Cardiovascular Disease Flashcards
Truncus arteriosus
Embryonic structure that gives rise to ascending aorta and pulmonary trunk
Bulbus cordis
Embryonic structure that gives rise to outflow tract of R and L ventricles
Primitive atrium and primitive ventricle
Give rise to trabeculated portions of atria and ventricles
Primitive pulmonary vein
Gives rise to smooth part of left atrium
Left and right horns of sinus venosus
Left gives rise to coronary sinus
Right gives rise to smooth part of right atrium
Embryonic structures that give rise to SVC
Right common cardinal vein and right anterior cardinal vein
Cardiac looping
Starts at week 4 and establishes the right-left polarity.
Dextrocardia
Seen in Kartagener as left-right dynein is required for proper cardiac looping
Atrial septation
- Septum primum grows
- Foramen secundum forms in septum primum
- Septum secundum forms; foramen secundum maintains R to L shunt
- Septum secundum expands leaving just small opening, the foramen ovale
- Septum primum and secundum fuse to form atrial septum
- Increased LA pressure closes foramen ovale after birth
Ventricular septation
- Muscular ventricular septum forms with interventricular foramen as an opening
- Formation of membranous interventricular septum
- Endocardial cushions grow to separate atria from ventricles. Contribute to atrial septation as well as the membranous portion of the interventricular septum
Fetal erythropoiesis
Yolk sac from week 3-8
Liver from 6 weeks to birth
Spleen from 10-28 weeks
Bone marrow from 18 weeks to adult
Fetal hemoglobin
Higher O2 affinity due to less 2,3 BPG binding
Fetal circulation: umbilical vein and artery
Umbilical vein brings blood from placenta to fetus. High O2 saturation
Umbilical arteries bring blood from fetus back to placenta. Low O2 saturation
Ductus venosus
Shunts blood entering the fetus through the umbilical vein to the IVC to bypass hepatic circulation
Foramen ovale
Shunts oxygenated blood entering the RA from the IVC to LA to bypass the pulmonary circulation
Ductus arteriosus
Shunts deoxygenated blood entering the RA and then RV from the SVC from the pulmonary artery to the descending aorta. Occurs due to high fetal pumonary artery resistance which is due to the low O2 tension.
Changes in circulation at birth
Infant takes a breath which causes decreased resistance in the pulmonary vasculature, allowing blood to flow through and increasing LA pressure relative to RA pressure. This causes foramen ovale to close.
Increase in O2 and decrease in PG related to placental separation results in closure of the ductus arteriosus
Adult derivative of allantois/urachus
median umbilical ligament
Adult derivative of ductus arteriosus
ligamentum arteriosum
Adult derivative of ductus venosus
Ligamentum venosum
Adult derivative of foramen ovale
Fossa ovalis
Adult derivative of notochord
Nucleus pulposus
Adult derivative of umbilical arteries
medial umbilical ligaments
adult derivative of umbilical vein
ligamentum teres which is within the falciform ligament
Blood supply to SA and AV nodes
Right coronary artery. Block can cause bradycardia or heart block
Right vs left dominant circulation
Right dominant seen in 85%. PDA arises from the RCA.
Left dominant seen in 8%. PDA arises from LCX
Codominant circulation in 7%. PDA arises from both RCA and LCX
Left atrium anatomy
Most posterior portion of the heart. Enlargement can cause dysphagia or hoarseness
Mean arterial pressure ormula
MAP=CO x TPR
MAP=2/3 diastolic pressure + 1/3 systolic pressure
Stroke volume formula
SV = EDV - ESV
Cardiac output during exercise
During early stages, CO maintained by increased HR and increased SV. During late stages, maintained by increased HR only as SV plateaus, Diastole preferentially shortened when HR increases resulting in decreased filling time and decreased CO
Causes of increased and decreased pulse pressure
Increased: hyperthyroidism, aortic regurg, aortic stiffening, OSA, exercise
Decreased: aortic stenosis, cardiogenic shock, cardiac tamponade, advanced HF
Effect of decreased sodium on heart
Decreased extracellular sodium results in decreased activity of the Na+/Ca++ exchanger, decreasing contractility
Effect of digitalis on heart
Blocks Na+/K+ pump, increasing intracellular Na+ and increasing intracellular Ca++ via decreased Na+/Ca++ exchanger activity
Formula for wall tension
Wall tension = (pressure x radium) / (2 x wall thickness)
Preload and afterload
Preload approximated by EDV. Depends on venous tone and circulating blood volume. Decreased by venodilators like nitroglycerin
Afterload approximated by MAP. Hypertrophies to compensate for increased afterolad. Decreased with vasodilators like hydralazine.
ACEs and ARBs decrease both preload and afterload
Ejection fraction
EF = SV/EDV
Decreased in systolic HF; normal in diastolic HF
Starling curve
Shows that stroke volume increases with ventricular EDV. Corresponds with the optimal sarcomere length that can generate tension.
Changes in exercise
Increase in inotropy and decreased TPR to maximize CO.
Heart sounds
S1: Mitral and tricuspid valve closure
S2: Aortic and pulmonary valve closure
S3: Heard in early diastole during rapid filling phase. Heard when there are increased filling pressures of dilated ventricles
S4: Heard in late diastole. Heard when there is high atrial pressure such as in ventricular hypertrophy due to LA pushing against a stiff LV wall
Jugular venous pulse (JVP)
a wave: atrical contraction c wave: RV contraction x descent: atrial relaxation v wave: increased RA pressure due to filling y descent: RA emptying into RV
Physiologic splitting
Inspiration causes decreased intrathoracic pressure, increasing venous return and increasing RV ejection time and delaying closure of pulmonic valve.
Wide splitting
Seen in conditions that delay RV emptying (pulmonic stenosis, right bundle branch block)
Fixed splitting
Seen in ASD due to left to right shunt that increases RA and RV volumes, increasing flow through pulmonic valve so that pulmonic closure is always delayed.
Paradoxical splitting
Seen when aortic valve closure delayed. A2 is delayed and heard after P2. During inspiration, P2 delayed, moves closer to A2, eliminating the split
Effect of inspiration on heart sounds
Increases venous return to RA increasing intensity of right heart sounds
Effect of hand gripping on heart sounds
Increases afterload, increasing intensity of MR, AR, and VSD murumurs but decreasing hypertrophic cardiomyopathy murmurs. Delays click of MVP.
Valsalva maneuvers
Decreases preload by increasing intrathoracic pressure. Decreases intensity of most murmurs, but increases intensity of hypertrophic cardiomyopathy murmur and causes earlier click of MVP.
Rapid squatting: effect on heart sounds
Increases venous return causing increased intensity of AS murmur, decreased intensity of hypertrophic cardiomyopathy murmur
Mitral valve prolapse murmur
Late systolic crescendo murmur with midsystolic click. Valsalva maneuver or standing decreases LV volume allowing prolapse to occur sooner and more severely
Myocardial action potential
Phase 0: Rapid upstroke and depolarization, VG Na+ channels open
Phase 1: Initial repolariztion due to inactivation of VG Na+ channels and opening of VG K+ channels
Phase 2: Plateau due to VG Ca++ influx balancing K+ efflux. Ca++ influx triggers Ca++ release from SR and myocyte contraction
Phase 3: Rapid replarization due to opening of VG slow K+ channels and closure of VG Ca++ channels
Phase 4: Resting potential with high K+ permeability
SERCA2
Pumps calcium back into the sarcoplasmic retirculum after cardiac contraction.
Pacemaker action potential
Phase 0: Upstroke due to opening of VG Ca++ channels. VG Na++ channels permanently inactivated because resting voltage less negative
Phase 3: Inactivation of VG Ca++ channels; opening of K+ channels and K+ efflux
Phase 4: Slow spontaneous depolarization due to funny current: both Na+ and K+ transduction. Slope determines HR
ECG: P wave, QRS, T wave, and U wave
P wave: atrial depolarization
QRS: ventricular depolarization (less than 120 ms)
T wave: ventricular repolarization
U wave: seen in hypokalemia and bradycardia