Question

The M-mode measurements that have been proposed as an indicator for aortic valve replacement in patients with chronic severe aortic insufficiency are left ventricular:

A. End-diastolic dimension ≥ 55 mm and fractional shortening of ≤25%
B. End-diastolic dimension ≤ 55 mm and fractional shortening of ≥ 25%
C. End-diastolic dimension ≥70 mm and left atrial dimension ≥ 55 mm
D. End-systolic dimension ≥ 55 mm and fractional shortening of ≤ 25%

Answer 1

The M-mode measurements indicating aortic valve replacement due to chronic severe aortic insufficiency are A. End-diastolic dimension ≥ 55 mm and fractional shortening of ≤25%. SV and ejection fraction are important cardiac function measurements related to this condition.

Step-by-step explanation:

The M-mode measurements that have been proposed as an indicator for aortic valve replacement in patients with chronic severe aortic insufficiency are left ventricular end-systolic dimension (ESV) and fractional shortening. The correct measurements for considering aortic valve replacement are: A. End-diastolic dimension ≥ 55 mm and fractional shortening of ≤25%. Stroke volume (SV) is normally measured using an echocardiogram to record end diastolic volume (EDV) and ESV, and calculating the difference: SV = EDV - ESV. An average resting heart rate (HR) can vary but is typically 75 bpm, with a normal range for SV being 55-100 mL.

SVs are also used to calculate the ejection fraction, which is expressed as a percentage and ranges from approximately 55-70 percent, with a mean of 58 percent. In the context of aortic insufficiency, the dimensions and functional measurements of the heart are critical in determining the need for surgical intervention, such as valve replacement.