bluuebunny/crossref_metadata_2025 huggingface dataset:
The Automatic Implantable Cardioverter/Defibrillator; Transesophageal Atrial Pacing Discloses the Potential for Erroneous Discharges
Authors: CRITELLI GIUSEPPE , MONDA VITTORIO , SCHERILLO MARINO , COLTORTI FERNANDO , GRECO CESARE , REALE ATTILIO
Published: July 2006

We report the occurrence of erroneous discharge from an implanted automatic cardioverter/defibrillator during transesophageal atrial pacing. Transesophageal pacing was performed as part of a study protocol on the inducibility of ventricular tachycardia from the atrium in patients with ischemic heart disease. At an induced heart rate of 166 beats per minute (a value just above the cut‐off rate of the device), the cardioverter/defibrillator was triggered. This observation suggests that transesophageal atrial pacing could be utilized to disclose the potential for spurious discharges in the event of fast atrial rhythms in patients with the automatic implantable cardioverter/defibrillator.
Complexity of AV Nodal Function: Complex Nodal Structure or Complex Behavior of Nodal Elements?
Authors: MALIK MAREK , CAMM A. JOHN
Published: July 2006

This paper discusses the hypothesis that the complex behavior of the atrioventricular (AV) node, with particular reference to Wenckebach periods, may be explained by the complexity of nodal structure and that complicated function of individual AV nodal fibers need not necessarily be considered. To prove this hypothesis, a computer model of cardiac excitation has been employed to simulate AV nodal function for two different anisotropic AV nodal model images. The experimental computer results show that the pattern of Wenckebach periods, and decremental and concealed AV nodal conduction can be explained without considering decremental conduction properties of individual AV nodal cells.
Symptomatic Sinus Node Dysfunction After Heart Transplantation
Authors: ZMYSUNSKI RONALD W. , WARNER MARY GRACE , DIETHRICH EDWARD B.
Published: July 2006

When donor hearts are studied systematically after transplantation, by programmed electrical stimulation, sinus node dysfunction has been found to be common though data regarding symptoms related to this phenomenon are not available. In this case report we describe a heart transplant recipient who experienced serious symptomatic sinus node dysfunction associated with transient atrial fibrillation 17 days after cardiac transplantation; there was no evidence of donor heart rejection, intracardiac electrophysiology testing confirmed sinus node dysfunction of the donor heart, but only with relatively rapid atrial pacing rates.
Radiofrequency Catheter Ablation of Refractory Ventricular Tachycardia
Authors: DAVIS MICHAEL J.E. , MURDOCK CHALLON
Published: July 2006

Transcatheter radiofrequency ablation of the arrhythmia focus was attempted in a 68‐year‐old patient with recurrent ventricular tachycardia, both spontaneous and inducible by programmed ventricular stimulation despite treatment with multiple antiarrhythmic drugs. The procedure was performed under local anesthetic without complication. The arrhythmia was not inducible immediately following ablation or 5 days later, and during 5 months follow‐up there has been no spontaneous recurrence.
Nonlinear Relationship Between Pacing and Evoked QT Intervals
Authors: BAIG M.W. , BOUTE W. , BEGEMANN M. , PERRINS EJ.
Published: July 2006

The paced evoked response is an established biosensor which has been used in the design of a rate responsive pacemaker. The unit is capable of sensing the interval between the delivery of a pacing stimulus and the downslope of the evoked T wave. With fixed rate pacing this interval has been shown to shorten with exercise and the main cause of this effect is thought to be mediated by the increase in the plasma catecholamines which are released on exertion. The detection of a reduction in the stimulus‐T interval results in an increase in pacing rate. The rate of change of pacing rate is re/erred to as the slope setting and this must be determined for each individual patient so that optimal rate responsive pacing can be effected. The algorithm underlying the slope setting is the pacing rate‐evoked QT interval relationship. This relationship was implemented as a linear function, but this study, which was conducted to reevaluate it, has demonstrated nonlinearity between the pacing and evoked QT intervals. The degree of QT shortening is least at low heart rates. This finding has resulted in the development of a new algorithm for the pacemaker in the form of a new program for the pacing system. This should result in a more physiological rate of change of heart rate with exercise and less chance of sudden changes in rate. These postulates are the subject of current clinical trials.
Concealed Atrial Parasystole Following the Senning Operation
Authors: YOUNG MING‐LON , ATKINS DIANNE L. , LLOYD THOMAS R. , WAGMAN ARMIN J.
Published: July 2006

A patient with sick sinus syndrome following the Senning operation was also found to have concealed atrial parasystole during intracardiac electrophysiological study. This atrial parasystolic pattern could he converted to atrial bigeminy by changing the atrial drive rate.
Physiological Principles of a New Method for Rate Responsive Pacing Using the Pre‐ejection Interval
Authors: CHIRIFE RAUL
Published: July 2006

The pre‐ejection interval (PEI) was measured in 30 patients during isotonic and isometric exercise, emotional stress, isoproterenol infusion, Valsalva maneuver, carotid massage, atropine injection and incremental pacing. In patients with complete AV block, the simultaneous atrial rate was used as a standard of comparison to assess the changes observed in PEI. The sensitivity, specificity, proportionality and speed of response were evaluated to determine the applicability of PEI for rate responsive pacing. PEI shortened promptly and proportionately to atrial cycle length with isotonic and isometric exercise, emotional stress, and isoproterenol (R values from 0.88 to 0.98, p < 0.001). It was neither affected by preload changes (Valsalva) nor by parasympathetic system (carotid massage and atropine). Incremental pacing had no effect in most of the patients but some showed a slight prolongation, similarly to what is observed with atrial cycle length. It is concluded that PEI is suitable for rate control in physiologically adaptive pacemakers.
Complete Atrioventricular Block Induced by Methyldopa
Authors: ROSEN BOAZ , OVSYSHCHER ILIYA A. , ZIMLICHMAN REUVEN
Published: July 2006

We present two patients who developed complete heart block due to treatment with methyldopa. After discontinuing methyldopa, conduction disturbances completely disappeared and recurred upon rechallenge with the medication. It is assumed that methyldopa can impair the myocardial conduction system by its central sympatholytic effect. Conduction anomalies should be excluded prior to treatment with methyldopa, and during treatment with the medication, the patients should be routinely screened for the presence of conduction anomalies.
Fast‐Slow Type of Atrioventricular Nodal Reentrant Tachycardia: Horizontal Dissociation of the AV Node During Tachycardia
Authors: FUJIKI AKIRA , YOSHIDA SHIGEKI , MIZUMAKI KOICHI , SASAYAMA SHIGETAKE
Published: July 2006

Two patients with recurrent supraventricular tachycardia are presented. The tachycardia was initiated and terminated by atrial extrastimulation beyond the atrial relative refractory period and the atrial activation sequence during the tachycardia was low to high. The induction of tachycardia was dependent on a critical AH interval. In patient 1 who had ventriculoatrial conduction, the tachycardia was initiated by the premature ventricular stimulation followed by double atrial response. In patient 2 the ventriculoatrial conduction was not observed. In both patients, the unchanged atrial cycle length during the tachycardia with antegrade Wenckebach AH block was observed. When AH block occurred during tachycardia the first AH interval was shorter than the subsequent HA interval. In patient 2 verapamil (5 mg) prolonged the atrial cycle length during tachycardia and rapid intravenous injection of adenosine triphosphate (10 mg) terminated the tachycardia. Oral diltiazem (280 mg/day) suppressed the tachycardia in patient 1. These findings suggest that the mechanism of tachycardia may be fast‐slow type of AV nodal reentry in the upper portion of the AV node and this type of arrhythmia has tendency to show incessant form.
Identification of Ventricular Tachycardia Using Intracavitary Ventricular Electrograms: Analysis of Time and Frequency Domain Patterns
Authors: LIN DONGPING , DICARLO LORENZO A. , JENKINS JANICE M.
Published: July 2006

Tachycardia detection by implantable antitachycardia devices using rate alone has major limitations. Several alternative methods have been proposed to distinguish ventricular tachycardia or ventricular fibrillation from normal sinus rhythm using intracardiac electrograms. These methods have not been tested, however, for recognition of ventricular tachycardia in patients with abnormal surface QRS conduction during sinus rhythm or with antiarrhythmic drug therapy. In this study, three techniques for the indentification of ventricular tachycardia from intracavitary bipolar ventricular electrograms were examined and compared: correlation waveform analysis, amplitude distribution analysis, and spectral analysis using Fast Fourier transformation. Thirty episodes of induced monomorphic ventricular tachycardia were analyzed and compared sinus rhythm in four groups of patients with: I. Normal surface QRS conduction during sinus rhythm without antiarrhythmic drug therapy (five episodes); II. Intraventricular conduction delay or bundle branch block during sinus rhythm without antiarrhythmic drug therapy (nine episodes); III. Normal surface QRS conduction during sinus rhythm with antiarrhythmic therapy (six episodes); and IV. Intraventricular conduction delay or bundle branch block during sinus rhythm with antiarrhythmic drug therapy (ten episodes). Correlation waveform analysis had 100% sensitivity and specificity in distinguishing ventricular tachycardia from sinus rhythm, even in the presence of an intraventricular conduction delay, bundle branch block, and antiarrhythmic drug therapy. In contrast, amplitude distribution analysis differentiated 15/30 episodes (50.0%) of ventricular tachycardia from sinus rhythm, and a maximum of 18/30 episodes (60.0%) of ventricular tachycardia were identified by specal analysis using Fast Fourier transformation. Correlation waveform analysis appears to be a reliable technique to discriminate ventricular tachycardia from sinus rhythm using intracavitary ventricular electrograms. Its computational demands are modest, making it suitable for consideration in an implantable antitachycardia device.
Effects of Extracorporeal Shock Wave Lithotripsy on Cardiac Pacemakers and its Safety in Patients with Implanted Cardiac Pacemakers
Authors: COOPER DANIEL , WILKOFF BRUCE , MASTERSON MARTIN , CASTLE LON , BELCO KAREN , SIMMONS TONY , MORANT VICTOR , STREEM STEVAN , MALONEY JAMES
Published: July 2006

Ejects of extracorporeal shockwave lithotripsy (ESWL) were studied on 15 pacemakers (standard single chamber n = 5, dual chamber n = 6, rate responsive single chamber [Activitrax] n = 4). In‐vitro testing involved suspending the pacemakers in a bath of degassified, deionized water firmly taped to a platform at the point of maximal pressure, i.e., second focal point (F2), where they received pressure shocks (x̄= 1300) from the HM3 Dornier lithotriptor. The pacemakers, programmed to their most sensitive setting, were continuously pacing at nominal outputs (atria) and ventricular pacing in the DDD mode). All units were assessed by a pacing system analyzer before and after the study, then underwent destructive analysis. During standard single chamber pacing (VVI) the pacing stimulus triggered ESWL. For dual chamber devices, ESWL was triggered by the atrial paced event which induced inhibition of the ventricular output in two pacemaker. This was eliminated by reprogramming to a less sensitive setting. The pacemaker can, hermetic seal and internal circuitry were undamaged in all units. Two rate responsive single chamber pacemakers had their activity sensing piezoelectric elements shattered when placed at F2. Two other units placed 5 cm from F2 were stimulated to their maximum upper programmed pacing rate with ESWL therapy, but were otherwise unaffected. Subsequent to this study, six patients with pacemakers programmed to the VVI (five), DDD (one) modes implanted in the thorax underwent successful ESWL without pacemaker or arrhythmic event. Conclusions: (A) It is generally safe for patients implanted with standard single chamber devices in a ventricular application to undergo ESWL without modifying the pacing/sensing parameters. (B) Patients implanted with dual chamber devices who pace in the atrium should be reprogrammed to the VVI mode during ESWL. (C) Patients with piezoelectric activity sensing rate responsive single chamber pacemakers should have this feature programmed off during ESWL and, if implanted in the abdomen, probably should not undergo ESWL.
Heart Rate Monitoring in Implanted Pacemakers
Authors: BEGEMANN MALCOLM J.S. , BOUTE WIM
Published: July 2006

Increasing pacemaker memory allows integration of heart rate monitoring into the pacemaker. Two main methods can be distinguished. 1. Heart rate monitoring in histograms. 2. Heart rate monitoring in the time domain (heart rate holter). Method 1 is useful in antitachycardia and diagnostic pacemakers when short specific events must be detected (tachycadia, bradycardia). For the analysis of a rate adaptive pacemaker this method is less appropriate as it does not give any information about the dynamics of rate changes or its time relations. For this purpose Method 2 will give more information about the functioning of the pacemaker as it does not only store the heart rate but also the timing of the heart rate so that changes in heart rate can be correlated to the activity of the patient. An algorithm was developed to store the average heart rate over 7.8 minute periods in a pacemaker. On interrogation of the pacemaker the information will always reveal the heart rate over the 24 hours prior to interrogation. This monitor can also be temporarily programmed to store the average heart rate in 20 second intervals to monitor the response to an exercise test for a period of 1 hour. The time needed for a standand follow‐up procedure of a rate adaptive pacemaker can be dramatically reduced to a value close to the follow‐up time of a standard WI pacemaker.
A New Algorithm for a High Level of Protection Against Pacemaker‐Mediated Tachycardia
Authors: LAMAISON DOMINIQUE , GIRODO SILVIE , LIMOUSIN MARCEL
Published: July 2006

Pacemaker‐mediated tachycardia (PMT) is a well‐known complication of DDD pacing. PMT needs a permeable V‐A conduction and is usually initiated by a premature ventricular or atrial systole, artifact sensing, or misprogramming (long AV delay [AVD]). Today, protection against PMT is expected from pacemaker multiprogrammability. Unfortunately, this prevention is often ineffective; postventricular atrial refractory period (PVARP) must be prolonged, which limits the upper tracking rate and the patient capacity. The new Chorus ELA Medical DDD pacemaker provides classic protection against PMT (PVARP prolongation after premature V or A complex, magnet application, noise sensing), hut also automatically reduces an eventual PMT and adjusts AVD or PVARP for a high level of protection. The process is divided in four steps: (1) a sensing step for 16 cycles, with V‐P conduction analysis; (2) confirmation of the presence of the PMT and analysis of V‐A conduction time; (3) a termination step, by extending the PVARP after the following ventricular heart beat; and (4) in case of immediate recurrence of the tachycardia, reprogramming of the AVD and eventually of the PVARP. By first reducing AVD, before reprogramming PVARP, the pacemaker preserves point 2:1, providing a higher exercise capacity. This algorithm was successfully tested in three patients who had a permeable V‐A conduction, without any adverse effect.
Clinical Experience with Steroid‐Eluting Unipolar Electrodes
Authors: PIRZADA FAROUK A. , MOSCHITTO LAWRENCE J. , DIORIO DEBORAH
Published: July 2006

In continuing search of low chronic threshold leads, a new concept of electrode design which is capable of delivering corticosteroids at the myocardial tissue interface has been made available by Medtronic. Twenty‐three patients, 17 females and 6 males, were either implanted with 4003 (n = 21) or 5023 (n ‐ 2) steroid‐eluting electrodes in the ventricular chamber. Pacing modes utilized were WIM (n = 13) or DDD (n = 10). Pulse generators used were Medtronic (7005. 8317, 8329) Pacesetter (285) and Intermedics (283). Thresholds at the time of implantation at 0.50 msec pulse width were 0.40 ± 0.02 volts at 0.66 ± 0.05 milliamps. Resistance and R wave measured were 565.43 ± 22.07 ohms and 9.24 ± 1.06 mv, respectively. Chronic thresholds were checked on routine follow‐up visits by either decreasing pulse width and for pulse amplitude. Data is being reported between 1 and 88 (23.22 ± 4.35) weeks. Pulse width threshold at 2.5 volts were 0.10 msec (n = n) and 0.05 msec or lower (n = 12). At 5.0 volts no loss of capture was seen at 0.05 msec (n = 22) except in one patient at 0.10 msec. Pulse width thresholds in the first 24 weeks were lower than 0.20 msec at 2.5 volts (n = 15) and less than 0.70 msec, at 0.8 volts (n = 6). No loss of sensing was seen by electrocardiographic analysis at the time of threshold checks with the pulse generator at standard setting of the R wave. Thus, in this initial report, the steroid‐eluting electrodes have demonstrated very low thresholds both in the early and chronic follow‐up phase. Demonstration of consistently low thresholds, avoiding initial peaking, will permit routine low output setting without compromising safety and thus prolong the life of the pulse generators.
Preliminary Studies on a New Steroid Eluting Epicardial Electrode
Authors: STOKES KENNETH BLAINE
Published: July 2006

Acute and chronic canine atrial and ventricular thresholds and sensing were compared for a steroid eluting epicardial plaque electrode, a similar steroid free plaque electrode and two standard leads. The steroid eluting electrode had low, stable thresbolds in atrium and ventricle compared to the steroid free plaque and standard leads. This new electrode also provided improved atrial sensing. Thus, the concept of a steroid eluting epicardial electrode shows promise for further evaluation.
Initial Clinical Experience with a Minute Ventilation Sensing Rate Modulated Pacemaker: Improvements in Exercise Capacity and Symptomatology
Authors: LAU CHU‐PAK , ANTONIOU ANNA , WARD DAVID E. , CAMM A. JOHN
Published: July 2006

A minute ventilation sensing rate modulated pacemaker was implanted in nine patients with bradycardia. Minute ventilation is sensed in this pacemaker by means of a standard bipolar pacing electrode. Compared with exercise in the constant rate ventricular pacing (WI) mode at 1 month after pacemaker implantation, rate responsive pacing resulted in an improvement of exercise capacity of 33 ± 5% (from 437 ± 42 s in the WI mode to 593 ±57 s in the rate modulated mode, P < 0.01, Bruce protocol). This improvement was maintained in the seven patients in whom an exercise test was repeated at 3 months after implantation. The pacing rate was significantly correlated with oxygen consumption (r = 0.8A ± 0.04) and measured minute ventilation (r = 0.76 ± 0.06), Symptomatology in these patients was assessed by means of self‐assessment questionnaires in a double blind, randomized cross‐over study in which the pacemaker was alternatively programmed into the WI and rate modulated modes. Significant improvements in “shortness of breath” and “energy during daily activities” were documented during rate modulated pacing and “palpitations” and “chest pain” were not worsened. Most patients preferred the rate modulated mode during the study. In conclusion, rate modulated pacing by sensing minute ventilation resulted in better exercise capacity and symptomatology. The pacing rate also showed good correlation with the individual's oxygen requirement.
Single Versus Double Chamber Rate Responsive Cardiac Pacing: Comparison by Cardiopulmonary Noninvasive Exercise Testing
Authors: VOGT P. , GOY J. J. , KUHN M. , LEUENBERGER P. , KAPPENBERGER L.
Published: July 2006

A new double chamber rate responsive cardiac pacemaker (DDDMR) bas been implanted in seven patients (four males and three females) with a mean age of 62 years. Indication for pacemaker treatment was complete AV block in two patients, complete AV block associated to sinus node disease in three patients and sinus node disease alone in two patients. Six patients underwent two maximal stress tests on a cycloergometer performed twice randomly starting with WIMR or DDDMR. Basic work load of 50 watts was increased by steps of 25 watts every 2 minutes. Heart rate, respiratory frequency, blood pressure, exercise duration, maximal charge developed, oxygen consumption, rate pressure product, efficiency and Borg scale were compared. Our results show a general trend but no significant differences between ail the measured parameters except for efficiency which was significantly higher with DDDMR. These results prove a slight improvement of cardiopulmonary performance in DDDMR pacing compared to WIMR and also confirm the importance of atrial contribution to cardiac output on exercise.
Pediatric Transvenous Pacing: A Concern for Venous Thrombosis?
Authors: GILLETTE PAUL C. , ZEIGLER VICKI , BRADHAM GILBERT B. , KINSELLA PAUL
Published: July 2006

Transvenous pacing has become the preferred method of pediatric cardiac pacing. Although no clinically important venous thromboses have been reported, concern has arisen about occult venous thrombosis. We evaluated 19 randomly selected children who had transvenous pacing implants. Sixteen were evaluated by venous plethysmography and Doppler while three had venous angiography and one had both. The leads had all been inserted by subclavian vein puncture. Ages at time of implant ranged from 17 months to 25 years; mean 9.8 years, median 9.0 years. Implant weights were from 9.6 kg to 56.0 kg, mean 31 kg, median 31 kg. The interval from implant to time of procedure ranged from 1 month to 46 months, mean 22.5 months, median 24 months. Four patients had one lead while 14 had two and one had four. Eleven leads were unipolar and 25 were bipolar. The bipolar leads were 6.6 French diameter. In the 19 patients evaluated, no thromboses were detected nor any narrowing greater thant 10% of proximal diameter as seen by angiography. No disturbances of blood flow in the subclavian vein was noted. Transvenous pacing did not result in venous flow abnormalities in these pediatric patients.
Pacemaker Implantation in Children: A 21‐Year Experience
Authors: WALSH CHRISTINE A. , McALISTER HUGH F. , ANDREWS CAROLYN A. , STEEG CARL N. , EISENBERG ROBERT , FURMAN SEYMOUR
Published: July 2006

Forty‐one children, 20 hoys and 21 girls, aged 11 days to 19 years (mean 9.9 years) at initial pacemaker implant, were followed 1 to 248 months (mean 90 months). Ten (mean age 8.2 years) were implanted between 1966 and 1972 (Group I), 14 (mean age 9.9 years) between 1973 and 1980 (Group 11) and 17 (mean age 10.9 years) from 1981 through April 1988 (Group 111). Arrhythmias were congenital complete heart block in 19, postoperative heart block in 15, acquired heart block in 3, sick sinus syndrome in 3, and bradycardia‐induced ventricular fibrillation in 1. Twenty‐eight of 41 children had a transvenous implant: 40% of Group I, 71% of Group 11 and 82% of Group III. Thirteen were cephalic, four subclavian and 11 jugular. Generator site was pectoral in 19, abdominal in 12, intrathoracic in one, and retromammary in nine of 12 girls aged 10 years or more at implant. In Groups 1,11 and 111, 5, 14 and 6 had VOO or WI units; 5, 0 and 8 dual chamber (VAT, VDD and DDD) pacemakers; 0, 0 and 1 AAI; and 0, 0 and 2 rate‐modulated (WIR) units at initial implant. The average interval between pacer‐related hospitalizations in Groups I, II and III was 20, 42, and 39 months. Complications included infection in six, hemothorax in one, and impending pacemaker erosion in one. Six patients died, one of pacer infection, four from primary cardiac disease, and one suddenly without apparent reason. Follow‐up continues in 31: 14 are employed full‐time, three are homemakers, eight are full‐time students, and six are active pre‐schoolers. Four women have had normal children. We conclude: (1) children with implanted pacemakers can have a normal lifestyle, with prognosis based on underlying cardiac disease; (2) elective epicardial electrodes are now rarely needed; (3) implantation via the cephalic vein is feasible and complication‐free; (4) retromammary implant is technically easy and cosmetic; (5) dual chamber and rate‐modulated pacemakers can be utilized effectively.(PACE, Vol. 11 November Part II 1988)
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.
Efficacy and Safety of Low Doses of Beta‐Blocker Agents Combined with Amiodarone in Refractory Ventricular Tachycardia
Authors: TONET J. , FRANK R. , FONTAINE G. , GROSGOGEAT Y.
Published: July 2006

Twenty patients aged 55 ± 16 years with 40 chronic ventricular tachycardias (VT) refractory to 4.6 ± 1.9 antiarrhythmic drugs, used alone or in combination, were managed by low doses of beta‐blocker agents combined with oral amiodarone (Am), either after loading (1.2 g for 7 days, n: 5) or reloading (1.2 g for 4 days, n: 15) of Am. All patients proved refractory to Am alone. Seven VT were also refractory to endocardial catheter fulguration in six patients. Thirteen patients had coronary artery disease, three had arrhythmogenic right ventricular dysplasia, two had dilated cardiomyopathy, one had valvular disease, and one had no structural heart disease. Ten patients had an EF <30%. Ten patients were in NYHA functional class three. VT was permanent in three patients, daily in three, weekly in seven, paroxysmal in seven. In 11 patients, VT occurred both at day and night. In 11 patients, decrease of the sinus cycle preceeded VT. Oral administration of a daily low dose of a beta blocker agent (acebutolol 100 mg, betaxolol 5–10 mg, metoprolol 50 mg, nadolol 20–40 mg, pindolol 2.5 mg, propanolol 30 mg, sotalol 80–160 mg, terta‐tolol 2.5 mg) combined with 400 mg/day of Am suppressed VT episodes in all patients. None presented heart failure or collapse. The mean reduction of the heart rate was 15% (65 to 55/min). At discharge, exercise ECG (n: 14) induced non sustained VT in two patients. At programmed electrical stimulation (PES) (n: 15), VT was no longer inducible in 4 patients, was slower, well‐tolerated in nine patients, and remained inducible at the same rate in only two patients. Chronic treatment prevents recurrence of VT in 19 patients during a follow‐up of 14 ± 9 months (range 2 to 33). Conclusions: (1) beta blockers agents and Am have strong synergistic effects; (2) antiarrhythmic treatment with low doses of beta blockers could be managed by PES; (3) at the doses used in (his study, all beta blockers presented the same safety; (4) combination of low doses of beta blockers agents with chronic Am therapy inhibit VT.
Automatic External Defibrillation of Patients After Myocardial Infarction by Family Members: Practical Aspects and Psychological Impact of Training
Authors: MCDANIEL CHRISTINE M. , BERRY VIRGINIA A. , HAINES DAVID E. , DIMARCO JOHN P.
Published: July 2006

Automatic external defibrillation (AED) offers the potential for minimally trained individuals to convert life‐threatening ventricular arrhythmias prior to arrival of emergency rescue personnel but optimum usage of AED remains undefined. To test the practical aspects of home AED in high risk patients after myocardial infarction, we identified 40 consecutive high risk post‐MI patients, who satisfied inclusion and exclusion criteria. Fifteen (38%) patients were eliminated at their physician's request and nine others refused to participate. Twenty‐six family members of the remaining 16 patients were trained in AED with follow‐up testing at 3 months. Level of skill, especially in CPR performance, declined to unsatisfactory levels in 35% of trainees, including all over age 55. Trainees felt more confident due to availability of AED and 90% felt no strain in intrapersonal relationships. Psychological testing revealed a decrease in patient and trainee depression scores and no change in anxiety or obsessiveness during the study. These observations suggest the following: (1) better awareness of benefits of AED by physicians and lay persons is necessary, (2) retraining at <3 month intervals will be required for many spouse trainees and (3) there are no common adverse psychologic sequelae to training in AED.
Perspectives on Clinical Decision‐Making: The Application of Pattern Analysis
Authors: KNOEBEL SUZANNE B.
Published: July 2006

It is the thesis of this presentation that more precise diagnoses and prognostications result when clinical information is analyzed as data‐sets or patterns rather than collections of discrete data. Two examples are given in support of the thesis: the classification by computer of QRS complexes in the ambulatory electrocardiogram and the prediction of risk for recurrent ventricular tachycardia. The advantages to he gained from pattern analysis are: (1) significant variables are not preselected and the data are, therefore, unbiased, and (2) nuances in clinical patterns become evident when patients are presented as data‐sets. It is proposed that competent physicians undoubtedly use pattern analysis in their decision‐making and that expert systems designed to simulate physician behavior might be more accurate if based in pattern analysis.
Cost‐Effective Management of Patients Following Myocardial Infarction: the Impact of Ischemia on Alternative Approaches
Authors: DITTUS ROBERT S. , ROBERTS STEPHEN D. , ADOLPH J. , KNOEBEL SUZANNE B.
Published: July 2006

Following uncomplicated myocardial infarction patients are at varying risk for cardiovascular morbidity and mortality. In order to identify and treat high risk patients, various management approaches can be employed. We performed a decision analysis to examine the cost‐effectiveness of seven alternative strategies under the assumption that prognosis is affected by both the location of anatomic obstruction and the degree of myocardial ischemia. Strategies included combinations of angiography and two theoretical diagnostic tests capable of detecting ischemia with different degrees of accuracy. The strategy associated with the lowest overall six month mortality initiated testing with the diagnostic test most sensitive for ischemia, slightly better than proceeding initially to angiography. Initial use of a test sensitive for ischemia was also considerably more cost‐effective than proceeding directly to angiography. Future analyses evaluating the role of diagnostic tests in coronary artery disease should incorporate the dimension of ischemia.
Computer Modeling of Cardiac Rhythm Disturbances and Heart‐Pacemaker Interaction
Authors: MALIK MAREK , CAMM A. JOHN
Published: July 2006

Different computer models have been developed in order to study various aspects of cardiac electrophysiological processes. These models can be classified according to many parameters and also in respect to their application areas. One group of the models is devoted to computer simulation of cardiac rhythm disturbances and to reproduction of interactions between the heart and an artificial pulse generator. This report overviews the recent models of arrhythmias and heart‐pacemaker interaction. Special attention is paid to (1) functioning of fundamental model elements, (2) structure of the heart model, (3) pacemaker models, and (4) forms of results offered by simulation experiments. Existing models are classified and compared. To illustrate the medical capability of rhythm and pacemaker models, three computational experiments are presented with model atrioventricular reentry tachycardia and reentry tachycardia mediated by a DDD pacemaker. Future development and utilization of arrhythmia and pacemaker models are briefly discussed.
Modern Pacemakers: Implantable Artificial Intelligence?
Authors: DASSEN WILLEM RM , DEN DULK KAREL , WELLENS HEIN JJ
Published: July 2006

For over twenty years computer programs have been written for applications in cardiology. Approximately one decode ago the first Expert Systems using knowledge on cardiology were built. The use of Expert System shells enabled a breakthrough. Many systems were developed, each covering a small part of cardiology. In the pacing environment Expert Systems can be used to select the optimal pacemaker therapy or to analyze complex pacemaker electrocardiograms. With the help of these artificial intelligence techniques pacemakers can be designed, that behave in an intelligent way. Finally this knowledge representation enables the reproducible simulation of the heart‐pacemaker interaction.
Pacemaker‐Mediated Tachycardia from a Single Chamber Temperature Sensitive Pacemaker
Authors: VOLOSIN KENT J. , O'CONNOR WILLIAM H. , FABISZEWSKI ROSEMARY , WAXMAN HARVEY L.
Published: July 2006

VOLOSIN, KJ. et al.: Pacemaker‐Mediated Tachycardia from a Single Chamber Temperature Sensitive Pacemaker This report describes a case of pacemaker‐mediated tachycardia from a single chamber temperature sensitive rate modulated pacemaker. The patient experienced diaphragmatic pacing that produced an increase in right ventricular blood temperature. This temperature increase was sensed by the pacemaker and led lo sustained upper rate limit pacing. Decreasing the ventricular output to prevent diaphragmatic capture eliminated further episodes of pacemaker‐mediated tachycardia.
Behavior of a Respiratory Driven Pacemaker and Direct Respiratory Measurements
Authors: JORDAENS LUC , BERGHMANS LUC , VAN WASSENHOVE ETIENNE , CLEMENT DENIS L.
Published: July 2006

JORDAENS. L., et al.: Behavior of a Respiratory Driven Pacemaker and Direct Respiratory Measurements In 10 patients with a mean age of 76 ± 8 years, a rate responsive pacemaker (Meta‐MV, Telectronics) was implanted in the left pectoral site. An exercise test was performed in SSI (“adaptive”) mode, allowing the device to measure the changes in thoracic impedance. The “slope number” at maximal exercise was chosen to program the pacemaker for a second exercise test in rate responsive mode. Direct measurements of respiratory rate and minute volume were correlated with the pacing rate. After 1 minute of exercise, pacing rate increased by 6% and it decreased smoothly after maximal exercise. The programmed maximal rate was reached at the maximum exercise level in six patients. During 24‐hour Holter recording, the mean maximal pacing rate was 103 ± 18 beats/min. For individual patients, a good correlation of pacing rate with respiratory rate (r = 0.757), oxygen consumption (r = 0.731), and minute volume (r = 0.800) was observed. The data from the entire group showed a highly significant correlation of changes in pacing rate and in respiratory parameters for different levels of exercise and recovery. In a subgroup of five patients, the slope numbers at maximal exercise were reproducible after 10 months. It was concluded that minute volume and its changes were recognized in a reliable way by the Meta‐MV pacemaker.
Sinus Node Dysfunction and Sudden Cardiac Death Following Treatment with Encainide
Authors: LEMERY ROBERT , TALAJIC MARIO , NATTEL STANLEY , THEROUX PIERRE , ROY DENIS
Published: July 2006

LEMERY, R. et al. Sinus Node Dysfunction and Sudden Cardiac Death Following Treatment with Encainide Encainide, a class Ic drug, is generally thought of as having little effect on sinus node function. In this article, we present the clinical course and electrophysiological findings of a patient who had cardiac arrest after 1 week of encainide therapy for ventricular extrasystoles. No ventricular tachyarrhythmias were induced during programmed ventricular stimulation (baseline study and while receiving encainide therapy). Prior to encainide therapy, sinus node function was normal, but clinical observations after admission for cardiac arrest and subsequent electrophysiological study revealed that encainide had caused striking impairments in sinus node function. During a 6‐month follow‐up without antiarrhythmic drug treatment, this patient has had an uneventful course. We concluded that encainide can cause severe and life‐threatening sinus node dysfunction.
Cross‐Talk in Bipolar Pacemakers
Authors: COMBS WILLIAM J. , REYNOLDS DWIGHT W. , SHARMA ARJUN D. , BENNETT TOM D.
Published: July 2006

COMBS, W.J., et al.: Cross‐Talk in Bipolar Pacemakers Investigation of dual chamber pacing and sensing interactions at high rates is becoming increasingly important with the advent of sensor driven dual chamber pacemakers. The present study was designed to investigate the pacemaker and lead interactions that will affect cross‐talk during high rate atrial and ventricular pacing. The study was divided into two phases, phase one investigated the mechanisms of cross‐talk using standard pacemaker circuitry and various electrode types in a canine model. In six dogs with complete heart block, dual chamber pacing was carried out with four lead types at increasing pacing rates, while output of the ventricular sense amplifier of a pacemaker breadboard was monitored. Ventricular sense amplifier output signals (n = 332) progressively increased from 31.5 ± 18.3 mV at 100 ppm to 102 ± 55 mV at 160 ppm. Smooth platinum‐iridium and platinized leads were statistically different at higher pacing rates (P < 0.05). This signal level is sufficient to lead to a ventricular sensing event, In a second phase of the study, the incidence of cross‐talk at high pacing rates was studied in patients with implantable dual chamber bipolar pacemakers. In 166 clinical trials on 106 patients with the same pacemaker, there was evidence of cross‐talk in 1/59 cases at 110 ppm and 3/47 at 130 ppm, but none at higher rates. We conclude that in both the acute canine experiments and chronic human studies the mechanisms of cross‐talk in this bipolar pacing system may be related to the method of amplifier blanking and residual polarization voltage on the lead, rather than cross‐talk caused by coupling of atrial pacing energy into the ventricular sense amplifier. Human data is too limited to independently support this hypothesis. However, the low incidence of cross‐talk in human studies indicates that cross‐talk in bipolar DDD pacemakers may be less likely than in unipolar DDD pacemakers.
Transvenous Ablation with High Frequency Energy for Atrioventricular Junctional (AV Nodal) Reentrant Tachycardia
Authors: SANJUAN R. , MORELL S. , CIVERA R. GARCIA , MUÑOZ J. , SANCHIS J. , CHORRO J. , LLAVADOR J. , LOPEZ‐MERINO V.
Published: July 2006

SANJUAN, R., et al.: Transvenous ablation with high frequency energy for atrioventricular junctional (AV nodal) reentrant tachycardia We performed transcatheter AV junction ablation with high frequency energy in four patients with AV nodal reentrant tachycardia where extensive trials of several antiarrhythmic drugs failed to prevent further recurrences of tachycardia. Initially high frequency catheter ablation induced complete AV block in all patients. A recuperation of AV l:1 conduction followed some time later, persisting in follow‐up. No complications have been encountered in either the acute phase or the follow‐up (from 6 to 8 months; mean ± SD: 8.7 ± 2.5 months). The electrophysiological study was carried out 6 weeks following ablation, and all patients showed AV 1:1 conduction. No dual nodal pathway was encountered and no tachycardia could be triggered. With refinement of the method, the potential application of high frequency energy to interrupt intranodal or perinodal connections responsible for reentrant supraventricular tachycardia or to retard AV nodal conduction appears promising.
Entrainment of Ventricular Tachycardia by Sinus Rhythm
Authors: KREMERS MARK S. , LEVINE BENJAMIN , SPIELBERGER RICARDO , PASSOS‐COELHO JOSE
Published: July 2006

KREMERS, M.S., et al. Entrainment of Ventricular Tachycardia by Sinus Rhythm Entrainment of ventricular tachycardia (VT) may be manifest as fixed and progressive QRS fusion with ventricular and, rarely, atrial pacing. Only a single example of spontaneous VT entrainment by another rhythm, rapid atrioventricular nodal tachycardia, has been reported. This article describes an example of fixed and progressive QRS fusion between conducted sinus rhythm and VT consistent with entrainment. In contrast to entrainment with pacing, entrainment of VT by sinus rhythm occurred with drug‐mediated arrhythmia slowing and demonstrated progressive QRS fusion at a constant cycle length. However, it did not demonstrate unfused but entrained QRS complexes. The resulting short PR interval and wide QRS mimicked a preexcited rhythm.
Ablation of a Left‐Sided Free‐Wall Accessory Pathway by Percutaneous Catheter Application of Radiofrequency Current in a Patient with the Wolff‐Parkinson‐White Syndrome
Authors: KUCK KARL‐HEINZ , KUNZE KLAUS‐PETER , SCHLÜTER MICHAEL , GEICER MANFRED , JACKMAN WARREN M.
Published: July 2006

KUCK, K‐H., et al.: Ablation of a Left‐Sided Free‐Wall Accessory Pathway by Percutaneous Catheter Application of Radiofrequency Current in a Patient with the Wolff‐Parkinson‐White Syndrome A case is presented of a 20‐year‐old woman with a history of three episodes of syncope within the last 4 years, which was caused by a rapid ventricular response to atrial fibrillation via a left‐sided posterior accessory pathway. A variety of antiarrhythmic agents had failed to control the arrhythmia. Using a novel dual catheter approach, with one catheter in the coronary sinus and an adjacent catheter in the left ventricle close to the mitral annulus, accessory pathway conduction was successfully interrupted by two radiofrequency current applications between the tip electrodes of the two catheters. During follow‐up, 12‐lead electrocardiogroms have been normal and the patient has been asymptomatic.
Signal‐Averaged Electrocardiography of the Terminal QRS in Healthy Young Adults
Authors: DANFORD DAVID A. , STELLING JONATHAN A. , KUGLER JOHN D. , CHEATHAM JOHN P. , LATSON LARRY A. , GUMBINER CARL H. , HOFSGHIRE PHILIP J.
Published: July 2006

DANFORD, D.A., et al.: Signal‐Averaged Electrocardiography of the Terminal QRS in Healthy Young Adults Interpretation of signal‐averaged electrocardiograms (SAECG) in the young could he of value in detecting those at risk for episodic ventricular tachycardia, but suffers from a lack of data in normal young people. The purpose of this study is to determine normal values for QRS duration and the duration and amplitude of terminal potentials on the SAECG in young adults. Thirty‐two normal medical students were examined. With high pass fütering at 25 Hz, normal total QRS duration (QRS) varied as a function of sex and hody size whereas low amplitude signal duration (LAS) did not. Ninety‐five percent confidence limits are: QRS (male) 85–117 msec. QRS (female) 76–102 msec, and LAS 6–35 msec. Root mean square voltage of the terminal QRS showed a broad scatter, however none was < 20 microvolts. High pass filtering at 40 Hz did not change the QRS duration, but resulted in significantly longer LAS duration and diminished RMS voltage. Because of the longer QRS and shorter LAS previously reported in the presence of right bundle branch hlock, the normal values reported here should not be applied in the presence of intraventricular conduction delay following surgical repair of congenital heart disease. They will, however, provide a basis for interpretation of SAECG in young adults with normal QRS duration.
Left Ventricular Pressure Measurement During Noninvasive Transcutaneous Cardiac Pacing
Authors: TRIGANO JACQUES ALEXANDRE , REMOND JEAN MARC , MOUROT FRANCK , BIRKUI PIERRE , LEVY SAMUEL
Published: July 2006

TRIGANO, J. A., et al.: Left Venlricular Pressure Measurement During Noninvasive Transcutanenous Cardiac Pacing In a pacemaker‐dependant patient, the hemodynamic response during external transcutaneous and endocardial sequential pacing was evaluated by left ventricular pressure monitoring. A single ventricular pacing mode with hemodynamic effect of atrioventricular asynchrony was shown during external pacing.
Permanent Transvenous Pacing After a Mustard Procedure
Authors: HANDLER CLIVE E. , GREAVES MELANIE , WALKER J. MALCOLM
Published: July 2006

HANDLER, C.E., et al.: Permanent Transvenous Pacing After a Mustard Procedure We report the case of a 20‐year‐old man born with transposition of the great vessels who underwent emergency balloon septostomy and subsequently a Mustard procedure. When aged 20 years, he had several syncopal attacks due to sinoatrial disease for which he was simply and successfully paced transvenously in VVI mode.