Simpson's Method of Discs for Measurement of Echocardiographic End‐Diastolic and End‐Systolic Left Ventricular Volumes: Breed‐Specific Reference Ranges in Boxer Dogs

Abstract

BackgroundBoxer dogs are predisposed to congenital and adult onset cardiac diseases. Breed‐specific reference values for M‐mode and Doppler echocardiographic measurements previously have been established. Left ventricular (LV) end‐systolic (ESV) and end‐diastolic volumes (EDV) can be measured by M‐mode or two‐dimensional methods, such as Simpson's method of discs (SMOD). Reference ranges for SMOD‐derived LV volumes are lacking.ObjectivesTo determine reference intervals for EDV and ESV in Boxer dogs.AnimalsPreviously collected data from 85 healthy Boxers (37 males and 48 females) were used for analysis.MethodsSimpson's method of discs‐derived EDV and ESV were measured using offline analysis by 1 observer, in both the right parasternal and the left apical views. Measurements were compared between both views and between male and female dogs using a t‐test. Reference intervals were established using the mean + 2 × SD.ResultsMeasurements obtained from both views showed good agreement, and mean EDVI and ESVI, indexed to body surface area (BSA), were calculated. Reference intervals were 49–93 mL/m² for EDVI, and 22–50 mL/m² for ESVI. EDV and ESV were significantly higher in males compared with females, when indexing to BSA, but not when indexing to body weight.Conclusion and Clinical ImportanceThe upper limit for ESVI exceeds the previously suggested cut‐off of 30 mL/m² for detection of systolic dysfunction. The reference intervals generated in this study should be useful clinically in the assessment of LV size and function in Boxer dogs.

Breed‐specific reference ranges for standard echocardiographic measurements in salukis

“…In order to compare our results with previous studies with other breeds, we indexed the LV volumes also to body surface area. Our results for LV end-diastolic and end-systolic volume indexes (EDVI <128.5 mL/m 2 and ESVI <70.2 mL/m 2 ) were similar to those of previous study on sighthounds, but larger than those described in other large breeds with EDVI ranging from <80 to 126 mL/m 2 and ESVI from <47 mL/m 2 to <64 mL/ m 2 (Wess et al 2010, Smets et al 2014, Seckerdieck et al 2015, Dickson et al 2016.…”

“…With dogs, a normal range for Simpson's EF is still largely based on human studies, and EF >40 to 44% has been considered normal (Dukes-McEwan et al 2003, Wess et al 2010, Stephenson et al 2012, McKaigney et al 2014, Seckerdieck et al 2015. Based on our study, salukis appear to have a similar lower reference limit for EF compared with some other breeds (Smets et al 2014, Dickson et al 2016.…”

“…Based on our study, salukis appear to have a similar lower reference limit for EF compared with some other breeds (Smets et al . , Dickson et al . ).…”

Echocardiography

“…The literature contains a number of publications about echocardiographic measurement of normal and abnormal heart size in dogs, 34,44,96,105,107,108,111,135,138,[231][232][233][234][235][236][237][238][239][240][241][242][243][244][245][246] while a smaller number address the subject in cats. 31,75,99,101,107,177,242,[247][248][249][250] Most canine studies report either breed-specific values or combine different breeds and emphasize the importance of body size on chamber measurements, modeling this influence into normal reference values.…”

“…When dyssynchrony is evident, LV wall amplitude is often normal and this finding suggests LV systolic function is not impaired. 245 Perhaps 3D methods with MRI validation will address this issue more definitively. 108,121,122 The use of M-mode derived calculation of LV end-systolic volume, indexed to body size, has been proposed as a method of identifying LV systolic dysfunction in dogs.…”