congenital heart disease Flashcards
purpose of umbilical vein and how many
carries oxygenated blood from mother to fetus
1 umbilical vein
purpose of umbilical artery and how many
carries deoxygenated blood from fetus to mother
2 umbilical arteries
purpose of ductus venosus
shunts blood from umbilical vein to IVC (bypasses liver)
purpose of foramen ovale
shunts blood from RA to LA (bypasses lungs)
purpose of ductus arteriosus
shunts blood from pulmonary artery/trunk to aorta (bypasses lungs)
how ductus arteriosus closure is facilitated
decreased PVR reverses flow form ductus arteriosus, which exposes DA to increased PO2, and closes DA.
decreased circulating PGE1 (usually released from placenta) also facilitates DA closure
functionally closes with SVR > PVR
murmur that you’d hear if ductus arteriosus remained open
systolic and diastolic murmur
how foramen ovale closure is facilitated
first breath expands lungs and deceases PVR,
placenta separates from cord wall and increases SVR,
this creates LA pressure > RA pressure and PFO closes
drugs that can close and open PDA
closure can be facilitated with indomethacin, a prostaglandin synthase inhibitor
it can be opened with PGE1
how long does it take PFO to close
3 days
how long does it take PDA to close
several weeks via fibrosis
cardiac circulation in fetus versus adults
adults: circulation in parallel
fetus: circulation in series
right to left shunt occurs when
PVR is > SVR
(blood bypasses the lungs. “blue baby”)
left to right shunt occurs when
SVR > PVR
(oxygenated blood recirculates through right heart and lungs. “pink baby”)
PVR equation and normal PVR
=(mPAP - PAOP)/CO * 80
normal: 150-200dynes/sec/cm^5
SVR equation and normal SVR
=(MAP - CVP) /CO * 80
normal: 800-1500 dynes/sec/cm^5
factors that increase and decrease PVR
factors that increase and decrease SVR
examples of right to left shunts
“five T’s”
TOF
Transposition of great arteries
tricuspid valve abnormality (Ebsteins anomaly)
Truncus arteriosus
Total anomalous pulmonary venous connection
hemodynamic goals for patients with right to left shunts
maintain SVR and decrease PVR
maintain contractility and HR
effect of right to left shunt on inhalation induction
volatile does not pass through lungs to rate of FA/FI is slowed and so is rate of induction
difference is more profound with less soluble agents (N2O and desflurane) and less profound with more soluble agents (iso)
effect of right to left shunt on IV induction
faster
pathophysiology of left to right shunt includes
decreased systemic BF which decreases CO and creates HoTN (bc blood is only recirculating through right heart and lungs, not out into the body)
increased pulmonary BF which creates pHTN and RV hypertrophy
hemodynamic goals for a patient with a left to right shunt
avoid increased SVR
avoid decreased PVR by avoiding alkalosis, hypocapnia, high FiO2 and vasodilators
examples of left to right cardiac shunts include
VSD
ASD
PDA
coarctation of aorta
effect of L to R shunt on inhalation induction
negligible
effect of L to R shunt on IV induction
possibly prolonged
Eisenmenger Syndrome
when a patient with L to R shunt develops pulmonary HTN. increased right heart pressures cause a flow reversal through cardiac defect, likely leading to right to left shunt, hypoxemia, and cyanosis
TOF is characterized by these 4 defects
VSD
aorta that overrides RV and LV (and receives blood from both ventricles)
pulmonic stenosis (obstruction to RV ejection)
RV hypertrophy
RVOT obstruction/compensation and TOF
increased RVOT obstruction shunts more deoxygenated blood to VSD and out of the aorta
body compensates with erythropoiesis but that leads to polycythemia and increased risk of thromboembolism
pathophysiology of a TET spell
precipitated by increased SNS activity which increases myocardial contractility and increases resistance at RVOT.
this shunts more deoxygenated blood to VSD which causes right to left shunt and hypoxemia
essentially a R->L shunt r/t increased PVR
how the child will compensate for a TET spell
hyperventilate to compensate for hypoxemia
squat to increase intra abdominal pressure, which increases RV preload and SVR, and restores BF to pulmonary arteries which reverses ish the magnitude of right to left shunt
perioperative treatment of a child in a TET spell
FiO2 100%
administer fluids to expand intra vascular volume
increase SVR with neo to augment SVR to PVR ratio
reduce SNS stimulation (deepen anesthesia, beta blockade with esmolol)
avoid inotropes (can worsen RVOT)
avoid excessive aw pressure
place infant in knee chest position to mimic squatting
best induction agent for TOF baby
ketamine 1-2mg/kg IV or 3-4mg/kg IM
increases SVR and reduces shunting
histamine releasing drugs and TOF baby
avoid them since it decreases SVR. this includes morphine, meperidine, atracurium
most common congenital cardiac anomaly in children
VSD
early signs of ASD
poor exercise tolerance, later could include atrial flutter, afib, CHF
isolated ASD and abx
not indicated unless within 6mo of ASD repair
what conditions is VSD usually associated with
trisomy 13, 18, 21
VACTERL (vertebral, vascular, anal, cardiac, tracheoesophageal fistula, renal, limb abnormalities)
CHARGE (coloboma, heart anomaly, choanal atresia, retardation, genital and ear abnormalities)
how are VSD’s closed
usually close on their own by age 2 but if you need surgical intervention, they are an open approach via a patch (versus ASD is usually closed)
isolated VSD and abx
not indicated for isolated VSD but is within 6 months of surgical repair
pathophysiologic anatomy of coarctation of aorta
when aorta narrows in area of ductus arteriosus. LV must then generate higher pressure to overcome increased aortic resistance. Severe narrowing can limit blood delivered to lower half of body. Pink upper half, cyanotic lower half.
SBP and coarctation of aorta
if it is proximal to left SCA take off, SBP in RUE will be > LUE
SBP is reduced in LE’s
what does LE perfusion rely on with coarctation of aorta severe obstruction
relies on PDA
management of BF to LE’s with patient that has coarctation of aorta
reduced BF facilitates organ and limb ischemia.
PGE1 is administered to facilitate DA potency until surgery can be performed (anastomosis)
Ebsteins anomaly
downward (apical) displacement of tricuspid valve. Part of RV becomes part of RA which causes right atrial enlargement. This causes an ASD or PFO.
pathophysiologic anatomy of transposition of great arteries
each vessel arises from wrong ventricle.
RV gives rise to aorta
LV gives rise to p. artery
RV circuit: systemic venous blood: RV–>aorta–>repeat
doesn’t go through pulmonary circulation
LV circuit: LV–>lungs–>repeat
doesn’t go through systemic circulation
treatment for patient with transposition of great arteries
keep PDA open with PGE infusion (temporary fix)
Rashkind procedure allows some oxygenated blood to get to systemic circulation
intraartial baffle and arterial switch procedures are definitive tx
anatomic features of hypo plastic left heart syndrome include
hypoplastic LV and aortic arch
mitral and aortic stenosis or atresia
ductal dependent circulation
Goal of HLHS surgical correction: Norwood stage 1
when: neonatal period
goal: aortic reconstruction. aortic arch now rises from pulmonary trunk. p. arteries are disconnected from p. trunk and are used to create a shunt from SCA to RV
Goal of HLHS surgical correction: Norwood stage 2
when: 3-6mo
goal: shunt from first procedure is taken down and new connection is made between SVR and p.arteries
Goal of HLHS surgical correction: Norwood stage 3
when: 2-4 years (fontan procedure)
goal: conversion to fontan circulation: IVC is connected to p.artery with a conduit
management of a patient after a fontan procedure
patient has a single ventricle that pumps blood into systemic circulation. pBF occurs passively from SVC/IVC to p.artery
BF to lungs is completely dependent on intrathoracic pressure. therefore pp ventilation is bad news bears. spontaneous ventilation is preferred.
preload dependent- give fluids
pathophysiologic anatomy of truncus arteriosus
single artery that gives rise to pulmonary, systemic, and coronary circulations. mixed blood is pumped continuously. usually a VSD as well.
increasing PVR or p.BF can steal from systemic and coronary BF
truncus arteriosus surgical intervention
can restore 2 ventricle arrangement by separating pulmonary from systemic BF by closing VSD
which congenital heart defects are associated with ventricular outflow tract obstruction?
TOF
ebsteins anomaly
p. stenosis with ASD or VSD
eisenmengers syndrome
