bluuebunny/crossref_metadata_2025 huggingface dataset:
Maintenance of Atrioventricular Sequence After His‐Bundle Ablation for Paroxysmal Supraventricular Rhythm Disorders: A Unique Use of the Fallback Mode in Dual Chamber Pacemakers
Authors: VAN WYHE GALEN , SRA JASBIR , ROVANG KAREN , GILBERT CAROL , AKHTAR MASOOD , TCHOU PATRICK
Published: July 2006

The usual mode of controlling ventricular rate after His‐bundle ablation is placement of a ventricular demand rate responsive pacemaker. Atrioventricular synchrony is therefore lost in individuals whose atrial rhythm disturbances are paroxysmal. Thirty‐seven His ablations were performed at this institution, since January of 1983, for atrial rhythm disturbances that were not suppressible with medical therapy alone. Of those, ten patients were identified whose atrial rhythm disturbances were intermittent and who would otherwise benefit by having proper atrioventricular sequence during sinus rhythm. These patients underwent placement of a dual chamber pacemaker system having a fallback mode. At a mean follow‐up period of 17 ± 11 months, eight patients continued to maintain proper atrioventricular sequence with ventricular pacing tracking atrial activation during sinus rhythm. Supraventricular tachyarrhythmic attacks were associated with attainment of the programmed upper rate limit at which time the fallback mode was activated and the pacemaker automatically converted to a ventricular demand (VVJ) mode. Restoration of normal sinus rhythm was associated with restoration of proper afrioventricular sequence. Two patients have developed chronic atrial fibrillation and their pacemakers continue to function in the fallback mode as VVI devices. In conclusion, intermittent supraventricular tachyarrhythmias which are resistant to drug therapy can be treated with His ablation and dual chamber pacing utilizing special pacemaker features such as the fallback mode.
Spontaneous Occurrence of the Induced Cardioinhibitory Vasovagal Reflex
Authors: ODDONE DANIELE , BRIGNOLE MICHELE , MENOZZI CARLO , GIANFRANCHI LORELLA , LOLLI GINO
Published: July 2006

ECG recording of spontaneous, neurally‐mediated syncope is rare. We have observed ten patients who sustained 70 syncopal episodes in whom: (1) EGG monitoring recorded syncope caused by ventricular asystole (AV block, three patients; sinus arrest; seven patients); (2) syncope and the spontaneously observed arrhythmias were reproducible by carotid sinus massage, upright tiit test, or eyebaU pressure; and (3) no discernable cause or precipiting factors were defected. Two patients had a history of cardiac disease and four patients had only mild nonclinical EGG or echocardiographic abnormalities. Syncopai episodes recorded during Holter monitoring were of sudden onset in four patients and preceded by prodromal symptoms in six patients. The maximum RR pause was 9.4 ± 3.7 seconds (range 4.5—15). Electrophysiological evaluation was normal in seven patients. Slight sinus node dysfunction or atrio‐ventricular conduction abnormalities were noted in three others. The clinical characteristics of spontaneous and induced episodes strongly suggest that increased vagal tone played a role in causing the spontaneous events. Vagal stimulation tests are useful for the diagnosis of syncope of unknown origin.
Observations on the Initiation of Sustained Ventricular Tachycardia by Programmed Stimulation
Authors: MOROE KAZUO , COELHO ALDO , CHUN YEONG‐HWA , GOSSELIN ARTHUR J.
Published: July 2006

We analyzed the initiation of sustained monomorphic ventricular tachycardia (VT) by programmed ventricular stimulation (PVS) in 50 consecutive patients who had clinical VT or aborted sudden cardiac death with remote myocardial infarction. In 25 of 50 patients, the first induced QRS complex of VT was morphologically identical to the succeeding QRS complexes of VT (type I). In 25 other patients, the first VT beat had a different morphology (type II). Type I had a significantly longer VT cycle length than type II (333 ± 65 msec and 293 ± 66 msec, P = 0.036). Type II VT initiation required more aggressive stimulation protocol than type I (type I: type II; number of extrastimulus required for induction 2.5 ± 0.9 : 3.0 ± 0.6, P = 0.026; shortest extrastimuli coupling interval 244 ± 28 msec : 220 ± 23 msec, P = 0.002). The interval between the last extrastimulus and the onset of the first VT beat was 408 ± 88 msec in type I and 336 ± 75 msec in type II (P= 0.004). Furthermore, there was good correlation between the VT cycle length and the interval from last extrastimulus to the onset of nonpaced beat in type I but not in type II. We conclude; (1) in type I VT initiation, when compared to type II, the induced sustained VT had slower rates and required less extrastimuli and longer coupling interval of extraslimulus for induction; (2) in type I, initiation of VT suggests establishment of a reentrant circuit with the first nonpaced beat; (3) in type I, shortening of refractoriness is more important than the conduction delay in establishing sustained VT; and (4) in type II, the mechanisms of initiation of VT are heterogeneous.
The Construction of Endocardial Balloon Arrays for Cardiac Mapping
Authors: CHEN THOMAS C.K. , PARSON IAN D. , DOWNAR EUGENE
Published: July 2006

The advent of multichannel recording systems has enabled chinical mapping to be performed on a beat‐by‐beat basis using multi‐electrode arrays. Surgical ablation of ventricular arrhythmias generally requires endocardial mapping, Clinical usage has indicated that an inflatable balloon array is the most practical design and can obviate the need for ventriculotomy by a transatrial introduction in the deflated state. Successful experience with the left ventricular balloon led to the development of a right ventricular balloon array suitably configured to extend into the outflow tract. Custom moulds are used to create an appropriate balloon from liquid latex. Nylon cloth is cut from a cardboard pattern to fashion a stretchable sock to envelope the balloon. Electrodes are formed by stitching 2‐mm silver beads to the balloon sock in a preconfigured pattern. Teflon‐coated 31 G multi‐strand stainless‐steel wires 130 mm in length connect the electrode beads by solder to the multipin connectors for easy hookup to the amplifier inputs. Tygon tubing 0.53 cm in diameter fitted to the balloon allows inflation and pressure monitoring. This basic design has been successfully implemented for the last 6 years.
Incessant Ectopic Atrial Tachycardia and Sudden Death
Authors: SOSA EDUARDO , MARCIAL MIGUEL BARBERO , SCANAVACCA MAURICIO , BELLOTTI GIOVANNI , PILEGGI FULVIO
Published: July 2006

A patient with refractory and incessant ectopic atrial tachycardia (IEAT) is reported in whom it was possible to document, during EGG (Holter) the occurrence of aborted sudden death by spontaneous ventricular fibrillation (VF). Following the second of two attempts at surgical ablation of the origin of the IEAT, the patient has been asymptomatic without antiarrhythmic drugs and in sustained sinus rhythm for 24 months. Although we cannot exclude the residual action of amiodarone and flecainide (proarrhythmia) or the residual peripartum cardiomyopathy it is probable that the observed VF was a true complication of a cardiomyopathy induced by a chronically increased heart rate (HR). Although unclear, this VF might be considered as a form of adrenergic‐dependent long QT syndrome due to early afterdepolarization in the presence of predisposing myocardial conditions.
Malignant Ventricular Tachycardia During Propafenone Treatment in a Child with Junctional Automatic Tachycardia: Effectiveness of Intravenous Molar Sodium Lactate
Authors: SCANU PATRICE , GROLLIER GILLES , GUILLEMAN DANIELE , ISELIN MICHEL , BUSTANY PIERRE , HURPE JEAN‐MICHEL , PC‐TIER JEAN‐CLAUDE
Published: July 2006

Propafenone may aggravate the preexisting arrhythmia or induce another one. Usually, such proarrhythmic effects occur in patients with spontaneous ventricular arrhythmias and/or coronary heart disease with poor left ventricular function. We report the case of a 5‐year‐old girl with Junctional automatic tachycardia and no structural heart disease, in whom malignant ventricular tachycardia occurring during propafenone treatment could be terminated by molar sodium lactate (MSL) infusion. The serum propafenone level obtained before MSL infusion was within the therapeutic range. Two hypothesis could explain the beneficial effects of MSL in our patient: (1) alkalinization facilitates the cell membrane hyperpolarization and thus can decrease the voltage‐dependent effect of Class Ic drugs, (2) alkalinization could displace propafenone from its tissue receptor sites by an increase in the nonionized fraction.
The Relationship Between Heart Rate and QT Interval During Atrial Stimulation
Authors: DICKHUTH H.‐H. , BLUEMNER E. , AUCHSCHWELK* W. , ZEHNDER* M. , IRMER M. , MEINERTZ* T.
Published: July 2006

The relationship between heart rate and QT interval was investigated during atrial stimulation (intrinsic effect of heart rate) in ten healthy male volunteers prior to and after administration of sotaloI. The QT interval in the ECG (paper speed 200 mm/s) was determined at rates of 70, 85, 100, 115, 130, 145, and 160 beats/min and at pacing periods of 180 s each at 30, 60, 120, and 180 s. After a 15‐minute period, 2.0 mg sotalol/kg body weight were administered iv and the stimulation protocol was repeated. The analysis of QT interval behavior reveals contradictions to the mathematical implications of Bazett's equation , so that the relationship between heart rate and QT interval is not adequately described under the given conditions. After examination of approaches reported in the literature and our own approaches, the expression QT = a e−b(HR‐60) is used as a possibility differentially to describe the data by nonlinear regression. The parameters a and b may be interpreted as QT reference value and shortening parameter. The QT reference value a, a parameter in reference to heart rate of 60 beats/min, has a comparable significance to the expression QT, in the Bazett equation. A reduction in the shortening parameter b indicates whether substances influencing the QT interval additionally produce overproportional shortening of the QT interval with increasing heart rate. After administration of sotalol, an increase can be observed in both the QT reference value and also in the shortening parameter. The suggested approach is an attempt to provide a more precise assessment of the QT interval under different conditions.
Quality of Life in Patients with Rate Responsive Pacemakers: A Randomized, Cross‐Over Study
Authors: OTO MEHMET ALI , MÜDERRISOḠLU HALDUN , ǑZIN MEHMET BÜLENT , KORKMAZ MEHMET EMIN , KARAMEHMETOḠLU AYDIN , ORAM AYSEL , ORAM ERDEM , UḠURLU SEVKET
Published: July 2006

Eleven patients with rate responsive pacemakers (7 men, 4 women, mean age 41 years with a range of 23‐60) were randomly assigned to a cross‐over study in order to assess their overall exercise capacity and quality‐of‐life (QOL) scores. All of the pacemakers were implanted for complete AV block or sick sinus syndrome. The pacemakers were randomly programmed into VVI or rate responsive (VVIR) pacing modes for 3‐week study periods in each mode. At the end of each period, an exercise test was performed and the QOL was evaluated by the “Hacettepe Quality‐of‐Life Questionnaire”. All patients exercised longer in the VVIR mode (mean 10.54 ± 0,73 min) than in the VVI mode (mean 7.81 ± 0.62 min) (P < 0.05). QOL scores were also found to be significantly higher in the VVIR mode (mean 173.81 ± 16.22 points) compared to the VVI mode (mean 156.27 ± 21.22 points) (P < 0.01). In conclusion, our results suggest that VVIR pacing offers a better QOL in addition to an improved exercise capacity, compared to the single chamber nonrate modulated pacing (VVI).
Long‐Term Efficacy of an Antitachycardia Pacemaker and Implantable Defibrillator Combination
Authors: BONNET CHRISTOPHER A. , FOGOROS RICHARD N. , ELSON JAMES J. , FIEDLER SUSAN B. , BURKHOLDER JOHN A.
Published: July 2006

Antitachycardia pacemakers and implantable cardioverter defibrillators (ICD) were implanted in 14 patients to control recurrent hemodynamically stable ventricular tachycardia (VT), All patients underwent extensive preimplant testing in the elecrrophysiology laboratory documenting that in each patient at least 50 episodes of VT could be reliably terminated by an external model of the antitachycardia pacemaker. The burst scanning mode of anfitachycardia pacing was used in all patients. ICDs were implanted solely as a back up should acceleration of VT occur, and all had high nonprogrammable rate cutoffs (mean 191 ± 12 beats/min). During a mean follow‐up of 25 ± 6 months, 6,029 episodes of VT were treated in the 14 patients. Only 103 ICD discharges were required (approximately one discharge per 60 episodes of VT). Ten of the 14 patients received discharges from their ICDs. No deaths have occurred. All devices remain active and in the automatic mode. Thus, an antitachycardia pacemaker and ICD combination can safely and effectively terminate VT in highly selected patients who are subjected to extensive preimplant testing. In such patients, the vast majority of episodes of VT can be terminated with antitachycardia pacing, and only rarely is a discharge required from the ICD.
A Comparison of QRS Complexes Resulting From Unipolar and Bipolar Pacing: Implications for Pace‐Mapping
Authors: KADISH ALAN H. , SCHMALTZ STEVE , MORADY FRED
Published: July 2006

To examine differences in QRS configuration produced by bipolar versus unipolar pacing, 12‐Iead electrocardiograms recorded during bipolar (distal cathode) pacing with 5‐ and 10‐mm interelectrode distances were compared to electrocardiograms recorded during unipolar cathodal pacing from the distal catheter pole. Pacing was performed at a cycle length of 500 msec using each of the two bipolar configurations at current strengths equal to late diastolic threshold, twice threshold and 10 mA. The pacing site was at the right ventricular apex in 15 patients and at various left ventricular locations in 14 patients. The electrocardiograms recorded during bipolar and unipolar pacing were compared by two independent observers for minor QRS configuration changes, major configuration changes and amplitude changes. Minor configuration differences between unipolar and bipolar pacing occurred occasionally when the interelectrode distance during bipolar pacing was 5 mm (mean ± S.D. 0.5 ± 1.2 leads per electrocardiogram). However, when the interelectrode distance was 10 mm, minor configuration differences were seen more commonly (1.3 ± 2.0 leads per electrocardiogram; P < 0.05 vs 5‐mm distance). Major configuration differences were uncommon with either configuration at all current strengths. Pacing at 10 mA produced a larger number of configuration differences than pacing at either threshold or twice threshold (P < 0.05). Amplitude differences were seen in a mean of 1.9 ± 2.1 leads per electrocardiogram with the 5‐mm interelectrode distance and a mean of 2.9 ± 2.1 leads using the 10‐mm interelectrode distance (P < 0.05). In conclusion: (1) bipolar ventricular pacing can result in QRS complexes that are different from those obtained with unipolar pacing at the same catheter location, presumably due to an anodal contribution during bipolar pacing; (2) increasing the interelectrode distance and stimulus intensity increases these differences; and (3) because the proximal electrode's contribution to depolarization can alter the QRS configuration during pacing in a variable way, the use of bipolar pace‐mapping to localize sites of origin of ventricular tachycardia may result in Jess spatial resolution than unipolar pace‐mapping.
Sudden Cardiac Death, Implanted Defibrillation, and Clinical Electrophysiology
Authors: COUMEL PHILIPPE , LECLERCQ JEAN‐FRANCOIS , LEENHARDT ANTOINE , SLAMA ROBERT
Published: July 2006

A mere 25 years ago, the technique of external defibrillation became the starting point for the development of clinical electrophysiology by permitting routine use of endocavitary programmed electrical stimulation of the heart without undue risk. Major advances in knowledge of clinical arrhythmias and the understanding of their mechanisms were, thus, permitted. Mirowski's implanted defibrillator also constituted a major breakthrough therapeutically; unfortunately, however, some 10 years later, it has not yet induced similarly hoped for consequences in terms of progressing knowledge concerning lethal arrhythmias, largely due to the absence of Holter functions in the implanted devices. As a result of this, in our opinion, better established therapeutic indications are still needed. The reasons for the present situation, we believe, may be partly technical but are conceptual as well. The key point is that even the clear demonstration of the great practical efficacy of a therapeutic tool does not exempt us from the obligation of determining the mechanisms of this effect.
An Efficient Technique for Implantation of Atrial Leads from the Left Side
Authors: STIRBYS PETRAS P.
Published: July 2006

Implantation of an endocardial lead into the right atrial appendage is itself a simple procedure but may offer complexity if the lead is introduced from the left side of the body. Experimentation on eight corpses allowed determination of an evident method of rapid and reliable implantation of a lead using an S‐shaped stylet. The method has been used successfully in 65 clinical instances.
Utility of Adenosine Administration During Intraoperative Mapping in A Patient with the Wolff‐Parkinson‐White Syndrome
Authors: ELLENBOGEN KENNETH A. , ROGERS REGINA , DAMIANO RALPH
Published: July 2006

Adenosine is an endogenous nucleoside that is administered intravenously and has potent chronotropic and dromotropic effects. This drug is distinguished from verapamil by its very short half‐life. This makes it an ideal agent for use in the operating room where long lasting electrophysiological effects may not he desirable. A 61‐year‐old man with preexcited atrial fibrillation was referred for surgical ablation of his accessory pathway. Preexcitation was minimal or absent on arrival in the operating room. Intravenous adenosine was given causing AV nodal block, and resulted in marked preexcitation, thus allowing computerized mapping to localize the site of the accessory pathway. Adenosine may be a useful agent for rapid and precise localization of accessory pathivay(s) in a select group of patients with minimal preexcitation at the time of surgery. Its short half‐life allotvs additional mapping without sustained electrophysiological effects on the AV node, or accessory pathway.
Diagnosis of Early Cardiac Transplant Rejection by Fall in Evoked T Wave Amplitude Measured Using an Externalized QT Driven Rate Responsive Pacemaker
Authors: GRACE ANDREW A. , NEWELL STUART A. , CARY NATHANIEL R.B. , SCOTT JOHN P. , LARGE STEPHEN R. , WALLWORK JOHN , SCHOFIELD PETER M.
Published: July 2006

Reliable diagnosis of cardiac ailograft rejection is at present only possible using endomyocardial biopsy. We have serially measured epicardial evoked T wave amplitude during ventricular pacing with an externalized QT driven rate responsive pacemaker telemetered to a TP2 analyzer in 13 patients (12 males) followed for 19 (14–26) days after transplantation. A total of 228 records were analyzed. Rejection was defined on endom‐yocardial biopsy. On 17 of the 31 occasions on which biopsy was performed during the study, specimens showed significant (moderate) rejection. In 11 patients the initial biopsy proven rejection episode was associated with a significant fall in the evoked T wave amplitude from 1.3 (0.7–2.3) mV to 0.6 (0.5–1.8) mV (P < 0.005), which began 2 (1–4) days earlier. One patient with uncontrolled diabetes mellitus had no change in evoked T wave amplitude during rejection. The evoked T wave amplitude did not fall in the absence of histologic rejection. These results suggest a noninvasive method for detecting cardiac rejection, which appears both sensitive (92%) and specific (100%) in the first rejection episodes.
Monophasic Action Potential Duration During Programmed Electrical Stimulation
Authors: KANAAN NABIL , JENKINS JANICE , CHILDS KEITH , GE YU‐ZHI , KADISH ALAN
Published: July 2006

To examine changes in monophasic action potential duration (APD) with a pacing protocol similar to that used during electrophysiological testing, action potentials were recorded in vivo from the left ventricular apical endocardium of 12 normal mongrel dogs. The atrioventricular node was ablated and the dogs paced from the anterior right ventricle at a baseline cycle length of 1000 ms between interventions. Mean steady‐state APD (APDSS) was 266 ± 7 ms at a pacing cycle length (PCL) of 1000 ms. Two pacing protocols were used. The first consisted of a sudden acceleration in pacing from a cycle length of 1000 ms to one between 300 and 600 ms. The second consisted of an 8‐beat train at a cycle length of 400 ms followed by a premature beat at a coupling interval of 280 ms followed by a pause. The inter‐train pause varied between 1 second and 32 seconds. With a sudden acceleration in pacing rate, steady‐state values for APD at the faster PCLs were significantly smaller than APDSS at 1000 ms with a change to cycle lengths of 600 ms (247 ± 29 ms), 500 ms (229 ± 21 ms), 400 ms [220 ± 17 ms). and 300 ms (203 ± 31 ms; P < 0.01 for all comparisons). The time constant of the change in APD was shorter at a PCL of 300 ms (14.9 ± 0.8 s) than 600 ms (20.3 ± 4.7 s; P < 0.05). With drive train pacing and incorporating an inter‐train pause, the percent drop in steady‐state APD compared to APD for the first train ranged from 10.1% with a 1‐second inter‐train pause to 2.1% with a 32‐second pause. The difference in APD between the first drive train and drive trains after at least 3 minutes of pacing when APD had stabilized was not significant for an inter‐train pause exceeding 8 seconds. In conclusion: (1) with a sudden acceleration in pacing rate, endocardial APD in vivo decreases exponentially. The faster the new rate, the shorter the new steady‐state APD and the shorter the time constant. (2) When pacing using an 8‐beal drive train and an inter‐train pause, there is a decremental shortening in APD for pause lengths shorter than 16 seconds. Thus, while performing programmed stimulation using a pause, a conditioning period of at least 2 minutes should be used prior to diastole scanning to allow APD to achieve a steady state.
Phase Image Triangulation of Accessory Pathways in Patients Undergoing Catheter Ablation of Posteroseptal Pathways
Authors: OEFF MICHAEL , SCHEINMAN MELVIN M. , ABBOTT JOSEPH A. , BOTVINICK ELIAS H. , GRIFFIN JERRY C. , HERRE JOHN M. , DAE MICHAEL W.
Published: July 2006

The outcome of posteroseptal accessory pathway ablation by direct current (DC) shocks delivered Just outside the so of the coronary sinus was studied in 21 patients. Electrocardiographic and electrophysiological parameters as well as phase image patterns of equilibrium multiple‐gated blood‐pool scintigrams were studied to determine their usefulness in predicting the success of ablation. A second free‐wall pathway was documented by electrophysiological or surgical findings in six patients, and the value of phase images in detecting this second pathway was studied as well. Ablation was successful in 57%. The cumulative mean energy of DC shocks amounted to 524 ± 170 joules and was not predictive of ablation outcome, neither was the mean ventricuioatrial (VA) conduction time. The predictive value of the 12‐lead maximally preexcited electrocardiogram was poor in the 15 patients with a single posteroseptal bypass tract. A new method to triangulate the site of the earliest phase angle on the atrioventricular (AV) valve plane successfully localized the bypass pathway in 14 of those patients. No specific phase pattern predicted successful ablation except for a symmetrical, concentric peripheral phase progression found to be predictive of ablation success in the four patients who showed this pattern. Phase analysis was able to localize the second, nonposteroseptal pathway in four of six patients. This study showed that a concentric peripheral phase progression in the gated blood‐pool scintigrams is predictive for ablation success in patients with posteroseptal pathways. A free‐wall localization of the earliest phase angle is suggestive of a second bypass tract in this area.
Candida Albicans Pacemaker Site Infection
Authors: COHEN TODD J. , PONS VINCENT G. , SCHWARTZ JANICE , GRIFFIN JERRY C.
Published: July 2006

A 69‐year‐old man with a history of diabetes and episodic lymphocytopenia underwent pacemaker implantation for complete heart block. Despite prophylactic antibiotics, pocket irrigation, and strict sterile technique, a fungal (Candida albi‐cans) pacemaker site infection developed that required pacemaker explantation and systemic ampho‐tericin B therapy. After 3 days of temporary pacing, a second pulse generator was implanted on the opposite side. At 2‐year follow‐up, he has had no recurrence of pacemaker infection. This report underscores the predilection of diabetics for infections, and in particular, their susceptibility to Candida albicans.
Natural History of Sinus Node Chronotropy in Paced Patients
Authors: VARDAS P.E. , FITZPATRICK A. , INGRAM A. , TRAVILL C.M. , THEODORAKIS G. , HUBBARD W. , SUTTON R.
Published: July 2006

The natural history of chronotropic incompetence is not clear. To assess this, we evaluated corrected sinus node recovery time (cSNRT) and sinus node chronotropy at rest and during exercise in two groups of syncopal patients with sinus node disease. Group A comprised patients with resting bradycardia but normal cSNRT and group B had resting bradycardia and prolonged cSNRT (> 1000 ms). An additional two groups (C and D) were studied. Group C comprised patients with complete AV (CAVB) and no evidence of sinus node disease and group D were asymptomatic controls of similar age. At diagnosis, patients with symptomatic bradycardia but normal cSNRT and no evidence of carotid sinus syndrome (group A) had resting bradycardia and impaired peak heart rate (PHR‐I) on exercise compared to controls (P < 0.001 and P < 0.05, respectively), but no reduction in exercise duration. At follow‐up group A patients demonstrated an increase in resting rate that was significantly slower than the controls (P < 0.01). Peak heart rate (PHR‐II) also remained significantly slower (P < 0.05). There was no difference in exercise duration between groups A and D at follow‐up. Group B was further subdivided according to follow‐up findings of preservation of atrial activity in seven patients (group B‐1) and junctional rhythm without any atrial activity in four patients (group B‐2). Retrospective analysis showed no significant difference in resting heart rate at initial examination but group B‐2 showed a significantly lower peak heart rate on exercise compared with B‐1 (P < 0.01). Follow‐up exercise tests revealed reduced exercise capacity in B‐2 patients when compared with B‐1 (P < 0.05) and both B‐1 and B‐2 had significantly reduced exercise capacity when compared with control groups C and D (P < 0.001). Group C patients had an initial sinus node chronotropic response to exercise, which was not different from control but significantly better (P < 0.01) than group B. At follow‐up, the mean peak sinus rate of group C patients was unchanged, while there was an insignificant prolongation of cSNRT. Thus, patients with resting bradycardia, blunted peak heart rate response to exercise, and markedly prolonged CSNRT are those most likely to show chronotropic incompetence over the long‐term and should be considered for rate responsive dual (or single) chamber pacing systems.
Differentiation of Arrhythmias by Measurement of Intracardiac Pressures in Man
Authors: BEAUREGARD LOU‐ANNE M. , VOLOSIN KENT J. , WAXMAN HARVEY L.
Published: July 2006

Antitachycardia devices currency use sustained high rate, abrupt changes in cycle length, and probability density function to determine the onset of ventricular tachycardia. Hemodynamic changes occur with the onset of tachycardia and may provide a method of discriminating supraventricular from ventricular tachycardia. In this study, patients had atrial and ventricular pressures measured during rapid atrial and ventricular pacing. Right atrial pressure increased significantly with ventricular pacing but not with atrial pacing. Right ventricular pressures did not significantly differ with atrial or ventricular pacing. The change in atrial pressure compared to baseline was greater, with ventricular pacing compared to atria] pacing. Right ventricular pressure increased compared to baseline with atrial or ventricular pacing, but there was no significant difference between pacing modalities. Measurement of right atrial pressure might prove useful in discriminating supraventricular from ventricular tachycardia.
Efficacy of Ticlopidine in the Prevention of Thromboembolic Events in Patients with VVI Pacemakers
Authors: FAZIO SERAFINO , SANTOMAURO MAURIZIO , CITTADINI ANTONIO , FERRARO SERGIO , LUCARIELLO ANTONIO , MADDALENA GIOVANNI , SACCA' LUIGI
Published: July 2006

This study was designed to evaluate whether long‐term treatment with ticlopidine reduces the incidence of thromboembolie episodes in patients with a VVI pacemaker. One hundred eJeven patients with a VVI pacemaker were randomly assigned to two groups: group A (52 patients) was treated with ticlopidine at the dose of 250 mg a day; and group B (59 patients) was not treated and served as a control group. The primary analysis of efficacy of ticlopidine was based on the occurrence of thromboemboJic episodes and of cardiovascular and cerebrovascular deaths. The mean follow‐up period was 66 months. In group A, there was a significant reduction in the incidence of thromboembolic episodes (P < 0.05) with a smaller incidence of total cardiovascular and cerebrovascular deaths (8 in group A and 18 in group B; P = 0.05) as compared with group B. Twelve percent of patients had moderate side effects with 1 dropout (epistaxis). Our data confirm the high incidence of thromboembolic events in patients with a VVI pacemaker and demonstrate the efficacy of ticlopidine in preventing them.
Benefit of Single Setting Rate Responsive Ventricular Pacing Compared with Fixed Rate Demand Pacing in Elderly Patients
Authors: GAMMAGE MICHAEL , SCHOFIELD STEPHEN , RANKIN IAN , BENNETT MARTIN , COLES PAULA , PENTECOST BRIAN
Published: July 2006

In order to assess the value of a simple, single setting rate response option to VVI pacing, 12 patients (mean age 75.1 ± 6,2, range 62–83 years, seven males, five females) with symptomatic complete heart block were entered into a double‐blind, randomized crossover trial of VVI versus VVIR (single setting rate responsive) pacing using Medtronic Activitrax pacemakers. Assessment was by time taken in seconds (sec) and Borg scale symptom score (6–20) for simple activities (standing from chair x 30; walking 800 meters; 52 steps on stairs [slow and fast pace], and incremental, noninclined maximal treadmill exercise), performed after a 4‐week period with the patient in each pacing mode. Times were significantly improved in VVIR mode for standing from chair [mean ± SD] (78.7 ± 22.5 vs 70.7 ± 19.5 sec; P < 0.05), for 800 m walk (1032 ± 80 vs 885 ± 59 sec; P < 0.05), fast ascent of stairs (29.5 ± 7.7 vs 26.5 ± 5.6 sec; P < 0.02), and treadmill exercise (626.7 ± 189.5 vs 741.0 ± 170.2 sec, P < 0.005) although no difference in time for slow stair ascent was demonstrated. Symptom scores were significantly less in VVIR for standing from chair (12.7 ± 2.8 vs 10.3 ± 1.8; P < 0.01), 800 m walk (10.9 ± 2.7 vs 9.0 ± 2.4; P < 0.01), slow ascent of stairs (11.6 ± 2.1 vs 10.0 ± 2.0; P < 0.01), and fast ascent of stairs (13.0 ± 2.0 vs 11.7 ± 1.9; P < 0.02) but unchanged for treadmill exercise. Single setting VVIR pacing increases maximum exercise capacity and decreases perceived difficulty of submaximal exercise in elderly patients with symptomatic heart block. This would be a beneficial addition to most limited and multiprogrammable VVI systems for use in the elderly.
Anxiety and Depression in Patients with Life‐Threatening Ventricular Arrhythmias: Impact of the Implantable Cardioverter‐Defibrillator
Authors: KEREN RON , AARONS DIANA , VELTRI ENRICO P.
Published: July 2006

In order to assess the psychological responses to the automatic implantable cardioverter‐defibrillator (AICD), 18 patients with a history of life‐threatening ventricular arrhythmias were requested to complete the Spielberger State‐Trait Anxiety Inventory and the Beck Depression Inventory. The patients were divided into three groups of six and matched for age, sex, underlying cardiac disease, ejection fraction, and NYHA Functional Classification. Group I had experienced conscious discharges from the AICD, group II had the AICD but without discharges, and group III without the AICD were treated with antiarrhythmic medications alone based on electrophysiological guided testing. Patients with the AICD were also requested to complete a questionnaire directed specifically at their experiences with the AICD. All of the 18 patients completed the study responses and results were analyzed by blinded review. There were no significant differences in anxiety and depression scores in the three groups studied, nor any significant differences in responses to the questionnaire in group I versus group II. One patient in group I reported experiencing adverse psychological responses to the AICD. Although there appears to be no significant differences in psychological responses as a result of the AICD implantation in patients with life‐threatening ventricular arrhythmias, further study with larger patient groups is needed to identify and support patients who may develop adverse responses to the AICD.
Suppression of Incessant Polymorphic Ventricular Tachycardia by Selective Intracoronary Ethanol Infusion
Authors: OKISHIGE KAORU , ANDREWS THOMAS C. , FRIEDMAN PETER L.
Published: July 2006

Two weeks after an extensive anterior myocardial infarction, a 68‐year‐old man developed incessant polymorphic ventricular tachycardia (PMVT), unresponsive to all conventional treatment modalities. After requiring > 40 direct current cardioversions in < 3 hours, he underwent attempted intracoronary chemical ablation of his arrhythmia as a treatment of last resort. An infusion catheter was positioned selectively in the subtotally occluded left anterior descending (LAD) coronary artery, the putative “tachycardia‐related vessel.” Fifty percent ethanol was delivered to the anterior wall through this catheter by slow, constant infusion. Following selective intracoronary ethanol infusion, spontaneous, unprovoked episodes of PMVT ceased, despite discontinuation of all antiarrhythmic drugs. The LAD remained patent. Several days later, the patient underwent coronary artery bypass surgery and implantation of an implantable defibrillator, succumbing in the early postoperative period from recrudescent intractable ventricular fibrillation and cardiogenic shock. Slow intracoronary infusion of 50% ethanol does not cause abrupt vessel occlusion such as occurs after rapid injection of higher concentrations of ethanol. Selective intracoronary infusion of 50% ethanol may provide temporary lifesaving suppression of otherwise intractable polymorphic ventricular tachycardia.
Sudden Death Mortality in Implantable Cardioverter Defibrillator Patients
Authors: GROSS JAY , ZILO PHILLIP , FERRICK KEVIN , FISHER JOHN D. , FURMAN SEYMOUR
Published: July 2006

Implanfable Cardioverter defibrillator (ICD) prevention of sudden cardiac death (SCD) is not absolute and our experience was reviewed to determine the frequency and nature of SCO in this population. The incidence and cause of mortality in 56 consecutive patients, who underwent ICD implantation beginning May 1982 with follow‐up through May 19, 1990 were analyzed. Twenty‐one patients died, 33% of the mortality was due to SCD, and 52% of deaths may be considered arrhythmic. The cumulative 1, 3, and 5 year SCD survivals were 93%, 89%, and 75%. All seven patients dying of SCD presented initially with SCD, all received previous shocks prior to SCD, and two of the seven patients had devices that were probably inactive at the time of death. We conclude that ICDs reduce but by no means eliminate arrhythmic death, particularly in those at highest risk for SCD. Arrhythmic death remained the most common cause of death in this population.
Clinical Performance of the Implantable Cardioverter Defibrillator: Electrocardiographic Documentation of 101 Spontaneous Discharges
Authors: MALONEY JAMES , MASTERSON MARTIN , KHOURY DIRAR , TROHMAN RICHARD , WILKOFF BRUCE , SIMMONS TONY , MORANT VICTOR , CASTLE LON
Published: July 2006

Records of 105 patients, who received an automatic implantable Cardioverter defibrillator (AICD), were studied to investigate the causes of spontaneous AJCD discharges and to correlate the symptoms with the arrhythmias triggering AJCD discharges. During a follow‐up period of 13 ± 8 months, 46/105 (44%) patients had 566 spontaneous AICD discharges. A total of 101 discharges were documented with Holter monitoring in 23 patients. In this study group, there were 8 (8%) AICD discharges for 5 episodes of ventricular fibrillation, and 68 (67%) discharges for 63 episodes of sustained ventricular tachycardia. Patients lost consciousness in all episodes of ventricular fibrillation, but were symptomatic prior to only 36 (53%) discharges in ventricular tachycardia. Non‐sustained ventricular tachycardia persisting for a period of 7,5 ± 2 seconds resulted in 20 AICD discharges; patients were symptomatic prior to 13 (65%) discharges. Supraventricular tachycardias triggered three discharges. One patient had two spurious discharges during sinus rhythm. In conclusion, most of the spontaneous AICD discharges were appropriate for the detected rhythms, but only clinically appropriate for the management of arrhythmias in 75% of the cases. A significant portion of the patients with sustained or nonsustained ventricular tachycardias triggering AICD discharges were asymptomatic prior to discharge, which requires further assessment of the physiology of the arrhythmia as a component of the detection algorithm.
Survival in Patients with Depressed Left Ventricular Function Treated by Implantable Cardioverter Defibrillator
Authors: AXTELL KATHI , TCHOU PATRICK , AKHTAR MASOOD
Published: July 2006

Mortality in patients with cardiovascular disease is generally due to pump failure or lethal ventricular arrhythmias, In patients with ventricular tachycardia (VT) or ventricular fibrillation (VF) and poor left ventricular (LV) function the death rate is particularly high. The overall incidence of premature arrhythmic death rate in patients with poor LV function is not totally clear. Since implantable cardioverter defibrillator (ICD) could prevent arrhythmic death in any population, we proceeded to analyze mortalities in patients with poor LV function who received ICD. Among a total of 200 consecutive patients receiving ICD at our institution, 68 (34%) had LV ejection fraction (LVEF) of < 30%. Thirty‐one of these (45%) experienced appropriate ICD discharges and 17/31 (55%) had multiple shocks. Survival curves in this population revealed a 5 year projected overall survival of 11% whereas an actual survival was 60%. Even those who ultimately died from nonsudden causes, life was prolonged by ICD in a significant number of cases. Based upon these findings it is concluded that ICD has a major impact on survival in patients with poor LV function suggesting that many of these patients die prematurely from arrhythmia causes.
The Implantable Cardioverter‐Defibrillator: Clinical Results
Authors: PALATIANOS GEORGE M. , THURER RICHARD J. , COOPER DEBORAH K. , GEORGAKAKIS GEORGE E. , TUCKER ROBERT L. , FERNANDEZ PEDRO , Jr ALBERTO INTERIAN , MYERBURG ROBERT J.
Published: July 2006

To evaluate the effectiveness of the automatic implantable cardioverter‐defibrillator (AICD), a 7‐year experience, from 1983–1990, was reviewed. A total of 111 patients received an AICD device. Their ages ranged between 8 and 83 years. Mean age was 63.9 years. There were 91 men and 20 women. Eighty of the patients received the AICD following an out‐of‐hospital cardiac arrest, white 32 were suffering from intermittent symptomatic ventricular tachycardia. The underlying etiology in 97 patients (87%) was ischemic coronary artery disease, in 11 patients (10%) dilated cardiomyopathy, and in 3 patients (3%) idiopathic ventricular fibrillation. Mean ejection fraction was 33.2%. Implantation of the AICD was performed via a left thoracotomy in 39 patients, median sternotomy in 49 patients and subxiphoidsubcostal approach in 23 patients. In‐hospital mortality occurred in one patient who suffered an acute myocardial infarction 4 hours postoperatively. Out‐of‐hospital mortality was observed in 19 patients. There were two arrhythmic deaths. Follow‐up was available for 107 patients. Mean follow‐up was 33.1 months. Sixty‐six patients (62%) had AICD shocks. The initial appropriate shocks occurred during the first postimplantation year in 91% of the patients. In 53 of the survivors, initial AICD shocks took place within 4.4 ± 4.7 months from implantation. Thirteen of the 20 patients who died had received appropriate AICD shocks. In these patients, the time between implantation and first shock was 2.7 ± 3.6 months whereas the time between implantation and death was 11.3 ± 10.3 months (NS). We conclude that the AICD is effective in converting ventricular tachyarrhythmias and prolongs survival.
A Prospective Study Utilizing a Transtelephonic Electrocardiographic Transmission Program to Manage Patients in the First Several Months Post‐ICD Implant
Authors: PORTERFIELD JAMES G. , PORTERFIELD LINDA M. , BRAY LOUISE , SUGALSKI JOHN
Published: July 2006

We prospectively enroled 20 consecutive patients (11 men and 9 women; mean age 63 ± 9.5 years) post‐AICD implant in a transtelephonic electrocardiographic transmission (TET) program. The monitor was chosen for its retrograde (30 seconds) and antegrade memory capabilities (45 seconds). The patients were discharged from the hospital after receiving instructions to utilize the system for any cardiac symptoms. The monitor was worn 1–3 months (mean 2.5 ± 0,7 months). During the follow‐up period there were 54 TETs received. Nine were for documented AICD discharges, 19 were for symptoms associated with arrhythmias (11 of these 19 reported AICD discharges that were not documented), and 26 for symptoms not associated with arrhythmias. Eight of the 9 AICD discharges documented were appropriate for ventricular tachycardia (mean 185 ± 40 beats/min). The arrhythmias associated with symptoms were: atrial fibrillation (12); nonsustained ventricular tachycardia (3); ventricular couplets (2); ventricular premature beats (10); and atrial premature contractions (2). Several TETs documented multiple arrhythmias. The most common symptoms not associated with arrhythmias were shortness of breath, dizziness, chest pain, and nervousness. Office interrogation of the AICDs revealed 12 of the 20 patients (60%) had received AICD discharges, with 5 of these 12 patients unaware of this occurring. We found the TET monitoring system a useful tool in the management of the AICD patient the first several months postoperatively. We were able to assess device function and avoid unnecessary office visits and/or hospitalizations.
Can Changes in Transcardiac Impedance Appropriately Detect Ventricular Fibrillation?
Authors: WEISS STEVEN M. , EINSTEIN ROSEMARIE , McCULLOCH ROY
Published: July 2006

Transcardiac impedance, as measured between two implanted defibrillator patches, has been shown to vary in peak‐to‐peak magnitude in response to the contractions of the ventricles. These variations in transcardiac impedance are known as AZ. This study was aimed at determining if there was a significant change in the magnitude of AZ between that during normal sinus rhythm, that during ventricular fibrillation (VF), and if this change could be used as a detector of the onset of VF. This study was performed acutely on 14 anesthetized dogs.
Comparison Between Two Versus Three Patches Single Pulse Shock Defibrillation in Pigs
Authors: MONTENERO ANNIBALE SANDRO , BOMBARDIERI GABRIELE , BARILARO CYNTHIA , DI FRANCESCO PALMIRO , BERTAZZONI STEFANO , SANTARELLI PIETRO , PISANÓ ENNIO , ALESSANDRINI FRANCESCO , POSSATI GIANFEDERICO
Published: July 2006

The aim of the study was to test the hypothesis that defibrillation with a single pulse shock can be obtained at lower energy using three epicardial patches configuration (one cathode and two anodes) instead of the conventional two patches. The total surface area of the two‐ and three‐patches configuration was the same (10 cm2 vs 9.9 cm2). Epicardial spatial configuration was planned by using a computerized heart model. In ten anesthetized open‐chest pigs, ventricular fibrillation was induced by using AC current through the mesh plaque epicardial custom‐designed electrodes, and the minimum energy requirement for defibrillation was determined 15 seconds after the onset of stable ventricular fibrillation. Results were as follows (mean ± standard deviation):

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Conclusions: three epicardial patches configuration significantly reduces energy requirements for defibrillation compared with two patches when single pulse shock is used.
Catheter Ablation of the Atrioventricular Junction Using a Helical Microwave Antenna: A Novel Means of Coupling Energy to the Endocardium
Authors: LANGBERG JONATHAN J. , WONNELL TRACY , CHIN MICHAEL C. , FINKBEINER WALTER , SCHEINMAN MELVIN , STAUFFER PAUL
Published: July 2006

Catheter ablation with either direct current defibrillator discharges or radiofrequency energy produces tissue injury via current flow from an electrode into the adjacent myocardium. In order to affect tissue at a distance, excessive power density may be produced at the electrode‐tissue interface with the possibility of explosive gas formation or coagulum formation. A novel microwave catheter was developed with a helical antenna distally. This coil, although not in direct contact with the endocardium, radiates an electromagnetic field into the tissue that, in turn, causes thermal injury. The utility of this system for ablation was assessed in six dogs. The antenna catheter was introduced percutaneously and positioned so as to record the largest His electrogram. Microwave power (50 watts at 2,450 MHz) was applied for 114 ± 118 seconds. Complete AV block was produced in all six animals with 1.8 ± 1.2 applications. There was no ventricular ectopy or change in blood pressure during microwave ablation. One dog died 6 days after ablation. The remaining five dogs had persistent, complete AV block during 6 weeks of follow‐up. Pathological analysis at 6 weeks revealed a large (mean 2.8 ± 4.7 mm) fibrovascular scar in the region of the AV junction. Percutaneous microwave ablation of the endocardium appears feasible, By radiating an electromagnetic field without direct contact, this system can produce large lesions without being limited by desiccation of tissue and impedance rise.