Delayed cure despite early recurrence after pulmonary vein isolation for atrial fibrillation.
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Adult↗
Biomedical subjects
John P Bourke
Publications and source records attributed to John P Bourke.
Dynamic alterations in right atrial activation during atrial fibrillation.
Atrial fibrillation (AF) is usually considered to be a disorganized rhythm. However, several reports have described areas of organized right atrial (RA) activation during AF. We describe a patient with focal paroxysmal AF with a consistent pattern of organized RA activity despite typically disorganized left atrial activity. The sequence of RA activation varied, depending on which pulmonary vein foci initiated the AF.
Atrial Fibrillation↗
Standardized stimulation protocol to predict the long-term success of radiofrequency ablation of postinfarction ventricular tachycardia.
BACKGROUND: The ability to predict the success of radiofrequency ablation (RFA) is an essential step in the management of ventricular tachycardia (VT) in patients with ischemic heart disease. METHODS: This study tested a standardized programmed stimulation protocol and pre-specified definitions of procedural outcome. Consecutive patients referred for RFA of delayed post infarction VT were enrolled. Programmed stimulation was performed at the beginning and the end of an RFA procedure, and consisted of an 8 beat drive followed by up to 5 extrastimuli. Immediate success was defined as no inducible monomorphic VT, and a modified result was defined as the inducibility of VT with > 2 extrastimuli beyond those required at baseline. Procedural failure was defined when these criteria were not met. Recurrences of sustained VT and arrhythmic deaths were monitored during long-term follow-up. RESULTS: The study enrolled 112 patients. Immediate procedural success was achieved in 38%, a modified result in 34%, and procedural failure in 28% of patients. During a mean follow-up of 78 +/- 16 months, recurrent sustained VT was observed in 25 patients. VT recurrence was 3% (3/79) in patients with a successful or modified result, compared with 67% (22/33) in those who had undergone unsuccessful procedures (P < 0.001). CONCLUSIONS: This standardized stimulation protocol and definitions of procedural success, enabled us to predict with high accuracy a VT recurrence-free long-term follow-up. This may have implications in recommending devices or other treatments after RFA for postinfarction VT.
Adult↗
P wave morphology during spontaneous and paced pulmonary vein activity: differences between patients with atrial fibrillation and normal controls.
P wave morphology (PWM) has been used to predict the location of ectopic foci responsible for triggering atrial fibrillation (AF). With bi-atrial mapping, this study examined PWM during spontaneous ectopy and during pulmonary vein (PV) pacing, comparing the results with published algorithms in 40 AF patients and 15 controls. PWM during PV pacing is similar to spontaneous ectopy, if performed at similar coupling intervals. PWM during ectopic activity from the PVs is affected by cycle length and the presence of underlying atrial electrical and structural abnormalities. Changes in PWM during decremental pacing were observed in 5% of controls but in over 25% of persistent AF patients. The algorithms are accurate in over 90% of controls and paroxysmal AF patients with normal atria, but less than 60% in those with persistent AF or electrical or structural atrial abnormalities. The accuracy of non-invasive localization of arrhythmogenic PV is limited.
Adult↗
Atrioventricular block and problems with atrioventricular conduction.
This chapter has summarized briefly the current state of our knowledge on the incidence, etiology, presentation, investigation, and management of patients with AV block. The scope of the material covered has been widened intentionally to include a plethora of AV-conduction abnormalities because of the increases in the understanding of their clinical importance and contribution to left ventricular dysfunction. Under this heading, the critical importance of heart rate, maintenance of AV synchrony, and the sequence of ventricular activation and relaxation have been introduced and summarized briefly. The authors make a strong plea that, in the future, the reader consider AV-conduction abnormalities to be the parent topic, with the more-traditional, narrower subject of AV block forming a subunit thereof.
Aged↗
Errors in repolarization measurement using magnetocardiography.
Multichannel magnetocardiography (MCG) noninvasively measures variations in magnetic field strength from many sites at the body surface, potentially providing useful regional information about ventricular repolarization. MCGs contain features similar to ECGs, and although errors associated with repolarization measurement have been quantified for ECGs, no comparative data exists for MCGs. In this study, errors in manual measurement of repolarization interval in the MCG were determined. Sixteen MCG channels and three ECG leads were recorded simultaneously in eight healthy subjects. Each recording was displayed in a random order on a computer screen, in presentations with different noise levels, time display widths, and amplitude display heights. In total, manual measurement of repolarization intervals in 2,048 (eight subjects x 16 channels x eight presentations x two repeats) MCGs were made by each of four analysts. Measured repolarization intervals were reduced by 3 ms when noise was added and by a further 3 ms when this noise was doubled. Intervals were shortened by 9 ms when the time display width was doubled and by a further 10 ms when the display width was doubled again. Measurements increased by 7 ms for a doubling of amplitude display height, equivalent to a doubling of T wave height. There were also consistent differences between analysts; amounting to a greatest mean difference of 24 ms. Display characteristics, added noise, and different analysts thus affect manual repolarization interval measurements in MCG. The errors detected demonstrate the importance of a standard presentation for repolarization measurement in the MCG.
Electrocardiography↗
Paroxysmal cycle length shortening in the pulmonary veins during atrial fibrillation correlates with arrhythmogenic triggering foci in sinus rhythm.
INTRODUCTION: The focal origin of atrial fibrillation (AF) is identified by recording atrial ectopic beats or the ectopic activity that precedes AF. We hypothesized that arrhythmogenic pulmonary veins (PVs) also could be identified during persistent AF. METHODS AND RESULTS: Patients with persistent AF referred for focal ablation were enrolled prospectively. During AF, bipolar electrograms were recorded from each PV for a minimum of 120 seconds, as well as from the right atrium and coronary sinus. The cycle length of activity in each PV was measured during AF and plotted on a frequency histogram. Following cardioversion to sinus rhythm, arrhythmogenic PVs were identified from reinitiation of AF or from ectopic beats. Ten patients were enrolled and 37 PVs analyzed. During AF, 17 PVs demonstrated bimodal cycle length frequency histograms, with periods of paroxysmal short cycle length recording. Following cardioversion, 14 PVs were identified as arrhythmogenic as defined earlier. Each of these arrhythmogenic PVs showed paroxysmal short cycle length recording during AF. Sensitivity was 87%, specificity 91%, positive predictive value 87%, and negative predictive value 100%. CONCLUSION: The arrhythmogenic PVs responsible for the focal activity that triggers AF also demonstrate paroxysmal short cycle length recording during sustained AF. These results demonstrate that arrhythmogenic PVs still can be identified reliably, even during sustained AF.
Atrial Fibrillation↗
Interatrial transseptal electrical conduction: comparison of patients with atrial fibrillation and normal controls.
INTRODUCTION: This study analyzed the electrophysiologic properties of interatrial transseptal electrical conduction at Bachmann's bundle and the ostium of the coronary sinus (CS os) in response to pulmonary vein (PV) stimuli, which mimicked spontaneous ectopy. METHODS AND RESULTS: Forty patients with atrial fibrillation (AF) referred for ablation (15 persistent AF and 25 paroxysmal AF) and 15 control patients were enrolled in the study. During decremental extra-stimulus pacing from the PVs, right atrial activation was analyzed using noncontact mapping and multipolar catheters. The refractory periods and conduction times were calculated for Bachmann's bundle, CS os, and left atrium. The dispersion of refractoriness was calculated as the difference between the refractory periods of Bachmann's bundle and the CS os. The refractory period at Bachmann's bundle was 244 msec in the persistent AF group, 213 msec in the paroxysmal AF group, and 199 msec for controls. The refractory period at the CS os was 220 msec in the persistent AF group, 201 msec in the paroxysmal AF group, and 193 msec for controls. The dispersion of refractoriness was 54 msec in the persistent AF group; this was significantly greater than in paroxysmal AF at 32 msec (P < 0.05) and controls at 13 msec (P < 0.01). During decremental pacing, lengthening of conduction times at both Bachmann's bundle and the CS os were significantly greater in the persistent AF group compared with paroxysmal AF or control groups. A higher dispersion of refractoriness was associated with a higher incidence of inducible AF and a lower rate of ablation success. CONCLUSION: There are differences between the left to right interatrial electrical connections between patients with persistent AF, paroxysmal AF and controls.
Adult↗
Evolution of ventricular function during permanent pacing from either right ventricular apex or outflow tract following AV-junctional ablation for atrial fibrillation.
AIMS: To compare acute and chronic ventricular function between patients, without cardiac failure, paced at either right ventricular apex or outflow tract. METHODS: Twenty patients. 10 paced apically and 10 in the outflow tract, underwent two radionuclide ventriculograms. Eight parameters of systolic or diastolic function were compared at each assessment, as were changes within each group over time. RESULTS: No differences were identified in systolic function between pacing sites 6 weeks after pacing or 23 weeks later. Peak filling rate was lower (P=0.04) at the second assessment with outflow tract pacing. No other diastolic differences were identified. Between assessments, time to peak filling rate prolonged (P=0.04) with apical pacing, while left ventricular area reduced (P=0.04) and peak filling rate decreased (P=0.04) with outflow tract pacing. Septal motion was better preserved with outflow tract pacing. No other parameter changed over time. ECG measures were similar at 14.7 months. CONCLUSIONS: No major differences were identified in systolic function between pacing sites. Some systolic parameters were better preserved with outflow tract pacing and diastolic function deteriorated subtly over time in both groups. Right ventricular pacing adversely affects left ventricular function.
Aged↗
An essential guide to the literature.
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Journal Article↗