Search PubMed⌕ Search

Biomedical subjects

S Saksena

Publications and source records attributed to S Saksena.

At least 55 records · Page 3Linked to original sources
PubMed1999

Prospective clinical evaluation of a programmed atrial stimulation protocol for induction of sustained atrial fibrillation and flutter.

UNLABELLED: We sought to define a minimum standardized protocol for induction of atrial fibrillation [AF] and/or atrial flutter. In contrast to ventricular stimulation protocols, a stimulation protocol for induction of AF or atrial flutter has not been critically evaluated. Since suppression of inducible AF or atrial flutter is used as one of the endpoints of success of pharmacologic and ablation therapies, there is an obvious need to define a minimally appropriate electrical stimulation protocol for induction of AF or atrial flutter. We prospectively evaluated 70 patients, 44 with spontaneous atrial flutter or AF and 26 controls without documented atrial arrhythmias. A standardized programmed stimulation protocol, which employed up to three atrial extrastimuli delivered at two atrial sites at two atrial drive pacing lengths, was used in attempt to reproduce sustained AF and atrial flutter. The study endpoint was induction of sustained (> 30 s) AF or atrial flutter. Sustained AF or atrial flutter was induced in 39/44 (89%) patients and 2/26 (7%) of controls (p < 0.01). The arrhythmia induced was atrial flutter in 19/21 (91%) of atrial flutter patients, AF in 17/18 (94%) AF patients, both atrial flutter and AF in 5 AF/atrial flutter patients (100%). Two patients with atrial flutter had both AF/atrial flutter and 1 patient with AF had atrial flutter induced. The arrhythmia was induced from first stimulation site in 37 patients (85%) using a single extrastimuli in 9 (20%) patients, double extrastimuli 18 (41%) patients and triple extrastimuli in 10 (23%) patients. Two patients (5%) required stimulation from second site with two and three extrastimuli, respectively. The overall sensitivity and specificity of this stimulation protocol were 89% and 92%, respectively with a positive predictive accuracy of 95%. CONCLUSIONS: 1. Up to three atrial extrastimuli and two atrial sites are needed to increase yield of AF/atrial flutter induction at electrophysiologic study. 2. Induction of either AF or atrial flutter correlates well with the presence of a similar spontaneous arrhythmia. 3. A baseline determination of the induction mode may be desirable prior to evaluation of interventions directed at AF or atrial flutter.

Aged↗
PubMed1999

Living anatomy of the atrioventricular junctions. A guide to electrophysiological mapping. A Consensus Statement from the Cardiac Nomenclature Study Group, Working Group of Arrythmias, European Society of Cardiology, and the Task Force on Cardiac Nomenclature from NASPE. North American Society of Pacing and Electrophysiology.

Current nomenclature for atrioventricular junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, while the mouth of the coronary sinus is shown as being posterior. While this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal re-entry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology, and the North American Society of Pacing and Electrophysiology. It proposes a new, anatomically sound, nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value as regards the description of the atrioventricular junctions, establishing the principles of this new nomenclature.

Atrioventricular Node↗
PubMed1999

Evaluation of antiarrhythmic drug efficacy in patients with an ICD. Unlimited potential or replete with complexity and problems?

A report from a Study group, proposed by A. J. Camm, London, of the Working Groups on Arrhythmias and Cardiac Pacing of the European Society of Cardiology; co-sponsored by the North American Society of Pacing and Electrophysiology. The Study Group was convened on 29 August 1997 at Saltsjöbaden, near Stockholm. The meeting was chaired by A. J. Camm, London, and C. M. Pratt, Houston. Based on the presentation and discussions, a first draft of the documents was prepared by C. Pratt and J. Camm which was then circulated to all members three times for their review. All members of the Study Group approved the final manuscript. This report represents the opinion of the members of this Study Group and does not necessarily reflect the official position of either society.The meeting of the Study Group was made possible by unrestricted educational grants from Medtronic, Guidant, Proctor & Gamble, Berlex and Sanofi.Also, presented, in part, at the Cardio-Renal Drugs Advisory Board meeting of the Food and Drug Administration, Bethesda, Maryland, on 30 April 1999.

Anti-Arrhythmia Agents↗
PubMed1999

Evaluation of antiarrhythmic drug efficacy in patients with an ICD: unlimited potential or replete with complexity and problems?

There are a number of novel ways in which implantable cardioverter defibrillator (ICD) endpoints can be used in clinical trials to evaluate antiarrhythmic drugs. The advances in ICD technology (storage, retrieval, and accurate interpretation of ICD electrograms) expand the potential to include the use of an ICD endpoint as a clinical surrogate for sudden death. The ICD also provides the necessary safety net to test new drugs. The frequent need for antiarrhythmic drugs in patients already fitted with an ICD (e.g., for atrial fibrillation) necessitates knowledge of the drugs' effect on defibrillator threshold. There are interpretative problems and challenges associated with all types of ICD trials. A particular difficult issue is the degree to which the results of data on antiarrhythmic drug efficacy and safety acquired in the context of an ICD endpoint trial might be extrapolated to patient populations in which the device is not used. These and other challenging issues are discussed, with the goal of enhancing the design and interpretation of clinical trials featuring ICD endpoints.

Anti-Arrhythmia Agents↗
PubMed1999

ESCWGA/NASPE/P experts consensus statement: living anatomy of the atrioventricular junctions. A guide to electrophysiologic mapping. Working Group of Arrhythmias of the European Society of Cardiology. North American Society of Pacing and Electrophysiology.

Current nomenclature for the AV junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with anteroposterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, whereas the mouth of the coronary sinus is shown as being posterior. Although this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and AV nodal reentry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology and from the North American Society of Pacing and Electrophysiology. It proposes a new, anatomically sound, nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value for description of the AV junctions and establish the principles of this new nomenclature.

Atrioventricular Node↗
PubMed1998

Regional right and left atrial activation patterns during single- and dual-site atrial pacing in patients with atrial fibrillation.

We examined the activation of the right atrium and left atrium by pacing from different atrial sites using several single- and dual-site atrial pacing modes in patients with atrial fibrillation or flutter. We also analyzed the effect of these pacing modes on fixed coupled extrastimuli in this population. Patients underwent detailed mapping of regional right atrial (RA) and left atrial (LA) sites. Bipolar pacing was performed individually from the high right atrium, coronary sinus ostium, and the distal coronary sinus, and simultaneously from the high right atrium and coronary sinus ostium (dual-site RA pacing) or high right atrium and distal coronary sinus (biatrial pacing). Extrastimuli were delivered from the high right atrium at fixed coupling intervals of 350 and 250 ms. Twenty patients with atrial fibrillation were studied. P-wave duration during pacing was significantly abbreviated by both dual-site RA and biatrial pacing (p <0.001 vs high RA pacing, respectively) but not by any other single-site atrial pacing method. Both dual-site atrial pacing modes also significantly abbreviated P wave durations for closely coupled high RA premature beats (p <0.001) in contrast to high RA pacing. During the basic pacing drive and for high RA extrastimuli, RA activation at the crista terminalis and atrial septum was comparable in sinus rhythm, high RA pacing, and in both dual-site atrial pacing methods, but was significantly delayed by coronary sinus ostial and distal coronary sinus pacing. In contrast, proximal coronary sinus activation was delayed with high RA pacing compared with all other pacing modes, and high RA extrastimuli encountered reduced conduction delay at this location with dual-site atrial pacing modes. LA activation was advanced superiorly by both single-site coronary sinus pacing methods and both dual-site atrial pacing techniques. Inferior and lateral LA activation was advanced by all pacing modes using a coronary sinus pacing site. However, earlier activation of LA sites occurred for high RA premature beats after both dual-site pacing methods (p <0.05) compared with single-site pacing modes. Incremental conduction delay at different atrial regions for closely coupled high RA extrastimuli ranged from 33% to 120% during high RA pacing and was significantly attenuated at multiple RA and LA sites by dual-site RA and biatrial pacing. Distinct global, as well as regional electrophysiologic effects, may mediate the variable antiarrhythmic effects of different and novel atrial pacing methods.

Aged↗
PubMed1998

Protective effect of Picroliv from Picrorhiza kurroa against Leishmania donovani infections in Mesocricetus auratus.

The prevalent drugs for treatment of kala azar viz. sodium stibogluconate (SSG) and pentamidine cause severe toxic side effects and acute immunosuppression in the treated individuals. Picroliv, a standardized mixture of iridoid glycosides, prepared from the alcoholic extract of the root and rhizome of Picrorhiza kurroa has shown strong hepatoprotective activity against several models of hepatotoxicity. Therefore, the present study was undertaken with an objective to study the effects of Picroliv (12.5 mg/kg x 7 days oral) alone and in combination with SSG on parasitemia, lipid peroxidation and hepatic marker enzymes of golden hamsters during Leishmania donovani infection. The results indicated a marked hepatoprotective effect of Picroliv in terms of biochemical markers, and a significant antileishmanial activity implying that it can be utilized as an adjunct to chemotherapy or in combination therapy of kala azar along with sodium stibogluconate, thus enhancing the efficacy of antileishmanials.

Administration, Oral↗
PubMed1998

Long-term outcome of patients with drug-refractory atrial flutter and fibrillation after single- and dual-site right atrial pacing for arrhythmia prevention.

OBJECTIVES: An initial crossover study comparing dual- and single-site right atrial pacing was performed followed by a long-term efficacy and safety evaluation of dual-site right atrial pacing in patients with drug-refractory atrial fibrillation (AF). Also examined was the efficacy of two single-site right atrial pacing modes (high right atrium and coronary sinus ostium) and the long-term need for cardioversion, antithrombotic and antiarrhythmic drug therapies during dual-site atrial pacing. METHODS: Thirty consecutive patients with drug-refractory symptomatic AF and documented primary or drug-induced bradycardia were implanted with a dual chamber rate-responsive pacemaker and two atrial leads. Single-site atrial pacing was performed at the high right atrium or the coronary sinus ostium. Continuous atrial pacing was maintained. RESULTS: Mean arrhythmia-free intervals increased from 9+/-10 days in the control period preceding implant to 143+/-110 days (p < 0.0001) in single-site right atrial pacing and 195+/-96 days in dual-site right atrial pacing (p < 0.005 versus single-site pacing and p < 0.0001 versus control). Dual-site right atrial pacing significantly increased the proportion of patients free of AF recurrence (89%) as compared to single-site right atrial pacing (62%, p = 0.02). High right atrial pacing and coronary sinus ostial pacing had similar efficacy for AF prevention. Effective rhythm control was achieved in 86% of patients during dual right atrial pacing. Seventy-eight percent of patients at 1 year and 56% at 3 years remained free of symptomatic AF. The need for cardioversion was reduced after pacemaker implant (p < 0.05) and antithrombotic therapy was reduced (p < 0.06) without any thromboembolic event. Coronary sinus ostial lead dislodgement was not observed after discharge. CONCLUSIONS: Atrial pacing in combination with antiarrhythmic drugs eliminates or markedly reduces recurrent AF. Prevention of AF is enhanced by dual-site right atrial pacing. High right atrial and coronary sinus ostial pacing do not differ in efficacy. Dual-site right atrial pacing is safe, achieves long-term rhythm control in most patients, decreases the need for cardioversion, and antithrombotic therapy can be selectively reduced.

Aged↗