GEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 2 2007
MAXIM OGURTSOV
ABSTRACT. Six millennial proxy records of temperature in the northern hemisphere were analysed using both the Fourier and wavelet approaches. We found that the analysed temperature proxies have appreciable synchrony at multidecadal and centennial time scales. These data also show evidence for the presence of a roughly regular large-scale rhythm with a periodicity of 50,130 years in the climate of the northern hemisphere over the last millennium. It is shown that the amplitude of this variation might reach 0.20,0.28°C and contribute appreciably to the rise of global temperature over the first part of the 20th century. Possible origins of the global centennial climatic cycles are discussed. [source]

DIEL RHYTHM OF ALGAL PHOSPHATE UPTAKE RATES IN P-LIMITED CYCLOSTATS AND SIMULATION OF ITS EFFECT ON GROWTH AND COMPETITION1

JOURNAL OF PHYCOLOGY, Issue 4 2002
Chi-Yong Ahn
Oscillations in the phosphate (Pi) uptake rates for three species of green algae were examined in a P-limited cyclostat. For Ankistrodesmus convolutus Corda and Chlorella vulgaris Beyerinck, the Pi uptake rates increased during the daytime and decreased at night. In contrast, Chlamydomonas sp. exhibited the opposite uptake pattern. Cell densities also oscillated under a light:dark cycle, dividing at a species-specific timing rather than continuously. In general, the cell densities exhibited an inverse relationship with the Pi uptake rates. A competition experiment between A. convolutus and C. vulgaris in a P-limited cyclostat resulted in the dominance of C. vulgaris, regardless of the relative initial cell concentrations. Chlorella vulgaris also dominated in a mixed culture with Chlamydomonas sp., irrespective of the initial seeding ratio and dilution rate. However, Chlamydomonas sp. and A. convolutus coexisted in the competition experiment with gradual decrease of Chlamydomonas sp. when equally inoculated. Mathematical expressions of the oscillations in the Pi uptake rate and species-specific cell division gate were used to develop a simulation model based on the Droop equation. The simulation results for each of the species conformed reasonably well to the experimental data. The results of the competition experiments also matched the competition simulation predictions quite well, although the experimental competition was generally more delayed than the simulations. In conclusion, the model simulation that incorporated the effect of diel rhythms in nutrient uptake clearly demonstrated that species diversity could be enhanced by different oscillation patterns in resource uptake, even under the condition of limitation by the same resource. [source]

The Use of Anatomic M-Mode Echocardiography to Determine the Left Atrial Appendage Functions in Patients with Sinus Rhythm

ECHOCARDIOGRAPHY, Issue 2 2005
Yekta Gurlertop M.D.
Left atrial appendage (LAA) contractile dysfunction is associated with thrombus formation and systemic embolism. LAA function is determined by its flow velocities and fractional area change. This study was performed in order to determine the LAA functions with the anatomic M-mode echocardiography (AMME). Our study comprised 74 patients who had sinus rhythm and underwent transesophageal echocardiography (TEE) for various reasons. LAA fractional change (LAAFAC) was measured by manual planimetry in a transverse basal short-axis approach and LAA emptying and filling velocities also were measured. The AMME values were determined by an M-mode cross section from a cursor placed beneath the orifice of the LAA in transverse basal short-axis imaging. From these values LAA fractional shortening (LAAFS) and ejection fraction (LAAEF) were calculated. LAAEF was calculated by the Teicholz method. The comparisons were conducted, and no correlations between the LAA late filling and the anatomic M-mode values were found (for LAAFS r = 0.18; P > 0.05 and for LAAEF r = 0.19; P > 0.05). There were significant but poor correlations among the LAA late emptying with the anatomic M-mode measurements (for LAAFS r = 0.26; P < 0.05 and for LAAEF r = 0.30; P < 0.01), whereas, there were significant and good correlations between the LAAFAC and the anatomic M-mode values (for LAAFS r = 0.75; P < 0.01 and for LAAEF r = 0.78; P < 0.01). There were significant differences between the valvular heart disease group and the normal group, and between the valvular heart disease group and the ASD group (for LAAFAC P < 0.01, for LAAEF P < 0.01, for LAAFS P < 0.01). There was no difference between the normal group and the ASD group. Our study showed that the LAAEF and LAAFS in patients with sinus rhythm obtained via anatomical M-mode echocardiography is a new method, which can be used instead of left atrial appendage area change. [source]

Predictors for Maintenance of Sinus Rhythm after Cardioversion in Patients with Nonvalvular Atrial Fibrillation

ECHOCARDIOGRAPHY, Issue 5 2002
Ökçün M.D.
Recurrence of atrial fibrillation (AF) after cardioversion (CV) to sinus rhythm (SR) is determined by various clinical and echocardiographic parameters. Transesophageal echocardiographic (TEE) parameters have been the focus of clinicians' interests for restoring and maintaining SR. This study determined the clinical, transthoracic, and TEE parameters that predict maintenance of SR in patients with nonvalvular AF after CV. We enrolled 173 patients with nonvalvular AF in the study. TEE could not be performed in 26 patients prior to CV. Twenty-five patients had spontaneously CV prior to TEE. Six patients were excluded because of left atrial (LA) thrombus assessed by TEE. CV was unsuccessful in 6 patients. The remaining 110 consecutive patients (56 men, 54 women, mean age 69 ± 9 years), who had been successfully cardioverted to SR, were prospectively included in the study. Fifty-seven (52%) patients were still in SR 6 months after CV. Age, gender, the configuration of the fibrillation wave on the electrocardiogram, pulmonary venous diastolic flow, and the presence of diabetes, hypertension, coronary artery disease, mitral annulus calcification, and mitral valve prolapse (MVP) did not predict recurrence. Duration of AF, presence of chronic obstructive pulmonary disease (COPD), LA diameter, left ventricular ejection fraction (EF), left atrial appendage peak flow (LAAPF), LAA ejection fraction (LAAEF), pulmonary venous systolic flow (PVSF), and the presence of LA spontaneous echo contrast (LASEC) predicted recurrence of AF 6 months after CV. In multivariate analysis, LAAEF < 30% was found to be the only independent variable (P < 0.0012) predicting recurrence at 6 months after CV in patients with nonvalvular AF. LAAEF more than 30% had a sensitivity of 75% and a specificity of 88% in predicting maintenance of SR 6 months after CV in patients with nonvalvular AF. In conclusion, TEE variables often used to determine thromboembolic risk also might be used to predict the outcome of CV. [source]

Metabolic Heat Production, Heat Loss and the Circadian Rhythm of Body Temperature in the Rat

EXPERIMENTAL PHYSIOLOGY, Issue 3 2003
Roberto Refinetti
Metabolic heat production (calculated from oxygen consumption), dry heat loss (measured in a calorimeter) and body temperature (measured by telemetry) were recorded simultaneously at 6 min intervals over five consecutive days in rats maintained in constant darkness. Robust circadian rhythmicity (confirmed by chi square periodogram analysis) was observed in all three variables. The rhythm of heat production was phase-advanced by about half an hour in relation to the body temperature rhythm, whereas the rhythm of heat loss was phase-delayed by about half an hour. The balance of heat production and heat loss exhibited a daily oscillation 180 deg out of phase with the oscillation in body temperature. Computations indicated that the amount of heat associated with the generation of the body temperature rhythm (1.6 kJ) corresponds to less than 1% of the total daily energy budget (172 kJ) in this species. Because of the small magnitude of the fraction of heat balance associated with the body temperature rhythm, it is likely that the daily oscillation in heat balance has a very slow effect on body temperature, thus accounting for the 180 deg phase difference between the rhythms of heat balance and body temperature. [source]

Rhythm in Mother-Infant Interactions

INFANCY, Issue 2 2003
Deborah F. Deckner
Rhythmic behavior and the association of vocal rhythmic behavior with language development were studied in a sample of 30 mother-infant dyads. Dyads were observed in 2 contexts (1 involved sharing pictures and the other sharing musical toys) when infants were 18 and 24 months of age. Vocal rhythmic behavior was seen in both contexts, and in both contexts mothers matched their infant's vocal rhythmic behavior at greater than chance rates. Greater matching tended to be associated with higher language scores whereas, counter to prediction, higher rates of maternal vocal rhythmic behavior tended to be associated with lower language scores. At 24 months of age, mother-daughter dyads showed more matching than mother-son dyads. These results suggest that differences in maternal production of vocal rhythmic behavior may foster different language learning strategies. [source]

Pathophysiology and Disease Progression of Atrial Fibrillation: Importance of Achieving and Maintaining Sinus Rhythm

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2008
F.A.C.C., MARC COHEN M.D.
Atrial fibrillation (AF) is a progressive disease in which arrhythmia-induced remodeling facilitates evolution from paroxysmal AF to persistent and permanent AF. Changes in electrical, structural, and contractile properties of cardiac tissue that are thought to underlie AF maintenance and progression are reviewed. Also examined is the negative impact of AF on clinical outcomes, as well as the potential benefits of restoration and maintenance of sinus rhythm. Because of the limited efficacy and adverse effects of current antiarrhythmics, new antiarrhythmic drugs need to be developed that provide safer and more effective rhythm control in AF. [source]

A Novel Finding,Isolated Marshall's Ligament Rhythm After Catheter Ablation and Reconnection of the Marshall's Ligament with the Left Atrium After an Adenosine Bolus in One Patient with Atrial Fibrillation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2007
TA-CHUAN TUAN M.D.
No abstract is available for this article. [source]

High-Density Mapping of Left Atrial Endocardial Activation During Sinus Rhythm and Coronary Sinus Pacing in Patients with Paroxysmal Atrial Fibrillation

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2004
TIMOTHY R. BETTS M.D.
Introduction: This study was designed to record global high-density maps of left atrial endocardial activation during sinus rhythm and coronary sinus pacing. Method and Results: Noncontact mapping of the left atrium was performed in nine patients with paroxysmal atrial fibrillation undergoing pulmonary vein ablation procedures. High-density isopotential and isochronal activation maps were superimposed on three-dimensional reconstructions of left atrial geometry. Mapping was repeated during pacing from sites within the coronary sinus. Earliest left atrial endocardial activation occurred anterior to the right pulmonary veins in seven patients and on the anterosuperior septum in two patients. A line of conduction block was seen in the posterior wall and inferior septum in all patients. The direction of activation in the left atrial myocardium overlying the coronary sinus was different from the electrogram sequence in the coronary sinus catheter in 6 of 9 patients. During coronary sinus pacing, activation entered the left atrium a mean (SD) of 41 (13) ms after the pacing stimulus at a site 12 (10) mm from the endocardium overlying the pacing electrode. Lines of conduction block were present in the posterior wall and inferior septum. Conclusion: In patients with paroxysmal atrial fibrillation, lines of conduction block are present in the left atrium during sinus rhythm and coronary sinus pacing. Electrograms recorded in the coronary sinus infrequently correspond to the direction of activation in the overlying left atrial myocardium. [source]

Should We Control Rate or Rhythm in Atrial Fibrillation?

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2003
ALBERT L. WALDO M.D.
[source]

Entrainment of Ventricular Tachycardia by Sinus Rhythm

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 2 2002
JOHN M. MILLER M.D.
[source]

Accelerated Junctional Escape Rhythm with Retrograde P Waves Through Alternating Slow and Fast Pathways

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 7 2001
ALAN ACKERMANN D.O.
[source]

Relationship of Specific Electrogram Characteristics During Sinus Rhythm and Ventricular Pacing Determined by Adaptive Template Matching to the Location of Functional Reentrant Circuits that Cause Ventricular Tachycardia in the Infarcted Canine Heart

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 4 2000
EDWARD J. CIACCIO Ph.D.
Localization of Reentrant Circuits. Introduction: It would be advantageous, for ablation therapy, to localize reentrant circuits causing ventricular tachycardia by quantifying electrograms obtained during sinus rhythm (SR) or ventricular pacing (VP). In this study, adaptive template matching (ATM) was used to localize reentrant circuits by measuring dynamic electrogram shape using SR and VP data. Methods and Results: Four days after coronary occlusion, reentrant ventricular tachycardia was induced in the epicardial border zone of canine hearts by programmed electrical stimulation. Activation maps of circuits were constructed using electrograms recorded from a multichannel array to ascertain block line location. Electrogram recordings obtained during SR/AP then were used for ATM analysis. A template electrogram was matched with electrograms on subsequent cycles by weighting amplitude, vertical shift, duration, and phase lag for optimal overlap. Sites of largest cycle-to-cycle variance in the optimal ATM weights were found to be adjacent to block lines bounding the central isthmus during reentry (mean 61.1% during SR; 63.9% during VP). The distance between the mean center of mass of the ten highest ATM variance peaks and the narrowest isthmus width was determined. For all VP data, the center of mass resided in the isthmus region ocurring during reentry. Conclusion: ATM high variance measured from SR/AP data localizes functional block lines forming during reentry. The center of mass of the high variance peaks localizes the narrowest width of the isthmus. Therefore, ATM methodology may guide ablation catheter position without resorting to reentry induction. [source]

Patterns of Accelerated Junctional Rhythm During Slow Pathway Catheter Ablation for Atrioventricular Nodal Reentrant Tachycardia: Temperature Dependence, Prognostic Value, and Insights into the Nature of the Slow Pathway

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2000
ALAN B. WAGSHAL M.D.
Slow Pathway Accelerated Junctional Rhythm. Introduction: Although accelerated junctional rhythm (AJR) is a knuwn marker for successful slow pathway (SP) ablation sites. AJR may just be a regional effect of the anisotropic conduction properties of this area of the heart. We believe that detailed assessment of the AJR might provide insight into the SP specificity of this AJR and perhaps the nature of the SP itself. Methods and Results: Our ablation protocol consisted of 30-second, 70°C temperature-controlled ablation pulses with assessment after each pulse. Serial booster ablations were performed at the original successful site and at least 2 to 3 nearby sites to assess for residual AJR after the procedure in 50 consecutive SP ablations. We defined three distinct patterns of AJR: continuous AJR that persisted until the end of energy delivery (group 1, 25 patients); alternating or "stuttering" AJR that persisted throughout energy delivery (group II, 9 patients); and AJR that ended abruptly during energy delivery (group III, 16 patients). Mean ablation temperatures in the three groups was 57°± 5°C, 54°± 5°C, and 63°± 5°C, respectively (P = 0.0002 for groups I and II vs group III). Ten of 34 (29%) patients in groups I and II ("low-temperature ablation") exhibited residual SP (jump and/or single echo heats) despite tachycardia noninducibility, and 25 of 34 (73%) patients had residual AJR during the booster ablations, but neither of these was seen in any group III patients. Conclusion: Ablation temperature correlates with the pattern of AJR produced during SP ablation. That higher temperature lesions simultaneously abolish all SP activity as well as the focus of AJR suggests that this AJR is specific for the SP and is not a nonspecific regional effect. [source]

Ultradian Corticosterone Rhythm and the Propensity to Behave Aggressively in Male Rats

JOURNAL OF NEUROENDOCRINOLOGY, Issue 10 2000
J. Haller
Abstract Ultradian fluctuations in plasma glucocorticoids have been demonstrated in a variety of species including humans. The significance of such rhythms is poorly known, although disorganized ultradian glucocorticoid rhythms have been associated with behavioural disorders. Here we report that ultradian glucocorticoid rhythms may establish the propensity to behave aggressively in male rats. Male rats were significantly more aggressive in the increasing phase of their corticosterone fluctuation when confronting a male intruder than counterparts in the decreasing phase of their corticosterone fluctuations facing such opponents. Corticosterone fluctuations were mimicked by a combination of treatments with the corticosterone synthesis inhibitor metyrapone and corticosterone. Again, males with increased plasma corticosterone levels were more aggressive than counterparts with a decreased plasma corticosterone concentration. These data suggest that the behavioural response to an aggressive challenge may vary in the same animal across the day due to the pulsating nature of corticosterone secretion. Aggressive behaviour is also episodic in humans; moreover, intermittent explosive behaviour is recognized as a psychological disorder. It can be hypothesized that a temporal coincidence between the occurrence of a challenge and a surge in plasma corticosterone concentration may be one of the factors that promote episodic aggressive outbursts. [source]

Developmental Alcohol Exposure Alters Light-Induced Phase Shifts of the Circadian Activity Rhythm in Rats

ALCOHOLISM, Issue 7 2004
Yuhua Z. Farnell
Background: Developmental alcohol (EtOH) exposure produces long-term changes in the photic regulation of rat circadian behavior. Because entrainment of circadian rhythms to 24-hr light/dark cycles is mediated by phase shifting or resetting the clock mechanism, we examined whether developmental EtOH exposure also alters the phase-shifting effects of light pulses on the rat activity rhythm. Methods: Artificially reared Sprague-Dawley rat pups were exposed to EtOH (4.5 g/kg/day) or an isocaloric milk formula (gastrostomy control; GC) on postnatal days 4 to 9. At 2 months of age, rats from the EtOH, GC, and suckle control groups were housed individually, and wheel-running behavior was continuously recorded first in a 12-hr light/12-hr dark photoperiod for 10 to 14 days and thereafter in constant darkness (DD). Once the activity rhythm was observed to stably free-run in DD for at least 14 days, animals were exposed to a 15-min light pulse at either 2 or 10 hr after the onset of activity [i.e., circadian time (CT) 14 or 22, respectively], because light exposure at these times induces maximal phase delays or advances of the rat activity rhythm. Results: EtOH-treated rats were distinguished by robust increases in their phase-shifting responses to light. In the suckle control and GC groups, light pulses shifted the activity rhythm as expected, inducing phase delays of approximately 2 hr at CT 14 and advances of similar amplitude at CT 22. In contrast, the same light stimulus produced phase delays at CT 14 and advances at CT 22 of longer than 3 hr in EtOH-treated rats. The mean phase delay at CT 14 and advance at CT 22 in EtOH rats were significantly greater (p < 0.05) than the light-induced shifts observed in control animals. Conclusions: The data indicate that developmental EtOH exposure alters the phase-shifting responses of the rat activity rhythm to light. This finding, coupled with changes in the circadian period and light/dark entrainment observed in EtOH-treated rats, suggests that developmental EtOH exposure may permanently alter the clock mechanism in the suprachiasmatic nucleus and its regulation of circadian behavior. [source]

Crossing, Creolization, and the African Roots of American Culture

AMERICAN ANTHROPOLOGIST, Issue 3 2006
HARRIET JOSEPH OTTENHEIMER
Group Harmony: The Black Urban Roots of Rhythm and Blues. Stuart L. Goosman. Philadelphia: University of Pennsylvania Press, 2005. 291 pp. Right to Rock: The Black Rock Coalition and the Cultural Politics of Race. Maureen Mahon. Durham, NC: Duke University Press, 2004. 317 pp. Crossovers: Essays on Race, Music, and American Culture. John Szwed. Philadelphia: University of Pennsylvania Press, 2005. 283 pp. [source]

Reverse Electrical Remodeling of the Atria Post Cardioversion in Patients Who Remain in Sinus Rhythm Assessed by Signal Averaging of the P-Wave

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2007
NAGIB CHALFOUN M.D.
Objectives: This study was designed to determine whether the signal-averaged electrocardiogram of the P-wave (SAPW) is an independent predictor of recurrence of atrial fibrillation (AF) post cardioversion (CV), and to assess atrial remodeling using SAPW. Background: There are limited electrophysiologic data to predict the recurrence of AF post-CV. The electrical remodeling that occurs post-CV is poorly understood. Methods: Sixty-four patients with persistent AF undergoing CV were prospectively enrolled. SAPW parameters were measured the day of CV and repeated at 1 month. These SAPW parameters were compared to other baseline indices for the recurrence of AF. Results: Sixty patients (94%) had successful CV. At 1 month, 22 (37%) maintained sinus rhythm (SR). The SAPW total duration decreased significantly in those who remained in SR (159 ms ± 19 to 146 ms ± 17; P < 0.0001). Only the duration of AF (46 ± 50 days vs 147 ± 227 days, P = 0.03) and the presence of left ventricular hypertrophy (LVH, 12% vs 65%, P = 0.0006) were significantly associated with recurrence of AF. Atrial size strongly correlated with the SAPW duration in patients who remained in SR (R2= 0.67, P = 0.003) but not in those who returned to AF (R2= 0.11, P = 0.65). Conclusions: Atrial electrical reverse remodeling occurs in patients with AF who maintain SR post-CV. This remodeling is likely inversely related to the duration of AF and LVH. SAPW duration does not predict recurrence of AF post-CV. [source]

Inducible Atrioventricular Nodal Reentrant Echo Behind Organic 2:1 Infra-Hisian Block During Sinus Rhythm

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2006
CHIH-SHENG CHU
A 77-year-old male patient with an intermittent 2:1 infra-Hisian block during sinus rhythm was presented with dizziness and near-syncope. During electrophysiological (EP) study, dual atrioventricular (AV) nodal pathways and retrograde fast pathway were easily induced by atrial and ventricular programmed stimulation, respectively. A typical slow-fast AV nodal reentrant echo beat also could be demonstrated by single atrial extrastimulation. Atrioventricular nodal reentrant tachycardia (AVNRT) can occasionally exhibit 2:1 AV block. Conversely, AV nodal reentry property had been rarely reported behind 2:1 infra-Hisian block. The EP presentation from this case may support the notion that tissues below the His are not part of the reentrant circuit of AVNRT. [source]

High Density Endocardial Mapping of Shifts in the Site of Earliest Depolarization During Sinus Rhythm and Sinus Tachycardia

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4p1 2003
TIM R. BETTS
BETTS, T.R., et al.: High Density Endocardial Mapping of Shifts in the Site of Earliest Depolarization During Sinus Rhythm and Sinus Tachycardia.Previous mapping studies of sinus rhythm suggest faster rates arise from more cranial sites within the lateral right atrium. In the intact, beating heart, mapping has been limited to epicardial plaques or single endocardial catheters. The present study was designed to examine shifts in the site of the earliest endocardial depolarization during sinus rhythm and sinus tachycardia using high density activation mapping. Noncontact mapping of the right atrium during sinus rhythm was performed on ten anesthetized swine. Recordings were made during sinus rhythm, phenylephrine infusion, and isoproterenol infusion. The hearts were then excised and the histological sinus node identified. The mean minimum and maximum cycle lengths recorded were355 ± 43and717 ± 108 ms. A median of three (range two to five) sites of earliest endocardial depolarization were documented in each animal. With increasing heart rate the site of earliest endocardial depolarization remained stationary until a sudden shift in a cranial or caudal direction, often to sites beyond the histological sinoatrial node. The endocardial shift was unpredictable with considerable variation between animals; however, faster rates arose from more cranial sites(r = 0.46, P = 0.023). There was no difference in the mean cycle length of sinus rhythm originating from specific positions on the terminal crest(r = 0.44, P = 0.17). Cranial sites displayed a more diffuse pattern of early depolarization than caudal sites. In the porcine heart the relationship between heart rate and site of earliest endocardial depolarization shows considerable variation between individual animals. These findings may have implications for clinical mapping and ablation procedures. (PACE 2003; 26[Pt. I]:874,882) [source]

Ectopic Atrial Rhythm with Exit Block Following Catheter Ablation for Focal Atrial Tachycardias in a Patient with Prior Surgery for Atrial Septal Defect

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 6 2002
KIMIE OHKUBO
OHKUBO, K., et al.: Ectopic Atrial Rhythm with Exit Block Following Catheter Ablation for Focal Atrial Tachycardias in a Patient with Prior Surgery for Atrial Septal Defect. The patient was a 40-year-old woman with a history of surgery for atrial septal defect and catheter ablation for typical atrial flutter. An electrophysiological study was performed because she had palpitation and syncope. She had ectopic atrial rhythm originating from low lateral RA. Two focal atrial tachycardias ([1] superior vena cava-RA junction and [2] a low posteroseptal RA) were successfully ablated. Following catheter ablation for the second atrial tachycardia, she developed junctional rhythm because ectopic atrial rhythm showed exit block. However, atrial activation of junctional rhythm could conduct into the ectopic atrial rhythm focus and reset the rhythm when atrial activation of junctional rhythm reached the blocked line after atrial refractoriness by preceding ectopic atrial rhythm. [source]

Reversion and Maintenance of Sinus Rhythm in Patients with Permanent Atrial Fibrillation by Internal Cardioversion Followed by Biatrial Pacing

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 3 2002
NIKOLAOS FRAGAKIS
FRAGAKIS, N., et al.: Reversion and Maintenance of Sinus Rhythm in Patients with Permanent Atrial Fibrillation by Internal Cardioversion Followed by Biatrial Pacing. Patients in atrial fibrillation (AF) who fail external cardioversion are usually regarded as in permanent AF. Internal cardioversion may revert many such patients into sinus rhythm (SR) but the majority relapse rapidly into AF. We investigated whether internal cardioversion followed by biatrial pacing is an effective to restore and subsequently maintain SR in patients with permanent AF. Patients in permanent AF underwent internal cardioversion that was followed by biatrial temporary pacing for 48 hours. Those who remained in SR received a permanent biatrial pacemaker programmed to a rate responsive mode with a lower rate 90 beats/min. Primary end point of the study included maintenance in SR 3 months after internal cardioversion. Sixteen patients (14 men, 57 ± 11 years) were cardioverted. The median duration of AF was 24 months (quartiles, Q1= 8.5 and Q3= 102) and mean left atrium diameter was 48 ± 04 mm. A permanent biatrial pacemaker was implanted in 11 patients. At a mean follow-up of 15 months (range 4 to 24), 8 patients remained in SR for more than 3 months. AF was eliminated in 5 patients, while in two a second internal cardioversion on amiodarone was required. Antiarrhythmic therapy was used in half of our population and did not predict the long-term maintenance of SR. Following internal cardioversion with continuous biatrial pacing, 50% of patients with permanent AF were maintained for prolonged periods in SR. This is a new modality of treatment of permanent AF directed to the maintenance of SR that provides a further therapeutic option in end-stage AF. [source]

Assessment of Fetal Rhythm in Complete Congenital Heart Block by Magnetocardiography

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 6 2000
RONALD T. WAKAI
We report high precision assessment of fetal rhythm in utero in a case of isolated congenital complete heart block using fetal magnetocardiography. The recordings reveal a remarkably strong tendency for the atria and ventricles to synchronize, which is manifested by the continual presence of ventriculophasic sinus arrhythmia and frequent episodes of accrochage and isorhythmic AV dissociation. [source]

Presenting Rhythm in Sudden Deaths Temporally Proximate to Discharge of TASER Conducted Electrical Weapons

ACADEMIC EMERGENCY MEDICINE, Issue 8 2009
Charles D. Swerdlow MD
Abstract Objectives:, Sudden deaths proximate to use of conducted electrical weapons (CEWs) have been attributed to cardiac electrical stimulation. The rhythm in death caused by rapid, cardiac electrical stimulation usually is ventricular fibrillation (VF); electrical stimulation has not been reported to cause asystole or pulseless electrical activity (PEA). The authors studied the presenting rhythms in sudden deaths temporally proximate to use of TASER CEWs to estimate the likelihood that these deaths could be caused by cardiac electrical stimulation. Methods:, This was a retrospective review of CEW-associated, nontraumatic sudden deaths from 2001 to 2008. Emergency medical services (EMS), autopsy, and law enforcement reports were requested and analyzed. Subjects were included if they collapsed within 15 minutes of CEW discharge and the first cardiac arrest rhythm was reported. Results:, Records for 200 cases were received. The presenting rhythm was reported for 56 of 118 subjects who collapsed within 15 minutes (47%). The rhythm was VF in four subjects (7%; 95% confidence interval [CI] = 3% to 17%) and bradycardia-asystole or PEA in 52 subjects (93%; 95% CI = 83% to 97%). None of the eight subjects who collapsed during electrocardiogram (ECG) monitoring had VF. Only one subject (2%) collapsed immediately after CEW discharge. This was the only death typical of electrically induced VF (2%, 95% CI = 0% to 9%). An additional 4 subjects (7%) collapsed within 1 minute, and the remaining 51 subjects (91%) collapsed more than 1 minute later. The time from collapse to first recorded rhythm was 3 minutes or less in 35 subjects (62%) and 5 minutes or less in 43 subjects (77%). Conclusions:, In sudden deaths proximate to CEW discharge, immediate collapse is unusual, and VF is an uncommon VF presenting rhythm. Within study limitations, including selection bias and the possibility that VF terminated before the presenting rhythm was recorded, these data do not support electrically induced VF as a common mechanism of these sudden deaths. [source]

Wide QRS Tachycardia: What Is the Rhythm?

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 4 2006
Jonathan Rosman M.D.
We report a case of an elderly man who presented to the emergency room complaining of palpitations. Electrocardiogram revealed wide QRS tachycardia with a narrow beat within the tachycardia. Most commonly, a narrow complex beat during a wide complex tachycardia suggests a capture or fusion beat in the setting of ventricular tachycardia. However, there are situations where supraventricular tachycardia can also manifest this way. In our patient a pacemaker interrogation clarified the diagnosis. [source]

Magnesium Sulfate versus Placebo for Paroxysmal Atrial Fibrillation: A Randomized Clinical Trial

ACADEMIC EMERGENCY MEDICINE, Issue 4 2009
Kevin Chu MBBS
Abstract Objectives:, The objective was to investigate the efficacy of magnesium sulfate (MgSO4) in decreasing the ventricular rate in emergency department (ED) patients presenting with new-onset, rapid atrial fibrillation (AF). Methods:, A double-blinded, placebo-controlled randomized clinical trial was conducted in an adult university hospital. Patients aged ,18 years with AF onset of less than 48 hours and a sustained ventricular rate of >100 beats/min were randomized to either intravenous (IV) MgSO4 10 mmol or normal saline (NSal). Rhythm and instantaneous heart rate as measured by the monitor were recorded at baseline and every 15 minutes for 2 hours after starting the trial drug. Heart rate and rhythm were compared at 2 hours. A multilevel modeling analysis was performed to adjust for differences in baseline heart rate and any additional treatment and to examine changes in heart rate over time. Results:, Twenty-four patients were randomized to MgSO4 and 24 to NSal. Baseline heart rate was lower in the MgSO4 group (mean ± standard deviation [±SD] = 125 ± 24 vs. 140 ± 21 beats/min]. One and 3 patients in the MgSO4 and NSal groups, respectively, were given another antiarrhythmic or were electrically cardioverted within 2 hours after starting the trial drug. Heart rate (mean ± SD) at 2 hours in both MgSO4 (116 ± 30 beats/min) and NSal groups (114 ± 31 beats/min) decreased below their respective baseline levels. However, the rate of heart rate decrease across time did not differ between groups (p = 0.124). The proportion of patients who converted to sinus rhythm 2 hours post,trial drug did not differ (MgSO4 8.7% vs. NSal 25.0%, p = 0.25). Conclusions:, This study was unable to demonstrate a difference between IV MgSO4 10 mmol and saline placebo for reducing heart rate or conversion to sinus rhythm at 2 hours posttreatment in ED patients with AF of less than 48 hours duration. [source]

CPT-11 Alters the Circadian Rhythm of Dihydropyrimidine Dehydrogenase mRNA in Mouse Liver

CANCER SCIENCE, Issue 5 2001
Mikiko Shimizu
Combination chemotherapy consisting of 5-fluorouracil (5-FU) and 7-ethyl-10-[4-(l-piperidino)-l-piperidino]carboxycamptothecin (CPT-11) is a promising regimen for gastrointestinal cancer. The circadian-dependent efficacy and toxicity of 5-FU are related to the circadian variation in the activity of dihydropyrimidine dehydrogenase (DPD), which is a rate-limiting enzyme in the pyrimidine catabolic pathway. To optimize the schedule of the CPT-11 plus 5-FU combination, we investigated the effect of CPT-11 on the circadian rhythm of DPD in vivo. In control mice, the DPD mRNA level in the liver was significantly higher at 14:00 than that at 02:00. After intravenous administration of CPT-11 (30 mg/kg) at 20:00, the circadian rhythm of the DPD mRNA level in the liver was no longer observed 18 h later (14:00), but it was unaffected 6 and 18 h later (at 14:00 and 02:00) when CPT-11 was given at 08:00. In addition, a dose-dependent lengthening of the period of the circadian rhythm of DPD was observed for 42 h after intravenous injection of CPT-11 at 20:00. The levels of DPD protein and activity at 21 h after administration of CPT-11 (at 17:00) were significantly higher than at 9 h (at 05:00). These results suggest that CPT-11 may influence the circadian rhythm of DPD at the transcriptional level. Modulation of the circadian rhythm of DPD by CPT-11 may be a factor in optimizing the combination of 5-FU and CPT-11. [source]

The Differential Impacts of Early Physical and Sexual Abuse and Internalizing Problems on Daytime Cortisol Rhythm in School-Aged Children

CHILD DEVELOPMENT, Issue 1 2010
Dante Cicchetti
The impact of early physical and sexual abuse (EPA/SA) occurring in the first 5 years of life was investigated in relation to depressive and internalizing symptomatology and diurnal cortisol regulation. In a summer camp context, school-aged maltreated (n = 265) and nonmaltreated (n = 288) children provided morning and late afternoon saliva samples on 5 consecutive days. Child self-report and adult observer reports of child internalizing and depressive symptoms were obtained. Children experiencing EPA/SA and high depressive or internalizing symptoms uniquely exhibited an attenuated diurnal decrease in cortisol, indicative of neuroendocrine dysregulation. These results were specific to EPA/SA rather than later onset physical or sexual abuse or early occurring neglect or emotional maltreatment. [source]

Circadian Activity Rhythms and Mortality: The Study of Osteoporotic Fractures

JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 2 2010
Gregory J. Tranah PhD
OBJECTIVES: To determine whether circadian activity rhythms are associated with mortality in community-dwelling older women. DESIGN: Prospective study of mortality. SETTING: A cohort study of health and aging. PARTICIPANTS: Three thousand twenty-seven community-dwelling women from the Study of Osteoporotic Fractures cohort (mean age 84). MEASUREMENTS: Activity data were collected using wrist actigraphy for a minimum of three 24-hour periods, and circadian activity rhythms were computed. Parameters of interest included height of activity peak (amplitude), midline estimating statistic of rhythm (mesor), strength of activity rhythm (robustness), and time of peak activity (acrophase). Vital status, with cause of death adjudicated through death certificates, was prospectively ascertained. RESULTS: Over an average of 4.1 years of follow-up, there were 444 (14.7%) deaths. There was an inverse association between peak activity height and all-cause mortality rates, with higher mortality rates observed in the lowest activity quartile (hazard ratio (HR)=2.18, 95% confidence interval (CI)=1.63,2.92) than in the highest quartile after adjusting for age, clinic site, race, body mass index, cognitive function, exercise, instrumental activity of daily living impairments, depression, medications, alcohol, smoking, self-reported health status, married status, and comorbidities. A greater risk of mortality from all causes was observed for those in the lowest quartiles of mesor (HR=1.71, 95% CI=1.29,2.27) and rhythm robustness (HR=1.97, 95% CI=1.50,2.60) than for those in the highest quartiles. Greater mortality from cancer (HR=2.09, 95% CI=1.04,4.22) and stroke (HR=2.64, 95% CI=1.11,6.30) was observed for later peak activity (after 4:33 p.m.; >1.5 SD from mean) than for the mean peak range (2:50,4:33 p.m.). CONCLUSION: Older women with weak circadian activity rhythms have higher mortality risk. If confirmed in other cohorts, studies will be needed to test whether interventions (e.g., physical activity, bright light exposure) that regulate circadian activity rhythms will improve health outcomes in older adults. [source]

Effect of Light Treatment on Sleep and Circadian Rhythms in Demented Nursing Home Patients

JOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 2 2002
Sonia Ancoli-Israel PhD
First page of article [source]