Maternal left ventricular transverse and long-axis systolic function during pregnancy.

Area of Science:

• Cardiology
• Physiology
• Obstetrics

Background:

• Conventional echocardiography of left ventricular systolic function during pregnancy relies on circumferential fiber shortening.
• Existing methods yield conflicting results due to geometric assumptions invalidated by pregnancy-induced left ventricular shape changes.
• Left ventricular long-axis displacement is proposed as a geometry-independent index of systolic function.

Purpose of the Study:

• To compare left ventricular long-axis shortening with circumferential shortening during left ventricular contraction in pregnant women.
• To evaluate the utility of left ventricular long-axis displacement as a systolic function index during pregnancy.

Main Methods:

• A cross-sectional study involving 125 pregnant women (9-42 weeks gestation) and 19 non-pregnant controls.
• Two-dimensional and M-mode echocardiography were used to measure left ventricular long-axis displacement and activation time.
• Activation time was defined as the interval from the ECG Q-wave onset to the start of left ventricular long-axis shortening.

Main Results:

• Mean arterial pressure and activation time decreased during pregnancy, reaching nadirs around 19 weeks, then increased towards term.
• Left ventricular long-axis displacement increased with gestational age, peaking around 23 weeks (+12% vs. non-pregnant), mirroring arterial pressure and activation time trends.
• Ejection fraction and fractional shortening remained stable until late pregnancy (30-32 weeks) before declining.

Conclusions:

• Left ventricular long-axis performance alterations during pregnancy precede changes observed in transverse function measures.
• Left ventricular long-axis displacement offers an earlier and potentially more accurate assessment of systolic function changes during gestation.