Cardiac Lesions in Dairy Cows with Idiopathic Atrial Fibrillation.

Abstract

ABSTRACT. Histopathological examination of the heart, particularly the right atrium including the sinoatrial (SA) node, was carried out in 9 Holstein dairy cows with idiopathic atrial fibrillation (AF; AF group) and 12 healthy cows of the same breed (control group) in order to establish the correlation between idiopathic AF and histopathological changes in the heart in dairy cows. None of the 9 cows had clinical evidence of other diseases, and they consisted of 5 cases of short-term AF which lasted a few days or weeks, and 4 cases of long-term AF which lasted more than 1 month. The pathological changes found in the present series included multifocal or fairly large areas of myocardial fibrosis in the right atrium (in all the 9 cows of the AF group and 2 of the 12 controls-however, the changes were qualitatively and quantitatively much more severe in the former group); SA nodal architecture changes (in 3 of the 4 cows with longterm AF); and atrial dilatation (in 3 of the 4 cows with long-term AF). The results suggest that the fibrotic lesions of the right atrial myocardium may represent the anatomical changes that underlie idiopathic AF in dairy cows. KEY WORDS: atrial fibrillation, bovine, heart, pathology.

Essential Role of the m2R-RGS6-IKACh Pathway in Controlling Intrinsic Heart Rate Variability

“…Indeed, the observed increase in HRV in hearts from Rgs6 −/− mice was accompanied by an increased susceptibility to AF in vivo . This is consistent with the anti-arrhythmic effects of both genetic [42] and pharmacological I KACh ablation [43], [44], as well as with the presence of constitutively-active I KACh in animals with chronic AF [45] and in human patients with AF [46].…”

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“…Larger animals (horses, cattle and giant breed dogs) are thought to be more prone to developing pAF in the absence of other diseases compared to smaller animals (other dog breeds, pigs and goats) [71][72][73]. Larger animals have a larger atrial mass, allowing more re-entry circuits to coexist [74].…”