bluuebunny/crossref_metadata_2025 huggingface dataset:
Gross and Microscopic Changes Associated with a Nonthoracotomy Implantable Cardioverter Defibrillator
Authors: EPSTEIN ANDREW E. , ANDERSON PETER G. , KAY G. NEAL , DAILEY SHARON M. , PLUMB VANCE J. , SHEPARD RICHARD B.
Published: July 2006

The pathology associated with an invesrigational transvenous defibriliating and sensing lead is described. The lead system had delivered a total of 865 J from the time of implantation to the time of patient death from a noncardiac cause 7 months after implantation and 1 month after his last defibrillator shock. There was mild, superficial fibrous thickening on the endothelial surface of the superior vena cava adjacent to the proximal spring electrode, which did not extend into the vessel wall. The distal portion of endocardial lead was embedded in the interventricular septum near the apex of the right ventricle, surrounded by fibrous thickening, and partially covered by endocardial tissue. Microscopically, there was a thick bed of fibrous connective tissue surrounding the lead with extensive interstitial fibrous connective tissue radiating into the adjacent myocardium. Since this pattern is different from the more generalized fibrotic scarring produced by myocardial infarction, we speculate that the mechanism for the observed interstitial fibrosis is replacement fibrosis following acute myocyte injury that resulted from prior defibrillator shocks and possibly from the trauma produced by the lead compressing adjacent myocardium during systole. Potential effects on device efficacy of these fibrotic changes at the bioelectric interface include their representing a new arrhythmia substrate, the possibility that fibrosis could increase both defibrillation and pacing thresholds, and that the inflammatory reaction may cause deterioration of intracardiac electrograms and interfere with sensing and tachycardia recognition.
Hemodynamic Effects of Different Temporary Pacing Modes for the Management of Bradycardias Complicating Acute Myocardial Infarction
Authors: MURPHY PHILIP , MORTON PATRICIA , MURTAGH J. GERARD , SCOTT MICHAEL , O'KEEFFE D. BARRY
Published: July 2006

Twelve patients requiring temporary pacing following acute myocardial infarction (AMI) (10 heart block, 2 functional bradycardia) had hemodynamic measurements taken with ventricular demand pacing at 80 ppm (VVI80), ventricular demand pacing at the atrial rate (VVIa), physiological pacing (DDD), and spontaneous (intrinsic) rhythm. VVI80 mode did not improve any hemodynamic parameter compared with spontaneous rhythm. VVIa mode improved diasfolic and mean arterial pressures only. DDD mode improved most hemodynamic parameters compared with spontaneous rhythm (cardiac output by 29% [P < 0.0001]; blood pressure: diastolic by 24% [P < 0.01], systolic by 19% [P < 0.01], mean by 21% (P < 0.005]; pulmonary wedge pressure by 10% [P = 0.057] and right atrial pressure by 24% [P < 0.005]) and also significantly improved some parameters compared with VVIa (cardiac output by 20% [P < 0.001], systolic blood pressure by 11% [P < 0.01] and right atrial pressure by 15% [P < 0.01]). Physiological pacing is hemodynamicaily superior both to ventricular pacing and spontaneous rhythm for patients requiring temporary pacing following AMI. Ventricular pacing at 80 ppm has little hemodynamic advantage over spontaneous rhythm.
Late Development of Conduction Block Over the Mahaim Fibers After Electrical Atrioventricular Junction Ablation for Mahaim Fiber Tachycardia
Authors: KRITHARIDES L. , VOHRA J.
Published: July 2006

A patient suffering from so called “Mahaim fiber” tachycardia is presented who developed complete heart block over Mahaim fibers after 18 months of AV junction ablation. Antegrade conduction along the Mahaim fiber ivas intact immediately after the procedure. This finding has not been previously described and suggests that permanent pacemaker implantation is mandatory in such patients.
Longevity in Patients With High Degree Atrioventricular Block Paced in the Atrial Synchronous or the Fixed Rate Ventricular Inhibited Mode
Authors: LINDE‐EDELSTAM CECILIA , GULLBERG BO , NORLANDER ROLF , PEHRSSON S. KENNETH , ROSENQVIST MÅRTEN , RYDÉN LÅRS
Published: July 2006

Survival in patients paced for high degree AV block has been demonstrated to be influenced by underlying cardiac disease in particular congestive heart failure. One previous study has suggested that dual chamber pacing may improve the vital prognosis for such patients. To investigate this, 74 patients treated with rate adaptive atrial synchronous (VDD) and 74 patients treated with VVI pacemakers for high degree AV block, were retrospectively studied for a mean of 5.4 years by life‐table analysis. The two groups had an equal distribution of age, sex, date of pacemaker implantation, and concomitant cardiovascular diseases. Total mortality and estimated survival did not differ between the two groups. The estimated survival in the VDD group at 1, 3, and 5 years for patients without and with congestive heart failure was 94%, 86% and 78%, and 92%, 83% and 72%, respectively. In the VVI group the corresponding values were 95%, 90%, and 83% for patients without congestive heart failure and 82%, 64%, and 47% for those with congestive heart failure (P = 0.008). Compared to the expected survival rate of the general Swedish population, only the VVI group with congestive heart failure, had an excess mortality (P = 0.007). Patients with high degree AV block have a fairly normal vital prognosis irrespective of pacing mode. The prognosis for patients with congestive heart failure was negatively affected by VVI pacing. Thus, for patients with congestive heart failure the choice of pacing mode is of vital importance, whereas for patients without congestive heart failure, other factors such as feeling of well‐being and exercise capacity should decide the final choice of pacing mode.
Effect of Bilateral Stellectomy on Electrical Instability of the Atrium in the Dog with Hypokalemia
Authors: YANO KATSUSUKE , MITSUOKA TAKAO , HIRATA TETSUYA , HAND OSAMU , HIRATA MASANOBU , MATSUMOTO YORIAKI
Published: July 2006

To investigate the effect of sympathetic nerve activity on electrical instability of the atrium in the presence of hypokalemia, open chest elecfrophysiological study was performed before and after bilateral stellectomy (BS) in 15 dogs with hypokalemia (hypokalemia group) and in 15 dogs with normo‐kalemia (control group). Hypokalemia was created by infusion of 5.0 g/kg of polystyrene sulfonic acid calcium into the colon. Serum level of potassium was significantly lower in the hypokalemia group (2.94 ± 0.52 mEq/L) than in the control group (4.86 ± 0.51 mEq/L, P < 0.01) before BS. There was no significant change in serum level of potassium in the two groups after BS. Incidence of electrically induced atrial fibrillation (AF) was significantly higher in the hypokalemia group (80%) than in the control group (13%, P < 0.001) before BS. It was significantly reduced in (he hypokalemia group (40%, P < 0,05), but not in the control group (6%) after BS. Dispersion of effective refractory period of the atrium (AEHP) was significantly greater in the hypokalemia group (26.1 ± 2.8 msec) than in the control group (22.0 ± 3.3 msec, P < 0.005) before BS. ft was significantly decreased to 23.1 ± 3.2 msec in the hypokalemia group (P < 0.001) and to 20.6 ± 2.5 msec in the control group (P < 0.01) after BS. Maximum conduction delay in the atrium (MaxCD) was 36.1 ± 3.5 msec before and 36.2 ± 4.1 msec after BS in the hypokalemia group and 31.1 ± 4.2 msec before and 32.3 ± 4.9 msec after BS in the control group. There was a significant difference in MaxCD betiveen the two groups before BS. Atrial fibrillation threshold (AFT) was significantly lower in the hypokalemia group (3.9 ± 0.7 mA) than in the control group (33.8 ± 3.1 mA, P < 0.001) before BS. It was significantly increased both in the hypokalemia group (6.5 ± 1.3 mA, P < 0.001) and in the control group (15.0 ± 2.7 mA, P < 0.005) after BS. It is concluded that sympathetic nerve activity may play some role in the increase in electrical instability of the atrium in the presence of hypokalemia.
Results of Electrophysiological Testing and Long‐Term Follow‐Up in Patients Sustaining Cardiac Arrest Only While Receiving Type IA Antiarrhythmic Agents
Authors: HOOK BRUCE G. , ROSENTHAL MARK E. , MARCHLINSKI FRANCIS E. , BUXTON ALFRED E. , JOSEPHSON MARK E.
Published: July 2006

Therapeutic management of patients sustaining a cardiac arrest while receiving antiarrhythmic agents can be difficult since the role of the drug in possibly facilitating the arrhythmia is often difficult to define. To determine if the response to programmed stimulation could give insight into which patients may have experienced a drug‐induced cardiac arrest, we studied 29 patients (61 ± 9 years) with no prior history of sustained ventricular tachyarrhythmias (VT) who suffered a cardiac arrest only while receiving type la antiarrhythmic agents. Patients with documented myocardial infarction, acute ischemia, electrolyte abnormalities, or torsade de pointes were excluded from the study. Twenty‐four patients had coronary artery disease with prior myocardial infarction (ejection fraction 28%± 9%) and five patients had idiopathic dilated cardiomyop‐athy (ejection fraction 31%± 6%). During baseline electrophysiological testing, 19 patients (66%) had inducible sustained ventricular arrhythmias: uniform VT, n = 14 (group I), polymorphic VT or ventricular fibrillation, n = 5 (group II). Ten patients (group III) had no inducible sustained ventricular arrhythmias. To determine if rechallenge with a type la agent could facilitate induction of a sustained ventricular arrhythmia in group III, eight patients underwent ten electrophysiological studies during therapy with either procainamide or quinidine. Only two patients developed sustained VT in response to programmed stimulation. Patients in groups I and II received therapy guided by electrophysiological testing, including antiarrhythmic agents alone (n = 8), subendocardial resection (n = 4), or an implantable cardioverter defibrillator (n = 7). Patients in group III received antiarrhythmic agents empirically (n = 3), or for treatment of atrial tachyarrhythmias (n = 2) or nonsustained VT (n = 1). In addition, four patients in group III received an implantable cardioverter defibrillator. During a mean follow‐up of 28 ± 27 months (range: 1 day‐84 months) 13 patients died suddenly or received a defibrillator shock preceded by syncope or presyncope: group I: n = 5; group II: n = 2; group III: n = 6. In conclusion: (1) most patients sustaining a cardiac arrest only in the presence of type la antiarrhythmic agents have inducible sustained VT in the absence of antiarrhythmic agents, and (2) the risk of recurrent VT persists in patients without inducible sustained arrhythmias in the drug‐free state, regardless of whether they manifest inducible arrhythmias after rechallenge with a type la agent.
Clinical Experience with an Activity Sensing DDDR Pacemaker Using an Accelerometer Sensor
Authors: LAU CHU‐PAK , TAI YAU‐TING , FONG PING‐CHING , LI JOHN P.‐S. , LEUNG SUM‐KIN , CHUNG FELSA L.‐W. , SONG STELLA
Published: July 2006

The rate adaptive characteristics and pacemaker mediated tachycardia protection algorithm of an accelerometer based DDDR pacemaker were evaluated in 11 patients with bradycardia (seven atrioventricular block, four sick sinus syndrome). Rate adaptive programming was effected by collecting the acceleration level during a 3‐minute moderate exercise (“tailoring” of sensor). In comparison with an externally attached piezoelectric sensor, the accelerometer sensor showed lower rate changes during external tapping of the pacemaker (16 ± 3 vs 29 ± 4 ppm, P < 0.02) and applied direct pressure (1 ± 1 vs 40 ± 3 beats/min, P < 0.001) on the pacemaker. At nominal setting, the accelerometer sensor showed improved rate stability and higher rate response to jogging and standing, although responses to other daily activities and treadmill exercise were similar. Apart from changing the rate responsive slope, rate response could be improved by repeat “tailoring” of the sensor at a lower exercise level, resulting in better overall rate response characteristics. The ability of the rate monitoring software to collect acceleration levels for an activity and profile the projected rate response at different rate responsive settings allowed programming to be effected with the minimum amount of exercise testing. The pacemaker also discriminated atrial tachyarrhythmias from normal sinus response using the sensor to judge the appropriateness of the atrial rate, which correctly identified and prevented rapid ventricular tracking in two patients during atrial flutter/fibrillation.
Effect on Ventricular Performance of Direct Current Electrical Shock for Catheter Ablation of the Atrioventricular Junction
Authors: AURICCHIO ANGELO , KLEIN HELMUT , TRAPPE HANS‐JOACHIM , SALO RODNEY
Published: July 2006

In ten patients undergoing catheter ablation of the atrioventric‐ular junction (CAVJ) because of therapy refractoriness of supraventricular arrhythmias, the effect of repeated high energy direct current (DC) shock on left ventricular function has been investigated. End‐systolic pressure‐volume relation (ESPVR) and the positive first derivative of ventricular pressure (dP/ dt) have been used as indices of left ventricular systolic function, while the time constant of isovolumic pressure decay, the diastolic stiffness, and the negative dP/dt represented the diastolic function parameters, respectively. Each patient received at least two and no more than three DC shocks for successful CAVJ, with an energy of 360 joules. Significant acute reduction of both systolic and diastolic function was noted after each DC shock, with a slow partial recovery of both phases. The recovery process involved the systolic phase earlier and more completely than the diastolic one. The alterations observed could not be predicted from preablation values, but were significantly related to cumulative energy dose index for body weight. In conclusion, repeated high energy DC shocks acutely, but reversibly, impair left ventricular function; in addition, the ventricular function reduction is primarily related to the total ablation energy indexed for body weight.
Adapter Failure as a Cause of Pacemaker Malfunction
Authors: van GELDER BERRY M. , BRACKE FRANK A.L.E. , El GAMAL MAMDOUH I.H.
Published: July 2006

Two patients who had recently undergone pulse generator replacement in which an adapter had been used to connect a preexisting lead to a VSi and ISi 3.2‐mm connecter presented with noncaplure. The adapter set‐screw was found to be protruding from the insulation sleeve to short‐circuit with the pulse generatorcan. During episodes of noncapture the telemetered impedance was < 100 ohms.
A New Stimulation Protocol for Cardiac Assist Using the Latissimus Dorsi Muscle
Authors: LUCAS CAROLINE M.H.B. , DUBELAAR MARIE‐LOUISE , VAN der VEEN FREDERIK H. , KLOOSTERMAN‐CASTRO‐RAVELO ELISA , HAVENITH MICHAEL , HABETS JO , van der NAGEL THEO , PENN OLAF C. , WELLENS HEIN J.
Published: July 2006

When treating severe cardiac failure with dynamic cordiomyoplasty, knowledge about the optimal way of stimulating the latissimus dorsi (LDJ muscie is of obvious importance. We evaluated a new stimulation protocol in/our goats using in situ electrical stimulation of the left LD muscle. Stimulation was started using a burst of two pulses with an interpulse interval of 100 msec for 50 bursts/min. The number of pulses was increased every 2 weeks concomitant with a decrease in interpulse interval. This resulted after 12 weeks in 60 bursts/min using bursts of six pulses with an interpulse interval of 20 msec after 12 weeks. Force measurements, which were done every 2 weeks, shoived an early decrease in contraction and relaxation speed as reflected in the ripple (= interstimulus amplitude/peak force amplitude measured at 10 HzJ. Fatigue resistance increased significantly within 4 weeks of conditioning as indicated by preservation of force, positive dF/dt, and negative dF/dt. Full preservation of these variables was seen even during a 1‐hour fatigue test at the end of the conditioning period. Skeletal muscle enzyme activity as an indicator of muscle domage showed a significont rise in creatine kinase enzyme activity only on the first day following the start of LD stimulation. LD muscle biopsies revealed almost complete transformation to type I muscle fibers with a significant increase in capillary/fiber ratio when compared to the nonsfimulated LD muscle. However, some biopsies, in particular near the electrodes, did show some signs of skeletal muscle damage. Contraction characteristics of the fully transformed LD muscles were tested by increasing the number of bursts of six pulses from 50/min to 100/min. Interpulse intervals of 20 and 33 msec were used. These tests revealed thaf maximal force, positive dF/dt, and negative dF/dt was reached with 50 bursts/min using a six pulse burst with interpulse intervals of 20 msec.
Intravenous Adenosine Can Reveal Accessory Pathways Not Revealed By Routine Electrophysiological Testing
Authors: MORGAN‐HUGHES NICHOLAS J. , GRIFFITH MIGHAEL J. , McGOMB JANET M.
Published: July 2006

This article describes a patient in whom the administration of adenosine revealed the presence of an accessory pathway when electrophysiological testing had failed to do so.
Development of an Aortic Valve Mass After Radiofrequency Catheter Ablation
Authors: RAITT MERRITT H. , SCHWAEGLER BECKY , PEARLMAN ALAN S. , POOLE JEANNE E. , BARDY GUST H. , LEE DOLACK G. , KUDENCHUK PETER J.
Published: July 2006

A 49‐year‐old woman underwenl a successful radiofrequency catheter ablation of a left‐sided accessory pathway using a retrograde approach across the aortic valve. Routine echocardiogruphy performed 20 hours after the procedure revealed a new aortic valve mass. Five blood cultures were negative. An echocardiogram after 2 days of heparin therapy showed complete resolution of the mass. There was no clinical evidence of embolization. Echocardiography may need to be performed routinely after catheter ablations performed retrograde across the aortic valve so that this potentially devastating complication can be diagnosed and treated early in its course.
Coronary Artery Bypass in Patients with Previously Placed Implantable Defibrillators
Authors: BLAKEMAN BRADFORD P. , WILBER DAVID , OLSHANSKY BRIAN , KALL JOHN
Published: July 2006

Four patients with previously placed implantable defibrillators required coronary revascularization several years after the original device was inserted. Three patients had a conventional system of epicardial patches and leads, and one patient had a nonthoracotomy system placed, All four patients were successfully revascularized without evidence of perioperative infarction or significant morbidity. The patient with the nonthoracotomy device did require manipulation of the endocardial lead at a separate setting. This limited experience suggests that patients needing revascularization after placement of an implantable defibrillator can be successfully by passed.
Cardioversion, Defibrillation, and Overdrive Pacing of Ventricular Arrhythmias: The Effect of Moricizine in Dogs with Sustained Monomorphic Ventricular Tachycardia
Authors: AVITALL BOAZ , HARE JOHN , ZANDER GARY , LESSILA CYNTHIA , DHALA ANWER , DESHPANDE SANJAY , JAZAYERI MOHAMMAD , SRA JASBIR , AKHTAR MASOOD
Published: July 2006

The purpose of this investigation is to define whether the antiarrhythmic drug moricizine has beneficial or adverse effects on currently used antitachycardia and antifibrillatory devices. These studies were performed in a dog model of sustained monomorphic ventricular tachycardia (VT). In 11 dogs, the left anterior descending artery and all surrounding epicardial collateral feeder vessels were ligated. Defibrillator patches were implanted and the dogs were allowed to recover. After a 7‐day recovery period, effective refractory period (ERP), end diastolic threshold (EDT), VT induction, and VT and ventricular fibrillation (VF) termination data were collected before and after moricizine infusion (2 mg/kg). In this experimental model, moricizine caused the folIowing electrophysiological changes: a prolongation of the ERP from 173 ± 14 to 182 ± 15 fP < 0.02) with no significant effect on the EDT for pacing; a prolongation of the VT cycle length from 175 ± 18 to 201 ± 23 msec (P < 0.003); an increased cycle length required for overdrive pacing from 136 ± 20 to 157 ± 22 msec (P < 0.01); no effect on the energy required to cardiovert VT; an increase in the defibrillation threshold from 7.5 ±4 to 9.4 ± 4 joules (P < 0.006) and; in 5 of the 8 dogs with VT, theVT could be initiated with somewhat less aggressive stimulation. Significant beneficial electrophysiological effects were noted on theVT cycle length, including a proportionately prolonged overdrive pacing cycle length for VT termination. These changes were contrasted by the significant increase in the VF conversion energy required and the ease with which the VT could be induced postmoricizine. These findings suggest a possible proarrhythmic effect of moricizine.
Single Physician Approach to Radiofrequency Catheter Ahlation in Patients with Supraventricuiar Tachycardia
Authors: ROSENHECK SHIMON , SHARON ZEHAVA , WEISS ALEXEY , AGMON YORAM , WEISS AVRAHAM T. , GOTSMAN MERVYN S.
Published: July 2006

The minimal requirements for safe and effective performance of catheter ablation using radio/requency current are still unclear. To determine the feasibility and safety of single physician approach to catheter ablation of supraventricuiar tachycardia substrate using radio‐frequency energy, the results of the ablation procedure in 52 consecutive patients were evaluated. The procedures were performed during 1 year by the same physician and nurse. Twenty‐one patients had selective atrioventricuJar (AV) nodal pathway ablation and 31 patients had accessory AV pathway ablation. Forty‐eight patients (89%) had the diagnostic and the ablative procedure during the same electrophysiological test. In the 21 patients with AV nodal reentrant tachycardia, all had successful selective ablation of the fast (13) or the slow (8) pathways. Eight patients had recurrence of the clinical tachycardia and had a successful reablation. No patient developed complete AV block or other significant complications. The mean fluoroscopy time during the procedure was 16.0 ± 8.6 minutes. In the eight patients with Wolff‐Parkinson‐White syndrome, all concealed accessory pathways were successfully ablated with a mean fluoroscopy time of 30.0 ± 27.9 minutes. Two patients had recurrence of the conduction through the accessory pathway and had a successful reablation. Eighteen of 19 patients with a single overt accessory pathway had successful ablation, with a fluoroscopy time of 22.7 ± 20.6 minutes. Three patients had an early recurrence of the conduction through the accessory pathway, reablation was successful in two of them. Ten accessory pathways were ablated in four patients with multiple pathways during nine procedures. Only two patients developed minor peripheral vascular complications. Radiofrequency ablation of supraventricular tachycardia substrates may be performed effectively and safely by a small team just of one physician and one nurse.
A New Approach to Percutaneous Subclavian Venipuncture to Avoid Lead Fracture or Central Venous Catheter Occlusion
Authors: MAGNEY JEAN E. , STAPLIN DAVID H. , FLYNN DAVID M. , HUNTER DAVID W.
Published: July 2006

Pacemaker and defibrillator leads and central venous catheters placed by commonly recommended techniques have been found to pass through the subclavius muscle, the costocaracoid ligament, or the costoclavicular ligament before entering veins medial to the first rib. Entrapment by these soft tissues subjects leads and catheters to stresses imposed by movements of the ipsilateral upper extremity. Accordingly, a new approach has been developed that introduces the lead or catheter into the subciavian vein near the lateral border of the first rib. This placement avoids soft tissue entrapment and may extend the longevity of leads and catheters.
Delayed Response to Radiofrequency Ablation of Accessory Connections
Authors: DICK MACDONALD , DOROSTKAR PARVIN C. , SERWER GERALD , LEROY SARAH , ARMSTRONG BRIAN
Published: July 2006

This article summarizes delayed interruption in anomalous conduction through accessory connections following radiofrequency ablation attempts in three patients. The time course of the delayed interruption in accessory connection conduction suggests that such an effect is unlikely to occur after the first week following unsuccessful radiofrequency ablation.
Doppler Echocardiographic Assessment of the Hemodynamic Benefits of Rate Adaptive AV Delay During Exercise in Paced Patients with Complete Heart Block
Authors: SHEPPARD ROBERT C. , REN JIAN‐FANG , ROSS JOHN , McALLISTER MICHAEL , CHANDRASEKARAN KRISHNASWAMY , KUTALEK STEVEN P.
Published: July 2006

To determine if rate adaptation of the atrioventricular (AV) delay (i.e., linearly decreasing the AV interval for increasing sinus rate) improves exercise left ventricular systolic hemodynamics, we performed paired maximal semi‐upright bicycle exercise tests (EXTs) on 14 chronotropically competent patients with dual chamber pacemakers. Nine patients with complete AV block (CAVB) and total ventricular pacing dependence during exercise comprised the experimental group. Pacemakers in these patients were programmed randomly to rate adaptive AV delay (AVDR) for one EXT and fixed AV delay (AVDF) for the other EXT. AVDF was 156 msec; AVDR decreased linearly from 156–63 msec from rates of 78–142 beats/min. The other five patients had intact AV conduction and comprised the control group who were exercised in identical fashion while their pacemakers were inhibited throughout exercise io assure reproducibility of hemodynamic measurements between EXTs. Cardiac hemodynamics were calculated using measured Doppler echocardiographic systolic aortic valve flows recorded suprasternally with an independent 2‐MHz Doppler transducer during a graded ramp exercise protocol. For analysis, exercise was divided into four phases to compare Doppler measurements at submaximal and maximal levels of exercise, rest, early exercise (1st stage), late exercise (stage preceding peak), and peak. Patients achieved statistically similar heart rates between EXTs at each phase of exercise. Although at lower levels of exercise cardiac hemodynamics did not differ, experimental patients (with CAVB) showed a statistically significant benefit to cardiac output at peak exercise with heart rates of 129 ± 13 beats/min (AVDR: 9.4 ± 2.8 L/min; AVDE: 8.2 ± 2.6 L/min, P = 0.002), stroke volume (AVDR: 74.1 ± 25.6 mL; AVDF: 64.3 ± 24.4 mL, P = 0.0003), and aortic ejection time (AVDR: 253.3 ± 35.7 msec; AVDF: 226.7 ± 35.0 msec, P = 0.002). Duration of exercise, peak rate pressure product, peak aortic flow velocities, and acceleration times did not differ. In contrast, control group patients (intact AV conduction throughout exercise) showed no statistical differences between any hemodynamic parameters measured at any phase of exercise from the first to second exercise test. These data demonstrate that systolic cardiac hemodynamics measured echocardia‐graphically at the high heart rates achieved with peak exercise are improved with AVDR compared to AVDF in chronofropically competent patients with complete AV block. This is due primarily to improved stroke volume and a longer systolic ejection time with AV delay rate adaptation.
Palpitations Occur Frequently Following Radiofrequency Catheter Ablation for Supraventricular Tachycardia, But Do Not Predict Pathway Recurrence
Authors: MANN DAVID E. , KELLY PATRICIA A. , ADLER STUART W. , FUENZALIDA CHARLES E. , REITER MICHAEL J.
Published: July 2006

Radiofrequency ablation of extranodal pathways is an effective treatment for supraventricular tachycardia, but late recurrences of pathway conduction do occur. To determine if recurrence of palpitations following ablation predicts pathway recurrence, we interviewed 77 patients who were at Jeast 4 weeks status‐post successful ablation of an accessory pathway (43 overt, 11 concealed)or a slow pathway (23)for AV nodal reentrant tachycardia. Palpitations were reported by 45 (58%)patients postablation, and 28 (36%)patients reported palpitations lasting ≥10 seconds and/or felt their symptoms represented recurrent tachycardia (major palpitations). Repeat electrophysiological testing was performed 3 months postablation in 53 patients, including 34 patients with palpitations (22 with major symptoms). Eight (10%)patients had recurrent pathway conduction demonstrated on repeat testing: two had no symptoms prior to restudy and six had major symptoms. One patient had major symptoms, but was found to have inducible atrial tachycardia and not pathway recurrence on restudy. Thus, 15 (68%)of 22 patients with major symptoms who were restud‐ied had no pathway recurrence or inducible arrhythmia to explain their symptoms. Of the 24 patients not restudied, none has had documented recurrent tachycardia or overt pathway conduction by electrocardiogram over a mean follow‐up of 335 ± 138 (range 132–616)days. Thus, palpitations, including palpitations reminiscent of preablation symptoms, are common following radiofrequency ablation and often do not predict pathway recurrence. Repeat electrophysiological testing is frequently required to document long‐term success of radiofrequency ablation for supraventricular tachycardia in patients with recurrence of major symptoms.
Feasibility of Measuring Relative Right Ventricular Volumes and Ejection Fraction with Implantable Rhythm Control Devices
Authors: CHIRIFE RAUL , ORTEGA DANIEL F. , SALAZAR ADRIANA I.
Published: July 2006

Ejection fraction (EF), the ratio between stroke volume (SV) and end‐diastolic volume (EDV), is a valuable contractility indicator. Unlike SV, the Frank‐Starling effect is automatically compensated in the calcuIation of EF. It was the aim of this study to evaluate the physiological behavior of impedance derived measurements of relative right ventricular (RV)volumes and EF, obtained with standard pacing leads. Seven patients were evaluated at the time of pacemaker implant or replacement. Since no absolute standard of comparison was available for RV volumes, the value of the measurements was assessed hy observing their behavior under cardio‐circulatory challenges. A 2.5‐kHz carrier was fed to the ring and tip electrodes of standard bipolar pacing leads and the resulting voltage was digitized and stored. The peak‐to‐peak voltage (PPV)of the carrier at the time of QRS was used as EDV, and the largest PPV as end‐systolic volume (ESV). Relative SV was the difference between EDV and ESV, and EF = SV/EDV × 100. Pacing was used to reduce EDV, and the effect of contractility was tested with isometric hand grip, recumbent leg exercise, or isoproterenoi drip. Only minimal changes in EF were noted during incrementaJ pacing; relative SV and EDV decreased as expected; and EF increased significantly during contractility challenges. A high correlation coefficient was observed between EDV and SV changes induced hy incremental pacing at rest (r values from 0.62 to 0.98, P from < 0.01 to 0.001). The study revealed that impedance volumetry, utilizing conventional bipolar pacing leads, yields useful hemodynamic data related to EDV, ESV. and EE. Given the simplicity of the method, it is reasonable to conclude on the feasibility of using said impedance derived hemodynamic parameters in implantable rhythm control devices.
Radiofrequency Catheter Ablation of Ventricular Tachycardia Following Implantation of an Automatic Cardioverter Defibrillator
Authors: WILLEMS STEPHAN , BORGGREFE MARTIN , SHENASA MOHAMMAD , GHEN XU , HINDRICKS GERHARD , HAVERKAMP WILHELM , WIETHOLT DIETMAR , BLOGK MICHAEL , BREITHARDT GÜNTER
Published: July 2006

The present study reports on the complementary role of two nonpharmacological options of antiarrhythmic therapy. Background: Catheter ablation, antitachycardia surgery, and the implanfahie cardioverter de/ibrillator (ICD)have become important tools in the management of ventricuiar tachyarrhythmias. However, the emergence of ventricuiar tachyarrhythmias after implantation of an ICD is possihie because the arrhythmogenic suhstrate is not affected. Patients and Methods:Six of 180 patients developed frequent episodes of monomorphic ventricular tachycardia (n = 2) or incessant ventricular tachycardia (n = 4) following implantation of an ICD and underwent radio/requency (RF)catheter ablation. Catheter ablation was performed using a HF generator HAT 200. Energy was delivered between a 4‐mm tip electrode of the ahiation catheter and a patch electrode. Results: Catheter ablation was done 6.8 ± 5 months following ICD implantation; 6 ± 2.2 RF impulses were delivered at the site of origin of ventricuiar tachycardia chararcterized by early endocardial activation during ventricular tachycardia, identical pace mapping and long latency between stimulus, and QRS‐complex in five patients. New bundle branch reentry was the underlying mechanism of ventricular tachycardia in one patient. RF catheter ablation resulted in termination o/ incessant ventricular tachycardia. Immediately postabiation, the documented ventricular tachycardia was rendered noninducible in all patients. No ICD malfunctions have been observed. One patient died due to heart failure 24 hours after successful ablation of the incessant ventricular tachycardia. During a follow‐up of 5–19 months, episodes of ventricular tachycardia recurred in four patients. All episodes could be controlled by the ICD without frequent cardioversions. Conclusion: RF catheter ablation is o complementary therapeutic option in case of frequent or incessant ventricular tachycardia after ICD implantation.
Interference From a Hand Held Radiofrequency Remote Control Causing Discharge of an Implantahle Defibrillator
Authors: MAN K. CHING , DAVIDSON THERESA , LANGBERG JONATHAN J. , MORADY FRED , KALBFLEISGH STEVEN J.
Published: July 2006

A 46‐year‐old man with a history of sustained monomorphic ventricular tachycardia underwent an implantation of a third generation multiprogrammable implantable cardioverter defibrillator. One year post implant, while manipulating a remote control to a radiofrequency modulated toy car, the patient experienced a defibrillator discharge not preceded by an arrhythmia prodrome. Subsequent interrogation of the defibrillator revealed that a 34‐ioule shock had been delivered and had been preceded by RR intervals ranging from 141–406 msec, consistent with sensing lead noise. The remote control utilizes a 12‐volt battery and has a carrier frequency of 75.95 MHz and a modulating frequency of 50 Hz. Evaluation of the remote control and de/ibrillator interaction revealed that the remote control was able to trigger tachyarrhythmia sensing and reproduce the clinical episode. Interference was present only when the remote control was within 8 cm of the pulse generator and at specific angles relative to the device and only when the antenna length was > 45 cm. Interference was eliminated when a ground wire was attached to the antenna and when an aluminium shield was placed between the pulse generator and the remote control. This case report suggests that patients with third generation multiprogrammable defibrillators should be cautioned against close contact with potential sources of electromagnetic interference, such as remote control units.
Alterations of Orthodromic Circus Movement Tachycardia by Dual Atrioventricular Nodal Pathways in a Patient with Wolff‐Parkinson‐White Syndrome
Authors: KREINER GERHARD , HEINZ GOTTFRIED , SIOSTRZONEK PETER , RADOSZTICS SUSANNE , GÖSSINGER HEINZ DAVID
Published: July 2006

In a patient with a left sided accessory pathway (AP) three different types of orthodromic circus movement tachycardia were observed; (1) narrow QRS complex tachycardia with a stable cycle length (CL); (2) wide QRS complex tachycardia with a functional bundle branch block ipsilateral to the AP, which, paradoxically, had a shorter CL. The decrease in CL was due to a decrease of the AH interval; and (3) narrow QRS complex tachycardia with alternating CL, due to alternations of the AH interval. These phenomena were attributed to a concomitant dual airioventricular (AV) node, which was eventually proven after successful catheter ablation of the AP.
A Simplified Method for Implantation of Automatic Cardioverter Defibrillator in Patients with Previous Cardiac Surgery
Authors: SHAPIRA OZ M. , ALDEA GABRIEL S. , SHEMIN RICHARD J.
Published: July 2006

Patients with Previous Cardiac Surgery. A method of extrapericardial automatic cardioverter defibrillator implantation using bilateral limited anterior thoracotomy approach is described. The approach was used in six patients who have had previous open heart surgery. The defibrillation threshold was 15 joules in four patients and 20 joules in two. One patient died of pulmonary embolism in the tenth postoperative day. All patients were extubated within 0–18 hours. Drainage of a recurrent pleural effusion was required in one patient. This approach was found io be simple, safe, and effective in patients with previous median sternotomy. It may also be useful in patients in whom a cardiac operation may be indicated later in the course of their disease.
Rapid Resolution of New Right Bundle Branch Block in Acute Anterior Myocardial Infarction Patients after Thromholytic Therapy
Authors: ROTH ARIE , MILLER HYLTON I. , GLICK AHRON , BARBASH GABRIEL I. , LANIADO SHLOMO
Published: July 2006

The objectives of this retrospective study are to describe the effect of thrombolytic treatment on the clinical course of patients with acute anterior myocardial infarction complicated by acute right bundle branch block. Patients admitted to the intensive cardiac care unit vvilhin < 4 hours from onset of symptoms, and demonstrating an acute right bundle branch blockwith, or without left axis deviation, on the qualifying ECG were included. AIJ were given intravenous thrombolytic treatment consisting of: streptokinase (1.500,000 IU/40 min) or recombinant tissue type plasminogen activator (120 mg/6 hoursj. Following admission, patients were continuously monitored and a 12‐lead ECG was recorded during each of the first 3 hours and then every 3 hours over the next 21 hours. Eight patients were included (8/211 = 3.8%). Their mean age was 62 ± 7 years and time eJapse from onset to treatment was 122 ± 26 minutes. Complete resolution of the right bundle branch block occurred within < 3 hours in alJ and left axis deviation normalized in two patients. Mean peak creatine kinase wos 1214 ± 604 IU and global left ventricular ejection fracfion, measured by isotope ventriculography within 24 hours from admission, was 39%± 15%. Only one patient was prophylactically paced. In the others, rapid normalization of the conduction block with reperfusion exceeded the logistics required for the transvenous pacemaker implantation procedure. Coronary angiography performed in six patients during 72 hours from admission revealed high grade stenoses in the proximal portion of the left anterior descending coronary artery in five patients and complete occlusion in one. Clinical course was generally uneventful and patients were discharged with a mean ejection fraction of 38%± 15%. Thus, patients presenting with anterior myocardial infarction accompanied by a new right bundle branch or bifascicular block are not necessarily candidates for transvenous temporary pacing and may benefit from revascularization.
Comparison of Fixed Burst Versus Decremental Burst Pacing for Termination of Ventricular Tachycardia
Authors: CALKINS HUGH , EL‐ATASSI RAFEL , KALBFLEISCH STEVE , LANGBERG JONATHAN , MORADY FRED
Published: July 2006

The objective of this study was to compare prospectively the efficacy of fixed burst pacing with that of decremental hurst pacing in terminating VT. Forty‐four patients with inducible sustained monomorphic VT were studied. The efficacy of fixed burst and decremental burst pacing in terminating 57 distinct types of VT were compared during 50 eiectrophysiology tests fmean VT cycle length = 334 ± 84 msec. Termination of each type of VT was attempted with fixed burst and decremental burst pacing, Both pacing algorithms were delivered in an adaptive fashion with an increasing number of stimuli with each successive attempt at VT termination. Seventy percent of VT episodes were successfully terminated with fixed burst pacing, The mean number of stimuli required for VT termination was 5 ± 2. Seventy‐two percent of VT episodes were successfully terminated with decremental burst pacing. The mean number of stimuJi required for VT termination ivas 5 ± 2. For fixed burst and decremental burst pacing, the efficacy of VT termination was greater for VTs with a cycle length > 300 msec than for faster VTs (P < 0.05). The efficacy of VT termination and the incidence of VT acceleration were no different for the two pacing algorithms (P > 0.1). The results of this study demonstrate that fixed burst and decrementai burst pacing are equally effective in terminating VT and that a single adaptive pacing algorithm is effective in terminating nearly three fourths of VTs.
Adenosine Induced Intraatrial Block
Authors: ENGELSTEIN ERICA D. , LERMAN BRUCE B.
Published: July 2006

Adenosine, an endogenous nucleoside with potent negative chronotropic and dromotropic effects on the sinus and AV nodes, is thought to have little if any antiarrhythmic effect on normal atrial tissue. However, there may be an electrophysiological basis for an adenosine effect on atrial tissue with atypical conduction properties. We examined the electrophysiological effects of adenosine in a patient with decremental atrial conduction properties. During incremental pacing from the high right atrium there was gradual prolongation of the intraatrial interval between the high right atrium and the low septal atrium, from 180 to 280 msec, until 2:1 intraatrial block occurred at a pacing cycie length of 280 msec. Adenosine (6 mg IV) resulted in transient intraatrial block followed by prolonged intraatrial conduction during high right atrial pacing at a cycle length of 400 msec. Thus, similar to its effects on the AV node and decremental AV accessory pathways, adenosine may also slow and abolish conduction in decremental atrial issue, an effect that is likeiy attributed to adenosine induced hyperpolarizing K+ current in partially depolarized atrial tissue.
Clinical Results with Nonthoracotomy ICD Systems
Authors: HAUSER ROBERT G. , KURSCHINSKI DOUGLAS T. , McVEIGH KEVIN , THOMAS ANDRA , MOWER MORTON M.
Published: July 2006

The results of two separate US Food and Drug Administration clinical trials that involved endocardial and epicardial leads were compared with regard to patient demographics, detection and conversion characteristics, and subsequent clinical course including long‐term survival experience. The patient groups, although not strictly contemporaneous, were sufficiently similar to allow meaningful comparisons. There were no significant differences in detection of induced arrhythmias and ability to convert them. The surgical mortality, infection rate, and incidence of other morbid complications were lower in patients who had received endocardial leads; however, the differences did not reach statistical significance. Survivals through 1 year of follow‐up were uniformly high. These results suggest that the performance of the endocardial lead system is comparable to existing epicardial leads in similar patient populations.
Initial Experience with Transvenous Implantable Cardioverter Defibrillator Lead Systems: Operative Morbidity and Mortality
Authors: FRAME ROSEMARY , BRODMAN RICHARD , GROSS JAY , HOLLINGER INGRID , FISHER JOHN D. , KIM SOO G. , FERRICK KEVIN , ROTH JAMES , FURMAN SEYMOUR
Published: July 2006

Introduction of non‐thoracotomy lead systems™ (Medtronic, Inc.) for the implantable cardioverter defibrillator (ICD) has expanded the indications for use of this mode of therapy. Patients previously considered “too ill” to undergo a thoracotomy as well as patients who are at a high risk for developing sudden death but without previous cardiac arrest, are now considered candidates. The initial experience with the non‐thoracotomy lead system at our institution was analyzed for morbidity and mortality. Thirty‐four patients underwent attempted intravascular lead implantation, with 30 having initial successful implantation (88.2%). There were 23 males; average ejection fraction (EF) was 38.6%. Three patients developed pulmonary edema and low output immediately after the procedure. Three patients developed electromechanical dissociation during defibrillation threshold testing. A prolonged testing time for the non‐thoracotomy lead system was noted when compared to the thoracotomy system (57.39 vs 32.30 min; P < 0.0000). There were more intraoperative morbidities with the non‐thoracotomy leads than with the thoracotomy system. There were no perioperative deaths. The potential consequences of prolonged anesthesia time and extensive defibrillation threshold testing should be considered when choosing the route of ICD implant, the type of anesthesia, and the intraoperative testing protocol for each patient.
Changing Trends in Therapy Delivery with a Third Generation Noncommitted Implantable Defibrillator: Results of a Large Single Center Clinical Trial
Authors: LUCERI RICHARD M. , HABAL SALEM M. , DAVID IRVING B. , PUCHFERRAN RICHARD L. , MURATORE CLAUDIO , RABINOVICH RAFAEL
Published: July 2006

Thirty‐four patients underwent implantation of a third generation ICD, the 4210 ATP, for sudden cardiac death or ventricular tachycardia. This device incorporates significant telemetry logs as well as a detailed analysis of each arrhythmia episode detected. During the period of clinical follow‐up, a mean of 12.2 months, a total of 26,569 VT or VF detections were made. The vast majority of these were either due to atrial fibrillation, nonsustained VT, or “noise” detection, and only 6% led to device therapy. ATP was successful in 86.3% of episodes, with 3.5% accelerations and 2.4% failure of ATP trains. The majority of inappropriate therapy episodes were clustered in seven patients, and all were easily diagnosed with the aid of the extensive telemetry Jogs and sense histories. Of five late deaths, three were from congestive heart failure, one from cerebrovascular accident, and one unknown. These data reveal that this “tiered” therapy noncommitted ICD performs to expectations; the stored data is of significant value in diagnosing the cause of ICD therapy. In addition, ATP is an effective modality for termination of VT.
The Antitachycardia Pacing ICD: Impact on Patient Selection and Outcome
Authors: GROSS JAY N. , SACKSTEIN ROBERT D. , SONG SUSAN L. , GHANG CHEE JEN , KAWINISHI DAVID T. , FURMAN SEYMOUR
Published: July 2006

Implantable cardioverter defibrillators (ICD) currently undergoing clinical investigation incorporate antitachycardia pacing capabilities, but little is known about their effect on patient selection and outcome. The Bilitch registry database was reviewed to compare the 1,553 patients who initially received standard devices with the 242 patients initially implanted with antitachycardia pacing ICDs (ANT). Baseline characteristics including mean age, ejection fraction, sex, type of cardiac disease, and percent presenting with sudden cardiac death were reviewed. Cumulative first shock occurrence and survival from arrhythmic and ail cause mortality were calculated for the two groups. Results: Patient characteristics were similar in the two groups except that the ANT population had a greater male predominance and initially presented with a lower sudden cardiac death incidence (P < 0.05). Cumulative occurrence of first shock was significantly lower in the ANT group up to 24 months of follow‐up (28% vs 36%, P < 0.05). ANT group survival from arrhythmic death (99% vs 96%) and all cause mortality (89% vs 94%) was significantly higher at 24 months of follow‐up (P < 0.05). Conclusions: The addition of antitachycardia pacing to ICD therapy appears to significantly limit the occurrence of first ICD shock without adversely affecting mortality in a patient population similar to those implanted with standard ICDs.