Kitti Barta

The effect of sleep apnea on QT interval, QT dispersion, and arrhythmias.

QT interval (QT) and QT dispersion (QTd) are electrocardiograph (ECG) parameters for the evaluation of myocardial repolarization. The inhomogeneity of ventricular repolarization is associated with ventricular arrhythmias. An increased QT, QTd, and increased incidence of nocturnal cardiac rhythm disturbances have been described in patients with obstructive sleep apnea (OSA), while other investigators did not find a relationship between ventricular arrhythmias and OSA.

Hemodialysis and hemodiafiltration differently modulate left ventricular diastolic function

BackgroundRenal replacement therapy may have a favorable effect on diastolic left ventricular function, but it is not clear whether hemodiafiltration is superior to hemodialysis in this field. Nitric oxide (NO) and asymmetric dimethylarginine (ADMA) may play a role in the changes of intracardiac hemodynamics, but it is not clear whether the different renal replacement methods have disparate influence on the metabolism of these materials.MethodsThirty patients on renal replacement therapy were investigated. First, data was analyzed while patients received hemodiafiltration over a period of three months. Then, the same patients were evaluated during treatment with hemodialysis for at least another three months. Echocardiography was performed before and after renal replacement therapy.ResultsNo significant difference was found in the volume removals between hemodialysis and hemodiafiltration. The left atrial diameter and transmitral flow velocities (E/A) decreased significantly only during hemodiafiltration. A positive correlation was observed between the left atrial diameter and E/Ea representing the left ventricular pressure load during hemodiafiltration. Significant correlations between NO and A and E/A were observed only in the case of hemodiafiltration.ConclusionHemodiafiltration has a beneficial effect on echocardiographic markers representing left ventricular diastolic function. This could be attributed to the differences between the dynamics of volume removal and its distribution among liquid compartments.

Myocardial adrenergic innervation in patients with vasovagal syncope measured with 123I-MIBG uptake.

BackgroundData about biochemical abnormalities (catecholamines) during vasovagal syncope (VVS) are available, but adrenergic myocardial structural damage may be hypothesized as well. AimTo study the global and regional adrenergic myocardial innervations in patients with VVS that was shown by head-up tilt table testing. Patients and methodsFifteen adult patients with VVS were studied. The age of patients was 44±18 years (17–73), nine were female and six were male. According to the tilt test results, five patients had cardioinhibition, six patients had vasodepressor syncope and four patients suffered from mixed-type VVS. Ischemic heart diseases were excluded by normal 99mTc-MIBI rest–stress dipyridamol single-photon emission computed tomography (SPECT) results. A control group was formed from six healthy adult volunteers. To investigate cardiac sympathetic innervations 250–370 MBq iodine-123 meta-iodobenzylguanidine (123I-MIBG) was used. Fifteen minutes after the intravenous administration of 123I-MIBG early, and 2–3 h later, delayed planar myocardial and tomographic (SPECT) scintigraphies were performed. The heart-to-mediastinum count ratio (H/M) was calculated for both early and delayed images, together with the decay-corrected change rates. The regional 123I-MIBG uptake was visualized on SPECT slices and polar map images. The regional uptake was considered pathological below 50% compared with normal uptake sites. ResultsDelayed H/M ratios significantly depended on group (analysis of variance: P=0.005), whereas early H/M values did not. Although the decay-corrected myocardial MIBG uptake increased in time in controls, less wash-in or even wash-out could be observed in the VVS groups; however, difference from the controls was significant only in the vasodepressor group (Dunnetts t-test: P<0.05). All patients had regional 123I-MIBG uptake deficit in different regions. ConclusionIn our patients with VVS, global 123I-MIBG deficit was present frequently, and all patients had regional adrenergic nerve function deficit. These alterations may play a role in causing clinical symptoms and have importance in staging and treatment planning.

Atrial fibrillation and the autonomous nervous system

The autonomic nervous system has a crucial role in the genesis, maintenance and abruption of atrial fibrillation. The substrate and trigger mechanism of atrial fibrillation can be influenced by the changing autonomic tone. The authors summarize the current knowledge on the relationship between autonomic nervous system and atrial fibrillation. The special neuroanatomical status and the role of autonomic reflexes and baroreflex in the initiation, maintenance, and termination of arrhythmia are reviewed. Furthermore, the mechanism and consequences of autonomic effect of the curative radiofrequency catheter ablation of pulmonary vein with atrial vagal neuroablation are discussed. At the end we also summarize the pharmacologic therapy of atrial fibrillation. Classification of atrial fibrillation, as either vagal or adrenergic, has only limited impact on current management.

Végstádiumú vesebetegség és kamrai szívritmuszavarok. A hemodialízis és a hemodiafiltráció a kamrai repolarizációt eltéroen befolyásolja

Various factors (hypertension [27%], diabetes mellitus [40%]) and their cardiovascular complications play an important role in the genesis of end stage renal disease. Furthermore, primary kidney diseases (glomerulonephritis, tubulointerstitial nephritis, obstructive uropathy, analgesic nephropathy, polycystic kidney disease, autoimmune diseases) have an unfavorable effect on the cardiovascular outcome of this particular population. Increased susceptibility for arrhythmias may be caused by intermittent volume overload, metabolic disturbance, renal anemia, structural and electrophysiological changes of the myocardium, inflammatory mechanisms that may worsen the mortality statistics of these patients. A novel renal replacement method, hemodiafiltration - based on a convective transport - ensures reduced mortality that may be attributed to a decreased occurrence of arrhythmias. The aim of this paper is to review the pathogenetic factors taking part in the arrhythmogenesis of end stage renal disease and to provide diagnostic and therapeutic opportunities that can help in the prediction and prevention of arrhythmias.

Végstádiumú vesebetegség és kamrai szívritmuszavarok. A hemodialízis és a hemodiafiltráció a kamrai repolarizációt eltérően befolyásolja @@@End stage renal disease and ventricular arrhythmia. Hemodialysis and hemodiafiltration differently affect ventricular repolarization

Various factors (hypertension [27%], diabetes mellitus [40%]) and their cardiovascular complications play an important role in the genesis of end stage renal disease. Furthermore, primary kidney diseases (glomerulonephritis, tubulointerstitial nephritis, obstructive uropathy, analgesic nephropathy, polycystic kidney disease, autoimmune diseases) have an unfavorable effect on the cardiovascular outcome of this particular population. Increased susceptibility for arrhythmias may be caused by intermittent volume overload, metabolic disturbance, renal anemia, structural and electrophysiological changes of the myocardium, inflammatory mechanisms that may worsen the mortality statistics of these patients. A novel renal replacement method, hemodiafiltration - based on a convective transport - ensures reduced mortality that may be attributed to a decreased occurrence of arrhythmias. The aim of this paper is to review the pathogenetic factors taking part in the arrhythmogenesis of end stage renal disease and to provide diagnostic and therapeutic opportunities that can help in the prediction and prevention of arrhythmias.

End stage renal disease and ventricular arrhythmia. Hemodialysis and hemodiafiltration differently affect ventricular repolarization

Various factors (hypertension [27%], diabetes mellitus [40%]) and their cardiovascular complications play an important role in the genesis of end stage renal disease. Furthermore, primary kidney diseases (glomerulonephritis, tubulointerstitial nephritis, obstructive uropathy, analgesic nephropathy, polycystic kidney disease, autoimmune diseases) have an unfavorable effect on the cardiovascular outcome of this particular population. Increased susceptibility for arrhythmias may be caused by intermittent volume overload, metabolic disturbance, renal anemia, structural and electrophysiological changes of the myocardium, inflammatory mechanisms that may worsen the mortality statistics of these patients. A novel renal replacement method, hemodiafiltration - based on a convective transport - ensures reduced mortality that may be attributed to a decreased occurrence of arrhythmias. The aim of this paper is to review the pathogenetic factors taking part in the arrhythmogenesis of end stage renal disease and to provide diagnostic and therapeutic opportunities that can help in the prediction and prevention of arrhythmias.

Molecular and genetic background of sudden cardiac death

Despite recent findings on the functional, structural and genetic background of sudden cardiac death, the incidence is still relatively high in the entire population. A thorough knowledge on susceptibility, as well as pathophysiology behind the development of malignant arrhythmias will help us to identify individuals at risk and prevent sudden cardiac death. This article presents a review of the current literature on the role of altered intracellular Ca2+ handling, acute myocardial ischaemia, cardiac autonomic innervation, renin-angiotensin-aldosterone system, monogenic and complex heritability in the pathogenesis of sudden cardiac death.

Arrhythmias in patients with obstructive sleep apnea

The authors summarize the current knowledge on the types, prevalence, reasons, diagnosis and current therapy of arrhythmias occurring in patients with obstructive sleep apnea. Most of the patients with obstructive sleep apnea have nocturnal bradycardia (5-50%), paroxysmal tachyarrhythmia (atrial 35%; ventricular 0-15%), or both. The frequency of rhythm disturbances associated with the severity of the sleeping disorder. It is important to recognize the factors predisposing to arrhythmias and the early appropriate therapy of patients is essential, in order to protect patients from life threatening arrhythmias which may worsen the clinical outcome.