bluuebunny/crossref_metadata_2025 huggingface dataset:
Automatic Implantable Defibrillator Discharge Resulting From Routine Pacemaker Programming
Authors: GOTTLIEB CHARLES , MILLER JOHN M. , ROSENTHAL MARK E. , MARCHLINSKI FRANCIS E.
Published: July 2006

A middle‐aged gentleman with an idiopathic dilated cardiomyopathy, drug‐refractory sustained ventricular arrhythmia, and high‐degree AV block was managed with an automatic implantable cardioverter‐defibrillator (AICD) and a Cordis Multicor II VVI pacemaker. During a routine follow‐up visit, the pacemaker threshold was determined. Seven seconds after reprogramming the Cordis pacemaker to the “stat” WI mode, the AICD discharged. The time to discharge after reprogramming (he pacemaker equalled (he previously determined AICD charge time. No other rhythm disturbance was documented and the rate with double counting of pacemaker stimulus and QRS complex was less than the triggering rate/or the AICD. In conclusion, the AICD can be triggered by pacemaker programming signals unrelated to subsequent peacemaker function.
QT‐Related Rate‐Responsive Pacing During Acute Myocardial Infarction
Authors: ROBBENS ERWIN J. , CLEMENT DENIS L. , JORDAENS LUC J.
Published: July 2006

We studied the findings in a patient who had a TX 915 pacemaker and who was suffering from an acute inferior myocardial infarction. On admission, we observed pacing at the upper rate limit due to excessive adrenergic tone. Shortly thereafter a strong vagal reaction occurred, and the pacing rate fell back to the lower rate limit. This condition was improved with atropine. Conclusions: (1) In the described condition the TX pacemaker behaved in a very “physiological” fashion; (2) Sudden strong cholinergic activity lengthened the QT interval; (3) Programming of a steep slope must be avoided in coronary artery disease; (4) Stimulus‐ T‐wave intervals at maximal adrenergic and cholinergic stimulation should be taken into account when programming the slope and the T‐wave sensing window.
Implantation of a Dual Chamber Pacemaker in a Patient with Persistent Left Superior Vena Cava
Authors: DIRIX LUC Y. , KERSSCHOT IVO E. , EIERENS HERBERT , GOETHALS MARC A. , VAN DAELE GUY , CLAESSEN GUIDO
Published: July 2006

A patient underwent dual chamber pacemaker implantation by puncture of the left subclavian vein. During the procedure we observed persistence of the left superior vena cava. A “J‐shaped” atrial lead was used for ventricular pacing with excellent long‐term results. This technique can be a valuable alternative when confronted with the problem of persistent left superior vena cava during pacemaker implantation.
Vasovagal Syncope During Rectosigmoidoscopy: Report of a Case
Authors: SELLEGER C. , ADAMEC R. , MORABIA A. , ZIMMERMANN M.
Published: July 2006

Cardioinhibitory vasovagal syncope with sinus arrest and asystole of 28 seconds' duration occurred during rectosigmoidoscopy in a patient with frequent previous symptoms and a syncopal episode. A ventricular inhibited pacemaker was implanted and the patient has remained asymptomatic for 18 months.
Intermittent Preexcitation: Marked Enhancement of Anterograde Conduction in the Atrioventricular Accessory Pathway with Isoproterenol
Authors: EASLEY ARTHUR R. , SENSECQUA JAMES E. , MANN DAVID E. , REITER MICHAEL J.
Published: July 2006

A 29‐year‐old man presented with intermittent preexcitation and exertional syncope. Electrophysiological evaluation in (he control state demonstrated a single, left posterior free‐wall atrioventricular accessory pathway. The anterograde and retrograde effective refractory periods and block cycle lengths were long in the control state. No tachycardias were induced during programmed electrical stimulation. After intravenous administration of isoproterenol, anterograde conduction of the accessory pathway was markedly enhanced (block cycle length shortened 45% to <240 ms) and rapid antidromic reciprocating tachycardia (CL = 250 ms) associated with syncope was observed. Following successful surgical dissection of the accessory pathway the patient has been without tachycardia or exertional symptoms. We conclude that, under the influence of exercise or emotion, patients with intermittent preexcitation may be at risk for serious arrhythmias.
Transcutaneous Pacing for Cardiac Emergencies
Authors: ROSENTHAL ERIC , THOMAS NIGEL , QUINN ELIZABETH , GHAMBERLAIN DOUGLAS , VINGENT RIGHARD
Published: July 2006

Transcutaneous cardiac pacing using the Pace‐Aid (CaTcliac Resuscitator Corporation) was assessed in 32 emergency patients presenting with profound bradycardia or asystole who had failed to recover with advanced life support including the use ofepinephrine. Pacing stimuli, pulse width 20 ms at 50, 100, or 200 mA, were delivered through two 8 cm gel‐pad electrodes placed antero‐posteriorly on the chest. By ECG criteria, definite electrical capture was achieved in a total of five patients and possible capture in a further 16. Of the 21 patients presenting in asystole 11 showed possible electrical capture only. No evidence of capture was seen in one third of the patients studied. Use of the Pace‐Aid resulted in a paipable pulse in a total of seven patients. Four of the 11 patients with profound bradycardia survived to receive temporary transvenous pacing; two were eventually discharged. None in the asystolic group survived. Difficulties in using the Pace‐Aid resulted from electrical overload by the pacing impulse that obscured the evidence for electrical capture, and intense muscle contraction that hindered reliable palpation of the arterial pulse. Transcutaneous pacing can occasionally be of value even at a late stage in the emergency treatment of profound faradycardia but is unlikely to be worthwhile in complete asystole.
Catheter Recording of Left Atrial Activation from Left Pulmonary Artery in the Wolff‐Parkinson‐White Syndrome: Validation of the Technique with Intraoperative Mapping Results
Authors: LACOMBE PIERRK , SADR‐AMELI MOHAMMAD ALI , PAGÉ PIERRE , CARDINAL RENE , NADEAU REGINALD A. , SHENASA MOHAMMAD
Published: July 2006

Accurate localization of accessory pathways (AP) in the Wolf‐Parkinson‐White (WPW) syndrome requires detailed atrial mapping. Coronary sinus catheterization is so far the most accurate method of left atrial mapping, but it can be technically difficult in some patients. We evaluated the feasibility of left atrial mapping from the left pulmonary artery in 24 patients with WPW syndrome. AU patients except one underwent surgical cryoablation of their AP and the results of intraoperative mapping are available for comparison. Mapping in sinus rhythm showed recording of atrial activity in the distal left pulmonary artery occurred 56 ± 20 ms after activation of high right atrium and 24 ± 4 ms after activation in the His bundle area, but coincident with left atrial activation in the distal coronary sinus (56 ± 20 and 53 ± 13, respectively. Mapping during ventricular pacing or orthodromic tachycardia could differentiate patients as having a right sided, left sided or paraseptal first site of activation. Eleven patients had a left lateral AP, four had a left posterior AP, five had left posteroseptal AP and one had a left anterior AP. The remaining three patients had a right sided AP. Intraoperative results correlated with pre‐operative findings in 22 out of 23 (95%) patients who underwent surgical ablation of AP. Thus, recordings form the left pulmonary artery reflect left atrial activity and may be of aid in localizing an AP, especially when coronary sinus recordings cannot be obtained. This technique, however, should not replace the more accurate method of coronary sinus mapping.
An Advanced Data Base Pacemaker Follow‐up System That's Customizable
Authors: BATEY ROBERT L. , SWEESY MARK W , ELWOOD PATRICK S.
Published: July 2006

In an effort to deal with the volumes of information gathered from pacemaker follow‐up, the obvious need for a computerized data base was realized. In order to meet specific goals and needs, an advanced relational data base program has custom designed for pacemaker follow‐up. The program has the ability to store and report all follow‐up data throughout the life of each patient on a relatively few page report. The software also includes files for generator specifications, recalls and pulse generator and lead prices and warranties. The program is quite flexible and can be customized to particular follow‐up clinics.
Bradyarrhythmia Profile and Associated Diseases in 1,265 Patients With Cardiac Pacing
Authors: LEVANDER‐LINDGREN MAJ , LANTZ BO
Published: July 2006

Twelve hundred and sixty‐five patients with implanted cardiac pacemakers were reviewed for known associated conditions and for the resulting bradycardia patterns. The group bradyarrhythmia profile was AV block in 75%, sick sinus syndrome (SSS) in 21% and combined arrhythmias in 4%. Thyroid diseases and acquired valvular disease were frequently associated with AV block especially of the Wenckebach type. Sick sinus syndrome occurred significantly more frequently in women (28%) than in men (26%). Isolated bradyarrhythmias (i.e., with no associated disease) were 22% of the entire group with a 26% incidence of SSS and with a significant association with previous gastric resection, pernicious anemia, and malabsorption compared to the groups with other associated diseases. Degenerative cardiac lesions caused by malabsorption and undiagnosed hypothyroidism in elderly women may contribute to the group of apparently isolated bradyarrhythmias.
Comparison of Two Myoepicardial Pacemaker Leads: Follow‐up in 80 Children, Adolescents, and Young Adults
Authors: KUGLER JOHN , MONSOUR WILLIAM , BLODGETT CATHY , CHEATHAM JOHN , GUMBINER CARL , HOFSCHIRE PHILIP , LATSON LARRY , FLEMING WILLIAM
Published: July 2006

Although severai types of commercially available epicardial leads exist, few postimplantation data have been reported. To compare “screw‐in” (6917–35) leads with “stab‐on” leads (4951–35) from the same manufacturer, we reviewed the records of 80 young patients (age 8 days to 29 years) who underwent ventricular epicardial pacemaker implantation from 1973 to 1986. Follow‐up for the 57 patients with the 6917–35 model ranged from 3 months to 17 years (median 6.5 years) and for the 23 patients with the 4951–35 model 9 days to 4.25 years (median 2.0 years). Actuarial life table analysis revealed significantly (P < 0.001) fewer 4951–35 leads were functioning at each of 1–5 years after implant, compared to the 6917–35 leads. Analysis of available threshold pulse width data revealed no difference (P = 0.08) acutely (6 weeks after implant), but a significantly (P = 0.05) higher mean threshold for the 4951–35 leads was found chronically. No significant correlation was found for lead failure with age, underlying heart disease, lead site (i.e., left or right ventricle), or surgical approach. Using the sutureless, stab‐on technique, the 4951–35 lead is associated with higher thresholds and lower survival rate when compared to the 6917–35 lead.
A Canine Model of Torsades de Pointes
Authors: LEICHTER DONALD , DANILO PETER , BOYDEN PENELOPE , ROSEN TOVE S. , ROSEN MICHAEL R.
Published: July 2006

Although quinidine has been reported to induce QT interval prolongation and torsades de pointes clinically, the only experimental model currently available for quinidine‐induced torsades de pointes requires the concurrent use of ischemia, reperfusion and cardiac pacing of the isolated, perfused heart. Our purpose in this study was to determine the circumstances under which quinidine might elicit torsades de pointes consistently in the intact dog. We found that maintenance of therapeutic plasma quinidine concentrations, alone, did not induce the arrhythmia. Rather, arrhythmia induction required the additional application of aconitine, which induces early afterdepolarizations and triggered activity. When aconitine was applied to two epicardial sites in dogs having quinidine‐induced QT interval prolongation > 10%, torsades de pointes occurred in 80% of instances. When QT prolongation was < 10%, aconitine‐induced torsades de pointes was seen in only 21% of animals. Our results suggest that in a previously healthy heart quinidine‐induced QT prolongation is, itself, insufficient to induce torsades de pointes consistently, and two independent sites of ectopic activity are needed as well. The ectopic foci appear to modulate one another's impulse initiation or activation sequence, thereby giving rise to the classical “twisting of the points” associated with the arrhythmia.
Implanted Automatic Defibrillators: Effects of Drugs and Pacemakers
Authors: SINGER IGOR , GUARNIERI THOMAS , KUPERSMITH JOEL
Published: July 2006

The automatic implantable cardioverter defibrillator is an effective device for prevention of sudden ive device for prevention of sudden cardiac death. Patients who require the implantation of the device often require permanent pacing for symptomatic bradyarrhythmias and may require antiarrhythmic drug therapy. Antiarrhythmic drugs may after the defibrillation thresholds, arrhythmia cycle length and frequency, pacing thresholds and postshock excitability. Interactions between the defibrillator and the pacemaker may result in sensing problems, leading to multiple counting and inappropriate shocks, or ventricular fibrillation nondetection, sensing or capture failure post defibrillation and pacemaker reprogramming induced by defibrillator discharge. The potential for interactions will increase as the new generation of programmable defibrillators become clinically available, combining features of permanent pacemakers, antitachycardia pacemakers and defibrillators.
STIMAREC REPORT
Authors: GODIN J.F. , PETITOT J.C.
Published: July 2006

National delegates: Austria (A): K. Steinbach; Belgium (B): E. Installé; Finland (SF): K. Soininen; France (F); J. F. Godin; Germany F.R.(D): X…; Hungary (H): F. Renyi‐Vamos; Italy (I): G. Feruglio; The Netherlands (NL): L. M. Van Gelder Norway (N): H, Grendahl; Poland (PL); M. J. Stopczyk; Portugal (P); S. S. Amram; South Africa (SA); I. W. P. Obel; Spain (E): S. Botella Solana; Sweden (S); X…; Switzerland (CH); I. Babotai; United Kingdom (GB); A. Rickards; Yugoslavia (YU): M. Djordjevic.
Contribution of Atrioventricular Synchrony to Left Ventricular Systolic Function in a Closed‐Chest Canine Model of Complete Heart Block: Implications for Single‐Chamber Rate‐Variable Cardiac Pacing
Authors: O'CONNOR ALLEN MELODY J. , ARENTZEN CARL E. , ANDERSON ROBERT W. , VISNER MARC S. , FETTER JOSEPH , BENDITT DAVID G.
Published: July 2006

This study assessed the impact of atrioventricular (AV) synchrony on characteristics of left ventricular (LV) systolic function during ventricular pacing over a wide heart rate range in a conscious closed‐chest canine model of complete AV block. Ten healthy adult dogs underwent thoracotomy during which complete AV block was created by formaldehyde injection, and paired ultrasonic sonomicrometers were positioned on the LV anterior‐posterior minor axis. Following recovery from surgery, peak and end‐diastolic LV transmural pressure, maximum dP/dt, stroke work, end‐diastolic minor axis dimension, and maximum velocity of shortening, were quantitated at heart rates of 80, 100, 120, 140, and 160 beats per minute (bpm) during both ventricular pacing alone and AV sequential pacing with increasing AV intervals (0, 50, 100, 150, 200, 250, and 300 ms). Over the heart rate range tested, parameters of LV systolic function did not differ significantly during ventricular pacing with or without AV synchrony. For example, during ventricular pacing alone maximum LV dP/dt varied from 2110 ± 70 mmHg/s to 2463 ± 567 mmHg/s, a range essentially identical to that observed in the presence of AV synchrony. On the other hand, although the impact on LV performance of varying AV interval from 0 to 300 ms was small, differences tended to become more pronounced at higher pacing rates. At 80 bpm, neither stroke work nor maximum LV dP/dt were affected by change in AV interval, while at heart rates 120 bpm both stroke work and LV dP/dt tended to maximize at AV intervals of 50 and 100 ms and thereafter declined. Thus, findings in this study indicated that LV systolic function in the normal in situ heart is not adversely affected by absence of AV synchrony over a wide heart rate range.
Sudden Death Associated with Alcohol Consumption
Authors: PANOS RALPH J. , SUTTON FREDERICK J. , YOUNG‐HYMAN PAUL , PETERS ROBERT
Published: July 2006

Evaluation of a binge drinker who died suddenly after a weekend of heavy beer consumption, and had been resuscitated successfully, revealed no evidence of clinically detectable heart disease. Baseline electrophysiological testing was normal. Following intravenous ethanol infusion, paired ventricular extrastimuli from the right ventricle induced a rapid polymorphic ventricular tachycardia requiring cardioversion. Repeat electrophysiological testing 24 hours later without alcohol infusion was again normal. The patient was discharged on no medications and was instructed to refrain from drinking alcohol. Approximately 3 months later the patient died suddenly after heavy beer consumption. Alcohol should be considered in the evaluation of survivors of cardiac arrest and alcohol challenge may be useful in their evaluation.
Cumulative Effects of Amiodarone on Inducibility of Ventricular Tachycardia: Implications for Electrophysiological Testing
Authors: KRAFCHEK JACK , LIN HUANG‐TA , BECKMAN KAREN J. , NIELSEN ANTON P. , MAGRO SHARON A. , HARGIS JAYNE , WYNDHAM CHRISTOPHER R. C.
Published: July 2006

To determine whether the slow onset of action of amiodarone might result in a delayed effect on the inducibility of sustained ventricular arrhythmias. 45 patients with ischemic heart disease and inducible sustained monomorphic ventricular tachycardia were prospectively studied. Each patient had at least one initial repeat study on amiodarone and those with persistently inducible arrhythmias were rescheduled for further studies over the following 24 weeks. After 2–3 weeks of amiodarone therapy, nine patients no longer had inducible tachycardias, and tachycardia in another eight patients (18%) later became noninducible. Using life‐table methods, analysis based on the results of the first re‐study showed 18‐month recurrence rates of 43% in the inducible vs 17% in the noninducible groups (p = 0.056). When the results of additional testing were then used to reclassify patients, the recurrence rates for these two groups were 50% and 17%, respectively (p = 0.004). Observation of blood pressure and level of consciousness during induced arrhythmias was also predictive of clinical tolerance in patients having recurrences; 16 of 19 patients experienced symptoms of similar severity to those produced during testing. We conclude; (1) early testing of amiodarone may result in misclassification of some patients as remaining inducible; (2) re‐testing at a later time more accurately predicts tachycardia recurrence; (3) observation of hemodynamic response also provides important prognostic information.
Radiofrequency Catheter Ablation of the Left and Right Ventricles: Anatomic and Electrophysiologic Observations
Authors: HUANG SHOEI K. STEPHEN , GRAHAM ANNA R. , WHARTON KEITH
Published: July 2006

Certain untoward effects associated with the use of direct‐current electrical catheter ablation of the ventricular endomyocardium have been noted. We assessed the efficacy and safety of closed‐chest catheter ablation of the left and right ventricles using radio frequency (RF) energy (750 kHz) in six dogs. Mean HF energies between 93 and 123 joules (J) were randomly delivered to three left ventricular (LV) sites via two distal adjacent electrodes (bipolar configuration) using 6–7F USCI tripolar or quadripolar catheters with an interelectrode distance of 5–10 mm. Another 90–143 J were given to two right ventricular (RV) sites in single or multiple divided applications between a distal electrode and an external patch electrode (unipolar configuration). Ventricular arrhythmias were not observed during application of RF energy. Programmed ventricular stimulation before and after the procedure did not induce ventricular tachycardia (VT) or fibrillation except in one dog who had inducible VT prior to ablation. There were no significant changes in LV and RV elective refractory periods after the procedures. Occasional premature ventricular beats and rare episodes of non‐sustained VT (3–12 beats) were observed in ambulatory electrocardiographic recordings (13–24 hrs) done immediately after ablation. Dogs were sacrificed after 4–5 days. Pathology showed well‐demarcated round or ovoid lesions of varying sizes, Murai thrombus was found in one dog. Microscopic findings consisted of circumscribed areas of coagulation necrosis with a peripheral zone of cellular infiltration. Transmural necrosis without perforation was occasionally seen in the thin RV wall when higher energies were delivered. In conclusion, discrete areas of desiccation injury in the ventricles can be achieved by transcatheter bipolar or unipolar ablation using RF energy. The complications associated with this method appear to be minimal. Further experiments are needed to evaluate its potential for catheter ablation of ventricular tachycardia.
Decrease in Canine Endocardial and Epicardial Electrogram Voltages with Exercise: Implications for Pacemaker Sensing
Authors: BRICKER J. TIMOTHY , WARD KENT A. , ZINNER ALEX , GILLETTE PAUL C.
Published: July 2006

Individuals with permanently implanted pacemakers who have normal sensing and pacing at rest may demonstrate abnormalities, particularly of atrial sensing, with exercise. Exercise is known to cause changes in the surface electrocardiographic voltages. The purpose of this study was to evaluate changes in endocardial and epicardial voltages during exercise in canines with permanently implanted pacing leads similar to those permanently implanted in humans with pacemakers. Six adult mongrel dogs were equipped with transvenous atrial and ventricular endocardial bipolar screw‐in leads from a jugular venosection, and with atrial and ventricular bipolar stab‐on leads from a left thoracotomy. Exercise was performed at one week following implantation and at weekly intervals for a total of 4 weeks. The animals were studied at rest and at a single workload of 3 miles per hour at a 30% elevation. Unfiltered electrograms were recorded with a VR‐12 Electronics‐for‐Medicine photographic recorder. The mean decreases of electrograms with exercise from resting voltage were: 15% for atrial endocardial unipolar leads: 11% for atrial endocardial bipolar leads; 4% for atrial epicardial unipolar leads; 15% for atrial epicardial bipolar leads; 8% for ventricular endocardial unipolar leads; 18% for ventricular endocardial bipolar leads; 0.1% for ventricular epicardial unipolar leads and 5% for ventricular epicardial bipolar leads.
Torsade de Pointes and Other Pause‐Induced Ventricular Tachycardias: The Short‐Long‐Short Sequence and Early Afterdepolarizations
Authors: CRANEFIELD PAUL F. , ARONSON RONALD S.
Published: July 2006

The early after depolarization, which is an interruption of repolarization, can evoke a second upstroke or a salvo of action potentials. It is suggested that the electrophysiological characteristics of the early after depolarization can produce a lengthening of the QT interval and that the second upstroke and salvo of activity that may follow, it can explain many features of torsade de pointes and of certain other ventricular tachycardias. The early after depolarization, torsade de pointes, and repetitive monomorphic idiopathic ventricular tachycardia are all induced hy bradycardia or by a preceding long RH interal. The R‐on‐T phenomenon is also discussed.
Mathematical Descriptions of AV Nodal Function Curves in Dogs
Authors: CHORRO FRANCISCO J. , RUIZ‐CRANELL RICARDO , CASADAN ERNESTO , CARCIA‐CIVERA ROBERTO , SUCH LUIS , LOPEZ‐MERINO VICENTE
Published: July 2006

Thirty‐four anaestheized mongrel dogs subjected to thoracotomy were used to study AV node conduction during atrial pacing at increasing rates. Eplcardial atrial electrodes were used, together with endocavitary recordings of His bundle electrogram. An analysis was made of the repercussions involved in using four different mathematical functions describing nodal conduction; three were nonlinear (exponential and hyperbolic A and B) and one linear. In the case of the first three, the consequences of using a direct nonlinear data‐fitting procedure or an indirect procedure by linear transformations of the functions were studied. The exponential and hyperbolic B functions provided the least mean squared residual in quantifying nodal conduction (8.6 ± 10.8 ms2 and 10.8 ± 13.9 ms2, respectively). The use of nonlinear function transformation into a linear representation caused Joss of precision in the fit to the data in the case of the exponential function (18.3 ± 22.2 ms2 versus 8.Q ± 10.8 ms2, p < 0.01] and, to a lesser extent, in the case of the hyperbolic B function [12.5 ± 16.4 ms2 versus 10.8 ± 13.9 ms2, P < 0.05).
Shift of Atrial Reentrant Tachycardia with Transient Entrainment to an Uncommon and a Common Type of Atrial Flutter
Authors: KOMATSU CHIKAYOSHI , ISHINAGA TAKANARI , TATEISHI OSAMU , TOKUHISA YASUTAKA , TANOIRI TAKASHI , YOSHIMURA SHOZO , SUZUKI SHIGERU , ARAI TATSUTA
Published: July 2006

Atrial reentrant tachycardia (ART) which demonstrated transient entrainment shifted to an uncommon type of atrial flutter (AF) with premature atrial stimulation, and then returned to ART spontaneously, Subsequently, this ART shifted to a common type of AF by rapid atrial pacing, which was further transformed into an uncommon type of AF and finally terminated by rapid atrial pacing. The mechanism of AF in clinical cases is still controversial, but in this case, AF, both uncommon and common types, is considered due to macro‐reentry within the atria. To explain (he shift of ART to AF and mutual transformation between common and uncommon type of AF, we made a schematic figure of reentry loop within (he atria of ART and AF.
A New Multisensor Pacing System Using Stroke Volume, Respiratory Rate, Mixed Venous Oxygen Saturation, And Temperature, Right Atrial Pressure, Right Ventricular Pressure, And dP/dt
Authors: STANGL KARL , WIRTZFELD ALEXANDER , HEINZE ROLAND , LAULE MICHAEL , SEITZ KLAUS , GÖBL GERHARD
Published: July 2006

A new multisensor pacing device using respiratory rate (RR), stroke volume fSV), oxygen saturation (SO2), temperature (T), right atrial pressure (RAPJ, right ventricular pressure (RVPJ and right ventricular dP/dt, has been developed. It consists of a 7F multisensor catheter and an external pacing unit. It allows simultaneous recording of the input signals and the corresponding data can be compared among the different parameters under identical conditions. Furthermore, several parameters can be combined in such a way as to form a new combination better suitable for rate responsive pacing. The response of each parameter to exercise was studied in 12 healthy volunteers (mean age:28 years). Exercise testing was carried out using a bicycle ergometer, with workloads up to 200 W. The dynamic characteristics, response and sensitivity to changes of workloads of each parameter were analyzed and compared to one another. SO2 proved to be a quick responding parameter (<10 sec) with higher sensitivity in the low exercise range (<75 WJ, T, on the other hand, responded slowly (>30 sec) to exercise changes and had the highest sensitivity in the exercise range beyond 75 W. RR displayed a slow response (>30 sec) and an adequate sensitivity was only found in the upper exercise range (>100 W). SV reacted rapidly to workload changes (<10 sec) but showed poor sensitivity at all exercise levels. RAP, RVP and dP/dt displayed quick responses and constantly good sensitivity throughout the workload range. Furthermore, respiratory rate was easily‐derived from the RAP curve. Special algorithms were developed for each parameter so that pacing rate would reproduce sinus rate behavior. We found that SO2 and all pressure parameter imitated sinus rate response quite well. When using parameter combinations, SO2 and T proved to be superior. Five patients (mean age 68 years) with third degree AV‐block were stimulated temporarily using this system. Compared to fixed rate stimulation [VVI 70], exercise performance improved, using SO2 as the input parameter for rate response, by 25% to 50%.
Respiratory‐Dependent Pacing: A Dual Response From A Single Sensor
Authors: WEBB STUART C. , LEWIS LEE M. , MORRIS‐THURGOOD JAYNE A. , PALMER RICHARD G. , SANDERSON JOHN E.
Published: July 2006

Five patients with respiratory dependent rate responsive pacemakers (Biorate HDP3, Biotec) were studied using ambulatory telemetry to evaluate the sensitivity of this pacing system to nonrespiratory signals. In each case the pacemaker was implanted in the left infraclavicular position with an impedance sensing electrode inserted into the subcutaneous tissues of the anterior chest wall. The pacing rate was 73 ± 2 beats per minute at rest and rose by 42 ± 5 beats per minute when the patients were walking with both arms swinging (mean ± SEMJ. Three of the five patients had sensing electrodes that extended across the midline. In this subgoup, pacing rate rose by 26 ±4 beats per minute when walking with arms held immobile and by 36 ± 2 beats per minute during sustained voluntary hyperventilation. These same activities did not elicit any appreciable changes in pacing rate in the remaining two patients whose sensing electrodes were confined to the left hemithorax. Recordings taken from all jive patients while they were standing upright and regularly swinging one upper limb showed an increase in pacing rate of 15 + 6 beats per minute with movement of the right arm and 46 + 8 with movement of the left. These observations establish that the Biorate RDP3 pacemaker is capable of responding both to changes in respiratory rate and to movement of the upper limbs. The sensitivity to limb movement is greatest when the chest wall impedance sensor does not extend across the midline and is most evident when the arm ipsilateral to the pacemaker is swung. This anomalous response may have a profound effect on pacing rate during certain forms of exercise and must be taken into account when programming the pacemaker to meet the heart rate requirements of individual patients.
Resetting of DDD Pulse Generators due to Cold Exposure
Authors: BAROLD S. SERGE , FALKOFF MICHAEL D. , ONG LING S. , HEINLE ROBERT A. , WILLIS JAMES E.
Published: July 2006

We encountered resetting of three DDD pulse generators to the VVI mode, one at the time of implantation and two others just before implantation, and we believe this resulted from cold exposure during shipment. Consequently we analyzed the effect of cold exposure on five lithium‐powered DDD pulse generators from different manufacturers. Cold exposure caused resetting of three of the five DDD pulse generators to the VVI mode. Only one of the reset pulse generators responded to application of the magnet by conversion to the asynchronous (VOOJ mode, while the other two remained in the VVI mode. All DDD pulse generators should be routinely interrogated before implantation. If found to be reset, the likelihood of cold exposure is very high and the pulse generator can generally be reprogrammed to the DDD mode. The absence of a magnet response in reset DDD pulse generators appropriately inhibited and functioning in the VVI mode should not be interpreted as component failure when no output is observed.
Rate Modulation by Arm Movements of the Respiratory Dependent Rate Responsive Pacemaker
Authors: LAU CHU‐PAK , RITCHE DON , BUTROUS GHAZWAN S. , WARD DAVID E. , CAMM A. JOHN
Published: July 2006

The rate response to arm movements of the respiratory dependent rate responsive pacemaker (RDP3, Biotec) was assessed in four patients implanted with this pacemaker. The pacemaker was implanted in the left prepectoral region and the auxiliary impedance measuring electrode positioned subcutaneously over the right second intercostal space with its tip lateral to the mid‐clavicular line. The lower rate of the pacemaker was programmed to 75 bpm. While holding the breath, swinging arm movements (30 times) resulted in rate acceleration. The peak rate was faster when the arm on the side of the auxiliary electrode was swung (mean ± SEM, 117 ±8 compared to 130 ± 5 bpm, P < 0.5). The mean rate response of the subjects to brie/ treadmill exercise (Bruce stage 1) performed with both hands holding the support rails, swinging the right arm only, swinging left arm only and swinging both arms were 108, 140, 135 and 128 bpm respectively. Impedance measurement confirmed the significant influence of arm movements on thoracic “impedance” changes, which was mainly caused by electrode motion artifacts affecting the two electrode measuring system. This effect was dependent on the relative positions of the impedance measuring electrodes (i.e., between the pacemaker casing the auxiliary lead). Subsequently the auxiliary lead of the respiratory pacemaker (MB‐1, and Biorate) was implanted in the lower part of the chest on the right sternal edge in another patient. Rate acceleration was only observed when the arm on the side of the pacemaker was swung. As arm movements often accompany physical activities, pacing rate can be affected and should be considered when programming this pacemaker.
Percutaneous Catheter Ablation at the Mitral Annulus in Canines Using a Bipolar Epicardial‐Endocardial Electrode Configuration
Authors: KUCK KARL‐HEINZ , JACKMAN WARREN M. , PITHA JAN , KUNZK KLAUS‐PETER , CARMEN LEE , SCHRÖDER SÖREN , NIENABER CHRISTOPH A.
Published: July 2006

For potential application in ablating left free‐wall accessory AV pathways with direct current shocks, a new epicardial‐endocardial electrode configuration, designed to focus the current field across the mitral annulus, was tested in dogs. A catheter electrode in (he coronary sinus (epicardial electrode) was used as the cathode, and a catheter electrode in the left ventricle (endocardial electrode) placed beneath the mitral valve, high against the mitral annulus and directly across from the epicardial electrode formed the anode. Two shocks, each of 30, 40, or 50 joules (J) were delivered in nine, three, and four dogs, respectively. The first shock was applied to the anterior or lateral wail and the second shock to the posterior wall, except in one dog which received one anterior and one lateral shock. Two dogs receiving 50] shocks died acutely, one due to rupture of the coronary sinus and cardiac tamponade and the other had unexplained electromechanical dissociation. The remaining 14 dogs tolerated the two shocks well and were sacrificed 3–5 days later for pathological examination of the heart. Shocks in the anterior and lateral regions produced atrial necrosis (height 1.5–11 mm, width 1.5–12 mm and depth 1–3 mm) in 10 of 14 dogs and ventricular necrosis (height 4–27 mm, width 4–33 mm, and depth 5–14 mm) in all 14 dogs. Ideal lesions with atrial necrosis extending down to the annulus and ventricular necrosis extending to the epicardial aspect of the ventricular crest occurred in five dogs in which the endocardial electrode was positioned high against the annulus. In the other nine dogs, the endocardial electrode was located 6–18 mm below the annulus, as estimated by the center of ventricular necrosis. In these dogs, the ventricular lesions did not extend to the epicardial aspect of the crest and, in four dogs, no atrial necrosis was found. Shocks delivered to the posterior wall produced no atrial or ventricular necrosis except in one dog receiving a 50 J shock. It is concluded that, using the epicardial‐endocardial electrode configuration with the LV catheter positioned high against the annulus, shocks of less than 50 J in dogs safely produce atrial and ventricular necrosis adjacent to the mitral annulus in the anterior and lateral regions but not in the posterior regions. Similar lesions in man may be capable of interrupting left anterior and lateral accessory AV pathways.
Undersensing in VVI‐Pacemakers Detected by Holter Monitoring
Authors: VAN GELDER L.M. , EL GAMAL M.I.H.
Published: July 2006

Episodic failure to sense cardiac activity, with emission of pacemaker stimuli, was unexpectedly found on Holter monitoring of two asymptomatic patients who had had normal function of a WI pacemaker on direct ECG recording. Pectoral muscle movement was then demonstrated to cause pacemaker noise reversion. After decrease of input sensitivity the phenomenon stopped.
Crosstalk During Bipolar Pacing
Authors: SWEESY MARK W. , BATEY ROBERT L. , FORNEY RICHARD C.
Published: July 2006

Bipolar sensing pulse generators were thought to have eliminated crosstalk problems evident in unipolar systems. Crosstalk has been observed in the Model 284–02* bipolar sensing pacemakers. These intermittent problems were resolved by decreasing atrial output, decreasing ventricular sensitivity or increasing the ventricular blanking period. Three patients had pacemaker crosstalk, two experienced symptoms analogous to pacemaker syndrome.
Study of the Evolution of Masked Bifascicular Block
Authors: BAYÉS DE LUNA ANTONIO , TORNER PELAYO , OTER RAMÓN , OCA FERNANDO , GUINDO JOSEP , RIVERA ISABEL , FORT DE RIBOT RAMÓN
Published: July 2006

Masked bifascicular block (MBB) (absent or minimal S in I and VL. high R in V; and ÂQRS approximately ‐60°) is a rare condition. We have found 16 such cases in the last 12 years, thirteen male and three female, mean age 70 ± 9 years. The conventional electrocardiogram was tabulated and the clinical features and evolution of the patients were followed over 39.1 ± 32 months. Ten patients required pacemakers, nine because of complete atrioventricular (AV) block or increase in the previous AV block. Seven patients died (follow‐up 27.3 ± 32 months), five from heart failure. This study shows: (1) MBB is a subgroup of patients with a high risk of advanced atrioventricular block; (2) a pacemaker implant does not significantly reduce the high mortality in this group because of the severity of the underlying disease; (3) these results should be evaluated in a larger series of patients in order to confirm our provisional results.
Hemodynamic Responses to Rapid Pacing: A Model for Tachycardia Differentiation
Authors: COHEN TODD J. , VELTRI ENRICO P. , LATTUCA J. JOHN , MOWER MORTON M.
Published: July 2006

The hemodynamic responses to rapid atrial and ventricular pacing were examined in 10 closed‐chest anesthetized dogs in an attempt to distinguish hemodynamically stable from unstable tachycardias. Pressure monitoring catheters were placed in the femoral artery, right atrium, and right ventricle to measure mean arterial pressure, mean right atrial pressure, and mean right ventricular pressure at baseline heart rate and after rapid high right atrial and right ventricular apex pacing. Pressures recorded during rapid pacing (average of the pressures at 30 and 60 seconds of pacing) at pacing rates of 180, 250, and 280/minute were compared to those recorded initially at baseline heart rates. Rapid right ventricular apex pacing resulted in significant increases in mean right atrial pressure (from 6 ± 1 mmHg (mean ± standard error) to 12 ± 1 mmHg, a 100% increase, P < 0.001) and mean right ventricular pressure (from 11 ±1 mmHg to 16 ± 1 mmHg, a 45% increase, p < 0.02) with marked hemodynamic compromise (mean arterial pressure decreased from 85 ± 6 mmHg to 50 ± 6 mmHg, a 41% decrease, P < 0.01). These parameters remained stable (no statistically significant difference from baseline) during high right atrial pacing. In half of the dogs high right atrial pacing at rates 250 resulted in atrioventricular Wenckebach. Thus, it is concluded that mean right atrial pressure and mean right ventricular pressure may be useful in distinguishing hemodynamically significant tachycardias, and in the future design of antitachycardia devices.
Selective Hypervagotonia Isolated to the Atrioventricular Node
Authors: RUBIN DAVID A. , NIEMINSKI KAREN E. , WOOLF PAUL , HERMAN MICHAEL V.
Published: July 2006

Thirteen patients with recurrent unexplained syncope or presyncope underwent electrophysiological evaluation. A prolonged effective refractory period and functional refractory period of the atrioventricular node as well as slow paced rate to atrioventricular block were the only abnormalities found. Ventricular tachycardia could not be induced. All electrophysiological abnormalities reverted to normal following atropine administration. These patients have selective hypervagotonia isolated to the atrioventricular node. Three of thirteen patients required permanent pacing, and one required propantheline to control recurrent symptoms. Selective hypervagotonia may be a distinct clinical entity that can cause symptoms and require therapy.
Direct Endocardial Recording and Catheter Ablation of an Accessory Pathway in a Patient with Incessant Supraventricular Tachycardia
Authors: WEBB JOHN G. , DOWNAR EUGENE , HARRIS LOUISE , ROSSALL RICHARD E.
Published: July 2006

A patient presented with incessant supraventricular tachycardia due to a concealed accessory pathway. The His bundle electrocardiogram showed a large discrete accessory pathway potential following ventricular activation and resulting in retrograde atrial activation. Percutaneous catheter ablation in the region of the accessory pathway potential left nodal conduction intact but prevented retrograde activation of the atria. Symptomatic tachycardia has not recurred. Direct endocardial recording of accessory pathway potentials is rare hut may offer the opportunity for catheter ablation.
Far‐Field QRS Complex Sensing Via the Atrial Pacemaker Lead. II. Prevalence, Clinical Significance and Possibility of Intraoperative Prediction in DDD Pacing.
Authors: BRANDT JOHAN , FÅHRAEUS THOMAS , SCHÜLLER HANS
Published: July 2006

To study the prevalence and significance of far‐field QRS complex sensing via unipolar atrial electrodes, we attempted to provoke this phenomenon postoperatively in 119 patients with DDD pacemakers. It occurred in 42 patients (35%), with different types of atrial electrodes. In 27 cases with documented far‐field QRS complex sensing, selection of an adequate atrial amplifier sensitivity eliminated the problem; in the remaining 15 cases, other program adjustments were necessary. In all patients DDD pacing could be maintained, and no reoperations were required. In a retrospective analysis of a subgroup of 26 patients, all having received endocardial unipolar carbon tip electrodes in the right atrial appendage, the possibility of predicting subsequent far‐field QRS complex sensing was studied. The occurrence thereof was not significantly related to patient age or sex, indication for pacing, or routinely obtained electrophysiological measurements. Potential far‐field QRS complex sensing via the atrial electrode is significantly common in patients with DDD pacemakers. Patient characteristics and intraoperatively measured intraatrial signal amplitudes are not useful in predicting the postoperative occurrence of the phenomenon. As a rule, it can be handled effectively by pulse generator reprogramming.
Swallowing‐Induced Tachycardia: Electrophysiologic and Pharmacologic Observations
Authors: GREENSPON ARNOLD J. , VOLOSIN KENT J.
Published: July 2006

A 38‐year‐old man developed palpitations after swallowing. Intracardiac recordings and esophageal manometry were obtained during episodes of swallowing‐induced tachycardia. These studies demonstrated that the site of origin of the tachycardia was the high right atrium and that the onset of the tachycardia occurred prior to the arrival of the peristaltic wave in the esophagus. Evaluation of the tachycardia revealed that the likely mechanism for the tachycardia was triggered automaticity. Autonomic blockade and other pharmacologic interventions failed to prevent episodes of tachycardia. Swallowing‐induced tachycardia is a rare disorder triggered by an undefined neural reflex arc.
Simultaneous Insulation Deterioration Associated with Side‐by‐Side Subclavian Placement of Two Polyurethane Leads
Authors: FYKE F. EARL
Published: July 2006

During implantation of a bipolar dual chamber pacing system, two polyurethane leads were placed side‐by‐side through a single left subclavian vein puncture. The costoclavicular space was restrictive at the insertion site, and binding of the leads in this region made positioning difficult. Eleven months later, although pacemaker function remained normal, deterioration of both leads' insulation was noted on routine chest roentgenogram. Sixteen months after implantation, both leads failed. Insertion of polyurethane leads through a tight costoclavicular region should be avoided as subsequent mechanical stressing of the insulation may result in delayed lead failure.
Long‐Term Follow‐Up of Patients with Sick Sinus Syndrome: A Comparison of Clinical Aspects Among Unpaced, Ventricular Inhibited Paced, and Physiologically Paced Groups
Authors: SASAKI YASUYUKI , SHIMOTORI MASAHIRO , AKAHANE KUNIO , YONEKURA HIROAKI , HIRANO KEN , ENDOH RYOHEI , KOIKE SEIICHI , KAWA SIGEYUKI , FURUTA SEIICHI , HOMMA TATSUJI
Published: July 2006

To analyze the prognosis of the sick sinus syndrome (SSS), we compared the clinical aspects among unpaced, ventricular paced, and physiologically paced patients who were followed over a long period. Unpaced intrinsic SSS was not always progressive and patients did not necessarily require permanent pacing. The incidence of concomitant AV conduction disturbance was 65.6% before pharmacologic autonomic block, (PAB), but this was significantly reduced to 31.7% after PAB. Follow‐up study of the physiologically paced groups revealed no development of either new or more than second degree AVB. The VVI group had significantly more complications (68%) than the physiologically paced groups, mainly chronic atrial fibrillation (36%) and thromboembolism (20%). In addition, cardiothoracic ratio (CTR) in the VVI group was significantly greater compared with that in the physiologic groups. Nine deaths occurred during the follow‐up period in the pacing groups, including six with VVI and three with physiologic pacing. In the VVI pacing group, heart failure and thromboembolism were most commonly the causes of death, while in the physiologic pacing groups, the causes of death were noncardiac. Although the survival rate in the ventricular paced group was not significantly different from that in the physiologic pacing groups, cardiac deaths were fewer in the latter group. Considering our clinical data, the decision to use ventricular pacing needs to be carefully weighed in patients with sick sinus syndrome, and physiologic pacing is more highly recommended. (PACE, Vol. 11. November 1988)
The Automatic Implantable Cardioverter Defibrillator: T Wave Sensing in the Newest Generation
Authors: SINGER IGOR , DE BORDE ROZANN , VELTRI ENRICO P. , SIDDOWAY LYLE A. , LEVINE JOSEPH H. , GRIFFITH LAWRENCE S.G. , GUARNIERI THOMAS
Published: July 2006

The AICD uses an automatic gain control amplifier for detecting the small electrograms during ventricular fibrillation. The latest generation of the AICD appears to have a more sensitive lock on gain amplifier, as 6 of 76 patients implanted with the new AICD had double counting of the QHS‐T wave complex resulting in asymptomatic discharges. Solutions to the problem of limiting these asymptomatic discharges are difficult and include slowing of the heart rate with beta blockers, changing the lead system, or replacement of the device. One of the six patients was treated with beta blockers. Three patients had their device changed, two patients requested the inactivation of their device until a rate programmable unit was available. The potential for T wave sensing in a lock on gain amplifier represents the unique dilemma between detecting small electrograms of ventricular fibrillation, and detecting diastolic events which occur shortly after the QRS complex.