Cardiovascular

Question 1

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
7. SVC

Answer 1

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

Question 2

How does the ascending aorta and pulmonary trunk form?

Answer 2

Neural crest migrates to form the truncal and bulbar ridges that spiral and fuse to form the aorticopulmonary septum

Question 3

What forms due to failure of the AP septum to spiral?

Answer 3

Transposition of great vessels

Question 4

What happens when you have a skewed AP septum?

Answer 4

tetraology of Fallot

Question 5

What happens when you have a partial AP septum development?

Answer 5

persistent Truncus arteriosus

Question 6

What are the steps for IV septum development of the heart?

Answer 6

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

Question 7

What are the steps for interatrial septum development?

Answer 7

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

Question 8

Where does fetal erythropoiesis occur?

Answer 8

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

Question 9

What fetal vessels have more oxygentaed blood?

Answer 9

• umbilical vein is 80% saturated w/ O2 and a PO2 of 30 mmHg

Question 10

What is the flow of blood in a fetus?

Answer 10

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.

Question 11

What happens when an infant takes its first breath?

Answer 11

• 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

Question 12

What can help close the Patent ductus arteriosus?

Answer 12

Indomethacin - blocks PGs

Question 13

What helps keep PDA open?

Answer 13

PG E1 and E2

Question 14

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
6. allantois
7. notochord

Answer 14

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

Question 15

What artery supplies the SA and AV nodes?

Answer 15

RCA

Question 16

What are the branches of the RCA in the heart?

Answer 16

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

Question 17

What happens w/ left dominant circulation of codominant circulation of the heart?

Answer 17

1. left - PD arises from LCV

2. mixed - PD arises from both LCX and RCA

Question 18

What is the MC site of occulsion in the coronary artery?

Answer 18

LAD

Question 19

When are coronary arteries supplied and filled w/ oxygenated blood?

Answer 19

in diastole

Question 20

What is the most posterior part of the heart?

Answer 20

left atrium – enlargement can cause dysphagia (due to compression of esophagus) or hoarseness (due to compression of left recurrent laryngeal nerve)

Question 21

Why is transesophageal echo useful?

Answer 21

can dx left atrial enlargement, aortic dissection, and thoracic aortic aneurysm

Question 22

What are the branches of the LCA?

Answer 22

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

Question 23

What is CO?

Answer 23

CO = SV * HR

Question 24

What is Fick’s principle?

Answer 24

CO = rate of O2 consumption/(arterial O2 content - venous O2 content)

Question 25

What is the equation for Mean Arterial pressure?

Answer 25

``` MAP = CO * TPR MAP = 2/3 diastolic pressure + 1/3 systolic pressure ```

Question 26

What is pulse pressure?

Answer 26

systolic pressure - diastolic pressure | estimates to SV

Question 27

What is an equation of SV?

Answer 27

``` SV = CO/HR SV = EDV - ESV ```

Question 28

What happens to CO during exercise?

Answer 28

1. during early stages = CO maintained by increased HR and SV 2. during late stages = CO maintained by increased in HR

Question 29

What happens if HR gets too high?

Answer 29

diastolic filling is incomplete and CO decreases

Question 30

What are the variables that affect CO?

Answer 30

SV - which is affected by contractility, afterload, and preload

Question 31

How does SV change?

Answer 31

1. increased w/ increase contractility and preload and decreased afterload - increase in anxiety, exercise, and pregnancy - decrease in failing heart

Question 32

How does contractility increase?

Answer 32

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

Question 33

How does contractility decrease?

Answer 33

1. Beta blockers - decrease cAMP 2. heart failure - systolic dysfunction 3. acidosis 4. hypoxia/hypercapnea 5. non-dihydropyridine CCB

Question 34

What increases myocardial O2 demand?

Answer 34

1. increased afterload = arterial pressure 2. increased contractility = increased muscle work 3. increased HR 4. increased heart size (increases wall tension)

Question 35

What is the bottom goal in treatment for a heart attack?

Answer 35

- decrease afterload and contractility to decrease myocardial O2 demand

Question 36

What is preload and afterload?

Answer 36

1. preload = EDV | 2. afterload = mean arterial pressure

Question 37

What increased preload?

Answer 37

exercise, increased blood volume, excitement, pregnancy due to increased BV

Question 38

What effect do venodilators and vasodilators have on preload and afterload?

Answer 38

1. vEnodilators = decrease preload | 2. vAsodilators = decrease afterload