Cardiology Flashcards
Where is the obstruction in the vast majority of aortic coarctation cases?
Distal to L subclavian artery, often at location of ductus arteriosus (aortic isthmus)
Is aortic coarctation more common in boys or girls? Syndromic caveat?
Boys
But seen in Turner syndrome
What lab finding might be apparent in aortic coarctation and why?
Raised lactate as hypoperfuse lower limbs
How does aortic coarctation present on exam?
Disparity in pulse volume in arms vs legs, also BP differences
Absent femorals
Systolic murmur below left clavicle is typical but variable
When might a coarctation present and why? What implications does this have for management?
Day 2 plus of life after a PDA has closed - it is duct dependent
Can give prostins to keep duct open and prevent CV collapse
What is milrinone and what is it used for?
Phosphodiesterase 3 inhibitor which increases heart contractility and reduces pulmonary vascular resistance, also decreases afterload via peripheral vasodilation
Used in heart failure and LCOS as well as post cardiac surgery to maintain ventricular function
How are PDAs managed?
Medical - IV indomethacin, ibuprofen in first 14 days of life
Surgical - cardiac catheter closure or ligation via open thoracotomy
What is ALCAPA?
Anomalous Left Coronary Artery from Pulmonary Artery
L heart therefore gets oxygen poor blood and undergoes ischaemia. Low BP in pulmonary artery can also cause reversal of flow over time so blood flows from LCA into pulmonary artery - pulmonary steal and worsening ischaemia
How many vessels are in the umbilical cord?
3 - 2 UAs and 1 UV
Where do the umbilical arteries branch off from?
Internal iliacs
What does the ductus venosus do?
Shunts blood across the Fetal liver to the IVC
What shunts blood across the nonfunctional Fetal liver? Into what?
Ductus venosus to the ivc
How does blood flow through the Fetal heart and why?
From R atrium into L atrium via foramen ovale
Because pulmonary vascular pressures are very high (hypoxic pulmonary vasoconstriction) which transmits back into RV, so pressure in R heart is greater than L and blood flows from R to L
What does the ductus arteriosus do?
Allows blood to flow from the pulmonary artery into the descending aorta at the isthmus, bypassing the nonfunctional Fetal lungs
What are the 2 methods the Fetal circulation uses to bypass the lungs?
Foramen ovale
Ductus arteriosus
What are the 3 shunts in the Fetal circulation?
Ductus venosus
Ductus arteriosus
Foramen ovale
What 2 major circulatory changes occur when the baby is born and what happens as a result of this?
Placenta disconnects from circulation
Lungs become functional and pulmonary pressure falls
RA and RV pressures fall; eventually to less than L sided pressures and flow reverses, closing the foramen ovale
What physiologically clamps the umbilical cord?
Wharton’s jelly
Within how long of birth does the foramen ovale usually close?
Few mins
Why does the ductus arteriosus close? What keeps it open before this?
Due to rising oxygen levels in the circulating blood
Prior to this the placenta produces prostaglandins which helps to keep it open. When this falls after birth the DA closes
3 conditions that have ductus dependent systemic circulation?
Coarctation
Critical aortic stenosis
Hypoplastic L heart syndrome
Which way does the blood flow in conditions with ductus dependent systemic circulation?
From pulmonary artery to aorta
4 conditions with ductus dependent pulmonary circulation? Which way does the blood flow?
Critical pulmonary stenosis Pulmonary atresia Tricuspid atresia Tetralogy of Fallot Blood flows from aorta to pulmonary artery
3 common L to R shunt heart defects?
VSD
PDA
ASD
2 common R to L shunt heart defects?
TOF
TOGA
What is the major presenting symptom of L to R shunts and stenotic heart disease/coarctation?
Breathlessness
What is the major presenting sign of R to L heart disease shunts?
Blueness
What is the most common mixing heart disease that causes breathlessness and blueness?
Complete AVSD
What are the components of ToF?
Overriding aorta
Which overrides a large VSD
Pulmonary infundibular stenosis (R ventricular outflow tract obstruction)
Which causes RVH
4 diseases/syndromes associated with ToF?
Down’s syndrome
Di George syndrome
Fetal alcohol/valproate/phenytoin
PKU
How does ToF present?
Cyanosed and clubbed kids
Kids may squat or present with apnoeic tet spells
When do tet spells often occur?
Whilst/after feeding
Crying
Defecating
Tachycardia or hypotension
What is the common underlying cause of ToF?
Failure of subpulmonic conus to expand
What factor influences the severity/age of presentation of ToF?
The degree of RVOTO (stenosis)
What is the underlying cause of tet spells?
Sudden decrease in SVR which increases the R to L shunting across the VSD, acutely decreasing PaO2 and increasing PaCO2
This causes acidosis and increase in breathing rate, which increases negative thoracic pressures and increase venous return to R heart, worsening the R to L shunt
Which carries on the cycle
What is responsible for the classic XR finding in ToF?
Boot shaped heart - the prominent R ventricle and decreased pulmonary vascularity
How do you manage a tet spell?
High flow O2
Calm down, reduce pain
Encourage squatting if older
Consider opioids
Why do kids with ToF squat?
To increase systemic vascular resistance and reduce the R to L shunt
Also acutely drops venous return
Broadly how do you manage ToF?
Duct dependent so give prostin to maintain patency and surgically correct within 1st year of life
Why is TOGA bad and what is required to maintain blood flow to body?
Creates 2 separate parallel circulations
So needs PDA or VSD to keep L to R shunt and maintain oxygenation
CXR sign of TOGA?
Egg on a string appearance of heart
What is persistent truncus arteriosus?
Failure of truncus to divide into pulmonary artery and aorta
Leads to mixed blood in circulations causing cyanosis at birth
What is Ebsteins anomaly?
Medial displacement of the septal and posterior leaflets of the tricuspid valve into R ventricle, creating severe tricuspid regurgitation and functional RV hypoplasia
What maternal medication is a RF for Ebsteins anomaly?
Lithium
What rhythmic disturbance is associated with Ebsteins anomaly?
WPW syndrome
What are TAPVD and PAPVD?
One or more pulmonary veins don’t return to L atrium
In TAPVD, a single pulmonary vein drains straight to the SVC leading to mixing
Needs a R to L shunt to maintain systemic circulation
What is Eisenmengers syndrome?
Seen in long term L to R shunt defects that would usually only cause breathlessness (ASD, VSD, PDA)
Over time pulmonary hypertension due to this and causes RVH, which eventually reverses the defect into a R to L shunt and causes cyanosis
What is heterotaxy/isomerism?
Improper positioning of visceral organs, including situs invertus
What is R atrial isomerism?
Asplenic syndrome - as if body was trying to be symmetrically R sided so have bilateral SVC, APVD, TOGA, no Coronary sinus, pulmonary stenosis, endocardial cushion defects e.g. AVSD
Plus no spleen, midline liver, trilobar lungs, R sided stomach with malrotation
What is L atrial isomerism?
Polysplenic syndrome - as if body was trying to make itself symmetrically L sided so get interrupted ivc, azygous continuation, pulm/aortic stenosis, AVSD
Plus multiple but non functional splenules, bilobated lungs, hepatic drainage into L atrium and gut malrotation
What is the Norwood procedure?
Treatment for Hypoplastic L heart syndrome made of 3 steps (staged palliation) as alternative to heart transplant
What are the 3 steps of the Norwood procedure?
Stage 1 where R ventricle is turned into main ventricle for body and lungs
Stage 2 - bidirectional Glenn operation (6m after stage 1) to allow half of blood to flow around lungs
Stage 3 - Fontan (18-36m post Glenn) to connect IVC to pulmonary artery
What is the surgery for Hypoplastic L heart syndrome called?
Norwood procedure with bidirectional Glenn and Fontan
What 2 heart defects is Di George particularly associated with?
TOF
Truncus arteriosus
What cardiac defect is mother with DM associated with?
Transposition of great arteries
What does a PDA murmur sound like?
Continuous syst and diast machine like murmur
What infection is associated with PDA?
Rubella
What are the characteristics of an innocent cardiac murmur?
Very positional
Musical quality
Worsens with e.g. Infection or tachycardia
What is the most common type of ASD? Other types?
Secundum most common
Also primum, sinus venosus and PFO
What heart defect is associated with trisomy 21?
Endocardial cushion defect - AVSD plus common valve in middle
What is a tet spell an indication for?
Surgery ASAP
When is surgery for TOF usually done?
Wait til at least 5m of age (4-5kg plus) if poss
What heart defect is the most common cause of neonatal cyanosis?
Transposition of great arteries
What other defect accompanies a truncus arteriosus?
Large VSD
What does tricuspid lead to and what does it require for viability?
Leads to Hypoplastic RV
Needs both ASD and VSD for viability
What is the spot diagnosis for cyanotic heart defect presenting with heart taking up while thorax on CXR?
Ebsteins anomaly
