Lesson 11 and 12

Lesson 11 Partitioning of the Heart (Fetal Development) MacNeil 1. What does the entire heart tube raise from? a. Splanchnic mesoderm of the lateral plate mesoderm b. Somatic mesoderm of the lateral plate mesoderm c. Intermediate mesoderm d. Endoderm 1. A: The entire heart tube arises from the splanchnic mesoderm layer of the trilaminar disc 2. Which of these is incorrect? a. Blood islands form in the splanchnic layer of the lateral plate mesoderm (above the developing brain) b. A U-shaped endothelial primitive heart tube develops as the blood islands merge c. A single heart tube is created by the fusion of the two sides of the U-shaped endothelial primitive heart tube d. The fusion of the two sides occurs everywhere except the rostral aspect of the tube 2: D: The fusion of the two sides occurs except in the caudal aspect of the tube.

3. What occurs in the caudal and cranial ends of the developing heart?

I. Cranial: Arterial portion, blood flows from truncus arteriosus->aortic sac->aortic arches II. Caudal: Poles remain separated and form venous inflow region of heart (SVC/IVC->Right Atrium) a. I b. II c. I & II d. None of the above 3.C: Cranial is the arterial portion, blood flows from truncus arteriosus->aortic sac->aortic arches & in the caudal section the poles remain separated and form venous inflow region of heart (SVC/IVC which flow to the Right Atrium) 4. Which of these are heart dilations?

I. sinus venosus (coronary sinus) II. primitive atria (trabeculated left and right atria) III. primitive ventricle (left ventricle; trabeculated left ventricles) IV. bulbus cordis (right ventricle; smooth part of the left and right ventricle) V. truncus arteriosus (outflow tract; ascending aorta and the pulmonary trunk). a. I, II, III, IV, V b. I, II, IV, V c. I, II, III d. All of the above 4. D: All of them are heart dilations

5. How does cardiac looping occur? a. Atrial portion grows up & left (atria ends up superior/posterior); ventricular grows down & right ( ventricles end up anterior/inferior); heart is more left b. Atrial portion grows down & right ( ventricles end up anterior/inferior); ventricular grows up & left (atria ends up superior/posterior); heart is more left c. Atrial portion grows up & left (atria ends up superior/posterior); ventricular grows down & right ( ventricles end up anterior/inferior); heart is more right d. Atrial portion grows down & right ( ventricles end up anterior/inferior); ventricular grows up & left (atria ends up superior/posterior); heart is more right 5. A: During looping, the atrial portion grows upward and to the left, while the ventricular region grows downward and to the right. This places the atria superiorly and posteriorly, the ventricles anteriorly and inferiorly, and the heart itself to the left side of the body.

6. What is true about development and flow of the cardiac chambers (separation of the heart)?

I. Single heart tube is divided into atria and ventricle via atrioventricular canal II. Venous tributaries of sinus venosus -flow into-> primordial atrium, atrioventricular canal, and primordial ventricle -flow into-> inflow tract III. Bulbous cordis/truncus arteriosus -flow into-> aortic sac -flow into-> aortic arch vessels a. I b. I & II c. I, II, & III d. I & III 6. D: I & III are true. For II: Venous tributaries of sinus venosus -> primordial atrium, atrioventricular canal, and primordial ventricle -> outflow tract 7. What does the initial partial septation of the atria not allow? a. it allows blood to be shunted from right to left atria during fetal development b. it allows blood to be shunted from left to right atria during fetal development c. it separates the systemic circulation from the pulmonary circulation d. it divides the atria and common atrioventricular canal into right & left canals 7: B is wrong (it shunts right to left): A, C, & D are true. In order to separate systemic circulation from pulmonary circulation, division of the primordial atria and the common atrioventricular canal to right and left canals is required. Initially, the septation of the atria is a partial separation that allows blood to be shunted from right to left atria during fetal development.

8. What is not true about endocardial cushion tissues that form around the atrioventricular (AV) canal? a. It creates ventral (inferior), dorsal (superior), and two lateral cushions which are extracellular matrix and divide further into the lumen of the AV canal b. The upper and lower (superior/inferior) cushions fuse to form the atrioventricular septum that divides the common AV canal into right and left AV canals c. The muscular tissue of the AV canal leaves behind connective tissue covering in endocardium and connected by chordae tendinae to papillary muscles d. The valve development in the AV canal creates only the tricuspid valve on the right side 8. D: A, B, & C are true, The valve development in the atrioventricular canal results in the tricuspid valve on the right side AND bicuspid on the left side.

9. What is incorrect about atrial septation? a. Growth of two overlapping septa to create an opening with a valve b. Allow blood flow during prenatal period + a way to close the shunt after birth c. Primary foramen between septum secundum and endocardial cushion d. Fusion of the septum primum during week 6 and a second hole that still allows blood to flow 9. C: Primary foramen is a opening between septum primum and endocardial cushion. Septum secondum does not reach the endocardial cushions and instead forms an opening called the foramen oval (in right atrium). A, B, & D are correct.

10. What is true regarding septum secundum development? a. It forms in the inferior right atrium & grows caudally b. It is adjacent to the septum premium of which the lower part becomes the valve for the foramen ovale c. It forms the foramen ovale with the endocardial cushions with shuts due to pressure at birth d. b and c 10. D: It forms in the superior right atrium. Septum secundum does grow caudally. B & C are true.

11. Separation of the outflow tract and ventricles is best described as: a. Division by growth of neural crest-derived ridges that grow near the bulbous cordis/truncus arteriosus b. Twisting of swelling that fuse to form the aorticopulmonary septum which separates ventricular outflow into aortic and pulmonary channels c. Division by growth of splanchnic mesoderm-derived ridges that grow near the bulbous cordis/ truncus arteriosus d. Twisting of swelling that diverge to form the aorticopulmonary septum which separates ventricular outflow into aortic and pulmonary channels 11. A: Division by growth of neural crest-derived ridges that grow near the bulbous cordis/ truncus arteriosus is accurate. For B, & D: Twisting of swelling that fuse to form the aorticopulmonary septum which separates ventricular outflow into aortic and pulmonary channels 12. Neural crest cells are sensitive to toxins such as retinoids, alcohol, and other substances due to a lack of enzymes that help protect from free radicals. Because neural crest cells are important in heart septation and bone formation, this can help explain why: a. children with nervous system defects also have cardiac defects b. children with craniofacial defects also have cardiac defects c. children with craniofacial defects also have skeletal defects d. children with nervous system defects also have skeletal defects 12. B: The fact that crest cells participate in heart septation and that they contribute to the bone of the visceral skeleton and some of the skull explains why many children with craniofacial defects (e.g., cleft lip or palate) also have cardiac defects.

13. The inner walls of developing ventricles fuse to form the ________ septum and the space in-between the muscular interventiruclar septum and endocardial tissues allows for interventricular communication. This space is then filled with endocardial tissue which fuses with conotruncal swellings to form the __________ ventricular septum. Fusion of both septum forms the ___________ septum. a. membranous; muscular; interventricular b. muscular; muscular; interventricular c. membranous; membranous; interventricular d. muscular; membranous; interventricular 13. D: Muscular septum: R + L inner walls of ventricles fuse Inter ventricular communication: Prior to membranous septum growing in Membranous septum: Endocardial tissue + conotruncal swelling fuse Inter ventricular septum: Muscular septum + Membranous septum fuse The inner walls of developing ventricles fuse to form the muscular septum and the space inbetween the muscular interventricular septum and endocardial tissues allows for interventricular communication. This space is then replaced by endocardial tissue which fuses with conotruncal swellings to form the membranous ventricular septum. Fusion of both septum forms the interventricular septum.

Lesson 12 Abnormal Fetal Development MacNeil

1. a. b. c. d.

1.

What is the first organ system to function during development?

Nervous system Gastrointestinal system Cardiovascular system Musculoskeletal system C: Cardiovascular system “The cardiovascular system is the first organ system to function in the developing embryo.”

2. When is the heart fully formed? a. Before week 2 of development b. Beginning of embryonic period c. End of embryonic period d. After birth 2. C: The heart is fully formed by the end of the embryonic period following a complex development.

3. What does the development of the heart include?

I. Fusion of heart tubes II. Leftward looping III. Rightward looping IV. Differentiation of chambers V. Development of coronary vessels & conduction system a. I,II, IV, V b. I, II, IV, V c. II, IV, V d. I, III, IV, V

3. D: The complex development of the heart includes fusion of the heart tubes, rightward looping, differentiation of the chambers and the development of the coronary vessels and conduction system.

4. Congenital heart disease is I. term used to describe abnormalities of the heart or great vessels that are present at birth II. the most common congenital anomaly in newborns III. present in .1% of live births a. I b. I, II c. II, III d. I, II, III 4. B: Congenital heart disease is the general term used to describe abnormalities of the heart or great vessels that are present at birth. Congenital heart defects represent the most common congenital anomaly in newborns and occur in almost 1% of live births.

5. Which of the abnormalities below are congenital cardiovascular anomalies?

I. Ventricular septal defect & Atrial septal defect II. Patent ductus arteriosus & Truncus arteriosus III. Tetralogy of Fallot & Tricuspid atresia IV. Pulmonary stenosis & Aortic Stenosis V. Coarctation of the aorta & Complete transposition of the great arteries a. I, II, III b. I, II, III, V c. I , II, V d. I, II, III, IV, V 5. D: All of the above (don’t memorize ranges) Ventricular septal defects: 25- 30%, Atrial septal defects: 10%-15%, Patent ductus arteriosus: 10%-20%, Tetralogy of Fallot: 4%-9%, Pulmonary stenosis: 5%-7%, Coarctation of the aorta: 5%-7%, Aortic Stenosis: 4%-6%, Complete transposition of the great arteries: 4%-10%, Truncus arteriosus: 2%, Tricuspid atresia: 2% 6. What are the contemporary classifications for heart disease involving initial left to right shunt?

I. Ventricular septal defect,Atrial septal defect, Patent ductus arteriosus, Persistent truncus arteriosus, Anomalous pulmonary venous drainage II. Tetralogy of Fallot & Tricuspid atresia III. Complete transposition of the great arteries, Coarctation of the aorta, Pulmonary stenosis Aortic stenosis, Coronary artery origin from pulmonary artery, Ebstein malformation, Complete heart block a. I b. II c. III d. I & II 6. A: I Initial Left to Right shunt involves: Ventricular septal defect, Atrial septal defect, Patent ductus arteriosus, Persistent truncus arteriosus, Anomalous pulmonary venous drainage (VSD,ASD,PDA,PTA,APVD)

7. What are the contemporary classifications for heart disease involving right to left shunt?

I. Ventricular septal defect,Atrial septal defect, Patent ductus arteriosus, Persistent truncus arteriosus, Anomalous pulmonary venous drainage II. Tetralogy of Fallot & Tricuspid atresia III. Complete transposition of the great arteries, Coarctation of the aorta, Pulmonary stenosis Aortic stenosis, Coronary artery origin from pulmonary artery, Ebstein malformation, Complete heart block a. II & III b. II c. III d. I & II 7. B: II Right to Left Shunt involves: Tetralogy of Fallot, Tricuspid atresia (the two T’s)

8. . What are the contemporary classifications for heart disease involving no shunt (obstruction)?

I. Ventricular septal defect,Atrial septal defect, Patent ductus arteriosus, Persistent truncus arteriosus, Anomalous pulmonary venous drainage II. Tetralogy of Fallot & Tricuspid atresia III. Complete transposition of the great arteries, Coarctation of the aorta, Pulmonary stenosis Aortic stenosis, Coronary artery origin from pulmonary artery, Ebstein malformation, Complete heart block a. I b. II c. III d. I & II 8. C: III No Shunt (obstruction) involves: Complete transposition of the great arteries, Coarctation of the aorta, Pulmonary stenosis Aortic stenosis, Coronary artery origin from pulmonary artery, Ebstein malformation, Complete heart block 9.Which statement below describes normal atrial septum development? a. Two foramen and two septa allow passage of oxygenated blood from right atrium to left atrium during septum formation. After the septum develops, the foramen ovale allows for right to left blood flow until birth. b. One foramen and two septa allow passage of oxygenated blood from left atrium to right atrium during septum formation. After the septum develops, the foramen ovale allows for right to left blood flow until birth c. Two foramen and two septa allow passage of deoxygenated blood from left atrium to right atrium during septum formation. After the septum develops, the foramen ovale allows for right to left blood flow until birth. d. Two foramen and two septa allow passage of oxygenated blood from left atrium to right atrium during septum formation. After the septum develops, the foramen ovale allows for right to left blood flow until birth.

9. A: The normal development of the atrial septum occurs in a sequence (two foramen, two septa) that allows for the passage of oxygenated blood from the right atrium to the left atrium even as the septum is being formed. The final development of the foramen ovale with its valve allows the right to left flow of blood to continue until birth.

10. Which statement best describes an atrial septum defect? a. A semi-permanent opening in the atrial septum that allows blood to communicate between the left and right atria due to incomplete tissue development b. A fixed opening in the atrial septum that allows blood to communicate between the left and right atria due to incomplete tissue development c. A defect that ranges in severity from life threatening during birth to significantly harmful in childhood d. A defect that ranges in severity from life threatening during birth to asymptomatic until childhood 10.B: An atrial septal defect is an abnormal, fixed opening in the atrial septum that arises during atrial septum formation. The opening allows communication of blood between the left and right atria as a result of incomplete tissue development. Atrial septal defects range in severity from clinically insignificant throughout life or asymptomatic until adulthood to life threatening emergencies at birth.

11. Which of the choices below accurately matches the ASD type with the right description? a. ASD ostium primum type: Accounts for most ASDs, caused by excessive cell death/ resorption of septum primum or inadequate development of the septum secondum leading to deficiency near center of atrial septum b. ASD ostium secundum type: near the AV valves in the endocardial cushion region. c. A Sinus venosus defect: near the entrance of the superior vena cava (upper atrial septum) which might result in pulmonary venous drainage into the right atrium or superior vena cava d. ASD ostium secundum type:near the entrance of the superior vena cava (upper atrial septum) which might result in pulmonary venous drainage into the right atrium or superior vena cava 11. C: A Sinus venosus defect (5%): near the entrance of the superior vena cava (upper atrial septum) which might result in pulmonary venous drainage into the right atrium or superior vena cava, ASD ostium primum type (5-7%): near the AV valves in the endocardial cushion region., ASD ostium secundum type (90%): Accounts for most ASDs, caused by excessive cell death/ resorption of septum primum or inadequate development of the septum secondum leading to deficiency near center of atrial septum 12. What is a patent foramen ovale? a. A deficiency near center of atrial septum caused by excessive cell death/resorption of septum primum or inadequate development of the septum secondum leading to b. A small hole created by an open flap of tissue in the ventricular septum that does not seal after birth c. A fusion of the septum primum with the margin of the foramen ovale d. A small hole created by an open flap of tissue in the atrial septum that does not seal after birth 12. D: A patent foramen ovale is a small hole created by an open flap of tissue in the atrial septum. The tissue derived from the septum primum functions as a flap valve that normally fuses with the margin of the foramen ovale. In the fetus, this was an important functional right to left shunt, passing oxygenated blood (carried in the umbilical vein) from the right atrium directly to the left atrium. After birth, an incomplete seal of the foramen ovale occurs in approximately 25% of adults and is typically asymptomatic. However, with sustained or transient increases in right sided pressures a right to left shunt with possible paradoxical embolism can occur.

13. An interventricular septum typically grows upward from the apex and joint the membranous septum that grows downward. Incomplete closure of this leads to a ventricular septal defect (VSD) which allows left -> right shunt of blood in the ventricles. The severity of defects are based on the size and the most common occurs in the membranous septum. What types of VSD exist? a. A hole in the membranous septum b. Defects limited only to the muscular septum c. Complete absence of the muscular septum d. All of the above 13. d. All of the above

14. Persistent truncus arteriosus is due to a failure of the turns aterious to divide into the aorta and pulmonary trunk thus resulting in a single large artery. What is true about PTA? a. It receives blood from both ventricles and is always associated with a VSD b. Most newborns require heart surgery due to heart failure,recurrent respiratory infections and risk of early death. c. It gives rise to systemic, pulmonary, and coronary circulations d. All of the above 14. D: Persistent truncus arteriosus arises from the failure of the truncus arteriousus to separate into the aorta and pulmonary trunk. The result is a single great artery (due to the lack of the spiral septum forming in the truncus arteriosus) that receives blood from both ventricles and gives rise to systemic, pulmonary and coronary circulations. It is always associated with a VSD and mixing of blood from the right and left ventricles. Most newborns require open heart surgery due to heart failure, recurrent respiratory infections and risk of early death.

15. Here are some facts: 1. the heart has right ventricular hypertrophy and a large VSD caused by incomplete closure of the membranous septum + effects on the muscular septum+endocardial cushions.

2. abnormal development of the aorticopulmonary septum causes the aorta to sit right and over the VSD. 3. (sometimes) the ductus arteriosus is patent.

Based on this, what would be the four cardinal features of the tetralogy of Fallot? a. VSD, pulmonary stenosis, aorta overlying VSD, right ventricular hypertrophy b. VSD, aortic stenosis, aorta overlying VSD, left ventricular hypertrophy c. ASD, aortic stenosis, aorta overlying ASD, right ventricular hypertrophy d. ASD, pulmonary stenosis, aorta overlying ASD, right ventricular hypertrophy 15. A: The 4 cardinal feature include: VSD, pulmonary stenosis, aorta overlying VSD, right ventricular hypertrophy. Typically corrected with surgery in first 2 years of life.

16. Abnormal formation of the aortic pulmonary septum causes transposition of great arteries (TGA) This is usually fatal without a shunt/surgical correction and infants typically also have ASD+patent ductus ateriosus and possibly VSD. What describes the transposition? a. the aorta now arises from the right ventricle (infront/to right of pulmonary artery) which now arises from the left ventricle. b. the aorta now arises from the left ventricle (infront/to right of pulmonary artery) which now arises from the right ventricle. c. the aorta now arises from the right ventricle (behind/to right of pulmonary artery) which now arises from the left ventricle. d. the aorta now arises from the left ventricle (behind/to left of pulmonary artery) which now arises from the right ventricle.

16. A: In transposition of the great arteries (TGA) the aorta arises from the right ventricle and lies anterior and to the right of the pulmonary artery, which arises from the left ventricle.

17. Which is NOT an accurate description of the following congenital aortic stenosis conditions: a. Valvular aortic stenosis: hypoplastic,dysplastic,or abnormal amount of cusps. Most common is bicuspid valve due to abnormal endocardial cushion development. b. Subvalvular aortic stenosis: abnormal band of fibroelastic tissue below cusps due to thick tissue left form ventricular outflow tract. c. Supravalvular aortic stenosis: thickening of ascending aorta causing luminal constriction d. Valvular aortic stenosis: This type of stenosis is often associated with multiple system disorders.

17. D: Supravalvular aortic stenosis is often associated with multiple system disorders. A, B, & C are true. Typically surgical treatment can be done on valvular (replace valve) and subvalvular (remove tissue) aortic stenosis.