Left atrial to aortic root indices using two-dimensional and M-mode echocardiography in cavalier King Charles spaniels with and without left atrial enlargement

Vet Radiol Ultrasound. Nov-Dec 2002;43(6):568-75. doi: 10.1111/j.1740-8261.2002.tb01051.x.


Two-dimensional (2-D) echocardiographic measurement of the left atrium (LA) has the potential to be more accurate than the standard M-mode method, because the LA body can be measured. We evaluated a 2-D method for measuring LA and aorta (AO) in a right parasternal short-axis view and compared it to the M-mode method. An index for LA size (LA/AO) was calculated in 166 cavalier King Charles spaniels, 56 normal and 110 dogs with mitral regurgitation (MR) of varying degrees secondary to chronic valvular disease. In normal dogs, the AO-2-D and LA/AO-2-D did not correlate to body weight (BW) or BW2; whereas, all M-mode values and the LA-2-D were significantly (p < .05) related to both BW parameters. In normal dogs, there was no difference between M-mode and 2-D indices. For all dogs (normal and dogs with MR) there was an 11% bias between the M-mode and 2-D index with the LA/AO-2-D being higher than the LA/AO-M. The association between the mean and the difference of the indices demonstrated a quadratic relationship. Dogs with a mean LA/AO of 2.0-2.5 showed the largest difference between the two indices. Small values for the 2-D coefficients of variation for respiration and stage of diastole were found; 3.4 and 3.1%, respectively. The 2-D index is more sensitive to LA enlargement than the M-mode index.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aorta / anatomy & histology
  • Aorta / diagnostic imaging
  • Breeding
  • Case-Control Studies
  • Dog Diseases / diagnostic imaging*
  • Dogs / anatomy & histology*
  • Echocardiography / standards
  • Echocardiography / veterinary*
  • Female
  • Heart Atria / anatomy & histology
  • Heart Atria / diagnostic imaging
  • Male
  • Mitral Valve Insufficiency / diagnostic imaging
  • Mitral Valve Insufficiency / veterinary*
  • Predictive Value of Tests
  • Sensitivity and Specificity