Apex- neonates: congenital heart disease Flashcards
In the fetus, where does gas exchange occur?
At the placenta
*organ of respiration
What are the 3 fetal shunts and where do they shunt blood and what do they bypass?
- Ductus Venous → shunts blood from the umbilical Vein to the iVc, bypassing the liVer
IVC → RA
- Foramen ovale → shunts o2 rich blood (from DV) from the RA to the LA, bypassing the lungs
- Ductus Arteriosis → shunts o2poor blood (from lower body, ivc, ra, rv) from the pulmonary Artery → Aorta , bypassing the lungs
(so i guess normally during systole, blood gets ejected from RV → PA → lungs → PVs → LA
fetus will go from RV → PA → PDA → Aorta)
-oxygenated blood from the ductus venouses and deoxygenated blood from the lower body coverge in the IVC where there is then 2 streams of blood traveling at different rates
> higher veloicy, oxygenated blood from the ductus venosus, flows across the flap of tissue (eustachian valve)- which preferentially diverts the oxygenated blood across the foramen ovale (RA > LA) to go and perfuse the myocardium and developing brain
> lower velocity (deoxygenated blood) is preferentially directed to the RV and pulmonary artery → ductus arteriosus → proximal descending aorta (immediately distal to the left subclavian artery) and perfuses the lower body and some of it returns to the placenta via its two umbilical arteries
What structure preferentially diverts oxygenated blood across the foramen ovale
Eustachian valve
What happens physiologically when baby takes first breath?
lungs expand, PaO2 increases, PaCo2 decreases
*lowers pulmonary vascular resistance
What happens when the umbilical cord is clamped?
theres an increase in SVR
-the decrease in PVR from first breaths + increase in SVR from cord clamp results in LA pressure climbing higher than RA pressure and then
- the flap of the foramen ovale closes and
- blood flow starts reversing from aorta (high pressue) back thru ductus arterosus and when that is exposed to increased O2 it closes
discuss prostaglandins and the ductus arterosis
prostaglandins released from the placenta help maintain a PDA
-when cord is clamped, there is decreased circulating levels of PGE1 which results in DA closure (+ exposure to oxygenated blood from backflow thru a newly pressurized aorta)
how would you know if a baby still has a PDA
they will have a continuous systolic and diastolic murmur
Functional vs anatomic closure of the Foamen ovale
adult remnant?
How many adults have a PFO? Problem?
Functional- cord clamping (LAP > RAP → increased SVR)
Anatomic closure = 3 days
fossa ovalis
30% ; increased risk of paradoxical embolism (embolism travels to brain instead of lungs)
Fuctional vs anatomic closure of the ductus arteriosus
adult remnant
functional - when SVR > PVR (increased PaO2 and decreased prostagladins from placenta)
anatomic closure = several weeks via fibrosus
ligamentum arteriosum
What can close vs open a PDA?
so think… prostaglandins from the placenta keep it open…. so it can be opened with:
→ Prostaglandin E1 (PGE1)
think NSAIDS block the syntehsis of praostaglandins by inhibiting COX 1 and COX 2 (the patheways where arachadonic acid gets converted to prostagladins and thromboxanes)
is so you can give **indomethacin (a porstaglandin synthase inhibitor) **
When does the ductus venous close?
adult remnant
when the umbilicar cord is clamped
(shunts blood flow from the umbilical cord to IVC, no blood from umbilical cord = no need for it)
ligamentum venosum
T/F- the ligamentum venosum cannot reopen
True
T/F- all the anatomic shunts essentially close functionally with umbilical cord clamping
True
FO bc the increase in SVR results in increased LAP > RAP
DA bc SVR > PVR = increased PaO2 and decreased prostaglandin release from placenta
DV bc no blood flow is coming from placenta now
When does the FO vs DA close anatomically?
FO - 3 days
DA - 3 weeks (“several” - just tryna keep it easy)
DV closes with cord clamping
the 4 big conditions that increase PVR
Hypercarbia
Hypoxemia
Hypothermia
Acidosis
What 3 things are the size and direction of a shunt depdendent on?
- ratio of PVR to SVR
- R → L shunt occurs when PVR is higher than SVR
- L → R shunt occurs wehn SVR is greater than PVR (isnt it always?) - Pressure gradients between the cardiac chambers or arteries involved
- Compliances of the cardiac chambers
Calculation for PVR
normal
Calculation for SVR
normal value
increased or decreased SVR:
decreased SNS tone
decreased SVR
how does hemodilution affect PVR and SVR
decreases them both
no idea why - less viscosity? idk
Right to Left Cardiac Shunts
-Mneumonic x 2
“To the left, to the left, move your FEETTT”
Fallot (TOF)
Ebsteins anomaly (tricuspid valve abnormality)
Eisenmenger syndrome
Transposition of the great arteries
Truncus arteriosus
Total anaomalous pulmonary venous connection
5 T’s
1. TOF
2. Tricuspid valve abnormality (Ebstein)
3. Transposition of the great arteries
4. Truncus arteriosus
5. Total anamalous pulmonary venous connection
Left to Right shunts
Mneumonic
people of the VA are not “PC”
VSD
ASD
PDA
Coarctation of the Aorta
Hemodynamic goals of someone with a right to left shunt
Maintain SVR
Decrease PVR
→ hyperoxygenate
→hyperventilate
→avoid lung hyperinflation
-goals with shunts are always SVR and PVR related
How is inhalational induction affected with somone with a right to LEFT shunt? why?
decreased
- less blood going to lungs to pick up volatile agent
- shunted blood dilutes whatever blood is getting to the lungs and picking up the agent → gets diluted by the shunted blood
Is inhalational induction with a right to LEFT shunt most profoundly different with less soluable or more soluable agents
more profound with less soluable agents (N20 and desflurane)
-less difference noted with more soluble agents (isoflurane)
just remember, iso already takes forever , so if it takes a little longer- no one will notice; but someone will def notice nitrous and des taking longer
Faster or slower IV induction with right to LEFT shunt
what about a left to right shunt?
faster
-iv med bypasses lungs and directly enters systemic circulation → VRG
possibly prolonged as blood re-enters pulmonary circulation
how will a VSD affect your inhaltional induction
VSD = left to RIGHT shunt
-blood still gets to lungs
negligible effect
How do you want to manage your vent settings with someone with a VSD
low FiO2
don’t hyperventilate → keep CO2 normal
want to avoid decreases in PVR which would promote increased blood flow (o2 and hypocarbia dilate the vasculature)
so VSD = low systemic blood flow and high pulmonary blood flow
avoid decreasing PVR (which would encourage more pulmonary blood flow)
& avoid increasing SVR (which would make it harder for pulm blood flow to get out and make it back up and increase even further) + higher pressures in the left heart force blood to the right across the septal defect
Tetralogy of Fallot is characterized by what 4 defects?
4 goals
- RV outflow tract obstruction → pulmonary stenosis
- RV hypertrophy due to above
- VSD bc the septum get malaligned from the hypertrophy
- Overriding aorta that receives blood from both ventricles? - i guess RV > LV > aorta? idk
VAPoR
VSD
Aorta that overrides the RV and LV
Pulmonary Stenosis (obstruction to RV ejection)
RV hypertrophy
increase SVR
decrease PVR
maintain contractility and HR
increase preload
What’s the most common cyanotic congenital heart anomaly?
TOF
Why are TOF kids at increased risk for thromboembolism and stroke?
bc the blood thats shunted thru the VSD and into systemic circulation is not oxygenated
-body senses this decrease in oxygenated blood in the systemic circulation and compensates with erythropoiesis - makes more blood cells to help carry o2; however this increase in RBCs increases the risk of thromboembolism and stroke
What does a TET spell result in? (2)
hypoxemia and cyanosis
What is a tet-spell precipitated by and what happens?
increased SNS activity (crying, agitation, pain, defication, fright, trauma)
-this increased SNS activity** increases myocardial contractility**, worsening the RVOT obstruction
-blood flows across path of least resistance, so increased resistance at the RVOT will force blood through the VSD → increased right to left shunting → hypoxemia
T/F- only kids with unrepaired TOF can experience tet spells
True
What 2 things will kids automatically do when having a TET spell?
hyperventilate and squat
- they hyperventilate with the onset of hypoxemia to try and get more o2 to body
- they squat → increases IAP → compresses abdominal arteries → increases RV preload, SVR, and blood flow through the RVOT
3 things to do/increase for a TET spell
position to place infant in
3 things to avoid/decrease
- administer 100% fio2 - tx hypoxemia
- Give IVF - full ventricle will reduce RVOT obstruction
- increase SVR - neo → increasing SVR so blood has a harder time just sneaking across the VSD and more willbe directed towards the RVOT
knee to chest postion- to mimic squatting
- Avoid inotropes - the already hypertrophied RV will worsen RVOT obstruction if contracting harder
- Avoid excessive airway pressure → compresses pulm vessels and increases PVR
- Reduce SNS stimulation → deepen anesthesia, short-acting beta blocker - slow HR = more time for RV to fill + SNS stimulation increases PVR which will make it harder to get blood into lungs
Anesthetic hemodynamic goals : TOF
SVR
PVR
HR
Contractility
Preload
SVR- increase
PVR - decrease
HR and CX - maintain (avoid increases)
Preload- increase
What lab value would you want to look at if your kid has TOF and why
RBCs
-polycythemia will be proportional to the degree of chornic hypoxemia
-more rbcs = worse
Induction agent for TOF and why
what opioid to avoid and why
Ketamine 1-2mg IV or 3-4mg IM
-increases SVR, reducing shunting
morphine (or any histamine releasing drugs) - decreases SVR, increas. sh
TOF will result in what kind of axis devation on EKG?
what will the heart look like on CXR
right axis ( - I, + AVF)
due to RV hypertrophy
boot shaped
Failure of the fossa ovalis to close results in what type of atrial septal defect?
A. Primum
B. Secundum
C. Sinus Venosus
D. Perimembranous
B. Secundum (occurs in the middle 1/3 of the atrial septum - represents 80% of all ASDs)
Primum ASDs occur in the lower region of the atrial septum, just above the tricuspid valve
Sinus venosus ASDs are located just below the IVC or less commonly just above the IVC
What is the most common type of ventricular septal defect?
perimembraneous.
located in the middle of the ventricular septum, just below the septal leaflet of hte tircuspid valve
is blood flow thru an ASD (ie PFO) usually cyanotic (right to left) or acyaonotic (left to right)
what about VSD?
PFO- usually acyantoic (left to right) (high pressure to low pressure)
same
What is the most common congenital cardiac anomaly in kids?
what about adults?
VSD
* asignificant number of VSDs close by the kid is 2
bicuspid aortic valve = most common congenital cardiac defect in adults
Hemodynamic mangement of ASD with anesthesia
hemodynamic effects of anesthetic agents are usually well tolerated
How do they fix ASDs?
usually with a percutaneous transcatheter device
can also be done open with a suture or patch
Which Trisomys are associated with VSDs
21
18
13
- think cool years-
21 drink
18 adult
13 teen
if you hear your patient has a VSD, what do you want to know about it?
small or large
-if VSD is small- pulm blood flow is only slighlty increased and they tolerate anesthesia well
-if VSD large - RV and LV pressures equalize and then PVR and SVR will determine the direction of blood flow
Goals with VSD
avoid decreases in PVR and increases in SVR
- will increase shunt flow
i guess if you decrease pressure on the right and/or increase pressure on the left, its going to send more blood back to the RV and less out the aorta? - AKA: increase shunt flow
How are VSDs typically closed?
open repair with a patch
inotropic support may be needed afterwards
Do patients with VSD tolerate anesthesia well?
usually the PPV that increases PVR + volatile agents that decrease SVR lead to stable hemodynamics as long as the balance doesnt favor right to left shunting
Pt is undergoing surgical repair for coarctation of hte aorta. What is the BEST site to monitor the arterial blood pressure?
right arm
- coarctation occurs when the aorta is narrowed in the area of hte ductus arteriosus
- -LV much generate a higher pressure to overcome the increased aortic resistance and severe narrowing can limit hte amount of blood delivered to the lower half of the body
- rarily, but possibly, the coarctation could be proximal to the left subclavian artery, reducing perfusion to the left upper extremity; so thats why the right would be best
What is coarctation of the aorta?
what will be seen as symptoms?
its where the aorta narrows, usually around the level of the ductus arterosus
→obstruction of blood flow increases LV afterload
increased BP in upper extremities
decreased SBP in lower extremities +
pink upper body, blue/cyanotic lower body
why would a kid be on Prostaglandin E1?
to keep the ductus arterosis open
-coarctation of the aorta can result in decreased blood flow to the lower extremities
-keeping the PDA open helps maintain blood flow to lower extremities until surgery can be done
pulm artery to aorta
T/F- mild to moderate coarctation usually goes unnoticed for years
True
pts often develop collateral flow
Pt scheduled for a Fontan procedure MOST likely has a diagnosis of:
A. truncus arteriosus
B. ebstein’s anomaly
C. transposition of the great arteries
D. hypoplastic left heart syndrome
D. Hypoplastic left heart syndrome
most common single ventricle lesion
-all patients with a single ventricle require surgical correction with the Fontan procedure
What is characterized by a downward displacement of the tricuspid valve, right atrial dilation, and “atrialization” of the right ventricle
Ebstein’s anomaly
*there is usually an ASD or PFO
What is transposition of the great arteries?
it’s when each great vessel arises from the wrong ventricle
→ RV gives rise to the aorta (poorly- oxygenated circuit)
→ LV gives rise to hte pulmonary artery (well oxygenated circuit)
Medical emergency!!!
T/F transposition of hte great arteries is a medical emergency
True!
-cant send poorly oxygenated blood to a poorly oxygenated body and well oxygenated blood to the lungs.. dont do any good
T/F= patients with hypoplastic left heart syndrome - we should aim to increase their PVR
false- this patient has a single ventricle that pumps blood into systemic circulation. Pulmonary blood flow is passive and anything that increases PVR should be avoided
What is truncus arteriosus characterized by
a single artery that gives rise to the pulmonary, systemic, and coronary circulations.
there is usually a VSD
What is this?
Ebsteins anomaly
-downward (apical) displacement of the tricuspid valve (atrialzation) causing right atrial enlargement, usually accompanied by an ASD or PFO
What is hte most common congenital defect of the tricuspid valve?
Ebstein’s anomaly
How will the onset of IV induction agents change in someone with Ebstein’s anomaly
-downward displacement of tricuspid valve allows RV to become apart of RA (atrialization)
→ increased RAP
→ IV induction may be prolonged due to pulling of drugs in the enlarged RA
what is someone with ebstein’s anomaly at risk for?
what is the common dysrhythmia?
what is common in the postop period?
CHF *need to maintain RV function
SVT
RV vailure postop
T/F- transposition of the great arteries is compatible with intrauterine life
True bc the flow thru the ductus arteriosus and foramen ovale allow communication between both ciruclations
*Medical emergency bc no chance of survival once born
What is Rashkind procedure for?
what would be definitive surgical correction
transposition of the great arteries → creates an interarterial pathway to allow some oxygenated blood to reach the systemic circulation
intraatrial baffle and arterial switch
in what condition is blood flow into the lungs completely dependent on negative intrathoracic pressure during spontaneous breathing and should make effort effort to maintain?
hypoplastic left heart syndrome
*increased PVR is detrimental to pulmonary blood flow
this patient has a single ventricle that pumps blood into systemic circulation. pulmonary blood flow occurs passively from the SVC/IVC > pulmonary artery
T/F - pts with hypoplastic left heart syndrome are preload depdendent
True - dont let them get dry!
What anamoly results in oxygenated and deoxygenated blood being pumped into both pulmonary and systemic ciruclations thats usually accompanied by a VSD?
Truncus arteriosus
single artery gives rise to pulmonary, systemic, and coronary circulations with no specific pathway for it to go to the lungs first
why would you want to avoid decreasing PVR in a patient with truncus arteriosus
bc it will increase pulmonary blood flow and steal blood from systemic and coronary ciculations
single artery gives rise to pulmonary, systemic, and coronary circulations with no specific pathway for it to go to the lungs first
Label
- Ebstein
- Transposition of the great arteries
- Hypoplastic left heart syndrome
- Truncus arteriosis
Identify the featrues of TOF: (Select 2):
-Atrialization of the right atrium
-RVOT obstruction
-VSD
-Ductal-dependent circulation
what are the other 2
RVOT obstruction and VSD
+ RVH + Overriding aorta
atrialization is ebstein (usually ASD/PFO_
Ductal dependent circulation is hypoplastic left heart syndrome
