Cardiology Flashcards
Where does the heart arise from?
Mesoderm
By which week is heart formation complete?
7-8 weeks
Which organ received the greatest amount of fetal cardiac blood flow?
Placenta (45%)
When do most cardiac abnormalities develop by?
Week 8, during embryogenesis
Patency of the ductus arteriosus in utero is maintained by?
Prostaglandins (PGE-2)
Prostacyclin (PGI2)
Thromboxane A2
Note: Postnatally PGE-1 is the IV prostaglandin used for ductal patency
Which factor determines the width of the ductus arteriosus in utero?
The amount of flow.
In right sided obstructive lesions with low flow, the PDA will be narrow. Opposite is true for L sided obstructive lesions.
Dominant ventricle in utero?
Right ventricle. Responsible for 65-70% of total cardiac output
Where is the highest oxygen content in the fetus?
Umbilical veins, oxygen saturation 70-80%
Factors leading to postnatal closure of PDA?
- Higher O2 content of room air
- Bradykinin in the lungs
- Lower prostaglandin E (loss of placental production and increase in breakdown by the lungs)
Definition of cardiac output
Volume of blood ejected from the ventricle per minute
Formula for cardiac output
Stroke volume x HR
Systemic blood pressure/total peripheral vascular resistance
Factors leading to increase in cardiac output
Increase in heart rate Increase in stroke volume -> this is achieved by: Increase in preload Increase in contractility Decrease in afterload
What does Qp/Qs >1 mean?
L to R shunt. If greater than 2, very large shunt
What does Qp/Qs <1 mean?
R to L shunt. If less than 0.7, very large shunt
Most common congenital heart defect?
VSD
Most common CHD beyond infancy?
TOF
Most common CHD to present in the 1st week of life?
TGA
Which CHD is the most common cause of mortality in the 1st week of life?
HLHS
Also the 2nd most common CHD presenting in the 1st week of life, after TGA
Name the cyanotic CHDs (hint: there are 9)
5 Ts, DO, ESP
5 Ts: Transposition, TOF, Truncus, Tricuspid atresia, TAPVR
DO: Double Outlet RV
ESP: Ebstein’s anomaly, Single ventricle, Pulmonary atresia
Ebstein’s anomaly is associated with an increased risk of?
Pulmonary hypoplasia because of large R heart in utero
Single ventricle is associated with an increased risk of?
Asplenia or polysplenia
Most common type of TAPVR?
Supracardiac (drain into SVC)
Most common type of TAPVR to be obstructive?
Infracardiac (subdiaphragmatic)
Presents with cyanosis, respiratory distress (requiring intubation soon after birth), decreased systemic perfusion
Snowman silhouette on CXR
Supracardiac TAPVR
What determines the clinical symptoms in DORV?
Presence or absence of VSD and pulmonic stenosis
VSD needed for blood flow out of the LV
Pulmonic stenosis determines the pulmonary blood flow (and overcirculation)
MCC of congestive heart failure after the 2nd week of age?
VSD
Most common type of VSD?
Perimembranous (70%)
Out of these, trabecular region is most common
When does functional closure of PDA occur and what is it dependent on?
Occurs by 48 hours (2 days) of age in 90% of term infants
It depends on vasoconstriction in the medial smooth muscles
When does anatomical closure of the PDA occur and what is it dependent on?
Occurs by 2-4 weeks of age
Depends on low blood flow through the lumen, relative hypoxia
PDA dilators?
Prostaglandin E1, prostaglandin I2 (prostacyclin), acidosis, hypoxemia
PDA constrictors?
Bradykinin, oxygen, acetylcholine, PGF2
What are term infants with a persistent PDA at risk for?
Recurrent pneumatosis
Type of ASD and VSD in AVCD?
Ostium primum ASD
Inlet VSD
Common AV valve
What other cardiac anomalies is an aortic coarctation associated with?
Bicuspid aortic valve, VSD
30% of patients have Turner’s
Most common location for pulmonic stenosis?
Valvular
What kind of pulmonic stenosis is associated with TOF?
Subvalvular/infundibular
What kind of pulmonic stenosis is associated with Williams syndrome and rubella?
Supravalvular
Where does the L main coronary artery arise from in ALCAPA?
Pulmonary artery
What’s the most common primary cardiac tumor in neonates?
Rhabdomyoma
What conditions is hypertrophic cardiomyopathy seen with?
Noonan syndrome, Pompe’s, Hurler
Also in IDM and postnatal steroids
Most common neonatal tachyarrhythmia?
SVT (70-80%)
What does the development of hydrops in SVT depend on?
Duration of tachycardia (does NOT depend on rate of SVT)
Degree of immaturity
1st line intrauterine management for SVT?
Digoxin
Can also use flecainide or amiodarone
Side effects of antiarrhythmics to monitor for in the neonate
Hyperbilirubinemia
Anemia from bone marrow suppression
Higher risk for NEC
What is an AV block in a fetus with otherwise normal cardiac anatomy associated with?
Maternal SSA or SSB antibodies
When would you see reverse differential cyanosis?
D-TGA, PDA and one or more of the following: PPHN, coarctation of the aorta, or an interrupted arch
What causes the widely fixed, split second heart sound in ASD?
Delayed RV depolarization, and little change in venous return to the R atrium with respiration
Which vessels in the fetus have the highest and lowest oxygen content?
Highest is in umbilical vein
Lowest is in SVC (high brain extraction)
Normal position designation of cardiac structures?
S (atria), D (ventricles), S (great arteries)
Why is the oxygen content in the SVC low?
Because of high extraction by the brain
Most common cause of complete vascular ring?
Double aortic arch, results from prevailing R and L 4th branchial arches
Mechanism of action of milrinone
PDE3 inhibitor
Inotrope, decreases afterload
Mechanism of action of digoxin
Inhibits Na/K ATPase pump
Negative chronotrope
+ inotrope
Which receptors does dobutamine act on
B1»B2, little activity on A
+Chronotrope and Inotrope
Which receptors does dopamine act on
Low dose: dopaminergic
2-6: B1 and dopaminergic: inotropic and inc HR
6-20: B1 and some A1
>20 A1
Causes release of endogenous norepi, so less effective with prolonged use
Which receptors does epinephrine
B1 and B2>A1
SVR effect is dose dependent (increases with increasing A1 activity)
Rashkind procedure
Increase foramen ovale size for improving inter-atrial mixing (eg in D-TGA)
BT shunt
Subclavian artery to pulmonary artery conduit (in cases of inadequate pulmonary flow)
Eg: Pulmonary atresia, Pulmonary stenosis, TOF
Most common pediatric symptomatic arrhythmia
SVT
Most common cardiac anomalies in VACTERL
VSD
Most common cause of HTN in a neonate
Renovascular disease
When is fetal congenital heart block in maternal SLE diagnosed?
16-24 weeks in utero
When do maternal SLE antibodies disappear from the baby?
6-8 months of life
The effect of epinephrine during neonatal resuscitation is a result of stimulation of mainly which receptors?
Alpha-adrenergic receptors and the peripheral vasoconstriction
Which receptor are infantile hemangiomas associated with?
GLUT-1
Preferred vasoactive treatment for septic shock>
Norepinephrine
