CV In Pediatric Population Flashcards
1
Q
What is the anesthetic implication of infant HR control maturing before B-adrenergic control?
A
- Infants are more apt to become bradycardic
- May not respond to hypovolemia or light anesthesia with tachycardia (Immature SNS)
2
Q
What is the anesthetic major anesthesia concern of succinylcholine administration of the neonate?
A
- A vagotonic response that may lead to bradycardia and/or asystole
- Immature SNS
- Can also happen with opioids
- OFFSET BY ATROPINE (OPPOSE PNS)
- PEDS: EXAGGERATED RESPONSE TO SUCCINYLCHOLINE, ALWAYS DRAW ATROPINE!!!!
3
Q
What is the organ of prenatal respiration?
A
- The placenta
4
Q
With fetal circulation bypassing the lungs, what are the three special shunts that allow perfusion to the heart and brain?
A
- Ductus venosus
- Foramen Ovale
- Ductus arteriosus
5
Q
Due to increased pulmonary vascular resistance (secondary to pulmonary hypoxia), and patency of the ductus arteriosus and foramen ovale. What percentage of blood flow actually crosses pulmonary circulation?
A
- Only 10%
- 90% bypasses pulmonary circulation via the foramen ovale and ductus arteriosus
6
Q
Describe the path of oxygenated blood from the placenta through fetal circulation
A
- Umbilical vein
- Ductus venosus
- Inferior vena cava
- Right atrium
- Foramen ovale
- Left atrium (cerebral circulation)
- Remaining right ventricle output goes through ductus arteriosus (systemic circulation)
7
Q
Where are the origin and role of the two umbilical arteries?
A
- Internal iliac arteries
- Return UNOXYGENATED BLOOD to the placenta
8
Q
What is the role of the umbilical vein? What is the typical Pa02 of blood in the umbilical vein?
A
- Carry OXYGENATED blood from placenta to fetus
- 60-70%
9
Q
How would you characterize vascular resistance in fetal circulation and why? Pulmonary vascular resistance and why?
A
- Low SVR, secondary to low-resistance placenta
- High PVR, secondary to fluid-filled lung and hypoxic pulmonary vasoconstriction
10
Q
What is the functional role of the ductus venosus and foramen ovale?
A
- Circulate the most oxygenated blood from umbilical vein to the brain and heart
- DV bypasses liver
- FA bypasses RV
11
Q
Where is pre-ductal Sp02 measured?
A
- Right hand
12
Q
Where is post-ductal Sp02 measured?
A
- Feet
13
Q
What is the result that high PVR has on the majority of RV output?
A
- Forces RV output across the ductus arteriosus into the descending aorta
- Allows deoxygenated blood to return to the placenta
14
Q
What is maternal Pa02? Umbilical vein 02? Blood ejected from LV in the fetus?
A
- 100
- 30-35
- 25-30
15
Q
What three factors act to decrease PVR in transitional circulation?
A
- Lungs expand to normal FRC when air enters lungs
- Marked reduction in PaC02
- Increase in Pa02
16
Q
What factor results in functional closure of the foramen ovale?
A
- LVED pressure surpasses RA pressure
- FUNCTIONAL closure occurs within minutes
17
Q
What percentage of adults will remain with a patent foramen ovale?
A
- 25-30%
18
Q
When does anatomic closure of the foramen ovale occur?
A
- Months
19
Q
When does the FUNCTIONAL closure of the ductus arteriosus occur?
A
- Day 4 of life in 98% of infants
- Initial constriction occurs with increase in arterial oxygen tension
20
Q
When does ANATOMIC closure of the ductus arteriosus occur?
A
- 2-3 weeks after birth
21
Q
When does FUNCTIONAL closure of the ductus venosus occur?
A
- Right away
- Ligation of the umbilical vein drops portal pressure and triggers closure
- Anatomic closure takes 1-2 weeks
22
Q
What changes occur in the LV in the transitional circulation?
A
- RV and LV are the same size at birth
- LV takes over volume workload
- LV hypertrophies and is twice as heavy as RV by 6 months
23
Q
What occurs if PVR exceeds SVR? And what is the major concern with this development?
A
- A right-to-left shunt can develop via the ductus arteriosus
- Produces life-threatening hypoxemia
- May require NO or ECMO to sustain life
24
Q
What is the net result of persistent fetal circulation?
A
- A right-to-left shunt
25
What are the major characteristics of the neonatal CV system in comparison to adults?
- Contractile myocytes are 30% in the neonate, 60% in adults
- More reliant on Ca+ influx to initiate and terminate contraction
- CO is increased, high metabolic rate
- Increased sensitivity to negative inotropic and chronotropic drugs
- Immature SNS, and mature PNS predisposes neonate to exaggerated vagal responses
26
Describe pulmonary vascular development of the neonate?
- Matures during the first few years of life
- PVR decreases due to lung expansion and increased oxygenation
- Certain pathophysiologic conditions lead to increased PVR, right-to-left shunt may develop via ductus arteriosus
- Will lead to PATENT DUCTUS ARTERIOSUS
27
What four conditions can develop into PERSISTENT FETAL CIRCULATION?
- Hypoxia
- Hypercarbia
- Acidosis
- Shock
28
What are the anesthetic implications of administering midazolam to the neonate?
- WELL TOLERATED IN CHILDREN WITH CARDIAC DISEASE
| - CAN DECREASE CO WHEN COMBINED WITH MORPHINE
29
What are the anesthetic implications of administering inhaled anesthetics to the neonate?
- ALL INHALED ANESTHETICS ARE MYOCARDIAL DEPRESSANTS
30
What are the anesthetic implications of administering opioids to the neonate?
- HIGH CV STABILITY, EVEN AT HIGH DOSES
- MINIMAL EFFECT ON HR, CO, PVR, MAP, AND SVR
- MAY BE USED AS THE SOLE AGENT
31
What are the anesthetic implications of administering Propofol to the neonate?
- Can decrease BP and HR
32
What are the anesthetic implications of administering Ketamine to the neonate?
- Sympathomimetic action preserves myocardial function
| - Is actually a myocardial depressant and this effect manifests when catecholamines are depleted
33
What are the anesthesia concerns with regional anesthesia of the neonate?
- Spinal and epidurals have minimal hemodynamic effects compared with the vasodilation in adults
- Fluid loading not required
- Negligible hemodynamic effects
34
What is the occurrence of congenital heart disease (CHD)
- 7-10 in 1,000 live births
- 30% of all congenital diseases
- 2/3 of lesions are found in children trisomy-21
35
What is the process by where venous return into one circulatory system is recirculated through the arterial outflow of the same circulatory system?
- Shunting
| - (Shunting is necessary w/ transposition of the great vessels)
36
What occurs when there is complete mixing of pulmonary and systemic venous blood at the atrial or ventricular level?
- Single ventricle
37
What occurs in a single ventricle pathology when a patent ductus arteriosus is the sole source of systemic blood?
- Ductal dependent circulation
38
What are 3 congenital heart defects that occur with 2 well-formed anatomic ventricles and rely on ductal dependent circulation?
- Tetralogy of fallot
- Truncus arteriosus
- Severe neonatal aortic stenosis
- All require VSDs for circulation
39
What is the unique situation that occurs in the transposition of the great vessels where two independent circulatory systems form and rely on a PDA and/or VSD?
- Intercirculatory mixing
40
What is the importance of a CBC in a cyanotic child?
- Will determine:
- Polycythemia
- Microcytic anemia
- Thrombocytopenia
41
What commonly used sympathomimetics in adults is contraindicated in neonates?
- Norepinephrine
- Ephedrine
- Phenylephrine
42
What are the emergency drugs that need to be available in children with severe cardiac disease?
- Atropine 0.01mg/kg-0.02mg/kg
- Epinephrine 0.01mg/kg
- CaCl- 5-20mg/kg
- Lidocaine- 1mg/kg
- Succinylcholine 2-3mg/kg
43
What is the preferred anesthetic technique for the infant with severe CV disease and what is the goal of this technique?
- Intravenous administration
| - Maintain dequate oxygenation and CO
44
With intravenous induction anesthesia, how does a left-to-right shunt effect the speed of induction?
- Slower the speed of induction
| - Drugs recirculate in the lungs, does not go systemically
45
With intravenous induction anesthesia, how does a right-to-left shunt effect the speed of induction?
- Faster induction
| - Drug rapidly enters systemic circulation, enters brain rapidly
46
With inhalational induction anesthesia, how does a left-to-right shunt effect the speed of induction?
- Faster induction
- A functionally low CO output state that "whisks away" less agent from the alveoli, allowing the rate of rise of Fa/Fi to build rapidly
47
With inhalation induction anesthesia, how does a right-to-left shunt effect the speed of induction?
- Slower induction
| - Decreased pulmonary/alveolar blood flow rate of increase of arterial partial pressure of the agent
48
In the neonate with CV disease, anesthesia can be maintained with inhalational or intravenous technique but what is the most common method?
- High dosage opioid technique
49
What is one of the most common CHD in children that manifests with an open foramen ovale? What type of shunt does it create?
- Atrial Septal Defect (ASD)
- Left-to-right shunt
- Pressure in LV higher the RV, shunts blood through PFO back to the right heart
- Increased blood flow to the lungs
- Enlarged right ventricle
- Most common in trisomy-21
50
What is the single most common CHD in children? What type of shunt does it create?
- Ventral Septal Defect
- Normally a left-to-right shunt, pressures in LV higher than RV
- Hemodynamic significance directly r/t size of defect
- Increased blood flow to the lungs
- Enlarged left and right ventricles
51
What is the name of the CHD that consists of a VSD w/ pulmonary hypertension?
- Eisenmenger Syndrome
- Causes non-cyanotic heart disease, Left-to-right shunt
- Eventually, built-up pulmonary congestion builds pressure in the RV and left-to-right shunt becomes right-to-left shunt
- Key S/S:
- Cyanosis
- Clubbing of fingers
- Polycythemia
52
What is the vascular structure that connects the pulmonary trunk and the proximal descending aorta?
- Ductus arteriosus
53
Which CHD is at increased risk in premature infants? And what type of shunt can it produce?
- Patent ductus arteriosus
| - Increased pulmonary blood flow and LV work can eventually develop into PULMONARY HTN
54
Which CHD in the neonate is characterized by a narrowing of the aortic lumen in the thoracic region?
- Coarctation of the aorta
- Often accompanied with other defects (bicuspid aortic valve, VSD, mitral valve abnormalities)
- No obstruction to systemic flow
- Increased LV afterload
- Occurs w/ ventricular dilation and HF in infancy
- LV hypertrophy and arterial HTN proximal to the aortic proximal to aortic obstruction (UE BP will differ from LE BP)
55
What is the most common cyanotic heart lesion? What are the primary characteristics?
- Tetralogy of Fallot
- RV outflow tract obstruction (RVOTO, Infundibular pulmonary stenosis)
- Intraventricular communication (VSD)
- RV hypertrophy (Right-to-left shunt causes hypertrophy)
- Overriding aorta
- RV pressure at systemic levels and PA pressures are low, secondary to pulmonary outflow tract obstruction
56
What causes cyanosis in Tetralogy of Fallot?
- Limited pulmonary blood flow
| - Right-to-left shunt in the VSD
57
What are conditions that increase Right-to-left shunt in TOF?
- Acidosis
- Hypercarbia
- Hypotension
- Decreased SVR
- Increased Afterload
58
What is a controversial aspect of the surgical management of TOF?
- Partial and then early complete repair vs. early complete repair
59
Describe staged repair for TOF?
- Palliation w/ systemic-to-pulmonary shunt FIRST
- THEN Closure of the VSD
- Relief of the RVOTO
60
What are some of the complications after TOF surgical repair?
- RV dysfunction
- Pulmonary regurgitation
- Junctional ectopic tachycardia
61
- 100% 02
- Hyperventilation
- NAHCO3
- Adequate preop hydration
- Decreased PVR and improved pulmonary blood flow
- Treatment of hypercyanotic spells with volume and sedation are all anesthetic management componenets in the treatment of what CHD?
- Tetralogy of Fallot
62
What is an important aspect in the anesthetic management of TOF regarding perioperative HR?
- Avoid increases in HR (Decrease in myocardial rest time and filling time)
- Treat w/ B-Blockers (relaxes infundibular spasm and reduces HR)
- Increased HR exacerbates infundibular pulmonary stenosis
- Remember right-to-left may slow inhalational induction
63
```
What is characterized by:
- Hypercyanotic episodes
- Is caused by decreased pulmonary blood flow w/ significant RVOTO
- Occurs w/ hypovolemia
- Occurs w/ extreme vasodilation?
What is the treatment?
```
- "Tet Spells"
| - Treatment is to increase blood volume, Increase Fi02, Increase SVR (phenylephrine)
64
What kind of induction is most desirable in the anesthesia management of TOF?
- IV Induction
- Ketamine useful
- Fentanyl and Sufentanil blunts SNS during intubation and avoids increases in PVR
- Volume expansion of 10-15mL/kg of albumin of NS
- Give phenylephrine to reverse low 02 saturations
65
The degree of hypoxemia in TOF is dependent on what?
- Degree of RVOTO
| - And SVR (Decreased SVR increases hypoxemia)
66
What are two conditions associated w/ TOF?
- DiGeorge Syndrome
| - Trisomy-21
67
- Vasodilators
- INH Agents
- Histamine release
- Ganglionic blockers
- Alpha Blockers
- AND NITROUS OXIDE!!!!!!!!!!!!!
Are agents that are to be avoided in the management of what CHD? Why?
- Tetralogy of Fallot
| - They decrease SVR or increase PVR
68
- Hypoplastic RV due to an abnormal tricuspid valve
- ASD or PFO
- Enlarged RA
- Are all components of what CHD?
- What type of shunt does this create?
- Ebstein Anomaly
| - Right-to-left shunt (through ASD or PFO)
69
What CHD is characterized by:
- Connection of the aorta to the RV
- Connection of the pulmonary artery to the LV
- Creates to separate circulatory systems
- Transposition of the Great Arteries
70
What is the only way the neonate with Transposition of the Great Arteries can survive?
- Ventral Septal Defect
- Only way for blood mixing to happen
- Even so, surgery has to happen within days
- Done in stages, likely 3
