Workload and usefulness of daily, centralized home monitoring for patients treated with CIEDs: results of the MoniC (Model Project Monitor Centre) prospective multicentre study.

AIM: Automated, daily Home Monitoring (HM) of pacemaker and implantable cardioverter-defibrillator (ICD) patients can improve patient care. Yet, HM introduction to routine clinical practice is challenged by resource allocation for regular HM data review. We tested the feasibility, safety, workload, and clinical usefulness of a centralized HM model consisting of one monitor centre and nine satellite clinics. METHODS AND RESULTS: Having no knowledge about patients' clinical data, a telemonitoring nurse (TN) and a supporting physician at the monitor centre screened and filtered HM data in 62 pacemaker and 59 ICD patients from nine satellite clinics for over 1 year. Basic screening of arrhythmic and technical events required 25.7 min (TN) and 0.7 min (physician) per working day, normalized for 100 patients monitored. Communication of relevant events to satellite clinics per email or phone required additional 4.3 min (TN) and 0.4 min (physician). Telemonitoring nurse also screened for abnormal developments in longitudinal data trends weekly for 3 months after implantation, and then monthly; one patient session lasted 4.0 ± 2.9 min. To handle transmission-gap notifications, TN needed additional 2.8 min daily. Satellite clinics received 231.3 observations from the monitor centre per 100 patients/year, which prompted 86.3 patient contacts or intensive HM screening periods by the satellite clinic itself (37.3% response rate), 51.7 extra follow-up controls (22.3%), and 30.1 clinical interventions (13.0%). CONCLUSION: Centralized HM was feasible, reliable, safe, and clinically useful. Basic screening and communication of relevant arrhythmic and technical events required a total of 30 min (TN) and 1.1 min (physician) daily per 100 patients monitored.

Comparison of non-gated vs. electrocardiogram-gated 64-detector-row computed tomography for integrated electroanatomic mapping in patients undergoing pulmonary vein isolation.

AIMS: To compare non-gated vs. electrocardiogram (ECG)-gated 64-detector-row computed tomography (MDCT) of the left atrium (LA) for integrated electroanatomic mapping (EAM) in patients with paroxysmal atrial fibrillation (AF). METHODS AND RESULTS: Twenty-nine consecutive patients with paroxysmal AF underwent MDCT prior to pulmonary vein isolation (PVI). All patients were in sinus rhythm both during CT imaging and PVI. Multi-detector-row computed tomography was performed in 15 patients without ECG-gating (non-gated MDCT) and in 14 patients with retrospective ECG-gating (ECG-gated MDCT). Image quality of LA reconstructions from MDCT was rated on a five-point scale (from 1 = excellent to 5 = segmentation failed). Registration error between LA geometry obtained from EAM and MDCT was calculated as the mean distance between EAM points and MDCT surface. In all patients, LA was successfully segmented from MDCT data. The segmentation process took 2:31 +/- 0:54 min for non-gated MDCT and 2:36 +/- 0:47 min for ECG-gated MDCT (P = 0.8). Image quality scores of LA reconstructions from non-gated and ECG-gated MDCT were 1.3 +/- 0.6 and 1.4 +/- 0.7, respectively (P = 0.76). There was no significant difference in the registration error between non-gated and ECG-gated MDCT (1.8 +/- 0.2 vs. 1.9 +/- 0.3 mm, respectively; P = 0.6). The radiation dose of non-gated MDCT was significantly lower compared with ECG-gated MDCT (4.6 +/- 1.4 vs. 13.4 +/- 3.6 mSv, respectively; P < 0.001). CONCLUSION: Non-gated MDCT depicts LA with appropriate image quality for integrated EAM, while exposing patients to substantially lower radiation dose compared with ECG-gated MDCT.

Gadofosveset trisodium-enhanced magnetic resonance angiography of the left atrium--a feasibility study.

AIM: Imaging of the left atrium is regularly performed prior to pulmonary vein isolation. The aim of the study was to evaluate the feasibility of contrast-enhanced high-resolution magnetic resonance angiography (MRA) of the left atrium using the blood-pool contrast agent gadofosveset trisodium in comparison to noncontrast MRA. MATERIALS AND METHODS: Twenty consecutive patients were examined by free-breathing electrocardiogram-gated whole-heart MRA (reconstructed spatial resolution, 0.7mm x 0.6mm x 0.8mm) with a noncontrast T2-prepared steady state free precession sequence (T2-prep SSFP) and a gadofosveset trisodium-enhanced inversion-recovery SSFP sequence (CE IR-SSFP). Contrast-to-noise ratio (CNR) of blood in the left atrium was determined. Depiction of the left atrium was rated by two radiologists in consensus. A cardiologist segmented the MR data sets and rated depiction of the left atrium. RESULTS: Five of 20 patients had irregular breathing patterns with navigator efficiency less than 35% and were excluded from evaluation. CNR was significantly higher for CE IR-SSFP compared with T2-prep SSFP (18.4+/-5.3 vs. 11.7+/-3.5, p<0.01). Depiction of the left atrium by T2-prep SSFP was rated as good in four patients, moderate in ten patients, and poor in one patient, whereas depiction of the left atrium by CE IR-SSFP was rated as excellent in nine patients, good in four patients, and moderate in two patients. CE IR-SSFP allowed for semiautomated segmentation of the left atrium in 15 patients, whereas T2-prep SSFP allowed for segmentation only in ten patients. CONCLUSION: Gadofosveset trisodium-enhanced MRA of the left atrium is feasible with significantly improved image quality compared to noncontrast MRA.

Prospective randomized comparison of durability of bidirectional conduction block in the cavotricuspid isthmus in patients after ablation of common atrial flutter using cryothermy and radiofrequency energy: the CRYOTIP study.

BACKGROUND: Recent studies have shown that cryoablation and radiofrequency (RF) ablation are comparable with regard to success rates and safety in the treatment of common atrial flutter (AFL). Long-term success requires persistence of bidirectional conduction block (BCB) in the inferior cavotricuspid isthmus (CTI). OBJECTIVE: The purpose of this study was to determine the persistence of BCB in a prospective randomized multicenter trial of the two ablation techniques. METHODS: A total of 191 patients were randomized to RF ablation or cryoablation of the CTI using an 8-mm-tip catheter. In all patients, BCB was defined as the ablation end-point. Primary end-point of the study was nonpersistence of achieved BCB and/or ECG-documented relapse of common AFL within 3-month follow-up. RESULTS: Acute success rates were 91% (83/91) in the RF group and 89% (80/90) in the cryoablation group (P = NS). Invasive follow-up after 3 months with repeated electrophysiologic study was available for 60 patients in the RF group and 64 patients in the cryoablation group. Persistent BCB could be confirmed in 85% of the RF group versus 65.6% of the cryoablation group. The primary end-point was achieved in 15% of the RF group and 34.4% of the cryoablation group (P = .014). As a secondary end-point, pain perception during ablation was significant lower in the cryoablation group (P <.001). CONCLUSION: Persistence of BCB in patients treated with cryoablation reinvestigated after 3 months is inferior to that patients treated with RF ablation, as evidenced by the higher recurrence rate of common AFL seen in this study.

Initial experience using a forward directed, high-intensity focused ultrasound balloon catheter for pulmonary vein antrum isolation in patients with atrial fibrillation.

BACKGROUND: A high-intensity-focused ultrasound balloon catheter (HIFU-BC) is designed to isolate pulmonary veins (PV) outside the ostia (PV antrum). This catheter uses a parabolic CO2 balloon (behind water balloon) to focus a 20-, 25-, or 30-mm diameter ring of ultrasound forward of the balloon (parallel to catheter shaft). The purpose of this study is to test the safety and efficacy of the HIFU-BC for PV antrum isolation in patients with atrial fibrillation (AF). METHODS AND RESULTS: Twenty-seven patients with paroxysmal (19 patients) or persistent (8 patients) AF were studied. Double transseptal puncture was performed for left atrial deployment of a Lasso catheter (for PV mapping) and the 14 Fr HIFU-BC. The HIFU-BC was positioned outside the PV orifice over a guidewire. HIFU energy (acoustic power 45 watts) was applied for 40 seconds with a 20-mm sonicating ring and 40 or 60 seconds with a 25-mm or 30-mm sonicating ring. No other ablation system was utilized. PV antrum isolation was attempted using HIFU-BC in 78 of 104 PVs (25/27 RSPVs, all 23 LSPVs, all 23 LIPVs, all four left common trunks and 3/27 RIPVs). HIFU-BC successfully isolated 68 (87%) of the 78PV antra with 1-26 (median 3) HIFU applications. The complications include transient bleeding from a distal branch of the left superior PV resulting from guidewire manipulation in one patient and right phrenic nerve injury in another patient. No PV stenosis (>50% narrowing) and no LA-esophageal fistula occurred. At the 12-month follow-up, 16 (59%) of the 27 patients were free of symptomatic episodes of AF (only 3 of the 16 patients were receiving antiarrhythmic medications). CONCLUSIONS: Forward-focused HIFU applications isolated PVs outside the PV ostium with elimination of AF in 16 (59%) of the 27 patients at 12 months following the single ablation procedure.

Ostial PV isolation: is there a role for three-dimensional mapping?

Pulmonary vein (PV) isolation by elimination of spike potentials has been reported to cure drug refractory atrial fibrillation. Because of the heterogenous morphology of the PVs, sequential electroanatomic reconstruction of the PVs was performed in 39 patients (group A), who underwent subsequent PV isolation by interruption of all conductive myocardial fibers by distinct RF current applications using a "lasso" approach. In group B (157 patients), only biplane two-dimensional fluoroscopy was performed to guide the diagnostic and the ablation catheters. After reprocedures (in 7% of patients in group A and 22% of group B), which depicted a recurrence of a spike potential inside or at the ostium of >1 previously isolated PV in all restudied patients, stable sinus rhythm was documented in 69% of patients in group A and 60% of patients in group B. Reasons for the relapse of the previously eliminated spike potentials include a temporary ablation effect and a too distal interruption of the conducting myocardial fiber. Detailed knowledge of the individual three-dimensional morphology enhanced the clinical success rate of PV isolation but is time-consuming using CARTO (8.0 +/- 1.7 vs 5.0 +/- 1.6, P < 0.001). Further technical improvement to fuse the individual three-dimensional anatomy and the electrophysiological markers to a composed "electroanatomic" map may overcome this limitation in the future.

Characterization of reentrant circuits in left atrial macroreentrant tachycardia: critical isthmus block can prevent atrial tachycardia recurrence.

BACKGROUND: Left atrial macroreentrant tachycardia (LAMRT) has not been characterized in detail. METHODS AND RESULTS: Twenty-eight patients with LAMRT, including 4 patients with ablated typical atrial flutter (AFL), underwent electroanatomic mapping of the left atrium (LA) between February 1999 and October 2001. LA maps were performed during LAMRT in 26 patients and during sinus rhythm in 2 patients. Electrically silent areas or continuous lines of double potentials were identified as acquired anatomic barriers in all patients. In 23 of 26 patients with LAMRT mapping, 42 reentry circuits with a protected isthmus were identified. The isthmus was 11.8+/-5.9 mm wide, with the maximal amplitude of 0.07 to 3.61 mV. Radiofrequency pulses terminated all LAMRTs in 23 patients and resulted in conduction block across the isthmus in 20 patients. In 2 patients with sinus mapping, all identified isthmuses were ablated. Additionally, AFL was induced and ablated in 6 patients. Atrial tachycardia recurred in 4 patients: 3 patients without validated block across the isthmus presented with recurrence of the same LAMRT, and 1 patient without ablated cavotricuspid isthmus presented with AFL. All tachycardias were abolished during a second procedure. Of 25 patients with identified isthmuses, 20 patients were without atrial arrhythmia and 5 had only atrial fibrillation during a median follow-up of 14 months. CONCLUSION: The reentry circuit with a protected isthmus can be identified in 89% patients with LAMRT by electroanatomic mapping. The isthmuses were amenable to radiofrequency applications in most patients. No atrial tachycardia recurred in any patients with isthmus block.

Electroanatomic substrate of idiopathic left ventricular tachycardia: unidirectional block and macroreentry within the purkinje network.

BACKGROUND: An abnormal potential (retroPP) from the left posterior Purkinje network has been demonstrated during sinus rhythm (SR) in some patients with idiopathic left ventricular tachycardia (ILVT). We hypothesized that this potential can specifically be identified and be a critical substrate for ILVT. METHODS AND RESULTS: In 9 patients with ILVT and 6 control patients who underwent mapping of the left ventricle during SR using 3-dimensional electroanatomic mapping, an area with retroPP was found within the posterior Purkinje fiber network only in patients with ILVT. The earliest and latest retroPP was 185.4+/-57.4 and 465.2+/-37.3 ms after Purkinje potential; in the other patient with ILVT, an entire left ventricle mapping demonstrated a slow conduction area and passive retrograde activation along the posterior fascicle during ILVT. ILVT was noninducible in 3 patients after SR mapping. Diastolic potentials critical for ILVT during ILVT coincided with the earliest retroPP during SR in 7 patients. Mechanical termination of ILVT occurred in 5 patients. A single radiofrequency pulse was applied at the site with mechanical translation in 5 patients and the site with diastolic potential in 2 patients, and 3 radiofrequency pulses were delivered to the site with the earliest retroPP in the other 3 patients without inducible ILVT after SR mapping. No ILVT was inducible during control stimulation, and none recurred during follow-up of 9.1+/-5.1 months. CONCLUSION: In patients with ILVT, abnormal retroPP within the posterior Purkinje fiber network is a common finding. The earliest retroPP critical for ILVT substrate can be used for guiding successful ablation.