Shock efficacy of single and dual coil electrodes-new insights from the NORDIC ICD Trial.

Aims: Dual coil (DC) electrodes are preferred to single coil (SC) electrodes because of an assumed higher shock efficacy. However, DC-electrodes may be associated with an increased difficulty and risk of lead extraction. We aimed to compare SC- and DC-electrodes with respect to the first shock efficacy (FSE) after implantable cardioverter defibrillator (ICD) implantation. Methods and results: One thousand and seventy-seven patients of the NORDIC ICD trial were randomly assigned to first time ICD implantation with or without defibrillation (DF) testing. The electrode configuration was determined before randomization. One thousand and sixty-seven patients eventually received an ICD, 516 (48.4%) with a SC- and 551 (51.6%) with a DC-electrode. DC-electrodes were preferentially selected in older patients, renal failure, atrial fibrillation, dual chamber, Cardiac Resynchronization Therapy (CRT) devices, angiotensin-converting-enzyme (ACE) inhibitors/angiotensin (AT) receptor blockers and without Sotalol. However, the preference of the investigational site was dominant over clinical parameters. The DF energy at the final electrode position was higher in SC-electrodes (adjusted difference +1.15 J; P = 0.005; only patients tested). Less patients with DC-electrodes required intra-operative system reconfiguration (adjusted difference -3.9; P = 0.046; only patients tested). Using mixed logistic regression, the FSE was 92.6% in SC- and 97.8% in DC-electrodes (adjusted odds ratio 4.3 (95% confidence interval [1.9, 9.8]; P < 0.001)). Conclusion: Dual coil-electrode selection mainly depends on the preference of the investigational site and seems to be preferred in older patients, renal failure, atrial fibrillation, dual chamber, and CRT devices. Patients with DC-electrodes required less intraoperative system reconfigurations. Dual coil-electrodes provided a substantially higher FSE during follow-up. Mortality rates were not significantly different in patients with DC- and SC-electrodes.

Intra-operative defibrillation testing and clinical shock efficacy in patients with implantable cardioverter-defibrillators: the NORDIC ICD randomized clinical trial.

AIMS: This trial was designed to test the hypothesis that shock efficacy during follow-up is not impaired in patients implanted without defibrillation (DF) testing during first implantable cardioverter-defibrillator (ICD) implantation. METHODS AND RESULTS: Between February 2011 and July 2013, 1077 patients were randomly assigned (1 : 1) to first time ICD implantation with (n = 540) or without (n = 537) DF testing. The intra-operative DF testing was standardized across all participating centres, and all ICD shocks were programmed to 40 J irrespective of DF test results. The primary end point was the average first shock efficacy (FSE) for all true ventricular tachycardia and fibrillation (VT/VF) episodes during follow-up. The secondary end points included procedural data, serious adverse events, and mortality. During a median follow-up of 22.8 months, the model-based FSE was found to be non-inferior in patients with an ICD implanted without a DF test, with a difference in FSE of 3.0% in favour of the no DF test [confidence interval (CI) -3.0 to 9.0%, Pnon-inferiority <0.001 for the pre-defined non-inferiority margin of -10%). A total of 112 procedure-related serious adverse events occurred within 30 days in 94 patients (17.6%) tested compared with 89 events in 74 patients (13.9%) not tested (P = 0.095). CONCLUSION: Defibrillation efficacy during follow-up is not inferior in patients with a 40 J ICD implanted without DF testing. Defibrillation testing during first time ICD implantation should no longer be recommended for routine left-sided ICD implantation.

The NO Regular Defibrillation testing In Cardioverter Defibrillator Implantation (NORDIC ICD) trial: concept and design of a randomized, controlled trial of intra-operative defibrillation testing during de novo defibrillator implantation.

AIMS: Although defibrillation (DF) testing is still considered a standard procedure during implantable cardioverter-defibrillator (ICD) insertion and has been an essential element of all trials that demonstrated the survival benefit of ICD therapy, there are no large randomized clinical trials demonstrating that DF testing improves clinical outcome and if the outcome would remain the same by omitting DF testing. METHODS AND RESULTS: Between February 2011 and July 2013, we randomly assigned 1077 patients to ICD implantation with (n = 540) or without (n = 537) DF testing. The intra-operative DF testing was standardized across all participating centres. After inducing a fast ventricular tachycardia (VT) with a heart rate ≥240 b.p.m. or ventricular fibrillation (VF) with a low-energy T-wave shock, DF was attempted with an initial 15 J shock. If the shock reversed the VT or VF, DF testing was considered successful and terminated. If unsuccessful, two effective 24 J shocks were administered. If DF was unsuccessful, the system was reconfigured and another DF testing was performed. An ICD shock energy of 40 J had to be programmed in all patients for treatment of spontaneous VT/VF episodes. The primary endpoint was the average efficacy of the first ICD shock for all true VT/VF episodes in each patient during follow-up. The secondary endpoints included the frequency of system revisions, total fluoroscopy, implantation time, procedural serious adverse events, and all-cause, cardiac, and arrhythmic mortality during follow-up. Home Monitoring was used in all patients to continuously monitor the system integrity, device programming and performance. CONCLUSION: The NO Regular Defibrillation testing In Cardioverter Defibrillator Implantation (NORDIC ICD) trial is one of two large prospective randomized trials assessing the effect of DF testing omission during ICD implantation. CLINICALTRIALSGOV IDENTIFIER: NCT01282918.

Pulmonary vein isolation by radiosurgery: implications for non-invasive treatment of atrial fibrillation.

AIMS: Electrical isolation of the pulmonary veins (PVs) has been established in clinical routine as a curative treatment for atrial fibrillation (AF). While catheter ablation carries procedural risks, radiosurgery might be able to non-invasively induce lesions at the PV ostia to block veno-atrial electrical conduction. This porcine feasibility and dose escalation study determined the effect of radiosurgery on electrophysiologic properties of the left atrial-PV junction. METHODS AND RESULTS: Eight adult Goettingen mini-pigs underwent electrophysiological voltage mapping in the left atrium and the upper right PV. Radiation was delivered with a conventional linear accelerator. A single homogeneous dose ranging from 22.5 to 40 Gy was applied circumferentially to the target vein antrum. Six months after radiosurgery, electrophysiological mapping was repeated and a histological examination performed. Voltage mapping consistently showed electrical potentials in the upper right PV at baseline. Pacing the target vein prompted atrial excitation, thus proving veno-atrial electrical conduction. After 6 months, radiation had reduced PV electrogram amplitudes. This was dose dependent with a mean interaction effect of -5.8%/Gy. Complete block of atrio-venous electrical conduction occurred after 40 Gy dose application. Histology revealed transmural scarring of the targeted PV musculature with doses >30 Gy. After 40 Gy, it spanned the entire circumference in accordance with pulmonary vein isolation. CONCLUSION: Pulmonary vein isolation to treat AF can be achieved by radiosurgery with a conventional linear accelerator. Yet, it requires a high radiation dose which might limit clinical applicability.

Rationale and design of the MONITOR-ICD study: a randomized comparison of economic and clinical effects of automatic remote MONITORing versus control in patients with Implantable Cardioverter Defibrillators.

BACKGROUND AND AIMS: Implantable cardioverter defibrillator (ICD) remote follow-up and ICD remote monitoring (RM) are established means of ICD follow-up. The reduction of the number of in-office visits and the time to decision is proven, but the true clinical benefit is still unknown. Cost and cost-effectiveness of RM remain leading issues for its dissemination. The MONITOR-ICD study has been designed to assess costs, cost-effectiveness, and clinical benefits of RM versus standard-care follow-up in a prospective multicenter randomized controlled trial. METHODS AND RESULTS: Patients indicated for single- or dual-chamber ICD are eligible for the study and are implanted an RM-capable Biotronik ICD (Lumax VR-T or Lumax DR-T; Biotronik SE & Co KG, Berlin, Germany). Implantable cardioverter defibrillator programming and alert-based clinical responses in the RM group are highly standardized by protocol. As of December 2011, recruitment has been completed, and 416 patients have been enrolled. Subjects are followed-up for a minimum of 12months and a maximum of 24months, ending in January 2013. Disease-specific costs from a societal perspective have been defined as primary end point and will be compared between RM and standard-care groups. Secondary end points include ICD shocks (including appropriate and inappropriate shocks), cardiovascular hospitalizations and cardiovascular mortality, and additional health economic end points. CONCLUSIONS: The MONITOR-ICD study will be an important randomized RM study to report data on a primary economic end point in 2014. Its results on ICD shocks will add to the currently available evidence on clinical benefit of RM.

Improved lesion formation using the novel 28 mm cryoballoon in atrial fibrillation ablation: analysis of biomarker release.

AIMS: Recently, a novel second-generation (G2) cryoballoon (CB) was introduced. Comparative analysis of lesion formation in terms of myocardial biomarker release [first-generation CB (G1) vs. G2] has not been studied. To compare myocardial biomarker release using the 28 mm G1 vs. G2 CB. METHODS AND RESULTS: In patients (patients) treated with the simplified single big CB (SBCB) strategy for pulmonary vein isolation (PVI), myocardial biomarkers [troponin T (TnT), creatine kinase, lactic dehydrogenase (LDH)] were measured at 12, 24, and 48 h after PVI. Two groups were defined: Group 1 (G1; freezing time: 300 s), Group 2 (G2; freezing time: 240 s). Mean biomarker peak values were compared. To correct for between-group differences in cumulative freezing time, an index calculated as peak biomarker release divided by cumulative freezing time was calculated. Sixty-six CB PVI procedures (G1: 33 patients, G2: 33 patients) were analysed. Pulmonary vein isolation was achieved in all the patients using the simplified SBCB technique only. Mean freezing time (51 ± 10 vs. 33 ± 6 min, P < 0.01) was significantly shorter in G2. All biomarker levels tended to be higher in G2 vs. G1. The indexed biomarkers values were significantly higher in G2: TnT: 18.8 ± 8.5 vs. 32.3 ± 13.6 pg/L/min (P < 0.01); creatinephosphokinase: 6.7 ± 2.7 vs. 11.7 ± 3.9 U/L/min (P < 0.01); LDH: 5.2 ± 1.0 vs. 9.1 ± 2.7 U/L/min (P < 0.01). On a 6-month follow-up (180 days), G2 revealed a significantly higher success rate (20/33 vs. 28/33; P = 0.027). CONCLUSION: Pulmonary vein isolation using the G2 CB increased the myocardial biomarker release index and is linked to a significantly improved 6 months success rate.

Improved procedural efficacy of pulmonary vein isolation using the novel second-generation cryoballoon.

INTRODUCTION: The cryoballoon technology has the potential to isolate a pulmonary vein (PV) with a single energy application. However, using the first-generation cryoballoon (CB-1G) repeated freezing or additional focal ablation is often necessary. The novel second-generation cryoballoon (CB-2G) features a widened zone of optimal cooling comprising the whole frontal hemisphere. The aim of this study was to investigate the impact of the novel design on procedural efficacy of cryoballoon PV isolation (CB-PVI). METHODS AND RESULTS: Single transseptal CB-PVI using an endoluminal spiral mapping catheter was performed in 60 consecutive patients (CB-1G, 28 mm, 300 seconds application time: 30 patients; CB-2G, 28 mm, 240 seconds application time: 30 patients). When compared to the CB-1G, using the CB-2G increased single-shot PVI rate from 51% to 84% (P < 0.001) and decreased procedure duration (128 ± 27 vs 98 ± 30 minutes; P < 0.001), and fluoroscopy exposure time (19.5 ± 7.4 vs 13.4 ± 5.3 min; P = 0.001). Effective CB-2G PVI could be performed with increased real-time PVI visualization rate (49% vs 76%; P < 0.001). Time to PVI (T(PVI)) was shorter in the CB-2G group (79 ± 60 vs. 52 ± 36 seconds; P = 0.049). Procedure-related complications occurred in 2 patients in the CB-1G group and 1 patient in the CB-2G group. CONCLUSIONS: The CB-2G significantly improved procedural efficacy compared to the CB-1G and provided reliable T(PVI) measurement. T(PVI) may be used to adjust application time and number individually in future studies. Final conclusions regarding the safety profile of the CB-2G requires additional research.

Should all dysfunctional high-voltage leads be extracted? Results of a single-centre long-term registry.

AIMS: A considerable number of lead defects occurs during long-term cardioverter defibrillator therapy. Evidence-based strategies for the handling of chronically implanted, non-functional high-voltage (HV) leads are mandatory. METHODS AND RESULTS: Patient outcome after abandonment of HV leads was retrospectively compared with patient outcome following other lead revision strategies and following primary implantation. A total of 903 consecutive patients undergoing 997 implantable cardioverter defibrillator (ICD) implantations or lead revisions were followed for a mean period of 48.8 ± 37.8 months. One or more additional HV leads were placed in 60 patients. An additional pace/sense lead was implanted in 13 patients. Extraction and replacement of a dysfunctional HV lead was performed in 21 patients. The overall rate of complications including artefact sensing, ineffective defibrillation, symptomatic subclavian vein thrombosis, and other lead defects did not differ between patients with and without an additional HV lead (10.0 vs. 8.9%, P = 0.32). Survival without lead associated complications did not differ between groups. Results remained unchanged after correction for covariates. CONCLUSIONS: Abandoned HV leads did not increase the risk of ICD system-related complications in the majority of patients. Thus, a general lead extraction policy of dysfunctional HV leads cannot be advised in an average ICD population. Recommendations may not apply for young and physically active patients, in whom HV lead extraction must be considered.

A strategy to achieve CRT response in permanent atrial fibrillation without obligatory atrioventricular node ablation.

BACKGROUND: Cardiac resynchronization therapy (CRT) is an established method in patients with severe heart failure and wide QRS configuration, particularly during sinus rhythm (SR). In CRT patients with permanent atrial fibrillation (AF), there is no general consensus regarding the need for atrioventricular node (AVN) ablation. The aim of this study was to evaluate the benefit of CRT in permanent AF with and without AVN ablation. METHODS: New York Heart Association classification, QRS duration, and echocardiographic parameters were assessed before and after CRT with a follow-up of 12 ± 3 months. Two hundred thirty patients in SR and 46 patients with permanent AF of 2.1 ± 0.5 years duration were studied. AVN ablation was performed only in AF patients with insufficient pharmacological rate control evidenced by ≤80 % ventricular stimulation. RESULTS: Fifteen AF patients underwent AVN ablation. Biventricular pacing comparably improved functional status, left ventricular ejection fraction, and left ventricular end-diastolic dimensions in all treated groups. Biventricular stimulation percentage was 10% lower in pharmacologically treated AF patients over 1 year as compared to patients in SR and to AF patients undergoing AVN ablation, which did not affect outcome in this patient population. CONCLUSION: In patients with permanent AF and CRT, an AVN ablation strategy might not be strictly required in all patients.

ReSurveyGermany: Vegetation-plot time-series over the past hundred years in Germany.

Vegetation-plot resurvey data are a main source of information on terrestrial biodiversity change, with records reaching back more than one century. Although more and more data from re-sampled plots have been published, there is not yet a comprehensive open-access dataset available for analysis. Here, we compiled and harmonised vegetation-plot resurvey data from Germany covering almost 100 years. We show the distribution of the plot data in space, time and across habitat types of the European Nature Information System (EUNIS). In addition, we include metadata on geographic location, plot size and vegetation structure. The data allow temporal biodiversity change to be assessed at the community scale, reaching back further into the past than most comparable data yet available. They also enable tracking changes in the incidence and distribution of individual species across Germany. In summary, the data come at a level of detail that holds promise for broadening our understanding of the mechanisms and drivers behind plant diversity change over the last century.

Remote monitoring and clinical outcomes: details on information flow and workflow in the IN-TIME study.

AIMS: Randomized clinical trials investigating a possible outcome effect of remote monitoring in patients with implantable defibrillators have shown conflicting results. This study analyses the information flow and workflow details from the IN-TIME study and discusses whether differences of message content, information speed and completeness, and workflow may contribute to the heterogeneous results. METHODS AND RESULTS: IN-TIME randomized 664 patients with an implantable cardioverter/defibrillator indication to daily remote monitoring vs. control. After 12 months, a composite clinical score and all-cause mortality were improved in the remote monitoring arm. Messages were received on 83.1% of out-of-hospital days. Daily transmissions were interrupted 2.3 times per patient-year for more than 3 days. During 1 year, absolute transmission success declined by 3.3%. Information on medical events was available after 1 day (3 days) in 83.1% (94.3%) of the cases. On all working days, a central monitoring unit informed investigators of protocol defined events. Investigators contacted patients with a median delay of 1 day and arranged follow-ups, the majority of which took place within 1 week of the event being available. CONCLUSION: Only limited data on the information flow and workflow have been published from other studies which failed to improve outcome. However, a comparison of those data to IN-TIME suggest that the ability to see a patient early after clinical events may be inferior to the set-up in IN-TIME. These differences may be responsible for the heterogeneity found in clinical effectiveness of remote monitoring concepts.

Implant-based multi-parameter telemonitoring of patients with heart failure and a defibrillator with vs. without cardiac resynchronization therapy option: a subanalysis of the IN-TIME trial.

AIMS: In the IN-TIME trial, automatic daily implant-based multiparameter telemonitoring significantly improved clinical outcomes in patients with chronic systolic heart failure and implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D). We compared IN-TIME results for ICD and CRT-D subgroups. METHODS: Patients with LVEF ≤ 35%, NYHA class II/III, optimized drug treatment, no permanent atrial fibrillation, and a dual-chamber ICD (n = 274) or CRT-D (n = 390) were randomized 1:1 to telemonitoring or no telemonitoring for 12 months. Primary outcome measure was a composite clinical score, classified as worsened if the patient died or had heart failure-related hospitalization, worse NYHA class, or a worse self-reported overall condition. RESULTS: The prevalence of worsened score at study end was higher in CRT-D than ICD patients (26.4% vs. 18.2%; P = 0.014), as was mortality (7.4% vs. 4.1%; P = 0.069). With telemonitoring, odds ratios (OR) for worsened score and hazard ratios (HR) for mortality were similar in the ICD [OR = 0.55 (P = 0.058), HR = 0.39 (P = 0.17)] and CRT-D [OR = 0.68 (P = 0.10), HR = 0.35 (P = 0.018)] subgroups (insignificant interaction, P = 0.58-0.91). CONCLUSION: Daily multiparameter telemonitoring has a potential to reduce clinical endpoints in patients with chronic systolic heart failure both in ICD and CRT-D subgroups. The absolute benefit seems to be higher in higher-risk populations with worse prognosis.

Ballistic arterial trauma to the lower extremity: recent South African experience.

The aim of this study was to determine the current outcome of gunshots to the arteries of the lower extremity. The authors conducted a retrospective analysis of 104 patients with gunshots to the femoral (n=71) and popliteal (n=33) artery. One hundred four patients presented over the 60-month period. Ninety-six (92%) were male and eight of 104 female. Ninety-nine were gunshot injuries, five from shotguns. Nine patients had injury to the common femoral artery, 62 patients had injury to the superficial femoral artery, and 33 had popliteal artery injury. One patient died in the emergency room and another died in the postoperative period, giving an overall in-hospital mortality of two of 104 (1.9%). Forty-three of 70 femoral reconstructions had completion angiograms compared with 20 of 32 popliteal artery reconstructions (P=1). Nineteen of 63 (30%) of the completion angiograms prompted revision of the reconstruction. Of the 63 patients who had completion angiograms, two of 63 (3%) required amputation. Seven of 39 (18%) patients who did not have completion angiograms required amputation (P = 0.025). Including the primary amputation, there were 10 amputations in the 103 patients (9.7%) who survived to undergo operation. Ballistic arterial trauma of the lower limb leads to significant disability. Completion arteriography leads to revision of the reconstruction in nearly one-third of instances and significantly reduces amputation rate.

Ventricular fibrillation induced by stretch pulse: implications for sudden death due to commotio cordis.

INTRODUCTION: Nonpenetrating chest wall impact (commotio cordis) may lead to sudden cardiac death due to the acute initiation of ventricular fibrillation (VF). VF may result from sudden stretch during a vulnerable window, which is determined by repolarization inhomogeneity. METHODS: We examined action potential morphologies and VF inducibility in response to sudden myocardial stretch in the left ventricle (LV). In six Langendorff perfused rabbit hearts, the LV was instrumented with a fluid-filled balloon. Increasing volume and pressure pulses were applied at different times of the cardiac cycle. Monophasic action potentials (MAPs) were recorded simultaneously from five LV epicardial sites. Inter-site dispersion of repolarization was calculated in the time and voltage domains. RESULTS: Sudden balloon inflation induced VF when pressure pulses of 208-289 mmHg were applied within a window of 35-88 msec after MAP upstroke, a period of intrinsic increase in repolarization dispersion. During the pressure pulse, MAPs revealed an additional increase in repolarization dispersion (time domain) by 9 +/- 6 msec (P < 0.01). The maximal difference in repolarization levels (voltage domain) between sites increased from 19 +/- 3% to 26 +/- 3% (P < 0.05). Earliest stretch-induced activation was observed near a site with early repolarization, while sites with late repolarization showed delayed activation. CONCLUSIONS: Sudden myocardial stretch can elicit VF when it occurs during a vulnerable window that is based on repolarization inhomogeneity. Stretch pulses applied during this vulnerable window can lead to nonuniform activation. Repolarization dispersion might play a crucial role in the occurrence of fatal tachyarrhythmias during commotio cordis.

Modulation of ventricular repolarization in patients with transient left ventricular apical ballooning: a case control study.

OBJECTIVE: Even though diffuse T wave inversion and prolongation of the QT interval in the surface electrocardiogram (ECG) have been consistently reported in patients with transient stress-induced left ventricular apical ballooning (AB), ventricular repolarization has not yet been systematically investigated in this clinical entity. BACKGROUND: AB, an emerging syndrome that mimics acute ST-segment elevation myocardial infarction (MI), is characterized by reversible left ventricular wall motion abnormalities in the absence of obstructive coronary heart disease and significant QT interval prolongation. METHODS: We prospectively enrolled 22 consecutive patients (21 women, median age 65 years) with transient left ventricular AB. A total of 22 age-, gender-, body-mass-index-, and left-ventricular-function-matched patients with acute anterior ST-segment elevation MI undergoing successful direct percutaneous coronary intervention for a proximal occlusion of the LAD, as well as 22 healthy volunteers served as control groups. Beat-to-beat QT interval and QT interval dynamicity were determined from 24-hour Holter ECGs, recorded on the third day after hospital admission. RESULTS: There were no significant differences in baseline clinical characteristics, except higher peak enzyme release in MI patients. Compared with MI patients, AB patients exhibited significantly prolonged mean QT intervals and rate-corrected QT intervals (QT: 418 +/- 37 vs 384 +/- 33 msec, P < 0.01; QTcBazett: 446 +/- 40 vs 424 +/- 35 msec, P < 0.05; QTcFridericia: 437 +/- 35 vs 412 +/- 31 msec, P < 0.05). Mean RR intervals tended to be higher in AB patients, without reaching statistical significance (877 +/- 96 vs 831 +/- 102 msec, P = NS). The linear regression slope of QT intervals plotted against RR intervals was significantly flatter in AB patients at both day- and nighttime (QT/RR slopeday: 0.18 +/- 0.04 vs 0.22 +/- 0.06, P < 0.01; QT/RR slopenight: 0.12 +/- 0.03 vs 0.17 +/- 0.05, P < 0.01). CONCLUSION: The present study is the first to demonstrate significant differences of QT interval modulation in patients with transient left ventricular AB and acute ST-segment elevation MI. Even though transient AB is associated with a significant QT interval prolongation, rate adaptation of ventricular repolarization (i.e., QT dynamicity) is not significantly altered, suggesting a differential effect of autonomic nervous activity on the ventricular myocardium in transient AB and in acute MI.

The Negligible Influence of Chronic Obesity on Hospitalization, Clinical Status, and Complications in Elective Posterior Lumbar Interbody Fusion.

Background. Posterior lumbar interbody fusion (PLIF) is a common surgical treatment for degenerative spinal instability, but many surgeons consider obesity a contraindication for elective spinal fusion. The aim of this study was to analyze whether obesity has any influence on hospitalization parameters, change in clinical status, or complications. Methods. In this prospective study, regression analysis was used to analyze the influence of the body mass index (BMI) on operating time, postoperative care, hospitalization time, type of postdischarge care, change in paresis or sensory deficits, pain level, wound complications, cerebrospinal fluid leakage, and implant complications. Results. Operating time increased only 2.5 minutes for each increase of BMI by 1. The probability of having a wound complication increased statistically with rising BMI. Nonetheless, BMI accounted for very little of the variation in the data, meaning that other factors or random chances play a much larger role. Conclusions. Obesity has to be considered a risk factor for wound complications in patients undergoing elective PLIF for degenerative instability. However, BMI showed no significant influence on other kinds of peri- or postoperative complications, nor clinical outcomes. So obesity cannot be considered a contraindication for elective PLIF.

Treatment Planning Considerations for Robotic Guided Cardiac Radiosurgery for Atrial Fibrillation.

PURPOSE: Robotic guided stereotactic radiosurgery has recently been investigated for the treatment of atrial fibrillation (AF). Before moving into human treatments, multiple implications for treatment planning given a potential target tracking approach have to be considered. MATERIALS & METHODS: Theoretical AF radiosurgery treatment plans for twenty-four patients were generated for baseline comparison. Eighteen patients were investigated under ideal tracking conditions, twelve patients under regional dose rate (RDR = applied dose over a certain time window) optimized conditions (beam delivery sequence sorting according to regional beam targeting), four patients under ultrasound tracking conditions (beam block of the ultrasound probe) and four patients with temporary single fiducial tracking conditions (differential surrogate-to-target respiratory and cardiac motion). RESULTS: With currently known guidelines on dose limitations of critical structures, treatment planning for AF radiosurgery with 25 Gy under ideal tracking conditions with a 3 mm safety margin may only be feasible in less than 40% of the patients due to the unfavorable esophagus and bronchial tree location relative to the left atrial antrum (target area). Beam delivery sequence sorting showed a large increase in RDR coverage (% of voxels having a larger dose rate for a given time window) of 10.8-92.4% (median, 38.0%) for a 40-50 min time window, which may be significant for non-malignant targets. For ultrasound tracking, blocking beams through the ultrasound probe was found to have no visible impact on plan quality given previous optimal ultrasound window estimation for the planning CT. For fiducial tracking in the right atrial septum, the differential motion may reduce target coverage by up to -24.9% which could be reduced to a median of -0.8% (maximum, -12.0%) by using 4D dose optimization. The cardiac motion was also found to have an impact on the dose distribution, at the anterior left atrial wall; however, the results need to be verified. CONCLUSION: Robotic AF radiosurgery with 25 Gy may be feasible in a subgroup of patients under ideal tracking conditions. Ultrasound tracking was found to have the lowest impact on treatment planning and given its real-time imaging capability should be considered for AF robotic radiosurgery. Nevertheless, advanced treatment planning using RDR or 4D respiratory and cardiac dose optimization may be still advised despite using ideal tracking methods.

Alternans of atrial action potentials during atrial flutter as a precursor to atrial fibrillation.

BACKGROUND: The mechanisms underlying the transition of typical atrial flutter (Afl) to fibrillation (AF) remain unclear. We set out to test the hypothesis that Afl disorganizes to AF via alternans of atrial action potentials. METHODS AND RESULTS: In 38 patients with Afl, monophasic action potentials (MAPs) were recorded at the isthmus and either high or low right atrium (HRA, LRA) during overdrive pacing to 160 ms or to the initiation of AF, whichever came first. MAP duration measured at 90% repolarization was longer at the isthmus in all patients, and failed to shorten with rate, compared with the HRA (n=38) or LRA (n=5). In 20 patients who developed AF, progressive pacing first caused alternans of isthmus MAP duration and amplitude at mean cycle length of 219+/-45 ms, followed by AF at a mean onset cycle length of 184+/-38 ms. Subsets of this group showed spontaneous action potential duration alternans at the isthmus (11 of 20 patients) and 2:1 isthmus conduction block immediately preceding AF (4 of 20 patients). In the 18 patients who did not develop AF, MAP alternans was less common (9 of 18 patients; P<0.0003), and occurred only at faster pacing (cycle length=169+/-25 ms; P<0.05). CONCLUSIONS: In patients with typical Afl, action potential duration rate maladaptation at the isthmus may lead to action potential duration alternans and conduction block preceding the transition to AF. These isthmus characteristics may enable the spontaneous initiation of AF through wavefront fractionation and may explain the benefits of isthmus ablation in preventing AF recurrence.

Impact of infarct-related artery flow on QT dynamicity in patients undergoing direct percutaneous coronary intervention for acute myocardial infarction.

BACKGROUND: Complete coronary artery reperfusion in acute myocardial infarction (AMI) has been shown to significantly improve survival. Electrical stability may be the decisive mechanism for this beneficial effect. Because electrical stability is largely dependent on ventricular repolarization, we sought to determine the impact of a modern reperfusion strategy (ie, direct percutaneous coronary intervention [PCI]) on QT dynamicity in AMI and examined its association with infarct-related artery flow. METHODS AND RESULTS: We prospectively investigated QT dynamicity in 128 patients undergoing direct PCI for a first AMI. Slopes and correlation coefficients of the linear QT/RR regression were determined in the time interval before reperfusion, within the initial hour after reperfusion, and within the remaining recording period from Holter ECG recordings, which were initiated on admission. Subgroup analysis based on TIMI 3 (n=100) and TIMI 2 (n=28) flow after PCI revealed no significant differences in QT/RR slope before PCI (0.145+/-0.12 versus 0.160+/-0.19,P=NS). After PCI, QT/RR slopes increased only in the TIMI 2 subgroup (P<0.05). In TIMI 2 patients, QT/RR slopes were significantly steeper in the hour after PCI and in the remaining recording period, respectively (0.155+/-0.12 versus 0.192+/-0.15,P<0.05, and 0.159+/-0.10 versus 0.210+/-0.17,P<0.01). CONCLUSIONS: Alterations of QT dynamicity in patients with incomplete reperfusion may suggest an altered electrical restitution, potentially providing a substrate for serious ventricular arrhythmias. Thus, our findings offer new insights into mechanisms by which complete reperfusion may affect electrical stability.