Assessing the repeatability, reliability, and precision of right ventricular outflow tract and mid-pulmonary artery diameters, velocity time integrals, and agreement between site-specific stroke volumes.

Background: Right ventricular (RV) stroke volume (SV) can be calculated via Doppler echocardiography at multiple sites in the right chambers. However, the agreement between the calculated SVs at these sites is unknown. We aimed to assess the repeatability, reliability, and precision of the distal right ventricular outflow tract diameter (RVOTD), the mid-pulmonary artery diameter (MPAD), the right ventricular outflow tract velocity time integral (VTI), and the mid-pulmonary artery velocity time integral (MPAVTI). Additionally, we evaluated the agreement between RVOTSV and MPASV.

Methods: Four observers each evaluated approximately 100 patients (n = 406). Basic measurements were made over three cardiac cycles, and the repeatability, reliability, and precision of the measurements were calculated. The agreement between the two methods was presented as intraclass correlation coefficients.

Results: The repeatability coefficient ranges for RVOTD, MPAD, RVOTVTI, and MPAVTI were 2-3 mm, 2-4 mm, 2.1-2.8 cm, and 2.4-4.1 cm, respectively. The minimal detectable change ranges for these variables were 2-4 mm, 2-5 mm, 2.2-3.0 cm, and 2.6-4.3 cm, respectively. The respective precision ranges for RVOTD, MPAD, RVOTVTI, and MPAVTI were 2.7-4.7%, 2.4-5.4%, 5.0-7.4%, and 5.4-9.2%. There were significant correlations and agreements between MPASV and RVOTSV, with the Pearson correlation coefficient ranging from 0.63 to 0.89 (P < 0.001). The intraclass correlation coefficient ranged from 0.56 to 0.89 (P < 0.001), although there was a significant bias of 1.9-11.3 mL (P < 0.001).

Conclusions: The RVOTD, MPAD, RVOTVTI, and MPAVTI measurements were repeatable, reliable, and precise. The agreement between RVOTSV and MPASV ranged from fair to excellent, although significant bias, along with a wide limit of agreement, was observed. Consequently, these methods cannot be used interchangeably.