (decrease) afterload, (increase) contractility"
  • contractility (and SV) (increase) with what?
    1. catecholamines 2. (increase) intracellular Ca++ 3. (decrease) extracellular Na+ 4. Digitalis
  • how do catecholamines (increase) contractility?
    (increase) activity of Ca++ pump in sarcoplasmic reticulum
  • how does a (decrease) in extracellular Na+ (increase) contractility?
    (decrease) activity of Na+/Ca++ exchanger
  • how does digitalis (increase) contractility?
    blocks Na+/K+ pump --> (increase) intracellular Na+ -->(decrease) Na+/Ca++ exchanger activity --> (increase) intracellular Ca++
  • contractility and SV (decrease) with what?
    1. beta blockade 2. heart failure (systolic dysfunction) 3. acidosis 4. hypoxia/hypercapnia ((decrease)PO2/(increase)PCO2) 5. Non-dihydropyridine Ca++ channel blockers
  • "effect of anxiety, exercise, and pregnancy on SV?"
    (increase)
  • myocardial O2 demand is (increase) by what?
    (increase) afterload (proportional to arterial pressure) (increase) contractility (increase) heart rate (increase) heart size ((increase)wall tension)
  • preload = ?
    ventricular EDV
  • afterload=?
    MAP (proportional to peripheral resistance)
  • agents that (decrease) preload?
    vEnodilators (nitroglycerin)
  • agents that (decrease) afterload?
    vAsodilators (hydrAlazine)
  • preload (increase) with what?
    1. exercise (slightly) 2. (increase) blood volume (overtransfusion) 3. excitement ((increase) sympathetic activity)
  • "on Starling curve, force of contraction is proportional to what?"
    end-diastolic length of cardiac muscle fiber (preload)
  • "on Starling curve, what are the factors that increase contractility?"
    sympathetic stimulation catecholamines digoxin
  • "on starling curve, which factors (decrease) contractility?"
    loss of myocardium (MI) beta blockers Ca++ channel blockers
  • equation for EF?
    EF= SV/EDV = (EDV-ESV)/EDV
  • EF is an index of what?
    ventricular contractility
  • normal EF?
    >=55%
  • EF (decrease) in what?
    systolic heart failure
  • deltaP =?
    Q x R
  • equation for resistance?
    resistance = (driving pressure deltaP)/(Flow Q)= (8nl)/#r^4
  • equation for total resistance of vessels in series?
    = R1 + R2 + R3
  • 1/Toral Resistance of vessels in parallel?
    = 1/R1 + 1/R2 + 1/R3...
  • viscosity (increase) in what?
    1. polycythemia 2. hyperproteinemic states (multiple myeloma) 3. hereditary spherocytosis
  • viscosity (decrease) in what?
    anemia
  • pressure gradient drives blood flow where?
    from high pressure to low pressure
  • resistance is proportional to what?
    viscosity and vessel length
  • viscosity is inversely proportional to what?
    the radius to the 4th power
  • what accounts for most of total peripheral resistance?
    arterioles
  • what vessels regulate capillary flow?
    arterioles
  • where is the operating point of the heart on the cardiac and vascular function curve?
    intersection where cardiac output and venous return are equal
  • what causes the operating point of the heart on the cardiac and vascular function curve to shift straight down?
    "(increase) TPR, hemorrhage before compensation can occur"
  • what causes the operating point of the heart on the cardiac an vascular function curve to shift straight up?
    "(decrease) TPR, exercise, AV shunt"
  • what causes the operating point of the heart to shift downward and rightward along the venous return curve on the cardiac and vascular function curve?
    heart failure narcotic overdose
  • what causes an upward shift in the CO curve?
    + inotropy
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