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Biomedical subjects

Kenneth A Ellenbogen

Publications and source records attributed to Kenneth A Ellenbogen.

At least 73 records · Page 4Linked to original sources
PubMed2004

Effects of ventricular rate regularization pacing on quality of life and symptoms in patients with atrial fibrillation (Atrial fibrillation symptoms mediated by pacing to mean rates [AF SYMPTOMS study]).

The aim of this study was to investigate the effect of the Ventricular Response Pacing (VRP) algorithm, which regularizes ventricular rate during atrial fibrillation (AF), on symptoms, quality of life, and functional capacity. VRP regularizes the ventricular rate during AF without increasing the mean ventricular rate, thereby reducing the severity of AF-related symptoms in patients with persistent AF. However, VRP did not improve general quality of life (Medical Outcomes Study 36-item Short-Form General Health Survey), the performance of routine activities (Duke Activity Status Index), or functional capacity (hall walk) in patients with AF.

Aged↗
PubMed2004

High incidence of pacemaker syndrome in patients with sinus node dysfunction treated with ventricular-based pacing in the Mode Selection Trial (MOST).

OBJECTIVES: We evaluated the incidence, predictors, and treatment of pacemaker syndrome in patients with sinus node dysfunction treated with ventricular-based (VVIR) pacing in the Mode Selection Trial (MOST). BACKGROUND: Pacemaker syndrome, or intolerance to VVIR pacing, consists of cardiovascular signs and symptoms induced by VVIR pacing. METHODS: The definition of pacemaker syndrome required that a patient with single-chamber VVIR pacing develop either congestive signs and symptoms associated with retrograde conduction during VVIR pacing or a >or=20 mm Hg reduction of systolic blood pressure during VVIR pacing, associated with reproducible symptoms of weakness, lightheadedness, or syncope. RESULTS: Of 996 patients randomized to VVIR pacing, 182 (18.3%) met criteria for pacemaker syndrome in follow-up. Pacemaker syndrome occurred early in most patients (13.8% at 6 months, 16.0% at 1 year, increasing to 19.7% at 4 years). Baseline univariate predictors of pacemaker syndrome included a lower sinus rate and higher programmed pacemaker rate. Previous heart failure, ejection fraction, and drop in systolic blood pressure with VVIR pacing at implantation did not predict the development of pacemaker syndrome. Post-implantation predictors of pacemaker syndrome were a higher percentage of paced beats, higher programmed low rate, and slower underlying spontaneous sinus rate. Quality of life decreased at the time of diagnosis of pacemaker syndrome and improved with reprogramming to atrial-based pacing. CONCLUSIONS: Severe pacemaker syndrome developed in nearly 20% of VVIR-paced patients and improved with reprogramming to the dual-chamber pacing mode. Because prediction of pacemaker syndrome is difficult, the only way to prevent pacemaker syndrome is to implant atrial-based pacemakers in all patients.

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PubMed2004

A comparison of pulmonary vein ostial anatomy by computerized tomography, echocardiography, and venography in patients with atrial fibrillation having radiofrequency catheter ablation.

Accurate assessment of pulmonary vein anatomy is important to procedures that isolate these structures in patients with atrial fibrillation. Various modalities of pulmonary vein (PV) imaging are employed in clinical practice; however, the consistency of findings among the different modalities is unknown. The purpose of this study is to compare PV ostial anatomy by 4 common imaging techniques. Twenty-four patients undergoing catheter-based PV isolation procedures for atrial fibrillation had their PV ostial anatomy determined by cardiac computerized tomography (CT) and transesophageal echocardiography (TEE) before ablation and by intracardiac echocardiography (ICE) and venography during the ablation procedure. The number and maximal dimension of the PV ostia were determined by each imaging modality. In the 24 patients, 98 PV ostia were visualized by CT, 93 by ICE, 81 by TEE, and 71 by venography. The average ostial diameters were similar between CT (1.45 +/- 0.29 cm) and ICE (1.51 +/- 0.22 cm, p = 0.066). Compared with CT or ICE, the ostial diameters were larger with venography (1.67 +/- 0.32 cm) and smaller with TEE (1.16 +/- 0.28 cm, all p <0.001). PV ostial diameters as determined by ICE were significantly correlated with CT measurements (r = 0.57, p <0.001) and venography (r = 0.52, p <0.001). Venography measures of PV diameter were correlated with measures by CT (r = 0.33, p = 0.03). TEE measures were not correlated with any other modality (all p >/=0.43). CT identifies the greatest number of PV ostia followed by ICE. Venography overestimates and TEE underestimates ostial diameters compared with CT or ICE. The PV ostial dimensions obtained by ICE, CT, and venography are all significantly correlated.

Atrial Fibrillation↗
PubMed2004

Comparison of perception of health status by physicians, nurses, and patients in the Dual-chamber And VVI Implantable Defibrillator (DAVID) trial.

Previous studies have shown a poor correlation between health and quality-of-life assessments by patients, physicians, and nurses. Some have argued that patients are treated impersonally in clinical trials. Because one would expect that patient care would be compromised if this were the case, we used the Dual-chamber And VVI Implantable Defibrillator (DAVID) clinical trial setting to see if these assertions truly reflect the assessments of quality of life by health care professionals. Physicians, nurses, and patients in the DAVID trial had concordant assessments of the patients' perception of health status. The findings dispel assertions that patient concerns are not reliably assessed.

Clinical Trials as Topic↗
PubMed2004

Recurrence of left atrium-pulmonary vein conduction following successful disconnection in asymptomatic patients.

BACKGROUND: The clinical significance of conduction recurrences in isolated pulmonary veins of patients with atrial fibrillation is not established. METHODS: Twenty-two patients with paoxysmal atrial fibrillation underwent successful pulmonary vein isolation. Six months after the procedure, 14 patients were free of atrial fibrillation. Two of these patients were subjected to repeat mapping of the left superior pulmonary vein. RESULTS: There was recurrence of pulmonary vein to left atrium conduction despite complete lack of symptoms or evidence of recurrent atrial fibrillation. CONCLUSION: Successful pulmonary vein isolation with abolition of paroxysmal atrial fibrillation does not confer permanent disconnection of the pulmonary vein musculature from the left atrium.

Atrial Fibrillation↗
PubMed2004

Identification of preferential sites of parasympathetic input to the atrioventricular node in man.

OBJECTIVES: The effects of subthreshold stimulation performed at various sites in the perinodal and posteroseptal space on atrioventricular (AV) nodal conduction were investigated. BACKGROUND: The identification of specific or preferential sites of parasympathetic innervation to the AV node is suggested by observations made in both the animal and clinical laboratories. Pathologic studies of the parasympathetic innervation to the AV node show it is made up of serpiginous fibers traveling at highly specific sites within the myocardium endocardially towards the compact AV node. METHODS: We utilized endocardial subthreshold stimulation to selectively identify and characterize AV nodal inputs. Fourteen patients (age: 56 +/- 4 years) undergoing electrophysiologic testing with or without radiofrequency ablation for supraventricular tachycardia were studied. A steerable quadripolar catheter was positioned in 3 to 9 locations in the region between the site recording the His bundle electrogram and the coronary sinus (CS) os under flouroscopic and electroanatomic guidance. We mapped anterosuperior sites at or near sites with His potential recordings, and up to 2 mm inferior to the His bundle recording, posteroseptal sites included the CS os and sites along the posterior, superior, and inferior border of the CS. Atrial pacing was performed at a cycle length 50 ms longer than Wenckebach cycle length. Subthreshold stimulation was applied at a frequency of 10 Hz and 20 Hz delivered to the distal electrode pair. AH and HV intervals were recorded before and during subthreshold stimulation. AH prolongation was defined as a reproducible increase in AH interval by >10 ms from a stable baseline AH interval. RESULTS: Eight of 14 patients demonstrated prolongation of AV conduction at a mean of 1.75 +/- 0.2 sites. Mean AH prolongation was 56.4 +/- 13.0 ms (p = 0.02) from baseline. AH prolongation was achieved 15.4 +/- 1.8 mm below the His bundle recording in 7 patients, at the site of the His bundle recording in 3 patients, and along the posterior CS os border in 3 patients. CONCLUSION: Subthreshold stimulation prolongs AV nodal conduction only at specific sites within the triangle of Koch, suggesting discrete parasympathetic endocardial inputs into the AV nodal region.

Adult↗
PubMed2004

Right and left inferior extensions of the atrioventricular node may represent the anatomic substrate of the slow pathway in humans.

OBJECTIVES: The purpose of this study was to investigate the electrophysiologic characteristics of the inferior extensions of the human atrioventricular (AV) node and their possible relationship to slow pathway conduction. BACKGROUND: The human heart contains right and left inferior extensions of the AV node that relate to right and left atrial inputs. METHODS: Fourteen patients admitted for catheter ablation of left-sided accessory pathways were studied. Atrial pacing was performed from multiple sites in both atria, and simultaneous His-bundle recordings from right and left sides of the septum were made. RESULTS: Significant differences of A-H and stimulus to His (St-H) intervals with pacing at various sites were found. St-H intervals were similar during constant pacing from the low right atrium or the left inferoparaseptal area (112 +/- 28 ms vs 112 +/- 26 ms, P = .8, for right His recordings and 114 +/- 23 ms vs 111 +/- 25 ms, P = .9, for left His recordings). At maximum decrement, there were significantly shorter St-H intervals during left inferoparaseptal pacing compared to low right atrial pacing (201 +/- 24 ms vs 218 +/- 44 ms, P = .02, for right His recordings, and 200 +/- 24 ms vs 219 +/- 41 ms, P = .009, for left His recordings). Differences on right His recordings between St-H intervals at maximum decrement and at constant pacing from the low right atrium were significantly higher than corresponding differences on left His recordings during pacing from the left inferoparaseptal area (P = .035). CONCLUSIONS: Our findings support the concept that the right and left inferior extensions of the human AV node may represent the anatomic substrate of the slow pathway as defined electrophysiologically.

Adult↗
PubMed2004

Device therapy for atrial fibrillation.

Currently, there are more therapeutic options available for AF patients with recurrent symptomatic AF episodes. The studies on the role of device therapy for AF have been promising thus far, but they have not achieved any of the goals of AF management. Based on large randomized clinical trials, patients with SSS should receive atrial-based pacing devices. Moderate sized randomized studies have shown minimal benefit of multi-site pacing in AF prevention, even when combined with antiarrhythmic agents. Alternative site pacing such as septal pacing (high or low), however, may be more advantageous, as it achieves similar results in terms of AF reduction with less hardware. The role of ATP in AF prevention is still in its infancy and will need further studies to determine its role in conjunction with antiarrhythmic agents. Furthermore, the role of radiofrequency ablation of pulmonary veins and other sites of AF initiation has been evolving and may be offered to more patients in the future. This approach may be more acceptable to patients and may gain wider acceptance for some groups of AF patients rather than device therapy. In any event, there is still a large role for pacemaker therapy in the management of AF, especially in patients who cannot benefit from curative ablation or surgery procedures, or patients who have failed these procedures, and particularly elderly patients who typically do not undergo these procedures. Based on current understanding, careful selection of pacing sites and pacing algorithms may help in reducing AF episodes in patients receiving devices.

Atrial Fibrillation↗
PubMed2004

Use of a non-fluoroscopic catheter navigation system for pulmonary vein isolation.

INTRODUCTION: Pulmonary vein (PV) isolation is commonly performed by using separate mapping and ablating catheters. Steering the ablation catheter to the target electrodes on the mapping catheter can be difficult and time consuming under fluoroscopic guidance. We investigated the use of a non-fluoroscopic catheter navigation system to facilitate radiofrequency pulmonary vein isolation. METHODS: The LocaLisa non-fluoroscopic catheter navigation system was used during PV isolation in 21 patients. Eleven control patients underwent the procedure under fluoroscopic guidance alone. PV isolation was performed by mapping the veins with a 10 or 20 pole circular mapping catheter and ablating at targeted mapping bipoles with a separate ablation catheter. RESULTS: The electrodes of both catheters were visualized in 3 dimensional virtual space by LocaLisa. There were no clinical differences between the LocaLisa and control patients. During mapping, electrical artifacts were produced on specific mapping electrodes by contact with the ablation catheter. A blinded observer using LocaLisa correctly identified the mapping electrodes being contacted by the ablation catheter in 368 of 398 (92%) of cases. Total fluoroscopic time was reduced in the LocaLisa group (72 +/- 29 minutes) compared to the control group (102 +/- 37 minutes, p = 0.02). There were no differences between the groups in total procedure times, number of lesions given, complications or long term procedural success (all p > 0.45). CONCLUSIONS: The LocaLisa catheter navigation system accurately identifies the position of an ablation catheter relative to the target electrodes on a circular mapping catheter. The system also significantly reduces total fluoroscopic time for PV isolation.

Atrial Fibrillation↗
PubMed2004

Response of pulmonary vein potentials to burst pacing.

BACKGROUND: Pulmonary vein potentials recorded at the ostia of pulmonary veins (PV) are a useful guide for segmental isolation of the PV in patients with atrial fibrillation (AF). Even during coronary sinus pacing at 600 ms, atrial (A) and PV potentials can overlap in 50-60% of patients making the accurate identification of PV potentials very difficult. METHODS: Nineteen patients (M:F 15:4) with paroxysmal AF underwent segmental isolation of one or more PV. Coronary sinus (CS) pacing was performed at cycle lengths of 600/550/500/450/400/350/300 ms and bipolar electrograms were recorded from the 10 or 20 pole Lasso catheter placed at the atrial-PV junction in 27 pulmonary veins. Stimulus (S) to A, S-PVP and A-PVP intervals were measured during CS pacing at the different cycle lengths at sweep speed of 200 mm/sec. RESULTS: During CS pacing at 600 ms the A and PV potentials were significantly overlapped (A-PVP < or = 25 ms) in 15 of 27 (55%) veins. During pacing at 300 ms, the A and PV potentials were significantly separated (A-PVP > or = 25 ms) in 9 of the 15 veins where A and PV potentials overlapped and 21 of all 27 (78%) veins. In two patients pacing at 300 ms was associated with 2:1 conduction block from atrial to PV fascicle. CONCLUSIONS: Coronary sinus pacing at cycle length of 300 ms demonstrated better separation of A and PV potentials compared to pacing at 600 ms. This strategy is easier and less time consuming compared to extrastimuli testing. It also confirms that the electrophysiological properties of PV fascicles are different from that of the adjacent atrial musculature.

Atrial Fibrillation↗
PubMed2004

Prospective randomized study of mode switching in a clinical trial of pacemaker therapy for sinus node dysfunction.

INTRODUCTION: Atrial fibrillation (AF) is common in pacemaker patients with sinus node dysfunction (SND) and may result in rapid ventricular pacing (RVP) in the DDDR mode. Mode switching (MS) reduces RVP, but its clinical benefit in patients with SND is unknown. METHODS AND RESULTS: Two hundred two patients in the Mode Selection Trial (MOST; 2,010-patient, 6-year trial of DDDR vs VVIR pacing in SND) randomized to DDDR pacemakers with atrial high-rate episode (AHRE) storage capabilities were subrandomized to MS ON (N = 96) or MS OFF (N = 106). Cardiovascular symptoms, quality of life (QOL), reprogramming due to RVP, death, stroke, and heart failure hospitalization (HFH) were compared between groups. The treatment groups were similar with regard to AF history (59% MS ON vs 57% MS OFF). AHREs occurred in 49% patients during median follow-up of 2.2 years. Median AHRE duration (in min; MS ON 116 vs MS OFF 58, P = 0.29), frequency AHREs/week (MS ON 3.5 vs MS OFF 6.4, P = 0.23), and time spent in AHRE (min/week) (MS ON 450, MS OFF 268) were similar. Reprogramming due to any RVP during AHREs occurred more in MS OFF vs MS ON (13.2% vs 3.1%, P = 0.011) and marginally more for symptomatic RVP (8.5% vs 2.1%, P = 0.062). Cardiovascular symptoms occurred in 93.6% MS ON vs 90.2% MS OFF (P = 0.38). Median number of symptoms reported per visit was similar (MS ON 1.3 vs MS OFF 1.5, P = 0.62). Median symptom frequency/severity, summed and averaged over visits, was similar (MS ON 4.3 vs MS OFF 4.5, P = 0.74). QOL was not different between groups. Death, stroke, and HFH were not different between groups. CONCLUSION: MS reduces pacemaker reprogramming due to RVP during AHREs in a small number of patients but does not improve QOL or cardiovascular symptoms overall among patients with SND.

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PubMed2004

Ablation of superior pulmonary veins compared to ablation of all four pulmonary veins:.

INTRODUCTION: Isolation of all pulmonary veins (PV) is advocated for treatment of paroxysmal atrial fibrillation (PAF). However, the superior PVs are responsible for most AF triggers, whereas the inferior PVs carry the higher risk for ablation-induced ostial stenosis. The aim of this study was to compare a superior PV isolation approach with isolation of all PVs for treatment of PAF. METHODS AND RESULTS: Fifty-two patients with PAF were randomized to either left superior pulmonary vein (LSPV) isolation followed by additional isolation of the right superior pulmonary vein (RSPV) in case of AF recurrence (group A, n = 27) or isolation of all four PVs followed by a repeat procedure in case of recurrence (group B, n = 25). At 1-year follow-up, 11 patients (41%) in group A and 8 patients (32%) in group B had AF relapse (P = 0.55). No significant differences in AF relapse were detected between groups at 3 and 12 months (log rank = 0.36, P = 0.54) and by Cox proportional hazards model analysis (P = 0.62). Nonsignificant PV stenosis was detected in two patients from group B. Total radiofrequency energy delivery and fluoroscopy and procedure times were lower in group A: 8.9 +/- 1.4 minutes vs 25.6 +/- 3.7 minutes (P < 0.001), 22.2 +/- 6.8 minutes vs 62 +/- 10.3 minutes (P < 0.001), and 131.8 +/- 26.5 minutes vs 222.2 +/- 32.3 minutes (P < 0.001), respectively. CONCLUSION: A staged superior PVs isolation approach confers equal success rates but with reduced radiofrequency energy delivery and fluoroscopy and procedure times compared to isolation of all PVs at the initial ablation attempt.

Adult↗
PubMed2004

Myocardial ischemia and induction of sustained ventricular tachyarrhythmias: evaluation using dobutamine stress echocardiography-electrophysiologic testing.

INTRODUCTION: This study examined the relationship between dobutamine facilitation of ventricular tachyarrhythmia (VT) inducibility with programmed electrical stimulation (PES) and dobutamine stress-induced myocardial ischemia. METHODS AND RESULTS: Twenty patients with prior myocardial infarction and cardiac arrest or sustained VT but no sustained VT induced at baseline electrophysiologic testing underwent repeat PES during dobutamine infusion. Ischemia (new or worsened wall-motion abnormality) was documented by echocardiography performed in conjunction with PES. Eight patients were receiving Class I or III antiarrhythmic drugs and seven beta-blockers. Dobutamine facilitated induction of sustained VT in 16 patients (80%) and provoked ischemia in 13 patients (65%). Induction of VT was associated with ischemia in 9 patients (56%). VTs associated with ischemia were induced at higher dobutamine doses (26 +/- 11 vs 11 +/- 10 microg/kg per min, P = 0.02) than were VTs without ischemia (n = 7). Among 13 patients with provoked ischemia, 9 (69%) had VTs induced and 4 remained noninducible. The onset of ischemia occurred at the same dose as induction of VT in 5 patients and at a lower dose in 4 patients. Monomorphic VT (318 +/- 59 ms) was induced in 13 patients, of whom 8 (62%) had ischemia. The ECG morphology of VT suggested an origin in a myocardial segment that demonstrated initial viability at low doses then ischemic dysfunction at higher doses preceding VT induction in 7 (88%) of 8 patients. CONCLUSION: Dobutamine enhances inducibility of sustained VTs during PES. The temporal and anatomic association of dobutamine-induced ischemia and VT suggests that at high dobutamine doses, ischemia may contribute to ventricular arrhythmia inducibility in some patients.

Adult↗
PubMed2004

Is isolation of all four pulmonary veins necessary in patients with paroxysmal atrial fibrillation?

The upper pulmonary veins (PVs) are responsible for the majority of atrial fibrillation (AF) triggering foci, whereas the inferior PVs are more difficult to ablate and prone to postablation ostial stenosis. Most procedure failures can be attributed to incomplete isolation or recurrent PV left atrial reconnection rather than to identification of another focus. Furthermore, in certain patients AF triggers can be detected outside the PVs, and local denervation of the ganglionic plexus around the superior PV left atrial junctions following the ablation procedure may also play a role in eliminating AF. Based on these data, the authors propose that in AF patients the superior PVs should be ablated first, and in case of recurrence a second procedure should be performed for identification of PV left atrial reconnection or extrapulmonary foci and additional ablation of the inferior PVs. Such a staged approach might offer slightly lower success rates but with a significantly lower radiation exposure and procedural time and at a smaller risk of ablation induced PV stenosis.

Atrial Fibrillation↗
PubMed2003

Complications arising after implantation of DDD pacemakers: the MOST experience.

The purpose of this study was to characterize the incidence, time course, frequency, and spectrum of acute and chronic complications arising from dual-chamber pacemaker implantation. This information may serve as a benchmark when comparing complication rates for dual-chamber pacemaker implantation with those for biventricular pacemaker implantation.

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