Pediatric Cardiovascular Surgery (Exam II) Flashcards
Name the normal adult anatomy depicted by 1 in the figure below.
Brachiocephalic Artery
Also called the Innominate Artery.
Name the normal adult anatomy depicted by 2 in the figure below.
Right Subclavian Artery
Name the normal adult anatomy depicted by 3 in the figure below.
Right Common Carotid Artery
Name the normal adult anatomy depicted by 4 in the figure below.
Left Common Carotid Artery
Name the normal adult anatomy depicted by 5 in the figure below.
Left Subclavian Artery
What limits blood flow to the lungs in the neonate?
High PVR
What vessels bypass pulmonary circulation in neonates?
Foramen Ovale & Ductus Arteriosus
What vessels are connected via the ductus arteriosus?
Pulmonary Artery & Aorta
What is the purpose of the Ductus Venosus?
The DV allows for maternal blood going to the fetus to be shunted past the liver directly into the Vena Cavae.
Fetal Circulation Diagram
What are the three major changes that occur with fetal circulation at birth?
- ↓PVR
- ↑ blood flow through pulmonary veins
- Placental flow ceases
What occurs with neonatal alveolar PCO₂ and PO₂ at birth?
- PCO₂ decreases
- PO₂ increases
occurs within minutes.
What occurs due to the massive decrease in PVR at birth?
Blood flow moves through previously low flow pulmonary veins.
What occurs between Left Atrial Pressure (LAP) & Right Atrial Pressure (RAP) as a neonate is born?
- LAP exceeds RAP and forces closure of Foramen Ovale
Why should air in venous access be avoided in children under the age of 5?
50% of children in this age group still have a patent Foramen Ovale.
What occurs with SVR as a neonate is born?
SVR increases
What occurs with Vena Cava flow as a neonate is born?
Vena Cava flow decreases
What occurs with right atrial pressure as a neonate is born?
RAP decreases
What occurs with DA flow as a neonate is born?
DA flow reverses and fills with oxygenated blood.
The DA is mostly closed by ____ after birth.
two days
How long does the DV remain patent after birth?
several days
What is the consequence of a patent DV in a neonate needing surgery the day after being born?
Drug metabolism is delayed due to blood flow still shunting away from the liver.
What two factors cause closure (constriction) of the DA?
- ↑ PaO₂
- Loss of Prostaglandins
*
What can occur if hypoxia occurs immediately after birth?
PVR can increase & FO & DA may reopen.
What is the clinical consequence of reopening FO & DA?
Hypoxia worsens (due to blood bypassing lungs)
What conditions can prolong transitional circulation?
In the neonate, is the RV or the LV thicker?
RV
What is the electrical consequence of a neonate having a thickened RV?
180° axis
Why are neonates rate dependent for CO?
Cardiac tissue is less contractile (inability to change SV).
What are the consequences of neonates having immature myofibrils and sarcoplasmic reticulums?
- Sensitivity to CCBs & citrated PRBCs
- Ca⁺⁺ exchange more dependent on sarcolemma
- Ca⁺⁺ replacement more necessary than in adults.
What is the consequence of neonates having immature autonomic innervation?
Inability to respond to stress (fever, acidosis, etc.)
Left to Right shunts are known as ______ shunts.
Acyanotic
Name examples of Left-to-Right shunts.
- ASD
- VSD
- PDA
- Coarctation of the Aorta
What is the PVR in Acyanotic shunts?
↓PVR
What is the consequence of low PVR in Left-to-Right shunts?
- Pulmonary blood flow increases
- Pulmonary volume overload
- ↑ LV workload (CHF?)
What should be avoided in left-to-right shunts?
- Vasodilators
- 100% FiO₂
- ↓ PCO₂
- Alkalosis
What are the hemodynamic features of a Left-to-Right shunt?
- ↑ pulmonary perfusion
- ↓ CO
- ↓ BP
- LV overload
Cyanotic shunts are also known as _______ shunts.
Right-to-Left
Why do Right-to-Left shunts occur?
PVR or Pulmonary outflow tract pressure > than SVR.
What are the features of Cyanotic shunts?
- ↓ Pulmonary Blood Flow
- Deoxygenated blood in circulation
- Systemic Hypoxia
- RV failure
What are examples of Cyanotic shunts?
- TOF
- Transposition
- Truncus Arteriosus
- Hypoplastic Left Heart
What should be avoided in Right-to-Left shunts?
- SNS stimulation
- ↓ FiO₂
- ↑ PCO₂
- Acidosis
How will an inhaled induction change when comparing a patient with Right-to-Left vs a patient with Left-to-Right shunt?
Right-to-Left
- Prolonged inhaled induction
Left-to-Right
- Normal inhaled induction
Why are inhaled inductions slower in Right-to-Left shunt patients?
Blood is bypass lungs thus slower uptake of VAA.
What type of cardiac defect is defined as having pulmonary & systemic O₂ saturations that are almost identical?
Mixing lesions
What is an example of a mixing lesion?
Truncus Arteriosus
What are examples of obstructive lesions?
- Aortic Stenosis
- Coarctation of the Aorta
What is the hemodynamic result of severe obstructive lesions?
Overloaded ventricle just proximal to the lesion.
- Profound ventricular failure
- Impaired coronary circulation
- Systemic ↓BP
- Hypoxemia
Obstructive lesions require the _____ to provide systemic flow.
PDA (patent ductus arteriosus)
Why does PVR decrease so quickly after birth?
Due to Lung expansion & oxygenation
Infant PVR has reach adult pressure levels by ____ of age.
6 months
What things increase PVR?
- PEEP
- Atelectasis
- ↓ FiO₂
- Acidosis
- ↑ H/H
- ↑ SNS
- Direct surgical stimulation
- Vasoconstrictors
What things decrease PVR?
- Low airway pressures
- Lung expansion to FRC
- ↑ FiO₂
- Alkalosis
- ↓ H/H
- Deep Anesthesia
- NO
- Vasodilators (milrinone, PG’s, etc.)
NO is a _______ pulmonary vasodilator.
selective
What is the typical inhaled NO dose?
20 - 40 ppm
Why should NO be discontinued slowly?
Abrupt discontinuation can cause rebound pHTN.
Patent Foramen Ovale is a subtype of Atrial Septal Defect. T/F?
True
Watch video on the different types of Atrial Septal Defect
What is the most common congenital defect?
VSD’s
20% of congenital heart defects
What are the two types of VSD?
- Restrictive: small defect
- Unrestrictive: large defect
How does monitoring change for PDA repairs?
- Two pulse oximeters (one on right hand and one on left foot)
If your left foot pulse oximeter loses its reading during a PDA repair, what would the CRNA expect?
Aorta may be clamped
What is the most common cyanotic heart defect?
Tetralogy of Fallot
What are the four components of ToF?
- VSD
- Overriding Aorta
- RV outflow obstruction
- RV Hypertrophy
What are TET spells?
Episodes where stress (crying, feeding, acidosis, surgical stimulation) causes epidoses of hypercyanosis & worsening RV outflow obstruction.
What are components of anesthesia for TOF repair?
- Preop sedation (to prevent TET spells)
- 100 FiO₂
- β blockade
What option (other than complete repair) is there for TOF patients?
Blalock-Taussig Shunt
Systemic-Pulmonary shunt
- From subclavian artery to branch pulmonary artery.
What are the components of Transposition of the Great Arteries? (ToGA)
- Aorta comes off the RV
- Pulmonary Artery comes off the LV
- Some mixing via PDA or VSD
What allows for a patient with ToGA to live despite this defect?
Oxygenated blood mixing via PDA or VSD
What would indicate an urgent/emergent repair of ToGA?
ToGA w/ no VSD (no mixing = no oxygenation)
What are the features of Truncus Arteriosus?
- Fusion of PA & Aorta
- Common valve between PA & Aorta
- Large VSD
Truncus Arteriosus is associated with what syndrome?
DiGeorge Syndrome
Besides DiGeorge syndrome, what other abnormalities are associated with Truncus Arteriosus?
- Aortic Arch issues
- Absent parathyroids
- Immune deficiency
What are features of Hypoplastic Left Heart Syndrome? (HLH)
- Hypoplastic LV
- Mitral Stenosis/Atresia
- Aortic Stenosis/Atresia
- Hypoplastic Aortic Arch
- ASD
An HLH patient’s sats are typically in the _____.
80%’s
Patients who survive past the age of 5 with HLH eventually require ______.
Heart Transplantation
What are the goals of HLH anesthesia?
- Balance PVR and SVR
- PaCO₂ normal
- Keep FiO₂ very low
