bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlations Between the Localization of Accessory Atrioventricular Pathway and Doppler Indices of Left Ventricular Output and Function in Patients With Wolff‐Parkinson‐White Syndrome
Authors: VASKELYTE JOLANTA , BREDIKIS JURGIS
Published: July 2006

Left ventricular (LV) output and function was investigated, using pulsed Doppler echocardiography in 52 patients with various localizations of accessory AV pathway (AP) in sinus rhythm and during paroxysm of AV reentrant tachycardia. In patients with sinus rhythm and ventricular preexcitation the most marked decrease in LV output and function (reduced aortic flow peak velocity (PV), mean acceleration (MA), stroke distance (SD), minute distance (MD), and lengthened time to peak velocity (TTPJ) was noted in the presence of right parietal AP and less marked changes (decreased MA, lengthened TTP)—in the presence of posteroseptal AP, in comparison with the controls (P < 0.005). During antidromic tachycardia the pronounced decrease in PV, MA, SD, and MD was noted, especially in patients with left parietal and posteroseptal AP, while in the case of right parietal AP changes in MA and MD were insignificant. During orthodromic tachycardia the decrease in LV function was less marked and no significant differences in the magnitude of LV output and function changes were found in various localizations of AP, except MA, which was more severely decreased in patients with posteroseptal AP. We conclude, that the alterations in Doppler indices of LV output and function are related to the localization of AP during AV reentrant tachycardia and regular sinus rhythm.
Optimized Hemodynamics by Implantation of a Dual Chamber Pacemaker After Heterotopic Cardiac Transplantation
Authors: BREEDVELD R.W. , VAN GELDER L.M. , MITCHELL A.G. , PEELS C.J. , YACOUB M. , GAMAL M.I.H. EL
Published: July 2006

A patient who underwent prior heterotopic cardiac transplantation had persistent complaints of dyspnea, palpitations, and fatigue in spite of normal pump function of the donor heart. Repeated Holter monitoring excluded paroxysmal arrhythmias. It was thought that synchronization of both heart rates might alleviate his symptoms. The intrinsic heart rate of the donor heart was 90 beats/min, the recipient heart was 60 beats/min with acceleration up to 130 beats/min on exercise. A DDD pacemaker was implanted, the atrial lead was positioned in the right ventricle of the donor heart and the ventricular lead in the atrium of the recipient heart. Search for an optimal AV interval was evaluated by echo‐Doppler and intraarterial pressure recordings. By increasing the AV interval from 125 to 300 msec, the maximum aortic flow velocity of the recipient heart increased from 1.0 to 1.2m/sec. Left ventricular end‐diastolic diameter remained unchanged, left ventricular end‐systolic diameter decreased from 52 to 48 mm. Wall motion of the recipient left ventricle improved. At an AV interval of 125 msec there was alternate systolic contraction of both hearts, resulting in arterial pressure waves at a rate of 180/min. This did not relieve his symptoms and he complained further of headaches. At an AV interval of 300 msec contraction of the recipient heart just preceded that of the donor heart, resulting in arterial pressure waves at a rate o/90/min, normalization of the wave form, relief of symptoms, and improvement of exercise tolerance.
Radiofrequency Catheter Ablation of an Automatic Atrial Tachycardia in an Adult
Authors: KALL JOHN G. , WILBER DAVID J.
Published: July 2006

Automatic atrial tachycardia (AAT) is often refractory to medical management. While surgical ablation and isolation procedures such as atrioventricular node ablation have been useful in the management of AAT, important limitations remain. Reported experience with catheter ablation of AAT is limited. This report describes the successful application of transvenous radiofrequency catheter ablation in an adult with AAT. Potential limitations of catheter ablation in the management of AAT are discussed.
Reproducibility of Successful Drug Trials in Patients With Inducible Sustained Ventricular Tachycardia
Authors: FOGOROS RICHARD N. , ELSON JAMES J. , BONNET CHRISTOPHER A. , FIEDLER SUSAN B. , CHENARIDES JOHN G.
Published: July 2006

Patients whose inducible sustained ventricular tachycardia is suppressed during serial electrophysiological testing have a small but gradually increasing actuarial incidence of recurrent arrhythmias despite therapy with the “successful” drug. In an effort to improve the predictive value of a drug response, in 1990 we began to require that ourfull stimulation protocol be repeated successfully several times before considering a drug to be effective. In 23 consecutive patients who had inducible sustained ventricular tachycardia which was suppressed by at least one drug during invasive serial drug testing using a standard stimulation protocol, the identical stimulation protocol was performed six times during therapy with the initially successful drug (three trials on Day 1 and three trials on Day 2). Repeat trials were completed (i.e., either all six trials were successfully finished or sustained tachycardia was induced) for 29 initially successful drugs in these 23 patients. With 18 of these 29 initiaUy successful drugs (62%), sustained ventricular tachycardia was eventually induced during repeat trials. The eventual drug failures could not be correlated with specific drugs tested, subfherapeutic or falling serum drug levels, marked fluctuations in autonomic tone, or changes in anatomic substrate. The proportion of patients failing each repeat trial was relatively constant: 4/29 (14%) failed Trial 2, 2/25 (8%) failed Trial 3, 7/23 (30%) failed Trial 4, 2/16 (13%) failed Trial 5, and 3/14 (21%) failed Trial 6. The increase in the cumulative incidence of drug failure during repeat trials was nearly linear, Inducibility of ventricular tachycardia appears to be a probability function; a successful drug study should not be regarded as an absolute phenomenon.
Aminophylline Induced Atrial Fibrillation
Authors: VARRIALE PHILIP , RAMAPRASAD SUNIL
Published: July 2006

Atrial fibrillation (AF) with a rapid ventricular response was induced by intravenous [W] aminophyJJine during treatment for symptomatic pulmonary disease in three patients who had no evidence of underlying heart disease or previous cardiac arrhythmia. Serum theophylline concentration was therapeutic in two patients and toxic in the third. Previous reports of AF related to aminophylline have underscored its association with toxic serum theophylline concentration. Conversion to sinus rhythm occurred at a time interval (9–14 hours] appropriate o t the serum decay of aminophylline, after its cessation. A shortened atrial refractory period and dispersed recovery of excitability consequent to aminophylline may engender multiple reentrant circuits and lead to AF, IV diltiazem was more effective than digoxin in the ventricular rate control of AF prior to conversion to sinus rhythm.
Infection of Implantable Cardioverter Defibrillator Systems: A Preventable Complication?
Authors: SHAHIAN DAVID M. , WILLIAMSON WARREN A. , MARTIN DAVID , VENDITTI FERDINAND J.
Published: July 2006

In a consecutive series of 164 patients undergoing primary implantation of an impJantable cardioverter defibrillator (ICD), two patients died in the hospital (1.2%) and early system infection developed in one patient requiring expJantation of the device (0.61%). Late infection developed in one additional patient (0.61%) 7 months after transvenous ICD implantation, and was thought to be due to a recent intravascular catheterization. Symptomatic generator pocket hematomas developed in three patients, two of which were treated by simple evacuation and one with temporary generator explantation and subsequent reimplantation of the unit in a new pocket. No infection developed in these three patients during follow‐up. Generator erosion without obvious system infection developed in a fourth patient. Guidelines for the prevention of infection in ICD systems are presented.
Intracoronary Infusion of Dilute Ethanol for Control of Ventricular Rate in Patients with Atrial Fibrillation
Authors: STRICKBERGER S. ADAM , FOSTER PETER R. , WANG PAUL J. , OKISHIGE KAORU , FRIEDMAN PETER L.
Published: July 2006

The effects of selective infusion of 25% ethanoi into the AV nodal artery was assessed in 1J putients with atriai fibrillation and uncontrollabiy rapid ventricular response rates. The primary study objective was to achieve permaneni modificafion of AV nodal function and control ventricular rate without drug therapy and mthout causing permanent complete AV block. “Clinical success” was defined as drug‐free rate control by either AV nodal modification or the production of complete AV block. Selective catheterization and ethanol infusion into the AV nodal artery could be performed in nine patients. Jntracoronary ethanol infusion acutely caused second‐ or third‐degree AV noda] block in seven palients and an increase in AV nodal refractory period and Wenckebach cycle length in two patients. Acute occlusion of the AV nodal artery or infarction of nontarget myocardium was not observed. During follow‐up of 22.2 ± 2.2 months the primary study objective was attained in only four of nine patienfs treated, yielding an efficacy of 44%. However, the “clinical success” rate was 78%. The acute effects of ethanol on AV conduclion did not predict the chronic effects. Selective intracoronary infusion of dilute ethanol lo control the ventricular rate in atrial fibrillation should be considered when rodiofrequency ablation has been unsuccessful. This method of chemical ablation is as effective and probably safer than rapid administration of 96% ethanol.
Nonuniformity of AH Intervals During Stimulation at Different Left Atrial Sites
Authors: SUZUKI FUMIO , HARADA TOMO‐O , KAWARA TOKUHIRO , TANAKA KAZUSHI , HIRAO KENZO , HIEJIMA KAZUMASA , LEHMANN MICHAEL H.
Published: July 2006

Studies in humans have found left atrial stimulation via the coronary sinus (CS) to elicit significantly shorter atrium‐His (AH) intervals as compared to right atrial stimulation, but whether pacing at dijferent left atrial sites (anterior vs posterior left atrium, i.e., far distal vs proximal CSJ affects the AH interval has not been studied. Hence, in 22 patients, we compared the effects of stimulation from various atriai sites, including anterior high right atrium (HRA), distal CS, mid‐CS, and proximal CS, on; stimulus‐atrium (SA), AH, and stimuIus‐His intervals on the His bundle electrogram. Paced cycle length differed for each patient (range 900–350 msec, mean 532 ± 140 msec), but conduction intervals from different atrial sites were compared using identical cycle length in each patient. The mean SA intervals were 34 ± 10 msec, 57 ± 10 msec, 44 ± 11 msec, and 32 ± 8 msec with stimulation, respectively, from HRA, distal CS, mid‐CS. and proximal CS (each significantly different except for HRA vs proximal CSJ. The mean AH intervals were 123 ± 23 msec, 104 ± 28 msec, 95 ± 15 msec, and 90 ± 18 msec with stimulation, respectively, from HRA, distal CS, mid‐CS, and proximal CS (each significantly different except for mid‐CS vs proximal CSJ. In 13 patients, the discrepancy in AH intervals during distal versus proximal CS stimulation was > 15 msec; in 9 patients this difference was only < 10 msec, considered within the range of measurement error. Thus, in a significant portion of patients, discrepant AH intervals were demonstrated during stimulation from the distal versus proximal CS. These previously undescribed observations suggest that electrophysiological studies on atrioventricular nodal conduction that involve left atrial stimulation must take into account actual location of the stimulation site (anterior or posterior) in order to properly interpret the findings.
Acceleration of Atrial Ectopic Tachycardia as a Guide to Successful Radiofrequency Ablation
Authors: PERRY JAMES C. , FENRICH ARNOLD L. , LEGRAS MARC D. , DENFIELD SUSAN W. , MARLOW DIANNE , ERIEDMAN RICHARD A.
Published: July 2006

Three chiidren with atrial ectopic tachycardia (AET), ages 7–10 years, underwent radiofrequency ablation (RFA). Two had AET localized to the inferolateral orifice of the right atrial appendage, one had AET at the posteroinferior orifice of the left atrial appendage. Each patient received RFA at 15–16 watts for 30 seconds per application. Acceleration of AET rate was observed only during successful RFA application in each palienf. occurring within 5 seconds and Jasfing 2–4 seconds. All unsuccessful applications failed to show this phenomenon. Observation of acceleration of AET rate during RFA was a useful predictor of successful procedure, possibly indicating destruction of abnormally automatic substrates.
Relationship Between Atrial Conduction Defects and Fractionated Atrial Endocardial Electrograms in Patients with Sick Sinus Syndrome
Authors: CENTURION OSMAR ANTONIO , ISOMOTO SHOJIRO , FUKATANI MASAHIKO , SHIMIZU AKIHIKO , KONOE ATSUSHI , TANIGAWA MUNEO , KAIBARA MUNESHIGE , SAKAMOTO RYOJI , HANO OSAMU , HIRATA TETSUYA , YANO KATSUSUKE
Published: July 2006

The relationship between abnormal atrial electrograms (AAE) recorded during sinus rhythm by endocardial calheter mapping of the right atrium and the afrial conduction defects of sinus impulses or single atrial extrastimuli was investigated in 44 patients with sick sinus syndrome. The patients were divided into two groups on the basis of the presence (n = 29) or absence (n = 15) of AAE recorded during sinus rhythm. The P wave duration in the AAE (+) Group patients was 137 ± 14 msec, and 125 ± 15 msec in (he AAE (−) Group; P < 0.02. The intraatrial conduction time of sinus impulses in the AAE (+) Group was 54 ± 12 msec, and 39 ± 9 msec in the AAE (−) Group; P < 0.001. The interatrial conduction time in the AAE (+) Group was 101 + 14 msec, and 78 ± 16 msec in the AAE (−) Group; P < 0.001. In the AAE (+) Group, H (38%) patients ha d a sinus node recovery time > 4 seconds, whereas in the AAE (−) Group there was only one (6%) patient; P < 0.03. AAE showed a specificity of 93% and a positive predictive accuracy of 91% in predicting inducibility of atrial fibrillation. The sensitivity was 35% and the negative predictive accuracy was 42%. Sustained atrial fibrillation was induced in ten (35%) patients of the AAE (+) Group, and in one (7%) patient of the AAE (−) Group; P < 0.05. These data suggest that in patients with sick sinus syndrome who possess abnormal endocardial eJectrograms in sinus rhythm within the right atrium have: (1) a significantly longer P wave duration: (2) a significantly longer intraatrial and interafrial conduction time of sinus impulses; and (3) a significantly greater sinus node dysfunction and higher incidence of induction of sustained atriai fibrillation. It is concluded that there are significantly greater atrial conduction defects in patients with sick sinus syndrome who possess AAE within the right atrium during sinus rhythm.
Improvement of Cardiac Function in Patients with Severe Congestive Heart Failure and Coronary Artery Disease by Dual Chamber Pacing with Shortened AV Delay
Authors: AURICCHIO ANGELO , SOMMARIVA LUIGI , SALO RODNEY W. , SCAFURI ANTONIO , GHIARIELLO LUIGI
Published: July 2006

Medical therapy often fails to control symptoms of severe heart failure. The possibility of modifying to some degree the global ventricular performance with the implantation of a physiological dual chamber pacemaker, set with a short atrioventricular delay (100 msec), has been adopted in two patients with severe heart failure due to coronary artery disease. The baseline clinical condition of both patients was characterized by leg edema, ascites, dyspnea at rest, or even orthopnea with a functional New York Heart Association (NYHA) class III‐IV. Acute measurements of hemodynamic and echocardiographic parameters during stepwise shortening of AV interval guided the pacemaker implantation and setting of AV delay in the chronic phase. Within a few days after pacemaker implantation, both patients considerably improved their clinical status as well as their functional NYHA class, improving to class U in one patient and to class II‐III in the other patient. In addition, modification of systolic and diastoJic parameters paralleled these improvements functional class and clinical condition. Pacemaker therapy in severe heart failure refractory to medical therapy can be of considerable benefit in patients whose quality‐of‐life is severely compromised when pharmacological therapy is no longer effective. Acute hemodynamic and echocardiographic testing is useful in assessing the most appropriate AV delay and pacing mode.
Early Afterdepolarizations in a Patient with Idiopathic Monomorphic Right Ventricular Tachycardia
Authors: NAKAGAWA HIROSHI , MUKAI JUNKO , NAGATA KENJI , KARAKAWA SHINJI , TSUGHIOKA YUKIKO , OKAMOTO MITSUNORI , MATSUURA HIDEO , KAJIYAMA GORO , MATSUURA YUIGHIRO
Published: July 2006

To identify the role of afterdepolarizations in the induction of idiopathic monomorphic right ventricular tachycardia (VT), monophasic action potentials (MAPs) were recorded in a patient with this type of VT. The VT had a left bundle branch block configuration and inferior axis, and originated in the right ventricular outflow tract (RVOT). MAPs were recorded with a contact electrode at the origin of the VT, as well as other ventricular sites. The VT was induced by the intravenous administration of isoproterenol and/or rapid ventricular pacing and was preceded by short‐long‐short sequences of RR intervals. Early afterdepolarizations (EADs) in MAPs were recorded at the origin of VT (RVOT), but not recorded at other ventricular sites. These data suggest that catecholamine sensitive triggered activity seems to be the mechanism of idiopathic monomorphic right VT and EADs can be recorded in association with the occurrence of this type of VT.
Interatrial Conduction in Patients Undergoing AV Stimulation: Effects of Increasing Right Atrial Stimulation Rate
Authors: CAMOUS JEAN‐PIERRE , RAYBAUD FLORENCE , DOLISI CLAUDE , SCHENOWITZ ALAIN , VARENNE ANDRE , BAUDOUY MARCEL
Published: July 2006

To evaluate the frequency of spontaneous or rate dependent interatrial blocks, the interatrial conduction time (IACT) was studied on 100 consecutive patients (mean age 78.3 ±7.8 years) during a transvenous dual chamber pacemaker implant. The spontaneous interatrial conduction time (SIACT) was measured from the intrinsic deflection (ID) of the unipolar right atrial signal to the ID of the left atrial signal recorded in a bipoiar way by an esophageal lead. The paced interatrial conduction time (PIACT) was measured from the stimulus artifact to the left atrial ID, when the atrium was paced at a slightly higher rate than the spontaneous rate and during incremental atrial pacing. From these measurements, the maximum increase ofPIACT (MIPIACT) was deduced. In this elderly population, the PIACT was similar (117 ± 26.9 msec) to the data in the literature. However, there were large interindividual variations that were also found in SIACT. We found a close correlation between SIACT and PIACT (P < 0.0001). PIACT was on average 50 msec longer than SIACT. SIACT increased with age (P < 0.03). The MIPIACT was 15.3 ± 15.2 msec. In the majority of patients, the MIPIACT was > 10 msec, and even reached 90 msec in one patient. MIPIACT was longer in patients with a PIACT exceeding 110 msec (P < 0.004). Based on IACT alone, the AV interval must be lengthened on average by 50 msec when changing from atrial tracking‐ventricular pacing to atrial pacing‐ventricular pacing, but large individual differences must be kept in mind. Elderly people should probably have a longer AV delay.
Intravenous Adenosine Reveals Intermittent Preexcitation by Direct and Indirect Effects on Accessory Pathway Conduction
Authors: MORGAN‐HUGHES N.J. , GRIFFITH M.J. , McCOMB J.M.
Published: July 2006

In some patients with accessory pathways preexcitation occurs intermittently during sinus rhythm. In these patients the antegrade refractory period of the accessory pathway may either exceed the sinus cycle length under some circumstances, or conduction block in the accessory pathway may be variable. The ability of intravenous adenosine to unmask intermittent preexcitation was determined in patients with intermittent preexcitation but absent preexcitalion at the time of study. Six patients undergoing assessment of the Wolff‐Parkinson‐White syndrome received incremental doses of intravenous adenosine (3, 6, and 12 mg). Adenosine administration was repeated in three patients after intravenous β blockade (propranolol 0.2 mg/kg). Adenosine unmasked preexcitation in all patients. P delta intervals with preexcited beats were substantially shorter Ihan resting PR intervals in all cases (range 40–80 msec shorter). In 4/6 patients preexcitation was seen early, coincident with the onset of atrioventricular nodal block. In 4/6 patients preexcitation was seen late during the secondary sinus tachycardia that follows the direct cardiac effects of adenosine. Two patients exhibited early preexcitation and late preexcitation. Beta blockade failed to prevent early preexcitation (2/2 patients) but abolished preexcitation related to sinus tachycardia (3/3 patients). Early preexcitation, coincident with the onset of AV nodal block, suggests a direct effect of adenosine on accessory pathway conduction. Late preexcitation, occurring during secondary sinus tachycardia, and abolished by β blockade, suggests enhanced accessory pathway conduction due to sympathetic activation.
Prognostic Implications of Loss of Late Potentials Following Acute Myocardial Infarction
Authors: KUCHAR DENNIS L. , THORBURN CHARLES W. , SAMMEL NEVILLE L.
Published: July 2006

The prognosis of patients following myocardial infarction is adversely affected by the finding of late potentials at the time of hospital discharge. Loss of late potentials has been previously reported during seriai testing during the first year after infarction, but it is not known whether such patients remain at risk of arrhythmic events. This study prospectively followed 243 patients after myocardial infarction. Late potentials were observed in 92 patients (group 1) at the time of hospital discharge. Of these patients, 23 no longer had late potentials at G‐week follow‐up and 8 had had an arrhythmic event (sudden death or ventricular tachycardia). In patients with loss of late potentials, overall QRS duration had decreased from 109 ± 11 msec at discharge to 104 ± 11 msec (P < 0.01), terminal QRS voltage rose from 15 ± 4 μV to 31 ± 9 μV (P = 0.001), and late potential duration fell from 42 ± 6 msec to 28 ± 6 msec (P = 0.001) at the 6‐week study. Predictors of loss of late potentials were: initial duration of the QRS duration (P < 0.001) and terminal voltage (P < 0.005); non‐Q wave infarction (P < 0.001); and being a male (P < 0.05). After the 6‐week assessment, 11 additional arrhythmic events occurred during median follow‐up of31 months. The risk of arrhythmic events was similar in patients with loss of late potentials and those who retained late potentials in group I (9% vs 11%, P ‐ NS) but significantly greater than palients with no late potentials at discharge (group II, 2%). Of those patients with events beyond 6 weeks, a normal signal‐averaged ECG (either lost late potentials or group II) was observed in 6/11 (55%) patients on at least one occasion prior to the occurrence of the event. Hence, a significant number of arrhythmic events occurring ≥ 6 weeks after myocardial infarction occur in palients with a normal signal‐averaged ECG even when late potentials are initially present. “Loss’ of late potentials does not necessarily confer an improved prognosis in terms of risk of arrhythmic events.
Prediction of Arrhythmic Events After Acute Myocardial Infarction Using Two Methods for Late Potentials Recording
Authors: STRASBERG BORIS , ABBOUD SHIMON , KUSNIEC JAIRO , INBAR SHULA , ZAFRIR NILI , MAGER AVIV , SAGIE ALIK , SCLAROVSKY SAMUEL
Published: July 2006

One hundred consecutive patients recovering from an acute myocardiai infarction underwent, prior to home discharge, signal‐averaged electrocardiography (ECG), left ventriculography. and 24‐hour Holter ECG recording. The signal‐averaged ECG was recorded and analyzed using two procedures: the orthogonal bipolar XYZ lead configuration with a bidirectional filter: and a precordial unipolar lead configuration with a uonrecursive digital filter. An abnormal signal‐averaged ECG was seen in 40% of patients with the XYZ system and in 30% of patients in the precordial method, abnormal ejection fraction (< 40%) in 24% of patients and high grade ectopy activity in 22%. During the 24‐month follow‐up period, 12 patients (12%) had an arrhythmic event defined as either sudden death (11 patients) or sustained ventricular tachycardia (1 patient). Neither the signal‐averaged ECG with the XYZ configuration, the abnormal ejection fraction, nor the high grade ectopy were able to statistically predict a higher arrhythmic event rate. The signal‐averaged ECG with the precordial configuration was able to statistically predict a higher arrhythmic event rate, P < 0.03; odds ratio = 3.96. The combination of the orthogonal XYZ configuration signal‐averaged ECG with the ejection fraction (P < 0.01, odds ralio = 7.33), or with ejection fraction and Holter monitoring (P < 0.06. odds ratio = 6.17) was able to predict a higher arrhythmic event rate. The combination of the precordial configuration signal‐averaged ECG with the ejection fraction (P < 0.002, odds ratio = 14.4), or with ejection fraction and Holter monitoring (P < 0.06. odds ratio =10) was able to better predict a higher arrhythmic event rate. The combination of a normal or abnormal signal‐averaged ECG and ejection fraction gave a sensitivity, specificity, positive, or negative value prediction of arrhythmic events of 60%, 90.6%, 37.5%, and 96%, respectively. It must be emphasized that the number of arrhythmic events during the 2‐year follow‐up was small and further study is required to determine the true predictive value of each method for arrhythmic events.
Influence of a Third Extrastimulus in Deflning Effective Drug Therapy During Serial Electrophysioiogicai Testing
Authors: MANN DAVID E. , KELLY PATRICIA A. , FUENZALIDA CHARLES E. , REITER MICHAEL J.
Published: July 2006

Many electrophysiology laboralories use three extrastimuli in all patients with ventricular tachyarrhythmias during antiarrhythmic drug testing, regardless of the mode of arrhythmia induction in the baseline state. The purpose of this study was to compare this pacing protocol (full protocol) with a protocol in which three extrastimuli were only used during drug tests, if they were required in the baseline state for arrhythmia induction (limited protocol). There were 181 electrophysiology lests performed on 69 patients with ventricular tachyarrhythmias that were retrospectively analyzed. In all studies the full protocol was used, but the results of stimulation were also analyzed assuming the limited protocol had been used. In the baseline state, sustained ventricular tachyarrhythmias were reproducibly inducible with one or two extrastimuli in 38 (55%) patients. Of these patients, six (16%) achieved a drug efficacy prediction using the full protocol versus 15 (39%) patients using the limited protocol (P < 0.001). In all 69 patients, the drug response rate increased from 25% to 38% (P < 0.01) using the limited protocol. Overall, the cycle length of induced ventricular tachycardia during drug testing was longer than during baseline testing (352 ± 8vs 296 ± 7 msec, P < 0.001); however, the cycle length of ventricular tachycardia induced by three extrastimuli during drug restudies in patients in whom tachycardia had only required one or two extrastimuli to induce in the baseline state was not significantly different from the baseline tachycardia cycle length (303 ± 15 vs 318 ±11 msec, P = NS). and was significantly shorter than the cycle length of tachycardia induced by one or two extrastimuli during drug testing (303 ± 15 vs 385 ± 15 msec, P < 0.01). Using three extrastimuli in all patients during drug testing decreases the yield of drug efficacy predictions, but whether predictive value is improved or made worse cannot be answered from this study.
Radiofrequency Ablation Therapy in Three Patients with Paroxysmal Atrial Tachycardia
Authors: WEN MING‐SHIEN , YEH SAN‐JOU , WANG CHUN‐CHIEH , LIN FUN‐CHUNG , WU DELON
Published: July 2006

Radiofrequency ablation therapy was performed in three patients with paroxysmal atrial tachycardia. There were two females and one male, aged 80, 63, and 75 years, respectiveiy. All three patients had induction of sustained atrial tachycardia. The tachycardia could be terminated by overdrive atrial pacing or atrial premature stimulation; it could also be terminated by intravenous bolus of adenosine triphosphate. In all three patients, there was no fragmented atrial electrograms recorded within the right atrium, and there was no ventriculo‐atrial conduction during ventricular pacing. Tiie earliest atrial activation during tachycardia in these three patients was registered, respectively, at a site slightly posterior and inferior to the His‐bundle recording site, at the anterior‐superior border of Koch's triangle slightly posterior to the His‐bundle recording site, and at the mid‐lateral aspect of the right atrium over the crista terminalis at the junction of right atrial appendage and sinus venarum. Radiofrequency current was deiivered to the site of the earliest atrial activation during tachycardia through a 4‐mm tip electrode catheter. It resulted in termination of tachycardia and ablation of the tachycardia focus. FoIIow‐up observation over a period of 16, 15, and 4 months, respectively, in these three patients showed no recurrence of tachycardia. A repeat eiectrophysiological study was performed 52 and 63 days after ablation in two patients and revealed no induction of atrial tachycardia.
Premature ICD Battery Depletion Due to a Defective Lead Adapter Component: Usefulness of Extensive Data Logging
Authors: CANDINAS RETO , HAGSPIEL KLAUS D. , MacCARTER DEAN J. , NIEDERHÄUSER URS , AMANN FRANZ W. , TURINA MARKO
Published: July 2006

Described herein is the usefulness of extensive data logging of third generation ICDs in a patient with premafure ICD battery depletion due to a defective pace/sensing lead component. Due to noise artifacts, VT/VF detections occurred leading to inappropriate patient shock discharges and 2,267 internal charge dumps within 2 weeks. During manual manipulations at the ICD site, real‐time intracardiac eJectrocardiogram and event markers revealed noise artifacts that were interpreted as VT/VF. Radiography confirmed slight movement of the pace/sensing lead pin out of the Y‐adapter. Therefore, the design of adapter systems without screw fixation should be reviewed to ensure lead integrity. In the case of sudden increases in VT/VF recognition, defective sensing components must be considered.
Resolution of Atrial Standstill in a Child with Myocarditis
Authors: STRAUMANIS JOHN P. , WILES HENRY B. , CASE CHRISTOPHER L.
Published: July 2006

Atrial standstill is a rare disorder usually seen in adults with extreme myocardial disease. Etiologies described in the literature have included muscular dystrophy, familial amyloidosis, and rarely myocarditis. These etiologies usually lead to permanent atrial slandslill and require ventricular pacing. We present a case of an 11‐year‐old black female who developed atrial standstill secondary to biopsy proven acute necrotizing myocarditis. Absence of atrial function was confirmed by surface electrocardiogram, echocardiogram, and an invasive electrophysiology study. Atrial function returned within 3 days of initiation of methyl‐prednisolone. In cases of atrial standstill due to myocarditis, a delay in the placement of a permanent pacemaker with or without a trial of methylprednisolone may prove beneficial.
Radiofrequency Catheter Ablation of Sinus Node Reentrant Tachycardia
Authors: SPERRY ROBERT E. , ELLENBOGEN KENNETH A. , WOOD MARK A. , BELZ MICHAEL K. , STAMBLER BRUCE S.
Published: July 2006

Sinus node reentrant tachycardia is a relatively uncommon (5%‐5%) form of recurrent paroxysmal supraventricular tachycardia (SVT). We describe a case of symptomatic sinus node reentrant tachycardia in a 67‐year‐old male with ischemic heart disease, congestive heart failure, and depressed ventricular function. Adenosine administered during an electrophysiology study caused prolongation of the tachycardia cycle length due to atrial cycle length prolongation (without atrio‐His prolongation) prior to tachycardia termination. Right atrial mapping revealed the earliest site of atrial activation in the high lateral right atrium just below the superior vena cava. Low energy (10 and 20 W) radiofrequency lesions were applied ai this site with termination of the tachycardia within 3 seconds of radiofrequency energy delivery. Tachycardia could not be reinduced after delivery of the radiofrequency lesions. The sinus node function immediately and 6 weeks after radiofrequency catheter ablation remained normal and the patient was without clinical recurrence of SVT. Mapping of sinus node reentrant tachycardia and elimination of the reentrant circuit with radiofrequency catheter ablation is possible without causing sinus node dysfunction. Adenosine causes prolongation of the atrial cycle length followed by termination of sinus node reentrant tachycardia.
Technical and Clinical Problems in Patients with Simultaneous Implantation of a Cardiac Pacemaker and Spinal Cord Stimulator
Authors: ROMANÓ MASSIMO , ZUCCO FURIO , BALDINI MARINA ROTA , ALLARIA BIAGIO
Published: July 2006

Spinal cord stimulators are used to relieve pain associated with peripheral ischemia and angina pectoris. In patients with both a permanent pacemaker (PPM) and a spinal cord stimulator (SCS), electromagnetic signals from the SGS may inhibit the PPM. A bipolar PPM configuration is preferred to minimize myopotential or electromagnetic interference but patients have safely had unipolar devices implanted. We report ten patients (six males and four females; median age 73.3 years) with both a SCS and a PPM implanted between 1987–1991. Intermittent interference with one PPM (Ela Medical Model Opus 3001)was noted after an increase in the output voltage of the SCS for continued clinical efficacy. Inhibition was output voltage dependent, and reversion to the noise mode was frequency dependent. Sensitivity to both could he managed by changing the pacemaker sensitivity. Interference with pocemaker function occurred if the SCS output was set above a voltage and pulse duration which resulted in a product of these values above 1.9–2 mVs. Seven VVI, one VDD, and two DDD PPM had been implanted. In five potients hoth PPM and SCS were unipolar. In two patients the SCS was bipolar and the PPM unipolar, in two potients a bipolar PPM was associated with a bipolar SCS and with one patient, a unipolar SCS. Multiprogrammable and/or bipolar PPMs should be implanted in a patient with a SCS to allow reprogramming of the PPM and to minimize the risk of inter‐device interference. Inhibition of the PPM may occur at different SCS stimulation frequencies. The frequency at which inhibition occurs varies with different models of implanted pacemaker
Rate Responsive Cardiac Pacing Using a Minute Ventilation Sensor
Authors: ABRAHAMSEN ARNE M. , BARVIK STÅLE , AARSLAND TORBJØRN , DICKSTEIN KENNETH
Published: July 2006

A minute ventilation sensing rate responsive pacemaker was implanted in 15 patients (8 males and 7 females)with bradycardia. The mean age was 72.8 ± 8.7 years. The single chamber system measures transthoracic impedance between the tip electrode of a standard bipolar lead and the pulse generator case. In the adaptive mode the pulse generator calculates a rate responsive factor or slope during maximal exercise but /unctions as in the VVI mode. The patients exercised maximally on an upright cycle ergometer with the pacemaker programmed to VVI mode, adaptive mode, and rate responsive mode. Exercise and gas exchange data were collected continuously and analyzed using an automated breath‐by‐breath system. The slope, heort rate, and ventilation were measured every 20 seconds. Heart rate in pacemaker dependent patients correlated well to minute ventilation (correlation coefficient ranging from 0.72–0.95, P < 0.0001). This study demonstrates that minute ventilation is a good metabolic sensor in rate responsive pacing.
Effects of Acute Ischemia on Anisotropic Conduction in Canine Ventricular Muscle
Authors: MIZUMAKI KOICHI , FUJIKI AKIRA , TANI MASANAO , MISAKI TAKURO
Published: July 2006

The effects of acute ischemia on conduction velocities in the longitudinal (θL)and transverse (θT)fiber axis were determined from epicardiai activafion patterns, recorded with 48 bipolar electrodes (piaque eiectrode, 25 × 35 mm) on the left anterior ventricuiar wail of eight dogs and the posterior wall of seven dogs. During left ventricuJar stimulation (cycle length = 300 msec)in the center of the piaque electrode, θL, θT, and the ratio of longitudinai to transverse conduction velocities (θL/t)were measured before and 2 to 5 minutes after occiusion of the left anterior descending coronary artery or the left circumflex coronary artery. During the control state θLwas greater thon θTdemonstrating anisotropic properties of cardiac muscle, not only in the anterior but also in the posterior wail. During acute ischemia θL and θTwere decreased from the control value and θT was decreased by a greater extent than θL, resuiting in an increase in θL/Tfrom 1.83 ± 0.31 (mean ± SD)to 2.19 ± 0.36 in the anterior wall and from 1.58 ± 0.17 to 1.92 ± 0.28 in the posterior wall. During ventricuiar fibriiiation some lines of conduction block were parallel to the long axis of epicardial muscie fiber bundle and the others were perpendicular. In conclusion, acute ischemia increased anisotropic conduction (Bl/t) in the epicardial ventricular muscle mainly due to greater reduction in θT, in the anterior and the posterior wall. This augmented anisotropic ventricuiar conduction may have some relation to the initiation of ventricular fibrillation during acute ischemia.
Ventilation and Heart Rate Response During Exercise in Normals: Relevance for Rate Variable Pacing
Authors: TREESE NORBERT , MacCARTER DEAN , AKBULUT OMAR , COUTINHO MARIO , BAEZ MARCHENA , LIEBRICH ANDREAS , MEYER JÜRGEN
Published: July 2006

The observation of a close relationship of heart rate to oxygen uptake (HH‐VO2) and heart rate to minute ventilation (HR‐VE)has been shown to be of particular value in rate variable pacing. However, the impact of anaerobic threshold (AT)for the HH‐VO2 and HH‐VE slope has been studied Jess. Twenty‐three male and 16 female subjects, mean age 52 ± 7 years, were selected in whom complete heart catherization and extensive noninvasive sludies excluded major cardiopulmonary disease. Semisupine bicycle exercise testing with analysis of respiratory gas exchange was performed using a ramping work rate protocol with work increments of 20 watts/min. At the respiratory AT, determined by the V slope method, oxygen uptake (VO2‐AT)was 15.2 ± 3.0 mL/kg in males versus 13.8 ± 2.3 mL/kg in females and heart rate (HR‐AT)was 109 ± 18 beats/min versus 119 ± 20 beats/min, respectively. Heart rate was highly correlated (r ±0.9)to VO2 and minute ventilation (VE). A linear regression for HR‐VO2, however, was found only in 16/39 and for HR‐VE in 11/39 subjects. Assuming the AT as the breakpoint of two linear curves, it could be demonstrated that compared to low exercise HR appeared to increase at maximal exercise more in relation to VO2 but less in relation to VE; in men the individual slopes for HR‐VO2 were 2.6 ± 0.7 below but 3.2 ± 1.0 above AT (P < 0.05) and the slopes for HH‐VE were 1.6 ± 0.5 below but 1.0 ± 0,4 above AT (P < 0.05). Similarly, in women the individual slopes for HR‐VO2 were 3.7 ± 1.4 below but 4.3 ± 1.4 above AT (P < 0.05)and the slopes for HR‐VE were 2.1 ± 0.9 below but 1.3 ± 0.4 above AT (P < 0.05). The differences between male and female subjects were significant. The nonlinear behavior of the HB‐VO2 and HR‐VE relation from rest to maximal exercise should have a particular impact in respiratory controlied pacing systems.
Beat‐to‐Beat Variability in Stroke Volume During VVI Pacing as Predictor of Hemodynamic Benefit from DDD Pacing
Authors: DRITSAS ATHANASE , JOSHI JAYSHREE , WEBB STUART C. , ATHANASSOPOULOS GEORGE , OAKLEY CELIA M. , NIHOYANNOPOULOS PETROS
Published: July 2006

To determine whether the magnitude of Beat‐to‐Beat variability in stroke volume (SVJ during VVI pacing can predici hemodynamic benefit from DDD pacing, we undertook Doppier recordings of systolic and diastolic LV flow during VVI and DDD pacing in 20 patients (age 54 ± 9 years)with DDD pacemakers implanted due to AV block. SV increased by 19%± 10% from VVI to DDD (P < 0.01). This increase was greater (29%± 9%)in patients with a ratio of early (E)/late (A) filling < 1 compared to those with E/A > 1 (10%± 9%) (P < 0.001). Beat‐to‐Beat variability in SV was greater in VVI (13%± 8%)compared to DDD (4%± 1%) (P < 0.001). Patients with E/A < 1 showed greater Beat‐to‐Beat variability in SV during VVI pacing (19 ± 6%)compared to those with E/A > 1 (8%± 4%) (P < 0.001). Beat‐to‐Beat variability in SV during VVI pacing correlated with both percent change in SV from VVI to DDD (r = 0.89, P < 0.001)and E/A (r = ‐0.71, P < 0.001). In conclusion, patients with E/A < 1 derive greater hemodynamic benefit at rest from DDD pacing compared with E/A > 1. In addition, patients with complete AV block who show large variations in SV during VVI pacing may obtain greater hemodynamic benefit at rest from DDD pacing than patients with small variations.
Effective Defibrillation in Pigs Using Interleaved and Common Phase Sequential Biphasic Shocks
Authors: GUSE PAUL A. , ROLLINS DENNIS L. , KRASSOWSKA WANDA , WOLF PATRICK D. , SMITH WILLIAM M. , IDEKER RAYMOND E.
Published: July 2006

Previous studies have shown that low internal de/ibrillation threshoids (DFTs)can be attained by using two pairs of electrodes and combining hiphasic shocks with sequential timing. The purpose of this two‐part study was to test the defibrillation efficacy of two new shock sequences, an interleaved biphasic. and a common phase sequential biphasic, that utilized two pairs of electrodes and were developed from the concept of sequential biphasic shocks. In the first part, defibriUation catheters were placed in the right ventricle and the superior vena cava of six anesthetized pigs. A small patch electrode was placed on the LV apex through a subxiphoid incision and a cutaneous patch was placed on the left thorax. The mean DFT energies for the interleaved biphasic (5.2 ± 0.4 J)and the common phase sequential biphasic waveforms (5.4 ± 0.4 J)were substantially less (P < 0.0001)than those for either the sequential monophasic (10.6 ± 1.0 J)or single biphasic waveforms (9.0 + 1.0 J). In (he second study, which used nine anesthetized pigs, the importance of phase reversal was demonstrated by the finding that Ihe DFT energy of a common phase sequential biphasic shock (6.2 ± 0.4 J)was much less than a common phase sequential monophasic shack (17.9 ± 1.3 J, P < 0.0001), furthermore, the average DFT for four common phase sequential biphasic configurations (5.7 ± 0.2 J)was much less than for a configuration that was similar except that current flow was not reversed in one phase so that no biphasic effect was present (19.7 ±1.2 J). The efficacy of common phase sequential biphasics was comparable to that of sequential biphasics. The effectiveness of sequential biphasics, interleaved biphasics, and common phase sequential biphasics is possibly due to two mechanisms: (A)an increase in the potential gradient during a later phase in regions that were low during the first phase, and (B)the exposure of most of the myocardium to a biphasic shock that reduces the minimum extracellular potential gradient needed to defibrillate.
Managed Care and Cardiac Pacing and Electrophysiology
Authors: MILLS PENNY S. , MICHNICH MARIE E.
Published: July 2006

Managed care is having an increasing impact on the administrative and clinical practices of cardiovascular specialists including physicians providing cardiac pacing and electrophysiology services. This article provides an overview of the five key areas where managed care is affecting cardiovascular practices including the following: (1) administrative burdens; (2) competitive/economic pressures; (3) cost/efficiency requirements; (4) interference in the physician‐patient relationship; and (5) disruption in physician‐physician relationships. The issues associated with each of these areas of concern are discussed in detail with specific examples that are relevant to cardiac pacing and electrophysiology. (PACE, Vol. 16, August 1993) managed care. Health Maintenance Organizations (HMOs), Preferred Provider Organizations (PPOs)
Provocation of Atrioventricular Reentry Tachycardia: A Paradoxical Effect of Adenosine
Authors: DOUGHERTY ANNE HAMILTON , GILMAN JAMES K. , WIGGINS STANLEY , JALAL SOHAIL , NAGGARELLI GERALD V.
Published: July 2006

Adenosine has been used to diagnose latent preexcitation in patients with the Wolff‐Parkinson‐White syndrome. A case is reported in which intermittent preexcitation had been previously observed, however only retrograde accessory pathway conduction was documented at the time of invasive eiectrophysiological study, Administration of intravenous adenosine during sinus rhythm resulted in provocation of orthodromic atrioventricular reentry tachycardia.
Ethanol Increases Defibriliation Threshold in Pigs
Authors: KIM YOU HO , JONES DOUGLAS L. , NATALE ANDREA , KLEIN GEORGE J.
Published: July 2006

Alcohol ingestion has been associated with cardiac arrhythmias and may initiate fibrillation in patients with automatic defibrillators. The effect of alcohol on defibriliation efficacy is unknown. To assess the acute effects of alcohol on defibrilia‐tion efficacy, triplicate defibrillation thresholds (DFTs) were determined before and after intravenous administration of 25% ethanol. Fifty‐two pigs were randomized into four groups: (1) control, 6 mL/kg of saline over 10 minutes (n = 12); (2) low dose, 6 mL/kg of 25% ethanol over 10 minutes (n = 12); (3) mid dose, 0.45 mL/kg per minute for 30 minutes followed by 0.045 mL/kg per minute for 45 minutes (n = 12); and (4) high dose, 0.45 mL/kg per minute for 30 minutes followed by 0.06 mL/kg per minute for 45 minutes (n = 16). Three coil defibrillating electrodes (Medtronic 6888) were sutured to the epicardium of the right and left ventricles for de/ibrillation shocks. Ventricular fibrillation was induced using alternating current and after 10 seconds of fibrillation, the minimum energy for defibriliation was established using sequential pulse defibriliation. Triplicate determinations were obtained before and after saline or ethanol infusion. Alcohol elevated DFT in a dose related manner. Control and low dose groups thresholds were unchanged, but the mid dose approached statistical significance (6.8 ± 0.7 vs 7.6 ± 0.9 J, 0.05 < P < 0.1)and the high dose was significantly elevated (8.5 ± 0.7vsll.2 ± 1.1 J. P < 0.01). Ventricular effective refractory periods and cycle lengths between fibrillatory waves did not differ before and after the high dose ethanol. These results indicate that high blood levels of ethanol impoir defibriliation efficacy and may result in failure to defibrillate patients with borderline DFTs.
Early Afterdepolarization in a Patient with Complete Atrioventricuiar Block and Torsades de Pointes
Authors: KURITA TAKASHI , OHE TOHRU , SHIMIZU WATARU , HOTTA DAISUKE , SHIMOMURA KATSURO
Published: July 2006

We present a patient with complete atrioventricuiar block and torsades de pointes in whom earJy afterdepolarization (EAD) was demonstrated in right ventricular monophasic action potentials (MAPs). In an emergency situation, MAPs were recorded after the suppression of torsades de pointials magnesium injection. EADs were observed at three out of five right ventricular sites during escape rhythm. Thus, magnesium aboJisiied the tachycardia without shortening the QT interval and probably without suppressing EAD. Right ventricular pacing and the injection of lidocaine (50 mg) suppressed EAD and shortened the QT interval.