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1.
J Mol Model ; 20(11): 2494, 2014 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-25367041

RESUMEN

Electrocyclic ring opening (ERO) reaction of 2H-Oxete (oxetene) has been carried out computationally in the gas phase and ring opening barrier has been computed. When comparing the ERO reaction of oxetene with the parent hydrocarbon (cyclobutene), the ring opening of cyclobutene is found to exhibit pericyclic behavior while oxetene shows mild pseudopericyclic nature. Computation of the nucleus-independent chemical shift (NICS) of oxetene adds evidence for pseudopericyclic behavior of oxetene. By locking of lone pair of electrons by hydrogen bonding, it is seen that the pseudopericyclic nature of the ring opening of oxetene is converted into a pericyclic one. CASSCF(5,6)/6-311+G** computation was carried out to understand the extent of involvement of lone pair of electrons during the course of the reaction. CR-CCSD(T)/6-311+G** computation was performed to assess the energies of the reactant, transition state and the product more accurately.


Asunto(s)
Simulación por Computador , Compuestos Epoxi/química , Modelos Químicos , Modelos Moleculares , Electrones , Transferencia de Energía , Gases , Enlace de Hidrógeno , Estructura Molecular , Relación Estructura-Actividad
2.
J Res Pharm Pract ; 3(3): 100-3, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25328900

RESUMEN

OBJECTIVE: The pure essence of plants (essential oils) provides both psychological and physiological benefits when used accurately and safely. Conventionally, Lavender oil is known for relaxing, carminative, and sedative effects. Hence, an attempt was made to know the effect of Lavender essential oil on dental patient anxiety. METHODS: The present study included two comparison groups (Lavender and control group), each comprising five dental clinics. In Lavender group, the ambient odor of Lavender essential oil was maintained with the help of a candle warmer in the reception area and in the control group, candle warmer with normal water was used. A total of 597 patients, aged above 18 years were included. A questionnaire comprising demographic information, and a modified dental anxiety scale was given to the patients in waiting room, and data regarding anxiety levels was recorded. FINDINGS: Student's t-test (unpaired) showed a significant reduction in anxiety scores of Lavender group compared with the control group. Analysis of variances test showed reduction in anxiety scores as age increased in Lavender group. CONCLUSION: Fragrance of Lavender oil at reception area may effectively reduce the patient's state or current anxiety. This practice on routine usage can improve the quality of dental treatments.

3.
J Sci Food Agric ; 94(2): 308-15, 2014 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-23749313

RESUMEN

BACKGROUND: Several species of the genus Cassia are known for their antioxidant, antimicrobial and antidiabetic activities, but some of the lesser-known Cassia species, e.g. C. renigera, C. biflora and C. laevigata have not been studied for their biological activities. RESULTS: Methanol extract of C. laevigata was fractionated by preparative thin-layer chromatography. The resulting six different fractions were tested against Fusarium oxysporum and Aspergillus niger for their antifungal activity. Due to higher antifungal activity of fraction 1 of C. laevigata, this was further analyzed by reversed-phase high-performance liquid chromatography (RP-HPLC), resulting in distinct separation of one compound at a retention time of 7.2 min with an absorbance of 252 nm. Further, this compound was analyzed by gas chromatography-mass spectrometry (GC-MS) for its putative structural identification. Mass spectra of this compound resembled the spectra of anthraquinone 1-carboxylic acid by NIST library search. The genomic-level expression of chalcone synthase, a key enzyme involved in the biosynthesis of polyketides, was increased in C. laevigata when compared to other Cassia species. CONCLUSIONS: This study provides an insight into the higher antifungal activity of C. laevigata, including the identification of anthraquinone 1-carboxylic acid, which may be responsible for the antifungal activity.


Asunto(s)
Antraquinonas/farmacología , Antifúngicos/farmacología , Aspergillus niger/efectos de los fármacos , Cassia/química , Fusarium/efectos de los fármacos , Extractos Vegetales/farmacología , Aciltransferasas/genética , Aciltransferasas/metabolismo , Antraquinonas/análisis , Antifúngicos/análisis , Cassia/genética , Cromatografía Líquida de Alta Presión/métodos , Cromatografía de Fase Inversa/métodos , Cromatografía de Gases y Espectrometría de Masas/métodos , Estructura Molecular , Extractos Vegetales/análisis , Policétidos/metabolismo , Especificidad de la Especie
4.
J Family Med Prim Care ; 3(4): 400-3, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25657952

RESUMEN

INTRODUCTION: Obesity is a risk factor for cardiovascular disease (CVD), diabetes mellitus (DM), and hypertension (HTN). In an era of rapidly growing prevalence of obesity, it is important to explore the current knowledge, attitude, and practices of primary care physicians. MATERIALS AND METHODS: Study participants were medical officers (MOs) of primary health centers in three districts of North Karnataka. The questionnaire was developed by a review of literature in the field and validated with five participants for scope, length, and clarity. RESULTS/DISCUSSION: Of the 102 participants, only 15% were aware about the burden of obesity in India. HTN, DM, and CVD were indicated as comorbidities by 73, 78, and 60 participants, respectively. Only 25 and 12 participants indicated appropriate body mass index (BMI) cut-off values for overweight and obesity diagnosis. Of the 102 participants, 54 were not aware of the guidelines for obesity management. Practices and attitudes of the participants were encouraging. Nearly all of them felt that the adults with BMI within the healthy range should be encouraged to maintain their weight and, three-fourth of them agreed that most overweight persons should be treated for weight loss and small weight loss can achieve major medical benefit. However, nearly half of the participants' responses were stereotypical as they felt only obese and overweight with comorbidities should be treated for weight loss. Two-thirds of them use BMI to diagnose overweight/obese and nearly all of them advice their patients to increase physical activity and restrict fat. Most of the participants were advising their patients to restrict sugar intake, increase fruits and vegetable consumption, reduce red meat, and avoid alcohol consumption. CONCLUSION: Present study exposed the lack of knowledge regarding obesity. However, practices and attitudes of the participants were promising. There is a need of in-service training to MOs to further improve their knowledge and practices towards management of obesity.

5.
J Indian Soc Periodontol ; 17(2): 198-203, 2013 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-23869126

RESUMEN

BACKGROUND: The green tea extract is a naturally occurring product having beneficial effects that counteract with the pathobiological features of periodontitis and diabetes mellitus. Hence, the present study was aimed at incorporation of green tea extract into hydroxylpropyl methylcellulose and investigates its efficacy in chronic periodontitis patients associated with and without diabetes mellitus. MATERIALS AND METHODS: For the in vitro study, formulation of green tea strips and placebo strips, and analysis of drug release pattern from the green tea strips at different time intervals were performed. For the in vivo study, 50 patients (20-65 years), including 25 systemically healthy patients with chronic periodontitis (group 1) and 25 diabetic patients with chronic periodontitis (group 2) were enrolled. In each patient, test and control sites were identified for the placement of green tea and placebo strips, respectively. Gingival Index (GI), Probing Pocket Depth (PPD), and Clinical Attachment Level (CAL) were examined at baseline, first, second, third, and fourth weeks. Microbiological analysis for Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans was performed at baseline and fourth week. RESULTS: The in vitro study showed 10.67% green tea release at 30 min; thereafter, a slow release was noted till 120 min. IN VIVO STUDY: Both groups showed significant reduction in GI scores at the test sites. Group 1 showed significant (P < 0.001) PPD reduction at different time intervals at the test sites. However, group 2 showed significant reduction from baseline (5.30 ± 0.70) to fourth week (3.5 ± 0.97). Statistically significant gain in CAL at the test sites was observed both in group 1 (1.33 mm) and group 2 (1.43 mm). The prevalence of P. gingivalis in group 1 test sites was significantly reduced from baseline (75%) to fourth week (25%). CONCLUSIONS: Local drug delivery using green tea extract could be used as an adjunct in the treatment of chronic periodontitis in diabetic and non-diabetic individuals.

6.
J Stem Cells ; 8(2): 99-103, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-24698986

RESUMEN

Regeneration of bony defects caused by periodontal disease continues to be a challenge for clinicians. Application of stem cells from different tissue sources and scaffolds for regeneration have been reported in animal models but clinical studies with long term follow-ups are limited. Herein we report the three years follow-up of the application of autologous bone marrow mononuclear cells (BMMNCs) embedded in a thermo-reversible gelation polymer (TGP) for periodontal regeneration. A 23-year female patient with advanced periodontitis (class IV gingival recession, probing pocket depth (PPD) of 5 mm and 6 mm in relation to mandibular lateral and central incisors respectively, and clinical attachment level (CAL) of 13 mm) correlated with radiographic evidence of severe horizontal bone loss extending up to the apex of mandibular incisors was selected for the treatment. After debridement, the defect was implanted with BMMNCs impregnated in TGP. Then the clinical parameters and radiographic evaluation were made at periodic intervals of 6, 12, 24 and 36 months. At six months, significant improvement with the clinical parameters (PPD had reduced to 2 mm, clinical attachment level had improved by 6 mm) was observed. At 36 months, the radiograph revealed bone regeneration with improvement in vertical and horizontal bone height. Transplantation of BMMNCs in a novel TGP is safe and results in a relatively significant and stable clinical outcome in horizontal alveolar bony defects.


Asunto(s)
Células de la Médula Ósea/citología , Geles/química , Leucocitos Mononucleares/trasplante , Periodoncio/fisiología , Polímeros/química , Regeneración/fisiología , Temperatura , Trasplante de Médula Ósea , Células Inmovilizadas/citología , Células Inmovilizadas/trasplante , Femenino , Humanos , Leucocitos Mononucleares/citología , Periodoncio/diagnóstico por imagen , Periodoncio/cirugía , Radiografía , Trasplante Autólogo , Adulto Joven
7.
J Pharm Bioallied Sci ; 4(Suppl 2): S157-60, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23066240

RESUMEN

Developmental grooves are not rare and often appear on maxillary lateral and central incisors and are an important predisposing factor to localized periodontal disease. Various techniques have been adopted to eliminate the groove and regenerate lost periodontium. This report of two cases describes the technique of using the local drug delivery system with chlorehexidine and the guided tissue regeneration (GTR) to control the disease progression and regeneration.

8.
J Pharm Bioallied Sci ; 4(Suppl 2): S427-30, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23066304

RESUMEN

Progress in understanding the role of bone morphogenetic proteins (BMPs) in craniofacial and tooth development and the demonstration of stem cells in periodontal ligament have set the stage for periodontal regenerative therapy and tissue engineering. Furthermore, recent approval by the Food and Drug Administration of recombinant human BMPs for accelerating bone fusion in slow-healing fractures indicates that this protein family may prove useful in designing regenerative treatments in periodontics. In the near term, these advances are likely to be applied to periodontal surgery; ultimately, they may facilitate approaches to regenerating whole lost periodontal structures.

9.
J Investig Clin Dent ; 3(3): 232-5, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22323341

RESUMEN

Medical records have an important role in the diagnosis and planning treatment modalities of periodontal diseases. Surgical periodontal procedures can pose severe complications if the underlying systemic condition is not recorded. To substantiate this, we present a rare case of afibrinogenemia that was reported to the Department of Periodontics, Narayana Dental College, Nellore, India. The present case report gives details of fibrinogen disorder and the dental management of such cases.


Asunto(s)
Afibrinogenemia/congénito , Enfermedades Periodontales/etiología , Adulto , Afibrinogenemia/complicaciones , Afibrinogenemia/diagnóstico , Pruebas de Coagulación Sanguínea , Femenino , Humanos , Enfermedades Periodontales/diagnóstico , Enfermedades Periodontales/tratamiento farmacológico
10.
Pak J Pharm Sci ; 23(3): 279-83, 2010 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-20566440

RESUMEN

Celecoxib Transdermal patches were prepared by using different polymers such as hydroxyl-propylmethylcellulose (HPMC), methylcellulose (MC), Polyvinylpyrolidone (PVP). The in-vitro release of the drug from the formulations were studied using commercial semi permeable membrane. The prepared formulation were subjected to various physicochemical evaluation test, in-vitro dissolution studies, kinetics studies shows diffusion might be one of the prominent mechanism influencing the drug release. To confirm the fact Peppa's plot was drawn, which confirmed that the diffusion mechanism involved in the drug release was of non fickian diffusion type. ex-vivo diffusion studies by using rat skin, guinea pig skin and pig ear skin and finally in-vivo evaluation studies (the patch F4 HPMC 0.75%, PVP 0.25%) were carried out by using rabbits.


Asunto(s)
Inhibidores de la Ciclooxigenasa 2/administración & dosificación , Pirazoles/administración & dosificación , Sulfonamidas/administración & dosificación , Administración Cutánea , Animales , Celecoxib , Cobayas , Masculino , Pirazoles/química , Conejos , Ratas , Solubilidad , Sulfonamidas/química , Porcinos
11.
BMC Complement Altern Med ; 6: 32, 2006 Sep 20.
Artículo en Inglés | MEDLINE | ID: mdl-16987414

RESUMEN

BACKGROUND: The present study investigates the cardioprotective effects of Hibiscus rosa sinensis in myocardial ischemic reperfusion injury, particularly in terms of its antioxidant effects. METHODS: The medicinal values of the flowers of Hibiscus rosa sinensis (Chinese rose) have been mentioned in ancient literature as useful in disorders of the heart. Dried pulverized flower of Hibiscus rosa sinensis was administered orally to Wistar albino rats (150-200 gms) in three different doses [125, 250 and 500 mg/kg in 2% carboxy methyl cellulose (CMC)], 6 days per week for 4 weeks. Thereafter, rats were sacrificed; either for the determination of baseline changes in cardiac endogenous antioxidants [superoxide dismutase, reduced glutathione and catalase] or the hearts were subjected to isoproterenol induced myocardial necrosis. RESULTS: There was significant increase in the baseline contents of thiobarbituric acid reactive substances (TBARS) [a measure of lipid per oxidation] with both doses of Hibiscus Rosa sinensis. In the 250 mg/kg treated group, there was significant increase in superoxide dismutase, reduced glutathione, and catalase levels but not in the 125 and 500 mg/kg treated groups. Significant rise in myocardial thiobarbituric acid reactive substances and loss of superoxide dismutase, catalase and reduced glutathione (suggestive of increased oxidative stress) occurred in the vehicle treated hearts subjected to in vivo myocardial ischemic reperfusion injury. CONCLUSION: It may be concluded that flower of Hibiscus rosa sinensis (250 mg/kg) augments endogenous antioxidant compounds of rat heart and also prevents the myocardium from isoproterenol induced myocardial injury.


Asunto(s)
Antioxidantes/farmacología , Flores , Hibiscus , Daño por Reperfusión Miocárdica/prevención & control , Fitoterapia , Preparaciones de Plantas/farmacología , Administración Oral , Animales , Catalasa/metabolismo , Modelos Animales de Enfermedad , Glutatión/metabolismo , Isoproterenol , Masculino , Daño por Reperfusión Miocárdica/inducido químicamente , Miocardio/metabolismo , Miocardio/patología , Estrés Oxidativo/efectos de los fármacos , Ratas , Ratas Wistar , Superóxido Dismutasa/metabolismo , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismo
12.
J Circadian Rhythms ; 2(1): 2, 2004 Mar 25.
Artículo en Inglés | MEDLINE | ID: mdl-15043763

RESUMEN

BACKGROUND: Many behavioral and physiological variables exhibit daily rhythmicity. Few investigations of the daily rhythmicity in nociception have been conducted, and conflicting results have been obtained. The present study evaluated the daily rhythmicity in nociception in Wistar rats. METHODS: Nociception was investigated by Eddy's hot plate method, tail immersion method, and tail clip method. The latency between the noxious stimulus and the animal's response was recorded as reaction time. Separate groups of rats were tested in 4-hour intervals for 24 hours. RESULTS: There was clear daily variation in response latency. Reaction time was shortest a few hours before lights-on and longest at the light-dark transition. CONCLUSION: Nociception exhibits robust daily rhythmicity in rats. Sensitivity to pain is highest late in the dark phase of the light-dark cycle and lowest at the light-dark transition.

14.
Circulation ; 102(15): 1807-13, 2000 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-11023936

RESUMEN

BACKGROUND: Atrial electrical remodeling may be important for the initiation and perpetuation of atrial arrhythmias. Whether paroxysmal atrial flutter (AFL) and chronic AFL cause electrical remodeling of the atria has not been conclusively determined. METHODS AND RESULTS: Before radiofrequency ablation of paroxysmal AFL, 15 patients in sinus rhythm were evaluated under autonomic blockade. Lateral right atrial (LRA) effective refractory periods (ERPs) at 600 and 450 ms were measured before and at 1-minute intervals for 10 minutes after spontaneous or pace termination of a 5- to 10-minute period of induced AFL. In 10 patients with chronic AFL, LRA, septal, and coronary sinus (CS) ERPs and corrected sinus node recovery times (cSNRTs) at 600 and 450 ms were measured under autonomic blockade 15 minutes, 30 minutes, and 3 weeks after termination of chronic AFL by ablation. In the paroxysmal AFL group, LRA ERPs decreased by 18% at 600 ms and 12% at 450 ms (P:<0.01) after induced AFL and recovered to baseline over approximately 5 minutes. Atrial fibrillation developed during AFL in 3 patients and during ERP testing in 3 patients when refractoriness was at its nadir. In the chronic AFL group, LRA, septal, and CS ERPs at 3 weeks were significantly greater than at 15 and 30 minutes after termination of chronic AFL at both cycle lengths (P:<0.01). Three weeks after ablation, cSNRT decreased 35% at 600 ms (P:<0.05) and decreased 44% at 450 ms (P:<0. 05). Both ERPs and cSNRTs measured 15 and 30 minutes after ablation of chronic AFL were not significantly different. CONCLUSIONS: Both paroxysmal AFL and chronic AFL cause reversible electrical remodeling of the atria but demonstrate different time courses of recovery.


Asunto(s)
Aleteo Atrial/fisiopatología , Atrios Cardíacos/fisiopatología , Anciano , Fibrilación Atrial/etiología , Aleteo Atrial/complicaciones , Ablación por Catéter , Enfermedad Crónica , Electrofisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos
15.
J Org Chem ; 65(20): 6441-57, 2000 Oct 06.
Artículo en Inglés | MEDLINE | ID: mdl-11052087

RESUMEN

Furanoid sugar amino acids (1) were synthesized and used as dipeptide isosteres to induce interesting turn structures in small linear peptides. They belong to a new variety of designed hybrid structures that carry both amino and carboxyl groups on rigid furanose sugar rings. Four such molecules, 6-amino-2,5-anhydro-6-deoxy-D-gluconic acid (3, Gaa) and its mannonic (4, Maa), idonic (5, Iaa), and a 3,4-dideoxyidonic (6, ddIaa) congeners were synthesized. The synthesis followed a novel reaction path in which an intramolecular 5-exo S(N)2 opening of the hexose-derived terminal aziridine ring in 2 by the gamma-benzyloxy oxygen with concomitant debenzylation occurred during pyridinium dichromate oxidation of the primary delta-hydroxyl group to carboxyl function, leading to the formation of furanoid sugar amino acid frameworks in a single step. Incorporation of these furanoid sugar amino acids into Leu-enkephalin replacing its Gly-Gly portion gave analogues 8-11. Detailed structural analysis of these molecules by circular dichroism (CD) and various NMR techniques in combination with constrained molecular dynamics (MD) simulations revealed that two of these analogues, 8a and 10a, have folded conformations composed of an unusual nine-membered pseudo beta-turn-like structure with a strong intramolecular H-bond between LeuNH --> sugarC3-OH. This, in turn, brings the two aromatic rings of Tyr and Phe in close proximity, a prerequisite for biological activities of opioid peptides. The analgesic activities of 8a,b determined by mouse hot-plate and tail-clip methods were similar to that of Leu-enkephalin methyl ester. The syn disposition of the beta-hydroxycarboxyl motif on the sugar rings appears to be the driving force to nucleate the observed turn structures in some of these molecules (8 and 10). Repetition of the motif on both sides of a furanose ring resulted in a novel molecular design of sugar diacid, 2,5-anhydro-D-idaric acid (7, Idac). Bidirectional elongation of the diacid moieties of 7 with identical peptide strands led to the formation of a C2-symmetric reverse-turn mimetic 12 which displayed a very ordered structure consisting of identical intramolecular H-bonds at two ends between LeuNH --> sugar-OH, the same as in 8 and 10.


Asunto(s)
Aminoácidos/síntesis química , Dipéptidos/química , Furanos/síntesis química , Monosacáridos/síntesis química , Aminoácidos/química , Aminoácidos/farmacología , Analgésicos/síntesis química , Analgésicos/química , Analgésicos/farmacología , Animales , Dicroismo Circular , Encefalina Leucina/síntesis química , Encefalina Leucina/química , Encefalina Leucina/farmacología , Furanos/química , Furanos/farmacología , Espectroscopía de Resonancia Magnética , Ratones , Modelos Moleculares , Conformación Molecular , Imitación Molecular , Monosacáridos/química , Monosacáridos/farmacología , Dimensión del Dolor
16.
Pacing Clin Electrophysiol ; 23(7): 1156-63, 2000 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-10914373

RESUMEN

The use of dual chamber pacing in patients with atrioventricular block and paroxysmal supraventricular tachyarrhythmias may present a clinical dilemma because of the rapid and erratic triggering of ventricular pacing. To avoid this, a variety of pacing methods have now been described, including the use of retriggerable atrial refractory periods or dual demand pacing. This review details the use, advantages, and limitations of this poorly understood algorithm referred to as "pseudo-mode switching."


Asunto(s)
Algoritmos , Estimulación Cardíaca Artificial/métodos , Marcapaso Artificial , Taquicardia Paroxística/terapia , Taquicardia Supraventricular/terapia , Diseño de Equipo , Frecuencia Cardíaca/fisiología , Humanos , Periodo Refractario Electrofisiológico , Taquicardia Paroxística/fisiopatología , Taquicardia Supraventricular/fisiopatología
17.
Circulation ; 100(18): 1894-900, 1999 Nov 02.
Artículo en Inglés | MEDLINE | ID: mdl-10545434

RESUMEN

BACKGROUND: Evidence suggests that an increased incidence of atrial fibrillation occurs in patients undergoing single-chamber ventricular pacing (VVI) when compared with those undergoing single-chamber atrial pacing (AAI) or those having dual-chamber atrioventricular pacing (DDD). The mechanism for this is unknown. We hypothesized that long-term loss of atrioventricular (AV) synchrony leads to atrial electrical remodeling: a potential explanation for this difference. METHODS AND RESULTS: The study was a prospective, randomized comparison between 18 patients paced in VVI mode and 12 patients paced in DDD mode for 3 months. Under autonomic blockade, effective refractory periods (ERPs) from the lateral right atrium (RA), RA appendage, RA septum, and coronary sinus-corrected sinus node recovery times (cSNRTs), as well as P-wave duration (PWD), and biatrial diameters were measured at baseline and 3 months. The VVI group was then programmed to DDD pacing and reevaluated after a further 3 months. After long-term VVI pacing, ERPs at all 4 atrial sites increased significantly in a nonuniform fashion in association with biatrial dilatation. PWD and cSNRTs also prolonged significantly. With the reestablishment of AV synchrony, ERPs, PWD, cSNRTs, and biatrial dimensions returned to baseline levels. In the 12 patients who underwent long-term DDD pacing from baseline, no significant changes in atrial electrophysiology or biatrial dimensions were demonstrated. CONCLUSIONS: Long-term loss of AV synchrony induced by VVI pacing is associated with atrial electrical remodeling, which is reversible after the reestablishment of AV synchrony with DDD pacing. This process may be partly responsible for the higher incidence of atrial fibrillation in patients undergoing VVI pacing compared with AV sequential pacing.


Asunto(s)
Fibrilación Atrial/terapia , Nodo Atrioventricular/fisiopatología , Bloqueo Cardíaco/terapia , Marcapaso Artificial , Anciano , Estudios Cruzados , Ecocardiografía , Femenino , Bloqueo Cardíaco/fisiopatología , Humanos , Estudios Longitudinales , Masculino
18.
J Am Coll Cardiol ; 33(2): 342-9, 1999 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-9973013

RESUMEN

OBJECTIVES: This study examined the effect of brief duration atrial fibrillation on left atrial and left atrial appendage mechanical function in humans with structural heart disease. BACKGROUND: Left atrial dysfunction and the development of spontaneous echo contrast (SEC) may follow the cardioversion of atrial fibrillation (AF) to sinus rhythm. This phenomenon has been termed "stunning" and is implicated in the development of atrial thrombus and embolic stroke. The effects of brief duration AF on left atrial mechanical function in humans are unknown. METHODS: Twenty-four patients (23 men, aged 59.1+/-12.7 years) with significant structural heart disease (ejection fraction 31.2+/-9.0%, left atrial diameter 4.9+/-0.4 cm) undergoing implantation of a ventricular cardiodefibrillator underwent transesophageal echocardiography to evaluate left atrial appendage emptying velocities (LAAeV) and SEC before, during and after a 15-min period of AF induced by rapid right atrial pacing. Atrial fibrillation was then permitted to terminate spontaneously within 5 min or was reverted with an endocardial direct current shock. Velocities and SEC were assessed in sinus rhythm pre-AF, during AF and immediately, 5 and 10 min after reversion to sinus rhythm. RESULTS: Atrial fibrillation terminated spontaneously in 10 patients after 16.1+/-1.0 min. Endocardial direct current (DC) cardioversion of 10.4+/-6.4 J was required in 14 patients after AF lasting 20 min. Mean LAAeV pre-AF (50.0 +/- 17.5 cm/s) was not significantly different to LAAeV immediately (52.8 +/- 16.7 cm/s), 5 min (54.3 +/- 16.4 cm/s) or 10 min (53.7 +/- 15.7 cm/s) after reversion to sinus rhythm. Atrial stunning defined as a reduction in LAAeV of >20% was not observed in any patient. Fourteen of 24 patients (58%) developed SEC during AF, which resolved within 30 s of AF termination. There were no significant differences between LAAeV in those patients reverting with DC shock (pre-AF 50.6+/-16.2 cm/s vs. immediately post-AF 54.7+/-16.6 cm/s) or in those patients with spontaneous reversion (pre-AF 48.9+/-20.2 cm/s vs. immediately post-AF 49.8+/-17.3 cm/s). CONCLUSIONS: Significant left atrial stunning was not observed after brief duration AF in humans with structural heart disease. Transient left atrial SEC develops in a significant proportion of these patients during AF but resolves rapidly on reversion to sinus rhythm. These findings suggest that the risk of thromboembolism may be low after brief duration AF that terminates either spontaneously or with an endocardial DC shock even in patients with significant structural heart disease. These findings have important implications for recipients of implantable devices that are capable of atrial defibrillation in response to AF.


Asunto(s)
Fibrilación Atrial/fisiopatología , Función del Atrio Izquierdo , Fibrilación Atrial/diagnóstico por imagen , Fibrilación Atrial/terapia , Velocidad del Flujo Sanguíneo , Desfibriladores Implantables , Ecocardiografía Transesofágica , Cardioversión Eléctrica , Electrocardiografía , Femenino , Estudios de Seguimiento , Atrios Cardíacos/diagnóstico por imagen , Frecuencia Cardíaca , Humanos , Masculino , Persona de Mediana Edad , Contracción Miocárdica , Estudios Prospectivos
19.
J Am Coll Cardiol ; 32(2): 468-75, 1998 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-9708477

RESUMEN

OBJECTIVES: This study examined the effect of radiofrequency ablation (RFA) on left atrial (LA) and left atrial appendage (LAA) function in humans with chronic atrial flutter (AFL). BACKGROUND: Atrial stunning and the development of spontaneous echocardiographic contrast (SEC) is a consequence of electrical cardioversion of AFL to sinus rhythm. This phenomenon has been termed "stunning" and is associated with thrombus formation and embolic stroke. Radiofrequency ablation is now considered to be definitive treatment for chronic AFL, but whether this procedure is complicated by LA stunning is unknown. METHODS: Fifteen patients with chronic AFL undergoing curative RFA underwent transesophageal echocardiography to evaluate LA and LAA function and SEC before and immediately, 30 minutes and 3 weeks after RFA. To control for possible direct effects of RFA on atrial function, seven patients undergoing RFA for paroxysmal AFL were also studied. In this group, RF energy was delivered in sinus rhythm and echocardiographic parameters were assessed before and immediately and 30 minutes following RFA. RESULTS: Chronic AFL: Mean arrhythmia duration was 17.2 +/- 13.3 months. Twelve patients (80%) developed SEC following RF energy application and reversion to sinus rhythm. LAA velocities decreased significantly from 54.0 +/- 14.2 cm/s in AFL to 18.0 +/- 7.1 cm/s in sinus rhythm after arrhythmia termination (p < 0.01). These changes persisted for 30 minutes. Following 3 weeks of sustained sinus rhythm, significant improvements in LAA velocities (68.9 +/- 23.6 vs. 18.0 +/- 7.1 cm/s, p < 0.01) and mitral A-wave velocities (49.8 +/- 10.3 vs. 13.4 +/- 11.2 cm/s, p < 0.01) were evident and SEC had resolved in all patients. Paroxysmal AFL: Radiofrequency energy delivered in sinus rhythm had no significant effect on any of the above indexes of LA or LAA function and no patient developed SEC following RFA. CONCLUSIONS: Radiofrequency ablation of chronic AFL is associated with significant LA stunning and the development of SEC. Left atrial stunning is not secondary to the RF energy application itself. Sustained sinus rhythm for 3 weeks leads to resolution of these acute phenomena. Left atrial stunning occurs in the absence of direct current shock or antiarrhythmic drugs, suggesting that its mechanism may be a function of the preceding arrhythmia rather than the mode of reversion.


Asunto(s)
Aleteo Atrial/cirugía , Función del Atrio Izquierdo/fisiología , Ablación por Catéter/efectos adversos , Aturdimiento Miocárdico/etiología , Aleteo Atrial/complicaciones , Aleteo Atrial/fisiopatología , Velocidad del Flujo Sanguíneo/fisiología , Volumen Cardíaco/fisiología , Trastornos Cerebrovasculares/etiología , Enfermedad Crónica , Ecocardiografía , Ecocardiografía Transesofágica , Cardioversión Eléctrica/efectos adversos , Electrocardiografía , Estudios de Seguimiento , Cardiopatías/etiología , Frecuencia Cardíaca/fisiología , Humanos , Embolia y Trombosis Intracraneal/etiología , Masculino , Persona de Mediana Edad , Válvula Mitral/fisiopatología , Aturdimiento Miocárdico/diagnóstico por imagen , Aturdimiento Miocárdico/fisiopatología , Trombosis/etiología
20.
Pacing Clin Electrophysiol ; 21(6): 1258-67, 1998 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-9633069

RESUMEN

Several large prospective randomized trials have demonstrated that anticoagulation with warfarin reduces the risk of thromboembolic stroke in high risk patients with chronic AF by approximately 70%. Large numbers of patients with permanent pacemakers have AF, and anticoagulation rates in this population have not been described. In a prospective analysis of 110 consecutive patients attending the pacemaker clinic of a large university hospital we assessed the number of patients with AF and the proportion of these patients who were receiving anticoagulation to prevent thromboembolic stroke. Where necessary, temporary pacemaker reprogramming to low ventricular rates was utilized to facilitate the diagnosis of AF. Fifty-three of the 110 patients (48%) were diagnosed with AF, all of whom (100%) had accepted high risk factors for thromboembolic stroke. Only eight of the 53 (15%) had been anticoagulated with warfarin. Thirty-six of the 53 patients (68%) diagnosed with AF had no prior documented diagnosis of chronic AF, and the majority had no symptoms suggesting AF. A single lead II ECG was insufficient in 67 of the 110 patients (61%) to diagnose the underlying atrial rhythm; the remainder required 12-lead ECGs or temporary pacemaker reprogramming to low ventricular rates to diagnose the underlying atrial rhythm. AF is common in patients with permanent pacemakers. It is commonly asymptomatic, and anticoagulation is markedly underutilized in reducing stroke risk in these patients. Attention to the possibility of AF in paced patients should allow prompt diagnosis and allow both the initiation of anticoagulation in order to reduce thromboembolic stroke risk and consideration for cardioversion of AF to sinus rhythm.


Asunto(s)
Anticoagulantes/uso terapéutico , Fibrilación Atrial/tratamiento farmacológico , Trastornos Cerebrovasculares/prevención & control , Marcapaso Artificial , Anciano , Aspirina/uso terapéutico , Fibrilación Atrial/diagnóstico , Fibrilación Atrial/epidemiología , Fibrilación Atrial/etiología , Electrocardiografía , Femenino , Humanos , Masculino , Marcapaso Artificial/efectos adversos , Prevalencia , Estudios Prospectivos , Factores de Riesgo , Warfarina/uso terapéutico
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