CTVS Q24- 30

CTVS MCQs -24 to 30

Questions 1-7

Questions 8-12

Questions 13-18

 Questions 19-23

Q 24 Contraindication of Fontan procedure?

a) 20 year old male

b) Severe MR

c) Right pulmonary artery stenosis

d) Left ventricular end diastolic pressure of 20 mm Hg

24) d

Fontan procedure is for tricuspid atresia and is done when there is low pulmonary vascular resistance. For the same reason it is not done in neonates. 

In Tricuspid atresia, venous blood does not go to right ventricle and there is mixing of venous and arterial blood in aorta which leads to decreased oxygenation.

Most infants with tricuspid atresia have restrictive pulmonary blood flow.  To improve systemic oxygentaion they undergo modified Blalock-Taussig shunt, which is a small polytetrafluoroethylene (PTFE) graft to connect the subclavian artery and a pulmonary artery.

Criteria for Fontan procedure are 

  • Age older than 4 years
  • Sinus rhythm
  • Normal systemic venous return
  • Normal right atrial volume
  • Mean pulmonary artery pressure less than 15 mm 
  • Pulmonary arteriolar resistance less than 4 Wood units/m 2
  • Pulmonary artery–aorta ratio more than 0.75
  • Left ventricular ejection fraction more than 0.60

Current absolute contraindications are a pulmonary vascular resistance above 4 Wood units/m2, severe hypoplasia of the pulmonary arteries, and severe diastolic dysfunction of the left ventricle.

Q25  Autopsy finding  in a patient who dies of Tetrology of Fallot is

a)  Brachiocephalic vein draining into the left renal vein
b)  Inferior vena cava (IVC) draining to the superior mesenteric vein
c)  Atrial Septal Defect (ASD)
d) Decreased vascularity of the lung field

25) d

Decreased vascularity of lungs

Tetralogy of Fallot includes
VSD, right ventricular outflow obstruction,
dextroposition of the aorta, and right ventricular
hypertrophy. Tetralogy of Fallot accounts
for over one-half the cases of congenital cyanotic
heart disease.

Q26. Which of the following statements about VSDs is wrong ?

A. Spontaneous closure of VSDs occurs in 25% to 50% of patients during  childhood.
B. Tachypnea and failure to thrive are symptoms frequently associated with  large VSDs.
C. Patients with normal pulmonary vascular resistance and left-to-right  shunting across the VSD have Eisenmenger’s complex.
D. Patients with a large VSD and low pulmonary vascular resistance can  present with a mid diastolic murmur at the apex.

26) c

VSD usually closes in early life especially first two years, up to 70% but  then this percentage is lower in later life up to 5 years and the total  percentage would be 25-50%.

Mixing of the blood usually lowers tissue  oxygenation leading to delayed growth, in the same time, increased blood  flow to the lungs will cause pulmonary perfusion affecting gaseous  exchange rate and as a compensation the respiratory rate increases.
Long standing left to right shunt across the VSD Causes more blood to  flow toward the lungs, leading to increased pulmonary vascular resistance  and hence increasing pulmonary artery pressure and right ventricle pressure in return, over time the pressure in the right ventricle will be  higher than that of left ventricle causing the shunt to reverse ( right to left ) which is known as Eisenmenger syndrome.
Mid-diastolic murmur reflects large flow across mitral valve due to over- circulation of the lungs.

Q 27. Which of the following has the greatest impact  on the physiology of tetralogy of Fallot?
A. The size of the ASD.
B. The size of the VSD.
C. The degree of pulmonary stenosis.
D. The amount of aortic overriding

27 c

ASD & VSD will lead to left to right shunting but the most important  factor is RVOT obstruction that will limit the pulmonary blood flow and  protect the lungs from over-circulation.
Right ventricular outflow tract obstruction reduces pulmonary blood  flow and also increases right ventricular pressure leading to right to left  shunt if there is large unrestrictive VSD, both these factors cause cyanosis
and affect the general condition of the patient
The degree of aortic overriding has no affect on blood flow and  physiology

Q28 ) ASD most commonly associated with mitral insufficiency
a) Secundum defect
b) Sinus Venosus defect
c) Ostium primum
d) Coronary sinus defect

28 ) c

ASD secundum is located usually in the depression of the inter-
atrial septum named fossa ovalis, distant from the endocardial
cushion, this cushion is responsible for the formation of the
septal leaflets of mitral and tricuspid valves, and in the same
time give rise to part of the septum primum that complete the
closure of the inter-atrial septum. Thus alteration in the
formation of this part will result in a defect in the lowermost
part of the septum ( ostium primum ) with malformations in
the septal leaflets of mitral or tricuspid valves.
Sinus venosus in embryological life is the common pulmonary
venous drainage to the heart, initially drains to the caudal part
of the right atrium, later on in life the left side incorporates
with coronary sinus, and right side become part of the wall of
the right atrium, and the venous return is directed to the left
atrium alone, if the pulmonary venous return is still connected
to the coronary sinus its coronary sinus type ASD, and if the
merge with right atrium fails and still opened to it then it’s
sinus venosus type ASD

Q29 ) In a Neonate with symptomatic coarctation of aorta, which of the following is acceptable method of repair?

a) Prosthetic patch aortoplasty

b) Resection with end to end anastomosis

c) Subclavian flap aortoplasty

d) Prosthetic tube graft repair

29 ) b

During infancy, the aorta is highly elastic with few collaterals are established to
bypass the coarctation so, the preferable option is to resect the narrowed
segment totally and do an end-end anastomosis. This modality is advantageous
over prosthetic patch aortoplasty and prosthetic tube graft repair is that no
prosthetic material is used thus no need for life long anticoagulant or anti-platelet
agents, and unlike subclavian flap aortoplasty there is no significant alteration to
normal vascular anatomy.

Q 30 ) Which is a true vascular ring?

a) Pulmonary artery sling

b) Double aortic arch

c) Cervical aortic arch

d) Origin of subclavian artery from descending aorta

30 ) b 
Double aortic arch is a true (complete) vascular ring where they encircle and may
constrict the trachea and esophagus. Aberrant origin of Rt. SCA from descending
aorta is a partial vascular ring, cervical aortic arch is an aortic arch anomaly
characterized by elongated, high lying aortic arch and is not a vascular ring.