CVPR Week 9: Pathophysiology of congenital heart disease Flashcards
Objectives
What is the goal of all heart surgery?
- separate the blue and red blood
- relief of obstruction to flow
Congenital heart disease prevalence
- 8/1000 live births have congenital heart disease
- 2-3/1000 will require early cardiac surgery
- ~50% are detected by prenatal ultrasound
Congenital heart disease symptoms at birth
most are asymptomatic at birth but become symptomatic with changes in PVR
How are Congenital heart diseases screened at birth
mandated pulse oximetry newborn screen (pre and pst ductal saturations ( normal < 4%)
Congenital heart disease comorbidity rate
25% of infants with CHD have extracardiac anomalies or chromosomal abnormality
Congenital heart disease recurrence risk
~3-6% if no gene abnormality found
Congenital heart disease subspecialty
Embryology of the heart
Congenital heart disease: congenital defects are caused by?
- abnormal development
- Abnormal growth (in response to flow pattern)
Highest oxygenated blood in the fetal circulation
Umbilical vein
Describe the ductus venosus
Describe streaming of flow in the fetal circulation
Describe foramen ovale
Describe ductus arteriosus in the fetal circulation
Describe the combined cardiac output in the fetal circulation
RV 65% LV 35%
What kind of lesion is a ventricular septal defect?
flow dependent lesion
Ventricular septal defect causes
- decreased flow out of the aorta
- poor growth of the aortic isthmus
Prominent Eustachian valve
- the Eustachian valve is designed to direct IVC flow across the foramen ovale
- If the Eustachian valve is too large it can interfere with SVC flow to tricuspid valve
What is the congenital defect associated with prominent Eustachian valve
Tricuspid atresia
Why does a prominent Eustachian valve lead to another congential heart defect?
the large Eustachian valve can reduce flow from SVC so tricuspid valve does not receive flow to encourage growth leading to Tricuspid atresia
Describe the heart tube and its derivatives
Right atrium
- usually receives IVC, SVC and coronary sinus
- broad atrial appendage
Left atrium
- usually receives pulmonary veins
- long narrow atrial appendage
Possible atria congenital defects
- atrial situs inversus
- ambiguous atria
- cor triatriatum
- single atrium
Ventricles right and left designations
“right” and “left” describe morphology and not position in the body
Ventricles anterior-posterior location
The RV is anterior the LV is posterior
The RV develops from?
the part of the heart tube closest to the truncus
Variations of the ventricles
- Ventricular inversion
- Single ventricle (LV or RV morphology)
Right ventricle valves
tricuspid valve
RV gross structural organization
Tripartite
- Inlet
- Body
- Outflow (conus)
Right ventricle wall properities
- Trabeculated
- built for pulmonary (light work)
RV purpose
built for light work (pulmonary)
LV structure-function relationship
smooth walled, built for systemic work
LV valves
mitral valve
LV general structural description
- Bullet shaped
- inlet
- absent conus
Great arteries
Normally related great arteries
- pulmonary artery off RV
- Aorta off LV
Transposition of the great arteries
Pulmonary artery off the LV
Aorta off the RV
Atretic arteries
During fetal life, either great artery can be atretic
The patent ductus arteriosus then supplies blood to both circulation
Describe the transposition of the great arteries
Conus or infundibulum
- pulmonary artery - anterior and superior
- Subaortic conus regresses
- aortic valve posterior and inferior
- abnormal regression of the conus causes many congenital heart defects
If the conus regresses under both arteries it would by?
Double outlet left ventricle
If the conus regresses under both great arteries, they will arise posteriorly and inferiorly i.e. over the left ventricle
Types of atrial situs
- situs solitus
- situs inversus
- situs ambiguous
Ventricle defects
- D-looped
- L-looped (inverted)
Great artery defects
- normally related
- inverted
- transposition - D or L
- aorta to right or left of PA
- Malposition
- partial resportion of the conus
Resistance =
pressure
flow (Q)
Vasofilation effect on resistance
lower resistance and increase flow
vasoconstriction effect on resistance
- increase resistance
- decrease flow
Pulmonary vasodilation is in response to?
oxygen
Pulmonary vasoconstriction is in response to?
hypoxia
What receptor is responsible for systemic vasoconstriction
alpha agonists
Pulmonary hypertension
abnormal musculature around smaller pulmonary arterioles
abnormal vascular resistance at birth
- Hypoplastic lungs
- Abnormal musculature
- unable to vasodilate
What is the Ao sat compared to the LA sat in a normal heart
Ao sat = LA sat
Pulmonary vasodilation is in response to?
oxygen
Pulmonary hypertension
abnormal musculature around smaller pulmonary arterioles
Lack of regression or secondary remodeling in response to high blood flow to lungs
(eg VSD, ASD, other) and/or hypoxia
Normal heart pressures in systole
pressures are equal when chambers are connected ventricle and aorta
Normal heart pressures in diastole
atrium and ventricle pressures are equal when chambers connected
Qp/Qs =
Ao Sat - MV sat
PV sat - PA sat
Qp/Qs >1.5
- volume overload
- risk for irreversible pulmonary vascular changes if not repaired
Clinical consequences of ASD
volume overload of right heart - well tolerated for 20+ years
- atrial arrhythmia
- exercise intolerance
- congestive heart failure
- pulmonary hypertension - Eisenmenger syndrome
- Shorten lifespan; repair early to avoid above
Clinical consequences of ASD physical exam findings
- right ventricular lift or heave
- wide splitting of S2 (late P2 closure)
- +/- pulmonary flow murmur (can sound innocent)
- murmurs can be heard when blood crosses an obstruction at high velocity or when a higher volume of blood crosses a normal structure (pulmonary valve annulus)
Septal ductus arteriosus
Ventricular septal defect locations
- multiple locations
- variable spontaneous closure, relationship to valves
Ventricular septal defect flow depends on
- size of the hole
- relative systemic and pulmonary vascular resistance in systole
Qp:Qs ratio in?
Ventricular septal defect
or
atrial septad defect
Ventricular septal defect symptoms depend on?
depend on flow to lungs
What are the Ventricular septal defect symptoms
- tachypnea
- tachycardia
- poor growth
High pulmonary resistance in ventricular septal defect
high pulmonary resistance = less flow = less symptoms
Physical exam findings in ventricular septal defect
lateral displacement of apical impulse
harsh, high frequency murmur or loud P2; narrowly split S2
ventricular septal defect indications for surgery
- poor growth
- persistent pulmonary hypertension
- aortic valve prolapse into defect
- most repaired in 1st 6-12 months of life with surgery
- device closure available but conduction system issues
Aortic stenosis effects
left ventricular hypertrophy
Aortic stenosis gradient depends on
- size of annulus
- mobility of leaflets
- cardiac contractility
Clinical consequences of Aortic stenosis: symptoms
symptoms depend on how quickly the load develops
- Exercise intolerance
- risk of sudden death
- left ventricular dysfunction (gradient decreases)
Aortic stenosis physical exam findings
early systolic ejection click
systolic murmur, RUSB and radiating into the neck
Tx options for aortic stenosis
Coarctation of the aorta features
Tetralogy of fallot: Shunt depends on?
resistance
Tx of tetralogy of Fallot
Single ventricle lesions
- Staged palliation
- 1st - assure appropriate systemic and pulmonary blood flow
- 2nd start to separate blue and red blood (lower volume load on a single ventricle)
- 3rd separate blue and red blood
Single ventricle lesions prognosis
Question
Atrial shunting with PS
2 questions
Summary
