bluuebunny/crossref_metadata_2025 huggingface dataset:
Two‐dimensional Echocardiographic Studies during Sustained Ventricular Tachycardia
Authors: ROSENBLOOM MARK , SAKSENA SANJEEV , NANDA NAVIN C. , ROGAL GARY , WERRES ROLAND
Published: July 2006

We evaluated left ventricular function in patients with recurrent sustained ventricular tachycardia (VT) using two‐dimensional echocardiography (2DE). Thirteen patients, 11 men and 2 women, age range 42–77 (mean 62 ± 12) years were studied in sinus rhythm (SR) and immediately after VT induction. 2DE parameters analyzed included wall motion, mitral valve leaflet motion, and ejection fraction (EF). In SR, 21 segments/walls in 12 patients showed wall motion abnormalities (WMA) ranging from hypokinesis to dyskinesis and one patient had generalized LV hypokinesis. In VT, new WMA were noted in 2 patients. Thirteen segments/walls in 8 patients showed further worsening of pre‐existing WMA. In 1 patient there was worsening of generalized LV hypokinesis. Three patients showed apparent improvement in pre‐existing WMA during VT. In 2 patients large apical aneurysms showed a reduction of dyskinesis in VT. Mitral valve opening was intermittent in patients with shorter VT cycle lengths and was maximal when atrial systole preceded or coincided with ventricular depolarization. Doppler echocardiography in 1 patient confirmed the pattern of intermittent mitral flow, with greatest flow occurring when mitral valve opening occurred well before the QRS peak. In 5 patients, 2DE permitted EF measurements. EF in SR ranged from 24–56% (mean 36 ± 13), decreased to 6–33% (mean 21 ± 11) within the first ten beats of VT and 6–25% (mean 19 ± 8) after twenty beats of VT. EF decreased more in patients with shorter VT cycles as compared to those with longer VT cycle lengths. We conclude: 1) 2DE is feasible during clinical electrophysiologic studies for sustained VT and may be a useful adjunct in studying the physiologic impact of VT; 2) WMA generally worsens during VT but can appear less evident due to declining systolic function in adjacent viable myocardium; 3) VT cycle length is a major determinant of hemodynamic compromise and atrial systole may contribute to cardiac output at slow VT rates.
Wide QRS Tachycardia: Multiple Mechanisms in a Patient after Myocardial Infarction
Authors: YEE RAYMOND , KLEIN GEORGE J.
Published: July 2006

A 34‐year‐old man was hospitalized for extensive antero‐apical myocardial infarction. Eight weeks after discharge from the hospital, he had intermittent rapid palpitations. During several episodes, a rapid, regular, wide‐QRS‐complex tachycardia with left bundle branch (LBB) morphology was recorded. All antiarrhythmic agents administered to the patient were unsuccessful in alleviating his symptoms, which were thought to be due to supraventricular tachycardia (SVT) with aberration. An electrophysiologic study was performed and revealed three morphologically distinct types of wide complex tachyarrhythmias: 1) Tachycardia 1 was determined to be A‐V re‐entry with antegrade conduction utilizing the normal A‐V conducting system and retrograde conduction over a concealed accessory pathway located in the left A‐V groove; 2) tachycardia 2 was identified as ventricular tachycardia (VT); and 3) tachycardia 3 was considered to be a second morphologic type of ventricular tachycardia as the morphology was identical to some of the episodes documented clinically. The patient was treated with oral amiodarone which was unsuccessful until combined with quinidine; this regimen has suppressed recurrence of VT during a four‐month period of follow‐up.

The occurrence of wide‐QRS‐complex tachycardia in this patient immediately suggested the diagnosis of VT, but our other findings were unexpected. This case illustrates the need for considering all possible mechanisms when seeking to manage tachyarrhythmias, even if the diagnosis appears obvious.
Long‐Term Follow‐up of Pulse Width Threshold of Transvenous and Myo‐epicardial Leads
Authors: HENGLEIN DAGMAR , GILLETTE PAUL C. , SHANNON CATHLEEN , BURNS GINA
Published: July 2006

Postoperative pulse width thresholds were measured at a constant of 5 volts in 140 patients. In 41 patients, transvenous atrial and/or ventricular leads were implanted at a median age of 13 years (3–78 yrs). Myo‐epicardial leads were implanted in 99 patients at a median age of 8 3/4 years (1 wk to 76 yrs). The initial rapid rise of threshold was found to persist not longer than to the third follow‐up period of 11 days to 5 weeks in all atrial and transvenous ventricular leads; in myo‐epicardial ventricular leads it persisted until the period of more than 5 weeks to 6 months. During initial rise, pulse width threshold m + sem did not exceed 0.45 ms. We therefore suggest that a pulse width setting of 0.5 ms at 5 V is a safe setting for this period. In only one patient did a late rise of threshold occur.

The comparison of pulse width thresholds of transvenous versus myo‐epicardial leads showed lower mean values for transvenous atrial leads in each follow‐up period, but the difference was not statistically significant. The pulse width thresholds of transvenous ventricular leads were significantly lower than those of myo‐epicardial leads in some follow‐up periods. We therefore conclude that transvenous leads have a slight advantage with regard to postoperative pulse width threshold.
Peripheral Migration of Pacemaker Electrodes
Authors: WIDMANN WARREN D. , EDOGA JOHN K. , GARFIAS DAVID , MCLEAN EDWARD R.
Published: July 2006

A 55‐year‐old male was admitted with right ileo‐femoral phlebitis caused by an unused pacemaker electrode fragment which had migrated from the right subclavian vein to the right iliac vein. Vena cava plication was followed by removal of the electrode fragment and complete resolution of the phlebitis. The exposed metal coil may have contributed to the severe inflammatory reaction.
Apparent Pacemaker Failure due to Reversion Circuitry within the Programming Device
Authors: HAYES DAVID L. , HOLMES DAVID R. , MERIDETH JOHN , OSBORN MICHAEL J. , BARDSLEY WILLIAM T.
Published: July 2006

While being evaluated for a recurrent tachyarrhythmia, a patient with a permanent pacemaker underwent reprogramming of the unit from the DVI to the VVI mode for assessment of the underlying rhythm. Subsequent reprogramming of the pacemaker to the DVI or DDD mode was impossible despite multiple attempts and the use of multiple programmers. The problem was considered to be a malfunction of the pacemaker circuitry, and plans were made for the pacemaker to be explanted and a replacement unit implanted. Before the procedure, the pacemaker company was notified of the explantation. We subsequently learned that a special programming sequence had to he carried out because of reversion circuitry present in the pacemaker but not described in the available literature. This report emphasizes the need for familiarity with each of the individual pacemakers being implanted and the need for the manufacturer to be as specific as possible given the complexity of current units.
Catheter‐induced A‐V Nodal Block Occurring during Electrophysiologic Study
Authors: PETERS ROBERT W. , NUSSBAUM STAN , MAILHOT JAMES , LIEF LAURENCE H. , PALEY HYMAN W.
Published: July 2006

We describe a patienl who underwent electrophysiologic study for evaluation of recurrent syncope. No abnormalities were found but high‐grade A‐V block proximal to the A‐V bundle depolarization developed abruptly as the coronary sinus electrode catheter was being withdrawn. The A‐V block disappeared gradually over a 12‐hour period, progressing to type I second‐degree A‐V block, and then to first‐degree A‐V block (due to prolonged A‐V nodal conduction), prior to resuming normal conduction. We postulate that A‐V block was induced by direct contact between the electrode catheter and the A‐V node or very proximal His bundle. Catheter‐induced A‐V block at this site has been described only rarely, possibly because of the relatively protected location and the configuration of the A‐V node.
Failure to Pace following High Dose Antiarrhythmic Therapy—Reversal with Isoproterenol
Authors: LEVICK CARL E. , MIZGALA HENRY F. , KERR CHARLES R.
Published: July 2006

A patient with resistant ventricular tachycardia treated with a combination of antiarrhythmic agents is described. Sudden onset of a wide complex ventricular rhythm with periods of asystole and failure to achieve transvenous pacing were observed, presumably due to antiarrhythmic drug toxicity. Inability to pace was reversed by the infusion of isoproterenol.
Tachycardia‐Termination Algorithm: A Valuable Feature for Interruption of Pacemaker‐mediated Tachycardia
Authors: van GELDER L.M. , el GAMAL M.I.H. , BAKER R. , SANDERS R.S.
Published: July 2006

A 45‐year‐old man who had been implanted with a VVI pacemaker for sinus arrest complained of syncope, dizziness and throbbing in the neck. His pacemaker Junction was normal, but during ventricular pacing, retrograde V‐A conduction was observed. This pacer was replaced by a DVI unit which caused periodic abdominal muscular contractions. We replaced this unit with an Intermedics Cosmos DDD‐M pacemaker. This type of pacemaker in‐a patient with V‐A conduction may cause pacemaker‐mediated tachycardia (PMT). However, the Cosmos has a tachycardia‐termination algorithm which detects continued pacing at the ventricular tracking rate, allows it to proceed for 15 consecutive pace events, and inhibits the 16th ventricular output pulse, thus breaking the reentry loop. The Cosmos pacer has a number of features to prevent initiation of PMT, and is also able to terminate the tachycardia when it occurs because of the tachycardia‐termination algorithm. This feature is valuable in DDD‐M pacemakers implanted in patients with V‐A conduction. Whether this algorithm will be effective in all cases remains to be determined.
Amaurosis Fugax in a Patient with a Left Ventricular Endocardial Pacemaker
Authors: SCHIAVONE WILLIAM A. , CASTLE LON W. , SALCEDO ERNESTO , GRAOR ROBERT
Published: July 2006

A transvenous left ventricular endocardial pacemaker catheter is a potential source of systemic arterial embolization. The case of a woman who presented with left‐eye amaurosis fugax is reported. The patient had a history of contralateral carotid atherosclerosis; however, the digital subtraction angiography of the carotid arteries was not sufficiently abnormal to account for her present symptoms. The patient had a history of two myocardial infarctions and the tachycardia‐bradycardia syndrome for which she was treated with a demand ventricular pacemaker. The chest x‐ray and electrocardiogram suggested pacemaker catheter malposition. By M‐mode und two‐dimensional echocardiography, the catheter was shown to cross the atrial septum and the mitral valve to implant in the left ventricular endocardium. The approach to diagnosis and therapy that led to surgical removal of the pacing catheter is presented. The causes of the electrocardiographic right bundle branch block pattern in cardiac pacing and the usefulness of echocardiography in evaluating pacing catheters are discussed.
Redundant Pacing: Case Report and Review
Authors: MORSE DRYUEN P. , TARJAN PETER , McNICHOLAS KATHLEEN W. , DelROSSI ANTHONY J. , LEMOLE GERALD M.
Published: July 2006

A 17‐year‐old boy with severe sick sinus bradycardia had a doubly redundant pacemaker inserted. With two separate ventricular leads inserted by the epicardial route, the pacemaker is able to compensate for a lead that has developed high threshold by activation of an alternate lead. The two pacing channels of the pulse generator can be programmed independently of one another. In addition, there is a back‐up pacing circuit separate from the two primary channels. The pacer can be used with both channels active for continuous automatic redundancy for safety, or with one channel active and the other in reserve.
Irregular Pacemaker Tachycardia in a Patient with WPW Syndrome and an A‐V Universal Pacemaker
Authors: WEHR MICHAEL , SCHMITT CLAUS‐G. , PETER J. HERMANN
Published: July 2006

We describe a case of an irregular pacemaker circus movement tachycardia in a patient with the Wolff‐Parkinson‐White syndrome and a normally functioning A‐V universal (DDD) pacemaker (Cordis Sequicor 233 D). The mechanism of the artificial circus movement tachycardia, which uses the pacemaker as the anterograde limb and a septally located accessory atrioventricular pathway as the retrograde limb, is discussed.
Simultaneous AV Nodal Reentrant and Ventricular Tachycardias
Authors: BELHASSEN BERNARD , PELLEG AMIR , PAREDES ABRAHAM , LANIADO SHLOMO
Published: July 2006

Simultaneous AV nodal reentrant and ventricular tachycardias were observed during the course of an electrophysiological study in a 51‐year‐old patient who suffered from recurrent attacks of sustained ventricular tachycardia. Occurrence of simultaneous tachycardias was facilitated by the fact that both tachycardias had a similar cycle length. Ventricular tachycardia was most probably initiated by AV nodal tachycardia previously induced by atrial extrastimulation following the administration of atropine.
Polymorphous Ventricular Tachycardia Associated with a Marked Prolongation of the Q‐T Interval Induced by Amiodarone
Authors: BHANDARI ANIL K. , QUOCK COLLIN , SUNG RUEY J.
Published: July 2006

We report the case of a patient who developed a life‐threatening polymorphous ventricular tachycardia (PVT) after six weeks of treatment with amiodarone. The Q‐T interval was markedly prolonged at 0.86 second. The drug induction of PVT was strongly suggested by the fact that PVT resolved four days after withdrawal of amiodarone when the Q‐T interval had shortened to 0.60 second; the arrhythmia has not recurred in the nine months of follow‐up since then. Amiodarone, though a very effective antiarrhythmic agent, may induce serious PVT.
Permanent Cardiac Pacing After Open‐heart Surgery: Acquired Heart Disease
Authors: GOLDMAN B.S. , HILL T.J. , WEISEL R.D. , SCULLY H.E. , MICKLEBOROUGH L.L. , PYM J. , BAIRD R.J.
Published: July 2006

Retrospective review of 5,942 patients who underwent open‐heart surgery for acquired heart disease revealed that 123 patients (2.1%) required permanent cardiac pacing postoperatively; 4.6% of these underwent predominantly valvular surgery and 0.6% had coronary bypass. The most important factors appeared to be: 1) preoperative evidence of a conduction disorder; 2) advanced patient age; 3) dense calcium in the aortic annulus; 4) valvular surgery and, especially, tricuspid valve surgery; and 5) poor myocardial protection. Postoperative permanent pacing had a considerable impact on patient morbidity from maintenance operations; most complications were lead‐related problems.
Syncope in the Wolff‐Parkinson‐White Syndrome: Incidence and Electrophysiologic Correlates
Authors: YEE RAYMOND , KLEIN GEORGE J.
Published: July 2006

Syncope in the patient with Wolff‐Parkinson‐White (WPW) syndrome raises the specter of rapid tachyarrhythmias and the possibility of sudden cardiac death. We reviewed the records of 55 consecutive WPW patients referred for electrophysiologic evaluation of known or suspected arrhythmias to determine the incidence and significance of syncope. Twelve patients (22.6%) reported the occurrence of at least one episode of syncope. In eleven (20%) of these, syncope was preceded by rapid palpitations. Forty‐three patients (77.4%) had no syncopal episodes. These two groups did not differ significantly with regard to age, sex, presence of associated cardiac or neurologic disease, drug history or accessory pathway location. There was no significant difference in cycle length of reciprocating tachycardia (syncope = 295.6 ± 59.8 vs non‐syncope = 334.5 ± 59.6 ms, p < .5), shortest R‐R intervals between preexcited beats (260 ± 78.6 vs 246.7 ± 55.4 ms, p < .5) and average R‐R interval (364.4 ± 37.9 vs 367.4 ± 77.5 ms, p < .5) measured during atrial fibrillation. The anterograde effective refractory period of the accessory pathway (292.1 ± 31.9 vs 299 ± 58.1 ms, p < .5) and the shortest cycle length with 1:1 conduction over the accessory pathway (306.7 ± 75 vs 289.1 ± 77.5 ms, p < .5) similarly did not differ. We conclude that syncope occurs in approximately 20% of patients with the Wolff‐Parkinson‐White syndrome referred for assessment of tachycardia. Patients with syncope do not have distinct clinical features or a more malignant electrophysiologic profile, suggesting that other extracardiac factors may play an important roe in the genesis of syncope in this group.
Sixteen Failures in a Single Model of Bipolar Polyurethane‐insulated Ventricular Pacing Lead: A 44‐Month Experience
Authors: HANSON JOHN S.
Published: July 2006

During a 44‐month period, 105 Medtronic model 6972‐58 polyurethane‐insulated, bipolar ventricular pacing leads were implanted, of which 16 failed clinically at a mean of 20.5 months post‐implant. Pacing dysfunction presented as either intermittent or complete loss of sensing and/or capture and, rarely, oversensing. Thirteen of the 16 patients were asymptomatic, and problems were detected in 11 instances during routine telephonic surveillance. At the time of lead replacement, low or widely fluctuating lead resistance values and high current drain were uniformly observed. The single lead capable of total extraction revealed rupture of both internal and external insulation. A brief summary of the currently much‐discussed “polyurethane controversy” is presented, and the issue of patient management is discussed.
Present Status of Clinical Electrophysiologic Studies: Introduction—What Studies Are Necessary
Authors: MICHELSON ERIC L. , DREIFUS LEONARD S.
Published: July 2006

Electrophysiologic testing represents a major advance in both the diagnosis and management of cardiac rhythm and conduction disturbances. It is a sophisticated but arduous and invasive technique that requires proper patient selection, trained personnel, and specialized equipment and facilities for its optimal application. Patients with serious or life‐threatening rhythm disorders are most likely to benefit from electrophysiologic testing. Patients with cardiovascular disease and incapacitating symptoms such as syncope or near‐syncope, for whom noninvasive testing fails to reveal an etiology, as well as those patients considered candidates for various pacemaker and antiarrhythmic surgical interventions, are also suitable candidates for electrophysiologic testing. This relatively young field is still rapidly evolving. The major advance to come in the field of electrophysiology will be the simple identification of patients at high risk for sudden cardiac death. It is unclear whether invasive electrophysiologic testing will ultimately fulfill this goal or whether it will be helpful instead in leading to the development of noninvasive methods which may satisfy this need. This symposium and the introductory article address the present status of electrophysiologic studies in clinical practice.
Response of an Abnormal Sinus Node to Intravenous Flecainide Acetate
Authors: HELLESTRAND KEVIN J. , NATHAN ANTHONY W. , BEXTON RODNEY S. , CAMM A. JOHN
Published: July 2006

A patient with sinus node disease underwent provocative testing with flecainide, a new Vaughan Williams class IC antiarrhythmic agent. There were dramatic increases in sinus node recovery times and in Sinoatrial conduction times, and the magnitude of the response could only be witnessed because of the emergence of a subsidiary junctional pacemaker without retrograde conduction to the atria.
Runaway Pacemaker Inhibited by External Overdrive Stimulation: A Case Report
Authors: BLUHM GÖSTA , SUNDSTEDT CARL‐DAVID
Published: July 2006

A case is described of runaway pacemaker (Stimulith) which could be inhibited by external chest‐wall overdrive. This pulse generator had been implanted for four years before runaway occurred; the runaway rate was 140/min with capture of the ventricles. Using external chest‐wall stimulation at a rate of 170/min, we were able to achieve almost complete inhibition of the faulty generator, while preparing for emergency replacement.
Cellular and Tissue Responses to Recurrent Ventricular Tachycardia and Fibrillation
Authors: HOFFMAN BRIAN F.
Published: July 2006

The effects of rapid rhythms on cellular electrical activity depend on the rate of the rhythm, the cell type, and its condition prior to the arrhythmia. Rapid rates can cause major changes in transmembrane ion concentration gradients and the magnitude of these is a function of the transport capacity of the sodium‐potassium pump. Thus digitalis can be expected to exert a prominent effect on rate‐induced changes. Some of the rate‐induced changes can lead to the generation of arrhythmias, as through calcium overload and the development of delayed afterdepolarizations. Since the actions of antiarrhythmic drugs often show use‐dependence, the presence in the heart of local anesthetics or certain slow channel blockers will further modify the effect of rapid and irregular rhythms on cellular electrical activity.
Early Identification of Patients Who May Require Electrical Control Treatment
Authors: MOSS ARTHUR J.
Published: July 2006

Patients who are at increased risk of sudden death generally have significant underlying organic heart disease, but this is not always the case. The majority of patients at risk include those with the idiopathic long QT syndrome, the Wolff‐Parkinson‐White disorder, mitral valve prolapse, coronary heart disease, and cardiomyopathy. A history of syncope or presyncope and/or frequent or repetitive runs of ventricular ectopic beats are common prodromal findings in patients with a potentially life‐threatening problem. Potential candidates for implantable antiarrhythmic devices include high‐risk patients in whom an effective antiarrhythmic agent cannot be identified or those who cannot tolerate indicated antiarrhythmic agents because of adverse side effects.
Selection of Patients with Recurrence of Ventricular Tachyarrhythmias for Electrical Studies
Authors: HOROWITZ LEONARD N. , SPIELMAN SCOTT R. , GREENSPAN ALLAN M. , WEBB CHARLES R.
Published: July 2006

Clinical cardiac electrophysiologic testing has been employed in the evaluation and treatment of patients with tachyarrhythmias. In patients with recurrent supraventricular tachyarrhythmias, electrophysiologic study is indicated when the arrhythmia is life‐threatening or significantly disruptive to lifestyle, when empiric therapy has failed to control the arrhythmia, or when supraventricular tachycardia complicates the Wolff‐Piarkinson‐White syndrome. In patients with ventricular tachyarrhythmias, electrophysiologic study should be undertaken when life‐threatening sustained ventricular tachyarrhythmias are documented or where a substantial risk of developing these arrhythmias is noted.
Pathophysiology of Ventricular Tachyarrhythmias Amenable to Electric Control
Authors: REID PHILIP R. , MOWER MORTON M. , MIROWSKI M.
Published: July 2006

Technical advances now permit permanent implantation of devices such as antitachycardia pacemakers, cardioverters and cardioverter‐defibrillators for control of ventricular tachyarrhythmias. Despite the fact that these devices have been implanted only in patients resistant to conventional medical and surgical management, their effectiveness has been very encouraging. While improved designs are anticipated, preliminary studies have clearly indicated that one of the major challenges for successful clinical use will be appropriate interfacing of the device with the pathophysiology of the patient. Failure to recognize this fact will likely lead to unsuccessful clinical application. Moreover, these new instruments appear to be complementary to, rather than a replacement for, existing medical and surgical approaches to the patient with life‐threatening ventricular tachyarrhythmias.
Electrical Termination of Tachyarrhythmias by Discrete Pulses
Authors: GERMAN LAWRENCE D. , STRAUSS HAROLD C.
Published: July 2006

Reentrant tachycardias can often be terminated by discrete pacing stimuli that penetrate the reentrant circuit. The ability of discrete stimuli to terminate an arrhythmia depends on the timing of the stimulus, the distance from the site of reentry where the stimulus is applied, the electrophysiologic properties of the myocardium between the site of stimulation and the site of reentry, and the size of the reentrant circuit.

Modes of pacing used to terminate tachycardia have included single or multiple timed extrastimuli, overdrive pacing, burst pacing and competitive asynchronous (underdrive) pacing. Patient‐triggered devices that deliver asynchronous pacing stimuli are routinely available. Newer devices have been developed that automatically sense the onset of tachycardia and respond with pacing stimuli. These devices have been highly effective in selected patients with supraventricular tachycardia. The seriousness of occasional pacing‐induced acceleration of ventricular tachycardia or conversion to ventricular fibrillation has limited the application of these devices in patients with ventricular arrhythmias. Pre‐implantations electrophysiologic studies are necessary to document arrhythmia mechanisms and to determine the feasibility of various pacing modalities in treating the tachycardia. The potential for complicating arrhythmias (atrial fibrillation/flutter or ventricular fibrillation) must also be tested.

Future devices designed for terminating tachycardias with discrete pulses should be capable of being programmed to respond with one or more of the various modalities available. These devices should automatically and reliably sense both tachycardia onset and termination, and should adjust their responses appropriately if initial stimulation sequences fail to terminate the arrhythmia.
Synchronous Intracardiac Cardioversion
Authors: ZIPES DOUGLAS P. , HEGER JAMES J. , MILES WILLIAM M. , PRYSTOWSKY ERIC N.
Published: July 2006

The concept of synchronous transvenous cardioversion of sustained ventricular tachycardia is discussed. This article reviews the animal experience, initial and collective studies in patients, and results of permanent implantation in two patients.
Implantation Techniques of Antitachycardia Devices
Authors: FURMAN SEYMOUR , BRODMAN RICHARD , PANNIZZO FRANK , FISHER JOHN D.
Published: July 2006

Implantation of a defibrillator may be by a mixed technique of transvenous leads and subcostal thoracotomy. An alternative approach is placement of all defibrillator leads and possible pacemaker leads via median sternotomy. All sensing leads, either for a defibrillator or a pacemaker, should be bipolar to provide maximal rejection of interference signals. Interpretation of the electrogram requires analysis of the pathologic electrogram to distinguish it from the “normal” electrogram for that patient and may require several leads to determine the activation sequence; which will allow diagnosis of a tachycardia in a fashion similar to that performed by a human observer.
Potential Hazards of Implanted Devices for the Electrical Control of Tachyarrhythmias
Authors: ECHT DEBRA S.
Published: July 2006

Sensing difficulties are more common with antitachycardia devices employing atrial rather than ventricular leads, but the consequences are potentially more disastrous with ventricular leads. The problem may be magnified in that the spurious discharge from poor sensing is likely lobe asynchronous. Worsening of arrhythmias during termination attempts cannot be totally avoided, but may be minimized if caution and expertise are applied to selection and testing. A device which can reliably terminate a tachyarrhythmia accelerated by a termination attempt is the safest.
A Registry for Implantable Antitachycardia Devices
Authors: FURMAN SEYMOUR
Published: July 2006

Antitachycardia electrical stimulation involves significant problems of sensing the cardiac rhythm and determining whether a tachycardia exists. The simple algorithms developed for bradycardia pacing are inadequate for tachycardia pacing. Electrogram signal analysis and cardiac activation analysis with at least two leads will be required to make a device diagnosis of a tachycardia. Termination of a tachycardia reliably and consistently is difficult and has been accomplished reliably only by defibrillation. Further development of devices which are multimodal in termination capability is necessary. A registry for tachycardias and for tachycardia management is required to provide concentrated and analyzable data from a modality as yet infrequently used.
The Incidence of Retrograde Conduction in Children
Authors: BINK‐BOELKENS MARGREET Th.E. , ROSS BERTRAND A. , GILLETTE PAUL C. , SHANNON CATHLEEN , ZINNER ALEX
Published: July 2006

With the increasing use of “physiological” Pacemakers in the pediatric age group, retrograde conduction in children has become of clinical importance. Pacemaker which sense atrial depolarization may sense “retrograde” P waves. The pacemaker may then act as the antegrade limb of a reciprocating tachycardia circuit. While the patient's own conduction system act the retrograde limb. We reviewed the data of 127 patients who underwent antegrade and retrograde electrophysiologic study at Taxes Children's Hospital, with regard A‐V node; the incidence of retrograde conduction in patients after surgical correction of a tetralogy of Fallot was singnificantly lower (33%). None of the patients with third degree A‐V block had retrograde conduction. The mean retrograde conduction time was 162 ms (range 70‐335 ms) at the slowest pacing rate and 257 ms (range 80‐475 ms) at the fastest pacing rate. This high incidence of retrograde conduction and the variability of conduction times must be taken into when “physiological” pacemaker are to be implanted.
Treatment of Life‐threatening Ventricular Arrhythmias by a Combination of Antiarrhythmic Drugs and Right Ventricular Pacing
Authors: ECTOR H. , VAN BRABANDT H. , DE GEEST H.
Published: July 2006

Thirteen patients with intractable ventricular arrhythmias were studied; they underwent long‐term treatment by a combination of antiarrhythmic drugs and ventricular pacing. Eleven patients had a history of tachycardia and two had torsade de pointes; eleven of thirteen had had cardioversion and/or defibrillation. Prior to permanent pacemaker implantation, temporary pacing in the VVI mode was used in combination with one or more of the following drugs: amiodarone, aprindine, digitalis, metoprolol, mexiletine, procainamide, pindolol, propranolol, or quinidine. Various pacing rates were tried; when permanent pacing was instituted, a unipolar system which was at least rate‐programmable was used. Right ventricular VVI pacing, combined with drug therapy, was successful in ten of thirteen patients. Five of the ten patients are alive and free of arrhythmias after 78, 72, 72, 54, and 11 months, respectively. Although five patients died (after 60, 48, 30, 24, and 9 months, respectively), none of the deaths were related to arrhythmias. We suggest that in patients with ventricular arrhythmias refractory to conventional treatment, a therapeutic trial of right ventricular VVI pacing in combination with a drug regimen be used.
Occurrence and Significance of Arrhythmias Associated with Atrial‐Triggered Ventricular Pacing
Authors: LEVANDER‐LINDGREN MAJ , PEHRSSON S. KENNETH
Published: July 2006

A review of electrocardiograms from 85 patients with atrial‐triggered ventricular pacing [VAT, VDD, DDD] showed that various disturbances of rhythm were relatively cammon, and that the effects of an arrhythmia could be aggravated by this type of pacing. In certain circumstances even potentially dangerous ventricular extrasystoles were induced by the pacemaker. Abnormal triggering, sometimes with regular sinus rhythm, could also induce tachycardia. Our observations provided indications for a pacemaker design that would avoid such disturbing effects. The best available pacer for atrial‐triggered ventricular pacing is the programmable DDD type.
Multiple Anterograde and Retrograde AV Nodal Pathways: Demonstration by Multiple Discontinuities in the AV Nodal Conduction Curves and Echo Time Intervals
Authors: KUCK KARL‐HEINZ , KUCH BELA , BLEIFELD WALTER
Published: July 2006

Programmed electrical cardiac stimulation was performed in a 40‐year‐old man with documented recurrent, sustained ventricular tachycardia which was refractory to standard medical therapy. Both the presence of several discontinuities in the AV nodal conduction curves during atrial and ventricular stimulation and the time intervals of the AV nodal echo phenomena suggested the presence of multiple AV nodal pathways. The results of this study are of interest in further increasing our understanding of the electrophysiologic behavior of the human AV node.
A Theoretical Right Atrial Pressure Feedback Heart Rate Control System to Restore Physiologic Control to the Rate‐limited Heart
Authors: COHEN TODD J.
Published: July 2006

Physiologic control of heart rate may be limited by sinus node injury or congenital conduction defects. Control theory may be applied to restore physiologic rate control. Mean right atrial pressure is a likely candidate for incorporation into an artificial control system because of its: (1) stability at rest; (2) tendency to increase during exertion in the rate‐limited heart; (3) ability to decrease with increasing heart rate in the rate‐limited heart; and (4) accessibility for measurement via the transvenous route. A theoretical right atrial pressure feedback heart rate control system is presented; applications to physiologic pacing of patients with sick sinus syndrome, rate control of the transplanted heart, and pump frequency control of the total artificial heart are discussed.
Clinical Instrumentation for the Intra‐operative Mapping of Ventricular Arrhythmias
Authors: PARSON IAN , DOWNAR EUGENE
Published: July 2006

Surgical treatment of ventricular arrhythmias has been greatly facilitated by intra‐operative mapping. Present clinical mapping techniques are time‐consuming, of limited accuracy, and are restricted to monoform sustained tachycardias. A previously reported on‐line cardiac mapping system used in the research laboratory has been modified to provide epicardial maps of ventricular arrhythmias induced at the time of surgery. Changes such as a battery‐operated multiplexer, patient electrical isolation, adjustable electrogram gain, time‐code labeling and marker‐matrix display, have all contributed to the intra‐operative application of the original analog real‐time mapping technique. These modifications were accomplished without compromising the spatial or temporal resolution (0.5 cm and 8.3 ms) of the laboratory system. An advantage of the present system is a decrease in cardiopulmonary bypass time as a direct result of the instantaneous analysis and display of epicardial activation information. In addition, it enables, for the first time, short salvos and polymorphic runs of ventricular tachycardia to be mapped intra‐operatively.
Clinical Problems in Atrial Synchronous Ventricular Inhibited Pacing: A Long‐term Follow‐up of 54 Patients
Authors: KRISTENSSON BO‐ERIK , KRUSE IB , RYDÉN LARS
Published: July 2006

Fifty‐four VDD‐paced patients were followed for more than 12 months; they were studied retrospectively in order to assess possible clinical problems and their management. The patients were between 19 and 84 years of age (mean, 66 ± 11). Twenty‐four of the 54 received a VDD pacemaker as a primary implant and 30 had had VVI pacemakers which were changed to VDD mainly because of limited exercise tolerance or symptoms of AV asynchrony. The follow‐up time was between 12 and 69 months (mean, 39 ± 17). Pacemaker and lead problems were neither frequent nor serious. Six patients had spontaneous paroxysmal supraventricular tachyarrhythmias, four had pacemaker‐mediated supraventricular tachycardias and six had ventricular tachyarrhythmias. Treatment of tachyarrhythmias included drugs, DC conversion, reprogramming, or combinations of these measures. Frequency of hospitalization was not greater than expected. In conclusion, VDD pacing appears safe und reliable, with problems mainly associated with the underlying cardiac disease rather than to the pacing mode itself.
Pacemaker Treatment in Familial Amyloidosis with Polyneuropathy
Authors: ERIKSSON PETER , OLOFSSON BERT‐OVE
Published: July 2006

Involvement of the heart is common in familial amyloidosis with polyneuropathy (FAP) and is manifested by disturbances of atrioventricular and intraventricular conduction and dysfunction of the sinus node. Pacemaker implantation was performed in 20 patients with FAP in northern Sweden between 1968 and 1983 for the following indications: complete heart block (11), second degree heart block (1), sinus node dysfunction (5), and atrial fibrillation with a slow ventricular rate (3). There was a prompt improvement of symptoms attributable to a slow heart rate. Dislodgement of the electrode occurred in four patients; no other serious complications were observed. From our experience we conclude that at least one out of ten patients with FAP will eventually require pacemaker treatment. Cardiac pacing is an effective adjunct in the symptomatic treatment of FAP, although the ultimate prognosis depends mainly on the underlying disease.
Rapid Ventricular Tachycardia Due to His‐Purkinje Reentry
Authors: WALTER PAUL F. , POLLAK SCOTT
Published: July 2006

Two patients developed rapid His‐Purkinje reentrant tachycardia during programmed ventricular stimulation for evaluation of recurrent ventricular tachycardia. In Patient 1, His‐Purkinje reentry induced a morphologically distinct ventricular tachycardia which may have been a reentrant circuit operating independently for several cardiac cycles. His‐Purkinje reentry was not inducible in Patient 2 until lidocaine was given. Following lidocaine administration, sustained His‐Purkinje reentrant tachycardia was initiated by 2 premature ventricular stimuli. The tachycardia was rapid (240 beats per minute) and required cardio‐version.
Diagnostic Assessment of Recurrent Syncope
Authors: SHARMA ARJUN D. , KLEIN GEORGE J. , MILSTEIN SIMON
Published: July 2006

The definitive diagnosis of a cardiac arrhythmia as the basis for syncope is made by electrocardiographic monitoring during a syncopal episode. In the absence of this evidence, abnormalities demonstrated by an electrophysiologic study may suggest the etiology of syncope. Cardiac electrophysiologic testing in patients with recurrent syncope should probably be limited to patients with underlying cardiac disease. These patients are at a higher risk for sudden death and have a high incidence of electrophysiologic abnormalities. In particular, ventricular tachycardia may be evoked and specific therapy for this abnormality is associated with remission of syncope. In contrast, electrophysiologic studies in patients with no underlying cardiac disease have a very low yield of abnormal findings in the order of 10–20%, and should be performed only when there are reasons to suspect the presence of arrhythmias. Furthermore, in patients with no underlying cardiovascular disease there is a high spontaneous remission rate of syncope and the late incidence of sudden death is low, and related to the presence of other systemic illnesses. At present, the significance of nonsustained ventricular tachycardia or ventricular fibrillation induced during cardiac electrophysiologic studies in patients with no documented arrhythmias is unknown, and further prospective studies are necessary to define appropriate therapy for these patients. Further investigation is also required to clarify the spontaneous remission rate of syncope, as this information is of vital importance in assessing the success of any therapeutic modality.
Prevalence and Significance of Ventriculoatrial Conduction
Authors: WESTVEER DOUGLAS C. , STEWART JAMES R. , GOODFLEISH ROBERT , GORDON SEYMOUR , TIMMIS GERALD C.
Published: July 2006

Because retrograde atrioventricular conduction may predispose to pacemaker‐induced tachycardia when DDD pacing is employed, we assessed ventriculo‐atrial conduction in 117 patients undergoing electrophysiologic studies. Ventriculo‐atrial conduction was present in 40% with a mean (±sem) conduction time of 205 ± 12 ms. The maximum VA conduction time following minimum extrastimulus intervals averaged 258 ± 14 ms. Antegrade AV nodal properties predicted VA conduction in only 67% by using stepwise discriminant analysis. Only the PR interval, AH interval, and AV nodal effective refractory periods were helpful in predicting ventriculo‐atrial conduction. Although ventriculo‐atrial conduction time increased on most antiarrhythmic drugs, it was infrequently eliminated.
A Rate‐responsive Pacemaker Controlled by Right Ventricular Blood Temperature
Authors: JOLGREN DAVID , FEARNOT NEAL , GEDDES LESLIE
Published: July 2006

To demonstrate the capabilities of a rate‐responsive pacemaker controlled by right ventricular blood temperature, a prototype pacemaker was developed and tested in dogs with complete atrioventricular (AV) block. Using a previously obtained data base of right ventricular blood temperature recorded both during rest and during treadmill exercise from dogs with either induced AV block or normal AV conduction, a control algorithm which identified periods of exercise was developed. This algorithm was implemented in a microprocessor‐based, rate‐responsive pacemaker which generates two pacing rates: a basal rate (86 bpm) during rest and a higher rate (113 bpm) during moderate exercise. With repeated trials of submaximal treadmill exercise (2.25, 3.0, 5.0 mph, 16% grade) the pacemaker correctly detected the onset and cessation of exercise with latencies ranging from 35 to 124 seconds. Pacemaker rate increase latency decreased as the exercise level was increased. Pacemaker response latency was not affected by the choice of resting or exercise pacing rate. These preliminary data indicate that right ventricular blood temperature can provide a reliable index to control pacemaker rate. An implantable temperature‐controlled pacemaker using this algorithm is presently under long‐term evaluation in dogs performing untethered exercise.
Pacemaker Headaches
Authors: DAS GOPAL
Published: July 2006

A symptom complex (Pacemaker syndrome) consisting of hypotension, dizziness, or near‐syncope in patients with functioning ventricular pacemakers has been previously described. Whereas, the effects of synchronized ventriculo‐atrial contraction on forward systemic circulation are known, the effects of increased venous dynamics on systemic function are not known. We describe a patient who developed severe headaches during periods of ventricular pacing with retrograde ventriculo‐atrial conduction. These headaches occurred in the absence of symptoms of Pacemaker syndrome or of changes in systemic blood pressure. We believe that the headaches were caused by alterations in intracranial pressure from exaggerated pulsatile venous dynamics. Conversion of the pacing system from VVI to AV sequential pacing completely relieved the headaches.
Experience with a New Epimyocardial Pacing Lead in Children
Authors: MICHALIK RICHARD E. , WILLIAMS WILLIS H. , ZORN‐CHELTON SUSAN , HATCHER CHARLES R.
Published: July 2006

A new permanent epimyocardial Medtronic 4951 “stab‐in” or “fishhook” pacing electrode was implanted in 16 children. Identical technique, with particular attention to the direction of the coronary circulation, was utilized to implant the leads. There were 10 atrial implantations (5 active, 5 redundant) and 18 ventricular implantations (15 active, 3 redundant). Pacing modes were VVI (12), VDD (1), DVI (2), and DDD (1).

Experience with the lead covers 280 patient months (3 days to 21.8 months, mean 14 months). Patients were allowed monthly via telephonic transmission. With the exception of the single patient who expired three days after implantation, each patient has returned for follow‐up analysis including chronic threshold determinations using the programming capabilities of the pulse generators. Only one lead required more than the minimum obtainable voltage output from the pulse generator to effect capture. No other lead required more than 5.0 volts at 0.5 ms pulse width. There have been no lead fractures or dislodgements.

In this evaluation the Medtronic 4951 lead performed well in both atrium and ventricle in a group of children with diverse cardiac pathology. The small diameter of the lead and the low profile of the electrode are advantageous for use in pediatric patients.
Paroxysmal Complete Heart Block due to Bradycardia‐dependent, “Phase 4” Fascicular Block in a Patient with Sinus Node Dysfunction and Bifascicular Block
Authors: BERGFELDT LENNART , VALLIN HANS , EDHAG OLOF , HERRLIN BO , LAGERGREN HANS
Published: July 2006

A 34‐year Old man with ankylosing spondylitis was admitted to the hospital because of syncopal attacks and heart block. Standard ECG, telemetry and an invasive electrophysiologic examination demonstrated right bundle branch block with left anterior fascicular block, sinus node dysfunction with spontaneous slowing of the sinus rate and, as a result, complete infrahisian atrioventricular block in the remaining fascicle at sinus rates below 57 beats per minute. Infrequent supraventricular extrasystoles and abruptly terminated atrial pacing led to the same result. Atrioventricular conduction resumed after three‐to‐four blocked atrial impulses with successively increasing rate. Pacemaker treatment provided complete symptomatic relief.
Antibiotic Prophylaxis for Pacemaker Implantation: A Prospective Randomized Trial
Authors: RAMSDALE DAVID R. , CHARLES RICHARD G. , ROWLANDS DAI B. , SINGH SATISH S. , GAUTAM PRASANNA C. , FARAGHER ERIC B.
Published: July 2006

Prophylactic antibiotics are frequently prescribed for patients undergoing permanent pacemaker implantation even though data confirming their effectiveness are limited. Five hundred patients requiring elective permanent pacemaker implantation or generator replacement were prospectively randomized either to receive or not receive prophylactic antibiotic treatment at the time of implantation. The implantation site was treated with 10% povidone‐iodine solution and 0.5% alcoholic chlorhexidine preoperatively. The wounds were inspected for evidence of infection at 3 days and 1, 3, 6 and 12 months postimplantation. Three patients (two receiving prophylactic antibiotics and one no antibiotics) developed pacemaker pocket infection; Staphylococcus aureus was the pathogenic organism in each case (P = 0.56). Eighteen patients developed clinical evidence of superficial wound inflammation requiring antibiotic treatment but not pacemaker removal. Six had received prophylactic antibiotics and 12 had not (P = 0.27). We conclude that pacemaker pocket infection is unusual with careful preoperative skin preparation and close postoperative follow‐up. Under these circumstances prophylactic antibiotic treatment is of no practical value.