Search results for "Ventricle"
showing 10 items of 431 documents
Beziehung zwischen Kopfumfang und sonographischer Morphometrie der Ventrikelstrukturen im Neugeborenen- und Säuglingsalter
2001
AIM: To determine normal values of sonographic measurements of the brain in neonates and infants. METHOD: Cerebral ultrasonographic examinations were performed in 143 healthy newborns and infants. The size of the ventricles was determined by ascertaining distances as well as performing planimetric measurements of the ventricular area and circumference in standardized planes. RESULTS: Throughout the course of the study we observed a continous increase in size and a strong correlation with head circumference. The middle coronary plane used for the measurements allows the accurate representation of the ventricles and a more objective assessment of size. CONCLUSION: Based on the morphometric da…
Changes of plasma endothelin and growth factor levels, and of left ventricular mass, after chronic AT1-receptor blockade in human hypertension.
1998
The stimulation of autocrine and paracrine factors such as basic fibroblast- (bFGF) and platelet-derived (PDGF) growth factors mediates many of the growth-promoting actions of angiotensin II. The aim of this study was to evaluate the effect of chronic AT1-receptor blockade on plasma endothelin-1 (ET-1) and growth factors levels, and on left ventricular mass, in essential hypertension (EH). The study population consisted of 16 patients with mild-moderate EH, and 25 normotensive controls. In the EH patients under basal conditions, and after 3 and 6 months of chronic therapy with Losartan 50 mg/day, we measured serum levels of ET-1, bFGF and PDGF, and tumor necrosis factor (TNF). At the same t…
Effect of chronic exercise and ATP-sensitive potassium channel blockade on the spectral characteristics evolution of ventricular fibrillation in acut…
2013
Purpose: It has been proposed that chronic exercise produces a KATP channel blockade in ischemic myocardium. We have also reported that channel blockade and training exert very similar effects on energy required to defibrillate. In fact it is postulated that one mechanism by which exercise exerts an antiarrhythmic effect, is by blocking KATP channel. We have analyzed the evolution of spectrum characteristics of ventricular fibrillation (VF), in normoxic conditions and after acute myocardial ischemia, in isolated hearts from trained rabbits, and in hearts submitted to KATP channel blockade. Our hypothesis is that the spectrum characteristics of VF evolve similarly in trained hearts and in he…
The Activation Pattern of the Antioxidant Enzymes in the Right Ventricle of Rat in Response to Pressure Overload is of Heart Failure Type
2003
In the left ventricle subjected to pressure overload activity, the antioxidant enzymes increased at the hyperfunctional stage. During the transition to heart failure, these enzymes are down-regulated, oxidative stress increases, and apoptosis progresses. Maladaptative activation of the antioxidant enzymes at an early stage may contribute to the intrinsic vulnerability of right ventricle to pressure overload. The authors studied changes in expression and activity of the enzymes manganese and copper-zinc superoxide dismutases, glutathione peroxidase, and catalase in the right ventricle of rat following induction of pulmonary hypertension by injection of monocrotaline. Increase in the manganes…
Prevention of apoptosis by deferoxamine during 4 hours of cold cardioplegia and reperfusion: in vitro study of isolated working rat heart model.
2002
INTRODUCTION: Heart transplantation is often accompanied by multiple functional alterations, especially in reperfusion period. These are probably related to the reactive oxygen species (ROS) formation catalyzed by transition metals such as iron and copper, and thus the preservation time of the donor hearts is limited. Metabolic protection of the heart grafts is a permanent objective of numerous experiments. Recently, an iron chelator deferoxamine (DFX) was proposed as antioxidant agent for storage solutions in heart grafts. Oxidative stress is also known to mediate the apoptotic cell death in different tissues during ischemia-reperfusion. METHODS: The aim of this study was to evaluate a pos…
Simulation of left ventricular outflow tract (LVOT) obstruction in transcatheter mitral valve-in-ring replacement.
2020
Left ventricular outflow tract (LVOT) obstruction is a feared complication of transcatheter mitral valve replacement (TMVR). This procedure leads to an elongation of LVOT in the left ventricle (namely, the neoLVOT), ultimately portending hemodynamic impairment and death. This study sought to understand the biomechanical implications of LVOT obstruction in two patients who underwent TMVR as an "off-label" application of the Edwards SAPIEN 3 (S3) Ultra transcatheter heart valve (THV). A computational framework of TMVR was developed to assess the neoLVOT area and quantify the sub-aortic flow structure. We observed that the annuloplasty ring serves as the key anchor zone of S3 Ultra THV. A good…
Dofetilide effects on the inhibition by trains of subthreshold conditioning stimuli.
2004
We investigated the electrophysiological actions of dofetilide upon the ventricular myocardium to determine whether the drug modifies the inhibitory effects of subthreshold stimuli trains upon ventricular refractoriness. In nine Langendorff perfused rabbit hearts, ventricular epicardial electrodes were used to determine the following parameters at baseline and during dofetilide perfusion (0.5 micromolar): effective (ERP) and functional (FRP) refractory periods, conduction velocity (CV), wavelength (WL), and ERP prolongation (inhibitory effect) induced by subthreshold stimuli trains (STr) at pulse frequencies of 100, 300, and 600 Hz. Dofetilide significantly prolongs ventricular refractorine…
Are double potentials markers of a specific zone of the atrioventricular junction in the isolated rabbit heart?
1997
A study is made of the characteristics of the atrial potentials recorded in the Koch triangle and its proximity, their variations on modifying the site of cardiac pacing, and their usefulness as markers of a distinct zone of the AV junction. In 12 isolated and perfused rabbit heart preparations an analysis was made of the endocardial atrial electrograms recorded with a multiple electrode positioned in the AV junction. The electrograms were obtained during spontaneous rhythm and on pacing at the crista terminalis (CT), interatrial septum (IAS), left atrium, and right ventricle. Double potentials were frequently obtained. On pacing at the CT, high-low double potentials (DP [H-L]) were more fr…
Surgical management of moderate ischemic mitral valve regurgitation: Where do we stand?
2014
Ischemic mitral regurgitation (IMR) represents a common complication after myocardial infarction. The valve is anatomically normal and the incompetence is the result of papillary muscles displacement and annular dilatation, causing leaflets tethering. Functionally the leaflets present a restricted systolic motion due to tethering forces that displaces the coaptation surface toward the left ventricle apex. The patients present poor left ventricular function at the time of surgery and the severity of the mitral regurgitation increases the risk of mortality. Currently there is general agreement to treat surgically severe IMR nevertheless strong evidences for patient with moderate insufficiency…
Anthrazyklin-induzierte Kardiotoxizität: MRT des Herzens bei Kindern und Jugendlichen mit malignen Erkrankungen
2004
Purpose: Quantification of left and right ventricular function using MRI in young cancer patients treated with cardiotoxic anthracyclines. Materials and Methods: Twenty-eight patients (mean age 16.4 years) underwent cardiac MRI at 1.5 T. The study protocol consisted of morphologic T2-weighted images with fat suppression and cine steady-state free precession sequences (SSFP) for functional analysis. Seven patients were examined at the end of chemotherapy, two of them also repeatedly during therapy, and 21 patients following an average period of three years after finishing chemotherapy (range one month - 20 years) Results: The end-systolic volume index increased and the ejection fraction of t…