bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experience with a New Epimyocardial Pacing Lead in Children
Authors: MICHALIK RICHARD E. , WILLIAMS WILLIS H. , ZORN‐CHELTON SUSAN , HATCHER CHARLES R. 
Published: July 2006

A new permanent epimyocardial Medtronic 4951 “stab‐in” or “fishhook” pacing electrode was implanted in 16 children. Identical technique, with particular attention to the direction of the coronary circulation, was utilized to implant the leads. There were 10 atrial implantations (5 active, 5 redundant) and 18 ventricular implantations (15 active, 3 redundant). Pacing modes were VVI (12), VDD (1), DVI (2), and DDD (1).Experience with the lead covers 280 patient months (3 days to 21.8 months, mean 14 months). Patients were allowed monthly via telephonic transmission. With the exception of the single patient who expired three days after implantation, each patient has returned for follow‐up analysis including chronic threshold determinations using the programming capabilities of the pulse generators. Only one lead required more than the minimum obtainable voltage output from the pulse generator to effect capture. No other lead required more than 5.0 volts at 0.5 ms pulse width. There have been no lead fractures or dislodgements.In this evaluation the Medtronic 4951 lead performed well in both atrium and ventricle in a group of children with diverse cardiac pathology. The small diameter of the lead and the low profile of the electrode are advantageous for use in pediatric patients.
Examination of an Exponential Model of Conduction Through the Human Atrioventricular Node *
Authors: DORVEAUX LILIANE , HEDDLE WILLIAM , JONES MICHAEL , TONKIN ANDREW 
Published: July 2006

The atrioventricular node (AVN) has been modeled by relating output (A2H2 or H1H2) to input (A1A2) where A and H are atrial and His bundle electrograms during fixed rate atrial pacing (A1A1) or with an extrastimulus (A2).
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This study examined this model in 61 nonselected patients, specifically for AVN (in)stability and the possibility of multiple pathways. After programmed atrial stimulation at two basic cycle lengths of 600 ms and 462 ms, A1H1, A2H2 and H1H2 were digitized and plotted as a function of A1A2, Seven of 104 trials were rejected as SD. A1H1 was >15 ms, suggesting AVN instability. Another 26 and 34 plots, respectively, of A2H2 and H1H2 were rejected because of inadequate data. In the remainder, goodness of fit of the single exponentials was tested statistically in three ways: R2, the runs test, and the Kendall rank coefficient test. Results were compared with an electrophysiologist who examined plots for one or more pathways (either discontinuous curves or slope change in a continuous curve). Single exponentials were successfully fitted (by runs test) in 44/71 and 34/63 of A2H2 and H1H2 plots, respectively, usually in accordance with the cardiologist. Discordance between computations and the cardiologist could be attributed to data scatter and lack of a sufficiently rigid stimulation protocol. The identification of bifurcation points in the presence of multiple pathways, particularly when manifest as a change in slope (approximately 6% of trials) rather than discontinuity of plots (approximately 20% of trials) remains an outstanding problem.
Changes in QT Interval during Exercise Testing in Patients with VVI Pacemakers
Authors: ODA EIJI 
Published: July 2006

. The changes in QT intervals were studied in nine patients with normal sinus node function who had VVI pacemakers. Though PP intervals uniformly shortened during exercise, the change in QaT* intervals during exercise was variable. The correlation between PP and QaT intervals varied from case to case. A good correlation was found in only two cases (r =+0.816 or +0.897); a fair correlation was found in four cases (r =+0.672, +0.615, +0.615, or −0.669) and in the remaining three, the correlation was poor (r =+0.494, +0.467 or−0.424). In patients who are candidates for VTI pacemaker implantation, changes in QaT intervals should be assessed during exercise stress testing to determine if the intervals shorten during exercise or not.(QaT*: Interval from the pacing spike to the apex of T‐wave.)
Transcutaneous Pacemaker Use in a Large Hospital
Authors: NOE ROBIN , COCKRELL WILLIAM , MOSES H. WESTON , DOVE JAMES T. , BATCHELDER JOHN E. 
Published: July 2006

For an eight‐month period temporary transcutaneous and transvenous pacemaker use was analyzed in a 602‐bed hospital which had readily available fluoroscopy. Twenty‐four patients were treated with transcutaneous pacemaker; 23 of these were treated for asystole during cardiac arrest. The only patient not suffering cardiac arrest could not tolerate the transcutaneous pacemaker because of pain. Two of these 23 patients were treated early in the arrest with successful resuscitation. They became conscious and were able to tolerate the pacemaker well. Most of the other patients were treated late in the arrest with little chance of any therapy being successful. Only four of these 21 patients were treated within 15 minutes of the onset of cardiac arrest. During the same time span, 23 patients received transvenous temporary pacemakers. Only four of this group had suffered cardiac arrest before pacing.We conclude that: (1) transcutaneous pacing can be successful but we did not find it useful when used late in a cardiac arrest; (2) transvenous pacing seemed the approach most often chosen for the non‐arrest situation.
Detection of Pathological Tachycardia by Analysis of Electrogram Morphology
Authors: DAVIES D. WYN , WAINWRIGHT RAY J. , TOOLEY MARK A. , LLOYD DAVID , NATHAN ANTHONY W. , SPURRELL ROWORTH A. J. , CAMM A. JOHN 
Published: July 2006

Pacemaker recognition of pathological tachycardia relies on heart rate analysis. This can lead to misdiagnosis when sinus tachycardia exceeds the preset tachycardia response trigger rate. We have explored a method for automatic tachycardia diagnosis by analysis of bipolar endocardial electrogram morphology.Electrograms were recorded from 11 patients (pts) during sinus rhythm and during a total of 20 abnormal rhythms: retrograde atrial depolarization from ventricular pacing in six patients; atrioventricular reentry tachycardia in five patients with intermittent left bundle branch block in one of those; AV nodal reentry tachycardia in five patients and ventricular tachycardia in three patients. Posture and respiration were varied during all rhythms except ventricular tachycardia. The electrograms were then digitized and converted to a form in which the amplitudes were proportional to the rates of change of the original electrogram (equivalent to a first time derivative); the derived signal was then analyzed by a new gradient pattern detection (GPD) program.Analysis of the processed atrial signals by GPD resulted in automatic recognition of abnormal rhythms from sinus rhythm in all cases except for one patient's retrograde atrial depolarization. At the ventricular level, GPD successfully distinguished all abnormal rhythms from sinus rhythm including recognition of left bundle branch block and varying degrees of preexcitation. Respiratory and postural variation did not affect the recognition process.We conclude that electrogram GPD has successfully and automatically detected a variety of arrhythmias which can be treated by implantable pulse generators and may, therefore, be a useful adjunct to heart rate analysis in future generations of such antitachycardia pacemakers.
Electrophysiologic Studies of Patients with Hypertrophic Cardiomyopathy Presenting with Syncope of Undetermined Etiology*
Authors: SCHIAVONE WILLIAM A. , MALONEY JAMES D. , LEVER HARRY M. , CASTLE LON W. , STERBA RICHARD , MORANT VICTOR 
Published: July 2006

Patients with hypertrophic cardiomyopathy (HC) have a high risk of sudden death. The best clinical predictors of sudden death from HC are young age, strong family history of sudden death, ventricular tachycardia (VT), and progression of symptoms such as syncope. We performed 24‐hour Holter monitoring and electrophysiologic studies (EPS) on 26 patients with HC, some with the obstructive form of the disease and some with syncope, in order to predict their vulnerabilily to syncope and to potentially malignant arrhythmias.Holter monitoring demonstrated supraventricular tachycardia [SVT] in 9/26 patients whereas atrial programmed electrical stimulation induced SVT in 17/26 patients. Of the 17 patients, nine had symptomatic hypotension with SVT while lying supine. Holter monitoring demonstrated nonsustained VT in 7/26 patients whereas ventricular programmed electrical stimulation induced VT or ventricular fibrillation (VF) in 6/26 patients. The patient who had the longest run of nonsustained VT on Holter had VF induced by ventricular programmed electrical stimulation. He was cardioverted to normal sinus rhythm with no untoward effects.We found that atrial programmed electrical stimulation induced SVT with hypotension best predicted a history of syncope in these patients. Although one patient required direct current cardioversion, EPS was conducted safely in all patients. Further long‐term studies are needed to demonstrate the value of clinical decisions based upon EPS in patients with HC.
Antitachycardia Pacing: A Comparison of Burst Overdrive, Self‐Searching and Adaptive Table Scanning Programs
Authors: HOLT P. , CRICK J.C.P. , SOWTON E. 
Published: July 2006

HOLT, P.Eight patients with the Siemens Elema “Tachylog” genera for implanted for management of paroxysmal reentrant tachycardia were studied to assess the safety and efficiency of three antitachycardia programs. The programs investigated were burst overdrive, self‐searching, and adaptive table scanning. There were five males and three females aged 19–62 years. Seven had Wolff‐Parkinson‐White syndrome, and one had dual atrioventricular nodal pathways. Four had right atrial electrodes and four had right ventricular electrodes. Patients were studied lying, standing, and exercising in all three modes, and the appropriate long‐term programs were chosen. The generator remained in a program for 1 month, if was interrogated and the memory was read, and then it was reprogrammed to a different antitachycardia mode. Burst overdrive was unsuitable for long‐term use in four patients, producing atrial fibrillation in one and ventricular arrhythmias in three. In this group, self‐searching and adaptive table scanning were safe and equally effective (mean number of attempts/tachycardia 6.97 and 6.3, respectively). In the four patients in whom all three programs could be used, burst overdrive proved to be most efficient, the mean number of attempts/tachycardia were 2.4 (cf 9.6 and 9.0 for self‐searching and adaptive table scanning). Thus, burst overdrive was only suitable for long‐term use in 50% of our patients, but when safe it was more efficient than the other two programs, especially in those with narrow termination windows on exercise.
Transesophageal Programmed Atrial Pacing as a Method of Selecting Patients with Sick Sinus Syndrome for Permanent Atrial Pacing
Authors: ŚWIĄTECKA GRAŻYNA , LUBIŃSKI ANDRZEJ , RACZAK GRZEGORZ , STANKE ANDRZEJ , JUZWA ALICJA , KUBICA JACEK 
Published: July 2006

Many recent studies have shown transesophageal programmed atrial pacing (TP) as a very practical, safe and convenient way for assessment of sinus node function and AV conduction. On the other hand, permanent atrial pacing is known to be superior to ventricular pacing due to arrhythmogenic and hemodynamic reasons. This is the reason why we decided to use TP as a method of choosing patients with sick sinus syndrome (SSS) for permanent atrial pacing. Sixty‐three patients with symptomatic (58) and asymptomatic (5) SSS in a variety of clinical situations were examined in this way. The following electrophysiological features were examined: sinus cycle length, sinus node recovery time as well as corrected time, secondary pause after overdrive stimulation, sinoatrial conduction time, Wenckebach point, induction of supraventricular arrhythmias by S1, S2, S3 programmed stimulation and burst pacing. Patients with abnormal parameters were examined once more after intravenous atropine 0.2 mg/kg to evaluate parasympathetic component. Standard 12‐lead ECG was performed in ail, and Holter monitoring in most of patients.Twenty‐six patients were candidates for permanent AAI pacing. Failures occurred in eight patients usually due to low P wave amplitude and electrode instability. Eighteen patients received AAI pacing systems: eight with brady‐tachycardia syndrome, nine with brady‐arrhythmia and one with sinoatrial block. In the follow‐up of 5–28 months in one patient occurred high degree AV block (11°) during digitalis therapy. Reduction of doses made this block disappear. Examination of Wenckebach point and possibility of inducation of supraventricular lachyarrhythmias in cases of atrial overexcitability are particularly useful in selecting patients for AAI pacing. (PACE, Vol 11 November Part II 1988)
Reliability of Minute Ventilation as a Parameter for Rate Responsive Pacing
Authors: LAU CHU PAK , ANTONIOU ANNA , WARD DAVID E. , CAMM A. JOHN 
Published: July 2006

A minute ventilation sensing rate responsive pacemaker was implanted in 11 patients with hradycardias. Their mean age was 59 ± 4 years (mean ± SEM). The pacemaker measures minute ventilation by sensing intravascular impedance using a standard bipolar electrode. The rate responsive programming was simple: apart from ascribing an upper and lower rate, the only programmable parameter was the slope of rate response. This could be derived approximately by assessing the suggested slope value during an exercise test in the ‘adaptive VVI’ mode. Compared with exercise in the VVI mode, symptom limited treadmill tests in the rate responsive mode showed a 33% improvement of exercise capacity and a 44% improvement of cardiac output as determined noninvasively by continuous wave Doppler measurements of the ascending aortic blood flow. The pacing rate was appropriately increased during a variety of daily activities such as walking at different speeds and gradients, and ascending and descending stairs. Voluntary interference of the respiratory pattern such as during coughing and hyperventilation increased the pacing rate from a resting rate of 70 bpm to 111 ± 10 and 86 ± 4 bpm respectively. Continuous talking during exercise attenuated the expected rate response. The pacemaker can sense activity induced by arm swinging.In conclusion, the Meta pacemaker improved cardiac output and exercise capacity in patients with bradycardias. Its rate response was related to workload. Although voluntary interference affected the pacing rate, excessive rate acceleration was not encountered.
Effect of Steroid Eluting Versus Conventional Electrodes on Propafenone Induced Rise in Chronic Ventricular Pacing Threshold
Authors: CORNACCHIA DANIELE , FABBRI MAURO , MARESTA ALEARDO , NIGRO PASQUALE , SORRENTINO FRANCESCO , PUGLISI ANDREA , RICCI RENATO , PERALDO CARLO , FAZZARI MASSIMO , PISTIS GIANFRANCO , SESTU PIERO , MEREU DIONIGI , De SETA FRANCESCO 
Published: July 2006

The aim of this study was to evaluate chronic ventricular pacing threshold increase after oral propafenone therapy. Eighty‐three patients affected by advanced atrioventricular hJock and sick sinus syndrome were studied at least 3 months after pacemaker implantation, before and after oral propafenone therapy (450–900 mg/day based on body weight). The patients were subdivided into three groups according to the type of unipolar electrode that was implanted: group I (41 patients)Medtronic CapSure 4003, group II(30 patients)Medtronic Target Tip 4011, and group III (12 patients)Osypka Vy screw‐in lead. In all cases a Medtronic unipolar pacemaker was implanted: 30 Minix, 23 Activitrax, 14 Elite, 12 Legend, and 4 Pasys. Propafenone biood level was measured in 75 patients 3–5 hours after propafenone administration. The pacing autothreshoid was measured at 0.8 V, 1.6 V, and 2.5 V by reducing puise width. At the three different outputs before and after propafenone, threshold increments were significantly lower in group I in comparison with group II and group III (propafenone ranging from < 0.001 to < 0.05). No significant difference was found in pacing impedance or in propafenone plasma concentration in the three groups. Strength‐duration curves were drawn for each group at baseline and after propafenone administration. Before propafenone, in group I, the knee was markedly shifted to the left and downward as compared to the classic curve, so that the steep part was predominant; in group II and group III this shift was progressively less evident. After propafenone we found the curve shifted to the right with the flat part progressively more evident in group II and group III as compared to group I. We conclude that steroid eiuting leads cause less threshold increase than conventionol and screw‐in ones after oral propafenone, thus leading to safer chronic pacing. Chronic pacing at 2.5‐V amplitude and 0.6‐msec width was feasible in 97% of group I patients and in 80% of group II patients, but not in group III due to an insufficient safety margin.propafenone, pacing threshold
Safety of High Energy Internal Cardioversion for Atrial Fibrillation
Authors: MANSOURATI JACQUES , LARLET JEAN‐MARIE , SALAUN GILLES , MAHEU BENOIT , BLANC JEAN‐JACQUES 
Published: July 2006

High energy internal cardioversion has been proposed as an alternative method to cardiovert drug refractory or external cardioversion refractory atrial fibrillation. However, the safety of this technique has not been clearly evaluated. We reviewed findings in 53 patients who underwent 55 sessions of high energy internal cardioversion (2 patients underwent 2 sessions] for termination of longstanding atrial fibrillation. Shocks energy varied from 70–270 J. Three patients had 3 shocks during the same session, 5 had 2, and 47 only 1. Success rate was 89% (success was defined as immediate conversion to normal sinus rhythm).Low cardiac output occurred in two patients, and resulted in the death of one of these individuals, a patient with significant hypertrophic cardiomyopathy and heart failure. The other patient recovered completely. In 11% of the cases, shock induced transient atrioventricular block, necessitating ventricular pacing until sinus rhythm was restored. In three patients, a moderate but asymptomatic and uncomplicated pericardial effusion was diagnosed on echocardiogram. Finally, four patients had side effects related to venous puncture, which resolved spontaneously. These results suggest that high energy internal cardioversion is effective for conversion of atrial fibrillation. However, the technique may not be optimal in patients with advanced hypertrophic cardiomyopathy and in such cases the technique should be used carefully and only in the case of failure of external cardioversion; no more than two shocks should be delivered during the same procedure. Temporary ventricular pacing should be provided in all patients and an echocardiogram should be performed before patients are being discharged.
Neutrophil‐Derived Oxidative Stress After Myocardial Ischemia Induced by Incremental Atrial Pacing
Authors: GIANNITSIS EVANGELOS , TETTENBORN IVO , WIEGAND UWE , POTRATZ JUERGEN , SHEIKHZADEH ABDOLHAMID , STIERLE ULRICH 
Published: July 2006

We studied the effect of atrial pacing‐induced myocardial ischemia on the generation of oxygen free radicals (OFR) in 8 patients with verified coronary artery disease (CAD) and in a control group of 4 patients without coronary atherosclerosis. Myocardial ischemia was measured metabolically by simultaneous lactate sampling from coronary sinus (CS) and arterial blood. Generation of OFR from purified viable polymorphonuclear neutrophils (PMN) was assessed by means of the chemiluminescence (CL) method. At peak pacing, 7 of 8 patients with CAD exhibited transient myocardial ischemia (mean lactate extraction ratio at rest: 23.6 ± 7.7 vs 5.21 ± 5.1 % at peak pacing, p= 0.012). In these patients, unstimulated PMN harvested from the CS depicted a significant increase of luminol‐enhanced CL (from 1.06 ± 0.54 to 2.15 ± 1.28 cpm x 105, p= 0.012) after atrial pacing. There was no additional effect from further ex vivo stimulation with phorbol myristate acetate.This finding underscores the role of myocardial ischemia as a potent endogenous activator of PMN function and may have implications in the pathogenesis and progression of atherosclerosis.
New Insight into Repolarization Abnormalities in Patients with Congenital Long QT Syndrome: the Increased Transmural Dispersion of Repoiarization
Authors: LUBINSKI ANDRZEJ , LEWICKA‐NOWAK EWA , KEMPA MACIEJ , BACZYNSKA ANNA M. , ROMANOWSKA ILONA , SWIATECKA GRAZYNA 
Published: July 2006

There is evidence from experimental studies that the time interval from the peak to the end of T‐wave reflects the transmural dispersion in repolarization (electrical gradient) between myocardial “layers” (epicardial, M‐cells, endocardial). Since Congenital Long QT Syndrome (LQTS) is considered to be classical disease or repolarisation abnormalities, we performed the present study to assess the transmtiral dispersion of repolarization in LQTS patients. The study group consisted of 17 patients: 7 LQTS pts and 10 pts from the control group. In each patient the 24‐hour ECG recording was performed on magnetic tape. The interval from the peak to the end of the T‐wave (TpTo) was automatically measured by Holter system during every hour as a measure of transmural dispersion of repolarisation. Thereafter the mean TpTo from 24‐hours was calculated. In addition the spatial QT dispersion was measured from 12 lead ECG and 3 channel Holter tape as a difference between the shortest and the longest QT interval between leads. The values were compared between groups using the Anova test.TpTo was 79,6±9,6 ms (72–92 ms) in LQTS group and 62,4±7,5 ms (51–70) in the control group (p< 0.001). In LQTS group TpTo was significantly longer at night hours 72,5±2 when compared to day hours 87,4±8 (p<0.01). The spatial QT dispersion was significantly higher in LQTS patients when compared to control, both in 12‐lead standard and Holter ECG.Congenital long QT syndrome is associated with increase in both transmural and spatial dispersion of repolarization. The extent of prolongation of the terminal portion of QT in patients with congenital long QT syndrome is greater at night sleep hours compared to daily activity.
A Relationship Between Fluctuations in Heart Rate and The Duration of Subsequent Episodes of Atrial Fibrillation
Authors: HNATKOVA KATERINA , WAKTARE JOHAN EP , SOPHER S MARK , MURGATROYD FRANCIS D , BAIYAN XIE , CAMM A JOHN , MALIK MAREK 
Published: July 2006

A relationship between autonomic tone and the onset of paroxysmal atrial fibrillation in some patients is recognised Episodes of PAF may vary enormously in duration, however, from a few beats to many hours. Whether autonomic tone influences the duration of ihe episodes has been less well investigated.From a database of Holter recording taken from patients with symptomatic PAF, we identified all episodes of at least 30 seconds duration which were preceded by noise free sinus rhythm. This study examined the heart rate prior to AF onset, the change in heart rate over the final minute of sinus rhythm and the time of AF onset, and compared the data from those episodes of AF of more than 5 minutes duration to the shorter ones. Heart rate was slower before long episodes of AF, but this was found to predominantly represent data from separate recordings. A highly significant rise in heart rate was detected prior to long AF episodes compared to shorter ones. Daytime AF episodes were slightly longer than nocturnal ones.The most important finding was that longer AF episodes were typified by a heart rate acceleration. This suggests that, regardless of underlying aetiology, and increase in sympathetic tone may be important in the sustenance of episodes of PAF.