[drmodi44]

a 5 yr old child develops cyanosis with minimal exertion and frequently assumes squatting position,on medical evaluation, he is found to hv enlarged RT ventricle which of the following early developmental events most likely underlies this condition?
A) abnormal neural crest migration
B) endocardial cushion defect
C) aortic arch constriction
D) pulmonary HT
E) abnormal primitive heart tube looping

 

[donofitaly]

The condition is Tetralogy of Fallot and i think the option above which is correct is abnormal primitive heart tube looping.

 

[Seetal]

hmm... he's 5 and squatting with RVH. could be a VSD and squatting improves venous return in this child. so im guessing endocardial cushion defect??

 

[drmodi44]

A ia correct....

correct answer is A...
here cardiac abnormality could be one of 3 (TOF, truncus arteriosus, transposition of great vessel)
division of primitive truncus arteriosus and bulbar cordis into the aorta and pul artery which is accomplished by the process of aortico pulmonary sepatation requires neural crest cells to migrate into the truncal & bulbar ridges of truncus arteriosus & bulbar cordis respectively and grow in a spiraling fashion to separate the aorta and pulmonary artery,failure of this process is responsible for TOF,truncus arteriosus & transposition of great vessels