USMLE Forum Archives - USMLE Step 2 CK - Peds 8
Peds 8
TheOne - 11-26-06 19:06
A term female infant is found to be cyanotic shortly after birth and requires endotracheal intubation. On physical examination, her blood pressure is 65/35 mm Hg (equal in all four extremities), pulse is 170/min, and respirations are 34/min. Her precordium is dynamic, has a grade III systolic murmur, and a single S2. Chest radiography shows a normal heart size and increased pulmonary vascular markings. An arterial blood gas on an FiO2 of 100% shows pH
7.34; PaCO2, 48 mm Hg; PaO2, 45 mm Hg. Which of the following diagnoses is most consistent with these findings?
A. Atrial septal defect
B. Hypoplastic left heart syndrome
C. Patent ductus arteriosus
D. Tetralogy of Fallot
E. Total anomalous pulmonary venous return
TheOne - 11-26-06 19:06
A term female infant is found to be cyanotic shortly after birth and requires endotracheal intubation. On physical examination, her blood pressure is 65/35 mm Hg (equal in all four extremities), pulse is 170/min, and respirations are 34/min. Her precordium is dynamic, has a grade III systolic murmur, and a single S2. Chest radiography shows a normal heart size and increased pulmonary vascular markings. An arterial blood gas on an FiO2 of 100% shows pH
7.34; PaCO2, 48 mm Hg; PaO2, 45 mm Hg. Which of the following diagnoses is most consistent with these findings?
A. Atrial septal defect
B. Hypoplastic left heart syndrome
C. Patent ductus arteriosus
D. Tetralogy of Fallot
E. Total anomalous pulmonary venous return
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#1
Re: Peds 8 Brainlab - 11-26-06 19:44 It's early cyanotic syndrom, therefore answer A and C are wrong. In spite of the fact that Tetralogy of Fallot is the most common cyanotic heart syndrom it is not right answer in this case. There is right ventricle hypertrophy so bootshape heart on X-ray in Tetralogy of Fallot. Unfortunately I don't know which answer is best in remaining B or E. I am not shure but choose E.
#2
Re: Peds 8 Allen - 11-26-06 20:56 do we have Cyanosis after birth in TOF ? not frequently, as we know Transposition of great Ves. is mostly with cyanosis.which is not in the choices now
besides single S2 and systolic murmur comes with TOF which is the most com. cause of cyanotic heart dz,BUT chest is clear due to pulmonary stenos . Q says inc . pulm. vas. markings. and nl heart size.
in Hypoplastic there is No murmur but Loud S2.
i pick E by chance
#5
Re: Peds 8 Allen - 11-28-06 22:12 my friends opinion :
Mary(11/28/2006 4:33:12 PM): Among all the options,only B causes such a severe picture during the first 24hrs. Rt ventricle has to do all the work while it is not designed to do so, as a result there is not adequate systemic circulation which in turn causes severe met.acidosis shortly after birth. We expect to see cardiomegaly due to Rt Vent hypertrophy very soon. By the way, with normal heart size and shape, you cannot choose any of the options except A which is not the case obviously. Increased pulmonary vascular markings, is in favor of Answer B
#6
Re: Peds 8
TheOne - 12-01-06 15:54 The correct answer is E. Total anomalous pulmonary venous return is characterized by the pulmonary veins forming a confluence behind the left atrium, and draining into the right atrium. Complete mixing takes place in the right atrium, with a right-to-left shunt through the foramen ovale to the left side of the heart. Often, no murmur is heard on cardiac examination, although a short systolic murmur is sometimes heard. ECG often reveals right atrial enlargement and right ventricular hypertrophy. The chest roentgenogram often shows a normal heart size with pulmonary edema. If there is obstruction to pulmonary venous return, as is almost always present with veins draining inferior to the diaphragm, cyanosis can be very prominent. Definitive treatment is surgical anastomosis of the pulmonary vein to the left atrium.
Atrial septal defect (ASD) (choice A) is a hole in the septum between the right and the left atria. It results in a left-to-right shunt and causes right ventricular volume overload and increased pulmonary blood flow. Approximately 3% to 5% of children with congenital heart disease have an ASD, making it the third most common congenital heart defect.
Hypoplastic left heart syndrome (choice B) is characterized by underdevelopment of the left ventricle and the ascending aorta. Typically, there is obstruction at the mitral valve, causing all pulmonary venous blood to shunt through either an ASD or a patent ductus arteriosus (PDA) into the right atrium. Total systemic blood flow is channelled through the ductus arteriosus from the pulmonary artery. As the ductus closes, these infants
present with shock because systemic blood flow is significantly reduced.
PDA (choice C) causes symptoms of pulmonary congestion, dyspnea, widened pulse pressure, and bounding arterial pulsation because aortic blood flow is shunted from left to right.
Tetralogy of Fallot (choice D) consists of four cardinal cardiac defects:
(1) pulmonary stenosis .
(2) ventricular septal defect (VSD).
(3) aorta dextroposition (or overriding aorta).
(4)right ventricular hypertrophy.
(TOF) is one of the most common congenital heart disorders and classified as a cyanotic heart disorder because the condition results in an inadequate flow of oxygenated blood to the systemic circulation. Patients with TOF initially present with cyanosis shortly after birth, thereby requiring early medical attention.
#8
Re: Peds 8 bingousmle - 07-19-10 08:48 increased pulmonary vascular markings and single S2 means there is pulmonary hypertension with a low PaO2 means there is mixing of blood so Total anomalous pulmonary venous return
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