q3 - step1mom

[ArchivalUser]

A 2-month-old male is brought to the pediatrician
by his mother who is concerned that he is
not gaining weight. She also notes that his
color is poor, especially when he tries to feed,
when he often grunts and turns dusky. Which
of the following cardiac lesions is most likely
to cause the patient™s symptoms?
(A) Atrial septal defect
(B) Patent ductus arteriosus
© Patent foramen ovale
(D) Tetralogy of Fallot
(E) Ventricular septal defect

[ArchivalUser]

PDA ?
Tetra?

[ArchivalUser]

(D) is correct. The Tetralogy of Fallot is the most
common cause of cyanotic heart disease in which
blood bypasses the lungs and mixes with oxygenated
blood. Four lesions comprise the Tetralogy of Fallot:
origin of the aorta is the right ventricle, pulmonary
artery stenosis, ventricular septal defect, right
ventricular hypertrophy. As much as 75% of venous
return to the heart is passed, unoxygenated, from the
right ventricle to the aorta and the systemic circulation,
resulting in cyanosis.
Explanation A: No. An atrial septal defect results in a
left-to-right shunt of blood from the higher pressure
left side of the heart to the lower pressure right atrium.
There is no cyanosis as there is no mixing of venous
blood with oxygenated blood from the left side of the
heart.
Explanation B: No. The ductus arteriosus is a
connection of the pulmonary artery with the aorta used
in fetal life to obviate blood flow through the lungs. If
this structure does not close soon after birth there is
persistent left-to-right shunt of blood from the higher
pressure aorta into the pulmonary veins, but no
cyanosis.
Explanation C: No. A patent foramen ovale functions
as an atrial septal defect with a small left-to-right shunt
of blood without cyanosis.
Explanation E: No. In a ventricular septal defect, blood
flows from the higher pressure left ventricle to the lower
pressure right ventricle, a left-to-right shunt of blood
without cyanosis.

[ArchivalUser]

answer is D . TOF . child is cyanotic n breathless.