Question

Hans Dietz is a 25 year old male patient with a family history of Marfan Syndrome (MFS). He is generally well and enjoys attending regular fitness sessions in his local gymnasium. During a recent gym session, he experienced dizziness followed by a fainting episode. He presented at the emergency department and a new systolic murmur was heard. Mr Dietz subsequently underwent screening for cardiovascular abnormalities associated with his family history of Marfan Syndrome.

Question 1

The fibrous structure of the heart is comprised predominantly of connective tissue proteins.

Describe the microscopic composition of the layers of the mitral valve. Your answer must include a description of the connective tissue element, the cell types found in each layer and how the layers are arranged (i.e. their structure or architecture). (3 marks)            

Question 2

Upon further evaluation with an echocardiogram (cardiac ultrasound), Mr Dietz was found to have an enlarged (dilated) proximal ascending aorta, mitral valve prolapse with myxomatous changes and elongated chordae.

The patient was noted as having myxomatous changes in the mitral valve leaflets and associated elongation of the chordae tendineae. Explain what is meant by the term myxomatous changes. Your answer must include a description of the cellular and structural changes that occur within the valve. (2 marks)

Question 3

Where on the body would be the ideal position for the clinician to auscultate for a systolic murmur associated with the mitral valve? (2 marks)

Question 4

Describe the secondary complications (or consequences) that will occur as a result of the changes in the structure of the mitral valve in a patient with Marfan syndrome. Your answer should link to the clinical sign of the new systolic murmur noted in this patient. (3 marks)

Answer 1

Question 1) The layers of mitral valve -

1) Atrialis - uppermost layer adjacent to left atrium composed of elastic and collagen fibres covered with overlying endothelium.

2) spongiosa - It is found beneath Atrialis extracellular matrix formed of ground substance and elastic fibres.

3) Fibrosa - beneath sponsgiosa it is load-bearing layer . It comprises the central structural collagenous layer .This layer provides strength.

4)ventricularis- covered by continuous sheet of endothelial cells that overlie elastic fibres and collagen fibres.

Question 2) Myxomatous change in mitral valve is non-inflmmatory progressive disarrangement of valve due to defect in mechanical integrity of leaflet due to altered synthesis and remodeling by type 4 collagen.

Question 3 ) The lateral decubitus position is best for murmur detection associated with mitral valve.

question 4) Secondary changes due to structural change in mitral valve- mitral valve prolapse due to marfan syndrome and others are sudden heart attack and arrythmia.