The objective of the study is to evaluate if there is a correlation between EDVI, ESVI, LA/AO and transmitral flow patterns with the different ISACHC classes in mitral insufficiency patients.
The case records of 704 dogs diagnosed with mitral insufficiency examined during a 3-year period, were reviewed retrospectively. Mitral insufficiency patients were divided in four groups based on the ISACHC (International Small Animal Cardiac Heart Council) classification: ISACHC Ia, ISACHC Ib, ISACHC II and ISACHC IIIa. EDVI (end diastolic volume index), ESVI (end systolic volume index), LA/AO (left atrium/aorta) ratio were calculated for each group. Transmitral flow pattern was divided in: normal pattern, impaired relaxation pattern, pseudornomal and restrictive pattern. EDVI and ESVI were calculated using the M-mode from the short axis right parasternal view at the level of the cordae tendineae insertion of the left ventricle. LA /AO ratio was obtained from the right parasternal short axis view al the level of the aortic valve trying to get the maximum dimensions of LA. Transmitral flow patterns were obtained from the apical left parasternal four chamber view with the volume sample just on the tips of the open mitral valve leaflets. All patients were evaluated by the same echocardiographer and all the echocardiographic examinations were performed with the same protocol order. No sedation was performed in any patients.
The ESVI, EDVI and LA/AO ratio mean values for patients in class ISACHC Ia were: 28.1, 91.1, 1.4 ; for patients in class ISACHC Ib: 34.3, 110.6, 1.7 ; for patients in class ISACHC II: 41.2 , 143 , 2.1 ; for patients in Class IIIa: 54.4 , 197.8 , 2.7 respectively . The mean values of the LA/AO ratio in patients with impaired relaxation pattern was 1.6, in pseudonormal pattern was 2.1 and in restrictive pattern was 2.4. The mean values of the EDVI in patients with impaired relaxation pattern, pseudonormal pattern and restrictive pattern were 105.2 , 149.5 , 196.3 respectively.
ESVI, EDVI and LA/AO ratio values increases directly with ISACHC classification in mitral insufficiency patients. Diastolic mitral inflow patterns changes with the progression of the disease from impaired relaxation to restrictive patterns and is directly correlated with the increases on the EDVI and LA/AO ratio values. Transmitral flow patterns can be modified by many factors (respiration, arrhythmias...), and is the most variable of the echocardiographic parameters we already described. ESVI, EDVI, LA/AO ratio and diastolic transmitral flow patterns are useful echocardiographic indicators for mitral insufficiency stadiation and can be used as a prognostic and therapeutic indicators. ESVI, EDVI and LA/AO ratio are less variable indicators than transmitral flow and should be done in all mitral insufficiency patients in order to do a more precise and objective stadiation of the mitral disease besides the clinical ISACHC classification.