Search results for "rate control"

Rate vs. rhythm control and adverse outcomes among European patients with atrial fibrillation

2018

Aim The impact of rate and rhythm control strategies on outcomes in patients with atrial fibrillation (AF) remains controversial. Our aims were: to report use of rate and rhythm control strategies in European patients from the EURObservational Research Program AF General Pilot Registry. Secondly, to evaluate outcomes according to assigned strategies. ........................................................................................................................................................... Methods and results Use of pure rate and rhythm control agents was described according to European regions. 1-year follow-up data were reported. Among rate control strategies, beta-blockers …

Role of Rate Control and Regularization Through Pacing in Patients With Chronic Atrial Fibrillation and Preserved Ventricular Function: The VRR Study

2006

Aim: High heart rates in chronic atrial fibrillation (CAF) is one of the factors responsible for hemodynamic alterations and may lead to tachycardiomyopathies. The ventricular rate regulation (VRR) study evaluates the effect of ventricular rate regularization in CAF patients with preserved ventricular function, marked ventricular rate variability, and indications for pacemaker (PM) implantation owing to symptomatic pauses. Rate regularization was achieved using VRR algorithm (INSIGNIA® pacemakers, Guidant Corp., St. Paul, MN, USA). Methods: One month after PM implantation, 58 patients followed two 3-month crossover periods (VRR-OFF; VRR-ON) in which the VRR algorithm was randomized and comp…

Linfomas malignos primários nas glandulas salivares

2011

Primary malignant lymphomas in the salivary glands are relatively rare. Clinical presentation is not characteristic and the disease is often overlooked resulting in diagnosis and treatment delays. AIM: To stress the importance of the diagnostic process and combined management, we present a series of eight patients with malignant lymphoma of the parotid who were diagnosed only after surgery and managed with radiation and chemotherapy. METHODS: Retrospective series of patients with primary malignant lymphoma of the parotid gland managed with radiotherapy and diagnostic surgical partial resection. RESULTS: After treatment completion we achieved a loco-regional control rate of 87.5%. Toxicity w…

Prognosis, disease progression, and treatment of atrial fibrillation patients during 1 year: follow-up of the Euro Heart Survey on Atrial Fibrillation

2008

Aims: To gain insight in the prognosis and treatment of atrial fibrillation (AF) patients during 1-year follow-up in the Euro Heart Survey (EHS) on AF. Methods and results: The EHS enrolled 5333 AF patients in 2003-2004. One-year follow-up data were available for 80%. Of first detected AF patients, 46% did not have a recurrence during 1 year, paroxysmal AF largely remained paroxysmal AF (80%), and 30% of persistent AF progressed to permanent AF. Many treatment changes occurred since baseline. Oral anticoagulation was started in 19% and discontinued in 16% of all patients. Of patients initially on rhythm control 27% did not receive rhythm control during follow-up, whereas 15% of patients ini…

Drying rate control in microwave assisted processing of sliced apples

2018

The most enhanced microwave systems for the preparation of quality-dehydrated fruits continuously adjust the power level in order to maintain the product temperature above a target value. As a result, typical drying curves that exhibit high drying rates in the middle stage are obtained. This can often lead to quality damage or undesirable changes on food colour and texture. In response to these issues, a microwave system is proposed that can realise drying processes keeping drying rates constant. This approach required a continuous temperature adjustment of the apple slices under test, whose temperature was detected by a computer-aided infrared thermography system. Since temperature correct…

Performance Evaluation of a new Adaptive Packet Marking Scheme for TCP over DiffServ Networks

2004

In differentiated services (DiffServ) networks, packets may receive a different treatment according to their differentiated services code point (DSCP) label. As a consequence, packet marking schemes can be devised to differentiate packets belonging to the same TCP flow, with the goal of improving the experienced performance. The paper presents an extensive performance evaluation of a new adaptive packet marking scheme, applied to a traffic scenario composed of TCP flows with different lengths. The proposed marking scheme is most efficient when applied to a scenario composed of all long-lived flows. In a realistic mixed traffic scenario, composed of both long-lived and short-lived TCP flows,…

An analytical model of a new packet marking algorithm for TCP flows

2005

In Differentiated Services networks, packets may receive a different treatment according to their Differentiateo Services Code Point (DSCP) label. As a consequence, packet marking schemes can also be devised to differentiate packets belonging to a same TCP flow, with the goal of improving the performance experienced. This paper presents an analytical model for an adaptive packet marking scheme proposed in our previous work. The model combines three specific sub-models aimed at describing (i) the TCP sources aggregate, (ii) the marker, and (iii) the network status. Preliminary simulation results show quite accurate predictions for throughput and average queue occupancy. Besides, the research…

FALCON - joint fair airtime allocation and rate control for DASH video streaming in software defined wireless networks

2020

Software Defined Wireless Networks offer an opportunity to enhance the performance of specific services by applying centralized mechanisms which make use of a global view of the network resources. This paper presents FALCON, a novel solution that jointly optimizes fair airtime allocation and rate recommendations for Server and Network Assisted DASH video streaming, providing proportional fairness among the clients. Since this problem is NP-hard, FALCON introduces a novel heuristic algorithm that is proved to achieve almost optimal results in a practical amount of time. The performance of FALCON is evaluated when used in conjunction with three referent Adaptive Bit Rate strategies (PANDA, BO…

Is there a role for verapamil beyond rate control in paroxysmal atrial fibrillation?

2021

Poincaré surface profile. Novel non-invasive method to detect preferential ventricular response during atrial fibrillation

2007

The strategy of rate control during atrial fibrillation (AF) essentially deals with efforts to utilize and adjust the filtering properties of the atrioventricular (AV) node, allowing AF to continue and ensure that ventricular rate is controlled. In this work, a new tool based on the 3D Poincare plots is developed for the characterization of the ventricular response (VR) and the clinical evaluation of rate control therapies. Mechanisms underlying atrioventricular conduction during AF remain unclear. The role of the dual pathway AV nodal electrophysiology and the effects of the AV node modifications are still being an incognita. RR interval clusters exhibiting harmonic behaviour have been qua…