Journal of Veterinary Cardiology (2013) 15, 253e261
www.elsevier.com/locate/jvc
Echocardiographic measurement of cardiac valvular thickness in healthy cows, cows with bacterial endocarditis, and cows with cardiorespiratory diseases ´bastien Buczinski, Dr Ve ´t, MSc a,*, Mohammad Tolouei, DVM, PhD b, Se Ali Rezakhani, DVM, PhD c, Mohamed Tharwat, DVM, PhD d a
Clinique Ambulatoire Bovine, De´partement des sciences cliniques, Faculte´ de Me´decine Ve´te´rinaire, Universite´ de Montre´al, Que´bec, Canada b Department of Clinical Science, University of Tabriz, Iran c Department of Clinical Studies, School of Veterinary Medicine, Shiraz University, Shiraz, Iran d Department of Animal Medicine, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt Received 18 February 2012; received in revised form 4 June 2013; accepted 1 August 2013
KEYWORDS Heart disease; Valvular; Endocardium; Echocardiography
Abstract Objective: To determine valvular thickness in healthy cows, cows with bacterial endocarditis, and cows with various cardiorespiratory diseases. Animals: 40 healthy Holstein adult cows (CONTROL), 6 adult cows with confirmed bacterial endocarditis (BE), and 10 cows with other cardiorespiratory disorders (NONBE). Methods: Prospective study using right transthoracic echocardiographic examination in CONTROL, BE and NONBE cows. The valvular thicknesses of all cows were assessed in four different locations for all cardiac valves, and the maximal value was used for further analysis. Results: The mean [standard deviation (SD)] maximal thicknesses of the tricuspid, mitral, aortic, and pulmonary valves in the CONTROL group were 0.69 0.10 cm, 0.85 0.21 cm, 0.72 0.17 cm, and 0.58 0.12 cm, respectively. The maximal valvular thicknesses were less than 0.97 cm for the tricuspid, less than 0.91 cm for pulmonary, less than 1.05 cm for the aortic, and less than 1.28 cm for the mitral. In BE cows, the maximal valvular thickness of affected valves (median: 4.22 cm; range: 2.52e6.97 cm) and non affected valves (median: 0.75 cm; range: 0.45e1.52 cm) were significantly different (P ¼ 0.0004). The maximal valvular
* Corresponding author. E-mail address: [email protected] (S. Buczinski). 1760-2734/$ - see front matter ª 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jvc.2013.08.001
254
S. Buczinski et al. thicknesses of the NONBE valves as well as the unaffected valves in the BE group were not significantly different compared to the CONTROL group valves. Conclusions: Using the mean 2SD formula for each valve in healthy cows, a thickness of tricuspid, mitral, aortic or pulmonary valves greater than 0.85 cm, 1.27 cm, 1.06 cm or 0.82 cm respectively should raise the suspicion of valvular bacterial endocarditis. ª 2013 Elsevier B.V. All rights reserved.
Abbreviations BE cTnI SD TEE TTE
bacterial endocarditis cardiac troponin I standard deviation transesophageal echocardiography transthoracic echocardiography
Introduction Although bovine heart diseases are not highly prevalent, their clinical impact is important because the majority of these diseases have poor prognoses.1,2 Bacterial endocarditis (BE) is the most frequent valvular disease in cattle.3e5 The diagnosis of BE may be difficult due to the absence of specific clinical findings in many cases. The most common clinical sign is persistent tachycardia alongside evidence of a chronic inflammatory process on routine bloodwork.1,3,6 Heart murmurs are not always detected in cases of BE and may lack specificity.7 The presence of heart failure is uncommon in cases of BE.1e4,6,8 Because of these challenges, ancillary tests are required to make a definitive diagnosis. In other species, echocardiography is the gold standard test used for antemortem diagnosis.9,10 Transthoracic echocardiography (TTE) allows for an assessment of the consequences of valvular regurgitation, specifically cardiac dilation.9,10 The major echocardiographic findings in cases of BE classically include irregular valvular thickening with various degrees of valvular regurgitation and secondary cardiac chamber enlargement.3,11,12 Due to the fairly low sensitivity and specificity of echo findings, a classification system based upon the presence of clinical findings and results of ancillary tests has been proposed in human cardiology. This classification scheme is known as the Duke criteria13 and it is based on the presence of two levels of diagnostic criteria, the major and minor criteria. Echocardiographic findings with evidence of endocardial involvement (such as oscillating structures, abscesses or new valve
dehiscence) are considered to be major criteria in the antemortem diagnosis of BE in humans.13 To our knowledge, these criteria have not been tested or validated for bovine cases of BE. However, “typical echocardiographic” findings are commonly used in the antemortem diagnosis of bovine BE. These include different subjective findings such as valvular thickening or vegetation, valvular irregularity and/or heterogeneous appearance.2e4,8,11,12 In cattle, a recent randomeffect meta-analysis of published studies in which BE was confirmed using necropsy as the gold standard revealed that TTE had a pooled sensitivity of 84.3% (95% confidence interval: 60.4e95.0%) for BE diagnosis.14 Most of the echocardiographic examinations in published cases, however, have been performed by people with extensive experience of bovine echocardiography in hospital settings. The echocardiographic findings in bovine BE consist of various types of valvular thickening. This definition is quite subjective, especially for noncardiology board-certified veterinarians. Bovine ultrasonography is generally performed by nonspecialists, especially in farm settings, and for this reason it is important to have more objective data to define the normal thickness of cardiac valves in healthy cattle vs. cattle with BE when performing TTE. Therefore, the first aim of this study was to determine the maximal valvular thickness of the mitral, tricuspid, pulmonic, and aortic valves in healthy cows. The second objective of this study was to compare those measurements with a group of cattle with confirmed or presumed BE, or other cardiorespiratory diseases, thereby defining what should be considered valvular thickening.
Animals, materials and methods The study protocol was accepted by the ethical committee of the Faculte ´ de Me ´decine Ve ´te ´rinaire ´thique et d’Utilisation des Animaux). (Comite ´ d’E Forty adult Holstein cows, determined to be free of endocardial disease after a thorough physical examination, cardiac auscultation, and echocardiogram, were used for the determination of
Bovine valvular thickness measurement normal valvular thickness. Holstein cows from 0 to 60 days in milk were randomly selected from four tie-stall dairy farms in the area of the bovine ambulatory clinic, St-Hyacinthe, Que ´bec, Canada. They were initially selected on the basis of the absence of any disease during early lactation, and the fact that they had not received medications in the prior 14 days. The cows were then examined, paying special attention to the cardiovascular system. Cows were excluded if they showed clinical signs of illness, including fever, anorexia, decreased milk production, mastitis, or lameness. A blood sample from each cow was collected from a coccygeal vessel into a heparin-lithium tube, and cardiac troponin I (cTnI) levels were immediately assessed using a handheld analyzer.e
Echocardiography Echocardiography in the CONTROL group A standard echocardiographic examination was performed using a 3.2-MHz phased array probe,f as previously described in standing cows using a right parasternal approach.15e17 The valvular thickness measurements were always performed when the valves were closed during ventricular systole for atrioventricular valves and during ventricular diastole for semilunar valves. Particular attention was paid to the quality of the image recorded, and to measuring the closed valves when the image quality was optimal using the cine-loop mode of the ultrasound. The mitral and tricuspid valve thicknesses were measured using the long-axis four-chamber view during systole (Fig. 1A); both the septal and free-wall leaflets were measured. The aortic valve thickness was measured using the right long-axis view of the left ventricular outflow tract during diastole (Fig. 1B); both the left and right coronary cusps were measured. The pulmonic valve thickness was measured using the right long-axis view of the right ventricular outflow tract during diastole (Fig. 1C); both the anterior and right cusps were measured. Four measurements were obtained for each valve. Two measurements (M1 and M4) were taken at the attachment of the valve to the mural endocardium, with special attention to avoid valvular chordae in the measurement (Fig. 2). Two measurements (M2 and M3) were taken at the free extremity of the valve. The maximal valvular thicknesses were determined for each cardiac e f
I-Stat 1, Abaxis, Union City, CA, USA. Logiqbook, General Electric, Wawatosa, WI, USA.
255 valve. The mean maximal valvular thicknesses of the pulmonary, aortic, tricuspid and mitral valves were then determined.
Echocardiography in the BE group Between January 2007 and July 2012, every cow presented to the bovine ambulatory clinic of the Faculte ´ de Me ´decine Ve ´te ´rinaire, St-Hyacinthe, suspected of having cardiac disease underwent a complete right parasternal echocardiographic examination by the same operator (SB) with the same ultrasound unit.f Every echocardiographic examination was stored for further analysis. Echocardiograms of 12 client-owned adult Holstein cows with a diagnosis of valvular BE were reviewed by the same operator (SB). All cows underwent standard right transthoracic echocardiography15e17 during which particular attention was paid to the visualization of both semilunar and atrioventricular valves. The diagnosis of BE was based on the history, physical examination, a serum biochemistry panel compatible with a chronic inflammatory process (e.g., hyperglobulinemia, hyperfibrinogenemia), complete blood cell count (e.g., nonregenerative anemia), echocardiographic, and necropsy findings. The echocardiographic status of each valve was established on the day of the initial examination. For 12 cows in which a diagnosis of BE was made during that period, only 6 underwent necropsy which enabled a confirmation of the diagnosis. The 6 other cows were not included in this study since the diagnosis of BE was only based on echocardiographic findings and was not confirmed by other ancillary tests. The thickness of each valve was measured three times on the echocardiogram. The echocardiographic classification of the valves was not changed after systematic measurements were performed. The determination of the valve status (affected vs. unaffected) was made by reviewing the necropsy findings of macroscopic evidence of endocarditis in the valves.
Echocardiography in the NONBE group The echocardiographic examination of 10 Holstein cows with other cardiorespiratory diseases (NONBE), were also used to assess the valvular thickness in comparison with the CONTROL and BE group. These cows were examined by the same operator (SB), using the same ultrasound unit.f A total of 3 sets of data were obtained for each group of cows and the means of these values were used for further analysis.
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Figure 1 A. Long-axis 4-chambers view. Determination of the mitral (MV) and tricuspid (TV) valve thicknesses when observing the closed valves during early ventricular systole. B. Right long-axis view of the left ventricular outflow tract. Determination of the aortic valvular thickness (Ao) during ventricular diastole. C. Right long-axis view of the right ventricular outflow tract. Determination of the pulmonic valve thickness (PV) during ventricular diastole.
Figure 2 Determination of the valvular thickness at different areas during echocardiography: application to the aortic valve. Two measures (M1 and M4) were taken at the attachment of the valve to the mural endocardium. Two measures (M2 and M3) were taken at the free extremity of the valve. The mean and maximum values were used for further analyses. Ao: aorta, LA: left atrium, LV: left ventricle, RV: right ventricle.
Bovine valvular thickness measurement
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Table 1 The mean (SD), minimal and maximal values of valvular thicknesses determined by right transthoracic echocardiography in 40 healthy Holstein early lactating cows. Group (no of cases) CONTROL (n ¼ 40)
Valve Tricuspid
Mitral
Aortic
Pulmonary
Measurement
Valve thickness (cm) Mean
SD
Min
Max
0.49 0.48 0.55 0.61 0.67 0.64 0.67 0.80 0.62 0.49 0.53 0.66 0.46 0.37 0.39 0.52
0.16 0.14 0.13 0.13 0.17 0.19 0.17 0.17 0.14 0.16 0.20 0.15 0.14 0.11 0.15 0.14
0.23 0.25 0.25 0.41 0.35 0.28 0.41 0.43 0.34 0.18 0.23 0.39 0.16 0.21 0.16 0.26
0.83 0.84 0.78 0.97 1.01 1.11 1.05 1.28 0.84 0.78 0.91 1.05 0.82 0.74 0.71 0.91
M1 M2 M3 M4 M1 M2 M3 M4 M1 M2 M3 M4 M1 M2 M3 M4
(CONTROL) healthy cows free from heart diseases used as a control group; (M1, M4) valvular thickness near the attachment of the valve to the myocardium; (M2, M3) valvular thickness at free end of the valve.
Data analysis
Results
Descriptive statistics were collected from the CONTROL, BE, and NONBE groups. The agreement between the echocardiographic classification of each valve and the final status of the valve based on necropsy was analyzed using a Kappa (k) Cohen correlation test in the BE group. The AndersoneDarling test confirmed normality in each group (CONTROL, BE and NONBE). A mixed linear model, with valve type as the fixed factor and animal identification number as the random factor (to control for possible clustering effects among individuals that provided multiple measurements), was used to determine differences in mean maximal thickness as a function of valve type in the control group. To compare mean maximal valvular thickness for each valve type across the three groups, a linear model assuming unequal variances, with group as the fixed factor was used, excluding the affected valves. In the previous statistical tests, Tukey’s post hoc tests were used to examine differences between pairs of means. The maximal valvular thicknesses of affected and unaffected valves in the BE group were compared using a ManneWhitney test due to the low numbers of data. Statistical analyses were performed using commercial software.g The level of statistical significance was set at 0.05.
In the CONTROL group, the blood cTnI levels were compatible with the absence of myocardial injury (
www.elsevier.com/locate/jvc
Echocardiographic measurement of cardiac valvular thickness in healthy cows, cows with bacterial endocarditis, and cows with cardiorespiratory diseases ´bastien Buczinski, Dr Ve ´t, MSc a,*, Mohammad Tolouei, DVM, PhD b, Se Ali Rezakhani, DVM, PhD c, Mohamed Tharwat, DVM, PhD d a
Clinique Ambulatoire Bovine, De´partement des sciences cliniques, Faculte´ de Me´decine Ve´te´rinaire, Universite´ de Montre´al, Que´bec, Canada b Department of Clinical Science, University of Tabriz, Iran c Department of Clinical Studies, School of Veterinary Medicine, Shiraz University, Shiraz, Iran d Department of Animal Medicine, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt Received 18 February 2012; received in revised form 4 June 2013; accepted 1 August 2013
KEYWORDS Heart disease; Valvular; Endocardium; Echocardiography
Abstract Objective: To determine valvular thickness in healthy cows, cows with bacterial endocarditis, and cows with various cardiorespiratory diseases. Animals: 40 healthy Holstein adult cows (CONTROL), 6 adult cows with confirmed bacterial endocarditis (BE), and 10 cows with other cardiorespiratory disorders (NONBE). Methods: Prospective study using right transthoracic echocardiographic examination in CONTROL, BE and NONBE cows. The valvular thicknesses of all cows were assessed in four different locations for all cardiac valves, and the maximal value was used for further analysis. Results: The mean [standard deviation (SD)] maximal thicknesses of the tricuspid, mitral, aortic, and pulmonary valves in the CONTROL group were 0.69 0.10 cm, 0.85 0.21 cm, 0.72 0.17 cm, and 0.58 0.12 cm, respectively. The maximal valvular thicknesses were less than 0.97 cm for the tricuspid, less than 0.91 cm for pulmonary, less than 1.05 cm for the aortic, and less than 1.28 cm for the mitral. In BE cows, the maximal valvular thickness of affected valves (median: 4.22 cm; range: 2.52e6.97 cm) and non affected valves (median: 0.75 cm; range: 0.45e1.52 cm) were significantly different (P ¼ 0.0004). The maximal valvular
* Corresponding author. E-mail address: [email protected] (S. Buczinski). 1760-2734/$ - see front matter ª 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jvc.2013.08.001
254
S. Buczinski et al. thicknesses of the NONBE valves as well as the unaffected valves in the BE group were not significantly different compared to the CONTROL group valves. Conclusions: Using the mean 2SD formula for each valve in healthy cows, a thickness of tricuspid, mitral, aortic or pulmonary valves greater than 0.85 cm, 1.27 cm, 1.06 cm or 0.82 cm respectively should raise the suspicion of valvular bacterial endocarditis. ª 2013 Elsevier B.V. All rights reserved.
Abbreviations BE cTnI SD TEE TTE
bacterial endocarditis cardiac troponin I standard deviation transesophageal echocardiography transthoracic echocardiography
Introduction Although bovine heart diseases are not highly prevalent, their clinical impact is important because the majority of these diseases have poor prognoses.1,2 Bacterial endocarditis (BE) is the most frequent valvular disease in cattle.3e5 The diagnosis of BE may be difficult due to the absence of specific clinical findings in many cases. The most common clinical sign is persistent tachycardia alongside evidence of a chronic inflammatory process on routine bloodwork.1,3,6 Heart murmurs are not always detected in cases of BE and may lack specificity.7 The presence of heart failure is uncommon in cases of BE.1e4,6,8 Because of these challenges, ancillary tests are required to make a definitive diagnosis. In other species, echocardiography is the gold standard test used for antemortem diagnosis.9,10 Transthoracic echocardiography (TTE) allows for an assessment of the consequences of valvular regurgitation, specifically cardiac dilation.9,10 The major echocardiographic findings in cases of BE classically include irregular valvular thickening with various degrees of valvular regurgitation and secondary cardiac chamber enlargement.3,11,12 Due to the fairly low sensitivity and specificity of echo findings, a classification system based upon the presence of clinical findings and results of ancillary tests has been proposed in human cardiology. This classification scheme is known as the Duke criteria13 and it is based on the presence of two levels of diagnostic criteria, the major and minor criteria. Echocardiographic findings with evidence of endocardial involvement (such as oscillating structures, abscesses or new valve
dehiscence) are considered to be major criteria in the antemortem diagnosis of BE in humans.13 To our knowledge, these criteria have not been tested or validated for bovine cases of BE. However, “typical echocardiographic” findings are commonly used in the antemortem diagnosis of bovine BE. These include different subjective findings such as valvular thickening or vegetation, valvular irregularity and/or heterogeneous appearance.2e4,8,11,12 In cattle, a recent randomeffect meta-analysis of published studies in which BE was confirmed using necropsy as the gold standard revealed that TTE had a pooled sensitivity of 84.3% (95% confidence interval: 60.4e95.0%) for BE diagnosis.14 Most of the echocardiographic examinations in published cases, however, have been performed by people with extensive experience of bovine echocardiography in hospital settings. The echocardiographic findings in bovine BE consist of various types of valvular thickening. This definition is quite subjective, especially for noncardiology board-certified veterinarians. Bovine ultrasonography is generally performed by nonspecialists, especially in farm settings, and for this reason it is important to have more objective data to define the normal thickness of cardiac valves in healthy cattle vs. cattle with BE when performing TTE. Therefore, the first aim of this study was to determine the maximal valvular thickness of the mitral, tricuspid, pulmonic, and aortic valves in healthy cows. The second objective of this study was to compare those measurements with a group of cattle with confirmed or presumed BE, or other cardiorespiratory diseases, thereby defining what should be considered valvular thickening.
Animals, materials and methods The study protocol was accepted by the ethical committee of the Faculte ´ de Me ´decine Ve ´te ´rinaire ´thique et d’Utilisation des Animaux). (Comite ´ d’E Forty adult Holstein cows, determined to be free of endocardial disease after a thorough physical examination, cardiac auscultation, and echocardiogram, were used for the determination of
Bovine valvular thickness measurement normal valvular thickness. Holstein cows from 0 to 60 days in milk were randomly selected from four tie-stall dairy farms in the area of the bovine ambulatory clinic, St-Hyacinthe, Que ´bec, Canada. They were initially selected on the basis of the absence of any disease during early lactation, and the fact that they had not received medications in the prior 14 days. The cows were then examined, paying special attention to the cardiovascular system. Cows were excluded if they showed clinical signs of illness, including fever, anorexia, decreased milk production, mastitis, or lameness. A blood sample from each cow was collected from a coccygeal vessel into a heparin-lithium tube, and cardiac troponin I (cTnI) levels were immediately assessed using a handheld analyzer.e
Echocardiography Echocardiography in the CONTROL group A standard echocardiographic examination was performed using a 3.2-MHz phased array probe,f as previously described in standing cows using a right parasternal approach.15e17 The valvular thickness measurements were always performed when the valves were closed during ventricular systole for atrioventricular valves and during ventricular diastole for semilunar valves. Particular attention was paid to the quality of the image recorded, and to measuring the closed valves when the image quality was optimal using the cine-loop mode of the ultrasound. The mitral and tricuspid valve thicknesses were measured using the long-axis four-chamber view during systole (Fig. 1A); both the septal and free-wall leaflets were measured. The aortic valve thickness was measured using the right long-axis view of the left ventricular outflow tract during diastole (Fig. 1B); both the left and right coronary cusps were measured. The pulmonic valve thickness was measured using the right long-axis view of the right ventricular outflow tract during diastole (Fig. 1C); both the anterior and right cusps were measured. Four measurements were obtained for each valve. Two measurements (M1 and M4) were taken at the attachment of the valve to the mural endocardium, with special attention to avoid valvular chordae in the measurement (Fig. 2). Two measurements (M2 and M3) were taken at the free extremity of the valve. The maximal valvular thicknesses were determined for each cardiac e f
I-Stat 1, Abaxis, Union City, CA, USA. Logiqbook, General Electric, Wawatosa, WI, USA.
255 valve. The mean maximal valvular thicknesses of the pulmonary, aortic, tricuspid and mitral valves were then determined.
Echocardiography in the BE group Between January 2007 and July 2012, every cow presented to the bovine ambulatory clinic of the Faculte ´ de Me ´decine Ve ´te ´rinaire, St-Hyacinthe, suspected of having cardiac disease underwent a complete right parasternal echocardiographic examination by the same operator (SB) with the same ultrasound unit.f Every echocardiographic examination was stored for further analysis. Echocardiograms of 12 client-owned adult Holstein cows with a diagnosis of valvular BE were reviewed by the same operator (SB). All cows underwent standard right transthoracic echocardiography15e17 during which particular attention was paid to the visualization of both semilunar and atrioventricular valves. The diagnosis of BE was based on the history, physical examination, a serum biochemistry panel compatible with a chronic inflammatory process (e.g., hyperglobulinemia, hyperfibrinogenemia), complete blood cell count (e.g., nonregenerative anemia), echocardiographic, and necropsy findings. The echocardiographic status of each valve was established on the day of the initial examination. For 12 cows in which a diagnosis of BE was made during that period, only 6 underwent necropsy which enabled a confirmation of the diagnosis. The 6 other cows were not included in this study since the diagnosis of BE was only based on echocardiographic findings and was not confirmed by other ancillary tests. The thickness of each valve was measured three times on the echocardiogram. The echocardiographic classification of the valves was not changed after systematic measurements were performed. The determination of the valve status (affected vs. unaffected) was made by reviewing the necropsy findings of macroscopic evidence of endocarditis in the valves.
Echocardiography in the NONBE group The echocardiographic examination of 10 Holstein cows with other cardiorespiratory diseases (NONBE), were also used to assess the valvular thickness in comparison with the CONTROL and BE group. These cows were examined by the same operator (SB), using the same ultrasound unit.f A total of 3 sets of data were obtained for each group of cows and the means of these values were used for further analysis.
256
S. Buczinski et al.
Figure 1 A. Long-axis 4-chambers view. Determination of the mitral (MV) and tricuspid (TV) valve thicknesses when observing the closed valves during early ventricular systole. B. Right long-axis view of the left ventricular outflow tract. Determination of the aortic valvular thickness (Ao) during ventricular diastole. C. Right long-axis view of the right ventricular outflow tract. Determination of the pulmonic valve thickness (PV) during ventricular diastole.
Figure 2 Determination of the valvular thickness at different areas during echocardiography: application to the aortic valve. Two measures (M1 and M4) were taken at the attachment of the valve to the mural endocardium. Two measures (M2 and M3) were taken at the free extremity of the valve. The mean and maximum values were used for further analyses. Ao: aorta, LA: left atrium, LV: left ventricle, RV: right ventricle.
Bovine valvular thickness measurement
257
Table 1 The mean (SD), minimal and maximal values of valvular thicknesses determined by right transthoracic echocardiography in 40 healthy Holstein early lactating cows. Group (no of cases) CONTROL (n ¼ 40)
Valve Tricuspid
Mitral
Aortic
Pulmonary
Measurement
Valve thickness (cm) Mean
SD
Min
Max
0.49 0.48 0.55 0.61 0.67 0.64 0.67 0.80 0.62 0.49 0.53 0.66 0.46 0.37 0.39 0.52
0.16 0.14 0.13 0.13 0.17 0.19 0.17 0.17 0.14 0.16 0.20 0.15 0.14 0.11 0.15 0.14
0.23 0.25 0.25 0.41 0.35 0.28 0.41 0.43 0.34 0.18 0.23 0.39 0.16 0.21 0.16 0.26
0.83 0.84 0.78 0.97 1.01 1.11 1.05 1.28 0.84 0.78 0.91 1.05 0.82 0.74 0.71 0.91
M1 M2 M3 M4 M1 M2 M3 M4 M1 M2 M3 M4 M1 M2 M3 M4
(CONTROL) healthy cows free from heart diseases used as a control group; (M1, M4) valvular thickness near the attachment of the valve to the myocardium; (M2, M3) valvular thickness at free end of the valve.
Data analysis
Results
Descriptive statistics were collected from the CONTROL, BE, and NONBE groups. The agreement between the echocardiographic classification of each valve and the final status of the valve based on necropsy was analyzed using a Kappa (k) Cohen correlation test in the BE group. The AndersoneDarling test confirmed normality in each group (CONTROL, BE and NONBE). A mixed linear model, with valve type as the fixed factor and animal identification number as the random factor (to control for possible clustering effects among individuals that provided multiple measurements), was used to determine differences in mean maximal thickness as a function of valve type in the control group. To compare mean maximal valvular thickness for each valve type across the three groups, a linear model assuming unequal variances, with group as the fixed factor was used, excluding the affected valves. In the previous statistical tests, Tukey’s post hoc tests were used to examine differences between pairs of means. The maximal valvular thicknesses of affected and unaffected valves in the BE group were compared using a ManneWhitney test due to the low numbers of data. Statistical analyses were performed using commercial software.g The level of statistical significance was set at 0.05.
In the CONTROL group, the blood cTnI levels were compatible with the absence of myocardial injury (
