Congenital Heart Disease Flashcards
Photo of fetal circulation (maybe a hot spot Q?)
The Placenta is a large low resistance vascular bed – PVR > SVR
CO is combined ventricular output, the RV is thicker and has 2/3rds of output, and LV is only 1/3rd
3 shunts of the fetal heart
- Ductus Arteriosus
- Foramen Ovale
- Ductus Venosus
Ductus Arteriosus
largest vessel – protects the lungs against circulatory overload –> RV strengthens which increases pulmonary vascular resistance and decreases blood flow
- should close within 24 hours of birth, yet can take 2 -3 weeks
How to close or keep ductus arteriosus open
Small opening: prostaglandin inhibitors (Indamethacin) to close … larger = surgery
if baby needs the shunt to get O2 rich blood –> PGE1 and bradykinin to KEEP DILATED
meconium aspiration
would continue PVR increase and fetal circulation to persist –> PULM HTN –> ECMO
worsened with hypoxia, acidosis, and hypothermia
Newborn Heart- Foramen Ovale
function: to shunt highly O2 rich blood from the RA to the LA
- Functional closure occurs in the first few hours after birth as the LAP > RAP
Probe patent foramen ovale = PFO
- 50% of 5 year olds
- 25% of 20 year olds
CONCERNED about: Paradoxical embolus
to prevent … SVR > PVR
Ductus Venosus
Connects the umbillical vein to the inferior vena cava … flow is regulated though a eustachian valve
Fetal Blood Flow
Blood enters from two areas: the IVC and SVC …
IVC from Moms blood (more O2) and SVC replies on patent foramen ovale and ductus arterosis d/t mixing of blood
Fate of Shunts
First few days –> weeks is unstable circulation, PVR is still increased yet sensitive to changes
1st breath will DECREASE PVR
HPV is marked
PVR normalizes in 6wks ~ adult
Newborn heart- Ventricular tissue
Fewer myocytes - 30%
Greater proportion of connective tissue
Relative RVH
- Decreased compliance
- More sensitive to preload
Ventricular interdependence
- Relatively noncompliant
- Relatively restricted in ability to change SV
- Cardiac output is more rate dependent
- By age 2-3 yrs CV system essentially that of a fit adult
Autonomic Nervous System
PNS essentially complete at birth
SNS innervation of heart and vasculature incomplete - more bradycardia esp with stress (hypothermia, hypoxia, and acidosis)
Greater dependence on adrenal-circulating catecholamine system
Vagal tone predominates
normal neonate pressures
PEARLs about the preterm infant heart
More sensitive to depressant effects of inhaled agents - CO can decrease
Decreased responsive to catecholamines
Relatively high PVR persists
Pulmonary vasculature more sensitive to vasoconstriction by
* Hypoxia
* Acidosis
* Hypercarbia
Acyanotic Lesions
L – R shunt
Atrial septal defect (ASD)
Ventricular septal defect (VSD)
Atrioventricular Septal defect (AV Canal)
Patent ductus arteriosus (PDA)
Types of Atrial Septal Defects
1 Secundum ASD – at the Fossa Ovalis, most common.
There are 3 major types:
ASD Clinical Signs & Symptoms
Rarely presents with signs of CHF or cyanosis
Increased fatigability
Mild failure to thrive, can’t suck well
May have associated pulmonary hypertension –>cyanosis
Hyperactive precordium – RV heave – fixed split S2
II-III/VI systolic ejection murmur @LSB
Mid-diastolic murmur @LLSB
- afib if overloaded d/t stretch of atrial fiber muscles
Treatment of ASD
Surgical or Cath closure for secundum ASD with Qp:Qs (flow) ratio > 2:1
Closure performed electively 2-5 years
Surgical correction earlier in children with CHF or pulmonary hypertension
Mortality <1%
Ventricular Septal Defect Types
- Perimembranous (or membranous) – Most common.
- Infundibular (subpulmonary or supracristal VSD) – involves the RV outflow tract.
- Muscular VSD – can be single or multiple.
- AVSD – inlet VSD, almost always involves AV valvular abnormalities.
VSD Signs and Symptoms
Elevated RV & Pulmonary pressure
Hypertrophy
Small – moderate VSD usually asymptomatic – 50% will close by 2 years
Moderate – large VSD – symptomatic – surgical repair
II-III/VI harsh holosystolic murmur @ LSB
Prominent P2 – diastolic murmur
CHF – Respiratory failure
seen from birth - 6 mo.
VSD Treatment
Small = no surgical intervention
Symptomatic = initial medical treatment with diuretics and afterload reducers
Surgical closure
Large VSD
Ages 6 – 12 mos. large VSD & pulmonary HTN
Ages > 24 mos. With Qp:Qs ratio > 2:1
Supracristal VSD of any size (aortic valve involvement)
Atrioventricular Septal Defect
Complete
Low primum ASD continuous with posterior VSD
Cleft in both septal leaflets of TV/MV
Large L – R shunt
TR/MR – pulmonary HTN
Incomplete
Primum ASD with cleft in MV & small VSD
Hemodynamics are dependent on lesion
AVSD – Signs & Symptoms
Incomplete may be indistinguishable from ASD
CHF
Recurrent pulmonary infection
Failure to thrive
Easy fatigability
Late cyanosis from pulmonary vascular disease w R to L shunt
Hyperactive precordium
Accentuate 1st heart sound
Wide splitting of S2
Pulmonary systolic ejection murmur w/thrill
Holosystolic murmur at apex w/radiation to axilla
Mid-diastolic rumbling murmur @ LSB
Marked cardiac enlargement on CX-ray
AVSD Treatment
Treat CHF symptoms
Surgery is always required
Pulmonary banding may be required in premature infants or infants < 5Kg
Mortality low w/incomplete 1 – 2%
Mortality w/complete 5%
Patent ductus arteriosus (PDA) Signs and Symptoms
Small - asymptomatic
Large – may have symptoms of CHF – FTT – growth retardation
Bounding arterial pulses
Widened pulse pressure
Enlarged heart – prominent apical impulse
Continuous systolic murmur
Mid-diastolic murmur at apex
PAP = systolic pressures with larger PDA
PDA associated infections?
TORCH
Toxoplasmosis
Other: syphilis, varicella-zoster, parvovirus)
Rubella
CMV
Herpes
PDA Treatment
Indomethacin (Prostaglanin inhibitor)
Surgical or catheter closure
- Ligation & division
- Intravascular coil
- Mortality is <1%
Cyanotic Lesions
R –> L shunt … body-body
Tetralogy of Fallot
Total anomalous pulmonary venous return
Truncus arteriosus
Transposition of the great arteries
Tricuspid atresia
Hypoplastic left heart syndrome (also obstructive)
TOF
most common right obstructive lesion
- RV hypertrophy
- overriding aorta with mixed blood
- R –> L shunt
- PVR > SVR and diminished pulmonary blood flow
- cyanotic, no murmur
may have aortic ejection click
Tetralogy of Fallot:
Preoperative Preparation
Heavy premedication
Consider IM ketamine or inhalation induction but get rapid control of airway. (crying worsens hypoxia)
Keep SVR up and PVR down, maintain heart rate
Intraoperative TEE
Oral premed/induction
midazolam + ketamine
Tetralogy of Fallot:
Perioperative concerns
Increase in PVR or decrease in SVR leading to Right to Left shunt
Tet Spells pre induction (crying/anxiety)
Polycythemia and bleeding - (polycythemia d/t kidneys sensing hypoxia, releasing more erythropoietin to make more RBCs)
Air embolus
RV failure (d/t pulmonary pressures being high and volume overload)
Total Anomalous Pulmonary Venous Return (TAPVR)
Pulmonary veins do NOT return back to LA
TYPES:
“Supra” cardiac : Pulm veins attached to Superior Vena cava
“Infradiaphragmatic” : pulm veins – inferior vena cava
“Intra-cardiac”: pulm veins - RA
“Mixed” L veins to supra, and R veins to infra
Truncus Arteriosus
Aortic and Pulmonary artery are ONE single vessel… VSD is essential for oxygenated blood –> brain and body
Tricuspid atresia
- More than 70% patients are severely cyanosed due to inadequate pulmonary flow through the PDA
- Need a systemic to pulmonary shunt: Variety used, most common Fontan
- Where pulmonary flow is high the PA is banded; Assessment of RV function is important here
- Definitive repair leads to a cavopulmonary anastamosis (Fontan) and this is sometimes two staged, i.e. Hemi-Fontan or Bidirectional Glenn being the intermediary stage.
- Patients present for BT shunt often on PGE1
- Meticulous airway management is key to maintain flow balances
Hypoplastic Left Heart Syndrome
cyanotic and obstructive disease – blood flow via PDA (keep on PGE1s)
- also have aortic atresia, LV and mitral valve hypoplastic
pulmonary over circulation
- inadequate systemic circulation
- PULM HTN
Pulmonary Stenosis
Pulmonary to System Flow Ratio
