Right to Left Shunts Flashcards
right to left shunts often cause
cyanosis– right heart blood is shunting to the left before getting oxygenated at the lungs.
cyanosis is blue coloration of the mucous membranes, nail beds or skin whcih results from the prsence of
deoxygenated hemoglobin. the appearance of cyanosis depends on the total amount of reduced hemoglobin rather than the ratio of reduced to oxygenated hemoglobin
central vs peripheral cyanosis
central = “true” cyanosis ,central mucous membranes ae blue
peripheral= acrocyanosis, perioral cyanosis. often normal in otherwise healthy childrne .
physiology of cyanosis: when the curve shifts __, cyanosis wil occur
LEFT SHIFT– when there is an increased affinity for O2 of the Hb, and thte Hb will not release it to the tissues.
cyanosis vs hypoxemia
cyanosis is a physical sign which is usually a marker for hypoexmia.
hypoexmia is abnormally decreased arterial blood oxyten. Measured by quantity.
T/f new onset central cyanosis is an emergency
true. Cyanotic heart disease is a life-long problem, even AFTER it is repaired
Cyanotic heart disease is a ___ to ___ shunting disorder qhich cuases desautrated blood into systemic arterial system. there is a mixing of deoxy blood with oxy blood.
what are cyanotic heart diseases that causes increased (or normal if small) pulmonary flow?
right to left shunting disorder
- truncus areriosis
- transposition of the great arteries
- total anomalous pulmonary venous return
what are cyanotic heart diseases that causes decreased pulmonary flow?
tetralogy of fallot
tricupsid atresia ( can also be normal or increased)
crticial pulmonary stenosis/pulmonary atresia
Fetal circulation:
Blood returns to the body by the __ venous system from the placenta and mixes with systemic venous blood
Blood is preferentially distributed through the __ __ into the __ ___ by means of the __ __ in the liver
__ and __ blood is aimed through the __ __ and __
A small proportion goes to the pulmonary trunk, but the majority is directed through the __ _ into the aorta
Blood returns to the body by the umbilical venous system from the placenta and mixes with systemic venous blood
Blood is preferentially distributed through the foramen ovale into the left atrium by means of the ductus venosus in the liver
IVC and SVC blood is aimed through the tricuspid valve and RV
A small proportion goes to the pulmonary trunk, but the majority is directed through the ductus arteriosus into the aorta
post natal circulation:
during Delivery:
Fluid in the fetal airways is removed with
compression and spontaneous breathing
- Umbilical cord is clamped (__ Systemic Vascular Resistance)
Breathing: - increases __ blood flow
- increased __ to the left atrium
- closure of the __ ovale flap
- increased __ from the LV
higher oxygenation and other changes in blood like __, __, etc. causes the pulmonary resistance to __
__ __ changes direction and now is from __ to __ artery
Functional closure of the PDA begins in 12-15hrs*
Permanent closure is within 1 wk, sometimes takes up to 3 weeks*
Pulmonary vascular resistance falls completely by 4-6 weeks postnatally
post natal circulation:
during Delivery:
Fluid in the fetal airways is removed with
compression and spontaneous breathing
- Umbilical cord is clamped (increases Systemic Vascular Resistance)
Breathing: - increases pulmonary blood flow
- increased return to the left atrium
- closure of the foramen ovale flap
- increased output from the LV
higher oxygenation and other changes in blood like Prostaglandins, NO, etc. causes the pulmonary resistance to fall
Ductus arteriosus changes direction and now is from aorta to pulmonary artery
Functional closure of the PDA begins in 12-15hrs*
Permanent closure is within 1 wk, sometimes takes up to 3 weeks*
Pulmonary vascular resistance falls completely by 4-6 weeks postnatally
cilnical evaluation of cyanosis $
general principles of management of cyanosis
_____ (chemical) maintains patency of the ductus arteriosus.
prostaglandin E1
in cyanosis due to cardiac pathology, PaO2 is ___, and there is little or no changelittl with oxygen
O2 is LOW
hyperoxtic test:
placing 100% FiO2 and use right arm ABG for PaO2.
if baby is less than 90% on oxygen, its likely to be R-L cyanotic heart shunt disease
note: room air oxygen saturation should be monitored in a cyanotic baby
Main cyanotic CHD that is due to independent pulmonary and systemic circulations
transposition of the great arteries
Main cyanotic CHD that is due to obstructed pulmonary blood flow
tetalogy of fallot
- tricupsid atresia
- pulmonary atrsia
- ebsteins anomaly
Transposition of the great arteries Cyanotic CHD is due to independent pulmonary and systemic circulations.
- in TGA, the aorta arises from ___ and the pulmonary artery arises from __ in a parallel circulation fashion.
- in TGA, the aorta arises from RV and the pulmonary artery arises from LV in a parallel circulation fashion.
Blood on the right side therefore never gets oxygenated and is always systemic, and blood on the left side never gets deoxygenated.
presentation of TGA
cyanoasis
NO MURMUR PRESENT
no respiratory distress
CXR looks like an egg on a string
TGA is due to complete indepedndence of the pulmonary and systemic circulations. What is the management and how can mixing be rimproved?
rely on on the existing atrial septal defect
- keep the ductus open– use prostaglandin
- create an artifical ASD- balloon atrial septostomy
- you gotta do an arterial switch operation so that the pulmonary veins are attached to left atria and the pulmonary arteries are attached to left ventricle. Prior, the aorta connected to the RV which is not correct.
no improvement with O2 = cyanotic CHD issue
- no murmur, cyanotic, no respiratory distress, well perfusion all point to presentation of transposition of the great arteries CHD
4 parts to tetralogy of Fallot
- pulmonary stenosis
- over-riding aorta
- VSD
- RVH
- severe RV outflow obstruction due to pulmonary stenosis causes decreased pulmonary blood flow. the VSD R–>L shunt causes cyanosis.
- if severely stenotic, it presents in the first hours when the PDA closes
Pink vs blue TOF
characteristic finding of tetrology of fallot on xray
the boot shape CXR indicates a blue TOF
Management of TOF
timing of surgeyr depends on the amount of pulmonary stenosis.
- blue tof often requires earlier surgery
- well at birth, now cyanotic indicates that PDA is probably closing off now.
systolic ejection murmur with singlly loud S2 indicates that something is obstructing flow from one of the ventricles.
could be tetralogy of fallot
an ____ is nearly complete mixing of venous and arterial blood in a common chamber or artery.
admixture
- forexample ; common arterial trunk mixing is truncus arteriosus.
common mixing in a ventricle is total anomalous pulmonary venous return
presentation of truncus arteriosus : Single overriding vessel Mixing of deoxygenated /oxygenated blood
- mild cyanosis (not as bad as TGA when literally everything is so separated half the blood wont even be oxygenated
- normal S1, single S2– there is no P2/A2 separation…the tubes to pulmonary or systemic circulation are converging.
- ejection click
- systolic EM
- tachypnea, hepatomegaly.
- CXR can be normal or with increased pulmonary vascular markings
management of truncus arteriosus
condition where tricuspid valve fails to develop normally
tricuspid atresia
- hypoplastic RV
- VSD
What hapens in total anomalous pulmonary venous drainage?
this occurs when pulmonary veins return back to the right side of the heart
Symptoms are dependent on if the veins are obstructed– only mild cyanosis if unobstructed
outline the hemodynamics of total anomalous pulmonary venous drainage
- pulmonary veins return right back to the right side of th eheart.
- blood from puolmnary veins drain into SVC
- the LA receives blood thoruh a R–>L shunt from Ra to LA.
causes a systolic ejection murmur LUSB
- normal S1, split S2.
- as PVR falls, increased RR/tachypnea and increased WOB.
