W3. Cardiac

Question 1

Etiology and Pathogenesis of congenital heart disease

Answer 1

• cause and pathogenesis of most congenital heart defects are not known
• either endogenous (chromosomal abnormalities ex. downs)
• or exogenous (alcohol during pregnancy)
• Heart is completely formed and functioning at 10th week of pregnancy

Question 2

During development, if left side of the heart is not completely separated from the right

Answer 2

Atrial septal defects or ventricular septal defects occur

Question 3

If twisting of the heart and its subdivision into 4 chabers occurs during development….

Answer 3

Tetralogy of fallot

Question 4

Atrial Septal Defect

(Most common, recognised clinically, consequences, can be fixed?)

Answer 4

• most common results from incomplete or defective closure of the foramen ovale (a fetal septal opening between the left and right atrium, that typically closes in the first few days after birth)
• recognised clinically by the murmor caused from passage of blood from left to right atrium during systole
• minor functional consequences until it becomes prominent, or complicated by endocardial infection
• may serve as conduit for venothromboemoli
• can be easily closed via surgical intervention

Question 5

Ventricular Septal Defect

Pathogenesis

Answer 5

• Most common congenital heart defect in clinical practice
• Symptoms are from mixing of blood in left and right chambers
• because pressure from the left chamber exceeds pressure from the right, the artial blood from the left ventricle or atrium will flow to the right side of the heart=left to right shunt

As a result of this backflow of blood, this causes the right ventricle to work harder, thus right ventricular hypertrophy

Increased flow of blood to pulmonary arteries results in pulmonary HTN

Pulmonary HTN and pulmonary artery narrowing reaches a point where pressure in right ventricle exceeds pressure in the left ventricle

This reverses blood flow and causes right to left shunt= unoxygenated venous blood from right atrium and ventricle enters circulation = cyanosis

Question 6

Ventricular Septal Defect:

clinical signs

Answer 6

• High pitched systolic murmor, but most have no symptoms
• can close spontaneously
• larger defects need surgery