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It is unclear if there is a consistent signature in breath patterns prior to an impending obstructive apneic event in patients with sleep-disordered breathing (SDB). To use continuous recordings of ambient sound in sleep using a smartphone to track auditory signatures of breaths and measure their regularity preceding apneic events. We studied 50 patients evaluated for SDB in whom sound was recorded using smartphones concurrently with polysomnography (PSG). Whole-night sound files were analyzed for time and frequency domain analyses of breath periodicity during periods of normal and sleep-disordered breathing. Fifty patients (44% women, 42.0 ± 9.4 years old, BMI 32.8 ± 10.8 kg/m2) recorded sound, of whom 30 were diagnosed with OSA and 20 were not. We analyzed a total of 497 apneic (≥10 s) and 481 non-apneic intervals, confirmed by PSG. Interbreath intervals were 3.75 ± 0.62 s for 1 min in quiet breathing, with SD 1.11 ± 0.48 s that increased to 4.16 ± 3.06 s in successive 60-s epochs up to apnea (p

PURPOSE: Diagnosis of obstructive sleep apnea by the gold-standard of polysomnography (PSG), or by home sleep testing (HST), requires numerous physical connections to the patient which may restrict use of these tools for early screening. We hypothesized that normal and disturbed breathing may be detected by a consumer smartphone without physical connections to the patient using novel algorithms to analyze ambient sound. METHODS: We studied 91 patients undergoing clinically indicated PSG. Phase I: In a derivation cohort (n = 32), we placed an unmodified Samsung Galaxy S5 without external microphone near the bed to record ambient sounds. We analyzed 12,352 discrete breath/non-breath sounds (386/patient), from which we developed algorithms to remove noise, and detect breaths as envelopes of spectral peaks. Phase II: In a distinct validation cohort (n = 59), we tested the ability of acoustic algorithms to detect AHI < 15 vs AHI > 15 on PSG. RESULTS: Smartphone-recorded sound analyses detected the presence, absence, and types of breath sound. Phase I: In the derivation cohort, spectral analysis identified breaths and apneas with a c-statistic of 0.91, and loud obstruction sounds with c-statistic of 0.95 on receiver operating characteristic analyses, relative to adjudicated events. Phase II: In the validation cohort, automated acoustic analysis provided a c-statistic of 0.87 compared to whole-night PSG. CONCLUSIONS: Ambient sounds recorded from a smartphone during sleep can identify apnea and abnormal breathing verified on PSG. Future studies should determine if this approach may facilitate early screening of SDB to identify at-risk patients for definitive diagnosis and therapy. CLINICAL TRIALS: NCT03288376; clinicaltrials.org

Introduction: The Stereotaxis Niobe® Magnetic Navigation System (MNS, Stereotaxis, Inc., St. Louis, MO, USA) allows for remote-control navigation of magnetically enabled catheters and guidewires for clinical ablation and electrophysiology (EP) device placement using two permanent magnets located on opposite sides of the patient table. Our objective was to provide a clinical framework for expected navigational accuracy during a case by calibrating the system's reproducibility using a realistic heart phantom under various conditions. Methods and Results: We performed two sets of experiments to demonstrate the accuracy of magnetic catheters using the MNS. The first experiment calibrated deviations in the deflection of an EP catheter by the magnetic system from the expected angles using proprietary algorithms based on predicted geometry. We found that the magnetic fields produced catheter angulation movements within a mean of 4° of biophysical predictions. The second experiment used the MNS to navigate these catheters to previously labeled target positions within a phantom heart model and estimated the actual displacement from desired target positions. We found that the accuracy for reaching the desired targets was 100%. Conclusions: Remote navigation of magnetically enabled EP catheters using the MNS accurately and reproducibly navigates to target sites in a heart phantom. This may enable more complex, successful, and time-efficient procedures in the cardiac catheterization laboratory.

Summary The adverse event (AE) profile of lay volunteer CPR and public access defibrillation (PAD) programs is unknown. We undertook to investigate the frequency, severity, and type of AE's occurring in widespread PAD implementation. Design A randomized-controlled clinical trial. Setting One thousand two hundred and sixty public and residential facilities in the US and Canada. Participants On-site, volunteer, lay personnel trained in CPR only compared to CPR plus automated external defibrillators (AEDs). Intervention Persons experiencing possible cardiac arrest receiving lay volunteer first response with CPR + AED compared with CPR alone. Main outcome measure An AE is defined as an event of significance that caused, or had the potential to cause, harm to a patient or volunteer, or a criminal act. AE data were collected prospectively. Results Twenty thousand three hundred and ninety six lay volunteers were trained in either CPR or CPR + AED. One thousand seven hundred and sixteen AEDs were placed in units randomized to the AED arm. There were 26,389 exposure months. Only 36 AE's were reported. There were two patient-related AEs: both patients experienced rib fractures. There were seven volunteer-related AE's: one had a muscle pull, four experienced significant emotional distress and two reported pressure by their employee to participate. There were 27 AED-related AEs: 17 episodes of theft involving 20 devices, three involved AEDs that were placed in locations inaccessible to the volunteer, four AEDs had mechanical problems not affecting patient safety, and three devices were improperly maintained by the facility. There were no inappropriate shocks and no failures to shock when indicated (95% upper bound for probability of inappropriate shock or failure to shock = 0.0012). Conclusions AED use following widespread training of lay-persons in CPR and AED is generally safe for the volunteer and the patient. Lay volunteers may report significant, usually transient, emotional stress following response to a potential cardiac arrest. Within the context of this prospective, randomized multi-center study, AEDs have an exceptionally high safety profile when used by trained lay responders.

Objectives: To evaluate whether automated external defibrillator (AED) training and AED availability affected the response of volunteer rescuers and performance of cardiopulmonary resuscitation (CPR) in presumed out-of-hospital cardiac arrest (OOH-CA) during the multicenter Public Access Defibrillation Trial. Methods: The Public Access Defibrillation Trial recruited 1,260 facilities in 24 North American regional sites to participate in a trial addressing survival from OOH-CA when AED training and availability were added to a volunteer-based emergency response team. Volunteers at each facility were trained to perform either CPR alone (CPR) or CPR in conjunction with AED use (CPR+AED) according to randomized assignments. This study reports the frequency of response and initiation of CPR actions (chest compressions and/or ventilations) by volunteers in the CPR and CPR+AED study groups. Results: A total of 314 presumed OOH-CA episodes occurred in CPR facilities, and 308 occurred in CPR+AED facilities. The volunteers were matched well for age, gender, and other features. Overall, ventilations (23.1% vs. 13.1%), chest compressions (24.4% vs. 12.1%), and both actions (19.8% vs. 10.5%; all p < 0.05) were more commonly performed in OOH-CA cases in the CPR+AED group. However, when only OOH-CA cases with volunteers responding were analyzed, the rates of CPR actions were similar. In the subgroup of CPR+AED cases with a responding volunteer, the AED was turned on for only 47% of cases. Volunteers initiated a CPR action more commonly when the AED was turned on (60.7% vs. 39.3%; p = 0.003). Conclusions: In the Public Access Defibrillation Trial, rates of CPR actions for presumed OOH-CA victims were low but similar for CPR and CPR+AED responding volunteer rescuers. Factors associated with volunteer response, CPR action initiation, and AED activation warrant further investigation.

A multicenter prospective study was performed to assess the results and risks associated with radiofrequency ablation in children. This report focuses on recurrences following initially successful ablation.Patients recruited for the study were aged 0 to 16 years and had supraventricular tachycardia due to accessory pathways or atrioventricular nodal reentrant tachycardia (AVNRT), excluding patients with more than trivial congenital heart disease. A total of 481 patients were recruited into the prospective cohort and were followed at 2, 6, and 12 months following ablation.There were 517 successfully ablated substrates out of 540 attempted (95.7%). Loss to follow-up for individual substrates was 3.3%, 10.6%, and 21.2% at 2, 6, and 12 months, respectively. Recurrence was observed in 7.0%, 9.2%, and 10.7% of these substrates at 2, 6, and 12 months, respectively (adjusted for loss to follow-up as an independent source of data censoring). Recurrence rate varied by substrate location (24.6% for right septal, 15.8% for right free wall, 9.3% for left free wall, and 4.8% for left septal), as well as for AVNRT versus all others (4.8% vs 12.9%) at 12 months. The recurrence rate was higher for substrates ablated using power control but was not a function of whether isoproterenol was used for postablation testing.Recurrence after initially successful ablation occurs commonly in children. It is least common after AVNRT ablation and most common following ablation of right-sided pathways. These results serve as a benchmark for the time course of recurrence following initially successful ablation of supraventricular tachycardia in children.

We report the development and implementation of a program designed to assign patients preoperatively to either transplant or Norwood procedure based on a score derived from known risk factors and to enhance postoperative care of infants undergoing the Norwood procedure.A weighted score for each of six variables comprised the scoring system: ventricular function, tricuspid regurgitation, ascending aortic diameter, atrial septal defect blood flow characteristics, blood type, and age. The scoring system was used to prospectively assign mortality risk and lead to recommendation of either Norwood procedure or transplantation.Survival following the Norwood procedure significantly improved after the management program was implemented (88% versus 40% at 48 hours, 57% versus 10% at 30 days, and 50% versus 10% at 1 year, p0.0001 at each time point). The survival of the group that received a score of 7 or less (high risk) who underwent the Norwood procedure was 78% at 48 hours, 44% at 30 days, and 33% at 1 year; survival rates among patients considered lower risk (greater than 7) were 100% at 48 hours and 80% at 30 days and 1 year. Transplant outcomes remained unchanged.We report improved survival following the Norwood procedure after the implementation of an institutional management approach aimed at improving the outcome of infants with hypoplastic left heart syndrome and may help neutralize historical biases toward Norwood procedure or transplantation.

The PAD Trial is a prospective, multicenter, randomized clinical study testing whether volunteer, non-medical responders can improve survival from out-of-hospital cardiac arrest (OOH-CA) by using automated external defibrillators (AEDs). These lay volunteers, who have no traditional responsibility to respond to a medical emergency as part of their primary job description, will form part of a comprehensive, integrated community approach to the treatment of OOH-CA. The study is being conducted at 24 field centers in the United States and Canada. Approximately 1000 community units (e.g. apartment or office buildings, gated communities, sports facilities, senior centers, shopping malls, etc.) were randomized to treatment by trained laypersons who will provide either cardiopulmonary resuscitation (CPR) alone or CPR plus use of an AED, while awaiting arrival of the community's emergency medical services responders. The primary endpoint is the number of OOH-CA victims who survive to hospital discharge. Secondary endpoints include neurological status, health-related quality of life (HRQL), cost, and cost-effectiveness. Data collection will last approximately 15 months and is expected to be completed in September 2003.

SEHRA, R., et al.: End Tidal CO2 Is a Quantitative Measure of Cardiac Arrest.Purpose of the study: Predictors of severity of cardiac arrest or efficacy of cardiopulmonary resuscitation are few. Respiratory end tidal CO2 (ETCO) is a marker of pulmonary blood flow and, possibly, cardiac arrest. The purpose of this study was to evaluate ETCO as a quantitative marker of cardiac arrest in a human model of ventricular fibrillation (VF). Methods: Thirty-one cardiac arrest/VF episodes (mean BP < 40 mmHg) in 8 men and 3 women mean age = 42 ± 24 years, mean left ventricular ejection fraction = 39%) undergoing defibrillator (ICD) implant for ventricular tachycardia or previous cardiac arrest were evaluated with continuous ETCO monitoring during defibrillation threshold testing. All patients but one were intubated. Results: Significant differences(P < 0.001)were noted between ETCO values prior (mean 37.2 ± 6.8 mmHg) versus during VF (mean 27.1 ± 5.9 mmHg), and during VF versus return of spontaneous circulation (mean 36.6 ± 6.6 mmHg). ETCO decreased by 23%± 8% from pre-VF to during VF. It increased by 37%± 16% during VF to return of spontaneous circulation. These changes were significantly different(P < 0.001). Conclusion: Significant changes in ETCO were measured during VF arrest. ETCO can predict acute cardiac arrest in a quantitative manner. (PACE 2003; 26[Pt. II]:515–517)

Background and Purpose— The diversity of available outcome measures for acute stroke trials is challenging and implies that the scales may be imperfect. To assist researchers planning trials and to aid interpretation, this article reviews and makes recommendations on the available choices of scales. The aim is to identify an approach that will be universally accepted and that should be included in most acute trials, without seeking to restrict options for special circumstances. Methods— The article considers outcome measures that have been widely used or are currently advised. It examines desirable properties for outcome measures such as validity, relevance, responsiveness, statistical properties, availability of training, cultural and language issues, resistance to comorbidity, as well as potential weaknesses. Tracking and agreement among outcomes are covered. Results— Typical ranges of scores for the common scales are described, along with their statistical properties, which in turn influence optimal analytic techniques. The timing of recovery on scores and usual practice in trial design are considered. Conclusions— The preferred outcome measure for acute trials is the modified Rankin Scale, assessed at 3 months after stroke onset or later. The interview should be conducted by a certified rater and should involve both the patient and any relevant caregiver. Incremental benefits at any level of the modified Rankin Scale may be acceptable. The modified Rankin Scale is imperfect but should be retained in its present form for comparability with existing treatment comparisons. No second measure should be required, but correlations with supporting scales may be used to confirm consistency in direction of effects on other measures.

Human AF may be sustained by localized electrical rotors or focal sources. However, multiple concurrent sources may exist for AF in any patient, that impact the strategy for targeted ablation (Focal Impulse and Rotor Modulation, FIRM). We identified clinical factors influencing the number of

The "aurelia" group of the genus Paramecium (Wichterman 1986) contains three major species-complexes of slipper-shaped organisms. P. aurelia is generally distinguishable from P. caudatum and P. multimicronucleatum on the basis of size (120 ,um-180 ,um length) and its possession of two vesicular micronuclei (approximately 3.5 ,um in diameter). Distinguishing between P. caudatum and P. multimicronucleatum is more difficult because of overlapping size ranges (P. c.: 170 ,um300 pkm long; P. m.: 180 ,um-350 gm long). P. caudatum has one compact micronucleus (8,um-14,um in diameter) and P. multimicronucleatum has between four and eight vesicular ones (0.7 ,m-5 gm in diameter). P. jenningsi is a more recently described member of the "aurelia" group; it has two micronuclei which are larger than those of P. aurelia. Persons without extensive experience in observing members of these species-complexes of Paramecium are inclined to consult How to Know the Protozoa (ahn et al. 1979; Jahn & Jahn 1949). The first revised edition (ahn & Jahn 1949, p. 188) gives directions for distinguishing these species-groups on the basis of micronuclear staining

Few studies are available on magnetic navigation system (MNS) for coronary artery disease. The present investigation was conducted to evaluate the feasibility and safety of guidewire navigation with a MNS in diseased coronary arteries.Between February 2004 and August 2005, a total of 59 patients (68 target vessels) underwent magnetic-assisted guidewire navigation in coronary arteries with stenoses amenable to coronary intervention. Patients were excluded if any of the following conditions applied: pacemakers or cardioverter defibrillator implanted; acute myocardial infarction; thrombotic lesions; chronic total occlusion; claustrophobia; and renal dysfunction with serum creatinine2.5mg/dl. Procedural success was defined as successful guidewire passage distal to the stenoses with no procedural events, defined as either perforation or dissection. Magnetic guidewires successfully crossed 60 (88%) lesions. Only 1 patient experienced a minor dissection of vessel wall in a circumflex lesion and was treated with a coronary stent. There was no other complication related to the magnetic guidewire. Nineteen (27.3%) coronary interventions were performed with magnetic guidewires. In 4 complex lesions (a lesion located in saphenous vein graft with proximal severe tortuosity; 3 approaches to stent-jailed side branch), where conventional wires failed to cross the culprit lesions, magnetic navigation achieved successful guidewire passage.Guidewire navigation using a MNS was feasible and safe. In the four complex cases, magnetic navigation enabled crossing of lesions in which conventional attempts failed. Further studies are needed to better evaluate the efficacy of MNS compared with conventional manual navigation.

Background: The current standard for cardiopulmonary resuscitation (CPR) and automated external defibrillator (AED) retraining for laypersons is a four-hour course every two years. Others have documented substantial skill deterioration during this time period. Objectives: To evaluate 1) the retention of core CPR and AED skills among volunteer laypersons and 2) the time required to retrain laypersons to proficiency as a function of time since initial training. Methods: This was an observational follow-up study evaluating CPR and AED skill retention and testing/retraining time up through 17 months after initial training. The study took place at 1,260 facilities recruited by 24 North American clinical research centers, and included 6,182 volunteer laypersons participating in the Public Access Defibrillation (PAD) Trial. Training to proficiency in either CPR only (N= 2,426) or CPR+AED (N= 3,756) was followed by testing/retraining provided three to 17 months later. Retraining was done in brief, one-on-one, individualized, interactive sessions. The outcome studied was instructors' global assessments of performance of CPR and AED skill adequacy, i.e., whether CPR actions would likely result in perfusion (yes/no) and whether AED actions would result in a shock through the heart (yes/no). Results: For global CPR performance, 79%, 73%, and 71% of volunteers tested for the first time since initial training three to five, six to 11, and 12 to 17 months after initial training, respectively, were judged by their instructors as having adequate performance (p < 0.001, chi-square for linear trend). For global AED performance, 91%, 86%, and 84% of volunteers, respectively, were judged as having adequate performance (p < 0.001). The mean (± standard deviation) times required to test and retrain volunteers to proficiency were 5.7 (± 4.0) minutes for CPR skills and 7.7 (± 4.6) minutes for CPR+AED skills. Conclusions: Among PAD Trial volunteer laypersons participating in a simulated resuscitation, the proportions of volunteers judged by instructors to have adequate CPR and AED skills demonstrated small declines associated with longer intervals between initial training and subsequent testing. However, based on instructors' judgment, large majorities of volunteers still retained both CPR and AED core skills through 17 months after initial training. Furthermore, individual testing and retraining for CPR and AED skills were usually accomplished in less than 10 minutes per volunteer. Additional research is essential to identify training and evaluation techniques that predict adequate CPR and AED skill performance of laypersons when applied to an actual cardiac arrest.

Background The Public Access Defibrillation (PAD) Trial was a randomized, controlled trial designed to measure survival to hospital discharge following out-of-hospital cardiac arrest (OOH-CA) in community facilities trained and equipped to provide PAD, compared with community facilities trained to provide cardiopulmonary resuscitation (CPR) without any capacity for defibrillation. Objectives To report the implementation of community-based lay responder emergency response programs in 1,260 participating facilities recruited for the PAD Trial in the United States and Canada. Methods This was a descriptive study of the characteristics of participating facilities, volunteers, and automated external defibrillator (AED) placements compiled by the PAD Trial, and a qualitative study of factors that facilitated or impeded implementation of emergency lay responder programs using focus groups of PAD Trial site coordinators. Results The PAD Trial enrolled 1,260 community facilities (14.8% residential), with 20,400 lay volunteers (mean +/- standard deviation = 13.4 +/- 10.7 per facility) trained to respond to OOH-CA. The 598 locations randomized to receive AEDs required 2.7 +/- 1.8 AEDs per facility. Volunteer attrition was high, 36% after two years. Barriers to recruitment and implementation included identification of appropriate "at-risk" facilities, lack of interest or fear of litigation by a facility key decision maker, lack of motivated potential volunteer responders, training and retraining resource requirements, and lack of an existing communication/response infrastructure. Conclusions These data indicate that implementation of community-based lay responder programs is feasible in many types of facilities, although these programs require substantial resources and commitment, and many barriers to implementation of effective PAD programs exist.

Pulmonary vein (PV) isolation using radiofrequency (RF) ablation can induce PV stenosis. Cryoablation may offer a safer alternative energy source for PV isolation. PV isolation with cryoablation was attempted in 31 patients with paroxysmal atrial fibrillation (AF). Event monitors were used to measure the AF episode burden. Serial spiral CT scans were obtained to monitor PV stenosis pre- and postcryoablation. Cryoablation was immediately successful for PV isolation in 29 of 31 patients (94%), with 5.9 +/- 1.2 months of follow-up. Additional RF ablation was performed for AF recurrences in seven patients. The remaining 22 patients with a single cryoablation procedure demonstrated a time-dependent, long-term reduction in the frequency of AF episodes. At 6 months of follow-up, 18 of 22 of cryo-treated only patients (82%) were free of symptomatic AF episodes, and antiarrhythmic drugs were discontinued in 12 of 22 patients. Serial spiral CT scans demonstrated no change in the cryo-treated PV ostial diameter. PV cryoablation was effective to control paroxysmal AF in most patients. Early recurrences of AF postcryoablation were common, though tended to resolve within 6 months postablation, consistent with a process of reverse atrial remodeling. Cryoablation of the PVs did not cause PV stenosis or other serious adverse events.

We sought to evaluate prospectively the safety and efficacy of cryothermal energy to ablate typical atrial flutter (AFL). Ablation of cardiac tissue using cryothermal energy has recently been developed as an alternative to radiofrequency energy, which may offer certain advantages in the treatment of AFL. This prospective, multicenter nonrandomized study of a new catheter-based system for the treatment of cavotricuspid isthmus (CTI)-dependent AFL enrolled patients between 18 and 75 years of age. The CTI dependence of AFL was confirmed at electrophysiologic study with activation mapping and/or entrainment. Patients with atrial septal defect, recent myocardial infarction, left ventricular ejection fraction

This pilot study was performed to assess the use of cardiac troponin I to predict respiratory failure in children admitted to the hospital with respiratory syncytial virus (RSV) infections. We enrolled a prospective convenience sample of children under 5 years of age who were admitted to our university-based, tertiary care children's hospital from December 1, 2000, to February 1, 2002, with RSV infections. A cardiac troponin I was drawn at admission. We assessed the test characteristics for positive cardiac troponin I (defined as >0.3 ng/mL, the manufacturer's upper limit of normal) in correctly identifying children who had respiratory failure as evidenced by the need for endotracheal intubation. Twenty-five children from 9 days to 38 months of age were included. Ten children had a positive cardiac troponin I and 3 of these children had respiratory failure. A positive cardiac troponin I demonstrated a sensitivity of 100%, specificity 68%, positive predictive value of 30%, negative predictive value of 100%, and accuracy of 72%. The area under the receiver operating characteristic curve was 0.939 (95% confidence interval, 0.820-1.0), suggesting a high degree of discriminatory power in selecting children with respiratory failure. A sample size calculation revealed that a follow-up study of 359 patients is needed before the clinical use of cardiac troponin I for this purpose.

Background: Myocardial dysfunction occurs immediately after successful cardiac resuscitation. Our purpose was to determine whether measurement of cardiac troponin I in children with acute out-of-hospital cardiac arrest predicts the severity of myocardial injury. Methods and results: This prospective, observational study was performed in the Pediatric Intensive Care Unit (PICU) on 24 patients following arrest, ranging in age from 8 months to 17 years. Troponin measurements were obtained on admission, and at 12, 24, and 48 h. Transthoracic echocardiograms were performed within 24 h after admission. Survival to hospital discharge was 29% (7/24). The mean age was 5.9±4.6 years for survivors and 4.2±5.3 years for non-survivors. The median (range) duration of cardiac arrest times for survivors was 6 min (3 to 63 min) versus 34 min (4 to 70 min) for nonsurvivors ( P =0.02). Survivors received 1.3±2.2 doses of epinephrine (adrenaline) compared with 2.9±1.6 doses for non-survivors ( P =0.02). Only one patient had ventricular fibrillation and defibrillation was unsuccessful. The ejection fraction for survivors averaged 73.2±11.2%, but for nonsurvivors only 55.4±19.8% ( P =0.04). Ejection fraction correlated inversely with troponin at 12 h ( r =−0.54, P =0.01) and at 24 h ( r =−0.59, P =0.02). Circumferential fiber shortening for survivors was 37.5±7.8 and 25.5±10.7% for nonsurvivors ( P =0.02). It also correlated inversely with troponin ( r =−0.46, P =0.03 for survivors and r =−0.65, P =0.01, for nonsurvivors). Conclusion: After cardiac arrest and resuscitation in pediatric patients, the severity of myocardial dysfunction was reflected in troponin I levels.

Sudden cardiac arrest (SCA) is the leading cause of death in the United States and industrialized nations. In North America, the annual incidence of out-of-hospital SCA is over 0.55 per 1,000 population1 such that 164,000 to 300,000 out-of-hospital arrests occur annually.2 However, despite advances in recent decades, clinical outcomes from out-of-hospital SCA remain dismal, and survival to hospital discharge ranges from 4% to 13%.3–5 Clearly, improving the management of out-of-hospital SCA is a major public health issue. In 2005, the American Heart Association (AHA) substantially revised the previous guidelines for cardiopulmonary resuscitation (CPR) and emergency cardiac care for SCA, which were published in 2000. In particular, new CPR codified the primary importance of uninterrupted mechanical chest compression, given provocative preclinical6 and clinical7 studies showing the benefits of this approach even without mouth-to-mouth respiration or assisted ventilation. Accordingly, the revised guidelines reduced the recommended number of breaths per CPR cycle but did not advocate elimination of assisted ventilation because of concerns including the generalizability of these results.8 New CPR also codified recent evidence that chest compressions are more effective when performed together with an impedance threshold device (ITD), which improves chest recoil, reduces intrathoracic pressure, and augments venous return.9 The rationale behind the numerous other changes to new CPR are described in the parent document.5 In this issue of Heart Rhythm, Aufderheide et al10 studied whether implementation of these new CPR guidelines improved outcomes in 1,605 victims of out-of-hospital SCA in five emergency medical service systems (EMS) in the United States, compared with 1,641 historical controls at these centers treated per the 2000 guidelines in the immediately preceding years. The primary endpoint was survival to hospital discharge, and secondary endpoints were the return of spontaneous circulation (ROSC), survival to hospital discharge based on initial cardiac arrest rhythm, and neurological status at time of discharge assessed by the cerebral performance score (CPS). The authors found a significant 30% relative increase (from 10.1% to 13.1%) in survival to hospital discharge and increased rate of ROSC (from 30.3% to 33.8%) in patients treated by new CPR compared with the 2000 guidelines. As expected, results varied markedly by presenting rhythm: survival to hospital discharge was 32% versus 20% in patients with ventricular tachycardia/ventricular fibrillation (VT/VF; new CPR versus prior guidelines; P

We report a case of atrial tachycardia masquerading as atrial flutter in a man who had previously undergone catheter ablation for atrial flutter. The recurrent arrhythmia was electrocardiographically almost identical to the prior atrial flutter; at repeat electrophysiologic study, although bidirectional conduction block was observed in the tricuspid annulus-inferior vena caval isthmus, the atrial arrhythmia was readily initiated. Activation mapping suggested typical atrial flutter, but entrainment techniques demonstrated intra-atrial reentry not involving the ablated isthmus. This case illustrates the need to apply entrainment techniques even in cases of apparent "typical" atrial flutter to confirm that putative ablation targets are necessary for tachycardia perpetuation.

BackgroundRadiofrequency catheter ablation is standard treatment for children with re-entrant supraventricular tachycardias. Autonomic changes have been noted after such ablation for atrioventricular nodal re-entry tachycardia, but not as well documented with atrioventricular re-entry over an accessory pathway.Methods and resultsIn 10 normal paediatric volunteers and 12 children referred for electrophysiologic testing and radiofrequency ablation of supraventricular tachycardia, non-invasive autonomic function tests and tilt-table testing were performed, and the variability in 24-h heart rate was analysed. Patients with supraventricular tachycardia underwent these tests both 24–72 h before and 24 h after ablation. Patients with tachycardia underwent additional autonomic testing to assess the sensitivity of baroreceptors and the intrinsic heart rate with autonomic blockade immediately before and after ablation. One non-invasive autonomic function test, namely handgrip, demonstrated significant differences (p < 0.05) in diastolic blood pressure before and after ablation, though these values did not differ from controls. Significant decreases were noted in two indexes of the variability of heart rate before and after ablation (p < 0.05). Certain tilt test variables also demonstrated significant differences between controls and those with tachycardia subsequent to ablation. Intracardiac testing demonstrated changes (p < 0.05) in sinus cycle lengths, effective refractory periods and/or blood pressures at baseline and during testing of the sensitivity of baroreceptors before and after ablation. These changes were consistent with increased sympathetic or decreased parasympathetic tone. With autonomic blockade, these differences were abolished.ConclusionsCatheter ablation of accessory pathways in children was associated with changes consistent with increased sympathetic or decreased parasympathetic tone. These autonomic changes persisted 24 h after the ablation procedure.

Background: Nesiritide (synthetic B-Natriuretic Peptide) has been shown to improve symptoms and hospitalization in adult patients with severe heart failure via a variety of mechanisms including enhanced diuresis. The major side effect precluding use is hypotension. This medication has not been evaluated in pediatric patients. The objective of this study is to review the use of nesiritide in a severely ill group of pediatric patients.Methods: This study reviews 10 uses of nesiritide in seven pediatric patients (ages 20 35 months old all but one less than 18 months old) who were awaiting cardiac transplantation due to severe congenital heart disease (6) or dilated cardiomyopathy (1). All patients were classified as Status IA on multiple inotrope infusions and diuretics. The study evaluated the effects of nesiritide on blood pressure and urine output values from the day prior to infusion to the final day of the infusion. All values are presented as mean S.D. with Student’s t-testing for statistical significance. Results: Nesiritide was infused for a 10.6 4.1 days at doses of 0.005 to 0.02mcg/kg/min. In one use, the infusionwas discontinued due to concern of hypotension (no significant change from the day prior to infusion on retrospective review). This patient’s infusion was resumed in 2 days. Infusions were continued until subjective patient improvement or cardiac transplant. Urine output (ml/kg/hr) improved by 24% (p 0.05) from preto duringnesiritide (pre 2.6 1.3 vs. during 3.6 1.6). Total urine output (ml) improved by 22% (p 0.05). The figure shows urine output changes with each infusion. There were no changes (p NS) in daily highest and lowest systolic blood pressure related to nesiritide infusion (pre high SBP 102 14 mmHg vs. post high 101 10; pre low SBP 78 11 vs. post low 74 10). Five of the seven patients received cardiac transplantation while two others clinically improved enough to discontinue nesiritide. No other adverse effects of nesiritide were noted. Conclusion: Nesiritide improves urine output without significant hypotension or other adverse effects in severely ill pediatric patients.