Key to Abbreviations
2D-STE Two-dimensional speckle-tracking echocardiography ADH Adrenal-dependent hyperadrenocorticism
CDMD Chronic degenerative mitral valvular disease HAC Hyperadrenocorticism
HCM Hypertrophic cardiomyopathy
PDH Pituitary- dependent hyperadrenocorticism PI Pulsatility index
RI Resistive index
Chronic Hyperadrenocorticism (HAC) causes hypertension, insulin resistance, central obesity, hyperlipidemia, coagulopathy and target organ damage (left ventricular hypertrophy, proteinuria, etc). These abnormalities enhance the global cardiovascular risk that is responsible for the increased mortality of human patients with HAC.1,2
The resistive index (RI) and pulsatility index (PI) of renal vessel and aorta, and the prevalence of albuminuria and microalbuminuria among the healthy controls, dogs with chronic degenerative mitral valvular disease (CDMD), dogs with HAC and concurrent CDMD were investigated in this study. Dogs with HAC and concurrent CDMD had significantly increased renal vascular resistance and prevalence of albuminuria than dogs with CDMD along. Increased urinary protein secretion had been reported in dogs which long-term administration of glucocorticoids and affected with HAC.14-17 Human patients with HAC had a lower glomerular filtration rate and creatinine clearance.18,19 In addition, a highly significant correlation between
endogenous glucocorticoid production and the progression rate of chronic renal failure has been reported.20 Similarly, both glomerular and tubular function are altered in dogs with HAC.17 Increased renal vascular resistance was also been found in dogs affected with HAC.21 The present study is in accord with the results of the previous studies, suggesting that dogs with HAC would have increased risk of renal injury.
Future research with longer follow-up and kidney histopathology of dogs with persistent proteinuria or higher RI/PI is needed to establish the link and assess the outcome.
Changes of left ventricular structural morphology and function in dogs affected with HAC were demonstrated by noninvasive Two-dimensional speckle-tracking echocardiography (2D-STE) technique, and changes between pituitary- dependent
were also revealed. Based on the results of this study, dogs with HAC were significant increased the prevalence of hypertension and hypertrophic cardiomyopathy (HCM) compared with age-matched non-HAC group. In dogs with HCM, dogs with ADH had significantly decreased longitudinal systolic and diastolic function, followed by dogs with PDH, then age-matched non-HAC group. This finding was similar to the studies that significantly increased prevalence of left ventricular hypertrophy and concentric remodeling was found in human patients with HAC.3-5 Subsequently functional abnormality, such as diastolic dysfunction has also been reported in human patients with HAC.6-9 According to previous studies, many factors have been found to be involved in development of HCM and myocardial dysfuncion, including the duration of HAC, hypertension and extent of myocardial fibrosis.10-13 In this study, dogs with ADH had higher blood pressure than PDH, these factor might partially explain the difference.
In the present study, injury of heart and kidney associated with HAC was demonstrated by ultrasound. While further studies are needed to clarify the exact pathophysiological mechanisms underlying increased renal RI, PI and left ventricular hypertrophy.
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