bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Analysis of Post‐Pacing R‐R Intervals During Atrial Fibrillation
Authors: MORADY FRED , DICARLO LORENZO A. , KROL RYSZARD B. , DE BUITLEIR MICHAEL , BAERMAN JEFFERY M. 
Published: July 2006

Bursls of ventricular pacing at cycle lengths of 350–260 ms were introduced during atrial fibrillation in nine patients, and thepost‐pacing R‐R intervals were compared to the R‐R intervals of spontaneous QRS complexes. In eight of nine patients, the mean post‐pacing R‐R interval was 126–199 ms longer than the mean spontaneous R‐R interval (p < 0.005).Spontaneous runs of aberrantly conducted supraventricular complexes were recorded during atrial fibrillation in one patient. The meon R‐R interval following the runs of aberrantly conducted supraventricular complexes was significantly longer than the mean R‐R interval of spontaneous narrow QRS complexes (p < 0.001). but not significantly different than the mean post‐pacing R‐R interval.The findings of this study suggest that the R‐R interval that follows a wide‐complex tachycardia during atrial fibrillation is unlikely to be of value in differentiating ventricular tachycardia from aberrantly conducted supraventricular complexes. Analysis of R‐R intervals that follow bursts of ventricular pacing suggests that there is likely to be considerable overlap between the R‐R intervals that follow runs of ventricular tachycardia and the spontaneous R‐R intervals during atrial fibrillation. Furthermore, even when the post tachycardia R‐R interval clearly exceeds the longest spontaneous R‐R interval during atrial fibrillation, this is still of little diagnostic value, because a long pause may occur after either a run of ventricular tachycardia or a run of aberrantly conducted QRS complexes of supraventricular origin.
Time Course of Transvenous Pacemaker Stimulation Impedance, Capture Threshold, and Electrogram Amplitude
Authors: PLATIA EDWARD V. , BRINKER JEFFREY A. 
Published: July 2006

To examine the time course of atrial and ventricular stimulation impedance, capture threshold, and electrogram amplitude, we obtained noninvasive telemetric data in 63 patients who underwent implantation of unipolar, endocardial pacing leads and a second‐generation dual chamber pacemaker with expanded bidirectional telemetry, including stimulation impedance, endocardial electrograms, and automatic capture threshold determination. On follow‐up of 9–20 months [mean, 15 months], all but six patients continued to pace in the DDD mode. To validate measurements made with telemetry, invasive measurements made directly with a pacing system analyzer at time of implant were compared with immediate postimplant telemetric measurements. Significant correlation of acute stimulation impedance was noted in both atrial (r = .7, p < .001) and ventricular (r = .8, p < .001) lead systems. The atrial stimulation impedance decreased from 538 ohms at implant to 471 ohms at 13 months (p < .01); the ventricular stimulation impedance similarly declined from 545 ohms to 485 ohms at 13 months (p < .0l). Capture thresholds peaked at one month, then declined: atrial, 1.2 V at implant vs 2.2 V at 1 month (p < .008) and 1.4 V at 13 months; ventricular, 1.1 V at implant vs 1.9 V at 1 month (p < .001) and 1.3 V at 13 months. There were no significant changes noted in atrial or ventricular electrogram amplitude following implantation.We conclude that there is close correlation of invasive recordings with those made telemefrically with this pacemaker at time of implant. Chronic atrial and ventricular stimulation impedances gradually decline for at least one year following implant, while electrogram amplitude in both chambers remains unchanged. Atrial and ventricular capture thresholds increase within one month after implant and thereafter decline for at least one year, but not to implant levels. Expanded bidirectional telemetry with such second‐generation units allows more precise and efficacious long‐term appraisal of the pacemaker‐myocardium interface.
Comparative Efficacy of Continuous and Pulsed Argon Laser Ablation of Human Diseased Ventricle
Authors: CICCONE JOHN , SAKSENA SANJEEV , PANTOPOULOS DEMETRIS 
Published: July 2006

We compared the tissue lesions obtained in a saline medium using single continuous argon laser discharges with paired sequential continuous laser discharges in nine segments of diseased human ventricle resected from patients with and without ventricular tachycardia (VT) at cardiac surgery. Single continuous argon laser discharges were delivered to separate sites on the endocardial surface of the tissue segments for periods of 10, 20, and 30 seconds at laser beam power of 5 W (group IA) and 8 W (group IIA). Paired sequential argon laser discharges of 5, 10, and 15 seconds in duration were delivered to separate sites at a laser power of 5 W (group IB) and 8 W (group IIB). Gross and microscopic examination of each tissue lesion and its dimensions were performed.Laser irradiation of excised human ventricle resulted in a circular discrete burn at the site of application. Histologic examination showed crater formation due to tissue vaporization with the crater lining consisting of charred tissue and a zone of coagulation necrosis. Analysis of lesion dimensions in groups IA and IIA showed comparable lesion depth and diameter with single continuous and paired sequential laser discharges at energies of 50 J (p > .2), 100 J (p > .2), and 150 J (p > .2). Similarly, lesion depth and diameter were comparable in groups IB and IIB at the same energies. We conclude that paired sequential argon laser discharges may be used to produce comparable tissue lesions to single continuous argon laser discharges in diseased human ventricle.
Alternating Wenckebach Periods in Acute Inferior Myocardial Infarction: Clinical, Electrocardiographic, and Therapeutic Characterization
Authors: LEWIN RUBEN F. , KUSNIEC JAIRO , SCLAROVSKY SAMUEL , STRASBERG BORIS , ARDITTI ALEXANDER , PINCHAS AVRAHAM , AGMON JACOB 
Published: July 2006

We report on twelve patients with alternating Wenckebach periods (AWP) occurring during an acute inferior myocardial infarction (AIMI). There were nine males and three females, with a mean age of 61 years (range, 43 to 75). AWP appeared during the first 48 hours of the AIMI in 10 patients and on the fourth day of hospitalization in two patients. AWP occurred spontaneously in nine patients and following the administration of atropine in the remaining three patients. Mean systolic blood pressure significantly decreased during AWP as compared to the period preceding or following the bradyarrhythmia (93 ± 42 mmHg vs 123 ± 37 mmHg, p < 0.02). Killip functional class was significantly higher during AWP as compared to the period preceding or following the bradyarrhythmia (2.1 ± 1.2 vs 1.5 ± 0.8, p < 0.02). Pacemaker therapy was initiated prophylactically in two patients, because of syncope in six, because of hemodynamic deterioration in two, and for syncope and hemodynamic deterioration in two. Three patients died in cardiogenic shock despite pacemaker therapy. No evidence of right ventricular infarction was seen in the patients.Atropine administration during AWP significantly increased the sinus rate and significantly decreased the ventricular rates and the systolic blood pressure. In addition, three patients developed long bouts of paroxysmal AV block. Isoproterenol administration improved AV conduction in one patient, caused no change in two patients and induced non‐sustained ventricular tachycardia in three patients.In conclusion, AWP occurring during AIMI is a symptomatic bradyarrhythmia associated with hemodynamic deterioration. Drug therapy for this bradyarrhythmia is usually ineffective and sometimes paradoxical responses are observed. Pacemaker therapy is usually needed to correct symptoms and the worsening hemodynamic status. We recommend prophylactic pacemaker implantation in patients developing AWP during AIMI.
Hemodynamic Findings During Sinus Rhythm, Atrial and AV Sequential Pacing Compared to Ventricular Pacing In a Dog Model
Authors: ZHOU JIN‐TAI , YU GONG‐YUAN 
Published: July 2006

The hemodynamic responses of atrial lAF], atrioventricu‐lar sequential (AVP) and ventricuJar pacing (VP) were compared to sinus rhythm (SfiJ in seventeen anesthetized dogs with intact AV conduction. The atrium and/or ventricle were paced at fixed rates above the control sinus rate. An AV interval shorter than normal conduction was selected to capture the ventricle. The changes of pulmonary capillary wedge pressure (PCWP, mmHg). mean aortic pressure (MAP, mmHg), cardiac output (CO, L/min), systemic vascular resistance (SVR, dynes/s/cm−5), left ventricular stroke work index (SWI) and mean systolic ejection rate (MSER, ml/s) during sinus rhythm, atrial pacing and atrio‐ventricular sequential pacing (expressed in percentages of the individual values during ventricular pacing) were:

image
The importance of atrial systole for cardiac performance was clearly demonstrated in dogs with normally compliant hearts. In both atrial and atrioventricular sequential pacing compared to ventricular pacing there was a reduction of pulmonary capillary wedge pressure (PCWP) (p < 0.01) and systemic vascular resistance (SVR) (p < 0.01) despite an increase in cardiac output (CO). The lesser mean systolic ejection rate (MSER) found during atrioventricular sequential pacing compared to sinus rhythm and atrial pacing may be explained by the abnormal ventricular depolarization in this pacing mode; nevertheless, the mean systolic ejection rate was still greater than that found during ventricular pacing (p < 0.05).
Late Ventricular Potentials and Spontaneous and Induced Ventricular Arrhythmias in Dilated or Hypertrophic Cardiomyopathies. A Prospective Study About 83 Patients
Authors: FAUCHIER J.P. , COSNAY P. , MOQUET B. , BALLEH H. , ROUESNEL PH. 
Published: July 2006

In a series of 83 patients with dilated (DCM) (n = 56) or hypertrophic cardiomyopathies (HCM) (n = 27), were performed 24‐hour‐Holter monitorings, exercise stress testings, noninvasive recordings of late ventricular potentials (LVP), and programmed ventricular stimulations (PVS) (sinus rhythm and three cycles of stimulation, two extrastimuli, two right ventricle sites) (n = 53). in order to appreciate the frequency of ventricular premature depolarisations (VPDs), to correlate these results with myocardial vulnerability to TV induction, and to compare electrophysiologic and hemodynamic results. Holter monitoring showed that 80% of group A patients had VPDs (75% Lown's grade 3 or over) and 63% in group B (37%≥ grade 3). LVP were found in 15/56 DCM, and 2/27 HCM; in comparison with a control group of 32 normal subjects, the prevalence of LVP was only significant for DCM group. LVP were more frequent in cases of VPD's ≥ Lown's grade 3 at Holter monitoring in DCM group, (33% versus 7% if VPDs ≤ Lown's grade 3) and HCM group (20% versus 0) but the correlation was not significant. Exercise stress testing, conducted only in group E, revealed about 20% of VPDs. PVS provoked ventricular arrhythmia (>5 QRS) in 13 out of 33 cases in group A and in 2 out of 20 cases in group B. There was no significant correlation between the results of these methods of study and those of hemodynamic or echocardiographic explorations except for cardiac index in group A flower when LVP were present, and VPDs ≥ grade 3 during Holter) and end diastolic diameter (larger when PVS provoked fewer ventricular arrhythmias). In group B, PVS induced monomorphic VT in 2/3 patients with syncopes.Thus: (1) ventricular arrhythmias are frequent in cardiomyopathies but LVP had a significant prevalence only in dilated forms; (2) in DCM monomorphic induced VT reproduce spontaneous crisis, whereas in HCM it is possible to provoke VT in patients with syncopes but without this clinical arrhythmia; (3) in DCM as in HCM, ventricular arrhythmia can be independent from hemodynamic disorders.
Effects of Encainide on the Function of Implanted Pacemakers
Authors: SALEL ANTONE F. , SEAGREN SHIRLEY C. , POOL PETER E. 
Published: July 2006

The effect of encainide on chronic pacing thresholds was evaluated in 10 pafients, age 64–89, who were exposed to weekly increased encainide dosing (25 mg TID, 50 mg TID, 75 mg TID). Median pacing threshold (mujoules) increased modestly at each period compared to placebo and returned rapidly to baseline after discontinuation.
image

No patient experienced a pacing‐related ciinicai event. One patient had a large threshold increase (566%), but no failure to capture on 24‐hour ECG, and one patient whose threshold increased minimally had clinically insignificant capture failure, the longest event being 3 beats. No other failure to capture was noted. Thus, encainide, like a number of other antiarrhythmic drugs, appears to affect pacing thresholds. At the highest dose of 225 mg/day (75 mg TID, which exceeds the generally recommended dose of 50 mg TID), but not at lower doses, some patients may experience loss of capture that does not appear related to the change in threshold energy required. Increases in the duration of the paced QRS induced by encainide did not predict increases in threshold. Therefore, when higher doses of encainide are required in patients with pacemakers, clinical observation and ambulatory electrocardiographic monitoring should be carried out.
Comparison Between Two Versus Three Patches Single Pulse Shock Defibrillation in Pigs
Authors: MONTENERO ANNIBALE SANDRO , BOMBARDIERI GABRIELE , BARILARO CYNTHIA , DI FRANCESCO PALMIRO , BERTAZZONI STEFANO , SANTARELLI PIETRO , PISANÓ ENNIO , ALESSANDRINI FRANCESCO , POSSATI GIANFEDERICO 
Published: July 2006

The aim of the study was to test the hypothesis that defibrillation with a single pulse shock can be obtained at lower energy using three epicardial patches configuration (one cathode and two anodes) instead of the conventional two patches. The total surface area of the two‐ and three‐patches configuration was the same (10 cm2 vs 9.9 cm2). Epicardial spatial configuration was planned by using a computerized heart model. In ten anesthetized open‐chest pigs, ventricular fibrillation was induced by using AC current through the mesh plaque epicardial custom‐designed electrodes, and the minimum energy requirement for defibrillation was determined 15 seconds after the onset of stable ventricular fibrillation. Results were as follows (mean ± standard deviation):

image
Conclusions: three epicardial patches configuration significantly reduces energy requirements for defibrillation compared with two patches when single pulse shock is used.
The Effect of Biphasic Waveform Tilt in Transvenous Atrial Defibrillation
Authors: SRA JASBIR , BREMNER SIOBHAN , KRUM DAVID , DHALA ANWER , BLANCK ZALMEN , DESHPANDE SANJAY , BIEHL MICHAEL , LI HUAGI , JAZAYERI MOHAMMAD R. , AKHTAR MASOOD 
Published: July 2006

Atrial defibrillation can be accomplished using low energy shocks and transvenous catheters. The biphasic waveform tilt required to achieve optimal atrial defibrillation thresholds (ADFTs) is, however, not known. The effect of single capacitor biphasic waveform tilt modification on ADFT was assessed in 20 patients. Following AF induction the defibrillation pulses were delivered between the catheters positioned in the coronary sinus and the right atrium.The single capacitor biphasic waveform shocks, delivered over the same pathways, consisted of 65% tilt (65/65 biphasic waveform) to produce an overall tilt of 88%, or 50% tilt (50/50 biphasic waveform) to produce an overall tilt of 75%. Although 65/65 biphasic waveform delivers more energy, the shorter duration 50/50 biphasic waveform reduced stored energy ADFT 21%, from 1.34 ± 0.82 J with 65/65 biphasic to 2.06 ± 0.81 J. These differences were not statistically significant. Nine patients had lower ADFT with 50/50 biphasic waveform while five patients had lower ADFT with 65/65 biphasic waveform. Equivalent reduction in ADFT was seen in the remaining six patients. The ADFT was 0.83 ± 0.65 J when both tilts were considered. In conclusion, biphasic waveform tilt modification may affect the ADFT in an individual patient. The optimal biphasic waveform for ADFT is not known.
Myocardial Injury Induced by Radiofrequency and Low Energy Ablation: A Quantitative Study of CK Isoforms, CK‐MB, and Troponin‐T Concentrations
Authors: KATRITSIS DEMOSTHENES G. , HOSSEIN‐NIA MOJGAN , ANASTASAKIS ARIS , POLONIECKI JAN , HOLT DAVID W. , CAMM A. JOHN , WARD DAVID E. , ROWLAND EDWARD 
Published: July 2006

We conducted a prospective, controlled study to investigate the use of CK‐MB concentration and newer methods such as troponin‐T concentration and CK isoforms, in the assessment of myocardial damage caused by radiofrequency current or low energy DC catheter ablation. The study population consisted of 3 consecutive patients who underwent low energy catheter ablation, 28 consecutive patients subjected to radiofrequency ablation, and 4 patients wbo were subjected to radiofrequency energy ablation but also bad external DC shocks for cardioversion of atrial fibrillation that occurred during the procedure. The control group comprised eight subjects undergoing electrophysiological study. Prior to ablation and at 30 minutes, 1,2,6, and 12 hours following the procedure, serial blood samples were taken for measurement of troponin‐T and CK‐MB concentrations, and calculation of the MM3/MM1 and MB2/MB1 ratios.Troponin‐T concentration was raised above normal in all patients subjected to low energy ablation and in all but two patients subjected to radiofrequency ablation. Only 42% of all patients subjected to ablation had at least one raised CK‐MB concentration postablation. The MB2/MB1 ratio was raised in all but two patients following radiofrequency or low energy ablation but it was also abnormal in the preablation samples in nine patients. The MM3/MM1 ratio failed to detect myocardial damage in 71 % of all patients. There was a statistically significant difference between the control and patient groups regarding all four indices of myocardial damage. Low energy ablation caused a significantly higher degree of myocardial damage compared with radiofrequency (RF); this effect could not be attributed to different numbers of total energy discharges. Our results indicate that catheter ablation, regardless of the mode of energy used, inflicts detectable injury upon the myocardium. This injury can be quantitated by using newer analytical techniques, such as serial, postablation measurements of troponin‐T concentration.
Evolution of QRS Duration after Myocardial Infarction: Clinical Consequences
Authors: BREMBILLA‐PERROT BÉATRICE , HOURIEZ PIERRE , CLAUDON OLIVIER , PREISS JEAN‐PHILIPPE , DE LA CHAISE ARNAUD TERRIER 
Published: July 2006

The natural history of late potentials after acute myocardial infarction (AMI) has been studied in the first 2 years following myocardial infarction (MI). The purpose of the study was to assess the influence of some time delays since MI, including a time delay longer than 2 years on signal‐averaged ECG (SAECG). SAECG was recorded at 40‐Hz high pass filtering in 40 patients 10 days after acute MI (SAECG 1), then repeated 6–12 months later (mean 9 ± 3 months) (SAECG 2), and then, 2–4 years later (mean 3 ± 2 years) (SAECG 3). QRS duration, root mean square voltage of the last 40 ms of QRS (RMS 40), and low amplitude signal duration (LAS) were measured at the first (1), second (2), and third recording (3). Results: (***P < 0.001)The analysis of individual results showed a lengthening QRS duration at the third recording only in patients who had a decreased left ventricular ejection fraction (LVEF) at the third recording. In 12 patients with LVEF > 40%, QRS duration did not change at the first and third recording (104 ± 15 vs 101 ± 12 ms). In all 28 patients, but one with LVEF < 40%, QRS duration increased from 107 ± 12 to 128 ± 18 ms*. There was no correlation between QRS duration and LVEF at the second recording and no correlation between QRS duration increase at the third recording and the presence or not of late potentials at the first recording. QRS duration lengthening at the third recording was significantly correlated with a left ventricular (LV) dilatation occurrence at the two‐dimensional echocardiogram. All arrhythmic events, but two, occurred in patients who developed a QRS duration prolongation and were significantly correlated (P < 0.01) to a mean longer QRS duration (132 ± 20 ms) than in patients without arrhythmic events (113 ± 17 ms). In conclusion, the patients with a LV impairment, and who developed a LV dilatation several months after AMI, presented a delayed lengthening of QRS duration noted only at least 2 years after infarction. These patients are at risk of arrhythmic events.
Oxygen Uptake to Work Rate Relation Throughout Peak Exercise in Normal Subjects: Relevance for Rate Adaptive Pacemaker Programming
Authors: LEWALTER THORSTEN , RICKLI HANS , MACCARTER DEAN , SCHWARTZE PETER , SCHIMPF RAINER , SCHUMACHER BURGHARD , JUNG WERNER , CANDINAS RETO , LÜDERITZ BERNDT 
Published: July 2006

The oxygen uptake to work rate (VO2/WR) relationship observed throughout peak exercise testing is already being applied for rate adaptive pacemaker programming. However, the detailed curve design of VO2/WR with respect to the anaerobic threshold (AT) has not yet been investigated. It was the purpose of this study to determine the VO2/WR slope below and above the AT in a healthy control group. Seventy‐eight healthy control subjects (45.9 ± 17.4 years; 34 women: 49.9 ± 18.6 years 44 men: 43.6 ± 16.6 years) were exercised on a treadmill with “breath‐by‐breath” gas exchange monitoring using the symptom limited “ramping incremental treadmill exercise” (RITE) protocol. The slope of the VO2/WR relationship from rest to peak exercise (r‐p), rest to AT (slope A), and AT to peak exercise (slope B) in mL oxygen uptake per watt of external treadmill work was determined by linear regression analysis.The oxygen uptake to work rate relationship throughout peak exercise in the entire study group generated a significant slope change at the AT (31%, P < 0.0001) with a decreasing slope during higher work load intensities. Female subjects demonstrated a greater percentage of slope change at AT (43%), as compared to men (22%, P < 0.01). When using the oxygen uptake to work rate relationship for the programming of the pacemaker's rate response to exercise, the significant slope change at the AT should be considered to more appropriately pace during higher work intensities supported by anaerobic metabolism. Female pacemaker patients should be programmed to generate a steeper VO2/WR slope below AT with a greater slope change at AT, as compared to men. Abnormally high oxygen uptake to work rate ratios above the AT may be possibly used as an indicator of overpacing.
Life histories and distribution of British Trichoptera, excluding Limnephilidae and Hydroptilidae, based on the Rothamsted Insect Survey
Authors: Crichton M. I. , Fisher D. , Woiwod I. P. 
Published: July 2006

Catches of Trichoptera from 67 light traps in Great Britain are studied. Two families are excluded: the Limnephilidae because they have been considered in an earlier publication, and the Hydroptilidae.Catches from 148 complete year records, from 1965 to 1971, are grouped in three areas: A. Scotland, 15 sites; B. Wales and Northern England. 18 sites; C. Southern England, 34 sites. The total of over 146000 caddis flies includes 60 of the 109 British species from 14 families.Small or nil catches are explained by limited distribution or dispersal, short adult lives and day‐flying habits. The flight periods are related to published information on life cycles. Most species are univoltine, but some small species are bivoltine. In contrast to Limnephilidae, there is no evidence of a summer adult diapause, median weeks for flight periods tend to be earlier in the south, and few species are autumnal fliers. Density distribution maps, produced by computer, are given for six species.