Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The confirmation of the occurrence of supraventricular arrhythmias (SVAs) is possible only if a surface electrocardiogram (ECG) is recorded during an episode, or if SVAs occur during 24 h ambulatory monitoring (Holter). The automatic interpretation of memory functions in DDD pacemakers may be useful in this diagnostic task over longer periods of follow up. This hypothesis was tested in 384 men and 233 women (mean age = 70 +/- 11 years) who had received Chorus 6034/6035, 6234 or 7034 pacemakers (ELA Medical, Montrouge, France) with fall-back function in case of sustained SVAs. The Automatic Interpretation for Diagnostic Assistance (AIDA) algorithm included in these pacemakers was compared with 24 h Holters recorded simultaneously (D1) and with the clinical history of symptoms consistent with SVAs up to 28 days of follow up (D28). Indications for pacing were atrioventricular block (AVB) in 269 patients, sinus node dysfunction (SND) in 248, and AVB + SND in 100. SVAs were documented before implant in 199 patients (32%). Among the 617 patients included at D1, 76 (12.4%) developed at least one SVA episode, lasting between 1 min and 24 hours, simultaneously recorded on Holter and by AIDA with a 93.8% sensitivity and 94.2% specificity. Data from 354 patients were available for analysis at D28. AIDA diagnosed SVAs in 179 patients (50.6%), 104 of whom (65%) had remained asymptomatic and 117 of whom (65%) had had no SVA documented before implant. Among the 354 patients, AIDA diagnosed SVAs in 76 (21%) asymptomatic patients who had no known SVA before implant. The prevalence of SVA in our AVB population was higher than reported in previous studies: 89 patients (56.3%) with AVB had SVAs versus 90 patients (45.9%) with other diagnoses (p = 0.55). Furthermore atrial pacing was associated with fewer SVAs. These first clinical results of the AIDA study demonstrate that the memory functions of Chorus pacemakers and the AIDA software are reliable to analyze the prevalence of SVA at 1 month of follow-up. From a clinical point of view, AIDA is a valuable tool to evaluate the efficacy of antiarrhythmic therapy, particularly as it pertains to the prevention of stroke due to atrial fibrillation.
 ...
PMID:Prevalence of supraventricular arrhythmias from the automated analysis of data stored in the DDD pacemakers of 617 patients: the AIDA study. The AIDA Multicenter Study Group. Automatic Interpretation for Diagnosis Assistance. 947 82

Recently, short-term hemodynamic benefits of right ventricular outflow tract (RVOT) or proximal septum (His bundle area) pacing have been reported in comparison with traditional apical stimulation in preliminary investigations. The purpose of the present study was to compare the hemodynamics obtained during DDD pacing from ventricular apex, RVOT and proximal septum in patients with normal left ventricular function. A simultaneous hemodynamic and Doppler-echocardiographic study was performed in 21 patients (age 67 +/- 7 years) with sick-sinus syndrome (8 pts) or 2nd-3rd degree atrioventricular (AV) block (13 pts). The three stimulation sites were randomized and pacing was applied at an identical rate (84 +/- 5 beats/min) and at a constant AV delay (150 ms). Electrocardiographic, hemodynamic and Doppler-echocardiographic investigations were performed during stimulation from each site. The QRS duration did not show significant differences during DDD pacing from ventricular apex, RVOT and proximal septum. The hemodynamic measurements (systemic pressures, mean pulmonary wedge pressure, pulmonary pressures, right ventricular end-diastolic pressure, mean right atrial pressure, cardiac index, systemic vascular resistance and arteriovenous O2 difference) did not show significant differences during pacing from the three sites. Moreover, no significant differences were observed for the Doppler-echocardiographic measurements of systolic function (aortic stroke distance, left ventricular ejection fraction) and diastolic function (isovolumetric relaxion time, mitral E/A ratio, deceleration rate of the E wave). The results suggest that in patients with normal left ventricular function DDD pacing from RVOT or proximal septum does not improve cardiac function with regard to apical pacing.
 ...
PMID:Short-term hemodynamic effects of DDD pacing from ventricular apex, right ventricular outflow tract and proximal septum. 956 77

Abnormal electrical activation occurring during ventricular pacing reduces left ventricular (LV) pump function. Two strategies were compared to optimize LV function using ventricular pacing, minimal asynchrony and optimal sequence of electrical activation. ECG and hemodynamics aortic flowprobe, thermodilution cardiac output, LV pressure and its maximal rates of rise (LVdP/dtpos) and fall (LVdP/dtneg) were measured in anesthetized open-chest dogs (n = 7) with healthy hearts. The QRS duration (a measure of asynchrony of activation) was 47 +/- 5 ms during sinus rhythm and increased to 110 +/- 12 ms during DDD pacing at the right ventricular (RV) apex with a short AV interval. During pacing at the LV apex and LV base, the QRS duration was 8% +/- 7% and 15% +/- 7% (P < 0.05) longer than during RV apex pacing, respectively. Stroke volumes, LVdP/dtpos and LVdP/dtneg, however, were higher during LV apex (15% +/- 16%, 10% +/- 12% [P < 0.05], and 15% +/- 10%, respectively) and LV base pacing (11% +/- 12% [P < 0.05], 3% +/- 12%, and 3% +/- 11%, respectively) than during RV apex pacing. Systolic LV pressure was not influenced significantly by the site of pacing. Biventricular pacing (RV apex together with one or two LV sites) decreased the QRS duration by approximately 20% as compared with RV apex pacing, however, it did not improve stroke volumes, LVdP/dtpos and LVdP/dtneg beyond those during pacing at the LV apex alone. In conclusion, the sequence of electrical activation is a stronger determinant of ventricular function than the synchrony of activation. For optimal LV function the selection of an optimal single pacing site, like the LV apex, is more important than pacing from multiple sites.
 ...
PMID:Optimization of ventricular function by improving the activation sequence during ventricular pacing. 982 29

This study reports on the methods and results of applying right-sided atrioventricular (AV) pacing in 26 patients with advanced cardiomyopathy. Ten of these patients had ischemic cardiomyopathy. Of the 16 patients with nonischemic cardiomyopathy, 10 were idiopathic and 6 were due to secondary causes. The patients had a mean age of 56 +/- 12 years and a left ventricular ejection fraction of 26 +/- 11%. Two transvenous stimulation electrodes were temporarily placed in the high right atrium and right ventricle, respectively. A Swan Ganz catheter was positioned into the pulmonary artery to determine cardiac output by the thermodilution method and to measure the pressure in the pulmonary artery and right atrium. In addition, aortic pressure was measured through a catheter sheath via the right femoral artery. Systemic and pulmonary vascular resistance were calculated. Stimulation was performed in VVI and DDD pacing modes using different AV intervals (40, 80, 125, 150, 175, 200, and 250 msec). No increase of cardiac output was observed for the overall study cohort (p = 0.51). At VVI pacing, stroke volume significantly decreased from 66 +/- 20 mL to 53 +/- 13 mL (p < 0.01). We distinguished between responders who developed an increase of cardiac output of > 1 L/min (n = 12, 46%) and nonresponders (n = 14, 54%). Etiology of either ischemic or nonischemic cardiomyopathy for responders, as well as conduction disturbances (first-degree AV block, LBBB, RBBB), were equally distributed among both groups. Using an AV delay of 150 and 175 msec, responders to DDD pacing derived a significant increase in cardiac output. An AV delay of 150 msec produced both a significant increase of stroke volume and decrease of systemic vascular resistance. In 46% of patients with dilated cardiomyopathy of either ischemic or nonischemic origin, right-sided AV-sequential pacing brought about an improvement of left ventricular function in terms of enhanced cardiac output. We suggest individual testing in all patients with severe left ventricular dysfunction to find responders.
 ...
PMID:Can right-sided atrioventricular sequential pacing provide benefit for selected patients with severe congestive heart failure? 1008 54

The aim of the study was to evaluate the incidence of chronic AF in patients paced due to complete AV block. The study group consisted of 130 pts (70 F, 60 M), mean age 68.6 +/- 14.3 y in whom pacemakers were implanted in the years 1990-1998 due to III degree AV block. There were 76 pts with VVI, 24 DDD and 30 VDD modes of pacing. Follow-up period was mean. 47.6 +/- 25.9 m (7-110). Chronic AF developed in 25 pts (19.2%). In the VVI group the incidence of AF was significantly higher than in DDD and VDD groups--30.3% vs. 4.17% and 3.33% respectively, p < 0.01. Ventriculo-atrial conduction (VAC) was found in 19 pts (14.6%), but did not correlate with the development of AF. Stroke occurred in 2 pts with VVI pacing and chronic AF. In conclusion, in pts with complete AV block VDD and DDD pacing significantly reduce the incidence of chronic AF as compared to VVI.
 ...
PMID:[Incidence of atrial fibrillation in paced patients with complete atrioventricular block]. 1110 10

The aim of this study was to assess the alterations of stroke volume (SV) on the QT dispersion (QTD) as a result of different pacing modes and programmed AV delays in patients (pts) after myocardial infarction (MI) or with left ventricular hypertrophy (LVH). We studied 14 MI pts (9 M, 5 F) in mean age 72.3 +/- 3.7 yrs (Group I) and 12 pts with LVH (7 M, 5 F) in mean age 67.3 +/- 5.9 yrs (Group II), in whom DDD pacemakers were implanted due to complete atrioventricular block. The control group (Group III) consisted of 9 pts without MI or LVH. In all cases basic rate of the pacemaker was programmed at 70/min. Resting ECG showed all atrial and ventricular complexes captured. AV delay optimization was based on the measurements of SV by Doppler echocardiography. QT intervals (QTi) were measured from 12-lead ECG at 50 mm/s speed. QTD was calculated as the difference between maximal and minimal QTi. It was measured at optimal (opt. DDD, with highest SV) and "unoptimal" (unopt. DDD) programmed AV intervals and then in VVI mode (with lowest SV) after following reprogramming of the pacemaker. In Group I and II, a strong correlation between SV and QTD was found (R = 0.816 and -0.897, respectively). In control group, it was insignificant (R = -0.339). In VVI mode SV was significantly lower than in unopt. DDD (in Mi pts: 56.1 ml vs 71.1 ml, respectively, p < 0.01; in LVH pts: 64.1 ml vs 96.7 ml, respectively, p < 0.005) and QTD was significantly greater (74.8 ms vs 66.8 ms, respectively, p < 0.005 and 70.0 ms vs 53.5 ms, respectively, p < 0.005). In LVH pts or MI pts programming of different AV intervals and pacing modes significantly influences QTD.
 ...
PMID:[QT dispersion in DDD and VVI paced patients after myocardial infarction or with left ventricular hypertrophy]. 1157 20

Preventive treatments for atrial fibrillation by stimulation have been developed for several years now, mainly due to the relative failure of anti-arrhythmic treatments. They are based on the hypothetical effects of stimulation by controlling cardiac frequency, abolishing bradycardia-dependent extrasystoles, by the inhibition of atrial automatic foci with "overdrive", and by the modification of intra- or inter-atrial conduction delays as well as by remodelling the arrhythmogenic substrate. It is clear that an undeniable effect exists for the prevention of atrial fibrillation, even for the risk of cerebral vascular accident, by physiological stimulation (DDD/DDDR) compared to pure ventricular stimulation (VVI/VVIR) in a heterogenous global population of stimulated patients. For the moment, there is not sufficient proof of a positive effect for the emerging sites of cardiac stimulation, either atrial mono-site or double site in the populations at high risk of atrial fibrillation, with or without associated bradycardia. Some new prevention algorithms by "overdrive" are under development but for the moment only a few preliminary studies seem to show a slight benefit. It is clear that at present stimulation should be reserved only for cases of atrial fibrillation associated with a classic indication for implantation. In these patients it is recommended to position the probes in an optimal manner in order to counteract conduction disorders, choosing an adapted double chamber stimulator with prevention algorithms. That said, the patient should be clearly warned that the long term success rate is no more than 50%.
 ...
PMID:[Role of atrial stimulation in the treatment of paroxysmal atrial fibrillation]. 1205 52

This study evaluated the usefulness of echocardiographic evaluation in the selection of optimal atrioventricular delay (AVD) in DDD-paced patients. We discussed the influence of various AVD programming on systolic and diastolic left ventricle function. The detrimental effect of diastolic mitral regurgitation (DMR) on stroke volume was emphasized. Clinically useful echocardiographic methods of optimal AVD selection and prevention of DMR was discussed.
 ...
PMID:[The importance of echocardiographic evaluation in patients treated with cardiac pacing]. 1263 91

A 74-year-old patient was referred for a rapidly increasing pacing threshold 9 months after DDD pacemaker implantation because of symptomatic total atrioventricular (AV) block. She had a history of hypertension, diabetes with micro-angiopathy and a recent transient ischaemic attack. The paced electrocardiogram on admission had a right bundle branch block pattern and 3-dimensional transoesophageal echocardiography demonstrated passage of the lead through an atrial septal defect with a left ventricular position in addition to moderate atherosclerosis of the ascending aorta. No thrombus could be detected on the lead. Percutaneous extraction is usually not recommended because of the risk of mobilization of thrombus material. However, the risk of stroke during removal using cardiopulmonary bypass in this patient was considerably increased because of the presence of multiple independent risk factors. Therefore, percutaneous extraction using a locking device was selected and performed without complications: follow-up was uneventful.
 ...
PMID:Successful percutaneous extraction of an inadvertently placed left ventricular pacing lead. 1263 46

Invariably in every normal rat a single dose of 7, 12-dimethylbenz(a)anthracene, by mouth or injected in a vein, was found to cause apoplexy and massive necrosis in the inner zones of the adrenal cortex; the zona glomerulosa, the adrenal medulla, and a small region of cortex adjacent to the great adrenal vessels were spared from damage. DMBA caused these selective lesions in females and in males of 2 strains of rats. Hemorrhage and necrosis were observed in no organ other than the adrenal gland. Whereas adrenal glands were heavily damaged by DMBA, pituitary and ovary escaped injury by the compound. A single huge but sublethal feeding of o, p'-DDD caused degenerative changes of minor magnitude in the adrenals and only in a small percentage of rats; the property of inducing adrenal damage was not shared by other polynuclear aromatic hydrocarbons which were investigated, including strong carcinogens. Presence of adrenal medulla is not a prerequisite to damage of the adrenal cortex by DMBA. The adrenal damage occurred in rats, given DMBA, from which the pituitary had been removed but the lesions were smaller in extent and less in incidence as post-hypophysectomy atrophy of the adrenal cortex progressed. The entire DMBA molecule was necessary to induce adrenal damage; fragments of this molecule did not induce adrenal lesions. Two components which are of cardinal importance in this specific damaging effect are: (a) electronic factor; (b) steric factor. The level of isocitric dehydrogenase in adrenal is modified considerably by presence or absence of estradiol-17beta.
 ...
PMID:Selective adrenal necrosis and apoplexy induced by 7, 12-dimethylbenz(a)anthracene. 1444 80


<< Previous 1 2 3 4 5 6 7 8 Next >>