MCQ: Cardiovascular System Pathology – 27 MCQs | Kenya MBChB

27 Year 3: Cardiovascular System Pathology exam questions on MCQ: Cardiovascular System Pathology for medical students. Includes MCQs, answers, explanations and

This MCQ set contains 27 questions on MCQ: Cardiovascular System Pathology in the Year 3: Cardiovascular System Pathology unit. Each question includes the correct answer and a detailed explanation for active recall and exam preparation.

Q1: Which foramen ovale closes in approximately 75% of individuals at birth?

  1. A. Ostium primum
  2. B. Ostium secundum
  3. C. Foramen ovale
  4. D. Fossa ovalis

Correct answer: C – Foramen ovale

Closes by fusion of septum primum and secundum. Persists in 25% of adults as PFO.

Q2: Anatomical closure of the ductus arteriosus occurs through which process?

  1. A. Smooth muscle hypertrophy
  2. B. Thrombosis and calcification
  3. C. Intimal proliferation and fibrosis
  4. D. Inflammatory cell infiltration

Correct answer: C – Intimal proliferation and fibrosis

Functional closure via vasoconstriction occurs first. Anatomical closure takes several weeks through intimal proliferation and fibrosis.

Q3: Failure of which structure to adequately cover the ostium secundum results in ostium secundum ASD?

  1. A. Septum primum
  2. B. Endocardial cushion
  3. C. Septum secundum
  4. D. Sinus venosus wall

Correct answer: C – Septum secundum

Ostium secundum ASD occurs when the septum secundum does not enlarge sufficiently to cover the ostium secundum.

Q4: Which VSD type is specifically more common in Asian patients?

  1. A. Muscular trabecular VSD
  2. B. Membranous VSD
  3. C. Inlet VSD
  4. D. Doubly committed subarterial VSD

Correct answer: D – Doubly committed subarterial VSD

Situated in the outlet septum, bordered by fibrous continuity of aortic and pulmonary valves.

Q5: The fundamental embryological defect in Tetralogy of Fallot is:

  1. A. Failure of truncus arteriosus to divide
  2. B. Anterior cephalad deviation of the outlet septum
  3. C. Apical displacement of the tricuspid valve
  4. D. Failure of endocardial cushions to fuse

Correct answer: B – Anterior cephalad deviation of the outlet septum

This single defect produces all four features of TOF — outlet VSD, pulmonary outflow obstruction, overriding aorta and RVH.

Q6: Which structure, when displaced apically, causes atrialization of the right ventricular inflow tract?

  1. A. Anterior mitral valve leaflet
  2. B. Septal leaflet of tricuspid valve
  3. C. Posterior leaflet of tricuspid valve
  4. D. Septal leaflet of mitral valve

Correct answer: B – Septal leaflet of tricuspid valve

This is Ebstein's anomaly. Apical displacement of the septal tricuspid leaflet causes the RV inflow to function as an atrial chamber.

Q7: In Transposition of Great Arteries, which embryological failure is directly responsible?

  1. A. Failure of truncus arteriosus to partition
  2. B. Failure of subaortic conus to elongate
  3. C. Resorption of subpulmonary instead of subaortic conus
  4. D. Malalignment of the outlet septum anteriorly

Correct answer: C – Resorption of subpulmonary instead of subaortic conus

Normally the subaortic conus resorbs, moving the aorta posteriorly to connect with the LV. In TGA the wrong conus resorbs, keeping the aorta anterior and connected to the RV.

Q8: Which chromosomal abnormality is most specifically associated with coarctation of the aorta?

  1. A. Trisomy 21
  2. B. Trisomy 18
  3. C. Turner syndrome
  4. D. Trisomy 13

Correct answer: C – Turner syndrome

Turner syndrome is specifically associated with coarctation of aorta and bicuspid aortic valve. Trisomy 21 is associated with AV canal defects.

Q9: Persistent truncus arteriosus always occurs alongside which other defect?

  1. A. Atrial septal defect
  2. B. Patent ductus arteriosus
  3. C. Ventricular septal defect
  4. D. Pulmonary valve stenosis

Correct answer: C – Ventricular septal defect

The single great vessel overrides both ventricles, so a VSD is always present in persistent truncus arteriosus.

Q10: Sinus venosus ASD is specifically associated with anomalous drainage of pulmonary veins from which lung?

  1. A. Left upper lobe
  2. B. Left lower lobe
  3. C. Right lung
  4. D. Both lungs equally

Correct answer: C – Right lung

Right pulmonary veins drain anomalously into the SVC or right atrium due to the proximity of the sinus venosus defect to the SVC entry.

Q11: Which maternal teratogen is specifically associated with Ebstein's anomaly?

  1. A. Isotretinoin
  2. B. Thalidomide
  3. C. Warfarin
  4. D. Lithium

Correct answer: D – Lithium

Maternal lithium use in first trimester is the specific teratogen classically associated with Ebstein's anomaly.

Q12: A restrictive VSD differs from a non-restrictive VSD in that it:

  1. A. Always requires surgical correction
  2. B. Causes immediate pulmonary hypertension
  3. C. May close spontaneously during childhood
  4. D. Always progresses to Eisenmenger syndrome

Correct answer: C – May close spontaneously during childhood

Restrictive VSDs cause no significant haemodynamic derangement and may close spontaneously, unlike large non-restrictive VSDs which cause progressive pulmonary hypertension.

Q13: Which congenital defect results from failure of both subpulmonary AND subaortic conus to resorb?

  1. A. Persistent truncus arteriosus
  2. B. Transposition of great arteries
  3. C. Double outlet right ventricle
  4. D. Tetralogy of Fallot

Correct answer: C – Double outlet right ventricle

Failure of either conus to resorb produces double outlet anomalies of the RV. TGA results from resorption of the wrong conus. TOF results from malalignment, not failure of resorption.

Q14: The ostium primum is created during atrial septation by growth of which structure toward the AV canal?

  1. A. Septum secundum from the right
  2. B. Endocardial cushion from below
  3. C. Septum primum downward from the roof
  4. D. Sinus venosus from the posterior wall

Correct answer: C – Septum primum downward from the roof

The septum primum grows downward creating the ostium primum inferiorly. As it grows, perforations form superiorly creating the ostium secundum.

Q15: VSD accounts for what percentage of all congenital heart disease?

  1. A. 10%
  2. B. 15%
  3. C. 20%
  4. D. 25%

Correct answer: D – 25%

VSD is the most common congenital heart defect overall, accounting for 25% of all CHD.

Q16: Which component of the ventricular septum lies directly beneath the aortic valve?

  1. A. Inlet septum
  2. B. Trabecular septum
  3. C. Membranous septum
  4. D. Outlet septum

Correct answer: C – Membranous septum

The small membranous septum lies just underneath the aortic valve. Membranous VSDs often have inlet, outlet or trabecular extension.

Q17: In which CHD does the right ventricle inflow tract function haemodynamically as an atrial chamber?

  1. A. Tricuspid atresia
  2. B. Ebstein's anomaly
  3. C. Pulmonary atresia
  4. D. Transposition of great arteries

Correct answer: B – Ebstein's anomaly

Apical displacement of the septal tricuspid leaflet causes atrialization of the RV inflow tract — it receives atrial pressure and contracts out of synchrony with the functional RV.

Q18: Which of the following is the correct sequence of atrial septal development?

  1. A. Septum secundum → ostium primum → ostium secundum → fossa ovalis
  2. B. Ostium primum → ostium secundum → septum secundum → fossa ovalis
  3. C. Fossa ovalis → septum primum → ostium primum → septum secundum
  4. D. Septum primum → ostium primum → ostium secundum → septum secundum

Correct answer: D – Septum primum → ostium primum → ostium secundum → septum secundum

Septum primum grows down creating ostium primum. Perforations coalesce into ostium secundum. Then septum secundum develops to the right, leaving the fossa ovalis.

Q19: Which of the following maternal infections is a recognised cause of congenital heart disease?

  1. A. Cytomegalovirus
  2. B. Rubella
  3. C. Herpes simplex virus
  4. D. Toxoplasma gondii

Correct answer: B – Rubella

Maternal rubella is a recognised environmental cause of CHD, particularly PDA and pulmonary stenosis. It is specifically listed among the environmental teratogenic causes of CHD.

Q20: In Tetralogy of Fallot, which level is the dominant site of right ventricular outflow obstruction?

  1. A. Valvular
  2. B. Supravalvular
  3. C. Subvalvular (infundibular)
  4. D. At the pulmonary bifurcation

Correct answer: C – Subvalvular (infundibular)

The dominant obstruction in TOF is at the subvalvular/infundibular level due to hypertrophied infundibular myocardium from the malaligned outlet septum — not at the valve itself.

Q21: Coarctation of the aorta occurs most commonly at which location?

  1. A. Ascending aorta
  2. B. Aortic arch
  3. C. Juxtaductal — at the ductus arteriosus insertion
  4. D. Descending thoracic aorta

Correct answer: C – Juxtaductal — at the ductus arteriosus insertion

Narrowing occurs just distal to the left subclavian artery at the site of ductus arteriosus insertion.

Q22: Which radiological finding is specifically associated with coarctation of the aorta?

  1. A. Boot-shaped heart
  2. B. Egg-on-side appearance
  3. C. Rib notching
  4. D. Enlarged pulmonary trunk

Correct answer: C – Rib notching

Caused by dilated intercostal collateral vessels eroding the inferior rib margins, developing to bypass the coarctation.

Q23: A patient with an untreated large VSD develops reversed cyanosis. Which term describes this end-stage complication?

  1. A. Tetralogy of Fallot
  2. B. Eisenmenger syndrome
  3. C. Truncus arteriosus
  4. D. Ebstein's anomaly

Correct answer: B – Eisenmenger syndrome

Chronic L→R shunting → pulmonary hypertension → pulmonary pressure exceeds systemic → shunt reverses to R→L → cyanosis. This is irreversible.

Q24: Patent foramen ovale in adults is specifically associated with which cerebrovascular complication?

  1. A. Cerebral venous thrombosis
  2. B. Hypertensive hemorrhage
  3. C. Paradoxical embolism causing cryptogenic stroke
  4. D. Cerebral arteriovenous malformation

Correct answer: C – Paradoxical embolism causing cryptogenic stroke

Venous thrombus crosses from right to left atrium through the PFO entering systemic circulation, causing stroke without an obvious arterial source.

Q25: Ostium primum ASD is associated with a cleft in which specific valve leaflet?

  1. A. Posterior mitral valve leaflet
  2. B. Anterior mitral valve leaflet
  3. C. Septal tricuspid valve leaflet
  4. D. Anterior tricuspid valve leaflet

Correct answer: B – Anterior mitral valve leaflet

Both the ostium primum ASD and the cleft mitral leaflet result from the same endocardial cushion maldevelopment. Commonly seen in Down syndrome.

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