Herz
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In case of severely calcified ascending aorta, modified operative strategies are required in order to avoid manipulations of the aorta and minimize subsequent cerebral vascular accidents. ⋯ Only in few cases the surgical treatment of a coronary artery disease in combination with left ventricular outflow tract obstruction and heavily calcified ascending aorta has been described. Undoubtedly, creation of an apicoaortic connection is today only indicated in the adult population in a small collective with multiple previous operations or porcelain aorta.
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The beta-adrenergic receptors of the myocardium play an important role in the regulation of heart function. The beta-adrenergic receptors belong to the family of G-protein coupled receptors. Three subtypes have been distinguished (beta1-, beta2-, and beta3-adrenoceptors). The receptors consist of seven membrane-spanning domains, three intra- and three extracellular loops, one extracellular N-terminal domain, and one intracellular C-terminal tail. ⋯ In patients with dilated cardiomyopathy the beta-adrenergic responsiveness of the myocardium is diminished. It was shown that in these patients the expression of the beta1-adrenergic receptor is reduced on the mRNA and protein level. In these patients the expression of the inhibitory G-protein G(i) is increased. Furthermore, the expression of the G-protein receptor kinase is elevated. This kinase induces the uncoupling of the beta-adrenergic receptors. These alterations of the beta-adrenoceptor signal cascade may be induced by an elevated catecholamine release or by agonist-like autoantibodies directed against the beta1-adrenergic receptor found in patients with dilated cardiomyopathy. Both, permanent stimulation with catecholamines and chronic treatment with agonistic anti-beta1-adrenoceptor autoantibodies cause a reduction of the expression of the beta1-adrenoceptor on mRNA and protein level in "in vitro" experiments. Moreover, an over-expression of the beta1-adrenoceptor, the stimulatory G(s) protein, and the protein kinase A induce detrimental alterations of the cardiac function and morphology in transgenic animals. These animals developed heart failure accompanied by an increased mortality rate.
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Fabry disease is an inherited lysosomal storage disorder caused by deficiency of the enzyme alpha-galactosidase A. The enzyme deficiency results in accumulation of glycosphingolipids in the lysosomes n nearly all cell types and tissues leading to a multisystem disease. MANIFESTATIONS include painful crisis, angiokeratomas, corneal dystrophy, and hypohydrosis. The severe renal, cerebrovascular, and cardiac involvement is predominantly responsible for premature mortality in Fabry patients. The disease is X-linked and manifests primarily in hemizygous males but also heterozygous females can be affected. CARDIAC INVOLVEMENT is frequent in Fabry disease. Patients develop hypertrophic cardiomyopathy, arrhythmias, conduction abnormalities, and valvular abnormalities. Although Fabry disease leads to a complex clinical syndrome, there are studies indicating that manifestations can be limited to the heart. The isolated cardiac variant of Fabry disease seems to be more common than previously thought: around 3-6% of male patients with left ventricular hypertrophy seem to suffer from this disease variant. ⋯ Recent advances in molecular biology and genetic engineering have enabled the development of enzyme replacement therapy in Fabry disease. Results from two independent therapy studies are indeed promising: Infusion of the enzyme preparation seems to be well tolerated and effective in catabolizing the lipid deposits. This enzyme replacement therapy could be one of the first examples for causal treatment of left ventricular hypertrophy. Therefore, early diagnosis of hypertrophy patients with the cardiac variant of Fabry disease is important.
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Although several classical studies seemed to provide clear ideas on the pathophysiology of atrial fibrillation, current concepts have to be modified on the basis of more recent findings. ⋯ Based on the findings of Garrey and of Moe & Abildskov, atrial fibrillation has long been considered as the prototype of an arrhythmia being caused by multiple, random reentrant circuits, the number of which would determine the stability of the reentrant process. Local refractory and conduction properties would determine the size of individual circuits, a hypothesis quite convincing with respect to refractoriness, but so far hard to prove with respect to conduction. The finding that rapid atrial rates shorten atrial refractory periods and reverse rate adaptation (atrial remodeling) has coined the phrase "atrial fibrillation begets atrial fibrillation", indicating that any atrial tachyarrhythmia modifies the substrate in a way that favors reentry. With intracellular calcium overload being the initial trigger, down-regulation of genes encoding for calcium channels seems to primarily account for atrial remodeling. Primarily neglected concepts on the pathophysiology of atrial fibrillation suggesting single, meandering circuits or focal activity have regained attention. Atrial fibrillation as a random phenomenon is questioned not only by the dominant role of the left atrium for the maintenance of the arrhythmia, but also by most recent data demonstrating a spatio-temporal periodicity in activation patterns. Finally, ablation studies have provided convincing evidence that there is a subset of patients with focal or at least focally induced atrial fibrillation.
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Due to limitations in transthoracic and occasionally transesophageal 2-D echocardiography with respect to volumetric analysis and morphologic and functional assessment in patients with congenital malformations and valvular heart disease, additional diagnostic tools have been established. In parallel with the rapid evolution in computer technology, 3-D echocardiography has grown into a well-developed technique, such as volume-rendered 3-D reconstruction, capable of displaying dynamic morphology depicting depth of the structures, their attachment, and spatial relation to the surrounding tissue. Nevertheless, the complexity of data acquisition and data processing required for adequate dynamic 3-D echocardiographic imaging and volumetric analysis does not allow to use this approach routinely. ⋯ Volumetric analysis of the aneurysmal portion may also be helpful prior to surgical resection. 3-D echocardiography can also be recommended as a valuable additional approach to atrial septal defect (ASD), corrected transposition of the great arteries, cor triatriatum, and, within limits, to ventricular septal defect (VSD) as well. Especially with respect to ASD and VSD, the potential significance of 3-D echocardiography prior to device closure is emphasized. At present, its additional information in decision-making and the increasing number of clinical cases that can be addressed and answered already justify the clinical use of this technique.