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Purpose: We measured the proportion of intravascular leads, which can be extracted by simple traction versus with newer techniques, and examined the overall safety and success rate of lead extractions., Methods: Between January 2005 and December 2007, 311 consecutive patients (mean age = 70 +/- 14 years, 79% men) underwent extractions of 250 atrial, 318 ventricular, and 22 coronary sinus leads, in the surgical facilities of two experienced medical centers, under general anesthesia, at a mean of 7.2 +/- 5.1 years (range 0.1-27.0) after lead implantation. Infection was the indication for extraction in 67.5% of cases. Complementary techniques were used when simple extraction with a locking stylet was unsuccessful., Results: Simple traction, with or without a locking stylet, allowed the complete removal in 27.0% (95% confidence interval [CI] 22.1-31.9) of patients. A mechanical sheath, laser sheath, and/or lasso catheter were used in the remaining patients. The overall extraction success rate was 89.7% (95% CI 86.3-93.1). There was one procedure-related death (0.3%; 95% CI 0.0-1.0). Among five other deaths occurring within 10 days after the procedure, four were due to septic shock. Duration of lead implantation was the strongest independent predictor of major adverse events (P = 0.002) and incomplete lead extraction (P = 0.005)., Conclusion: In contrast with simple traction, advanced techniques allowed the complete extraction of nearly 90% of leads. In experienced hands and with surgical back-up, these techniques were safe. Patients presenting with infected implanted cardiac devices suffered a high rate of major adverse despite complete extraction of the lead(s).

We report a case of cycle length dependent activation sequence in the coronary sinus catheter during assessment of mitral-pulmonary vein isthmus block. A 61-year-old patient presented with atrial tachycardia following a recent pulmonary vein isolation for paroxysmal atrial fibrillation. A perimitral macroreentrant atrial tachycardia was demonstrated during mapping. The isthmus block observed following initial ablation of the mitral-pulmonary vein appeared to be pacing cycle dependent and to our knowledge has not been previously described.

The differentiation of pulmonary vein (PV) electrograms from atrial far-field signals during PV isolation (PVI) for atrial fibrillation (AF) may be difficult. In addition, owing to highly variable PV ostial sizes, current fixed-diameter circular PV mapping catheters may not yield optimal electrograms. We evaluated an expandable, circular 15-25 mm diameter, 20-pole mapping catheter for PV mapping during sustained AF in 25 patients. After selective PV angiography to define the ostial position and size, the catheter was introduced into each PV and withdrawn to the most stable proximal position, with optimal wall contact ensured by progressive loop expansion. At each PV ostium, electrograms recorded at high resolution (HR) were compared with those recorded at a resolution similar to that of a standard 10-pole Lasso catheter. After PVI performed during ongoing AF, the presence of residual far-field potentials (FFP) under both set-ups was compared. We mapped 97 PV, including 4 pairs with common ostia. In the HR recordings, the PV potentials had greater amplitude (0.5 +/- 0.1 vs 0.3 +/- 0.1 mV, P = 0.001) and fragmentation, whereas left atrial FFP were minimized. After successful isolation of all PV, FFP were observed in 33% of left superior and 28% of left inferior PV on the HR recordings, compared to 66% and 61%, respectively under normal resolution. Catheter stability and optimal wall contact, in combination with HR electrograms can optimize circumferential PV mapping during AF and improve the discrimination of FFP postablation.

Cardiac tamponade complicating catheter ablation of atrial fibrillation (AF) occurs in approximately 1% of pulmonary vein isolation (PVI), and up to 6% of linear ablation procedures. We reviewed 348 consecutive AF ablation (including repeat) procedures over 1 year, which all included PVI, with additional linear lesions at the mitral isthmus in 73%, and cavotricuspid isthmus (CTI) in 76%. An irrigated-tip ablation catheter was used, with power limited to 25-35 W for PVI and 45-60 W for linear lesions. Tamponade occurred in seven men and three women (2.9% of the population) during the creation of linear ablation lesions. Mechanical perforations occurred in two patients, and "popping" during radiofrequency (RF) energy delivery at the mitral isthmus in six, and at the CTI in two patients. Peak RF power was significantly higher in patients with than without tamponade (53 +/- 4 W vs 48 +/- 7 W; P = 0.02), and was greater than 48 W in all cases of "popping." In the following year, RF power for linear ablation was limited to

Linear left atrial ablation is performed in combination with pulmonary vein (PV) isolation to improve the clinical results of atrial fibrillation (AF) ablation. These procedures require long procedures and fluoroscopic exposure. The aim of the present study was to evaluate the performance of a new, nonfluoroscopic, real-time, three-dimensional navigation system for linear ablation at the left atrial roof and mitral isthmus. The study included 44 patients (54 +/- 10 years of age, 5 women) with drug-refractory AF, who underwent roof line or mitral isthmus linear ablation after 4-PV isolation. In 22 patients, ablation was performed with the navigation system (test group), and in the remainders linear ablation was performed with fluoroscopic guidance alone (control group). Conduction block was achieved in 20 patients (91%) in test group, and 21 patients (95%) in the control group (ns). Use of the navigation system was associated with a shorter fluoroscopic exposure for roof line (5.6 +/- 3.0 minutes vs 8.7 +/- 5.0 minutes, P < 0.05), and a trend for mitral isthmus ablation (7.8 +/- 7.8 minutes vs 12.1 +/- 5.9 minutes). It was also associated with a trend toward shorter procedure times for roof line (15.3 +/- 8.6 minutes vs 22.9 +/- 16.8 minutes) and mitral isthmus line (20.2 +/- 15.8 minutes vs 32.0 +/- 7.6 minutes) but no difference in duration of radiofrequency delivery. There was no procedural complication. The use of this new nonfluoroscopic imaging system was associated with a shorter fluoroscopic exposure as well as a trend toward shorter duration of linear ablation procedures for AF.

RF ablation for paroxysmal atrial fibrillation (PAF) is a curative treatment, which when successful, eliminates the need to take antiarrhythmic drugs, be anticoagulated, and have recurrent physician visits or hospital admissions. The authors performed a retrospective cost comparison of RF ablation versus drug therapy for PAF. The study population consisted of 118 consecutive patients with symptomatic, drug refractory PAF who underwent 1.52 +/- 0.71 RF ablation procedures (range 1-4) for PAF. During a follow-up of 32 +/- 15 weeks, 85 (72%) patients remained free of clinical recurrence in absence of antiarrhythmic drugs. The cost of RF ablation was calculated in the year 2001 euros on the basis of resource use. The mean cost of pharmacologic treatment prior to ablation was 1,590 euros/patient per year. The initial cost of RF ablation for PAF was 4,715 euros, then 445 euros/year. After 5 years, the cost of RF ablation was below that of ongoing medical management, and continued to diverge thereafter. RF catheter ablation may be a cost-effective alternative to long-term drug therapy in patients with symptomatic, drug refractory PAF.

This report describes two patients who exhibited far-field oversensing of the P wave by the ventricular channel of a DDD biventricular pacemaker implanted for the treatment of congestive heart failure. Oversensing probably occurred secondary to slight displacement of the left ventricular lead in the coronary venous system. Long-term reliable pacing was restored by decreasing the sensitivity of the ventricular channel.

The pulmonary veins are the predominant source of ectopic activity initiating AF. The reproducibility of intrapulmonary vein activation during ectopic activity and/or initiation of multiple AF episodes was examined. Eighty-nine pulmonary veins (PVs) among 29 patients undergoing radiofrequency ablation of AF were studied with a 15- to 20-mm diameter, circumferential PV catheter equipped with ten electrodes and a deflectable shaft. Local electrograms were recorded simultaneously during sinus rhythm, ectopic activity, or AF onset, spontaneously or induced via the catheter left in a stable position. Fifty-four arrhythmogenic veins were identified, 39 showing isolated ectopy, and 8 displayed repetitive ectopy (in salvos). The earliest site of activation and the sequence of intra-PV activation during isolated ectopy was identical to that observed during consecutive ectopic complexes in 77% and variable in 23% during isolated ectopy. The earliest activity was sometimes limited to a single bipole. During repetitive ectopy and AF initiation, multiple sources and/or variable activation patterns were noted in 53% of instances, indicating the presence of multiple arrhythmogenic foci within the same PV. Simultaneous electrogram recordings with a circumferential PV catheter identified the presence of multiple arrhythmogenic foci within a single PV.

Biventricular (BV) pacing is a promising treatment of end-stage heart failure. This article describes our experience with a strictly endocardial BV pacing system in patients with severe congestive heart failure. Three women and eight men (age 65 +/- 9 years) with drug-resistant end-stage CHF underwent implantation of an endocardial BV pacing system. In the first seven patients, the left ventricular lead was placed via a combined femoral and internal jugular approach. In the last four patients, the transseptal puncture was directly performed via the right internal jugular vein with a dedicated kit. The procedure was successful in all 11 patients. The acute left ventricular and BV thresholds were 1.3 +/- 0.6 V and 2.4 +/- 1 V, respectively. The QRS duration decreased from 214 +/- 57 to 176 +/- 25 ms. A functional improvement was noted in ten patients with a decrease in mean NYHA functional class from 3.7 +/- 0.5 before, to 2.6 +/- 0.9 after system implantation. A significant decrease in pulmonary capillary wedge pressure and increase in cardiac output were measured in eight patients. During follow-up, four patients died from CHF (n = 3) or ventricular fibrillation (n = 1). Under oral anticoagulation, no thromboembolic event was observed but one transient ischemic attack occurred in one patient whose anticoagulation was interrupted. Endocardial BV pacing is technically feasible and appears safe, though further studies are needed before it is used on a longer scale.

Pulmonary vein potentials (PVPs), though obvious during ectopic activity, are frequently invisible during sinus rhythm when they need to be distinguished from left atrial (LA) potentials to perform successful ablation procedures. Thirty-six patients with paroxysmal atrial fibrillation underwent circumferential PV mapping with a circular ten-electrode catheter during sinus rhythm, and during pacing from the right atrium, proximal and distal coronary sinus (CS), and LA. Ablation was performed at the ostium of the PV, the procedural endpoint consisting of electrical disconnection of the PV from the LA. A total of 93 PVs (excluding the right inferior PV) were mapped. During sinus rhythm, distinct right PVPs were present in all instances, while they were concealed within the electrograms recorded from the left inferior and superior PV in 23 (64%) patients. Distal CS or LA appendage pacing unmasked and separated left PV from LA potentials by a mean of 19 +/- 14 ms; the LA-to-left-PV potential interval measured 36 +/- 14 ms. The number of deflections also increased from 2.1 +/- 0.7 during sinus rhythm to 3 +/- 1.4 during LA stimulation. However, in the right superior PV, pacing caused overlapping of atrial potentials with right superior PVPs. RF ablation of the left PVPs was performed during distal or LA pacing in 23 patients, while in the right superior PV it was performed during sinus rhythm eliminating all, including unmasked, left PVPs, providing proof of their PV origin. Distal CS or LA pacing is required to recognize left PVPs in approximately 2/3 of patients and facilitates RF ablation.

We performed radiofrequency catheter ablation (RFCA) in 12 consecutive patients (17-77 years) with daily, symptomatic, monomorphic ventricular ectopy (VE) (12,096 +/- 3,326 on 24-hour Holter) resistant to antiarrhythmic drugs. Nine patients had no apparent structural heart disease, 1 patient had a mild dilated cardiomyopathy, 1 patient had a treated mitral stenosis, and 1 patient had arrhythmogenic ventricular dysplasia. VE morphology was LBBB with inferior axis in 9 patients, RBBB with inferior axis in 2 patients, RBBB with superior axis in 1 patient. None of the patients had spontaneous or inducible sustained ventricular tachycardia. The VE focus was targeted with RF energy at the earliest endocardial activation site and based on a matching 12-lead ECG pace map. The VE focus was localized in the right outflow tract in 9 patients and on the left ventricle in 3 patients. RFCA was delivered with a standard 4-mm tip electrode. The ablation was initially successful in 11 patients and unsuccessful in 1 patient. All successfully ablated patients were asymptomatic and discharged without antiarrhythmic drugs. During follow-up (25 +/- 8; 17-38 months), two patients had a recurrence of symptoms, which were controlled by a previously ineffective drug. At the end of follow-up, 1,329 +/- 3198 VE were observed on Holter monitoring (P < 0.001 compared with initial values). No short- and long-term complications were observed. RFCA is a safe and effective method for treating drug-resistant symptomatic monomorphic VE in carefully selected patients. A persistent benefit without complications was obtained over a 2-year follow-up.

A patient with marked first-degree AV block and a DDDR pacemaker presented with a history of paroxysmal narrow QRS tachycardia, subsequently identified as sinus tachycardia (with a very long PR interval), causing a clinical problem similar to pacemaker syndrome because of loss of AV synchrony. The latter resulted from an excessively long postventricular atrial refractory period (PVARP) that prevented sensing of sinus P waves. The unfavorable hemodynamics caused reflex sinus tachycardia. The long PVARP was mandated by the mode switching algorithm of this particular device and was automatically set according to the selected tachycardia detection rate. The patient became asymptomatic when the mode switching function was turned off and the PVARP shortened.

RF catheter ablation is highly effective in eliminating atrioventricular nodal reentrant tachycardia by targeting the slow pathway in the posteroinferior part of Koch's triangle in the right atrium. We report here a patient in whom "slow-fast" atrioventricular nodal reentrant tachycardia was eliminated only by ablation of the slow pathway in the left atrial posteroseptal region at the level of the mitral annulus after unsuccessful attempts at the traditional site on the right side.

Transcatheter radiofrequency (RF) ablation of atrial fibrillation or flutter requires the creation of linear lesions. However, conventional catheters are not predictably effective because of poor endocardial contact, and limited lesion size and penetration. The purpose of the study was to assess in the right atrium, the efficacy and safety of a new catheter designed to create long myocardial tissue lesions using RF energy. The main characteristics of this 8 Fr deflectable RF ablation catheter were: (1) a perpendicularly contacting articulated bilimb electrodes ensuring stable and firm endocardial firm contact; and (2) an irrigated planar interface. Three different electrode prototypes were tested. Fourteen anesthetized sheep weighing 61 +/- 7 kg underwent RF ablation in the right atrium using three incremental power levels (25 to 45, 50, 55 to 75 W) with the aim of creating fully transmural (FT) lesions, defined as continuous and complete epicardial and endocardial lesion imprints. The animals were euthanized 1 hour later for macroscopic and histologic examinations. Forty-three of the 80 right atrial lesions created, in smooth as well as in trabeculated areas, were FT. The percentage of FT lesions increased with the applied power from 37% with 25-45 W, to 49% with 50 W, and up to 86% for 55-75 W. In all but two cases, histologic examination showed no discontinuity between FT lesions produced by both limbs resulting in 19 coalescent linear lesions with an average size of 25 x 6 x 4 mm (length x width x depth). In situ bipolar electrograms after ablation in the FT group showed split potentials and/or a marked decrease in amplitude from 2.85 +/- 1.79 to 0.33 +/- 0.14 mV (P = 0.001) accompanied by near complete disappearance of unipolar electrograms. There was no perforation due to RF ablation. In conclusion, continuous and FT lesions can be achieved in various areas of sheep atria, including the trabecular right atrium, with a perpendicularly contacting bilimb electrode catheter. It represents a promising tool for catheter ablation of atrial fibrillation and flutter.

The aim of this study was to assess the long-term performance of a new dual chamber rate responsive pacing system based on the dynamic measurement of the peak endocardial acceleration (PEA) index of cardiac contractility. Seventy patients who participated in the Multicenter European Clinical Evaluation were studied 1 year after implantation by continuously recording the PEA and the heart rate (HR) during exercise stress testing and during 24 hours of usual activities. A complete examination of standard parameters was also performed to assess the pacing/sensing lead characteristics. Statistical comparisons were performed with the data recorded with the same protocol at 1 month after implant for each patient. A linear correlation coefficient was calculated between PEA and sinus rate when the patient showed predominant atrial tracked rhythm. There were no significant differences between PEA values measured at 1 month and 1 year (PEA = 0.41 +/- 0.26 g vs 0.45 +/- 0.29 g at rest and PEA = 1.63 +/- 0.77 g vs 1.72 +/- 0.83 g during peak exercise). The correlation coefficient remained stable (0.67 +/- 0.15 vs 0.65 +/- 0.14 during daily life and 0.74 +/- 0.14 vs 0.77 +/- 0.11 during exercise). The PEA signal detected by the sensor was reliable and stable. No long-term complications or adverse effects were observed, and the lead performance was comparable to that of a standard lead.

Unlabelled: Catheter ablation of paroxysmal atrial fibrillation using long linear lesions in the right atrium is still under investigation, and its long-term follow-up is unknown., Methods: Thirty-six men and nine women (aged 51 +/- 12 years) with symptomatic daily episodes of AF for 6 +/- 5 years despite the use of 4.7 +/- 1.5 antiarrhythmic drugs were studied between July 1994 and January 1996. Progressively longer ablation lines were performed in 3 groups of 15 consecutive patients each, using a 14-electrode catheter or a single-electrode dragging technique. Success was defined as atrial fibrillation elimination or recurrence for no longer than 6 hours over 3 months of observation. Patients who had fewer than 6 hours of atrial fibrillation per month were considered "improved." Medium- (11 +/- 4 months) and long-term (26 +/- 5 months) results were assessed clinically from a patient's diary and from Holter recordings., Results: After a follow-up of 11 months, 24 patients had a favorable result of the ablation procedure with or without additional antiarrhythmic drug therapy, representing 53% of the original cohort. After 26 +/- 5 months of follow-up, these successful results were reduced to 17 patients (37%)., Conclusions: After linear atrial ablation, a significant long-term attrition of arrhythmia-free patients was observed. This may be due to a combination of disease progression, incomplete linear block, and ineffective ablation of arrhythmogenic triggers.

Simultaneous right and left ventricular pacing was performed in a 73-year-old man with coronary artery disease end-stage congestive heart failure and a DDD pacemaker implanted for sick sinus syndrome. An endocardial LV lead was introduced transseptally after unsuccessful attempts to enter the coronary sinus. This new approach for multisite pacing offers an alternative to epicardial LV from the coronary sinus or by thoracotomy.

We evaluated the effect of atrial overdrive on the incidence of atrial arrhythmias (AA) in 22 patients (67 +/- 9 years, 7 women, 15 men) with Chorus 6234 DDD pacemakers. Atrial overdrive was defined as a programmed paced rate 10 ppm faster than the mean ventricular rate stored for the last 24-hour period in the pacemaker memory. The protocol consisted of three phases of 1 month each. Phase I: observation after discontinuation of antiarrhythmic therapy. Phase II: arrhythmia analysis using the pacemaker memory after programming the lower rate to 55 ppm. The fallback function and histogram data were used to document the number and maximal duration of AA episodes as well as the total AA time in a month. Phase III: atrial overdrive. The mean ventricular heart rate was 65 +/- 4 beats/min before atrial overdrive versus 75 +/- 5 with atrial overdrive (P = 0.02). At the end of phase II, all patients presented with AA episodes (mean number per patient: 42 +/- 78 in one month). In phase III (with atrial overdrive), 14 (64.6%) patients had no recorded AA (group A). In the other eight patients with persistent AA episodes in phase III (group B), there was a significant reduction in the number of AA episodes (90 +/- 106 in phase II vs 38 +/- 87 in phase III; P = 0.01), their total duration (166 +/- 115 in phase II vs 92 +/- 134 hours in phase III; P = 0.03) and their maximal duration (121 +/- 103 in phase II vs 85 +/- 89 min; P = 0.04). Our short-term data suggest that atrial overdrive prevents or reduces AA episodes and demonstrate the feasibility and need of long-term studies to determine whether this benefit is sustained.

Special software allowing the memorization of 24-hour minute ventilation can be loaded into the memory of the Chorus RM, a DDDR pacemaker driven by minute ventilation. This feature was tested in the postimplant period in 13 patients. Measurements of minute ventilation, respiratory rate, and respiratory amplitude were analyzed according to prospectively defined diurnal and nocturnal time periods. Minute ventilation decreased by 39% (P < 0.001) from the diurnal to the nocturnal phase, while respiratory rate and amplitude decreased by 18% and 28%, respectively (P < 0.001 each). Thus, minute ventilation allowed discrimination between sleep and waking hours. This information could be utilized to modulate the backup rate of the pacemaker.

To optimize programming of rate adaptive pacemakers (RAPs), we explored a new mathematical method to assess the performance of RAPs during daily-life tests, using customized Windows-based software. By stepwise discriminant analysis and linear regression, this method allows calculation of the acceleration and deceleration capacity of pacemakers and their general behavior during effort and recovery phases. Twenty-three patients (10 females and 13 males; 68 +/- 8 years) with chronic atrial fibrillation and a slow ventricular response were evaluated. They randomly received an accelerometer-controlled VVIR Dash Intermedics pacemaker (10 patients) or a vibration piezoelectric-controlled VVIR Sensolog III Siemens pacemaker (13 patients). All patients underwent the same test protocol: 6 minutes walking, 1.5 minutes climbing stairs, 1.5 minutes descending stairs, and 0.5 minutes sit-ups. By definition, the pacemaker responsiveness slope was programmed so that the heart rate response of paced patients during the walking test corresponded best to that of healthy controls. The slope was left unchanged for the other tests. We considered four scores: an acceleration score (EA score), an effort rate score (ER score), a deceleration score (RD score), and a recovery rate score (RR score). Scores ranged from -10 (hypochronotropic behavior of the pacemaker) to +10 (hyperchronotropic behavior), based on daily-life tests of 15 healthy controls (7 females and 8 males, 65 +/- 9 years). A score of 0 represented exact concordance with healthy controls. During stair descent, the Sensolog III produced excessive acceleration (EA score = +2.9 +/- 1.1) compared to: (1) stair climbing (EA score = -4.0 +/- 1.9; P = 0.01, with the same pacemakers); and (2) the Dash (+1.8 +/- 1.9; P = 0.04) and healthy controls (P = 0.02). The sit-up tests revealed a hypochronotropic response of both pacemakers compared to healthy controls, with a larger difference for the Sensolog III (EA score = -2.0 +/- 5.8; P = 0.04; RD score = -6.8 +/- 3.8' P = 0.02). We conclude that activity-driven pacemakers can accommodate brief activities, except for isovolumetric exercise such as sit-ups. During daily activities, accelerometer-driven pacemakers seem to provide a heart rate resoibse closer to that of healthy controls. Our new mathematical analysis is a simple and reproducible method for evaluating and quantifying the efficacy of any sensor-driven pacemaker.

Atrioventricular junctional reentrant tachycardia (AVJRT) is the most common form of paroxysmal regular supraventricular tachycardia. In patients with disabling, drug refractory AVJRT, catheter ablation has evolved rapidly from a last-resort treatment in the form of interruption of atrioventricular (AV) conduction to selective modification of AV nodal function as an ideal treatment. This article will focus on the frequently unappreciated electrophysiological activities recordable in man in Koch's triangle during ablation of the so-called slow pathway.

Unlabelled: Previous experimental data suggest that atrial activity is homogeneously distributed during paroxysmal atrial fibrillation (AFib). Little is known about this in human paroxysmal AFib., Methods: Twenty-five men and two women (mean age 49 +/- 11 years; five with structural heart disease) with paroxysmal AFib for a mean 5 +/- 6.2 years despite the use of a mean of 3.6 +/- 1.7 antiarrhythmic drugs underwent atrial mapping. The right atrium was divided into four regions: posterior (intercaval), lateral, anterior, and septal. A 14-pole catheter was positioned to assess complex electrical activity defined as the duration of continuous electrical activity or electrograms with FF intervals < 100 ms for 60 seconds (expressed as percentage of time). In addition, the left atrium (divided into three regions: posterior, anterior, and septal) was explored in 12 patients with a multipolar catheter., Results: The complex electrical activity time between all the regions explored was significantly different. In the right atrium, the septal (74% +/- 32%; P = 0.02) and the posterior (63% +/- 32%; P = 0.04) areas were significantly more disorganized than the lateral (22% +/-23%) and anterior (21% +/- 26%) regions. In the left atrium, complex electrical activity was predominant and widely distributed (posterior: 87% +/- 11%; septal: 65% +/- 27%) except in the appendage area (anterior region: 18% +/- 14%)., Conclusions: Quantitative assessment of complex electrical activity in both atria in humans shows heterogeneous temporal and spatial distribution. This may have implications for guiding catheter ablation of AFib.

Survival after closed-chest ablation of His bundle with DC shock for supraventricular arrhythmias was analyzed for a 10-year period (May 1982-December 1992) with 317 consecutive patients (167 males, 150 females; mean age 66 years; range 33-93 years). Of these, 54 patients died (17.3%) and 5 were lost to follow-up. The mean age at ablation was 70.3 +/- 8.3 years with a range of 49-93 years. Of those who died, the mean survival was 30.5 +/- 28.6 months with a range of 36 hours to 120 months; the diagnosis of heart disease was: hypertension (n = 14), cardiomyopathy (n = 8), ischemic (n = 7), valvular (n = 6), cor pulmonale (n = 3), valvular and ischemic (n = 2), hypertension and ischemic (n = 1), miscellaneous (n = 3), and none (n = 10). Of the patients who died after ablation, the arrhythmias at the time of the ablation were atrial fibrillation (AF; n = 33), sick sinus syndrome (n = 5), atrial flutter (AFL; n = 4), paroxysmal AV junctional tachycardia (PAVJT; n = 4), AF + AFL (n = 4), atrial tachycardia (n = 2), PAVJT + AFL (n = 1), and AF +AFL + atrial tachycardia (n = 1). Death was sudden in 13 patients (25%), due to heart failure in 10 (19.2%), myocardial infarction in 4 (7.7%), stroke in 4 (7.7%), aortic vascular accident in 3 (5.8%), miscellaneous in 18 (34.6%), and undetermined in 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Pervenous atrioventricular sequential demand pacemakers (AVSDPs) were implanted in 18 patients using an atrial electrode positioned in the right atrial appendage and a ventricular electrode positioned at the apex of the right ventricle. The indications included 13 patients with the sick sinus syndrome (72%), five of whom had the tachycardia-bradycardia syndrome, three with paroxysmal supraventricular tachycardia, one with cardiomyopathy and one with carotid sinus syncope. The follow-up ranged from 6 to 38 months, with a mean of 19.4 months (a total of 350 pacing months). Seventeen patients (94%) are asymptomatic. One patient had persistent episodes of paroxysmal supraventricular tachycardia. In the remaining patients with tachyarrhythmia, pacing alone (three patients) or in combination with antiarrhythmic drugs (four patients) controlled the tachyarrhythmia. There was one displacement of the atrial electrode (5.5%). Extrusion of the pacer occurred in three patients. It is concluded from this experience that AV sequential pacing is an effective technique and may be useful in patients with sick sinus syndrome, in patients with tachyarrhythmia and/or patients with poor myocardial function. However, continued research is needed to prolong battery life and to reduce the size of the pacemaker.