Cardiology Flashcards
Bulbus cordis gives rise to…
Smooth/outflow parts of L and R ventricles
Endocardial cushion gives rise to…
Atrial septum
Membranous interventricular septum
AV and semilunar valves
Primitive pulmonary vein gives rise to…
Smooth part of L atrium
Right horn of sinus venosus gives rise to…
Smooth part of R atrium
Right cardinal veins give rise to…
SVC
Note - Target of central line
Embryologic mechanism of dextrocardia (e.g. Kartagener syndrome).
Defect in left-right dynein involved in L/R asymmetry during cardiac looping (4 weeks).
Age at which heart beats spontaneously
4 weeks
Steps of atrial separation (4)
Septum primum (top) grows towards endocardial cushion (bottom) narrowing foramen primum
Foramen secundum forms in septum primum as it continues to close foramen primum
Septum secundum (top) grows down to cover most of foramen secundum - residual is foramen ovale
Septum primum degenerates with remainder forming valve of foramen ovale - after birth fuse to form atrial septum due to increasing LA pressure
Note - Increasing RA pressure (straining) allows R to L shunt and may lead to cryptogenic stroke
Steps of ventricular separation (3)
Muscular interventricular septum (bottom) forms with opening called interventricular foramen
Aorticopulmonary septum (truncal/bulbar ridges) rotates and grows down to fuse with muscular septum - forms membranous interventricular septum and closes interventricular foramen
Endocardial cushions grow horizontally to separate atria from ventricles - also contributes to membranous interventricular septum
Mechanism of conotruncal abnormalities…
Persistent truncus arteriosus
Transposition of great vessels
Tetralogy of fallot
Failure of neural crest cells to migrate
Fetal circulation
Oxygenated blood from umbilical vein joins IVC via ductus venosus - mostly bypasses hepatic circulation
Enters RA and goes directly to LA via foramen ovale
Deoxygenated blood from SVC goes to RA, RV, and pulmonary artery, but is shunted to descending aorta (after left subclavian) via ductus arteriosus - due to high fetal pulmonary artery resistance (low O2 tension)
Deoxygenated blood returns via umbilical arteries off of internal iliacs
Mechanism of closure of fetal circulation
Decreased resistance in pulmonary vasculature leads to increased LA pressure - foramen ovale closes
Increased O2 and decreased prostaglandins (E1/E2) from placental separation lead to closure of ductus arteriosus - closed with Indomethacin
Postnatal derivative of... Allantois/urachus Ductus venosus Ductus arteriosus Notochord Umbilical arteries Umbilical vein
Median umbilical ligament Ligamentum venosum Ligamentum arteriosum Nucleus pulposus Medial umbilical ligaments Ligamentum teres
Right acute marginal artery supplies…
Right ventricle
Posterior interventricular/Posterior descending artery (PDA) supplies…
Note - 85% have PDA come off of RCA, while minority have PDA come off of LCX
Posterior ventricular walls
Posterior 1/3 of interventricular septum
Posteromedial papillary muscles
Left circumflex artery (LCX) supplies…
Lateral and posterior walls of LV
Anterolateral papillary muscles (via obtuse/marginal)
Anterior interventricular/Left anterior descending (LAD) supplies…
Anterior surface of LV
Anterior 2/3 of interventricular septum
Anterolateral papillary muscle
Blood supply to the SA and AV nodes…
Note - infarct may cause nodal dysfunction resulting in bradycardia and heart block
RCA
Fick’s principle
CO = rate O2 consumption/(arterial O2 - venous O2)
Maintenance of CO (SV x HR) during early and late exercise
Note - SV = EDV - ESV
Early both HR and SV
Late only HR - SV plateaus
Equation for MAP (afterload)
CO x TVR
OR
(2/3)Diastolic pressure + (1/3)Systolic pressure
Mechanism for decreased CO in VT
Diastole is preferentially shortened with increasing HR, decreasing filling time
Pulse pressure in... Hyperthyroidism Aortic regurgitation Aortic stiffening (isolated systolic HTN in elderly) OSA (sympathetic tone) Exercise
Increased
Pulse pressure in... Aortic stenosis Cardiogenic shock Cardiac tamponade Advanced HF
Decreased