Left Apical Four-chamber View Research Articles

Two-dimensional echocardiographic estimates of left ventricular volumes obtained in different views in dogs provide similar measurements but are not interchangeable

IntroductionLittle information exists regarding the interchangeability of left ventricular volume estimates using a monoplane Simpson's Method of Discs on images obtained from the left apical four-chamber and right parasternal long axis four-chamber views. We examined if volume estimates obtained from these views were interchangeable. AnimalsA total of 224 dogs: 86 healthy, 96 with mitral valve disease, 42 with various cardiac pathologies. Materials and methodsInvestigators obtained right parasternal long-axis and left apical four-chamber views from each dog and used manufacturer-supplied software to estimate left ventricular volumes in diastole and systole using Simpson's Method of Discs. Estimates based on linear measurements (diameter cubed, 0.67∗diameter cubed, and Teichholz) were also calculated. Reproducibility for each view, and agreement between the estimates obtained with each view, and those calculated from linear dimensions, were examined using Limits of Agreement. Reference intervals for volumes indexed to bodyweight and body surface area were calculated. ResultsNeither method proved very reproducible. Although no bias was detected, the agreement between volumes indexed to bodyweight and body surface area was insufficient to recommend interchangeability. Estimates based on Teichholz and diameter cubed methods overestimated volumes; however, those based on 0.67∗diameter cubed performed reasonably. ConclusionsMonoplane volume estimates from the left apical and right parasternal long axis four-chamber views are similar but not interchangeable. Clinicians can perform crude estimates of left ventricular volume using the equation 0.67∗diameter cubed.

Tricuspid annular plane systolic excursion in dogs with myxomatous mitral valve disease with and without pulmonary hypertension

ObjectivesTo evaluate tricuspid annular plane systolic excursion (TAPSE) in dogs with myxomatous mitral valve disease (MMVD) with or without pulmonary hypertension (PH) and to study the correlations with clinical and echocardiographic parameters. AnimalsThe study population included 99 dogs with MMVD and tricuspid regurgitation. MethodsThis is a prospective clinical study. All dogs received a transthoracic echocardiographic evaluation, including 2D, M-mode, echo-Doppler, and tissue Doppler measurements. The TAPSE was measured from the left apical four-chamber view and normalized for the effect of body weight (nTAPSE). The dogs were grouped according to the severity of MMVD (American College of Veterinary Internal Medicine guidelines) and presence/absence and severity of PH. Significant differences between TAPSE or nTAPSE and echocardiographic parameters were analyzed among the MMVD and PH severity groups. Correlations between TAPSE or nTAPSE and echocardiographic parameters were calculated. ResultsTricuspid annular plane systolic excursion or nTAPSE were not significantly different among dogs of the MMVD or PH severity groups. Significant correlations were obtained between TAPSE and body weight, left ventricular and atrial dimensions, early diastolic septal and early diastolic and systolic tricuspid annulus velocity (p<0.001); nTAPSE was significantly correlated with normalized end-diastolic left ventricular dimension and fractional shortening (p<0.001). ConclusionsThe results show that neither TAPSE nor nTAPSE are reduced in dogs with MMVD with or without PH. It remains unclear if the right ventricle function is not reduced or if a reduced right ventricle function is masked by the contraction of the left ventricle through ventricular interdependence.

Assessment of right ventricular function by feature-tracking echocardiography in conscious healthy dogs

Advanced two-dimensional echocardiographic techniques allow strain (S) analysis of regional function and thus can provide information on regional myocardial deformation. Feature-tracking echocardiography (FTE) is based on a mono-dimensional technology and may offer more detailed information about septal deformation because it can analyse the activity of left- and right-sided septal fibres separately. The present study aimed to quantify global and regional (free wall and septal) right ventricular (RV) longitudinal S and strain rate (SR). We also investigated the relationships of S and SR with age, sex, weight, breed (sighthound breed vs other breeds), and heart rate. Cine loops were acquired from the left apical four-chamber view, optimized for the RV, in 60 dogs. The within-day and between-day intra-observer coefficient of variation for global RV S and SR in normal dogs using FTE was acceptable (<8.5%). Global longitudinal S (GLS) and SR showed a significant correlation with breed. GLS showed a significant weak positive correlation with weight. Global longitudinal SR showed a significant moderate negative correlation with heart rate. No correlation was found between GLS/SR and age. There was no significant difference between male and female dogs. This study shows, for the first time, that a novel FTE algorithm represents a promising and feasible non-invasive technique to assess RV myocardial function (free wall and septal deformation) in dogs. Based on our results, sighthound breeds appear to need specific reference values.