Case 63 - Congenital Heart Disease Flashcards

1
Q

What are general anesthetic considerations for common congenital cardiac lesions?

A

1) Exctracardiac defects

  • patients with congenital heart disease (CHD) may also have other congenital anomalies like GU tract
  • associated with chromosal anomalies like Down’s (trisomy 21)

2) prevention of air embolism

  • all CHD pts are at risk for air emboli into systemic circulation
  • shunts are bi-directional
  • air embolism can obstruct RVOT and caue a L-R shunt to change into a R-L shunt.

3) Endocarditis prophylaxis

  • dental procedures and procedures involving respiratory tract, skin structures, or musculoskeletal tissues that are infected
  • not needed for GI or GU or flexible bronch procedures
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2
Q

What are some precautions you can take to prevent air embolism in a patient with CHD?

A
  • CHD patients have shunts that are often bi-directional
    • 1) LV has earlier relaxation than RV –> temporary reverse of L-R shunt
    • 2) air in RVOT can reverse shunt due to acute increase in RV pressure
  • Goal = avoid air embolism to enter systemic circulation

Precautions

  • debubble all IV tubing
  • all IV lines connected while free flowing
  • all syringes clear of air
  • air filters on tubing
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3
Q

Which patients with congenital heart disease require endocarditis prophylaxis?

A

1) patients with unrepaired CHD (including palliative shunts and conduits)
2) repaired CHD with proesthetic material or device w/i 6 months of surgery
3) repaired CHD with residual defect at site

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4
Q

What is an atrial septal defect?

A
  • Left to Right Shunting
  • ASD involves a patent foramen ovale
    • LA to RA shunting
  • can go asymptomatic, eventually increase blood flow to right side of heart –> pulm HTN and RV volume overload –> reversal of shunt (eisenmengers synd)

Anesthethic concern –> prevent systemic embolization of air

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5
Q

What is a ventricular septal defect?

A
  • Left to right shunting
  • flow depends on ratio of PVR to SVR
    • if PVR is high and matches SVR –> no shunting occurs
    • if PVR is higher than SVR –> R to left shunting
    • If PVR is less than SVR –> L to Right shunting
  • Problem is 3 fold
    • left to right shunting promotes more blood returning to left side of heart –> Left heart CHF 2/2 to volume overload of LV
    • large L to R shunting promotes more blood to enter right side of heart than systemic circulation (path of least resistence) = systemic underperfusion and CV collapse
    • L to R shunt promotes increase pulmonary blood flow –> increase in PVR –> reversal of shunt
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6
Q

What is patent ductus arteriosus?

A
  • Left to right shunt
  • Aorta shunts blood to pulmonary artery
  • meds to close shunt = prostaglandin inhibitors (indomethacin)
  • surgical closure if indicated
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7
Q

What are anesthetic considerations for L to R shunting lesions?

A

1) Airway Management

  • intubation and mech ventilation
  • infants have chronicially congested lungs due to increase pulm blood flow from L to R shunting

2) Prevent paradoxical air embolism

  • debubble all IV tubing
  • Air filters
  • med syringes with no air

3) Maintain relatively high PVR

  • infants with large PVR have chronically congested lungs due to inc pulm blood flow assoc with shunting
  • high PVR to minimize further pulm congestion
    • least FiO2 necesary for adequate saturation
    • normocarbia or mild hypercarbia
    • Recall - inc O2, alkalosis, hypocarbia = pulm vasodilation

4) prevent significant decrease in SVR

  • If SVR < PVR, then reversal of shunt –>hypoxic blood into systemic circualtion
  • low dose inhaled anes + opioid + ketamine

5) anes induction

  • inhalation induction not affected by L to R shunt
  • IV induction delayed –> more drug returns to lung

6) endocarditis prophylaxis

  • first 6 months after CHD repair
  • repair but residual defect
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8
Q

What is tetraology of Fallot?

A
  • VSD, RVH, pulmonary valve stenosis, overriding aorta
  • Right to Left Shunting
  • symptoms may improve by keeping ductus arterosius open prior to surgical correction (prostaglandin E1).
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9
Q

in TOF, what are hypercyanotic (aka tet) spells and what are goals of tx for tet spells?

A
  • episodes of further increase in right to left shunting
  • caused by severe infundibular spasm
    • induced by decrease venous return
      • decrease pulm blood flow = less blood to be oxygenated
      • decrease LV filling pressure –> promotes more R to L shunting
    • decrease SVR
      • decreases LV pressure, promotes more R to L shunting

Treatment

  • decrease indundibular spasm
    • decrease contracility, HR
    • increase preload
    • increase SVR
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10
Q

How will you prevent tet spells, how will you tx tet spells if it occurs?

A

Prevention

  • beta-adrenergic blockade
    • relaxes cardiac muscle = prevents infundibular spasm
  • avoid hypovolemia
  • avoid SVR reduction
  • maintain adequate anesthsetic depth to prevent infundibular spasm

Tx:

  • 1) decrease contracility and HR
    • Esmolol
  • 2) increase preload
    • fluid bolus
  • 3) increase SVR
    • phenylephrine bolus and infusion
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11
Q

What are anesthetic considerations for right to left shunting lesions with reduced pulmonary blood flow?

A

1) Prevent paradoxical air embolism

  • debubble all IV lines
  • air filters on IV tubing
  • avoid admin medication with air in syringes

2) avoid dehydration

  • results in decrease preload (decrease LV filling pressure) –> promotes further shunting
  • clear liquids until 2 hrs prior to sx
  • IV fluid

3) cardiac

  • maintain SVR (dec R to L shunting)
  • avoid bradycardia
    • CaO2 low 2/2 hypoxemia. To maintain Do2, need to maintain CO (SV x HR)

4) Pulmonary

  • cyanotic and hypoxic patients (R to L shunting)
  • pts with dec pulm blood flow will have V/Q mismatch (dead space ventilation)
  • increase PaCo2 and ETCO2 gradient (since not all of blood undergoes gas exchange in lungs)
  • moderate degree of hyperventilation necessary to maintain normocarbia

5) Induction

  • prolonged with poorly soluble inhalation anes (sevo, des, N2O)
    • b/c dilution from gas exchanged and non-gas exchanged blood –> overall concentration in blood is very low –> very little gets to brain
  • accelerated with IV agents (bypass lungs)
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12
Q
A
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