Abnormal CV Development Flashcards
Where do most CHD defects arise?
Faulty embryogenesis (weeks 3-8)
What are the most common causes of CHD?
90% - unknown 9% - genetic -Gene defects [ex: marfan] 2-3% familial -Chromosome defects - 5% gametogenic, non-familial 1% - environmental -Rubella (patent ductus arteriosus) -Chemical (thalidomide, ETOH)
What is a shunt?
Abnormal communications leads to blood flow diversions
What conditions are associated with a Left to Right shunt?
Cyanosis several months or years after birth [blue kids]
- Atrial septal defect
- Ventricular septal defect
- Patent (persistent) ductus arteriosus
What conditions are associated with a Right to Left shunt?
Cyanosis early in postnatal life [blue babies!]
- Tetralogy of Fallot
- Transposition of the great arteries/vessels (TGA)
- Truncus arteriosus (persistent or common trunk)
What shunts have cyanosis and which do not (cyanosis tradive)?
Right to left shunts = cyanotic
Left to right shunts = no cyanosis
What is cyanosis defined as?
Oxygen saturation below 75%
When do multiple or combination of defects occur in CHD?
-Teratogens or bc of blood flow needs
Ex: pulmonary stenosis may be associated with atrial septal defect and patent ductus arterioles or interventricular septal defect
What is normal pressure in the pulmonary artery vs aorta?
1 vs 6
What can shunt pressure cause?
- Increased right ventricular or pulmonary artery pressure leads to pulmonary fibrosis
- Late right ventricular failure may lead to reversed flow (ex: ventricular septal defect)
What causes obstructions (stenosis or atresia)?
- Stressed ventricles lead to ventricular failure
- Shunts may be required for survival
What is an atrial septal defect (ASD)?
L to R
- An abnormal opening between the right and left atria
- Normal: flap over foramen ovale; R –> L shunt (fetus); closed adult
- Abnormalities usually result because of incorrect development of the atrial septum.
What usually causes incorrect development of the atrial septum? (90% cases)
-Excessive resorption of the primary septum or large secondary foramen
-Incompetent foramen ovale due to hypoplastic growth of the secondary septum (large foramen ovale) and/or excessive resorption of primary septum
[Above two = 90%]
What usually causes incorrect development of the atrial septum? (5% cases)
- Inadequate development of the primary septum producing a basal opening known as a primary foramen defect (premium anomaly) (5%)
- Sinus venous developmental defect with high atrial septal defect (5%)
What generally occurs in all atrial septal defects (ASD)?
Left to right shunting of blood.
What physiology is associated with ASD?
- Pulmonary blood flow may be 2-4 times normal
- Amount of blood flow is size-dependent
- Only large ones lead to pulmonary hypertension that leads to cyanosis tardive and cardiac failure
What are the complications of ASD?
- RV failure
- Paradoxical embolism (and brain infarction or abscess)
Rx:
Surgery, if large (patch foramen) to close atrial septal defect
Which of the following is the most common form of ASD?
Patent foramen ovale
What is the most common form of congenital heart defect?
Interventricular septal defect!
-40% of congenital heart abnormalities
What is unique about VSD (ventricular septal defects)?
- Size variable; symptoms = size
- 90% involve the membranous portion of the ventricular septum; muscular septum involvement may exhibit multiple sites (Swiss-cheese septum)
- Murmur/size (50% close spontaneously)
- Cyanosis tardive in long-standing cases
What other abnormalities may be combined with VSD?
- Pulmonary stenosis
- Tetralogoy of Fallot
- Coarctation of aorta
- Transposition of aorta
What is the treatment for VSD?
Surgery
What is responsible for most forms of VSDs?
Abnormal formation of the endocardial cushions and aorticopulmonary septum
What is the significance of the ductus arteriosus?
- It develops from the 6th aortic arch and connects the left pulmonary trunk to the aorta
- During fetal if it serves to direct blood from the pulmonary artery to the aorta
What is Patent (Persistent) Ductus Arteriosus (PDA)?
- During fetal life this hole directs blood from the pulmonary artery to the aorta
- Normal: flow decreases on day 1; ligamentous structure by day 30
- -If the ductus remains patent after birth, the direction of blood flow is form the aorta to the pulmonary artery
- -Reversed blood flow causes cardiac enlargement and increased pulmonary vascularity
What congenital CV abnormality is associated with maternal rubella (german measles) during early pregnancy?
(weeks 1-8)
Patent Ductus Arteriosus.
Other defects caused by maternal rubella:
-Congenital cataracts
-Deafness due to involvement of inner ear
-Pulmonary stenosis (PS)
-Ventricular septal defect (VSD)
What type of murmur does PDA cause?
“Machinery-like” murmur (thrill?)
What are clinical complications of PDA?
- Infective endocarditis common
- Pulmonary hypertension common
What is the treatment for PDA?
Surgery
- Cardiologist: catheter-placed occluder
- Medical: Ibuprofen in pre-matures
What four defects are associated with Tetralogy of Fallot (TF)?
- Ventricular septal defect
- Pulmonary stenosis
- Overriding (large) aorta
- Right ventricular hypertrophy
What are clinical signs of TF?
- Cyanosis dependent on size of ventricular septal defect; cyanosis may be absent early
- Murmur due to pulmonary stenosis
What are the complications associated with TF? How to treat TF?
-Paradoxical embolism (brain abscess)
-Infective endocarditis
Treatment = surgery
What causes TGA (Transposition of the Great Arteries)?
It’s caused by a failure of the normal spiraling of the aorticopulmonary septum [causing straight divison of the bulbus cordis and truncus arteriosus]
-As a result, aorta originate from the right ventricle and the pulmonary artery from the left ventricle
What shunts are common in TGA?
- Atrial septal defect
- Ventricular septal defect
- Patent ductus arteriosus
What is the outcome of TGA? Who gets it?
Outcome: incompatible with life unless an atrial and ventricular septal defect and an associated patent ductus arteriosus are present.
-M/F = 3/1; malformation particularly common in offspring of diabetic mother
What is the best treatment for TGA?
Early surgery
What is Truncus Arteriosus (Persistent)?
TA - A common aorticopulmonary outlet, receiving blood from both ventricles
What causes TA?
Failure of the bulbar and truncal ridges (aorticopulmonary septum) to develop
What is the pathogenesis of TA?
Since there is a mixing of blood from the right and left ventricles, cyanosis is present, and there is an increased pulmonary blood flow leading to irreversible pulmonary hypertension.
What do all Right –> Left shunts involve a malformation of?
Aorticopulmonary septum
Which defects involve the bulbar and truncal ridges?
- Common or persistent truncus
- Tetralogy of Fallot
- Transposition of the great arteries (TGA)
What are three Acyanotic Obstructions?
- Coarctation of Aorta
- Pulmonary Stenosis and Atresia
- Aortic Stenosis and Atresia
What is coarctation of the aorta?
Characterized by a narrowed aortic lumen (Obstructive congenital heart disease) – infolding of the aorta opposite the closed ductus arteriosus (DA)
What do you see in Postductal (adult form) of Coarctation of the Aorta?
- Common (95%); twice as common in males as females
- BP in arms increased (normal flow to head & upper body)
- BP in legs decreased (dec. flow to lower extremities)
- Intercostal artery blood flow increased (notched ribs)
- Hypertension in upper extremities; weak pulse and low bp in the lower extremities
What complications are associated with Postductal Coarctation?
- Congestive heart failure
- Cerebrovascular accident
- Rupture
- Infection
What treatments are available for Postductal Coarctation?
Excision, Bypass.
Experimental: Balloon angioplasty
What is Preductal Coarctation of the Aorta?
(Infantile form) - 5%
- Tubular hypoplasia of the aortic arch proximal to a patent ductus arteriosus:
- -Early CHF (congestive heart failure)
- -Patent ductus arteriosus
- -Cyanosis, lower body
- -Mortality increased
Pulmonary/Aortic Stenosis and Atresia:
Aortic or pulmonary stenosis and atresia.
-Due to asymmetrical division or spiraling of the aorticopulmonary septum
(bulbar and truncal ridges)
13 yr old boy. No femoral pulses. Increase bp in upper extremities. Enlarged intercostal vessels. What is suspected?
Postductal coarctation of the aorta
What congenital defect is maternal diabetes associated with?
Transposition of the great arteries
What congenital defects is DiGeorge Syndrome associated with?
Deletion chromosome 22q11 - involved with neural crest cells
- Tetralogy of Fallot
- Truncus arteriosus (Persistent)
What is Down syndrome (trisomy 21) associated with?
Atrial septal defect
Ventricular septal defect
What is Turner syndrome (45, XO) associated with?
Coarctation of the aorta
What is Marfan syndrome (fibrin-1 glycoprotein abnormality, FBN1 gene; chromosomes 15q21.1 and 5q23.31) associated with?
Aortic stenosis
Newborn baby becomes cyanotic over a few hours. Oxygen saturation in veins and arteries is similar. What CV abnormality is most likely responsible for the baby’s cyanosis?
Endocardial cushion defect
