Flashcards in Cardiovascular Deck (38):
Where do the following heart structures come from?
1. Ascending aorta and pulmonary trunk
2. smooth parts of left and right ventricles
3. trabeculated left and right ventricles
4. trabeculated left and right atria
5. coronary sinus
6. smooth part of right atrium
1. Truncus arteriosus --> ascending aorta and pulmonary trunk
2. Bulbus cordis --> smooth part of left and right ventricles
3. Primitive ventricle --> trabeculated L and R ventricle
4. Primitive atria --> trabeculated L and R atria
5. Left horn of sinus venosus --> coronary sinus
6. Right horn of sinus venosus --> smooth parts of right atrium
7. Right common cardinal vein and right anterior cardinal vein --> SVC
How does the ascending aorta and pulmonary trunk form?
Neural crest migrates to form the truncal and bulbar ridges that spiral and fuse to form the aorticopulmonary septum
What forms due to failure of the AP septum to spiral?
Transposition of great vessels
What happens when you have a skewed AP septum?
tetraology of Fallot
What happens when you have a partial AP septum development?
persistent Truncus arteriosus
What are the steps for IV septum development of the heart?
1. muscular ventricular septum forms. opening is called the interventricular foramen
2. AP septum rotates and fuses w/ muscular ventricular septum to form membranous interventricular septum closing the foramen
3. Growth of endocardial cushions separates atria from ventricles and contributes to both atrial separation and membranous portion of the IV septum
What are the steps for interatrial septum development?
1. foramen primum narrows as septum primum grows toward endocardial cushion
2. Perforations in septum primum form foramen secundum (foramen primum disappears)
3. Foramen secundum maintains R to L shunt as septum secundum begins to grow
4. Septum secundum contains a permanent opening (foramen ovale)
5. Foramen secundum enlarges and upper part of septum primum degenerates
6. Remaining portions of septum primum forms valve of foramen ovale
7. Septum secundum and septum primum fuse to form the atrial septum
8. Foramen ovale usually closes soon after birth b/c of increased LA pressure
Where does fetal erythropoiesis occur?
Yolk sac - 3- 10 wks
Liver - 6 wk to birth
Spleen - 15 to 30 wks
Bone marrow - 22 wk to adult
* Young liver synthesis blood
What fetal vessels have more oxygentaed blood?
- umbilical vein is 80% saturated w/ O2 and a PO2 of 30 mmHg
What is the flow of blood in a fetus?
1. umbilical vein from placenta carries oxygenated blood to Ductus Venosus into the IVC to bypass the hepatic circulation
2. Most oxygenated blood reaching the heart via the IVC is diverted thru the foramen ovale and pumped out the aorta to the head and body
3. Deoxygenated blood entering the RA from the SVC enters the RV, is expelled into the pulmonary arteries and then passes thru the ductus arteriosus into the descending aorta.
What happens when an infant takes its first breath?
- decreased resistance in pulmonary vasculature b/c of decreased intrathoracic pressure = increased left atrial pressure vs right atria pressure
- foramen ovale closes
- increase in O2 leads to decreased in PGs causing closure of ductus arteriosus
What can help close the Patent ductus arteriosus?
Indomethacin - blocks PGs
What helps keep PDA open?
PG E1 and E2
What are the remnants of the following fetal-postnatal derivatives?
1. umbilical vein
2. umbilical arteries
3. ductus arteriosus
4. ductus venosus
5. foramen ovale
1. umbilical vein --> ligamentum teres hepatis (contained in falciform ligament)
2. umbilical artery --> medial umbilical ligament
3. ductus arteriosus --> ligamentum arteriosum
4. ducuts venosus --> ligamentum venosum
5. foramen ovale --> fossa ovalis
6. allantois --> urachus-medial umbilical ligament
7. notochord --> nucleus pulposus of IV disc
What artery supplies the SA and AV nodes?
What are the branches of the RCA in the heart?
1. acute marginal artery supplies RV
2. posterior descending/IV artery - supplies posterior 1/3 of IV septum and posterior walls of ventricles. Most people get PD from RCA
What happens w/ left dominant circulation of codominant circulation of the heart?
1. left - PD arises from LCV
2. mixed - PD arises from both LCX and RCA
What is the MC site of occulsion in the coronary artery?
When are coronary arteries supplied and filled w/ oxygenated blood?
What is the most posterior part of the heart?
left atrium -- enlargement can cause dysphagia (due to compression of esophagus) or hoarseness (due to compression of left recurrent laryngeal nerve)
Why is transesophageal echo useful?
can dx left atrial enlargement, aortic dissection, and thoracic aortic aneurysm
What are the branches of the LCA?
1. left circumflex artery - supplies lateral and posterior walls of LV
2. LAD - supplies anterior 2/3 of IV septum, anterior papillary muscle, and anterior surface of LV
3. Left marginal artery
What is CO?
CO = SV * HR
What is Fick's principle?
CO = rate of O2 consumption/(arterial O2 content - venous O2 content)
What is the equation for Mean Arterial pressure?
MAP = CO * TPR
MAP = 2/3 diastolic pressure + 1/3 systolic pressure
What is pulse pressure?
systolic pressure - diastolic pressure
estimates to SV
What is an equation of SV?
SV = CO/HR
SV = EDV - ESV
What happens to CO during exercise?
1. during early stages = CO maintained by increased HR and SV
2. during late stages = CO maintained by increased in HR
What happens if HR gets too high?
diastolic filling is incomplete and CO decreases
What are the variables that affect CO?
SV - which is affected by contractility, afterload, and preload
How does SV change?
1. increased w/ increase contractility and preload and decreased afterload
- increase in anxiety, exercise, and pregnancy
- decrease in failing heart
How does contractility increase?
1. catecholamines (increased activity of Ca pump in SR)
2. increased intracellular Ca
3. decreased extracellular Na = decreases activity of Na/Ca exchanger = increases IC Ca
4. Digitalis - blocks NaKATPase = decreases Na/Ca exchanger activity = increased IC Ca
How does contractility decrease?
1. Beta blockers - decrease cAMP
2. heart failure - systolic dysfunction
5. non-dihydropyridine CCB
What increases myocardial O2 demand?
1. increased afterload = arterial pressure
2. increased contractility = increased muscle work
3. increased HR
4. increased heart size (increases wall tension)
What is the bottom goal in treatment for a heart attack?
- decrease afterload and contractility to decrease myocardial O2 demand
What is preload and afterload?
1. preload = EDV
2. afterload = mean arterial pressure
What increased preload?
exercise, increased blood volume, excitement, pregnancy due to increased BV