Congenital Heart Defects Flashcards
inciting factors to CHD
Acidosis, sepsis, hypothermia, hypoxia, hypercarbia: force fetal circulation to persist after birth
Most neonates who are critically ill from CHD have one or more of these inciting factors
Most congenital heart defects are the result of _____
genetic predisposition and environmental factors
Environmental factors: drugs, viral infection, maternal diabetes, maternal alcohol abuse
Normal Pressure in Right Atrium and Right Ventricle in newborns vs. children
RA (newborn): 0-4 mmHg
RA (child): 3-6 mmHg
RV (newborn): 65-80/0-6 mmHg
RV (child): 20-30/3-6 mmHg
Normal Pressure in Pulmonary Artery and Pulmonary Vein in newborns vs. children
Pulmonary Artery (newborn): 65-80/35-50 mmHg
Pulmonary Artery (child): 20-30/8-12 mmHg
Pulmonary Vein (newborn): 6-9 mmHg
Pulmonary Vein (child): 6-8 mmHg
Normal Pressure in Left Atrium and Left Ventricle in newborns vs. children
Left Atrium (newborn): 3-6 mmHg
Left Atrium (child): 6-8 mmHg
Left Ventricle (newborn): 65-80/0-6 mmHg
Left Ventricle (child): 90-120/6-12 mmHg
Normal Pressure in aorta newborns vs. children
Newborn: 65-80/45-60 mmHg
Child: 90-120/50-60 mmHg
PA wedge = ____
pulm venous pressure= LA if no obstruction
What decreases pulmonary vascular resistance?
Hypocapnia
Pulmonary vasodilator (nitric oxide)
What increases SVR?
sympathetic stimulation
vasoconstrictor
hypothermia
What increases pulmonary vascular resistance?
hypoxemia
hypercapnia
high hematocrit
positive pressure ventilation
metabolic acidosis
alpha-adrenergic stimulation
What decreases SVR?
vasodilators
spinal and epidural anesthesia
deep general anesthesia
hyperthermia
What is the normal PVR to SVR ratio?
1:10-1:20
If SVR increases relative to PVR then ___ happens
pulm BF increases resulting in decrease systemic BF
If PVR increases relative to SVR then ___ happens
pulm BF decreases resulting in increase in systemic BF
What condition(s) are associated with increased pulmonary blood flow?
- atrial septal defect
- ventricular septal defect
- patent ductus arteriosus
- atrioventricular canal
(all of which are acyanotic lesions)
What condition(s) are associated with obstruction to blood flow from ventricles?
coarctation of aorta
What condition(s) are associated with decreased pulmonary blood flow?
Tetralogy of Fallot
What condition(s) are associated with mixed blood flow?
Transposition of Great Arteries
Hypoplastic Left Heart Syndrome
What are lesions that increase pulmonary blood flow?
Acyanotic Lesions:
-Atrial Septal Defect (ASD)
-Ventricular Septal Defect (VSD)
-Patent Ductus Arteriosus (PDA)
-Atrioventricular Canal Defect
Cyanotic Lesions:
-Transposition of the Great Arteries (TGA)
Atrial Septal Defect is a communication between ___.
What kind of shunt is it?
the LA and RA due to a defect in the intra-atrial septum
L to R shunt
ASDs are classified by ____.
location
Ostium secundum β comprise 80% of ASDs
Ostium Primum- 15 % of ASDβs
Surgical Therapy:
Primary, patched, or device closure
Anesthesia Management:
Inhalation induction tolerated well
Ventricular Septal Defect (VSD) allows communication between ____.
?Types
RV and LV
Types:
Subpulmonary or supracristal defects
Membranous or perimembranous defects- approximately 80% of all VSDs
Muscular defects
With VSD, what impacts the size of the defect?
Size of the defect = magnitude of shunting
Small= restrictive
Large=non-restrictive
Shunt depends on PVR to SVR ratio
Normally, VSD produce L -> R shunt
If PVR to SVR ratio is higher then near normal pulmonary BF resulting in R -> L shunt (Eisenmenger syndrome)
Surgical Treatment of VSD
Surgical Therapy
Large VSDs are corrected early in childhood
Device, patch, or stitch closure
Post-op risk of EKG changes secondary to edema or sutures (Complete heart block, junctional, junctional ectopic tachycardia (JET))
Patent Ductus Arteriosus connects _____.
What kind of shunt is it?
the main pulmonary trunk with the proximal descending aorta
10 % of all congenital heart defects
Girls > boys
L to R shunt
PVR:SVR ratio dependent when PDA is large
Treatment of Patent Ductus Arteriosus
Indomethacin infusion
Closure in catheterization lab
Surgical Therapy
Ligation via left thoracotomy or video-assisted thorascopic surgery
First closure of PDA done at BCH with Robert Gross (surgeon) and Betty Lank (nurse anesthetist) in 1938
**At risk for injuring recurrent laryngeal nerve
Atrioventricular Canal Defect is communication between ____.
all four chambers as well as abnormalities of mitral and tricuspid valves
Partial Atrioventricular Canal Defect
ASD with AV valve rings are complete and separate
Transitional Atrioventricular Canal Defect
partial fusion of endocardial cushions with variable AV valve abnormalities
Complete Atrioventricular Canal Defect
incomplete AV valve rings, ASD, VSD
Surgical Therapy for Atrioventricular Canal Defect
Septation of common AV valve tissue to make 2 separate tricuspid and mitral valve
Closure of ASD
Closure of VSD
Anesthesia Management for ASD VSD AVC and PDA
Maintain HR, contractility, and preload to maintain CO
Airway Management and immediate control of ventilation
Avoid decreases in PVR:SVR ratio
Avoid decreases in PVR or increase in SVR
A decrease in PVR results in increase pulmonary BF so will need increase in CO to maintain systemic BF
Avoid large increases in PVR:SVR ratio (an increase may result in R to L shunt)
How does anesthesia management change if a R to L shunt exists?
Decrease PVR via ventilatory changes
Maintain or increase SVR
Avoid Air-in-line
Premeds and Maintenance for ASD VSD AVC and PDA
0.5 β 1 mg/kg Midazolam PO +/- 3 -5 mg/kg Ketamine PO
0.05-0.1 mg/kg Midazolam IM + 3-5 mg/kg Ketamine IM
βGentleβ Inhalation induction tolerated well
Maintenance on Isoflurane
Inotropic choice is Dopamine (3-10 mcg/kg/min)
Anesthesia Management for Non-cardiac surgery - ASD, VSD, AVC, PDA
Heavy premedication to reduce need for high concentration inhaled agent for induction
Airway management by a skilled provider
Control of ventilation to maintain PaCO2 35-40mmHg
Fentanyl IV 1-2 mcg/kg IV
Rocuronium standard intubating dose 0.6 mg/kg IV
If preload is of concern: bolus with 5-10 mL/kg NS; albumin 5% 10-20 mL/kg
If contractility is of concern: Dopamine infusion
Consider 2nd IV line
If afterload is of concern: Manage PVR:SVR ratio with inotropic support and ventilatory control
Transposition of Great Arteries is ______.
concordance of the atrioventricular connections associated with discordance of the ventriculoarterial connections
More info on Transposition of Great Arteries
Clinical Presentation?
The most common type is D-TGA
Pulmonary and systemic circulation are in parallel
Clinical presentation:
Larger size and weight at birth
Dyspnea and cyanosis
Progressive hypoxemia
Congestive heart failure-HR, Increase RR, Increase in WOB
Metabolic Acidosis- lack of O2 cause tissues to have less O2
Dextro-TGA
Aorta emerges from RV
Pulmonary Artery emerges from LV
Hole or defect in ventricular septum
Hole or defect in atrial septum
Patent ductus arteriosus
Levo-TGA
Congenitally corrected transposition
Aorta and Pulmonary Artery are switched
Ventricles are switched with their corresponding AV valves
Management of Transposition of the Great Arteries
Continue Prostaglandin E1 infusion to maintain patency of DA
Decrease PVR, but maintain SVR
Atrial septostomy (Balloon or surgical)
Repair within the first days to weeks of life
Atrial Switch- atrial venous baffle created
Mustard or Senning
Arterial Switch- Ao/PA transposed, coronaries reimplanted
Rastelli Procedure- VSD closed, baffle created to connect LV to Ao, RV/PA conduit
Lesions that Decrease Pulmonary Blood Flow
Tetralogy of Fallot
Pulmonary Atresia/(IVS)
Pulmonary Stenosis
Tricuspid Atresia
Ebsteinβs Anomaly
Tetralogy of Fallot (TOF) is characterized by which 4 distinct defects?
- PS, 2. RV Hypertrophy, 3. Large VSD, 4. Overriding Aorta
fixed and dynamic components of TOF
Fixed: pulmonary stenosis
Dynamic: is found subvalvular produced by variations in the caliber of the RV infundibulum
Together this creates severe RVOTO- R to L shunt
Management of Tetralogy of Fallot
Heavy premedication PO or IM
0.5 β 1 mg/kg Midazolam PO +/- 3 -5 mg/kg Ketamine PO
0.05-0.1 mg/kg Midazolam IM + 3-5 mg/kg Ketamine IM
After heavy premedication, gentle inhalation induction is tolerated
Airway Management and immediate control of ventilation
Maintain HR, keep PVR down, and SVR up; avoid severe R to L shunt
No air-in-line
Treatment for Tetralogy of Fallot
Palliative systemic to pulmonary arterial shunt: Waterston and Potts, Central shunt, Blalock-Taussig shunt
Definitive repair: Resection of hypertrophied RVOT to enlarge OT, closure of VSD
Blalock-Taussig Shunt
Proximal end of SCA is sewn to the side of the PA
Classic or Modified approach
Inaccurate BP on shunt arm!! (put BP cuff on opposite arm. If cuff on same side as shunt it will be inaccurately low)
Blalock-Taussig Shunt
O2 sats 70-80%
Avoid dehydration-volume support
Low FIO2, RA if possible
Too much pulm BF leads to decreased CO
Treatment for hypoxic Tet Spells
Administer 100% O2
Knees to chest position
Morphine (0.05-0.1 mg/kg) IV
Crystalloid 15-30 mL/kg to enhance preload
Sodium Bicarb (1-2mEq/kg) to treat severe metabolic acidosis
πΌβπππππππππππ : Phenylephrine (5-10 ππ /kg) bolus or (2-5 ππ /kg/min) infusion
π½βπππππππππππ : Contraindicated as increasing contractility will narrow the stenosis
Propanolol (0.1mg/kg) β may reduce infundibular spasm and slowing HR may improve preload
ECMO
Lesions Obstructing Systemic Blood Flow
Coarctation
Hypoplastic Left Heart Syndrome (HLHS)
Interrupted Aortic Arch
Aortic Stenosis
Coarctation of the Aorta is _____
a focal narrowing of the aorta
Represents 6-8% of congenital heart defects
More commonly found in males and most common lesions in patients with Turner syndrome
Produces LV pressure overload and decreased in lower body perfusion
Clinical Signs of Coarctation of the Aorta in Neonates
Severe congestive heart failure
Weak or absent lower extremity pulses
4 extremity BP gradient
CXR shows increased pulmonary vascular markings, cardiomegaly
Clinical Signs of Coarctation of the Aorta in Older Children
Usually asymptomatic
Weak pulses in lower extremity
Pain or weakness in legs with exercise
Hypertension
CXR: LV hypertrophy, rib notching
Treatment for Coarctation of the Aorta
Surgical Repair
End to end repair
Patch Aorto-plasty
Goals for management of Coarctation of the Aorta
Maintain HR, contractility, preload to maintain CO
If there is ASD or VSD, avoid reduction in PVR:SVR ratio
Avoid increases in SVR
A-line in the R arm
Management of a sick neonate with coarctation of the aorta
PGE1 (0.05-0.1 πg/kg/min) infusion to reestablish ductal patency
Mechanical Ventilatory and inotropic support
Diuretic
Treatment of metabolic acidosis
May suffer transient renal and hepatic dysfunction
Postop Consideration for Coarctation of the Aorta
Cross- clamping risk
Risk for NEC
Spinal cord ischemia
Recurrent coarctation (10-30% risk)
Re-operation
Balloon dilation in cath lab
Hypoplastic Left Heart Syndrome is characterized by ____
an underdeveloped LV and very small Aorta
Survival of Hypoplastic Left Heart Syndrome is dependent on ____
R to L shunt through PDA for adequate perfusion
L to R shunt at atrial level for adequate saturation: restrictive ASD
Distal Ao arch flow occurs via the PDA. Proximal Ao BF and coronary BF occur by retrograde filling of a tiny ascending Aorta via PDA- this puts HLHS at high risk for myocardial ischemia.
PGE1-PDA patency is life saving
During HLHS repair, what are the 3 main goals?
- reliable source of pulmonary blood flow, 2. unobstructed delivery of pulmonary venous blood to systemic ventricle, 3. unobstructed path from systemic ventricle to aorta
Surgical Repair of Hypoplastic Left Heart Syndrome
Surgical Repair
3 Stage Palliation
Stage 1 Norwood or Sano- within 1st week of life
Stage 2 bi-directional Glenn (SVC end to side anastomosis to branch PA)- 3-6 months of life
Stage 3 Fontan β 2-3 years of age
Heart Transplantation
Staged Repair for HLHS
HLHS
Initial Repair involving atrial septectomy, Damus-Kaye-Stansel (DKS) anastomosis of main PA to Ascending Ao, homograft augmentation of aortic arch, r-modified Blalock-Taussig shunt (BTS), to supply pulmonary BF
Initial Repair involving atrial septectomy, DKS, homograft augmentation of aortic arch, RV to PA conduit to supply pulm BF
Superior cavopulmonary shunt (bidirectional Glenn)
Fontan procedure
Bi-directional Glenn
SVC is removed from heart and connected end to side to the Right pulmonary artery, which is in continuity with the Left pulmonary artery. The main PA has been separated from the heart and oversewn.
Fenestrated Fontan
with baffle containing fenestration inside RA to connect IVC with RPA with previous BiD Glenn shunt
Extracardiac Fontan
connects IVC to RPA with previous BiD Glenn shunt
HLHS initial management
Provide prostaglandin infusion to maintain PDA patency
Decrease FIO2 delivery: Additional oxygen is not used since it tends to promote more blood flow to the lungs
Possible Intubation- target PaO2 40-45 mmHg and SaO2 of 70-80%
Need adequate CO to provide systemic oxygen delivery- ability to recruit stroke volume with preload is limited d/t volume overloaded single ventricle and increasing HR in ischemic prone heart is not advisable. Dopamine 3-5 ππ /kg/min
HLHS staged repair
Stage 1 75 % survival rate
Stage 2 90 % survival rate
Fontan β dysrhythmias, limited activity due to poor oxygenation, may develop liver and kidney dysfunction
