RESUMO
BACKGROUND: Reference intervals for simple body weight-independent measurements of right heart size and function are limited. OBJECTIVES: Generate reference intervals for measurements of right heart size indexed to the long-axis aortic valve diameter (AoD) or corresponding left heart structure (right heart ratios) and describe the reproducibility of these indices. ANIMALS: Ninety healthy adult dogs of variable body weight. METHODS: Prospective study. All dogs underwent an echocardiogram performed by the same operator. Numerous linear 2-dimensional measurements of right heart size and function from different imaging planes were performed. Eight dogs underwent repeated echocardiograms by the same operator on 3 different days, and 3 different operators performed repeated echocardiograms on the same day. Reference intervals were generated using the Clinical Laboratory Standards Institute method. Reproducibility was quantitated using coefficients of variation (CVs) and reproducibility coefficients. RESULTS: Reference intervals for right heart ratios were generated and allow simple assessments of right heart size and function that do not require a scaling exponent or body weight table. Right heart ratios did not show clinically relevant associations with body weight. All CVs were <22.6%. In general, CVs for right heart measurements indexed to AoD were lower compared with right heart measurements indexed to the corresponding left heart structure. CONCLUSIONS AND CLINICAL IMPORTANCE: Reference intervals for simple body weight-independent right heart ratios are available to help detect abnormalities of right heart size and function. Reproducibility coefficients might be useful to help identify meaningful changes in right heart size during serial evaluations.
RESUMO
BACKGROUND: Differentiating cardiogenic vs noncardiogenic causes of respiratory signs can be challenging when echocardiography is unavailable. Radiographic vertebral left atrial size (VLAS) and vertebral heart size (VHS) have been shown to predict echocardiographic left heart size, with VLAS specifically estimating left atrial size. HYPOTHESIS/OBJECTIVES: Compare the diagnostic accuracy of VLAS and VHS to predict left-sided congestive heart failure (CHF) in dogs presenting with respiratory signs. ANIMALS: One-hundred fourteen dogs with respiratory signs and radiographic pulmonary abnormalities. METHODS: Retrospective cross-sectional study. Dogs had to have an echocardiogram and thoracic radiographs obtained within 24 hours. Diagnosis of CHF was confirmed based on the presence of respiratory signs, cardiac disease, LA enlargement, and cardiogenic pulmonary edema. RESULTS: Fifty-seven dogs had CHF and 57 did not have CHF. Compared to VHS (area under the curve [AUC] 0.85; 95% confidence interval [CI], 0.77-0.91), VLAS was a significantly (P = .03) more accurate predictor of CHF (AUC, 0.92; 95% CI, 0.85-0.96). Optimal cutoff for VLAS was >2.3 vertebrae (sensitivity, 93.0%; specificity, 82.5%). Murmur grade (P = .02) and VLAS (P < .0001) were independently associated with CHF and VHS was not. Increased VHS (54%) was significantly (P = .01) more common than increased VLAS (24%) in dogs without CHF. Results were similar in a subsample of older and smaller dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: When echocardiography is unavailable, VLAS and murmur grade have clinically utility to aid in differentiating cardiogenic from noncardiogenic respiratory signs. These findings might be especially useful to help rule out CHF in dogs with increased VHS that present with respiratory signs.