Frequently asked questions in Pediatric Cardiology

Q. What is the saturation content of various fetal structures?

Ans. Umbilical vein (80%) > IVC (70%) > LV (65%) > RV (60%) > UA (below 50%)

Q. What is the PO content in major fetal structures? 2

Ans.

• Umbilical vein has 30-35 mm Hg
• IVC has 26-28 mm Hg
• SVC has 12-14 mm Hg
• LV and ascending aorta has 26-28 mm Hg
• Descending aorta has 24 mm Hg
  • Descending aorta has blood from LV and RV blood (from ductus arteriosus)
  • Thus, the head & neck, and upper limb receive better oxygenation than the lower limb and internal organs
    • Due to vessel arising from ascending aorta

Also read: NEET SS Pediatrics: Important Pediatric Pulmonology Topics 2025

Q. Which structure diverts IVC blood from reaching RA into LA via foramen ovale?

Ans. Eustachian Valve and Crista dividends.

Q. What is the fate of UV blood?

Ans. 50% goes into the liver, and 50% goes into IVC via ductus venosus.

Q. What is the fate of descending Aorta blood?

Ans.

• 65% returns to the placenta, and 35% perfuses the fetal organs and tissues
• It is then returned back through the inferior vena cava.

Q. What are the ventricular dimensions in the fetus?

Ans.

• Since RV output is 1.3 times LV output in a fetus and handles more blood,
• The RV wall is thicker than the LV in the fetal and first few days of post-natal life.

Also read: NEET SS Pediatrics 2025: Must-Know Pediatric Cardiology Topics

Q. What percentage of the total ventricular output is handled in the fetus by the two ventricles individually?

Ans. RV handles 55%, whereas the left ventricle handles 45%.

Q. Why does fetal distress produce a fall in cardiac output?

Ans.

• Cardiac output = Heart Rate × Stroke Volume
• In the case of adults, whenever there is bradycardia
  • The stroke volume increases proportionately, so the cardiac output is maintained.
• In the case of the fetus and the early neonatal period,
  • Distress in the fetus or hypoxia will produce bradycardia.
  • Still, in these patients, the stroke volume fails to rise
    • Due to low compliance of the fetal heart → cardiac output tends to fall
    • Leading to the appearance of a shock-like state in the patient.

Q. Preterm babies have a higher risk of PDA. Why?

Ans. There are majorly two reasons:

• The ductal smooth muscle in preterm babies does not show a constrictor response to oxygen.
• These babies have relatively higher PGE2 levels due to decreased lung degradation.

Q. Why do preterm babies have early onset CCF in PDA?

Ans. The pulmonary vascular smooth muscle is not as well developed as in full-term infants. So PVR falls very rapidly, and the L→R shunt starts early.

• In preterm babies with HMD
  • Will develop hypoxia and have late CCF in PDA.
• In preterm babies with no respiratory illness
  • Rapid fall in pulmonary vascular resistance, leading to early CCF in PDA.

Also read: Liver Abscess & Liver Disease Systemic Illness In Children

Q. A CXR done in a cyanotic infant showed the typical boot-shaped heart. Which next investigation will be helpful to see if it's TOF or Tricuspid Atresia, if echocardiography is not available immediately?

Ans.

• When a CXR showing a boot-shaped heart is obtained, echocardiography is immediately performed. Since it is not available, an ECG is performed. If the ECG shows
  • Features of RVH → Tetralogy of Fallot
  • Features of LVH → Tricuspid Atresia.

Q. Which of the following is a ductus-dependent lesion?

1. TGA
2. TAPVC
3. ECD
4. Supracristal VSD

Ans. A) TGA

Q. Which of the following is a ductus-dependent lesion?

1. TGA
2. Tricuspid atresia
3. ECD
4. Supracristal VSD

Since most varieties of TGA have VSD. TGA with intact ventricular septum – only ductus-dependent form of TGA.

Ans. B) Tricuspid atresia

Q. A neonate developed shock, absent pulses, and poor perfusion on day 2 of life. Sepsis markers were negative, and there was a poor response to Dopamine & Epinephrine. On doing echocardiography, a specific abnormality in the heart was detected, for which Alprostadil infusion was started, and there was a dramatic improvement in his clinical status. What could not have been the likely CHD?

1. Hypoplastic left heart syndrome
2. Hypoplastic right heart syndrome
3. Severe critical coarctation of aorta
4. Interrupted aortic arch syndrome

Ans. B) Hypoplastic right heart syndrome

Also read: Ebstein's Anomaly In Children

Q. Why is PDA more common in preterm and LBW babies?

Ans. The smooth muscle in the wall of the preterm ductus is less responsive to high PO2 . Thus, it is less likely to constrict after birth.. The valve structure of DA is normal in preterm newborns. Only its reactivity to oxygen is reduced

Q. Which age group shows maximum chances of restenosis or re-coarctation?

Ans. Surgery done in infancy (before 1 year) shows maximum chances of restenosis, but this does not mean that you delay the surgery.

Q. What is the procedure of choice if re-coarctation occurs?

Ans. Balloon angioplasty is the first-line treatment performed.

• Balloon angioplasty as a secondary procedure after initial surgery does not increase the chance of damage, rupture, or aneurysm formation.
• It is, therefore, the method of choice once post-surgical re-coarctation has happened.

Q. What are the CNS complications associated with CoA?

Ans. They are related to the formation of CNS haemorrhage, including haemorrhagic stroke.

Q. If the CoA is uncorrected, how long will the patient survive?

Ans. The patient will survive for 20-40 years. There are cases where they have survived for longer, but there are LV dysfunctions seen, due to which the patient will die because of uncorrected cardiac failure. The patients have been candidates for cardiac transplants.

Also read: Arrhythmias: Drug Principles And Indications

Q. What happens if the fontan procedures fail?

Ans. A heart-lung transplant is needed. If some of the patients benefit from heart transplants alone or, in the case of cirrhosis, a liver transplant can be carried out.

Q. Look at the Echo image of the parasternal long-axis view in a 7-month-old infant showing Multiple ventricular masses and tell the likely diagnosis?

Ans. The most likely diagnosis is Rhabdomyoma.

Q. IE is strongly suspected in a child. But blood cultures sterile possibilities?

Ans.

• Antimicrobial given prior to presentation.
• Fungal sepsis.
• Infection with fastidious/Atypical microbes: Brucella, Bartonella, HACEK group and Chlamydia.
• Improper blood collection for culture.

Hope you found this blog helpful for your E-learning for NEET SS Pediatrics. For more informative and interesting posts like these, keep reading PrepLadder’s blogs. 

Download PrepLadder's best app for neet ss preparation for Android 

Download PrepLadder's best app for neet ss preparation for ios