Final answer:
After MR and AR valve repair, the ejection fraction often improves due to changes in afterload and EDV. The repair aims to reduce regurgitant volume and decrease the stress on the heart, which can lead to better heart function and normalized EF values.
Step-by-step explanation:
The pathophysiology behind the changes in ejection fraction (EF) after mitral regurgitation (MR) and aortic regurgitation (AR) valve repair concerns the relationship between stroke volume (SV), end-diastolic volume (EDV), and end-systolic volume (ESV). SV is influenced by preload, contractility, and afterload. In the case of valve repair, particularly for MR and AR, there is a change in the afterload and ventricular volumes which affect SV and subsequently EF. EF is the portion of blood ejected from the heart with each contraction, calculated as SV divided by EDV, and expressed as a percentage. Valve repair generally aims to normalize these values, thus normalizing EF.
After MR or AR valve repair, there is typically a reduction in the regurgitant volume leading to a decrease in EDV. As a result, there is less stress on the heart muscle, potentially leading to improvements in EF. However, the actual change in EF will depend on the individual patient's condition and the effectiveness of the repair. The key factor is that afterload decreases as the resistance against which the heart must pump is reduced, typically leading to an improved EF following successful valve repair.