bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonfluoroscopic Guidance for Catheter Placement into the Coronary Sinus under Direct Vision Using a Balloon‐Tipped Cardioscope
Authors: YAMAMOTO NAOHITO , HIRAO KENZO , TOSHIDA NOBUO , NAWATA HIROKO , SUZUKI FUMIO , MIYASAKA NOBUYUKI , HIEJIMA KAZUMASA
Published: July 2006

The right atrial posterior septum, including the coronary sinus (CS) ostium, is an important landmark in radio frequency catheter ablation therapy for supraventricular tachycardia or atrial flutter. The anatomical findings around the CS ostium would be useful to determine a target site or line during catheter ablation. The aim of the study was to test the ability of the imaging catheter to identify structures in the posterior septal area of the right atrium and to evaluate the feasibility of guidance for catheter placement in the CS using a cardiosccpe that we recently developed. In 12 anesthetized dogs, the Cardioscope, consisting of a deflectable 7 Fr fiberoptic endoscope with an inflatable and transparent balloon, was introduced into the right atrium via the femoral vein. The cardioscope was manipulated to observe the right atrial posterior septum. A deflectable electrode catheter was inserted via the jugular vein and positioned in the CS under cardioscopic guidance. In 10 of 12 dogs, the right atrial posterior septum, including the CS ostium, and the tendon of Todaro could be anatomically identified by cardioscopy. It was possible to position an electrode catheter in the CS in all 10 dogs under direct vision without fluoroscopy. But the CS ostium could not be detected in the remaining two dogs, although the cardioscope was placed at as many sites as possible. No complication occurred. The balloon‐tipped cardioscope appears to be useful in observing the right atrial posterior septum and in guiding an electrode catheter into the CS.
Outpatient Pacemaker Procedures in Orally Anticoagulated Patients
Authors: GOLDSTEIN DANIEL J. , LOSQUADRO WILLIAM , SPOTNITZ HENRY M.
Published: July 2006

Reexamination of surgical practices in the present era of cost containment has led to increased outpatient procedures including pacemaker surgery. While the safety and economic benefits of outpatient pacemaker surgery in nonanticoagulated patients is well documented, results of pacemaker operations in patients maintained on coumadin for thromboembolic prophylaxis have not been evaluated. In patients where complications with pacemaker surgery appeared successive, we have established a low incidence of complications. Recently, we extended this approach to the outpatient setting; this report retrospectively reviews our 4‐year experience. During the study period, 150 patients underwent outpatient pacemaker procedures, including 37 patients receiving oral warfarin. There was no difference in the incidence of wound related and wound unrelated complications between patients receiving warfarin and the nonanticoagulated cohort. In addition, no wound hematomas, blood transfusions, or clinically significant bleeding episodes were noted among warfarin recipients. We conclude that pacemaker surgery in patients receiving oral anticoagulation is safe and feasible. The use of the cephalic cutdown technique avoiding blind subclavian punctures, meticulous attention to pocket hemostasis, and the use of small caliber unipolar positive fixation leads appears warranted in this selected group of patients at high risk for perioperative bleeding.
Fluoroscopic Determination of Latissimus Dorsi Muscle Shortening Fraction after Dynamic Cardiomyoplasty
Authors: MONNET ERIC , ORTON E. CHRISTOPHER , JACOBS GORDON , METELMAN LISA
Published: July 2006

Optimization of the skeletal muscle contraction during cardiac assist is important to achieve maximal cardiac assist and yet avoid overstimulation that may injure skeletal muscle. Dynamic Cardiomyoplasty suffers from lack of an objective, reproducible, and accurate technique to measure skeletal muscle shortening fraction after wrap and training of the muscle. A recruitment curve is considered the best way to select the proper stimulation level to achieve supramaximal contraction without overstimulating the muscle. A fluoroscopic technique of determining latissimus dorsi recruitment cuive was evaluated in five goats undergoing dynamic Cardiomyoplasty with an anterior cardio–subcutaneous wrap. Two pairs of stainless steel targets (0.5 and 1 cm of diameter) were implanted on each side of the muscle wrap. One pair of sonomicrometer crystals was also implanted. Displacement of the targets was measured under fluoroscopy at five different stimulation levels. Correlation coefficients between targets on the inside surface of the wrap and the sonomicrometer crystals, and targets on the outside surface of the wrap and the sonomicrometer crystals were 0.71 (P ± 0.05) and 0.60 (P ± 0.05), respectively. Targets on the inside surface of the wrap were more accurate than targets on the outside surface of the wrap for measurement of skeletal muscle shortening fraction and establishment of a recruitment curve. Adverse effects from the targets were not observed.
Prevention of Atrial Arrhythmias during DDD Pacing by Atrial Overdrive
Authors: GARRIGUE STÉPHANE , BAROLD SSERGE , CAZEAU SERGE , GENCEL LAURENT , JAÏS PIERRE , HAISSAGUERRE MICHEL , CLÉMENTY JACQUES
Published: July 2006

We evaluated the effect of atrial overdrive on the incidence of atrial arrhythmias (AA) in 22 patients (67 ± 9 years. 7 women, 15 men) with Chorus 6234 DDD pacemakers. Atrial overdrive was defined as a programmed paced rate 10 ppm faster than the mean ventricular rate stored for the last 24‐hour period in the pacemaker memory. The protocol consisted of three phases of 1 month each. Phase I: observation after discontinuation of antiarrhythmic therapy. Phase II: arrhythmia analysis using the pacemaker memory after programming the lower rate to 55 ppm. The fallback function and histogram data were used to document the number and maximal duration of AA episodes as well as the total AA time in a month. Phase III: atrial overdrive. The mean ventricular heart rate was 65 ± 4 beats/min before atrial overdrive versus 75 ± 5 with atrial overdrive (P = 0.02). At the end of phase II, all patients presented with AA episodes (mean number per patient: 42 ± 78 in one month). In phase III (with atrial overdrive), 14 (64.6%) patients had no recorded AA (group A). In the other eight patients with persistent AA episodes in phase III (group B), there was a significant reduction in the number of AA episodes (90 ± 106 in phase II vs 38 ± 87 in phase III; P = 0.01), their total duration (166 ± 115 in phase II vs 92 ± 134 hours in phase HI; P = 0.03) and their maximal duration (121 ± 103 in phase II vs 85 ± 89 min; P = 0.04). Our short‐term data suggest tliat atrial overdrive prevents or reduces A A episodes and demonstrate the feasibility and need of long‐term studies to determine whether this benefit is sustained.
Steady‐State and Dynamic Behavior of Ventricular Repolarization and Refractoriness in the Dog: The Effect of Multiple Cycle Length Changes and d‐Sotalol Administration
Authors: LEERSSEN HENDRIK M. , VOS MARC A. , den BULK KAREL , van der ZANDE JOLANDA , MUIJTJENS ARNO M.M. , BEGEMANN MALCOLM J. , WELLENS HEIN J.J.
Published: July 2006

In anesthetized dogs with chronic, complete AV block we studied the characteristics of ventricular repolar‐ization and refractoriness. Therefore, we determined: (1) steady‐state values of ventricular effective refractory period (VERP), action potential duration (APD), and stimulus T interval (STI) before and after d‐sotalol treatment at various pacing cycle lengths (PCLs); and (2) the dynamics of VERP, APD, and STI before and after d‐sotalol treatment after the abrupt PCL decreases. VEHP, APD, and STI showed a normal frequency dependency. All three parameters increased significantly after d‐sotalol administration. During steady‐state and dynamic measurements, STI was always longer than APD and APD was always longer than VERP in an individual animal, irrespective of PCL and conditions. Standard deviations of steady‐state and dynamic values indicated a considerable interindividual variation. However, the dynamics of VERP, APD, and STI after an abrupt decrease in PCL were highly correlated (linear regression analysis: r2± 0.93). The best mathematical model to describe these dynamics was a bi‐exponential model (r2± 0.98) with a very short first and a much longer second time constant. We found that there was a very consistent relation between VERP, APD, and STI, not only during steady‐state but also in the dynamic situation after various abrupt PCL decreases. This relation does not change after the administration ofd‐so‐talol. Therefore, STI could be used to predict steady‐state and dynamic values of VERP and APD. Since STI can be made available online in implantable pacing systems this could lead to the development of new features in these devices.
Interactions between Pacemakers and Security Systems
Authors: WILKE ANDREAS , KRUSE TORSTEN , HESSE HARTMUT , FUNCK REINHARD , MAISCH BERNHARD
Published: July 2006

Electromagnetic fields arising from a variety of different sources have been shown to interfere with normal pacemaker function. This study evaluated the possible interactions between two modern security systems and different pacemaker types. Fifty–three patients (27 single chamber pacemakers, 25 dual chamber pacemakers) have been tested routinely for their pacemaker function. Thirty–eight patients presented with unipolar sensing and 15 with bipolar sensing. The patients were asked to walk through an installed security system, an antitheft device, and electromagnetic access device with different field strengths while a six–channel ECG monitored the patients. The pacemaker systems were first measured in their basic programmed modes, then the intervention frequency was changed to 100/min and, thereafter, the maximum sensitivity without T wave over– sensing was added. In the security system with the highest field strength (2,700 mA/m), a pacemaker malfunction could be observed in 13% of the monitored patients. In one case, a pacemaker (VVIR) switched to ventricular safety pacing (VOO mode). In the security system with the lower field strength (1,600 mA/m) we found a pacemaker malfunction in 4% of the tested patients. In the antitheft device (50 mA/m). in the electromagnetic access device (300 mA/m), and in pacemaker systems with bipolar sensing, none of these dysfunctions were observed. Phantom programming as described previously did not occur in any of the systems. Persons who are often in the vicinity of security systems should be equipped with a bipolar pacemaker system. Our findings indicate that patients with pacemakers should avoid contact with security systems.
The Mean Ventricular Fibrillation Cycle Length: A Potentially Useful Parameter for Programming Implantable Cardioverter Defibrillators
Authors: LI HUAGUI , EASLEY ARTHUR , WINDLE JOHN , SAMOIL DANIELA , HARRINGTON WILLIAM
Published: July 2006

In programming the implantable cardioverter defibrillator (ICD), the ventricular tachycardia (VT) detection cycle length (CL) is based on the CL of the documented tachycardia but the ventricular fibrillation (VF) detection CL is set arbitrarily. Appropriate programming of VF detection may not only reduce the incidence of inappropriate ICD shocks for non‐VF rhythms but can also avoid the fatal underdetection of VF. The mean VFCL may provide a useful parameter for optimal ICD programming for VF detection if it is reproducible. This study examined the intrapatient reproducibility and interpatient variation of the mean VFCL in 30 ICD patients (25 men and 5 women, mean age 63 ± 13 years). A total of 210 VF episodes (7 ± 4 per patient, range 3–17) induced by T‐wave shocks (166) or AC (44) at the ICD implant (30 patients) and the predischarge test (12 of 30 patients) were analyzed. The mean VFCL was calculated from the stored V‐V intervals in the ICDs. Although the mean VFCL varied significantly from 171 ± 6 to 263 ± 11 ms (P < 0.01) among different patients, it was reproducible among different VF episodes in an individual patient (maximal variation 4–50 ms, P > 0.05). The mean VFCL was not significantly different between patients with and without antiarrhythmic drugs (210 ± 32 vs 210 ± 23 ms, P > 0.05) and was correlated with the ventricular effective refractory period (r = 0.5, P < 0.05). The mean VFCL varies greatly among different patients but remains reproducible in an individual patient, suggesting that the mean VFCL may serve as a reference for ICD programming of VF detection.
Myocardial Lactate Extraction during Repeated Fibrillation/Defibrillation Episodes in Defibrillator Implantation Testing
Authors: WOLFHARD ULRICH F. , BRINKMANN MATTHIAS , SPLITTGERBER FRED H. , KNOCKS MICHAEL , SACK STEFAN , PIOTROWSKI JAROWIT A. , SCHIEFFER MICHAEL , CÜNNICKER MICHAEL
Published: July 2006

Intraoperative testing with several fibrillation/defibrillation episodes (FDEs) is routiinely performed during defibrillator implantation. Testing is considered safe even in patients with severe cardiac impairment, provided the recovery timespans and number of FDEs are adapted to the individual patient. Myocardial lactate extraction (MLE) was examined in two testing protocols. In 30 patients with coronary artery disease defibrillator implantations were performed under intravenous anesthesia. A percutaneous catheter was positioned into the coronary sinus(CS) under fluoroscopy. Two groups were randomly formed: group A (n = 20, mean number of FDEs: 4.2/patient) with 2 minutes waiting time between FDEs, and group B(n = 10. mean number of EDEs 4.1/ patients) with 10 minutes between FDEs. Defibrillation pulses were released 15 seconds after T wave shock induced fibrillation. To estimate MLE. arterial and CS blood samples were collected before and after each FDE. After the last FDE, samples were obtained after 5, 10, and up to 20 minutes. In group A, MLE fell from a baseline value of 29.6%± 3.6% before the FDEs to 7.8%± 5.4% immediately after the episodes. MLE recovered to 27.2%± 6.5% within 1 minute and overshot to 35.6%± 5.8% within 5 minutes. In group B, MLE decreased from 37.6%± 7.5% to 15.1%± 8.1% immediately after each EDE and rose to its original value (33.6 ± 7.8) within the 5‐minute recovery period. MLE decreased immediately after each FDE, and recovered within 1 minute even in poor left ventricular function. For full MLE recovery a 2‐minute wait between episodes is sufficient, if the total number of FDEs does not exceed four.
Cardioversion after Spontaneously Terminated Ventricular Tachycardia: What Is the Mechanism?
Authors: SCHWEITZER PAUL , HOFFMAN DARRYL
Published: July 2006

We report on an 84‐year‐old patient with an ICD who received a shock after a spontaneously terminated nonsustained ventricular tachyarrhythmia. We discuss the possible mechanisms of cardioversion after conversion of ventricular tachycardia and interventions that may prevent this type of inappropriate shock.
Recurrent Polymorphic Ventricular Tachycardia Complicating Radiofrequency Catheter Ablation of the Atrioventricular Junction
Authors: AZAR RABIH R. , LIPPMAN NEAL , KLUGER JEFFREY
Published: July 2006

Recurrent ventricular tachycardia and ventricular fibrillation were observed immediately after RF ablation of the AV junction in a 64‐year‐old man. This arrhythmia was preceded by ventricular bigeminy and a long‐short sequence. It was not associated with prolongation of the QT interval compared to baseline, and recurred 3 months later despite ventricular pacing at 90 beats/min. This is the first reported case of sustained ventricular arrhythmia complicating RF AV junction ablation despite rapid ventricular pacing, and recurring 3 months after discharge. It may explain the rare cases of sudden death complicating this procedure.
Familial Atrial Standstill with Coexistent Atrial Flutter
Authors: BALAJI SESHADRI , TILL JANICE , SHINEBOURNE ELLIOTT A.
Published: July 2006

A child with familial atrial staudstill and a ventricular pacemaker had syncope due to atrial flutter that was treated bv His‐bundle ablation. Bradycardia protection alone may be insufficient in patients with atrial standstill.
Measurement of Minute Ventilation with Different DDDR Pacemaker Electrode Configurations
Authors: BONNET JEAN‐LUC , RITTER PHILIPPE , PIOGER GUY ,   for the INVESTIGATORS OF A MULTICENTER STUDY EVALUATING THE CHORUS RM and OPUS RM PACEMAKERS
Published: July 2006

A rate responsive minute ventilation (VE) pacemaker was implanted in 49 patients (70.8 ± 40.0 years). A Chorus RM 7034 pacemaker was implanted in 43 patients and an Opus RM 4534 in six patients. Four sensor configurations were compared: atrial configuration (bipolar atrial lead) in 34 patients; ventricular configuration (bipolar ventricular lead) in 6 patients; unipolar configuration (double unipolar leads) in 6 patients; and floating configuration (VDD single‐pass lead) in 3 patients. The patients carried out 57 exercise tests in all with cardiopulmonary recording (CPX). Real VE and oxygen consumption (VO2) were recorded by the CPX, the VE measured by the sensor (VEsensor) was recorded in the pacemaker memory. The mean correlation between VE and VEsensor was 0.90 ± 0.08 (P < 0.001) and between VO2 and VEsensor was 0.86 ± 0.10 (P < 0.001). The mean correlation between VE and VEsensor by configuration type were as follows: atrial configuration = 0.89 ± 0.08; ventricular configuration = 0.95 ± 0.05; unipolar configuration = 0.87 ± 0.14; and floating configuration = 0.88 ± 0.05. In conclusion, VE may be reliably measured using different electrode configurations. A study conducted in a larger population should allow one to conclude that uniploar electrodes can be used in VDDR, AAIR, VVIR, or DDDR modes to measure VE.
Left Origin of the Atrial Esophageai Signal as Recorded in the Pacing Site
Authors: BAGLIANI GIUSEPPE , MENICONI LUIGI , RAGGI FRANGO , COREA LUIGI
Published: July 2006

Clear atrial depolarizations from inside the esophagus have always been recorded in electrocardiology, but their precise origin is still under discussion. Though atriol signals are recorded along most of the esophagus, pacing of the atria is possible only in a short tract, probably where the esophagus is in contact with the posterior left atrium wall. In order to ascertain which portion of atria gives rise to the esophageai atrial signal recorded in the atrial pacing segment, we examined 37 patients with normal P waves on the standard ECG by inserting esophageai and endocavitary catheters. The interval between the earliest start of the P wave and the bipolar atrial deflection, was measured both through the esophagus (PA‐Eso) and the Hisian region (PA‐His) (the latest depolarization of interatrial septum). The former was longer than the latter (P < 0.001) in 36 of 37 patients, showing that the esophagus recorded atrial signal, at the site of effective pacing, originates outside the interatrial septum. As the atrial depolarization recorded through the esophagus is significantly delayed compared with the Hisian region recording, a pure left origin of the esophageai signal can be hypothesized. This is supported by the well‐known delayed depolarization, during sinus rhythm, of the left atrium posterior wall compared with the right atrium and interatrial septum. Measuring the interval between the standard ECC P wave and atrial depolarization recorded through esophagus in the site of effective pacing, provides a reliable noninvasive estimate of interatrial time conduction.
Cardiac Output Is a Sensitive Indicator of Difference in Exercise Performance Between Single and Dual Sensor Pacemakers
Authors: LEUNG SUM‐KIN , LAU CHU‐PAK , TANG MAN‐OI
Published: July 2006

Although multisensor pacing may compensate the inadequacy of rate adaptation in a single sensor system, the clinical role of multisensor driven rate adaptive pacing remains unclear. We compared the performance between single sensor and dual sensor driven pacemakers using exercise cardiac output (CO) as a marker of cardiac performance. Eight patients with a mean age of 63 ± 3 years implanted with a dual sensor pacemaker driven by combined activity (ACT) and QT interval sensors were studied in the ACT‐, QT‐ only and the dual QT+ACT‐VVIR modes. Patients performed submaximal and maximal exercise tests with CO assessed by carbon dioxide rebreathing method. Comparing the HR response based on the change in metabolic workload, the ACT‐ VVIR “overpaced,” the QT'VVIR “underpaced,” and the QT+ACT‐VVlR achieved the best approximation to normal. The percentages of CO increase in ACT‐WIR and QT+ACT‐VVIR modes over resting CO were higher at 1 minute of exercise (295 ± 85% and 165 ± 49%, respectively) compared to the QT‐VVIR mode (81 ± 40%, P ≤ 0.05). During exercise, stroke volume cbanges from baseline were similar between ACT‐VVIR and QT + ACT‐VVIR modes, but a compensatory increase in stroke volume occurred in the QT‐VVIR mode during submaximal exercise (50 ± 11 mL vs 24 ± 17 mL in the QT+ACT‐VVlR and 14 ± 4 in ACT‐VVIR, P ≤ 0.003). There was no difference in the maximal exercise workload, exercise duration and CO at the submaximal and maximal exercise between the 3 sensor modes. Thus, exercise capacity is a poor indicator of sensor performance while CO measurement is a sensitive indicator of sensor mode differences especially at low workload exercise. The ACT‐ VVIR gave the fastest increase in CO at start of exercise at the expanse of overpacing, whereas the “under‐paced” QT‐VVIR compensated for the slower rate increase by utilizing contractility reserve during submaximal exercise. Dual sensor pacing, by achieving the best heart rate to workload relationship, provided a CO response without overpacing or using contractility reserve during exercise.
Infections with Nonthoracotomy Implantable Cardioverter Defibrillators: Can These Be Prevented?
Authors: SMITH PETER N. , VIDAILLET HUMBERTO J. , HAYES JOHN J. , WETHINGTON PATRICK J. , STAHL LYNNETT , HULL MICHAEL , BROSTE STEVEN K. ,   for the ENDOTAK LEAD CLINICAL INVESTIGATORS
Published: July 2006

Nonthoracotomy ICDs are believed to be the best therapeutic modality for treatment of life‐threatening ventricular arrhythmias. Little is known about the risk of infection with initial implantation of these devices. We studied the incidence, clinical characteristics, and risk factors associated with infections in 1,831 patients with nonthoracotomy ICD from the Endotak‐C nonthoracotomy lead registry of Cardiac Pacemakers, Inc. A transvenous lead was implanted in 950 patients (51.9%) and a combination transvenous plus subcutaneous patch was used in 881 patients (48.1%). Nine preselected data variables were studied, and all investigators identified as having patients with infections were personally contacted. Infections occurred in 22 (1.2%) of 1,831 patients receiving this nonthoracotomy ICD system. The mean time to infection was 5.7 ± 6.5 months (range 1–25 months). Staphylococci were isolated in 58% of patients with reported infection. The presence of a subcutaneous defibrillator patch system was associated with the development of infection. Six of 950 patients (0.63%) with a totally transvenous lead system developed infection versus 16 of 838 (1.9%) patients with a transvenous lead plus subcutaneous patch system configuration (P = 0.015, Chi‐square test), with an unadjusted estimated odds ratio of 3.06 (CI 1.19–7.86). The risk of infection encountered with the nonthoracotomy ICD is low, estimated from our data to be 1.2%. Placement of a subcutaneous defibrillator patch appears to be an independent risk factor for development of infection.
Frequency‐ and Time‐Domain Analysis of P Wave in Patients with Paroxysmal Atrial Fibrillation
Authors: HIRAKI TATSURO , IKEDA HISAO , OHGA MASANOBU , KUBARA TAKASHI HAMADA ICHIRO , YOSHIDA TERUHISA , AJISAKA HIDEHIKO , TANABE AKIHIRO , KANAHARA MASAAKI , IMAIZUMI TSUTOMU
Published: July 2006

We investigated the usefulness of the time‐ and frequency‐domain analysis of the P wave triggered signal‐averaged ECG (P‐SAECG) for detecting patients with paroxysmal atrial fibrillation (Paf). In previous studies, the usefulness of the time domain of the P‐SAECG to detect patients with Paf was described but that of the frequency domain is unknown. We analyzed the P‐SAECG in the time and frequency domain in 23 patients with Paf and 19 controls. The 32‐unipolar chest lead ECGs and the standard bipolar limb lead ECGs were obtained. The time‐domain analysis showed that the filtered P duration (fPd) was significantly longer (P < 0.01) in patients with Paf than controls: the predictive accuracy of Paf with fPd > 120 ms was 69%. The frequency domain analysis showed that the area ratio of power spectrum area of 0–20 Hz to 20–100 Hz (AR20) was significantly higher (P < 0.01) and the magnitude ratio at 30 Hz (%Mag.30) calculated by dividing the magnitude at 30 Hz by the maximal magnitude was significantly (P < 0.01) lower in patients with Paf than controls in the left lateral chest leads. The predictive accuracy of Paf with AR20 ≥ 1.5 and that with %Mag.30 < 40% was 83% and 73%, respectively. Our results indicate that the frequency‐domain analysis of P waves in lateral leads is useful as is the time‐domain analysis to detect patients with Paf. The AR20 ≥ 1.5 and %Mag.30 < 40% provides accurate predictability of Paf.
Absorbable Suture Technique: Solution to the Growth Problem in Pediatric Pacing with Endocardial Leads
Authors: STOJANOV PETAR , VELIMIROVIĆ DUŠAN , MD VLADIMIR HRNJAK , PAVLOVIĆ SINIŠA U. , ŽIVKOVIĆ MIRJANA , DJORDJEVIĆ ZORAN
Published: July 2006

Endocardial pacing system implantation has been performed in 15 children of mean age 37 months (ranging from 1 day to 89 months), Endocardial lead fixation was performed by means of slowly resorbable suture (Dexon) to allow spontaneous lead migration as the child grows. During a mean follow‐up period of 61 months (range 17–108 months), none of the patients needed reintervention for correcting the lead length to allow growth.
Radiofrequency Current Ablation of Porcine Right Atrium: Increased Lesion Size with Bipolar Two Catheter Technique Compared to Unipolar Application In Vitro and In Vivo
Authors: ANFINSEN OLE‐GUNNAR , KONGSGAARD ERIK , FOERSTER ARNOLD , AASS HALFDAN , AMLIE JAN P.
Published: July 2006

Interruption of atrial flutter and fibrillation by RF catheter ablation may be favored by large, elongated lesions. We administered RF current in unipolar and bipolar mode in porcine right atrium. Bipolar ablation was performed between the tip electrodes of two serially coupled catheters. With 4‐mm tip electrodes in vitro, lesion length increased from a mean (SD) of 7.9 (1.2) mm at 3 mm‐interelectrode distance (IED) to 13.3 (3.3) mm at 9‐mm IED, but decreased at 12‐mm IED due to nonconfluent lesions (P < 0.0001), With 4 mm distal electrodes and 8 mm IED, bipolar lesions were 65% longer than corresponding unipolar ablations. Switching to bipolar mode increased the lesion length more than increasing electrode tip length to 6 mm in unipolar mode. Power and temperature controlled ablation created equally sized lesions. Twelve anesthetized pigs were randomized to unipolar or two catheter bipolar temperature controlled ablation of the right atrial free wall. Bipolar ablation created confluent lesions with endocardial length × width of 13.5 (5.8) × 7.3 (3.7) mm, unipolar ablation 6.4 (2.8) × 4.6 (1.4) mm (P < 0.001 when comparing length and P = 0.013 for lesion width). The atrial lesions in both groups were transmural and extended into hilar lung lesions with maximal depth of 3.0 (1.1) and 2.6 (1.0) mm, respectively (P = 0.44). Five bipolarly and four unipolarly ablated pigs developed right diaphragmal paresis. We conclude that bipolar ablation may be preferable in situations where large, elongated lesions are favorable. The two catheter technique is feasible in porcine right atrium. Both bipolar and unipolar ablation of the porcine right atrial free wall may frequently be complicated by injury to the phrenic nerve and adjacent lung tissue.
Effect of the Superior Vena Cava Electrode Surface Area on Defibrillation Threshold in Different Lead Systems
Authors: TOMASSONI GERY , NEWBY KEITH , MOREDOCK LYNN , REMBERT JUDY , NATALE ANDREA
Published: July 2006

Little data is available comparing the efficacy of the Transvene, Endotak C 70 series, and the active CAN configuration on defibrillation success. In addition, the impact of the superior vena cava (SVC) electrode surface area and length on the active CAN system is unknown. Therefore, we compared the defibrillation efficacy of the Transvene and Endotak C 70 series lead systems with and without the active CAN in dogs. Defibrillation threshold (DFT) testing was randomly performed in 20 dogs. In protocol I [10 dogs), DFT energy was compared in three BV/SVC lead systems with an SVC electrode defibrillating surface area of 90 mm2 (Transvene‐90), 160 mni2 (Transvene‐160). 617 mm2 (En‐dotak), and an RV/CAN configuration. In protocol II (10 dogs), DFT comparison was performed in the Transvene‐90/CAN, Transvene‐160/CAN. Endotak/CAN, and RV/CAN configurations. In protocol I, in‐creasing the SVC surface area from 90 to 160 mm2 and from 160 to 617 mm2 significantly lowered DFT energy. The Endotak and the RV/CAN systems provided the lowest DET energy requirements. In protocol II, the Endotak/CAN system significantly lowered DFT energy compared to the other three lead configu‐rations. In both protocols, the impedance decreased as the SVC surface area increased from 90 to 160 mm2. However, no significant reduction in DFT impedance occurred as the SVC surface area increased from the Transvene‐160 to the Endotak lead. Increasing the SVC surface area from 90 to 617 mm2 in a two coil lead system lowered DFT energy to similar levels provided by the HV/CAN configuration. The addition of an SVC electrode with a surface area of 90 or 160 mm2 did not reduce DFT energy compared to the RV/CAN configuration. The Endotak/CAN system, however, provided the lowest DFT requirements.
Adverse Effects of Amiodarone
Authors: JAFARI‐FESHARAKI MAHTAB , SCHEINMAN MELVIN M.
Published: July 2006

Amiodarone was introduced 30 years ago as an antianginal agent and subsequently has been used as an antiarrhythmic agent. This drug was initially used for patients with malignant ventricular arrhythmias; however, currently it is being used broadly for rate and rhythm control in patients with atrial fibrillation. At first, amiodarone was primarily used by cardiologists and today it is used throughout the medical profession. Amiodarone therapy can potentially result in a wide range of adverse effects. The majority of these adverse effects are dose related and reversible. The following is a review of the adverse effects and drug interactions of amiodarone along with recommendations for identification and management of these adverse effects.
Frequency Dependent Shortening of Conduction Time through the Reentrant Pathway during Transient Entrainment of Ventricular Tachycardia
Authors: AIZAWA YOSHIFUSA , ITOH EIICHI , CHINUSHI MASAOMI , SHIBA MASAMI , UCHIYAMA HIROHIDE , SHIBATA AKIRA
Published: July 2006

In a patient with nonischemic ventricular tachycardia (VT), VT was entrained and the conduction time from the pacing site to the entrained local electrogram showed a rate dependent shortening and its degree affected by the pacing site. The QRS complex, which was entrained by the last pacing stimulus, was constant and identical to that of VT and no rate dependent facilitated conduction was observed when the heart was paced at similar paced cycle lengths during sinus rhythm. As the mechanism of the shortening of the conduction time through the reentrant circuit, a shift of the entrance seems most likely.
Recurrent Twiddler's Syndrome in a Nonthoracotomy ICD System Despite a Dacron Pouch
Authors: HIGGINS STEVEN L. , SUH BRIAN D. , STEIN JOSEPH B. , MEYER DAVID B. , JONS JOHNATHAN , WILLIS DICK
Published: July 2006

Twiddler's syndrome is a highly recognized yet rare complication of pacemaker and cardioverter defibrillator (ICD) implantation. We present a case in which persistent generator rotation resulted in lead dislodgment and inappropriate shocks in an initial ICD and recurrent lead fracture in a second ICD system. This case is unusual in that even with extensive surgical precautions including use of a Dacron pouch, generator rotation could not be prevented. Submuscular implantation and use of a smaller generator may prevent Twiddler's syndrome.
Transvenous Dual Chamber Pacing via a Unilateral Left Superior Vena Cava
Authors: ASHIDA YASUSHI , MORI TOHRU , KURODA HIROAKI , ISHIGURO SHINGO , KARA YOUICHI , TONOMOTO NAGAHISA
Published: July 2006

A 74‐year‐old woman with a unilateral left superior vena cava required dual chamber permanent pacing after a radical cardiac operation for an incomplete form of endocardial cushion defect. An active fixation ventricular lead was used to prevent the instability induced by the strange course of the electrode. For atrial pacing, a ventricular passive fixation lead was used. A transvenous dual chamber pacemaker was successfully inserted via a unilateral left superior vena cava.
Suppression of Erythromycin‐induced Early Afterdepolarizations and Torsade de Pointes Ventricular Tachycardia by Mexiletine
Authors: FAZEKAS TAMÁS , KRASSÓI IRÉN , LENGYEL CSABA , VARRÓ ANDRÁS , PAPP JULIUS GY
Published: July 2006

Erythromycin is a selective IKr‐blocking, action potential duration (APD)‐prolonging drug, which may induce early afterdepolarizations (EADs) and torsade de pointes ventricular tachycardia. The successful termination of an erythromycin‐induced clinical torsades de pointes by the authors with mexiletine prompted them to investigate in vitro whether erythromycin is able to induce EADs in Purkinje fibers and, if so, whether EADs are suppressible or not by mexiletine. Electrically stimulated canine Purkinje fibers (n=9) were superfused with erythromycin (200 mg/l) and action potentials were recorded by an intracellular microelectrode technique. Erythromycin induced a pronounced prolongation of APD and the appearance of EADs in all Purkinje preparations (9/9). After the addition of mexiletine (10 mM), a marked shortening of APD and the disappearance of EADs (7/9) were observed. Mexiletine, an inhibitor of the tetrodotoxin‐sensitive window Na+‐current, may prevent IKr‐blocking drug‐induced torsade de pointes ventricular tachycardia by abolishing APD prolongation and EADs.
Neutrophil‐Derived Oxidative Stress After Myocardial Ischemia Induced by Incremental Atrial Pacing
Authors: GIANNITSIS EVANGELOS , TETTENBORN IVO , WIEGAND UWE , POTRATZ JUERGEN , SHEIKHZADEH ABDOLHAMID , STIERLE ULRICH
Published: July 2006

We studied the effect of atrial pacing‐induced myocardial ischemia on the generation of oxygen free radicals (OFR) in 8 patients with verified coronary artery disease (CAD) and in a control group of 4 patients without coronary atherosclerosis. Myocardial ischemia was measured metabolically by simultaneous lactate sampling from coronary sinus (CS) and arterial blood. Generation of OFR from purified viable polymorphonuclear neutrophils (PMN) was assessed by means of the chemiluminescence (CL) method. At peak pacing, 7 of 8 patients with CAD exhibited transient myocardial ischemia (mean lactate extraction ratio at rest: 23.6 ± 7.7 vs 5.21 ± 5.1 % at peak pacing, p= 0.012). In these patients, unstimulated PMN harvested from the CS depicted a significant increase of luminol‐enhanced CL (from 1.06 ± 0.54 to 2.15 ± 1.28 cpm x 105, p= 0.012) after atrial pacing. There was no additional effect from further ex vivo stimulation with phorbol myristate acetate.

This finding underscores the role of myocardial ischemia as a potent endogenous activator of PMN function and may have implications in the pathogenesis and progression of atherosclerosis.
Histological Examination of the Topography of the Atrioventricular Nodal Artery within the Triangle of Koch
Authors: KOZLOWSKI DARIUSZ , KOZLUK EDWARD , ADAMOWICZ MONIKA , GRZYBIAK MAREK , WALCZAK FRANCISZEK , WALCZAK EWA
Published: July 2006

The treatment of choice in patients with drug‐resistant atrioventricular nodal reentry tachycardia is radiofrequency fast or slow pathway ablation. Ablation of the reentrant circuit in the region of the His bundle, when approached from the anterior‐superior region (fast pathway), can result in complete AV block. This is less likely if the posterior‐inferior (in the region of coronary sinus ostium) approach is used (slow pathway ablation). The possibility that radiofrequency energy may damage the vascular sjdpply to the AV node must be considered. In order to confirm this hypothesis observation was conducted on the autopsy material of 50 human hearts (20F, 30M) from 18 to 81 years of age. Specimens were taken containing the triangle of Koch (the apex‐ right fibrous trigone, the base‐ coronary sinus ostium). These histological blocks were sectioned in the frontal plane and stained using Masson's method. Koch's triangle was divided in the sagittal plane into 3 parts: inferior (between the base and the attachment of the tricuspid valve), central (between the base and the apex of the right fibrous trigone) and superior (between this trigone and the tendon of Todaro). It was observed that the AVN artery at the coronary sinus ostium level (the base of the triangle of Koch) was positioned in 68% in the central and in 32% in the inferior part of Koch's triangle. The AVN artery in the central part was removed from the endocardium 1mm (18%), 2mm (42%), 3mm (22%), 4mm (18%). In the inferior part imm (26%), 2mm (37%), 3mm (37%). No statistically significant relationship was observed between those groups. Conclusions: 1) in 20% of examined hearts the AVN artery lay just beneath the endocardium near the coronary sinus ostium 2) there is a risk of the AVN artery coagulation during radiofrequency ablation m the slow pathway region.
New Insight into Repolarization Abnormalities in Patients with Congenital Long QT Syndrome: the Increased Transmural Dispersion of Repoiarization
Authors: LUBINSKI ANDRZEJ , LEWICKA‐NOWAK EWA , KEMPA MACIEJ , BACZYNSKA ANNA M. , ROMANOWSKA ILONA , SWIATECKA GRAZYNA
Published: July 2006

There is evidence from experimental studies that the time interval from the peak to the end of T‐wave reflects the transmural dispersion in repolarization (electrical gradient) between myocardial “layers” (epicardial, M‐cells, endocardial). Since Congenital Long QT Syndrome (LQTS) is considered to be classical disease or repolarisation abnormalities, we performed the present study to assess the transmtiral dispersion of repolarization in LQTS patients. The study group consisted of 17 patients: 7 LQTS pts and 10 pts from the control group. In each patient the 24‐hour ECG recording was performed on magnetic tape. The interval from the peak to the end of the T‐wave (TpTo) was automatically measured by Holter system during every hour as a measure of transmural dispersion of repolarisation. Thereafter the mean TpTo from 24‐hours was calculated. In addition the spatial QT dispersion was measured from 12 lead ECG and 3 channel Holter tape as a difference between the shortest and the longest QT interval between leads. The values were compared between groups using the Anova test.

TpTo was 79,6±9,6 ms (72–92 ms) in LQTS group and 62,4±7,5 ms (51–70) in the control group (p< 0.001). In LQTS group TpTo was significantly longer at night hours 72,5±2 when compared to day hours 87,4±8 (p<0.01). The spatial QT dispersion was significantly higher in LQTS patients when compared to control, both in 12‐lead standard and Holter ECG.

Congenital long QT syndrome is associated with increase in both transmural and spatial dispersion of repolarization. The extent of prolongation of the terminal portion of QT in patients with congenital long QT syndrome is greater at night sleep hours compared to daily activity.
Does the Change of the Polarity of Electrodes Influence the Results of Transoesophageal Bidirectional DC Cardioversion?
Authors: POLESZAK KRZYSZTOF , KUTARSKI ANDRZEJ , KOZIARA DARIUSZ , BASZAK JACEK , OLESZCZAK KRZYSZTOF
Published: July 2006

The aim of the study was to compare the bidirectional transoesophageal DC cardioversion (BOC) with unidirectional transoesophageal DC cardioversion (UOC) and to evaluate, if the reversion of the polarity of electrodes alters the effectiveness and the amount of energy during BOC. UOC was attempted in 300 patients (pts) with atrial fibrillation (AF) and BOC in 241 pts with AF. In UOC mode shocks were delivered between the 4‐ring oesophageal electrode (cathode) and the chest pad (anode) positioned in the precordial region. In BOC shocks were delivered between the same oesophageal electrode and two chest pads joined with each other, positioned on both sides of the sternum. First 147 pts were cardioverted with the oesophageal electrode as a cathode, next 94 with an anode in oesophageal position. The effectiveness of both modes (UOC and BOC) was very high, however in pts with chronic AF success rate was better in BOC approach (82% vs 100%). BOC, compared with UOC, allowed to decrease the threshold defrbrillation signifrcantly: in pts with recent onset of AF from 61,5 J to 33,3 J and in pts with chronic AF from 99,8 J to 75,2 J. In pts with long standing AF the reduction of the defrbrillation threshold was statistically not significant (from 68,6 J to 50,6 J). The effectiveness of BOC was also very high independently of the polarity of electrodes. The change of the polarity did not affect the minimal and total successful energy of shocks, too. In pts with oesophageal electrode as a cathode defibrillation threshold was 48,4 J and in pts with the anodal electrode 43,7 J. In conclusions we found BOC as a very effective method in pts with AF. Defibrillation threshold in BOC is lower than in UOC and the polarity of electrodes does not influence the success rate and successful energy.
A Relationship Between Fluctuations in Heart Rate and The Duration of Subsequent Episodes of Atrial Fibrillation
Authors: HNATKOVA KATERINA , WAKTARE JOHAN EP , SOPHER S MARK , MURGATROYD FRANCIS D , BAIYAN XIE , CAMM A JOHN , MALIK MAREK
Published: July 2006

A relationship between autonomic tone and the onset of paroxysmal atrial fibrillation in some patients is recognised Episodes of PAF may vary enormously in duration, however, from a few beats to many hours. Whether autonomic tone influences the duration of ihe episodes has been less well investigated.

From a database of Holter recording taken from patients with symptomatic PAF, we identified all episodes of at least 30 seconds duration which were preceded by noise free sinus rhythm. This study examined the heart rate prior to AF onset, the change in heart rate over the final minute of sinus rhythm and the time of AF onset, and compared the data from those episodes of AF of more than 5 minutes duration to the shorter ones. Heart rate was slower before long episodes of AF, but this was found to predominantly represent data from separate recordings. A highly significant rise in heart rate was detected prior to long AF episodes compared to shorter ones. Daytime AF episodes were slightly longer than nocturnal ones.

The most important finding was that longer AF episodes were typified by a heart rate acceleration. This suggests that, regardless of underlying aetiology, and increase in sympathetic tone may be important in the sustenance of episodes of PAF.
Multiparametric Analysis of Heart Rate Variability Used for Risk Stratification Among Survivors of Acute Myocardial Infarction
Authors: VOSS ANDREAS , HNATKOVA KATERINA , WESSEL NIELS , KURTHS JUERGEN , SANDER ANDRE , SCHIRDEWAN ALEXANDER , CAMM A JOHN , MALIK MAREK
Published: July 2006

A multiparametric heart rate variability analysis was performed to prove if combined heart rate variability (HRV) measures of different domains improve the result of risk stratification in patients after myocardial infarction. In this study, standard time domain, frequency domain and non‐linear dynamics measures of HRV assessment were applied to 572 survivors of acute myocardial infarction. Three parameter sets each consisting of 4 parameters were applied and compared with the standard measurement of global heart rate variability HRVi. Discriminant analysis technique and t‐test were performed to separate the high risk groups from the survivors. The predictive value of this approach was evaluated with receiver operator (ROC) and positive predictive accuracy (PPA) curves. Results ‐ The discriminant analysis shows a separation of patients suffered by all cause mortality in 80% (best single parameter 74%) and sudden arrhythmic death in 86% (73%). All parameters of set I show a high significant difference (p<0.001) between survivors and non‐survivors based on two‐tailed t‐test. The specificity level of the multivariate parameter sets is at the 70% sensitivity level (ROC) about 85–90%, whereas HRVi shows maximum levels of 70%. The PPA in the all cause mortality group is at the 70% sensitivity level twice as high as the univarihate HRV measure and increases to more than fourfold as high within the VT/VF group. In conclusion, in this population, the multiparametric approach with the combination of four parameters from all domains especially from NLD seems to be a better predictor of high arrhythmia risk than the standard measurement of global heart rate variability.
Tilt Training: A New Treatment for Recurrent Neurocardiogenic Syncope and Severe Orthostatic Intolerance
Authors: ECTOR HUGO , REYBROUCK TONY , HEIDBÜCHEL HEIN , GEWILLIG MARC , VAN DE WERF FRANS
Published: July 2006

Medical treatment of neurocardiogenic syncope is insufficient in many cases. We have observed a therapeutic effect of repeated head‐up till testing. Therefore, we have started a program of tilt training for heavily symptomatic patients. After hospital admission, they were tilted daily (60° inclination) until syncope, or until a duration of 45–90 minutes (90 sessions in 13 patients). The mean tilt tolerance, at the first diagnostic head‐up tilt table test, was 22.3 minutes (st. dev. 10.9). Before hospital discharge, 12/13 patients could sustain the full duration of tilt table testing without any symptom. In one patient syncope persisted. The patients were instructed to continue a program of daily tilt training at home, by standing against a wall for 30 minutes, one or two times per day. This resulted in a complete disappearance of syncope in all 13 patients.

Orthostatic intolerance and the excessive autonomic reflex activity of neurocardiogenic syncope can be remedied by a program of continued tilt training, without the administration of drugs.
Risk Stratification for Recurrent Tachyarrhythmias in Patients with Paroxysmal Atrial Fibrillation and Flutter: Role of Signal Averaged Electrocardiogram and Echocardiography
Authors: TURITTO GIOIA , BANDARIZADEH BABAK , SALCICCIOLI LOUIS , ABORDO MELECIO G. , PIZZARELLI MASSIMILIANO , EL‐SHERIF NABIL
Published: July 2006

The value of signal‐averaged P‐wave electrocardiogram and echocardiography for predicting recurrent atrial tachyarrhythmias was prospectively investigated in 60 patients presenting with paroxysmal atrial fibrillation or flutter. All patients were followed up for 1 year after restoration of sinus rhythm. A stepwise discriminant function analysis was used to identify variables predicting recurrent atrial tachyarrhythmias. Analyzed variables included signal‐averaged P‐wave duration in 3 bipolar orthogonal leads (X,Y,Z) and their vector magnitude, as well as left and right atrial dimensions and volumes. During follow‐up, 25 patients had recurrent atrial tachyarrhythmias, while 35 did not. Using discriminant function analysis, the left atrial antero‐superior dimension was found to be the only variable predicting the recurrence of atrial tachyarrhythmias (p<0.0038) and was able to correctly classify 65% of the study patients. It was concluded that, in patients with paroxysmal atrial fibrillation or flutter, the traditionally used determination of left atrial dimension was the variable most closely associated with a high risk for recurrent tachyarrhythmias. The signal‐averaged P‐wave duration did not improve tachyarrhythmia prediction.