The preferable position for quantifying left ventricular diameter by transthoracic echocardiography.

BACKGROUND

In quantifying left ventricular (LV) diameter, which position for echocardiographic measurements, mitral valve tip level (MV-tip) or LV mid level (LV-mid), more accurately represents the LV volume is unclear. Furthermore, which factor affects the measurement error also has not been elucidated.

METHODS

We enrolled 150 patients without myocardial infarction and local asynergy who underwent echocardiography and cardiac magnetic resonance imaging (CMRI). Echocardiographic LV diastolic diameter (LVDD) and LV systolic diameter (LVDS) were measured at both MV-tip and LV-mid, and the LV end-diastolic volume (LVEDV) and end-systolic volume (LVESV) were quantified using CMRI. We quantified the degree of aortic wedging as the angle between the anterior wall of the aorta and the ventricular septal surface (ASA).

RESULTS

The average LVDD was smaller and average LVDS larger when measured at the MV-tip than at the LV-mid. In regression analyses, the correlation coefficient between LVDD and LVEDV was larger at LV-mid (R = 0.89) than at MV-tip (R = 0.82), and the correlation coefficient between LVDS and LVESV also larger at LV-mid (R = 0.93) than MV-tip (R = 0.87). ASA, Valsalva diameter, left atrial diameter, patient height, and LV mass significantly affected the echocardiographic measurement error, but no factor affected the measurement error when quantifying LVDD at the LV-mid level.

CONCLUSIONS

The echocardiographic LV diameter measured at LV-mid has a stronger correlation with LV chamber size derived from CMRI than measurements at MV-tip. The LVDD measured at the LV-mid level is not affected by other factors.