1. Clinical examination and haemato-biochemical findings
The camels used in this study were healthy, with no history or clinical findings indicative of cardiac diseases. There were no murmurs or dysrhythmia detected by heart auscultation. The mean ± SD body temperature was 37.27 ± 1.27 oC, the respiratory rate was 15.05 ± 2.59 breaths per minute, and the heart rate was 44.09 ± 8.81 beats per minute. The average hematological values obtained after analyzing adult camel blood were RBCs (11.10 ± 1.62 × 10^6/µL), PCV (29.45 ± 0.05%), hemoglobin (14.67 ± 0.28 g/dL), MCV (37.34 ± 1.44 femtoliters), MCH (14.69 ± 0.15 pg), MCHC (43.78 ± 0.17 g/dL), WBCs (12.20 ± 2.11 × 10^3/µL), neutrophils (53.85 ± 4.26%), lymphocytes (35.73 ± 1.46%), monocytes (5.24 ± 0.47%), eosinophils (3.5 ± 1.48%), and basophils (1.5 ± 0.48%). The average values of standard biochemical parameters were total proteins (6.4 ± 0.12 g/dL), albumin (3.37 ± 0.02 g/dL), glucose (92.16 ± 1.34 mg/dL), blood urea nitrogen (BUN; 14.84 ± 0.17 mg/dL), aspartate aminotransferase (AST; 82.14 ± 3.41 IU/L), gamma-glutamyl transferase (γGT; 18.64 ± 2.24 IU/L), creatine kinase (82.69 ± 2.02 IU/L), Cardiac troponin concentration was 0.042 ± 0.06 ng/mL, calcium (10.13 ± 0.23 mg/dL), phosphorous (5.94 ± 0.67 mg/dL), sodium (162.23 ± 0.52 mM), potassium (6.54 ± 0.07 mM), and chloride (114.23 ± 0.37 mM).
Morphometric and morphologic findings
The heart of the camel appeared conical-shaped and was found to be located in the ventral third of the thoracic cavity between the 3rd and 5th intercostal spaces (ICS). The mean ± SD heart weight was 2.4 ± 1.4 kg. The heart weight/body weight ratio was [0.004 ± 0.0002 (kg/kg)]. The median, median range, 95% CI, and coefficient of variation of the grossly- and MRI-measured cardiac scores are summarized in Table (1).
Descriptive statistical analysis of the camel cardiac scores obtained from gross anatomy and MR imaging. These data represent diameter measurements (cm) measured macroscopically and on MR images. These images were collected from the cadaver hearts of clinically healthy one-humped camels (n = 12). There were no detectable cardiac abnormalities in the hearts of their corresponding live camels. Coefficient f variation (CV), coefficient interval (CI), Heart length (HL), heart base width (BW), and thickness of the right atrium (RA); left atrium (LA), right ventricle (RV), left ventricle (LV), and interventricular septum (IVS) were measured macroscopically and on MR images. LAD = left atrial diameter; RAD = right atrial diameter; RVD = right ventricular diameter; AoD = aortic diameter; TCVD = tricusped valve diameter; MVD = mitral valve diameter. NA = not available.
3. MRI findings
The normal HL, BW, RA, LA, RV, LV, IVS, LAD, RAD, RVD, and AoD were measured as shown in Table 1. The midportions of RVC, LVC, RAC, LAC, and DA were used to measure their diameters. Maximal HL was measured at the endpoints of the apex and base of the heart. Maximal CT was measured at the broadest distance between the caudal and cranial surfaces of the heart. The natural contrast of cardiac chambers and walls on MR images provided an optimal delineation for the cardiac measurements. On MR images, pericardial fat appeared bright and copious, as we observed anatomically. Compared to the transverse one, this copious fat did not allow the pericardium to be visualized in the axial plane (Fig. 1).
(A) A representative MRI image of the heart showing heart length (HL) and heart base width (BW) measurements in millimeters. (B) A representative axial cardiac MRI plane showing measurements of the right atrium (RA), left atrium (LA), right ventricle (RV), left ventricle (LV), and interventricular septum (IVS). High-intensity epicardial fat (F) and moderate-intensity myocardium (**) are also shown. (C) a representative transverse cardiac MRI plane showing the right ventricle (RV), left ventricle (LV), and interventricular septum (IVS). High-intensity epicardial fat (F) and moderate-intensity myocardium (**) are also shown. (D) 3D MR image showing the aortic dimensions
4. Anatomical findings
The cardiac structures were grossly identified and labeled, as shown in Figs. 2 and 3. The RA formed the right cranial part of the heart base and was located dorsal to the RV cranial to the origin of the pulmonary trunk. The LA formed the left caudal part of the heart base and was dorsal to the LV. Seven to eight pulmonary veins opening into the atrium caudally were found.
We also found that the left caudal portion of the ventricular size, including the cardiac apex, was formed by the LV. RV was noticed to be thinner than LV. The left and right atrioventricular (AV) orifices connected the atria and ventricles on the left and right sides, respectively. The left AV and right AV orifices had a left bicuspid (mitral) and a right tricuspid valve, respectively. The peripheral boundaries of these cusps were found attached to the AV opening. The peripheral boundaries of these cusps were found attached to the AV opening. In contrast, it appears that chordae tendineae—inelastic fibrous connective tissue strings—attach the middle edges to the ventricular wall. The chordae tendineae lines were found in the wall of the right ventricle. In the wall of the right ventricle, the chordae tendineae were found to connect the three papillary muscles to the right tricuspid valve. Two tricuspid valves were located on the interventricular septum, and the third was on the cranial ventricular wall. On the left side, the chordae tendineae appeared less in number and more prominent in size than those on the right side. Furthermore, two papillary muscles were found: one on each side. Two septo-marginal moderator bands were detected; the largest one connected the interventricular septum to papillary muscles, and the smaller one was mainly located at the apex. The trabecula carnea consisted of papillary muscle, septo-marginal band, and false tendinous. The tendinous cord, the trabecula carnea, and the fibrous rings were observed in the left and right atrioventricular orifices.
Representative macrographic images of the left (Panel A) and right (Panel B) surfaces of the heart of an adult healthy one-humped camel. Panel A: a-right ventricle; b-left ventricle; c-left auricle; d-pulmonary artery; e-aorta; f-coronary fat. Panel B: a-right ventricle; b-right auricle; c-left ventricle; d-apex; e-left auricle; f-pulmonary veins
Representative macrographic images of the interior surface of the heart (Panels A and B), the interior surface of the atrium (Panel C), and the chordae tendineae of the right ventricle (Panel D) and left ventricle (Panel E) of an adult healthy one-humped camel. Panel A: a-left ventricle; b-right ventricle; c-interventricular septum; d-apex; e-papillary muscle; f-chordae tendineae; g-cusp of left atrioventricular opening; h-left atrium; i-pectinate muscle. Panel B: a-left ventricle; b-left auricle; c-left sinus venarum cavarum; d-cusp of left atrioventricular opening; e-chordae tendineae; f-papillary muscle; g-interventricular septum; h-right ventricle; i-cusp (flap) of right atrioventricular opening; j-moderator band; k-right auricle; l-aorta (opened). Panel C: a-auricle (pectinate muscle); b-sinus venarum cavarum
Relationship between anatomical and MRI dimensions of a camel’s heart
We found strong correlations between the thickness (Fig. 4) and diameter (Fig. 5) data sets of the heart structures found on both gross and MR images. Also, we found no significant differences between the values measured on gross images and the corresponding values measured on MRI (Figs. 4 and 5). There were strong positive correlations found between the gross and MRI-derived thickness measurements for the RA (r = 0.99; P < 0.0001), RV (r = 0.95; P < 0.0001), LA (r = 0.94; P < 0.003), LV (r = 0.97; P < 0.0001), IVS (r = 0.92; P < 0.0001), HL (r = 0.94; P < 0.0001), and BW (r = 0.93; P < 0.0001).
At the same time, there was no significant difference in RAg versus RAm (p = 0.19), RVg versus RVm (P = 0.16), LAg versus LAm (P = 0.07), LVg versus LVm (P = 0.47), IVSg versus IVSm (P = 0.21), HLg versus HLm (P = 0.07), and BWg versus BWm (P = 0.09). When the diameter values were looked at, there were strong positive correlations found in RAD (r = 0.99; P < 0.0001), LVD (r = 0.99; P < 0.0001), AoD (r = 0.98; P < 0.0001), RAD (r = 0.99; P < 0.0001), or RVD (r = 0.99; P < 0.0001). At the same time, there was no significant difference in LADg versus LADm (p = 0.28), LVDg versus LVDm (P = 0.56), RADg versus RADm (P = 0.39), RVDg versus RVDm (P = 0.5), or AoDg versus AoDm (P = 0.25).
QQ plots of cardiac thickness data sets were obtained from gross (A) and MR images (B) from the normality test. Scatterplots of the thickness measurements determined from gross images versus the MRI measurements (C-I) obtained from 12 clinically normal dromedaries. The solid line represents the linear equation fitted to the data points; the corresponding r, R2, and p values are provided in each panel. Box-and-whiskers plots of RA (J), RV (K), LA (L), LV (M), IVS (N), HL (O), and BW (P) for hearts that had been obtained from the gross and MRI images. The line represents the median, the cross represents the mean, and the whiskers represent the range. Significant at p < 0.0001 and p < 0.05. Heart length (HL), heart base width (BW), and thickness of the right atrium (RA); left atrium (LA), right ventricle (RV), left ventricle (LV), and interventricular septum (IVS) were measured macroscopically and on MR images
QQ plots of cardiac diameter data sets obtained from gross (A) and MR images (B) obtained from the test of normality. Scatterplots of the thickness measurements determined from gross images versus the MRI measurements (C-G) obtained from 12 clinically normal dromedaries. The solid line represents the linear equation fitted to the data points; the corresponding r, R2, and p values are provided in each panel. Box-and-whiskers plots of LAD (H), LVD (I), RAD (J), RVD (K), and AoD (L) for hearts that had been obtained from the gross and MRI images. The line represents the median, the cross represents the mean, and the whiskers represent the range. Significant at p < 0.0001 and p < 0.05. LAD = left atrial diameter; RAD = right atrial diameter; RVD = Right ventricular diameter; AoD = aortic diameter; TCVD = tricusped valve diameter; MVD = mitral valve diameter
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