Test 2 - Cardiovascular Physiology

Question 1

The neonatal cardiovascular system undergoes major alterations at what point?

Answer 1

At birth.

-Congenital heart disease often accompanies other organ system malformations

Question 2

What controls the heart rate earlier in gestation than B-adrenergic control for newborns?

Answer 2

Parasympathetic control of heart rate matures earlier in gestation than B-adrenergic control

Question 3

For a newborn, vagotonic response caused by (what medication) and opioids may lead to bradycardia or asystole, This vagal reflex can be offset by (what medication)

Answer 3

Succicylcholine

Atropine

Question 4

Neonates may not respond to hypovolemia or an inadequate depth of anesthesia with what?

Answer 4

tachycardia

Question 5

For fetal circulation, what organ is the prenatal respiration? What organ is excluded from fetal circulation?

Answer 5

• The organ of prenatal respiration is the placenta

- The lungs are excluded from fetal circulation

Question 6

For fetal circulation, what are three special shunts that allow the oxygenated blood to perfuse the heart and brain?*

Answer 6

Ductus venosus
Foramen ovale
Ductus arteriosus

Question 7

What is the fetal circulation? starting from the placenta?

Answer 7

Oxygenated blood returns from the placenta via the umbilical vein > ductus venosus > inferior vena cava > RA > the saturated blood crosses the foramen ovale into the LA (cerebral circulation) > the remaining RV output crosses the ductus arteriosus (systemic flow beyond the aortic arch)

Question 8

For the fetal circulation, what % of RV output crosses the pulmonary circulation?

Answer 8

Only 10% of the RV output crosses the pulmonary circulation

Question 9

For fetal circulation, 2 umbilical arteries originate from what arteries and deliver fetal blood to the placenta?

Answer 9

Originate from the internal iliac arteries

Unoxygenated blood***

Question 10

For fetal circulation, 1 umbilical vein carries blood from the placenta to the (BLANK)

Answer 10

1 umbilical vein carries blood from the placenta to the FETUS

Oxygenated blood***

Question 11

For fetal circulation, why is the SVR low and PVR high?

Answer 11

• Low SVR secondary to the low-resistance placenta

- High PVR secondary to fluid-filled lungs and hypoxic environment

Question 12

With fetal circulation, what is the status of the pulmonary blood flow, LAP, and PAP?

Answer 12

Minimal pulmonary blood flow and low LAP

High PAP

Question 13

The most oxygenated blood from the umbilical vein perfuses the brain and heart, bypassing the liver via the (BLANK) and bypassing the RV via the (BLANK)

Answer 13

The most oxygenated blood from the umbilical vein perfuses the brain and heart, bypassing the liver via the Decutus Venosus and bypassing the RV via the Foramen Ovale

Question 14

High PVR forces most RV output across the (BLANK) into the descending aorta, allowing deoxygenated blood to return to the placenta

Answer 14

High PVR forces most RV output across the Ductus Arteriosus into the descending aorta, allowing deoxygenated blood to return to the placenta

Question 15

With oxygen delivery for the fetal circulation, what is Maternal PaO2, umbilical vein PaO2?

Answer 15

• Maternal PaO2 100 mmHg

- Umbilical vein PaO2 30-35 mmHg

Question 16

In the transitional circulation, the placental circulation is eliminated after the lungs do what?

Answer 16

The placental circulation is eliminated after the lungs expand

Question 17

In the transitional circulation, the expansion of the lungs to normal FRC results in an optimal geometric relationship of the what?

Answer 17

Expansion of the lungs to normal FRC results in an optimal geometric relationship of the pulmonary microvasculature

Question 18

In the transitional circulation, air that enters the lungs causes a marked reduction in what and increase in what?

Answer 18

Air that enters the lungs causes a marked reduction in PCO2 and increases PO2

Question 19

When does PVR decrease for a neonate?

Answer 19

PVR decreases after birth

when placental cirucaltion is eliminated after lungs expand, normal FRC returns, and air enters the lungs

Question 20

The LVED pressure increases enough to result in (BLANK) closure of the foramen ovale*

Answer 20

The LVED pressure increases enough to result in FUNCTIONAL closure of the foramen ovale

Question 21

Anatomic closure of the foramen ovale takes how long?*

Answer 21

Anatomic closure takes months to occurs*****

Question 22

Foramen ovale remains open in what % of adults?

Answer 22

25-30% of adults

Question 23

When is the Ductus arteriosus functionally closed?**

Answer 23

It is functionally closed in 98% of full term infants by day 4 of life***

Question 24

When is the Ductus arteriosus anatomic close?*

Answer 24

Anatomic closure occurs 2-3 weeks after birth**

Question 25

What triggers the ductus venosus closure?

Answer 25

With ligation of the umbilical vein, portal pressure falls, triggering closure

Question 26

How long does it take for the closure of the ductus venosus?**

Answer 26

This process requires more than 1-2 weeks****

Question 27

At birth what are the characteristics of the RV and the LV?

Answer 27

At birth, the RV and the LV are similar in size and wall thickness

Question 28

With the changeover from fetal circulation, the LV must do what two things?

Answer 28

With the changeover from fetal circulation, the LV must accommodate a greater pressure and volume workload

Question 29

With the cardiac changes at birth, the LV hypertrophies in response to what? it will become twice as heavy as the RV by what age?***

Answer 29

- The LV hypertrophies in response to the increased workload | - Becomes twice as heavy as the RV by 6 months of age

Question 30

Neonates subject to certain pathophysiologic conditions manifest severe increases in PVR, The acute load imposed on the RV may cause diastolic function and promote a what kind of shunt?

Answer 30

The acute load imposed on the RV may cause diastolic function and promote a right-to-left shunt via the foramen ovale

Question 31

With persistent fetal circulation, if PVR exceeds SVR, what kinda of shunt may develop?

Answer 31

If PVR exceeds SVR, a right-to left shunt may develop via the ductus arteriosus

Question 32

In persistent fetal circulation, life-theratening hypoxemia can occur, what may be required to sustain life?*

Answer 32

May require NO or ECMO to sustain life

Question 33

Neonatal cardiovascular system has less organized (what type of cells)?

Answer 33

The immature myocardium has less organized myocytes

Question 34

For the neonatal cardiovascular system, contractile elements constitute what % of fetal heart?

Answer 34

Contractile elements constitute 30% of the fetal heart vs 60% in the adult

Question 35

The neonatal heart relies more on (what electrolyte) influx of the sarcolemma to initiate and terminate contraction than the adult

Answer 35

The neonatal heart relies more on the CALCIUM influx of the sarcolemma to initiate and terminate contraction than the adult

Question 36

Neonates have diminished systolic and diastolic function due to the differences in what two things?

Answer 36

They have diminished systolic and diastolic function due to the differences in myocardial cell composition and calcium transport compared to adults

Question 37

In the neonatal cardiovascular system, the CO is increased due to what?

Answer 37

The CO is increased due to a high metabolic rate in the infant

Question 38

The immature neonatal heart exhibits sensitivity to pharmacologic agents that produce what two effects?

Answer 38

The immature neonatal heart exhibits sensitivity to pharmacologic agents that produce negative inotropic and chronotropic effects

Question 39

For a neonate, when does the SNS an PNS reach maturity?

Answer 39

The SNS reaches maturity by early infancy and the PNS reaches maturity within a few days of birth -Predisposes neonates to marked vagal responses

Question 40

Pulmonary vascular development is incomplete after birth, when does the pulmonary vasculature mature?

Answer 40

Pulmonary vasculature matures during the 1st few years of life

Question 41

With the pulmonary vascular development, PVR begins to decrease after birth due what two things?

Answer 41

PVR begins to decrease after birth due to lung expansion and oxygenation

Question 42

If the neonate is subject to certain pathophysiologic conditions that lead to increased PVR, what kind of shunt may develop via the ductus arteriosus? That can lead to what?***

Answer 42

If the neonate is subject to certain pathophysiologic conditions that lead to increased PVR, a R-L shunt may develop via the ductus arteriosus _*Persistent fetal circulation

Question 43

When giving anesthetics to young children you must take into account how it will affect the immature myocardium, what should you know about the inhaled anesthetics?*

Answer 43

All inhaled anesthetics are myocardial depressants

Question 44

When giving anesthetics to young children you must take into account how it will affect the immature myocardium, what should you know about midazolam?*

Answer 44

Midazolam* - Well tolerated in children with cardiac disease - Can decrease CO when combined with morphine

Question 45

When giving anesthetics to young children you must take into account how it will affect the immature myocardium, What should you know about Opioids?*

Answer 45

Opioids - Used in the field of pediatrics due to their cardiovascular stability, even at high doses - Minimal effect on HR, CO, PVR, MAP, and SVR

Question 46

When giving anesthetics to young children you must take into account how it will affect the immature myocardium, What should you know about propofol?*

Answer 46

Propofol | Can decrease BP and HR

Question 47

When giving anesthetics to young children you must take into account how it will affect the immature myocardium, What should you know about ketamine?*

Answer 47

Ketamine - Its action as a sympathomimetic preserves myocardial function - It does have depressant cardiac effects in hearts that are depleted of catecholamine's

Question 48

When giving anesthetics to young children you must take into account how it will affect the immature myocardium, What should you know about regional anesthesia?*

Answer 48

Regional anesthesia - Spinal and epidurals have minimal hemodynamic effects compared with the vasodilation in adults - Routine fluid loading is not required - Has negligible hemodynamic effects

Question 49

With congenital heart disease, 2/3 of the lesions are found in children with which genetic code?

Answer 49

2/3 of the lesions are found in children with trisomy 21

Question 50

What is shunting?**

Answer 50

Process by were venous return into one circulatory system is recirculated through the arterial outflow of the same circulatory system

Question 51

What is the pathophysiology of a "single ventricle"?

Answer 51

When there is complete mixing of pulmonary and systemic venous blood at the atrial or ventricular level.

Question 52

What is the sole source of systemic blood in a patient with a "single ventricle"?

Answer 52

During a single ventricle the PDA (patent ductus arteriosus) is the sole source of systemic blood. -Ductal dependent circulation.

Question 53

Single ventricle can also occur when there are 2 well formed anatomic ventricles, some examples are?

Answer 53

- Tetralogy of fallot - Truncus arteriosus - Severe neonatal aortic stenosis

Question 54

What is the pathophysiology of intercirculatory mixing?

Answer 54

Occurs in the unique situation that exist in transposition of the great arteries