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Biomedical subjects

Richard J Schilling

Publications and source records attributed to Richard J Schilling.

At least 19 recordsLinked to original sources
PubMed2006

Can atrial fibrillation with a coarse electrocardiographic appearance be treated with catheter ablation of the tricuspid valve-inferior vena cava isthmus? Results of a multicentre randomised controlled trial.

OBJECTIVE: To see if strategy of ablating the tricuspid annulus-inferior vena cava isthmus (TV-IVC) is superior to electrical cardioversion to prevent recurrences in patients with coarse atrial fibrillation. DESIGN: Prospective randomised controlled multicentre study. SETTING: Four tertiary referral hospitals in the UK. PATIENTS: 57 patients with persistent coarse atrial fibrillation (irregular P waves > or =0.15 mV in > or =1 ECG lead). INTERVENTIONS: Patients were randomised to receive external cardioversion (group A, n = 30) or TV-IVC ablation +/- DC cardioversion (group B, n = 27). MAIN OUTCOME MEASURES: Cardiac rhythm, scores on quality of life and symptom questionnaires were assessed at 4, 16 and 52 weeks after the procedure. RESULTS: 20 (67%) patients in group A and 19 (70%) patients in group B were in sinus rhythm immediately after their index procedure. At 4, 16 and 52 weeks, the number of patients in sinus rhythm were 5, 3 and 2 in group A and 3, 3 and 1 in group B (p = NS). The quality of life and symptom questionnaire scores were similar in the two groups at each period of follow-up, although they were significantly better for sinus rhythm than for atrial fibrillation at each follow-up visit. CONCLUSIONS: As a first-line strategy, TV-IVC ablation offers no advantages over direct current cardioversion for the management of coarse atrial fibrillation.

Atrial Fibrillation↗
PubMed2006

Cryoablation compared with radiofrequency ablation for atrioventricular nodal re-entrant tachycardia: analysis of factors contributing to acute and follow-up outcome.

AIMS: The efficacy of transvenous Cryoablation (Cryo), for the treatment of atrioventricular nodal re-entry tachycardia (AVNRT), when compared with radiofrequency (RF) ablation, requires further investigation. METHODS AND RESULTS: We sought to compare the acute- and follow-up results of 71 cases each of Cryo and RF for AVNRT using a retrospective matched case-control study design and aimed at identifying patient and procedural factors that may predict success with each strategy. Primary failure of Cryo (thus necessitating RF at the same sitting) was seen in 11 (15.4%) cases, whereas there were two (2.8%) primary failures with RF (P<0.01). Patients in the Cryo group had significantly higher arrhythmia recurrence [14 (19.8%)] when compared with the RF group [4 (5.6%)] (P<0.01). The incidence of recurrence following Cryo was significantly higher if an echo beat was still inducible after ablation than if complete slow pathway block was achieved (7/19, vs. 4/46, P<0.001). The median number of Cryo lesions was significantly lower in patients who had recurrence compared with those who did not (1.5 vs. 3.0, P=0.02). CONCLUSION: We have observed a much higher primary failure and recurrence rate with Cryo when compared with RF for AVNRT. It may be possible to decrease this high recurrence rate by aiming to achieve complete slow pathway block and by increasing the number of Cryo lesions.

Adult↗
PubMed2006

Successful ablation of atrioventricular nodal reentry tachycardia following the atriopulmonary Fontan procedure.

Arrhythmia is a prevalent complication of the atriopulmonary Fontan procedure, most commonly macro-reentrant tachycardia within the right atrium as a consequence of long-term morphological and haemodynamic changes coupled with surgical intervention. We describe a patient with a long history of supraventricular arrhythmia following the atriopulmonary Fontan procedure identified as atrioventricular nodal reentry tachycardia at electrophysiological assessment. Despite anatomical and technical difficulties related to right atrial morphological changes and loss of the tricuspid annulus with its associated anatomical landmarks, the arrhythmia was successfully ablated using a combined antegrade and retrograde mapping approach.

Adolescent↗
PubMed2006

Validation of the noncontact mapping system in the left atrium during permanent atrial fibrillation and sinus rhythm.

OBJECTIVES: The aim of this study was to validate noncontact mapping (NCM) in the left atrium (LA) during sinus rhythm and atrial fibrillation (AF). BACKGROUND: Understanding the mechanisms of AF is crucial to the development of novel and effective treatments. Noncontact mapping records global electrical activation simultaneously and therefore has the potential to elucidate these mechanisms. METHODS: Patients underwent catheter ablation of permanent AF guided by NCM. Virtual and contact unipolar electrograms were recorded simultaneously during sinus rhythm and AF from sites spanning the LA and their morphology, amplitude, and timing were compared. The impact of distance from the array to the endocardial surface and electrogram amplitude were analyzed. RESULTS: A total of 22 patients age 52 +/- 9 (mean +/- SD) years were studied. During sinus rhythm, the median (range) morphology correlation and timing difference between contact and virtual atrial electrograms were 0.81 (0.27 to 0.98) and 4.2 (0 to 18.3) ms, respectively. These results were significantly worse than the corresponding far field individual ventricular electrograms; 0.91 (0.53 to 1.0) and 1.7 (0 to 18.3) ms (p < 0.001). For endocardial sites >40 mm from the array, the correlation was significantly worse than sites <40 mm: 0.73 (0.48 to 0.95) versus 0.87 (0.27 to 0.98) (p < 0.001). The correlation during AF was 0.72 (0.24 to 0.98), which deteriorated with increasing distance from the array. In the presence of adenosine induced atrioventricular block the correlation deteriorated 0.67 +/- 0.16 versus 0.79 +/- 0.11 (p < 0.001). CONCLUSIONS: Noncontact mapping can be performed in human LA; however, the accuracy of reconstructed electrograms is poor >40 mm from the center of the array, particularly during AF. Care must be taken interpreting isopotential maps if the entire endocardial surface of the LA is not close to the array.

Adenosine↗
PubMed2006

Radiofrequency ablation of arrhythmias guided by non-fluoroscopic catheter location: a prospective randomized trial.

AIMS: To compare the utility of non-fluoroscopic mapping systems (Carto and Ensite NavX) with that of conventional mapping in patients referred for catheter ablation of a wide variety of arrhythmias. METHODS AND RESULTS: Patients referred for catheter ablation (excluding atrial fibrillation, atypical atrial flutter, ventricular tachycardia in structural heart disease, and complete AV nodal ablation) were randomized equally to a procedure guided by Carto, Ensite NavX, or conventional mapping. A total of 145 patients were recruited (82 men, aged 49+/-16, range 18-85). In 19 patients, no ablation was performed, and in the remaining, typical atrial flutter, atrioventricular nodal re-entrant tachycardia, and atrioventricular re-entrant tachycardias [including Wolff-Parkinson-White (WPW)] accounted for 93% of ablations. Overall procedure time, immediate and short-term success, complication rate, and freedom from symptoms at follow-up were identical for all groups. NavX led to the least X-ray exposure: Navx vs. conventional, median (range): 4 (0-50) vs. 13 (2-46) min (P<0.001); NavX vs. Carto, median (range): 4 (0-50) vs. 6 (1-55) min (P=0.008). Both Carto and NavX increased disposable costs by 50% when compared with conventional (P<0.001). For typical atrial flutter, Carto and NavX reduced screening times without increasing procedure cost. If ablation was not performed, NavX was twice as expensive as Carto or conventional. CONCLUSION: Ensite NavX and Carto procedures have similar effectiveness and safety to a conventional approach; however, they both reduce X-ray exposure, with NavX producing a significantly greater effect than Carto. Although this benefit is achieved at a greater financial cost, there may be long-term benefits to catheter laboratory staff.

Arrhythmias, Cardiac↗
PubMed2006

Validation of three-dimensional cardiac image integration: use of integrated CT image into electroanatomic mapping system to perform catheter ablation of atrial fibrillation.

INTRODUCTION: Accurate visualization of the complex left atrial (LA) anatomy and the location of an ablation catheter within the chamber is important in the success and safety of ablation for atrial fibrillation (AF). We describe the integration of CT into an electroanatomic mapping (EAM) system and its validation in patients undergoing catheter ablation for AF. METHODS AND RESULTS: Thirty patients (59.2 +/- 8 years, 25 M) with paroxysmal (12) and persistent (18) AF underwent ablation using CT image integration into an electroanatomic mapping system. CT registration using the pulmonary veins as markers (landmark) was achieved with an error of 6.4 +/- 2.8 mm with repeat registration required in two patients. Registration of the CT by best fit to a electroanatomic geometry (surface) was achieved with an error of 2.3 +/- 0.4 mm. There was no significant difference in the regional LA registration error at superior (1.7 +/- 0.7 mm), inferior (2.2 +/- 1.4 mm), septal (1.7 +/- 0.8 mm), and lateral (1.7 +/- 0.7 mm, P = 0.13) sites. Cardiac rhythm at the time of CT did not have a significant effect on total or regional surface registration accuracy (mean total 2.5 +/- 0.3 in AF patients vs 2.3 +/- 0.5 in SR patients, P = 0.22). The integrated CT was used to guide the encirclement of the pulmonary veins (PV) in pairs with electrical isolation achieved by maintaining ablation along the ablation line in 58 of 60 PV pairs. Postprocedural PV angiography did not demonstrate significant stenosis. CONCLUSION: CT image integration into an EAM system was successfully performed in patients undergoing catheter ablation for AF. With a greater appreciation of the complex and variable nature of the PV and LA anatomy this new technology may improve the efficacy and safety of the procedure.

Atrial Fibrillation↗
PubMed2006

The impact of CT image integration into an electroanatomic mapping system on clinical outcomes of catheter ablation of atrial fibrillation.

BACKGROUND: A detailed appreciation of left atrial/pulmonary vein (LA/PV) anatomy may be important in improving the safety and success of catheter ablation (CA) for atrial fibrillation (AF). OBJECTIVES: The aim of this nonrandomized study was to determine the impact of computerized tomography (CT) image integration into a 3-dimensional (3D) mapping system on the clinical outcome of patients undergoing CA for AF. METHODS: Ninety-four patients (age: 56 +/- 10 years) with AF (paroxysmal 46, persistent 48) underwent wide encirclement of ipsilateral PV pairs using irrigated radiofrequency ablation with the endpoint of electrical isolation. Ablation was guided by 3D mapping alone (electroanatomic 24, noncontact 23) in 47 (3DM group) patients and by CT image integration (Cartomerge) in 47 (CT group). In persistent AF, a combination of linear ablation and targeted ablation of complex fractionated electrograms was also performed. RESULTS: Successful PV electrical isolation did not differ between the two groups. A significant reduction in fluoroscopy times was demonstrated in the CT group (49 +/- 27 minutes vs 3DM group 62 +/- 26 minutes, P = 0.03). Arrhythmia recurrence was reduced in the CT group (32% vs 51% in the 3DM group, P < 0.01). In 30 symptomatic patients (12 CT and 18 3DM), repeat procedures for AF (13 in 3DM and 5 CT, P < or = 0.10) and AT (5 in 3DM and 7 CT, P = NS) were performed. Overall success on 7-day monitor off antiarrhythmic drugs was achieved in 60% in the 3DM group when compared with 83% in the CT group (P < 0.05) at a follow-up of 25 +/- 5 weeks. CONCLUSION: CA for AF guided by CT integration was associated with reduced fluoroscopy times, arrhythmia recurrence, and increased restoration of sinus rhythm. Improved visualization of complex LA geometries might improve the safety and success of CA for AF.

Atrial Fibrillation↗
PubMed2005

Long-term results after ablation of infarct-related ventricular tachycardia.

OBJECTIVES: The purpose of this study was to assess the long-term effects of ablation of infarct-related ventricular tachycardia (VT) and the subsequent requirement for implantable cardioverter-defibrillator (ICD) therapy. BACKGROUND: The long-term consequences after initially successful catheter ablation of infarct-related VT remain unclear. METHODS: Forty patients who presented with infarct-related VT were studied using noncontact mapping to guide ablation. RESULTS: One hundred forty VTs were mapped using the noncontact mapping system, including 36 (25.7%) clinical VTs. An endocardial exit site was determined in 100% of VT circuits, diastolic endocardial activity in 77 VTs (55%), and complete circuits in 24 VTs (17.1%). Eighty-one VTs (57.9%) were targeted for ablation, of which 67 (82.7% of targeted) were successfully ablated, including 27 clinical VTs (75% of clinical). Documented recurrence of an ablated VT occurred in 7.5% of patients over 36.3 +/- 21.0 months of follow-up. Episodes of new or recurrent, nontargeted VT or ventricular fibrillation (VF) occurred in 37.5% and VT recurrence without documentation of cycle length in 5%. In patients with ICDs, mean shock frequency was reduced from 6.8 +/- 7.3 per month in the year prior to ablation to 0.05 +/- 0.12 per month after ablation, over 24.7 +/- 18.9 months of follow-up (P < .0001). CONCLUSIONS: In patients with infarct-related VT, noncontact mapping-guided VT ablation is associated with a high procedural success rate, and VT recurrence necessitating ICD therapy delivery is significantly reduced. However, only 42.5% of patients remain free from VT/VF 3 years after ablation. Catheter ablation for infarct-related VT is indicated as an adjunctive therapy in patients with symptomatic VT but cannot substitute for ICDs and antiarrhythmic drugs.

Aged↗
PubMed2004

Catheter inversion: a technique to complete isthmus ablation and cure atrial flutter.

Cure of typical atrial flutter (AFL) by catheter ablation to produce bidirectional block across the tricuspid annulus-inferior vena cava isthmus (IS) is highly effective, but failures may occur. We describe a technique that may allow creation of bidirectional block where a conventional strategy has failed. AFL ablation was performed using the conventional approach with a mapping/ablation (ablation) catheter introduced via the right femoral vein (RFV) to create a line of bidirectional block across the IS. If this was not achieved after five passes of the ablation catheter from the tricuspid annulus to the inferior vena cava (IVC) a catheter inversion technique was used. This allowed stable positioning of the ablation catheter at the IVC end of the isthmus. In 11 patients, a mean of 17 (range 3 to 45) radiofrequency (RF) applications was given before the catheter inversion technique was applied. Following catheter inversion a mean of 4 (1 to 14) further RF applications achieved bidirectional isthmus block in every patient. No complications occurred. Catheter inversion provides a simple, safe, and effective means of achieving bidirectional isthmus conduction block in cases where a conventional ablation strategy might have failed.

Aged↗
PubMed2004

Electroanatomic versus fluoroscopic mapping for catheter ablation procedures: a prospective randomized study.

INTRODUCTION: The aim of this prospective randomized study was to compare the routine use of electroanatomic imaging (CARTO) with that of conventional fluoroscopically guided activation mapping (conventional) in an unselected population referred for catheter ablation. We sought to compare the two approaches with respect to procedure outcome and duration, radiation exposure, and cost. METHODS AND RESULTS: All patients undergoing catheter ablation (with the exception of complete AV nodal ablation) were prospectively randomized to either a CARTO or conventional procedure for mapping and ablation. One hundred two patients were randomized. Acute procedural success was similar with either strategy (CARTO vs conventional 43/47 vs 51/55, P > 0.5), as was procedure duration (144 [58] vs 125 [48] min, P = 0.07 (mean [SD]). CARTO was associated with a substantial reduction in fluoroscopy time (9.3 [7.6] vs 28.8 [19.5] min, P < 0.001) and radiation dose (6.2 [6.1] vs 20.8 [32.7] Gray, P = 0.003). CARTO cases used fewer catheters (2.5 [0.7] vs 4.4 [1.1], P < 0.001), but catheter costs were higher (13.8 vs 9.3 units, P < 0.001, where one unit is equivalent to the cost of a nonsteerable quadripolar catheter). CONCLUSION: For all catheter ablation procedures, even when a center's "learning curve" for CARTO is included, procedure duration and outcome are similar for CARTO and conventional procedures. CARTO is associated with drastically reduced fluoroscopy time and radiation dose. Although fewer catheters are used with CARTO, catheter costs remain higher.

Adolescent↗
PubMed2003

Characterization of left atrial activation in the intact human heart.

BACKGROUND: The patterns of activation of the human left atrium (LA), how they relate to atrial myocardial architecture, and their role in arrhythmogenesis remain largely unknown. METHODS AND RESULTS: Left atrial endocardial activation was mapped in 19 patients with a percutaneous noncontact mapping system. Earliest endocardial breakthrough during sinus rhythm (SR) occurred more frequently in the septal (63%, principally posteroseptal) than anterosuperior (37%) LA and varied little with isoproterenol or high right atrial pacing rate. Regardless of site of breakthrough, LA activation was characterized in all patients by propagation around a variably complete line of functional conduction block, descending on the posterior wall from the roof, passing between the ostia of the superior and then inferior pulmonary veins (PVs) before turning septally, passing below the oval fossa, and merging further anteriorly with the septal mitral annulus. Examination of the myocardial architecture in 10 normal adult postmortem hearts revealed an abrupt change in subendocardial fiber orientation along a line following the same course. During episodes of focal initiation of atrial fibrillation (AF), interaction was observed between wavefronts entering the LA from PVs and this functional line of conduction block that resulted in LA macroreentry or formation of daughter wavefronts. CONCLUSIONS: The LA endocardium has complex but characteristic patterns of activation during sinus rhythm, pacing, and AF initiation by PV ectopy that are determined largely by the functional properties of atrial musculature. These findings have important implications for both pacing and ablative strategies for the prevention of initiation of AF.

Adult↗
PubMed2002

Reuse of occluded veins during permanent pacemaker lead extraction: a new indication for femoral lead extraction.

OBJECTIVES: This study examined the utility of a novel technique for reuse of thrombosed veins when extracting permanent pacemaker leads via a femoral vein approach. BACKGROUND: Although lead extraction permanent pacemaker using a femoral approach has advantages over the subclavian approach, it cannot be used to provide access for a new lead using currently employed techniques. This is important because up to 23% of patients have occluded veins after permanent pacemaker implantation. METHODS: The pacemaker lead to be extracted was released from the generator and retaining sutures at the implantation site. The lead was then grabbed from below using a needle-eye-snare or basket. The lead was then cut short and a drag through technique performed where a guide wire was pushed into the gap between the insulation and the coil. This guide wire was then drawn into the right atrium as the lead was pulled down from below. This guide wire was then used to introduce a sheath through which a replacement lead could be inserted. RESULTS: A total of 34 consecutive patients (21 male, aged 63+/-14 years, mean+/-SD) had 57 (1.7/patient) leads extracted. Fourteen patients required implantation of a new system and were suitable for immediate lead replacement using the drag through technique. All leads were successfully extracted, with 5 partial successes (9.1% of leads). The drag-through technique was successful in all, including 4 with subclavian vein occlusion. Procedure and fluoroscopy times, including the time required for implantation of a new system, were 143+/-65 mins and 31+/-23 mins respectively. There were no complications and hospital stay was 1.6+/-1.2 days for patients undergoing the drag-through procedure. CONCLUSION: The drag-through technique can be successfully used to provide access in order to replace pacemaker leads removed using a femoral approach.

Journal Article↗
PubMed2002

Characteristics of wavefront propagation in reentrant circuits causing human ventricular tachycardia.

BACKGROUND: We investigated the relationship between wavefront curvature and slowing of conduction both within and outside the diastolic pathway of circuits causing ventricular tachycardia (VT) in the infarcted human heart. METHODS AND RESULTS: Propagation was determined around the reentrant circuits of 11 VT (cycle length, 348+/-75 ms) in 8 patients undergoing high-resolution noncontact mapping. The diastolic pathway had a mean wavefront velocity of 0.82+/-0.49 m/s and occupied 68+/-7% of VT cycle length. Significant changes (>5 degrees/mm) in trajectory of propagation occurred in 8 diastolic pathway segments (10.1+/-3 degrees/mm) in which wavefront propagation slowed to 0.41+/-0.11 m/s compared with the segments immediately preceding (0.91+/-0.16 m/s, P< 0.05) and following (1.07+/-0.33, P<0.05) the change in trajectory. At the turning points of entry (9.3+/-3.9 degrees/mm) and exit (9.0+/-4.8 degrees/mm) of the diastolic pathway propagation, velocity slowed at entry from 1.23+/-0.4 to 0.6+/-0.26 ms (P<0.001) and was more rapid at exit turning points (0.8+/-0.25 m/s) (P<0.05). There was an inverse relationship between wavefront curvature and velocity, both within and outside the diastolic pathway (r=0.46, P=0.0001), and VT cycle length correlated with total curvature multiplied by length of the diastolic pathway (P< 0.01). CONCLUSIONS: Slowing of propagation in circuits causing VT in the infarcted human heart occurs over regions of wavefront turning, with an inverse relationship between wavefront curvature and velocity, both within and outside the diastolic pathway. Conduction is slower at entry than exit turning points of the diastolic pathway but is slowest during turns within the diastolic pathway.

Aged↗
PubMed2002

Atrial fibrillation: strategies to control, combat, and cure.

Atrial fibrillation is the commonest clinical arrhythmia, is increasing in incidence and prevalence, and is associated with substantial morbidity and mortality. The arrhythmia may be paroxysmal (self-limiting), persistent (amenable to cardioversion), or permanent. Especially in its paroxysmal form, atrial fibrillation may be initiated by rapidly firing foci, generally located in the proximal pulmonary veins. Sustained atrial fibrillation is maintained by an atrial tissue substrate capable of accommodating many meandering wavelets. With continuing arrhythmia, the electrophysiological properties of the atria change and further facilitate continuing fibrillation. Treatment is aimed at prevention of thromboembolic complications, restoration and maintenance of sinus rhythm, and control of ventricular rate during atrial fibrillation. With greater understanding of the arrhythmia mechanisms, it is becoming possible to offer targeted curative treatments to more and more patients.

Aged↗