bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Event Markers During Exercise Testing to Optimize Morphology Criterion Programming of Implantable Defibrillator
Authors: MARTIN DAVID , Jr. VENDITTI FERDINAND J.
Published: July 2006

The present generation implantable defibrillator introduced on‐line event markers that can be used to evaluate tachycardia detection in the electrophysiological testing mode. These markers were used to assess the appropriateness of programming the morphology criterion for detection of ventricular tachycardia. Twenty‐one consecutive patients (19 men, 2 women) performed 29 bicycle exercise tests with real‐time recording of the electrocardiogram and the event markers on a multichannel recorder. Mean ejection fraction was 29% (range 15%‐69%). Seven patients were taking anfiarrhythmic agents. Twelve patients satisfied the morphology criterion at rest (n = 1) or during exercise (group I), and nine patients did not (group II). One patient was excluded from analysis because of continuous ventricular pacing. Mean peak heart rate was 130 beats/min in group I and 125 beats/min in group II. No statistical differences existed between the groups in relation to cycle length of ventricular tachycardia and mode of induction of arrhythmia, QRS duration on the electrocardiogram, during native rhythm, amplitude and duration of defibrillation patch R wave, calculated duty cycle at peak heart rate, and number of discharges of the automatic implantable cardioverter defibrillator at 2 to 14 months of follow‐up time. It is concluded that clinical, electrocardiographic, and implantation data are unreliable in predicting satisfaction of the morphology criterion during high heart rates in native rhythm. Formal exercise testing in the electrophysiological mode enables a rational decision to be made about the appropriateness of the use of probability density function in each patient.
Right Atrial Diverticulum Presenting as Wolff‐Parkinson‐White Syndrome
Authors: CAMPBELL ROBERT M. , PARKS W. JAMES , CRAWFORD FRED A. , GILLETTE PAUL C.
Published: July 2006

A 7‐year‐old maJe presenting with Wolff‐Parkinson‐White syndrome and tachycardia was suspected by echocardiographic and magnetic resonance imaging evaluation to have an associated pericardial cyst anterior to the right atrium and ventricle. Electrophysiological evaluation demonstrated short antegrade and retrograde accessory connection refractory periods, with inducible orthodromic atrioventricular reentranf tachycardia. Surgical observation revealed a rare congenital right atrial diverticulum bridging the anterior right atrioventricular groove, with the functional accessory connection lateralized to the medial aspect of this structure. Endocardial and epicardial incisions and cryolesions placed along the anterior right atrioventricular groove initially appeared successful, but preexcitation recurred within 4 weeks postoperatively.
Coronary Air Embolism Complicating Transseptal Radiofrequency Ablation of Left Free‐Wall Accessory Pathways
Authors: LESH MICHAEL D. , COGGINS DWAIN L. , PORTS THOMAS A.
Published: July 2006

Radiofrequency catheter ablation is an important new technique for curing patients with accessory pathway‐mediated tachycardia. Ablation of left free‐wall accessory pathways may. be accomplished either by a retrograde, transarterial approach or via a transseptal approach using a long vascular sheath. We describe air embolization into the coronary artery as a complication of the transseptal approach, which was temporally associated with catheter exchange. While here were no permanent adverse sequelae, this report emphasizes the need /or scrupulous attention to the possible insinuation of air during procedures involving long vascular sheaths across the atrial septum. To prevent air embolism, we recommend slow removal of the ablation catheter along with continuous flushing with heparinized saline during exchanges.
Significance of Ventricular Pacing Site in Manifest Entrainment During Orthodromic Atrioventricular Reentrant Tachycardia with Left‐Sided Accessory Pathway
Authors: SUYAMA KAZUHIRO , OHE TOHRU , KURITA TAKASHI , MARUYAMA TAKAHISA , TAKAKI HIROSHI , AIHARA NAOHIKO , KAMAKURA SHIRO , SHIMIZU WATARU , MATSUHISA MOKUO , SHIMOMURA KATSURO
Published: July 2006

We examined enfrainment by ventricular pacing in six patients during orthodromic atrioventricular reentrant tachycardia (AVRT) utilizing a left‐sided lateral accessory pathway. Constant fusion and progressive fusion were demonstrated in all patients by left ventricular pacing during tachycardia, but in none of the patients by right ventricular pacing. When left ventricular pacing was performed during AVRT, the antidromic wave front from the pacing impulse (n) collided with the orthodromic wave front of the previous pacing beat (n ‐ 1) within the ventricle, therefore, constant fusion and progressive fusion were demonstrated in the surface electrocardiographic QRS complexes. On the other hand, when right ventricular pacing was performed during orthodromic AVRT, the antidromic wave front from the pacing impulse (n) collided with the orthodromic wave front of the previous paced beat (n ‐ 1) within the normal atrioventricular pathway, and constant fusion and progressive fusion were therefore not demonstrated. These phenomena were explained by the relationship of the ventricular pacing site and the reentrant circuit. This study demonstrates the importance of the pacing site in manifest entrainment of orthodromic AVRT during ventricular pacing.
Driving Restrictions Advised by Midwestern Cardiologists Implanting Cardioverter Defibrillators: Present Practices, Criteria Utilized, and Compatibility with Existing State Laws
Authors: DICARLO LORENZO A. , WINSTON STUART A. , HONOWAY SUSAN , REED PATRICIA
Published: July 2006

Although some patients remain at risk of losing physical control or collapsing after implantation of a cardioverter defibrillator for sustained ventricular arrhythmias, little is known about restrictions advised by arrhythmia specialists to patients with implanted devices concerning physical activities such as driving. In this study, all of the 58 cardiologists implanting cardioverter defibrillators in three contiguous midwestern states were surveyed to determine present practices and the compatibility of these practices with existing state law. Of the 51 respondents (88%), 27 cardiologists (53%) advised only those implanted patients who had had arrhythmia‐induced presyncope or physical collapse to cease driving. Twenty two of the remaining cardiologists (43%) advised all implanted patients to cease driving, whereas two cardiologists (4%) never advised any implanted patient to restrict driving. Permanent driving abstinence was advised by seven of the responding cardiologists (14%), while temporary driving abstinence for periods of 2–12 months (mean 6 ± 3 months) was recommended by the remaining 42 respondents (82%) who advised against driving. The criteria utilized, driving restrictions advised, and durations advised for driving restrictions were not uniform in any of the 13 surveyed university and nonaffiliated cardiology practices with ≥ 2 implanting cardiologists. Overall, 38 cardiologists (74%) advised against driving and recommended durations that equaled or exceed their state's minimum legal requirements, although only 27 of the 51 cardiologists (53%) based their practice upon knowledge of their state's driving laws. The results of this survey suggest that the majority of cardiologists who implant cardioverter defibrillators advise their patients against driving postoperatively. However, the criteria and durations utilized in advising driving abstinence are not uniform and do not always conform with existing state laws.
Direct Current Application: Easy Induction of Ventricular Fibrillation for the Determination of the Defibrillation Threshold in Patients with Implantable Cardioverter Defibrillators
Authors: WEISMÜLLER PETER , RICHTER PETER , BINNER LUDWIG , GROSSMANN GEORG , HEMMER WOLFGANG , HÖHER MARTIN , KOCHS MATTHIAS , HOMBACH VINZENZ
Published: July 2006

For the determination of the defibrillation threshold, the induction of ventricular fibrillation is mandatory. However, in severely damaged hearts it is sometimes difficult to induce ventricular fibrillation by rapid stimulation or alternating current. Only rapid nonclinical ventricular tachycardias may result, and their cardioversion threshold may be different from the defibrillation threshold. Therefore, it was the purpose of this study to test the potential of direct current (DC) application to rapidly induce ventricular fibrillation in patients with an implanted Cardioverter defibrillator. The defibrillation threshold had to be determined in 13 patients (9 with coronary heart disease, 4 with dilative cardiomyopathy, ejection fraction 35%) during and 2 weeks after the implantation of a Cardioverter defibrillator. DC was applied 37 times by a commercially available 9‐V DC battery via a bipolar catheter for about 3 seconds. Ventricular fibrillation was induced 23 times (62%) and rapid nonclinical ventricular tachycardias were induced six times (16%). In one patient clinical ventricular tachycardia was observed. In seven instances (19%) sinus rhythm remained. In 12 of the 13 patients, ventricular fibrillation could be induced by DC. Thus, the induction of ventricular fibrillation by DC application may serve as an additional tool to induce ventricular fibrillation, determining the defibrillation threshold in implantable Cardioverter defibrillator patients.
Transtelephonic Interrogation of the Implantable Cardioverter Defibrillator
Authors: ANDERSON MARK H. , PAUL VINCE E. , JONES SUE , WARD DAVID E. , CAMM A. JOHN
Published: July 2006

Third generation implantable Cardioverter defibrillators (ICDs) have extensive memory capability to store data about the patient's arrhythmias and the effect of therapies delivered by the ICD. However, this data has so far been accessible only when the patient attends the pacing clinic. Two Medtronic 9421 PCD(tm) TeletraceR transmitters have been used to interrogate Medtronic 7216A and 7217B PCD(tm)s at distances of up to 300 miles from our hospital and transmit the data to a 9420 PCD(tm) TeletraceR receiver. Successful transmission of data has been obtained on 50 occasions with 100% data concordance with repeat transmission. The system can reduce the number of unscheduled clinic visits, reduce delay in making a diagnosis following unexpected delivery of a shock therapy, and reassure patients about to be discharged following ICD implantation. The benefits are magnified where patients reside far away from the implanting center.
Comparison of Isoproterenol and Exercise Tests in Asymptomatic Subjects with Wolff‐Parkinson‐White Syndrome
Authors: CHIMIENTI MARCELLO , BERGOLIS MARIA LI , MOIZI MAURIZIO , KLERSY CATHERINE , NEGRONI MARIA S. , SALERNO JORGE A.
Published: July 2006

In order to evaluate the effects of increases of sympathetic tone in ventricular response during atrial fibrillation and in the relationship between the accessory pathway effective refractory period (ERP) and ventricular rate during atria] fibrillation, 20 male subjects, aged 19 ± 6 years, were studied electrophysiologically in basal conditions, after isoproterenol infusion (2–4 μ/min) and during submaximal bicycle exercise test, at a constant workload equal to that which increases the sinus rate to the same extent (140 beats/min) induced by isoproterenol infusion. Accessory pathway ERP was evaluated at the same driven rate (150 beats/min) in both instances. In the control study as during both tests atrial fibrillation paroxysms were induced by burst stimulation. In control conditions the rate increase from 100 to 150 beats/min induced a reduction of accessory pathway ERP from 266 ± 27 msec to 244 ± 22 msec (P < 0.005). At the same driven rate of 150 beats/min, isoproterenol infusion and exercise test induced a more marked shortening of accessory pathway ERP to 211 ± 28 msec (P < 0.005) and to 214 ± 29 msec (P < 0.005), respectively. Atrial fibrillation paroxysms lasting more than 10 seconds were induced in 20/20 cases in the control study, in 15/20 during isoproterenol infusion and in 13/19 cases during exercise test. The shortest cycle length during atrial fibrillation was reduced from a basal value of 253 ± 72 msec to 204 ± 27 msec (P < 0.05) during isoproterenol infusion and to 236 ± 32 msec (NS) during exercise test. Similar behavior was observed in the mean cycle length during atrial fibrillation (from 372 ± 67 to 291 ± 36 and to 329 ± 70 msec, respectively). In conclusion, isoproterenol and exercise test, when exerting the same effect on sinus rate, induce the same accessory pathway ERP decrease, mainly due to a direct electrophysiological effect, which overcomes that secondary to increase in heart rate. Isoproterenol reduces the shortest and mean RR intervals during atrial fibrillation more than exercise test, probably because other determinants in addition to the accessory pathway ERP may influence heart rate during atrial fibrillation. The increase of sympathetic tone seems to reduce atrial fibrillation electrical inducibility.
The Range of Sensors and Algorithms Used in Rate Adaptive Cardiac Pacing
Authors: LAU CHU‐PAK
Published: July 2006

Implantable sensors play an important role in physiological cardiac pacing. Sensors can be classified according to the technical methods in which sensing is achieved: the sensing of the evoked ventricular response, intrathoracic impedance and body acceleration forces, and the incorporation of special sensors on pacing electrodes. These sensors differ in their relative merits in terms of speed, proportionality, sensitivity, and specificity of rate response. The efficacy of a sensor can be significantly modified by the algorithm used in relating sensor signal to a pacing rate change. The currently available types of sensors and algorithms are summarized and compared in this review article. The relative merits of these sensors and algorithms form the basis for designing a multisensor pacing system.
A Case of Cardiac Foreign Bodies Associated with Four Types of Tachycardias
Authors: KURUMA AKINORI , SAITOH HIROKAZU , INO TAKESHI , ATARASHI HIROTSUGU , KATOH TAKAO , HAYAKAWA HIROKAZU , IKESHITA MASATOSHI , TANAKA SHIGEO
Published: July 2006

A case of cardiac foreign bodies leading to development of four varieties of automatic tachycardia is reported. A 51‐year‐old male with aortic regurgitation was admitted to our hospital because of palpitations. An electrocardiogram revealed junctional tachycardia with or without left bundle branch block, and two types of fascicular tachycardias. Computed tomography showed metallic foreign bodies from a fractured guidewire in the membranous portion of the interventricular septum, which was inadvertently retained when he underwent diagnostic cardiac catheterization at the age of 27.
A Technique Utilizing a Steerable Hydrophilic Guidewire for Permanent Pacemaker Implantation
Authors: STAMATO NICHOLAS J. , O'TOOLE MICHAEL F. , VALGUISTI ED , ENGER ELAINE L.
Published: July 2006

We report the use of a steerable hydrophilic guidewire for permanent pacemaker implantation. This wire, previously used for peripheral vascular and cardiac angiography, is able to be steered and passed in many situations when a standard guidewire cannot be used. We report three cases where the standard F‐tipped guidewire could not be passed fay either the cephalic or subclavian route and the hydrophilic guidewire allowed for successful atraumatic placement of a sheath and pacemaker lead.
Failure of Defibrillator Paddle as Mimic for Subcutaneous Patch Lead During Nonthoracotomy Implantable Cardioverter Defibrillator Lead Configuration Assessment
Authors: PACHULSKI ROMAN T. , KLEIMAN ROBERT B. , JOSEPHSON MARK E. , MARCHLINSKI FRANCIS E.
Published: July 2006

It is a common, although virtually unsubstantiated, practice to assess the efficacy of nonthoracotomy lead systems for implantable Cardioverter defibrillators using a defibrillator paddle as mimic for the subcutaneous patch lead. We report a case in which an adequate defibrillation threshold was documented with the nonthoracotomy lead system using a defibrillator paddle but not following implantation of the true subcutaneous patch lead. This case suggests that the substitution of a defibrillator paddle for the subcutaneous patch lead during nonthoracotomy lead system evaluation may have significant limitations in assessing lead configuration efficacy.
Programmable External Automatic Antitachycardia Pacing as a Bridge to Definitive Therapy in Patients with Recurrent Sustained Ventricular Tachycardia
Authors: AHERN THOMAS S. , NYDEGGER CHARLES , GREENSPON ARNOLD J. , KIDWELL GREGORY A. , HESSEN SCOTT E. , MCCORMICK DANIEL J. , KUTALEK STEVEN P.
Published: July 2006

The efficacy and safety of external programmable automatic antitachycardia pacemakers (ATPs) used in the critical care setting for recurrent sustained monomorphic ventricular tachycardia (VT) was evaluated. Ten patients who had failed a mean of 4.0 ± 1.4 antiarrhythmic medications (range 2–7) and who had previously required electrical cardioversion for VT were enrolled. Prior to ATP use, successful overdrive pacing termination of VT was demonstrated in all patients. IntertachTM (lntermedics, Inc.; n = 9) and OrthocorR II (Cordis, Inc.; n = 1) ATPs were attached to temporary bipolar transvenous or epicardial pacing leads. Mean patient age was 66.4 ± 11.5 years, and mean left ventricular ejection fraction was 22 ± 7.5%. At the time of initial ATP use, mean VT cycle length was 347 ± 88 msec (range 280‐550 msec). A burst scanning antitachycardia pacing algorithm was used in each patient; one patient was also treated with a fixed rate burst adapted to VT cycle length. The duration of ATP use ranged from 2–25 days (median 5), successfully terminating < 3,369 VT episodes (median 3, range 0 to < 3,103 episodes per patient). Two episodes of ATP induced rate acceleration occurred, each successfully terminated by the ATP. Only two patients required external cardioversion during ATP use, one for primary ventricular fibrillation and one for rapid polymorphic VT associated with antiarrhythmic drug withdrawal. ATPs also provided antibradycardia pacing and allowed for serial programmed ventricular stimulation. No complications were associated with transvenous catheter or ATP use. Temporary use of external ATPs acted as a bridge to definitive antiarrhythmic measures: endocardial resection (n = 2), defibrillator implant (n = 2), chronic amiodar‐one therapy (n = 4), electrophysiologically guided antiarrhythmic therapy (n = 1), and cardiac transplantation (n = 1). Thus, temporary automatic antitachycardia pacing provides a safe, rapid, and effective means of VT termination in a critical care setting, with a low frequency of tachyarrhyfhmia rate acceleration, enabling its use as a bridge to definitive treatment for sustained VT.
Radiofrequency Ablation of Bilateral Quadruple Accessory Pathways in a Patient with Wolff‐Parkinson‐White Syndrome
Authors: CHEN SHIH‐ANN , CHIANG CHERN‐EN , CHIOU CHUEN‐WANG , WANG SHIH‐PU , CHIANG BENJAMIN N. , CHANG MAU‐SONG
Published: July 2006

A patient with drug refractory supraventricular tachycardia showed electrophysiological evidence of bilateral quadruple accessory pathways. The conduction was bidirectional in the left posteroseptal and left posterolateral accessory pathways, antegrade in the right lateral accessory pathway, and retrograde in the right anterior accessory pathway. The four pathways participated in seven types of reciprocating tachycardias. Radiofrequency ablation eliminated the four pathways successfully. The patient was asymptomatic and free of any drug during a 10‐month follow‐up.
Comparison of Clinical Benefits and Outcome in Patients with Programmable and Nonprogrammable Implantable Cardioverter Defibrillators
Authors: MEHTA DAVENDRA , SAKSENA SANJEEV , KROL RYSZARD B. , MAKHIJA VINOD
Published: July 2006

Technological advances in implantable cardioverter defibrillators (ICDs) have provided a variety of programmable parameters and antitachycardia therapies whose utility and impact on clinical outcome is presently unknown. ICDs have capabilities for cardioversion defibrillation alone (first generation ICDs), or in conjunction with demand ventricular pacing (second generation ICDs), or with demand pacing and antitachycardia pacing (third generation ICDs). We examined the pattern of antitachycardia therapy use and long‐term survival in 110 patients with sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). Group I included 62 patients with nonprogrammable first generation ICDs that delivered committed shock therapy after ventricular tachyarrhythmia detection based on electrogram rate and/or morphology was satisfied. Group II included 48 patients with multiprogrammable ICDs (including second and third generation ICDs) that had programmable tachyarrhythmia detection based on rate and tachycardia confirmation prior to delivery of electrical treatment with either programmable shocks and/or, as in the third generation ICDs, antitachycardia pacing. Incidence and patterns of antitachycardia therapy use and long‐term survival were compared in the two groups. The incidence of appropriate shocks in patients who completed 1 year of follow‐up was significantly greater in group I (30 of 43 patients = 70% vs 11 of 26 patients = 42%; P < 0.05). In the total follow‐up period, a significantly larger proportion of group I patients as compared to group II patients used the shock therapies (46 of 62 patients = 74% vs 25 of 48 patients = 52%; P < 0.01), with the majority doing so within the first year of implantation (96% and 92%, respectively). Although the frequency of antitachycardia therapy activation was similar, the number of shocks delivered per patient was lower in group II, particularly in the initial 3 months of follow‐up (P = 0.06). No clinical variable aided in identifying users from nonusers of antitachycardia therapy. Arrhythmic mortality was virtually eliminated in both groups. Two‐year actuarial cardiac survival in the two groups was similar (group I = 78% vs group II = 84%; P < 0.2J. Survival from cardiac mortality in users and nonusers of antitachycardia therapies was also similar in both groups (P < 0.2) and in the total patient group (P < 0.2). We conclude that programmable ICDs continue to confer advantages in prevention of sudden death that were observed with nonprogrammable ICDs and can be expected to improve patient tolerance and physician acceptance of device therapy for VT/VF.
Histologic Findings of the Heart and the Conduction System in the First Patient Who Underwent Catheter Ablation
Authors: BHARATI SAROJA , SCHEINMAN MELVIN , LEV MAURICE
Published: July 2006

This is a detailed pathological examination of the heart including the conduction system (CS) from a 64‐year‐old male who had catheter ablation of the atrioventricular (AV) junction for intractable atrial fibrillation. This is the world's first human who had this procedure, and who survived 3 years and 8 months, and later died of congestive heart failure. Pathologically, the heart was hypertrophied and enlarged. Historically, there were chronic inflammatory cells, marked fatty metamorphosis with fibrosis of the atria, the approaches to the AV node, and the AV node, with almost isolation of the node from the atria, and considerable fibrosis of the bundle and bundle branches. In addition, there was fibrosis of the summit of the ventricular septum with chronic inflammatory cells. These represent the sequelae of the ablation procedures. It is not known how much of the pathological findings contributed to the cardiac hypertrophy and impairment of cardiac function,
Distinct Activation Patterns of Idioventricular Rhythms and Sympathetically‐Induced Ventricular Tachycardias in Dogs with Atrioventricular Block
Authors: CARDINAL RENÉ , SCHERLAG BENJAMIN J. , VERMEULEN MICHEL , ARMOUR J. ANDREW
Published: July 2006

To investigate mechanisms of ventricular impulse formation in response to sympathetic stimulation in the healthy canine heart in situ, we compared the patterns of ventricular activation during the idioventricular rhythms arising after complete atrioventricular (AV) block and ventricular tachycardias induced by RSG or LSG stimulation. Isochronal maps were generated by computer from 116‐127 unipolar electrograms recorded from the entire ventricular epicardium in 15 open chest, anesthetized dogs. In eight of these, bipolar electrograms were recorded with plunge electrodes from 11 selected endocardial sites located below epicardial breakthrough areas. Intracardiac recordings from the His‐Purkinje system were made with electrode catheters. After electrograms were recorded during sinus rhythm, complete AV block was induced by injecting formaldehyde into the AV node and idioventricular rhythms occurred spontaneously at a rate of 37 ± 12 beats/min (mean ± SD, n = 25). During idioventricular rhythms, endocardial activation preceded the earliest epicardial breakthrough, which occurred in either the right anterior paraseptal region, antero‐apical left ventricle, or posteroapical left ventricle. These sites were consistent with a focal origin in the subendocardial His‐Purkinje system. Total epicardial activation times lasted for 47 ± 13 msec (n = 40). Idioventricular rhythms were suppressed by overdrive pacing (intermittent trains of ten beats with decremental cycle length from 500 to 200 msec) or by intravenous calcium infusion (to plasma levels of 10.1‐15.2 mM). Right or left stellate ganglion stimulation increased idioventricular rhythm rates fto 52 ± 13 beats/min, n = 28) and also induced, in all preparations, ventricular tachycardias that had significantly faster rates (189 ± 55 beats/min, n = 27, P < 0.005), Ventricularfibrillafion was induced after brief runs of ventricular tachycardia in five of the preparations. During ventricular tachycardias, epicardial activation occurred on the right ventricular outflow tract or the posteroiateral wall of the left ventricle, and preceded endocardial activation in 50% of cases. Total epicardial activation times (103 ± 29 beats/ min) were significantly longer than during idiovenfricular rhythms (P < 0.005). Ventricular tachycardias displayed overdrive excitation at critical pacing cycle lengths (360–280 msec) and were not suppressed by calcium infusion. Thus, differential mechanisms of impulse formation with distinct localizations can be elicited from healthy ventricular myocardium.
Feasibility of an Implantable Arrhythmia Monitor
Authors: LEITCH JAMES , KLEIN GEORGE , YEE RAYMOND , LEE BRIAN , KALLOK MICHAEL , COMBS WILLIAM , ERICKSON MARK , BENNETT TOM
Published: July 2006

Conventional Holter monitoring is of limited benefit in patients with infrequent symptoms suspected to be related to arrhythmia. A small recorder implanted subcutaneously might obviate many limitations of conventional monitoring. To determine the feasibility of obtaining adequate electrocardiographic signals from such a device, a prototype was temporarily implanted in 17 patients undergoing pacemaker implantation. The prototype contained four disc‐shaped titanium electrodes, 0.21 inches in diameter embedded in epoxy. The four electrodes were in a square configuration spaced 0.72 inches center to center and were placed face down in a subcutaneous pocket in the left pectoral region. Bipolar recordings were made from a horizontal pair, a vertical pair, and both diagonal pairs of electrodes (interelectrode distance 1.02 inches) and recorded on electromagnetic tape after filtering at 0.5‐250 Hz. The mean peak‐to‐peak amplitude in each configuration was determined over a five‐beat interval. Clear recordings were obtained from all 17 patients with recognizable P, QRS, and T waves. The amplitude of the signals obtained from the diagonal pairs of electrodes (175 ± 51 and 170 ± 54 μV) were greater than obtained from either the vertical pair (142 ± 62 μV, P = 0.08 compared to diagonal electrodes] or the horizontal pair of electrodes (105 ± 54 μV, P < 0.01). The maximum amplitude recorded from any configuration was 189 ± 54 μV. In six patients the device was also tested with the electrodes face up in the subcutaneous pocket. In this position, there was a slight decrease in signal amplitude (maximum amplitude electrodes face up 136 ± 49 μV compared to 144 ± 49 μV face down, P = NS), but baseline stability was greatly improved during pectoral muscle contraction. These results demonstrate that a device with an interelectrode distance of 1 inch is able to record adequate electrocardiographic signals when placed subcutaneousiy in the left pectoral region. A fully implantable device of similar size, with continuous loop memory and telemetry, might be useful in patients with recurrent unexplained syncope.
Physiology of “Atypical” Atrioventricular Junctional Reentrant Tachycardia Occurring Following Radiofrequency Catheter Modification of the Atrioventricular Node
Authors: GOLDBERGER JEFFREY , BROOKS RODNEY , KADISH ALAN
Published: July 2006

The physiology of atypical atrioventricular junctional reentrant (achycardia (AVJRT) occurring following catheter modification of the AV node is poorly defined. Six patients undergoing radiofrequency current catheter modification of the AV node had inducible atypical AVJRT before or after AV nodal modification. Typical AVJRT was differentiated from atypical AVJRT by a ventriculoatrial (VA) time < 60 msec in the His‐bundle electrogram recording. Five of six patients had typical AVJRT and two had atypical AVJRT prior to AV nodal modification. Following anterior approach AV nodal modification, previously undetected atypical AVJRT was induced in four patients. Earliest retrograde atrial activation in the posterior septum was documented in all patients with atypical AVJRT prior to modification and in three four patients with atypical AVJRT following modification. The AH intervals during tachycardia were 320 ± 52 msec in typical AVJRT, 88 ± 33 msec in the premodification atypical AVJRTs, and 172 ± 12 msec in the postmodification atypical AVJRTs (P − 0.0001). The AHJRA ratios were 4.1 ± 0.9 in typical AVJRT, 0.5 ± 0.2 in the premodification atypical AVJRTs, and 0.9 ± 0.2 in the postmodification atypical AVJRTs (P = 0.0001). Two patients with postmodificafion atypical AVJRT underwent further posterior approach AV node modification that resulted in VA block. One patient with postmodification atypical AVJRT had further anterior approach AV nodal modification that resulted in heart block. The retrograde limb of the atypical AVJRT seen following anterior approach AV nodal modification is a posterior, slow pathway.
Detecting Right Ventricular Volume Changes Using the Conductance Catheter
Authors: WOODARD JOHN C. , BERTRAM CHRISTOPHER D. , GOW BARRY S.
Published: July 2006

The purpose of this study was to assess the role of conductance catheter position within the right ventricle in obtaining adequate indications of phasic changes in ventricular volume. Possible applications of this lechnology are in rate responsive pacemakers and implantable defibrillators. The conductance catheter was placed in the right ventricle by cannulation of a jugular or femoral vein or a branch of the pulmonary artery. Position within the ventride was documented from biplane fluoroscopy. Stroke volume was perturbed by: bolus injection of blood, vagal stimulation, venous infusion of methylcholine chloride, or isoprenaline. Four criteria were used to assess the quality of volume signals: (1) volume signal phase relative to the electrocardiogram; (2) magnitude parity of volume change from each electrode pair; (3) freedom from artifact; and (4) indication of stroke volume change during interventions. Greyhound dogs of either sex (n = 33), weight 20–32 kg. A total of 236 recordings from 14 distinct catheter positions were analyzed. Catheter positions originating from a femoral cannulation and one position from the pulmonary artery gave markedly superior volume transduction compared to those from the jugular route. Although right ventricular volume transduction was possible from all catheter trajectories, those resulting from the femoral approach were clearly superior. In the right ventricle, the inability to transduce a sufficient proportion of ventricular volume, in concert with the potential sensitivity of the catheter to atrial volume changes, may seriously limit the potential of the conductance technique in the applications envisaged.
Observations on the Epicardial Activation of the Normal Human Heart
Authors: PIEPER CARL F. , PACIFICO ANTONIO
Published: July 2006

Serial hand mapping techniques in man have identified 3 to 5 sites of epicardial breakthrough (EBT). However, transmural epicardial excitation from the widely distributed His/Purkinje system suggests a more complicated pattern may exist. Multielectrode arrays used with large mapping systems during surgery often present complicated and sometimes inconsistent activation patterns. The purpose of this work is to reconcile epicardial activation in the normal human heart with anatomical and endocardial/intramural physiological recordings using multichannel computer mapping requiring only a single beat, and rigorously defined and applied activation time detection algorithms. Eighteen subjects undergoing surgery for Wolff‐Parkinson‐White syndrome were recorded with a 119 site sock array during nonpreexcited sinus rhythm. None had evidence of coronary artery disease and all exhibited a normal 12‐lead ECG except during periods of preexcitation or tachycardia. Each was recorded bipolarly and four also were recorded monopolarly. Recordings revealed 8.0 ± 1.6 EBTs (range 5 to 12). Closely spaced, multiple EBTs often were observed and usually confirmed using different activation time detection algorithms. The earliest EBT always occurred over the anterior right ventricle at 14.3 ± 6.5 msec (range ‐ 1 to 29 msec) after QRS onset. Subsequent EBTs could occur at any ventricular site with variable latencies. In contrast to previous reports describing epicardial spread of activation from a few foci, a mosaic of epicardial activation emerges. These data are consistent with endocardially initiated transmural activation of the epicardium suggested by the anatomy of the His/Purkinje system and intramural recordings.
Atrial Flutter—Update on the Mechanism and Treatment
Authors: OLSHANSKY BRIAN , WILBER DAVID J. , HARIMAN ROBERT J.
Published: July 2006

Atrial flutter is a common and usually benign but symptomatic supraventricular tachycardia. There is a striking similarity between patients with atrial flutter suggesting a common substrate despite the presence or absence of underlying heart disease. In man, the mechanism is a single reentrant circuit originating in the right atrium whose center appears to be functional within the anatomical constraints of the right atrium. The reentrant circuit of atrial flutter contains an area of slow conduction in the inferior right atrium but the size and exact location is uncertain. Drug therapy directed at terminating and preventing atrial flutter has been available for many years. The efficacy and safety of this therapy is not as well tested as is the same therapy for atrial fibrillation. The most effective way to terminate atrial flutter is a nonpharmacological approach. Several nonpharmacological methods provide new treatment options in the management of patients with drug resistant or hemodynamically unstable atrial flutter. The use of anticoagularion for this disorder is still evolving. There is a risk of clinically apparent thromboemboli in some patients with atrial flutter although the risk appears less than that for utrial fibrillation. In the future, refinements and improvements in therapy for atrial flutter will likely be derived from a better understanding of its mechanism.
Postpausal Ventricular Fibrillation Analyzed by Holter‐ECG: A Case Report
Authors: NILSSON G. , WIBERG S. , BAND S. , JONASSON T.
Published: July 2006

A 70‐year‐old male patient with a myocardial infarction, 3 months previously, happened to be wearing a Holter monitor at cardiac arrest during micturition. The patient had ventricular fibrillation (VF) and was succesfully resuscitated by means of defibrillation. Analysis of the Holter tape revealed utrial fibrillation and secondary ventricular premature beats (VPB), i.e., VPBs dependent upon a relatively long interval between the two preceding heartbeats. The VF was preceded by an especially long R‐R interval (1.45 sec) following a run of especially short R‐R intervals implying the sharpest decelerution of the ventricular rate during 1 hour Holter recording preceding the cardiac arrest. A peculiar large alteration of the T wave configuration was also found to precede the VF.
Three‐Dimensional Electrogram Mapping Improves Ablation of Left‐Sided Accessory Pathways
Authors: FISHER WESTBY G. , SWARTZ JOHN F.
Published: July 2006

Conventional electrogram mapping techniques for localization of accessory pathways during radiofrequency ablation procedures are time consuming and often inaccurate. We hypothesized that a computer generated, three‐dimensional electrogram of retrograde atrial activation created from signal‐averaged sequential endocardial bipolar electrograms (collected from the atrial aspect of the mitral annulus using a single transseptal catheter and then time aligned to a known myocardial activation reference) would improve left‐sided accessory pathway afrial insertion site identification and increase ablation efficiency. Ablation efficiency was defined by procedure time, fluoroscopy time, duration of radiofrequency energy required to achieve initial accessory pathway block, cumulative ablation energy per procedure, and number of radiofrequency energy applications. Patients with single left‐sided accessory atrioventricular connections were studied. Standard mapping results in 31 patients (group A) were compared to a three‐dimensional electrogram approach used in 26 patients (group B). Three‐dimensional electrogram mapping reduced procedure time (group A 3.8 ± 1,6 vs group B 2.8 ± 0.9 hours, P < 0.004), fluoroscopy time (group A 45,3 ± 35.0 vs group B 25.1 ± 10,5 min, P < 0.02), time to accessory pathway block (group A 2.6 ± 1.5 vs group B 1,2 ± 0.5 sec, P < 0.002), cumulative radiofrequency energy (group A 2126 ± 2207 vs group B 636 ± 586 joules, P < 0.0008), and radiofrequency energy applications (group A 5.0 ± 4.4 vs group B 1.7 ± 1.2, P < 0.0002). We conclude that three‐dimensional electrogram mapping improves left‐sided accessory pathway atrial insertion localization, reduces ablation procedure time and radiation exposure, and improves ablation efficiency.
Proarrhythmic Effects of Reactive Hypoglycemia
Authors: ROKAS STELIOS , MAVRIKAKIS MYRON , ILIOPOULOU ANGELIKI , MOULOPOULOS SPYRIDON
Published: July 2006

A patient with refractory atrioventric‐ular nodal reentry tachycardia is reported in whom it was possible to document that reactive hypoglyce‐mia was the trigger for aggravation of arrhythmia. Over a period of 6 years, a series of electrophysiological studies revealed that, when the patient was in a hypoglycemic state, initiation of tachycardia was easy and most importantly that tachycardia termination by extra‐stimulus pacing always failed. Furthermore, atrial fibrillation was inducible or spontaneously occurred only when the blood glucose level was reduced by IV insulin administration.
Inverted Pacemaker Mediated Tachycardia Induced During Noninvasive Electrophysiology Testing
Authors: BERNS ELLISON , KEEFE JAMES M.
Published: July 2006

This report describes a case in which an implanted pacemaker programmed to perform noninvasive electrophysiology testing resulted in an unusual form of pacemaker mediated tachycardia. The method of chest wall stimulation was used by programming a unipolar, triggered pacing mode with a short refractory period. In the AAT mode, far‐field R wave sensing occurred beyond the physiological atrial refractory period. The triggered atrial response resulted in a single chamber, pacemaker mediated tachycardia.
Propafenone Associated Agranulocytosis
Authors: MIWA LINDA J. , JOLSON HEIDI M.
Published: July 2006

Propafenone hydrochloride was approved for marketing by the United States (U.S.) Food and Drug Administration (FDA) in November 1989. During U.S. clinical trials of propafenone, one case of agranulocytosis was seen. Seven additional cases have been reported outside the U.S. One German report of profound but reversible granulocytopenia appeared in 1982. In January 1991, the FDA reviewed adverse events reported with propafenone. Four reports of agranulocytosis were identified and are described. The reporting rate of approximately one case of agranulocytosis per 10,000 propafenone prescriptions per year likely underestimates the true incidence of this adverse event.
Atrial Natriuretic Factor Release During Exercise in Patients Successively Paced in DDD and Rate Matched Ventricular Pacing
Authors: BLANC JEAN‐JACQUES , MANSOURATI JACQUES , HITTER PHILIPPE , NITZSCHE RÉMY , PAGES YVES , GENET LOIC , MORIN JEAN‐FRANÇOIS
Published: July 2006

Dual chamber pacemakers were implanted in nine patients with permanent second or third degree AV block feight had complete retrograde block). Two identical exercise tests were performed after at least 1 month after implantation. During the first test (T1) the pacemaker was programmed to the DDD mode and heart rates were recorded every 15 to 30 seconds during exercise and 30 minutes after exercise. Following 30 minutes of rest, the implanted pacemaker was programmed to the VVT mode and driven by an external pacemaker via a skin electrode. The second exercise test (T2) was then performed and the rate of the external pacemaker was progressively changed to reproduce exactly the rate observed during T1 at the same exercise stress. Atrial natriuretic factor (ANF) levels were determined at rest, at regular intervals during exercise, and 30 minutes after exercise. ANF levels and release were statistically higher during rate matched ventricular, than DDD pacing. It is concluded that preservation of AV synchrony reduces ANF release induced by heart rate acceleration during exercise.
Catheter Ablation of Ventricular Tachycardia: Role of the Underlying Etiology and the Site of Energy Delivery
Authors: TRAPPE HANS‐JOACHIM , KLEIN HELMUT , AURICCHIO ANGELO , WENZLAFF PAUL , LICHTLEN PAUL R.
Published: July 2006

The role of DC catheter ablation (CA) to treat patients with sustained monomorphic ventricular tachycardia (VT) is still debated. To assess the efficacy of VT CA, we studied the follow‐up of 49 patients with VT who underwent CA. There were 33 patients with an old myocardial infarction [MI] (group G I) and 16 patients had noncoronary VT (group G II): CA was performed at the earliest endocardial activation (EEA)(20 patients in G I, 14 patients in G II) or at the area of slow conduction (ASC) (13 patients in GI, 2 patients in GII). During the mean follow‐up of 35 ± 25 (1–79) months, there were 17 patients in G I (52%) and 12 patients in G II (75%) with VT recurrences (P < 0.05). Recurrences of VT was observed in 4 of 15 patients (27%) when CA was performed at the ASC, compared to 25 of 34 patients (74%) with CA at the EEA (P < 0.01). These data show that DC CA is more successful in patients with coronary artery disease, particularly when CA is performed at the ASC.
Is DDD Pacing Superior to VVI,R? A Study on Cardiac Sympathetic Nerve Activity and Myocardial Oxygen Consumption at Rest and During Exercise
Authors: LINDE‐EDELSTAM CECILIA , HJEMDAHL PAUL , PEHRSSON S. KENNETH , ÅSTRÖM HANS , NORDLANDER ROLF
Published: July 2006

Rate responsive ventricular pacing (VVI,R) has been demonstrated to equal atrial synchronous ventricular pacing (DDD) with regard to hemodynamics and exercise tolerance. Whether the two modes are also comparable, with regard to cardiac metabolic effects, is not yet dear. We assessed central hemodynamics, cardiac sympathetic nerve activity fcardiac norepinephrine overflow), and myocardial oxygen consumption in 16 patients treated with rate responsive atrial synchronous ventricular pacemakers (DDD,R), due to high degree AV block. The study was performed at rest and during supine exercise at two workloads (30 ± 12 and 68 ± 24 watts, respectively) during VDD and rate matched VVI pacing (VVIm). Ventricular rates at rest and during both workloads were almost identical. Cardiac output at rest tended to be higher in the VDD mode, due to a slightly higher stroke volume. Central pressures including right atrial pressure and pulmonary capillary wedge pressure were similar in the pacing modes. The coronary sinus blood flow, the coronary sinus arteriovenous oxygen difference, and the myocardial oxygen consumption did not differ between the two pacing modes. Cardiac norepinephrine overflow was similar in the two pacing modes, at rest or during exercise. Thus, we found no significant differences between VDD and VVIm pacing with regard to central hemodynamics, cardiac sympathetic nerve activity (cardiac norepinephrine overflow), or myocardial oxygen consumption either at rest or during moderate exercise.
Prospective Evaluation of Heart Block Complicating Early Lyme Disease
Authors: RUBIN DAVID A. , SORBERA CARMINE , NIKITIN PATRICIA , MCALLISTER ANNEMARIE , WORMSER GARY P. , NADELMAN ROBERT B.
Published: July 2006

Lyme disease is a recognized cause of heart block/carditis. The incidence of heart block complicating early Lyme disease has not been prospectively evaluated. In this study, 61 patients with early Lyme disease documented by the rash of erythema migrans were prospectively evaluated for carditis. Fifty five of 61 patients had a repeat examination 3 to 4 weeks after initiation of antibiotic therapy. Only one of 61 patients (1.6%) presented with heart block, which resolved with antibiotics. None of the 54 patients without heart block on initial presentation had a change in any measured electrocardiographic parameter or progressed to heart block after antibiotics. Therefore, early Lyme disease appears to be infrequently complicated by heart block. Early administration of antibiotics may prevent the development of heart block fcarditis.
Safe Introducer Technique for Pacemaker Lead Implantation
Authors: BYRD CHARLES L.
Published: July 2006

Over the last several years, an introducer approach for pacemaker lead insertion has evolved that eliminates most introducer‐related complications. The approach consists of defining a safe region for intra thoracic cannulatiort of the subclavian vein. If specific conditions cannot be met for entering the “safe” region or if the vein cannot be found, the subclavian vein is cannulated extrathoracically. Recently, this technique was used in 263 consecutive patients undergoing pacemaker implantation. The infrathoracic portion of the subclavian vein was used in 239 (90.9%) cases and the extrathoracic portion in 24 (9,1%). One hundred and ninety‐eight (75.3%) cases were right‐sided and 65 (24.7%) were left‐sided. On the right side, 177 (89.4%) used the intrathoracic portion of the subclavian vein and 21 (10.6%) used the extrafhoracic portion. On the left side, 62 (95.4%) used the intrathoracic portion and three (4.6%) used the extrathoracic. The introducer technique was successful in all cases and there were no introducer‐related complications.