bluuebunny/crossref_metadata_2025 huggingface dataset:
Transcatheter Radiofrequency Ablation of Atrial Tissue Using a Suction Catheter
Authors: LAVERGNE Th. , PRUNIER L. , CUIZE L. , BRUNEVAL P. , VON EUW D. , LE HEUZEY J‐Y. , PERONNEAU P.
Published: July 2006

Closed chest ablative technique that avoid barotrauma would be attractive for ablation at thin walled cardiac structures, such as the atrial free wall or coronary sinus. Transcatheter radiofrequency (RF) currents produce tissue necrosis the size of which is dependent on the contact between the tissue and the electrode. In order to assess the effects of transvenous RF ablation of atrial free wall using a suction electrode catheter, we delivered in ten dogs, one single unmodulated RF pulse 1.2 MHz, in a unipolar mode, through the distal electrode of a lumen catheter (USCI 8F) (USCI, Billerica, MA, USA) located in the right appendage. During the pulse an 80 KPa vacuum depression was applied to the lumen of the catheter. Each pulse had a 10 seconds duration and the mean delivered power was 4.3 ± 1.4 W. Aortic pressure and electrocardiogram were monitored during the procedure. A right airial electrophysiological study was performed at the ablated site, at control, after suction application and after RF pulse delivery. The animals were sacrificed after 14 or 21 days. Atrial pacing threshold values decreased after suction application in comparison to control values after the pulse (0.42 ± 0.06 vs 0.60 ± 0.23 mA, P < 0.05) but increased after the pulse delivery (2.60 ± 1.85 mA, P < 0.01). In contrast, the atrial effective refractory period did not significantly change after suction, nor after RF pulse delivery. Aortic pressure remained unchanged throughout the procedure. Complex arrhythmias were not observed during or after RF pulse delivery. One dog died suddenly at the first day after ablation, but this death was most probably unrelated to RF ablation. Anatomic lesions had a length of 8.8 ± 3.3 mm, a width of 4.6 ± 2.5 mm and a depth of 3.6 ± 1.1 mm. They were transmural in nine of the ten dogs but without atrial wall perforation in any case. Lesions suggesting tissue volatilization were present in four dogs. These results demonstrate that low energy RF currents delivered with a suction electrode catheter can produce transmural necrosis of free wall, without risk of perforation. Such ablative technique would be of interest for ablation of right sided accessory pathways or atrial ectopic foci. Further experimental data are required in order to define the optimal energy level required to avoid tissue volatilization.
Localization of Left Free‐Wall and Posteroseptal Accessory Atrioventricular Pathways by Direct Recording of Accessory Pathway Activation
Authors: JACKMAN WARREN M. , FRIDAY KAREN J. , FITZGERALD DAVID M. , BOWMAN ANTHONY J. , YEUNG‐LAI‐WAI JOHN A. , LAZZARA RALPH
Published: July 2006

With the advent of catheter ablation techniques, precise localization of accessory AV pathways (AP) assumes greater importance. In an efort to define the course of AP fibers, we attempted to record activation of 56 left free‐wall and 23 posteroseptal APs in 62 patients undergoing eiectrophysiological study. The coronary sinus (CS) and great cardiac vein (GCV) were mapped using orthogonal catheter electrodes, which provide a recording dipole perpendicular to the AV groove. The tricuspid annulus (TA) was mapped using a 2 mm spaced octapolar electrode catheter. Potentials were considered to represent AP activation only if they could be dissociated from both atrial and ventricular activation by programmed stimulation. Orthogonal catheter electrodes in the CS and GCV were advanced heyond the site of earliest retrograde atrial activation and/or earliest antegrade ventricular activation in 45 of the 56 left free‐wall APs, and AP potentials were recorded from 42 (93%). An oblique course was identified in 36 APs, with the ventricular insertion being recorded 4–30 mm (median 15 mm) distal or anterior to the atrial insertion. In three patients, antegrade and retrograde conduction proceeded over different (but close) parallel fibers. AP potentials were recorded from 19 of 23 posteroseptal pathways. Ten pathways (left posteroseptal) were recorded from the CS, beginning 5–11 mm (median 9 mm) distal to the os, with potentials extending 8–18 mm (median 11 mm) distally. Four pathways (midseptal) were recorded along the TA, anterior to the CS ostium and posterior to the His bundle catheter. Five pathways (right posteroseptal) were recorded along the TA, directly opposite or immediately posterior to the CS ostium. One of the patients had both midseptal and left posteroseptal pathways and three patients had both right posteroseptal and left posteroseptal pathways. We conclude: 1) left free‐wall APs transit the AV groove obliquely and may be comprised of multiple, closely spaced, parallel fihers; 2) the anatomical location of “posteroseptal” pathways is variable and the presence of fibers at multiple sites is common; and 3) direct recordings of AP activation facilitate tracking of the accessory pathway along its course from atrium to ventricle and help identify the presence of multiple fibers.
Results of Catheter Ablation of Ventricular Tachycardia Using Direct Current Shocks
Authors: MORADY FRED , SCHEINMAN MELVIN M. , GRIFFIN JERRY C. , HERRE JOHN M. , KOU WILLIAM H.
Published: July 2006

Thirty‐three patients with recurrent ventricular tachycardia (VT) underwent catheter ablation with direct‐current shocks. One to four shocks of 100–300 joules were delivered to the presumed VT exit sites as identified by endocardial mapping and pace mapping. Fifteen patients (45%) had no recurrence of symptomatic VT during a follow‐up interval of 15.5 ± 10 months (mean ± standard deviation). Five patients experienced six nonfatal complications (new VT or ventricular fibrillation, transient neurological deficit, atrioventricular block, brachial artery thrombosis). In conclusion, catheter ablation in selected patients with recurrent VT has the potential for preventing recurrences of VT over the long‐term and is relatively safe.
Spinal Cord Stimulation for Severely Ischemic Limbs
Authors: SAMPÈRE CARLOS TULIO , GUASCH JORGE ALBERTO , PALADINO CARLOS MARIA , CASALONGUE MANUEL SÁNCHEZ , ELENCWAJG BENJAMIN
Published: July 2006

Severe atherosclerosis of the lower limbs causes rest pain, skin ulcerations and gangrene. In such situations and when standard surgical treatment had failed or it is impossible to employ, spinal cord stimulation (SCS) seems to he of value. Since April 1985, we have used this technique on 19 patients. The results have been beneficial in 70.6% of the cases and have shown some evidence of increasing cutaneous flow. However, randomized series are required before accepting it as having a special place in the fight against atherosclerotic disease.
Short‐Term Thrombosis after Transvenous Permanent Pacemaker Insertion
Authors: ANTONELLI DANTE , TURGEMAN YOAV , KAVEH ZVI , ARTOUL SAMIR , ROSENFELD TIBERIO
Published: July 2006

In order to assess prospectively the incidence and significance of venous thrombosis early after permanent transvenous pacemaker implantation venographic studies were carried out in 40 consecutive patients. The venograms performed between 1 and 6 months (mean 4 months) after the implantation were normal in 31 patients (77%), in six patients (15%) they showed partial venous obstruction and in three patients (8%) total obstruction. Between 6 and 12 months (mean 9 months) the venograms of five patients, that were previously normal, showed partial venous thrombosis. No changes were found in (he venograms performed later. Only two of 14 patients with thrombosis of the great veins was clinically symptomatic and developed arm edema, that resolved spontaneously within about a month. No difference in incidence of abnormal venograms was found according to the type of insulation, the polarity of the electrode and the route of entry.
The Electrophysiological Effects of Alpha‐Chloralose Anesthesia in the Intact Dog: (1) Alone and (2) in Combination with Verapamil
Authors: SCHWARTZ JANICE B. , HERRE JOHN M.
Published: July 2006

The electrophysiological effects of alpha‐chloralose anesthesia were determined in 13 chronically instrumented dogs and compared to baseline electrophysiological parameters in the conscious state. Alpha‐chloralose anesthesia (75 mg/kg of a 4% solution in polyethylene glycol (PEG) delayed conduction and prolonged refractoriness of the AV node: (1) the P‐R interval increased from 108 ± 14 msec (mean ± SD) in the conscious state to 125 ± 23 msec (P < 0.02); (2) the A‐H from 98 ± 12 msec to 108 ± 16 msec (P < 0.04); (3) the AV nodal effective refractory period from 136 ± 36 to 153 ± 29 msec (P = .05) and the AV nodal functional refractory period from 232 ± 58 to 247 ± 46 msec (P = 0.07); and (4) the AV block cycle iength from 228 ± 54 msec to 248 ± 43 msec (P < 0.04). Chloralose anesthesia also increased the ventricular refractory period from 139 ± 13 msec to 161 ± 22 msec (P < .03) and the QTc interval from 273 ± 22 to 306 ± 32 msec fP < 0.0002). To determine whether these effects on AV nodal conduction would influence experimental results, responses to verapamil were studied in the conscious state and during chloraiose anesthesia. During chloralose anesthesia, (1) no relationship was detected between the sinus cycle length and verapamil concentrations; (2) a greater increment in AV conduction time was seen for a given verapamil concentration; and (3) AV block occurred at verapamil concentrations associated with 1:1 conduction in the conscious state. We conclude that chloralose anesthesia has significant electrophysiological effects and that these effects must be taken into consideration during the interpretation of experiments performed in animals during chloralose anesthesia. (PACE, Vol. 12 February 1989)
Reliability of Transesophageal Pacing in the Assessment of Sinus Node Function in Patients with Sick Sinus Syndrome
Authors: ALBONI PAOLO , PAPARELLA NELLY , CAPPATO RICCARDO , PEDRONI PAOLO , CANDINI GIAN CARLO , ANTONIOLI GIAN ENRICO
Published: July 2006

The purpose of this study was to find out whether fransesophageal pacing could be utilized for assessment of sinus node function in patients with sick sinus syndrome (SSS). In 17 patients with SSS (study group) we compared the results of sinus node tests obtained both in the basal state and after pharmacological autonomic blockade by endocavitary stimulation and, 24 hours later, by transesophageal pacing. In another group of 17 patients with SSS (control group), we compared the results obtained by two endocavitary studies. In “study group”, sinus cycle length (SCL) and corrected sinus node recovery time (CSRT) did not show significant differences between the two studies both in the basal state and after autonomic blockade, whereas sinoatrial conduction time (SACT) was more prolonged during esophageal pacing (P < 0.01). In “control group”, sinus node measures did not show significant differences between the two studies. In the “study group,” the following coefficients of correlation were obtained in the basal state: SCL, r = 0.65, CSRT, r ‐ 0.57, SACT, r = 0.52 and after autonomic blockade: SCL, r = 0.95, CSRT, r = 0.62 and SACT, r = 0.53. In the basal state, the correlation for SCL and CSRT between the two studies was lower in the “study group” than in the “control group” (P < 0.05), whereas after autonomic blockade the correlation for sinus node measures did not show significant differences between the two groups of patients. These data suggest that transesophageal study influences the autonomic tone regulating the sinus node; however, it is not responsible for important variations in sinus node measures. Thus, this noninvasive method appears useful for assessment of sinus node function in patients with SSS, considering, however, that SACT is more prolonged during pacing fram the esophagus.
Sinus Mapping in Patients with Cardiac Arrest and Coronary Disease—Results and Correlation with Outcome
Authors: KADISH ALAN H. , ROSENTHAL MARK E. , VASSALLO JOSEPH A. , CASSIDY DENNIS M. , BUXTON ALFRED E. , MARCHLINSKI FRANCIS E. , MILLER JOHN M. , JOSEPHSON MARK E.
Published: July 2006

Electrophysiological testing and left ventricular endocardial mapping in sinus rhythm were performed in 61 patients with coronary artery disease who presented with cardiac arrest in an attempt to relate the results of these studies to clinical outcome. Forty‐one patients (67%) had inducible sustained arrhythmias (18 uniform ventricular tachycardia, 23 polymorphic ventricular tachycardia/ventricular fibrillation) and 20 had no inducible arrhythmia. Patients with inducible arrhythmia had 45% abnormal and 6% fractionated electrograms versus 33% and 0% for those without inducible arrhythmia (P > 0.05 for both comparisons). Sixteen of 59 patients (27%) with adequate follow‐up had arrhythmia recurrence (11/39 [31%] with inducible arrhythmia and 5/20 [25%] without inducible arrhythmia) over a mean follow‐up period of 27 months. Of five patients without inducible arrhythmia who experienced recurrence, two did so despite the anti‐ischemic therapy. In the 20 patients without inducible arrhythmia, the 15 who remained arrhythmia‐free had a mean of 78 ± 22% normal sites versus 46 ± 24% normal sites in those with recurrence (P > 0.05). We conclude that in patients with coronary artery disease and cardiac arrest: 1) patients without inducible arrhythmia have less marked endocardial electrical abnormality than those with inducible arrhythmia, 2) those patients who have marked endocardial abnormality despite the lack of inducible arrhythmia are at risk for clinical recurrence which suggests that these abnormalities may represent an anatomic substrate for arrhythmia which cannot be identified by programmed stimulation, These patients are candidates for AICD implantation and 3) patients with relatively normal endocardial electrograms do well with anti‐ischemic therapy alone. (PACE, Vol. 12 February 1989)
Improved Pattern of Rate Responsiveness with Dynamic Slope Setting for the QT Sensing Pacemaker
Authors: BAIG M.W. , WILSON J. , BOUTE W. , BEGEMANN M.J.S. , COBBOLD J.P. , PERRINS E.J.
Published: July 2006

We have recently described the electrophysiological basis of a new algorithm for the QT (TX) sensing rate responsive pacemaker. By using the new software program running on the standard programmer it has been possible to simulate the new algorithm in ten patients with complete heart block (seven patients had implanted TX units and three were paced with an external TX pacemaker) during routine exercise testing. In this way a single‐blind, intra‐patient comparison of the pattern of pacing rote change using both the existing and new algorithms was possible. In nine out of the ten cases the time taken to increase the pacing rate from 70 to 80 bpm was reduced significantly when the new algorithm was used (P = 0.037). Additionally, the correlation between the atrial and ventricular rates in those patients with normal sinus node function (seven patients) was determined. In all cases we have observed a significantly improved correlation between the atrial and ventricular paced rates during exercise with the new algorithm (P < 0.001).
Reliability of Minute Ventilation as a Parameter for Rate Responsive Pacing
Authors: LAU CHU PAK , ANTONIOU ANNA , WARD DAVID E. , CAMM A. JOHN
Published: July 2006

A minute ventilation sensing rate responsive pacemaker was implanted in 11 patients with hradycardias. Their mean age was 59 ± 4 years (mean ± SEM). The pacemaker measures minute ventilation by sensing intravascular impedance using a standard bipolar electrode. The rate responsive programming was simple: apart from ascribing an upper and lower rate, the only programmable parameter was the slope of rate response. This could be derived approximately by assessing the suggested slope value during an exercise test in the ‘adaptive VVI’ mode. Compared with exercise in the VVI mode, symptom limited treadmill tests in the rate responsive mode showed a 33% improvement of exercise capacity and a 44% improvement of cardiac output as determined noninvasively by continuous wave Doppler measurements of the ascending aortic blood flow. The pacing rate was appropriately increased during a variety of daily activities such as walking at different speeds and gradients, and ascending and descending stairs. Voluntary interference of the respiratory pattern such as during coughing and hyperventilation increased the pacing rate from a resting rate of 70 bpm to 111 ± 10 and 86 ± 4 bpm respectively. Continuous talking during exercise attenuated the expected rate response. The pacemaker can sense activity induced by arm swinging.

In conclusion, the Meta pacemaker improved cardiac output and exercise capacity in patients with bradycardias. Its rate response was related to workload. Although voluntary interference affected the pacing rate, excessive rate acceleration was not encountered.
Treatment of Ventricular and Supraventricular Tachyarrhythmias by Transcutaneous Cardiac Pacing
Authors: ALTAMURA GIULIANO , BIANCONI LEOPOLDO , BOCCADAMO ROBERTO , PISTOLESE MICHELE
Published: July 2006

The efficacy of noninvasive transcutaneous cardiac pacing (TCP) in the treatment of tachyarrhythmic events was tested in 24 patients: 14 with ventricular tachycardia, seven with supraventricular tachycardia and three with atrial flutter. Six (42.9%) ventricular tachycardias were interrupted: in two of the ten patients on whom underdrive pacing was attempted and in all four cases in which overdrive stimulation was possible. Five of the six supraventricuiar tachycardias utilizing an atrioventricular bypass tract were interrupted, while the TCP was unsuccessful on the only patient with atrioventricular nodal reentrant tachycardia. TCP failed to interrupt the arrhythmia in the three cases of atrial gutter. No clinically significant untoward effects (in particular tachycardia acceleration or ventricular fibrillation) were observed, except for a tolerable thumping sensation on the chest during pacing. In four patients, TCP effects on cardiac activation was evaluated by endocavitary recording: while the mean ventricular threshold was 70 mA, atrial capture was possible on only two patients at a current intensity of 140 and 150 mA. We consider our preliminary experience with TCP in the treatment of tachycardias encouraging. The technique was easily and rapidly usable and it was immediately successful in the majority of atrioventricular reentrant tachycardias and in a relevant percentage of ventricular tachycardias. In this latter setting TCP was mostly effective in the slower tachycardias where overdrive pacing was possible. A further experience with devices provided by higher pacing rales is warranted.
Transvascular Argon Laser Ablation of Atrioventricular Conduction in Dogs: Feasibility and Morphological Results
Authors: CURTIS ANNE B. , ABELA GEORGE S. , GRIFEIN JERRY C. , HILL JAMES A. , NORMANN SIGURD J.
Published: July 2006

The purpose of this study was to ablate atrioventricular (AV) conduction in dogs with an argon laser using a transvascular approach. Six dogs were anesthetized and underwent a right thoracotomy and atriotomy. A bipolar #7 French lumen catheter containing a 400 u silica fiber was used to map the region of the AV junction. When a stable His deflection was obtained, the silica fiber was extruded from the end 0f the catheter and argon laser radiation was delivered for up to 20 s at 3.0–4.5 watts. In five of six dogs, complete heart block was successfully created after 3 to 15 lasings. A continuous His bundle electrogram in one dog showed gradual prolongation of the HV interval before the development of complete infrahisian block. The mean R‐R intervals in the five dogs with complete heart block increased from 435 ± 56 ms to 1216 ± 197 ms (P < 0.001], and the QRS duration increased from 78 ± 26 ms to 91 ± 19 ms (P = ns). Gross inspection showed multiple 1–2 mm2 craters in the atria just above the tricuspid valve ring. Complications included one instance each of aortic root perforation and creation of a small ventricular septal defect. These lesions were so small that there was no hemodynamic compromise in either animal in which they occurred and the lesions themselves were only detected on careful postmortem examination. Histology revealed two patterns of injury involved in conduction ablation. One was direct vaporizaton of tissue resulting in a wedge shaped incision and the other was formation of a hematoma and thermal necrosis at the lasing site with little evidence of tissue vaporizotion. Although catheter modifications are necessary to avoid perforation, this study demonstrates that ablation of conduction can be successfully accomplished using an argon laser.
Anxiety and Anger in Patients with Ventricular Tachyarrhythmias. Responses after Automatic Internal Cardioverter Defibrillator Implantation
Authors: VLAY STEPHEN C. , OLSON LINDA C. , FRICCHIONE GREGORY L. , FRIEDMAN RICHARD
Published: July 2006

In order to assess the psychological profile of patients with malignant ventricular tachyarrhythmias, eight patients who underwent implantation of the automatic internal cardioverter defibrillator for refractory arrhythmias were evaluated. Six men and two women with a mean age of 53 years were examined with the Symptom Checklist‐90, the State Trait Personality Inventory and a specifically designed questionnaire about the automatic internal cardioverter defibrillator. The group studied manifested high degrees of both anger and anxiety compared to normal controls or to other medically ill populations. The trait scores remained essentially unchanged before and after the AICD implantation. The state of anxiety was markedly reduced by 26 percentage points after implantation (P < 0.01), while the state of anger remained unchanged. In evaluating the number of AICD discharges, it was observed that the number of discharges in the first 6 months was higher than that observed in the subsequent follow‐up period (mean 30 months). The reduction in AICD discharges demonstrated a trend (P = 0.094). Patient acceptance of the automatic internal cardioverter defibrillator was high. They became accustomed to the pulse generator after a mean of 3.6 months. The defibrillator permitted resumption of normal activities. If the device became battery depleted, all patients would insist on replacement. The evaluation of this group of patients with malignant ventricular arrhythmias indicates a high degree of anxiety and anger, which potentially may influence outcome. The reduction in defibrillator discharges after the first 6 months in addition to a reduced state of anxiety is a relationship that merits further investigation. (PACE, Vol. 12 February 1989)
QT Sensing Rate Responsive Pacing Compared to Fixed Rate Ventricular Inhibited Pacing: A Controlled Clinical Study
Authors: HEDMAN ANDERS , NORDLANDER ROLE
Published: July 2006

Eighteen patients, five women and 13 men, fmean age 70 ± S.E.M. 2 years) treated with QT sensing rate responsive pacemakers due to symptomatic high degree AV block took part in a double‐blind study, comparing the rate responsive (TX) mode with fixed rate ventricular inhibited (VVI) pacing. The pacemaker was blindly programmed to either mode in a cross‐over design. During the 1 month period a daily diary of symptoms (chest pain, vertigo, dyspnea, and palpitations) was kept. At the end of each period, a mental stress test and an exercise test were performed. The patient rated the general well‐being and stated a preference for one of the modes. In the TX mode the heart rate was significantly higher at the end of exercise compared with WI (107 ± 4 vs 73 ± 3 bpm; P < 0.001) and the exercise tolerance was improved by 9% (104 ± 8 vs 96 ± 7 W; P < 0.01). The patients reported significantly less dyspnea and fatigue at comparable workloads with TX pacing. During the mental stress test the pacing rate increased by 10% in the TX mode (from 73 ± 2 to 82 ± 4 bpm; P < 0.001). There was a physiological rate variability on 24‐hour Holter monitoring. Ten patients reported a significant improvement in feeling of general well‐being in the TX mode. Eleven patients preferred the TX mode, five patients could not distinguish between the modes and two patients preferred the WI mode due to worsening of angina pectoris with TX pacing. This preference for the TX mode was significant (P < 0.05). The results of this controlled study indicate that TX is preferable to VVI in most cases, but the worsening of angina pectoris in two of the patients and the occurrence of rapid rate oscillations in a third patient are factors that warrant some caution in selecting patients.
Pregnancy and Cesarean Section in a Patient with a Rate‐Responsive Pacemaker
Authors: ANDERSEN CLAUS , OXHØJ HENRIK , ARNSBO PER , LYBECKER HANS
Published: July 2006

The function of a rate‐responsive pacemaker was monitored during pregnancy and cesarean section in a woman with complete atrioventricular block. The observations during pregnancy were compared to similar observations obtained in a pregnant normal woman of comparable age, height and weight, and in 12 normal women during elective cesarean section. During pregnancy, the heart rate increased in the normal woman, whereas the pacing rate in the woman with the implanted pacemaker was unchanged. Fetal movement caused an increase in pacing rate in the 37th week of gestation, whereas the heart rate in the normal woman did not respond. During cesarean section the pacing rate was generally within the mean ± 1 SD for normal women.
Circumvention of Maximum Tracking Limitations with a Rate Modulated Dual Chamber Pacemaker
Authors: HANICH ROBERT F. , MIDEI MARK G. , MCELROY BRYANT P. , BRINKER JEFFREY A.
Published: July 2006

A patient having high grade AV block with intact sinus node function is presented in whom DDDR pacing provided the benefit of preventing 2:1 pacemaker block in response to exercise‐induced sinus tachycardia. In paired treadmill tests with the patient blinded as to pacing mode, she was able to exercise longer (7.5 vs 6.6 METS) when programmed in DDDR than in DDDO. This is attributable to circumvention of 2:1 pacemaker block which had resulted in abrupt onset of fatigue and SOB (shortness of breath) when the sinus rate exceeded the maximum tracking rate of 130/min. Outpatient ambulatory electrocardiographic monitoring confirmed this phenomenon during relatively strenuous activity. The theoretic advantages of dual chamber rate modulated pacing compared to the DDDO and VVIR modes are discussed.
Subjective Consequences of Permanent Pacemaker Therapy in Patients Under the Age of Retirement
Authors: MICKLEY HANS , PETERSEN JAN , NIELSEN BENT LYAGER
Published: July 2006

During a 5‐year period, 81 patients ages 20 to 60 years old had implantation of a permanent cardiac pacemaker at the University Hospital, Odense. At follow‐up, during 1985, the 73 survivors received a semi‐structured questionnaire regarding subjective consequences of pacemaker therapy, and 72 people (98.6%) agreed to participate. The mean pacing period (range) was 33.8 (11–72) months. Surgical intervention was required in 14 patients (19.4%) during follow‐up. Regarding all symptoms 67 patients (93.1%) perceived benefit from the pacemaker. The effectiveness of cardiac pacing was most pronounced in subjects suffering from syncope and/or dizziness. Eight patients (11.1%) perceived anxiety most frequently due to fear of pacing failure. Physical complaints were present in 17 patients (23.6%), and the discomfort was mainly due to the size of generator, pain/tenderness from the scar or a sensation of “impulses”/palpitations. To the majority (49 patients or 68.1 %) pacemaker treatment did not influence quality of sexual activity. Six patients (8.3%) perceived an improvement, whereas a corresponding number felt deterioration in sexual activity following pacemaker implantation. Pacemaker therapy had not affected life quality in 30 (41.7%) of the patients. However 31 patients (43%) felt an improvement, and only a minority of ten patients (13.9%) perceived deterioration in quality of life owed to pacemaker therapy.
Asystole with Syncope Secondary to Hyperventilation in Three Young Athletes
Authors: BUJA GIANFRANCO , FOLINO ANTONIO F. , BITTANTE MARINA , CANClANI BRUNO , MARTINI BORTOLO , MIORELLI MANUELA , TOGNIN DANIELA , CORRADO DOMENICO , NAVA ANDREA
Published: July 2006

We describe three athletes who had syncope after (case 1) or during (cases 2, 3) hyperventilation. During the episode, ECG showed prolonged sinus arrest. Clinicai data and noninvasive investigations were normal and the phenomenon was not reproducible. Electrophysiological study after autonomic blockade allowed a prolonged intrinsic heart rate in case 1, and abnormal corrected sinus node recovery time in cases 1 and 2. During follow‐up, symptomatic sinus arrest provoked by deep inspiration occurred in case 3. These cases document prolonged asystole of unknown etiology, secondary to hyperventilation, and probably caused by different vagally‐mediated mechanisms.
Electrophysiologic Evaluation of Asymptomatic Patients with the Wolff‐Parkinson‐White Pattern
Authors: SATOH MASAHITO , AIZAWA YOSHIFUSA , FUNAZAKI TOSHIKAZU , NIWANO SHINICHI , EBE KATSUYA , MIYAJIMA SEIICHI , SUZUKI KAORU , AIZAWA MASAMI , SHIBATA AKIRA
Published: July 2006

In the past 4 years, 34 asymptomatic patients with the Wolff‐Parkinson‐White (WPW) pattern underwent electrophysiologic study. The effective refractory period (ERP) of antegrade conduction over the accessory pathway was 288 ± 29 msec. In three asymptomatic patients (9%), the antegrade ERP of the accessory pathway was shorter than 250 msec. The antegrade ERP of the accessory pathway became shorter than 250 msec in an additional 12 of 22 (55%) patients after isoproterenol administration. Nineteen (56%) of the asymptomatic patients showed the absence of retrograde conduction over the accessory pathway even after isoproterenol administration. The rate of induction of orthodromic reciprocating tachycardia in the asymptomatic WPW patients was 15% (5/34), which was significantly lower than that in the symptomatic patients. These data suggest that in the asymptomatic patients, the absence of retrograde conduction over the accessory pathway is the reason they remained asymptomatic, free of reciprocating tachycardia. However, even in the asymptomatic patients, some had the accessory pathway in which antegrade ERP was shorter than 250 msec. They may result in rapid ventricular conduction over the accessory pathway when atrial fibrillation develops.
Long‐Term Follow‐Up of Patients Treated with Automatic Scanning Antitachycardia Pacemaker
Authors: MØLLER MOGENS , SIMONSEN ERIK , ING PER ARNSBO , OXHØJ HENRIK
Published: July 2006

The long‐term efficacy of an automatic antitachycardia pacemaker was evaluated in 13 patients with supraventricular tachycardia and in two patients with ventricular tachycardia. Patients were followed for 4–53 months (median 16). The concertina scanning mode with 2–7 extrastimuli proved to be effective in all patients but one. During follow‐up, two patients had to be reoperated due to sensing problems. Atrial flutter was induced during scanning in one patient, termination mode was triggered by sinus tachycardia in one patient despite beta blocker therapy, and in one patient after cessation of beta blocker treatment. The pacemaker did not induce any serious arrhythmias and no sudden deaths occurred. Seven patients were given beta blockers, one patient with ventricular tachycardia was additionally administered amiodarone. In conclusion, the PASAR 4171 (Telectronics, Englewood, CO, USA) automatic scanning pacemaker is an alternative or adjunctive means to chronic antiarrhythmic drug therapy in patients with supraventricular tachycardia, but further versatility with regard to sensitivity, refractory period, and tachycardia recognition is required to eliminate the shortcomings observed, including the need for additional beta blocker therapy.
Toward Optimizing the Detection of Atrial Depolarization with Floating Bipolar Electrodes
Authors: BROWNLEE ROBERT R.
Published: July 2006

Some concepts derived from modern lilerature on the physics of cardiac muscle conduction regarding optimization of the design of electrode systems for detection of atrial depolarization and a preliminary clinical corroboration of the concepts are presented. The concepts of most import are 1) that the mechanical dimensions of sensing electrodes in all planes have to be as small as possible relative to the dimensions of the extracellular waveform dimensions associated with depolarization action potentials, and 2) that the distance between bipolar electrodes should be tuned to be greater than the dimensions of the extracellular waveform to avoid subtractive interference patterns associated with saltatory propagation in aging cardiac muscle. Additionally, in the practical application of chronic atrial sensing from a single lead far use in an implanted VDD pacing system, it is also important to consider electrode size and its effect on impedance level.
The Assumptions of Isochronal Cardiac Mapping
Authors: IDEKER RAYMOND E. , SMITH WILLIAM M. , BLANCHARD SUSAN M. , REISER SUSAN L. , SIMPSON EDWARD V. , WOLF PATRICK D. , DANIELEY NED D.
Published: July 2006

Isochronal maps of cardiac activation are commonly used to study the mechanisms and to guide the ablative therapies of arrhythmias. Little has been written about the assumptions implicit in the construction and use of isochronal cardiac maps. These assumptions include the following: (1) the location of the recording electrodes is known with sufficient accuracy to determine the mechanism of an arrhythmia or to guide therapy; (2) a single, discrete activation time can be assigned to each recording electrode location; (3) the presence or absence of activation at an electrode site can be reliably ascertained, and when activation is present, the time of activation can be determined with sufficient accuracy to specify the mechanism of an arrhythmia or to guide therapy; and (4) the recording electrodes are close enough together that the activation sequence can be estimated with sufficient accuracy to determine the mechanism of an arrhythmia or to guide therapy. The manuscript reviews evidence that these assumptions may not always be true, and when they are not, the isochronal map may be misleading.
Treadmill Assessment of an Activity‐Modulated Pacemaker: The Importance of Individual Programming
Authors: McALISTER HUGH F. , SOBERMAN JUDITH , KLEMENTOWICZ PETER , ANDREWS CAROLYN , FURMAN SEYMOUR
Published: July 2006

Maximum benefit from a rate‐modulated pacemaker requires individualized programming of rate response settings. We tested an externally strapped activity‐sensing pacemaker (Activitrax ‐ Medtronic 8400) in eight healthy volunteers, to assess the pacing responses of the different rate response and activity threshold settings. Five males and three females, aged 20 to 70 years (mean 40), performed a total of 67 treadmill exercise tests, using a specijic protocol designed to assess the activity‐sensing unit. The external unit was compared to implanted units in four patients, to validate its accuracy. A reproducible sinus response to the treadmill protocol was observed, against which pacing responses were compared. The activity threshold determines the degree of activity required to elicit a pacing rate response, whereas the rate response setting determines the rate attained. Rates of 140 bpm were rarely achieved, despite vigorous exercise. The sensor responds rapidly to activity, not to physiologic demand; to increase in speed, not grade. Four patients performed repeated limited treadmill tests to determine their optimum program setting, with symptomatic status and the healthy volunteer sinus response as guides. These results, and those from the external Activitrax unit, suggest that LOW 6 and MEDIUM 6–10 settings will prove optimum for most patients.
QT Sensing Rate Responsive Pacing and Myocardial Infarction:
Authors: EDELSTAM CECILIA , HEDMAN ANDERS , NORDLANDER ROLF , PEHRSSON S. KENNETH
Published: July 2006

A 65‐year‐old man, treated with the QT sensing rate responsive pacemaker required to manage high degree AV block, sustained a transmural inferior wall myocardial infarction 6 months after the pacemaker implant. The rate response of the pacemaker during the acute phase of the infarction was physiological as evidenced by increased pacing rate during pain and with the gradual decrease in rate during the first postinfarction days. The underlying mechanisms are discussed.
Problems of Sensing Tachyarrhythmias by an Antitachycardia Pacemaker (Symbios 7008)
Authors: NÜRNBERG MICHAEL , BIBER BRIGITTE , FROHNER KLAUS , RABITSCH CHRISTIAN , STEINBACH KONRAD
Published: July 2006

Atrial burst pacing is an effective method of terminating supraventricular tachycardia. In the patient presented in this report, a Symbios 7008 pacemaker (Medtronic Inc., Minneapolis, MN, USA) was implanted for two reasons: (1) severe AV conduction defect (AH, 230 msec; HV, 150 msec) and bifascicular block following anterior myocardial infarction; and (2) paroxysmal atrial flutter. The conduction defect ruled out programming other than atrial burst in DDD mode. Activation of burst pacing required appropriate programming of the “tachycardia detection window” on the basis of the cycle length of the flutter waves. In the case reviewed, episodes of atrial flutter with variable cycle lengths of 230 to 280 msec necessitated reprogramming of the AV interval, the refractory period, and the upper rate interval. The use of an antitachycardia device in automatic mode may be limited by variations in tachycardia cycle length.
Reversible Congestive Cardiomyopathy Due to Chronic Ventricular Tachycardia
Authors: RAKOVEC PETER , LAJOVIC JARO , DOLENC MAJA
Published: July 2006

A patient with congestive cardiomyopathy, induced by ventricular tachycardia, is presented. The patient had chronic ventricular tachycardia, which persisted 4 months and was eventually successfully treated by an antitachycardia pacemaker. A severe left ventricular dysfuncion persisted after treatment for some days and then gradually resolved. After 3 months the indices of left ventricular function returned to normal values. The tachycardia‐induced ventricular dysfunction seems to be a reversible disorder.
Comparison of Ventricular Refractory Periods Determined by Incremental and Decremental Scanning of an Extrastimulus
Authors: MORADY FRED , KADISH ALAN H. , KUSHNER JEFFREY A. , TOIVONEN LAURI K. , SCHMALTZ STEPHEN
Published: July 2006

This study compared the ventricular effective refractory periods measured by scanning diastole with an extrastimulus in incremental and decrementaJ steps of 5 msec. The subjects of the study were 80 patients undergoing a clinically indicated electrophysiological test. Eight beat basic drive trains at a cycle length of 600 msec and an intertrain pause of 4 seconds were used to measure the ventricular effective refractory period (VERP). In the incremetal method, the extrastimulus initially was positioned at a coupling interval shorter than the VERP and the coupling interval then was progressively increased until ventricular capture occurred. In the decremental method, the initial extrastimulus coupling interval was longer than the VERP and the coupling interval was progressively shortened until ventricular capture was lost. In 50 subjects, the mean VERP determined by the incremental method, 252 ± 18 (± standard deviation), was significantly longer than the mean VERP determined in the same patients by the decremental method, 248 ± 18 msec (P < 0.0001). In ten subjects, a subthreshold stimulus (S') positioned 10 msec earlier than the VERP had an inhibitory effect that lengthened the VERP by an average of 7 msec; however, when S' was positioned after the seventh beat of an eight heat drive train, no inhibitory effect could be demonstrated. In 20 subjects, VERP's were determined by the incremental and decremental methods using intertrain pauses of 1, 4, 8, 12, and 20 seconds. The mean VERP measured by the incremental method was significantly less than the mean VERP measured by the decremental method when the intertrain pause was 1,4, or 8 seconds, but not when the pause was 12 or 20 seconds. The results of this study demonstrate that incremental scanning of an extrastimulus with eight beat basic drive trains yields a longer VERP than when the extrastimulus is scanned in decremental fashion. The discrepancy between the two methods is not attributable to inhibition by noncapturing extrastimuli in the incremental method, but rather to a decrease in the VERP caused by an effect of extrastimuli that capture the ventricle in the decremental method. Therefore, when a conventional eight beat driye train and 4 second intertrain pause are used to measure ventricular refractoriness, incremental scanning of an extrastimulus yields a more accurate VERP than does decremental scanning.
Electrocardiographic Manifestations of a Dual‐Chamber, Rate‐Modulated (DDDR) Pacemaker
Authors: HAYES DAVID L. , HIGANO STUART T. , EISINGER GEORGE
Published: July 2006

Dual‐chamber, rate‐moduiated pacing (DDDR) has only recently been made available. During exercise, the pacemaker is capable of tracking not only the patient's intrinsic P wave but also the AV sequential sensor‐indicated rate response, which depends on the programmed variables of the specific sensor in the DDDR pulse generator. Programmed options thaf affect the operation of a rate‐modulated DDDR device are slope, threshold, reaction time, and recovery time. In addition, one is required to program a base or minimum pacing rate and a maximum tracking rate, as in any DDD device, as well as a maximum sensor rate. It is essential to know and understand all these programmed options if one is to correctly interpret electrocardiograms from a DDDR pacemaker. Interpreting the electrocardiograms also requires an understanding of the sensor‐indicated rate of the pacemaker at any given level of exercise, which is determined by the options previously listed and the interaction between the sensor‐indicated rate and the patient's intrinsic atrial and ventricular activity. This paper presents electrocardiograms typical of a new DDDR pacemaker undergoing clinical investigation.
High Frequency Electrocardiography of Three Orthogonal Leads in Dogs During a Coronary Artery Occlusion
Authors: ABBOUD SHIMON , SMITH JOSEPH M. , SHARGORODSKY BORIS , LANIADO SHLOMO , SADEH DROR , COHEN RICHARD J.
Published: July 2006

The ability to detect cardiac ischemia in dogs was studied using high frequency electrocardiography and signal averaging technique. Ischemia was induced via a balloon occluding cuff placed around the left anterior descending coronary artery. Three surface orthogonal bipolar leads (X, Y, and Z) were recorded prior to inflation of the occluding cuff. The cuff was then inflated, causing a complete occlusion of the coronary artery. The surface electrocardiogram was recorded before and during ligation and during reperfusion. The recorded waveforms were divided info sequential 10–15 second segments representing diferent stages of the ischemic state and were aligned using cross‐correlation scheme, averaged and band pass filtered between 150–250 Hz. Analysis of the filtered high frequency QRS complexes revealed that coronary ligation was accompanied by changes in waveform morphology including the appearance of zones of reduced amplitude. In seven out of ten experiments reduced amplitude zones were absent before the ligation, present during the occlusion and absent following reperfusion. In two experiments, reduced amplitude zones that were present prior to ligation became wider during occlusion. In one experiment no reduced amplitude zone was present during any stage of the experiment. Such zones may represent slow conduction in regions of the heart rendered ischemia during coronary Iigation. Therefore, the morphology of the high frequency QRS complex, as determined by analysis of the signal averaged electrocardiogram, may provide useful information regarding the presence of myocardial ischemia.
Ventricular and Dual Chamber Pacing for Treatment of Carotid Sinus Syndrome
Authors: BRIGNOLE MICHELE , SARTORE BRUNO , BARRA MAURO , MENOZZI CARLO , LOLLI GINO
Published: July 2006

Thirty‐nine consecutive patients with recurrent syncope and either cardioinhibitory or mixed type carotid sinus syndrome were studied to determine the efficacy of ventricular (VVI) pacing in 16, and dual chamber (DDD/DVI) in 23 patients. Only those patients affected by the isolated vasodepressor form were excluded. Follow‐up lasted 12 ± 5 months. Symptoms were totally eliminated in 67% of patients and ameliorated with persistence of minor symptoms in 33%. All patients underwent an initial 2‐month follow‐up in the VVI mode. Evaluation of the 19 patients who remained symptomatic and the 20 who became asymptomatic with VVI pacing demonstrated that factors observed prior to pacemaker implant were related to failure of the VVI mode. These included symptomatic pacemaker effect (42% vs 0%), mixed carotid sinus syndrome (95% vs 65%), orthostatic hypotension (47% vs 15%), or ventriculoatrial conduction (68% vs 38%). In the 23 patients with dual chamber pacing, random 2 month comparisons were performed between VVI and DVI/DDD pacing. The dual chamber mode was preferred by 14 patients, none preferred the VVI mode and nine noted no difference. Comparison of the two groups found that the factors linked to DVI/DDD preference were symptomatic pacemaker effect (50% vs 0%), ventriculoatrial conduction (78% vs 44%), or orthostatic hypotension (50% vs 11 %). VVI pacing is efficacious in a high proportion of patients affected by cardioinhibitory or mixed carotid sinus syndrome. The identification of causes of VVI pacing failure allows determination of those who will benefit from VVI pacing and those who should have DVI/DDD. VVI pacing is suggested for the cardioinhihitory type with no symptomatic pacemaker effect and for the mixed type with no symptomatic pacemaker effect or orthostatic hypotension or ventriculoatrial conduction. Dual chamber pacing should be used in all other instances.
Electrophysiological Demonstration of Anterograde Concealed Conduction in Accessory Atrioventricular Pathways Capable Only of Retrograde Conduction
Authors: SUZUKI FUMIO , KAWARA TOKUHIRO , TANAKA KAZUSHI , HARADA TOMO‐O , ENDOH TAKESHI , KANAZAWA YOSHIKI , OKISHIGE KAORU , HIRAO KENZO , HIEJIMA KAZUMASA
Published: July 2006

Anterograde concealed conduction into the concealed accessory atrioventricular (AV) pathway has been postulated to be one of the factors preventing the reciprocating process via the accessory pathway in patients with the concealed Wolff‐Parkinson‐White(WPW) syndrome but its presence has not been documented. To demonstrate the occurrence of anterograde concealment, 12 patients with the concealed WPW syndrome were selected for study. A pacing protocol was designed in which the retrograde conduction of the ventricular extrastimulus over the accessory pathway was assessed during ventricular pacing aione (conventional method) and during the AV simultaneous pacing (simultaneous method); the results were then compared. When the high right atrium was simultaneously paced, the effective refractory period of the concealed accessory pathway shortened as compared with the conventional method in five of 12 patients (from 341.7 ± 110.8 to 312.5 ± 108.2 msec, n = 12), whereas, it decreased in all patients studied when the coronary sinus near the accessory pathway was simultaneously paced (from 375.7 ± 135.0 to 287. ± 116.1 msec, n = 7). These results demonstrate that the AV simultaneous pacing frequently shortens the refractoriness of the concealed accessory AV pathway and such facilitation seems to he well explained by the probable anterograde concealment in it and peeling back of the refractory barrier.