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PubMed2000

Unipolar electrogram characteristics predictive of successful radiofrequency catheter ablation of accessory pathways.

INTRODUCTION: The purpose of this study was to determine the characteristics of the unipolar electrogram that are most helpful in predicting successful radiofrequency ablation of accessory pathways. METHODS AND RESULTS: The unipolar electrogram was analyzed at 185 ablation sites in 53 patients; 94 attempts were directed at the site of earliest atrial activation ("atrial group") and 91 at the site of earliest ventricular activation ("ventricular group"). The electrogram was analyzed for several features, including pattern ("QS" or "initial R"). Unipolar pattern: Overall, a "QS" pattern was seen at 55% of unsuccessful, 75% of temporarily successful, and 90% of permanently successful sites. For the atrial group, the respective frequencies were 53%, 77%, and 92%, and for the ventricular group, 57%, 73%, and 86%. The difference in pattern distribution between unsuccessful and permanently successful sites was significant for all groups: overall, P < 0.0001; atrial group, P = 0.0005; ventricular group, P = 0.02. Absence of a "QS" pattern (i.e., "initial R") predicted a 92% chance of unsuccessful ablation. Additional features: Activation times were significantly shorter at permanently successful than at unsuccessful (P < 0.0001) or temporarily successful sites (P = 0.0002). No significant differences were found in atrial or ventricular amplitudes or in A/V ratios. Intrinsic deflection slew was lower at temporarily successful sites (P = 0.03 vs all other sites). CONCLUSION: Ablation at sites revealing an "initial R" pattern (i.e., absent "QS") is very unlikely to be successful. Activation time is shorter at successful sites. These features are equally applicable when mapping the atrial potential as when mapping the ventricular potential.

Adolescent↗
PubMed1994

Radiofrequency ablation of slow pathway in patients with atrioventricular nodal reentrant tachycardia. Do arrhythmia recurrences correlate with persistent slow pathway conduction or site of successful ablation?

BACKGROUND: Residual slow pathway conduction in the form of persistent jump in the atrioventricular (AV) conduction time or atrial echo beats is a common finding after successful radiofrequency (RF) ablation of the slow pathway in patients with AV nodal reentrant tachycardia (AVNRT). Sites of successful RF ablation of the slow pathway may be located anteriorly in the tricuspid annulus (cephalad to the coronary sinus os) or posteriorly (at, within, or caudal to the coronary sinus os). The aim of this study was to investigate whether arrhythmia recurrences correlate with persistent slow pathway conduction or site of successful ablation. METHODS AND RESULTS: Among 55 patients with symptomatic AVNRT having RF ablation, 23 patients (42%) (group 1) had evidence of persistent dual AV nodal pathway physiology and/or echo beats, whereas in 32 patients (group 2), slow pathway conduction had been completely eliminated. With regard to ablation sites, 14 patients (25%) (group A) had their slow pathway successfully ablated at an inferoposterior site, whereas in 41 patients (group B), the ablation site was located anteriorly to the coronary sinus os. The study patients included 17 men and 38 women, aged 37 +/- 18 years. The electrophysiological study and RF ablation were performed in a single session in 50 patients (91%). After the first session, the technique was successful in all patients (100%), with elimination of AVNRT and without affecting AV conduction. A mean of 9 +/- 6 lesions were applied. The total procedure time averaged 4 +/- 1 hours. Fluoroscopy time was 41 +/- 25 minutes. Except for transient AV block in 1 patient, no other complications occurred. Over 12 +/- 8 months, a total of 7 patients (13%) had recurrence of AVNRT, and 6 of them underwent successful repeat slow pathway RF ablation. Recurrence rate was 9% (2 patients) for group 1, with persistent jump or echo beats, and 16% (5 patients) for group 2, without residual slow pathway conduction (P = NS). Five of the recurrences (71%) were noted in group A and 2 in group B. Thus, the recurrence rate was 36% for group A (5 of 14 patients), with posterior ablations, and 5% for group B (2 of 41 patients), with anterior sites of successful RF ablation (P < .05). CONCLUSIONS: After successful RF ablation of the slow pathway in patients with AVNRT, residual slow pathway conduction does not correlate with clinical tachycardia recurrences. However, the site of successful RF ablation of the slow pathway does correlate with arrhythmia recurrences. More recurrences are observed when the site is located inferoposteriorly, at or below the os of the coronary sinus, as compared with medial and anterior locations of the ablation site.

Adolescent↗
PubMed1999

Compliance of the respiratory system as a predictor for successful extubation in very-low-birth-weight infants recovering from respiratory distress syndrome.

OBJECTIVE: To develop additional criteria to predict for successful extubation of very-low-birth-weight infants recovering from respiratory distress syndrome. DESIGN: Prospective study. SETTING: Neonatal intensive care unit at a university teaching hospital. INTERVENTIONS: Infants ready for extubation according to clinical, ventilatory and blood gas criteria were studied. Before extubation, tidal volume (Vt), minute ventilation, respiratory rate/Vt and mean inspiratory flow were measured during two different ventilatory settings: (i) during intermittent mandatory ventilation (IMV); and (ii) while breathing spontaneously with endotracheal continuous positive airway pressure (CPAP). Tidal volume was obtained through electronically integrated flow measured by a hot-wire anemometer. Total respiratory compliance (Crs) was determined during IMV and was derived from the formula Vt/PIP-PEEP, where the difference between peak inspiratory pressure (PIP) and positive end-expiratory pressure (PEEP) represented the ventilator inflation pressure. MEASUREMENTS AND MAIN RESULTS: Each of 49 infants was studied once before extubation. 33 infants (67%) were successfully extubated and 16 (32.6%) required reintubation. Infants in the success and failure groups were matched for gestation, post-conceptional age, study weight and methylxanthine therapy at the time of study. Successful extubation was associated with a higher mean absolute Crs value (ml/cm H2O) specific Crs value (standardised for body length; ml/cm H2O/cm) compared with infants in whom extubation failed (0.67 v. 0.46; P = 0.01 and 0.018 v. 0.014; P = 0.03, respectively). Analysis of ROC curves detected thresholds for Crs (0.5 ml/cm H2O) and Vt (7 ml) for predicting successful extubation. An absolute Crs value 0.5 ml/cm H2O or more improved the likelihood of successful extubation when compared with clinical/ventilator and blood gas criteria. The likelihood of successful extubation was 81% if the Crs value was > or = 0.5 ml/cm H2O. A tidal volume of 7 ml or more was less sensitive in contributing to successful extubation (sensitivity 69%). The major causes for extubation failure included atelectasis (diffuse and/or localised) and the presence of a patent ductus arteriosus. CONCLUSIONS: In addition to following very precise ventilatory criteria for extubation, we found that bedside measurement of total respiratory system compliance added to the likelihood of extubation success in infants recovering from respiratory distress syndrome. Prospective studies are needed to validate the findings of this study.

Aminophylline↗
PubMed2005

[Dynamics of soil properties under secondary succession forest communities in Mt. Jinyun].

Mt. Jinyun is located in the north suburb of Chongqing, 30 km away from the city center. It is rich in forest plants, an epitome of forests in north tropical areas of China. Under anthropocentric disturbance, there still exist large numbers of succession communities, and the process of successive development follows the way of shrub-grassland (X1)-->coniferous forest (X2)-->coniferous-broad leaved mixed forest (X3)-->evergreen broad-leaved forest (X4). By now, soil and water conservation is very important in the Three Gorges area of Yangtze River, and the investigation on the secondary succession of the forests could help to realize the changes of the forests and soils under anthropocentric disturbance, and supply information on the protection of natural forests and the artificial reforestation of this area. In this paper, some typical and representative plant communities in different succession stages were selected to study the plant composition and type and the soil properties, with species diversity indices and canopy density investigated in many standard squares and soil physical and chemical characteristics analyzed. The results showed that there were obvious variations of soil properties with time. As the plant community developed from primary stage to climax, the contents of soil organic matter, total N, and available N and K increased in order of X1 < X2 < X3 < X4, soil pH changed from 5.23 (X1) to 4.06 (X4), soil base saturation varied from 58.3% (X1) to 37.7% (X4), and soil CEC increased with the succession. It was suggested that an intense soil acid leaching was occurred in Mt. Jinyun. The contents of soil organic matter and total N in different layers showed a trend of A>B>C, e. g., soil total nitrogen in evergreen broad leaved forest was 2.31(A), 0.66(B) and 0.12(C)g x kg(-1). Gray analysis was used to study the relationships of soil properties between the climax community and other three succession communities. The relation coefficient was 0.461 0 (X3), 0.586 2(X2) and 0.6821 (X1), respectively, indicating that soil nutrients were accumulated as the forest succession community progressed. The plant arbor species followed the sequence of 0 (X1) < 7.5 (X2) < 9.0 (X3) < 12.8 (X4), and the canopy density ranked as the same way. Plant community could affect soil nutrient reserves significantly. Multivariate variance analysis showed that soil properties varied significantly among different seasons, but this variation had no impact on the community replacement and soil development during the chronosequence of community succession. The variation of soil properties adapted well to each successive community.

China↗
PubMedDate not supplied

Correlates of expected success at health habit change and its role as a predictor in health behavior research.

Perceived ability to change health habits successfully is undoubtedly an important factor underlying personal health behavior. This report examines expected success in changing future habits, using a sample of community-resident adults 18-65 years of age (n = 1,367). One set of analyses used expected success as a dependent variable, whereas another set used it as an independent variable for health behavior and knowledge indices. In the dependent variable analysis, results showed that reported past success at health habit change was the strongest predictor of success expected in the future. Optimism about future success was also associated with variables that already placed individuals at an advantage to change behavior (e.g., not smoking, regular exercise, lower Body Mass Index, support in the family). When used as a predictor variable, expected future success was not associated with five health-related, self-report indices of behavior, knowledge, and perceived risk. Further examination showed, however, that in three instances the association between expected success and the outcome indices seemed to plateau in the most optimistic group. Extreme optimism (that admits no chance of failure) may be a belief characteristic that deserves further investigation, one that will present a challenge to research and practice. Men tended to report greater expected future success than women, although women had more favorable reports on three of the five health-related behavior/knowledge indices.

Adolescent↗
PubMed1992

Defining and predicting tracheoesophageal puncture success.

There is considerable variability in the reported success rates of tracheoesophageal puncture due, in part, to the lack of a clear definition of success and a paucity of knowledge about factors that determine success. In this article, we define success on a continuum with the use of a 15-point rating scale that incorporates aspects of use and quality of speech and ability to care for the fistula and prosthesis. We suggest a cutoff score for functional and nonfunctional speakers. We define immediate and short- and long-term success. Variables related to the patient, clinician, surgical procedure, and extent of disease were subjected to a multiple regression analysis to determine which predicted success. Overall success was predicted by greater clinician expertise, younger patient age, and better patient health. We discuss the use of the rating scale and an equation to predict success.

Adult↗
PubMed2006

Factors affecting technical success of fetal aortic valve dilation.

OBJECTIVE: We have reported previously that valve dilation enhances growth of cardiac structures and may prevent hypoplastic left heart syndrome (HLHS) in fetuses with critical aortic stenosis. We aimed to investigate maternal/fetal factors which may affect the technical success of fetal valvuloplasty, and to describe perinatal complications of the procedure. METHODS: This was a descriptive series of 22 fetuses diagnosed with critical aortic stenosis developing into HLHS which underwent intervention by valvuloplasty. Initially this was attempted using a percutaneous approach; reassessment after our first five attempts, only one of which was successful, led to the introduction of the option of laparotomy. Technical success was defined as balloon inflation across the aortic annulus and a broader jet through the aortic valve as assessed by Doppler. Data collected included body mass index, demographic variables, ultrasound findings and postprocedure interventions. RESULTS: Technical success increased significantly if maternal laparotomy was an option (83.3% vs. 20.0%, P = 0.017). Laparotomy was performed in 66.6% (12/18) of cases. There was a learning curve that showed an increase in success rate and decrease in need for laparotomy over the 3-year study period. Neither the need for laparotomy nor the chances of technical success were predictable by gestational age, body mass index or placental location. Tocolysis was limited to perioperative prophylaxis; one woman experienced wound infection and fluid overload. Postoperatively, three fetuses died and two delivered prematurely, 2 and 7 weeks after intervention. CONCLUSION: Fetal aortic valvuloplasty can be performed with technical success, with low fetal loss rate and few maternal complications. While the need for laparotomy cannot be predicted, having it available as an option improves the technical success rate.

Adult↗
PubMed1994

Thrombolysis in acute peripheral arterial occlusion: predictors of immediate success.

Thrombolytic therapy is frequently used for the treatment of peripheral arterial occlusion, but clinical predictors of success have not yet been defined. We prospectively evaluated 80 consecutive patients receiving intra-arterial urokinase for acute (< 14 days) ischemia. Fifty-five patients (69%) were treated for bypass graft occlusion and 25 patients (31%) for native arterial occlusion. Two primary outcome measures were evaluated using multivariate techniques (stepwise logistic regression) to determine the independent predictors of immediate arteriographic success: successful (> 80%) thrombolysis and avoidance of adjuvant operative or endovascular procedures. Independent variables examined included age, sex, comorbid conditions, severity, duration, etiology and location of the ischemic process, and positioning of the infusion catheter and guidewire. Overall, successful lysis was achieved in 57 patients (71%) and adjuvant procedures were avoided in 22 patients (28%). Successful outcome was more frequent in prosthetic graft (78%) and native arterial (72%) occlusions than in vein graft occlusions (53%, p = 0.017) and in nondiabetics than in diabetics (80% vs. 52%, p = 0.031). Lysis was dependent on placement of the catheter into the substance of the thrombus (85% vs. 0% success, p = 0.004) and passage of a guidewire through the occlusive process (92% vs. 10% success, p = 0.001). The only parameter independently predictive of successful outcome without the use of adjuvant procedures was the location of the occlusion; additional procedures were necessary in 88% of aortoiliac and 82% of infrainguinal occlusions vs. only 17% of upper extremity occlusions (p = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1994

[Axillary blockade of the brachial plexus. A prospective study of blockade success using electric nerve stimulation].

Axillary block is a common anesthetic technique for operations on the hand and forearm. In our hospital, with many trainees in anaesthesia, only 250-300 axillary blocks per year are performed by about 30 colleagues. This implies a small number of blocks for each anaesthetist. The present study was designed to assess whether it is possible to teach this technique and use it with an adequate degree of success under these conditions. We used a nerve stimulator and studied whether the success of the block under these conditions is independent of anaesthetist's experience in this technique. Furthermore, we examined other factors involved in the success of the block. METHODS. The study included 112 patients subjected to elective surgery of the upper extremity; all received an axillary block. We used a nerve stimulator and injected mepivacaine 1% without adrenaline. The following parameters were recorded: the number of blocks to date performed by the anaesthetist; the minimal current required for nerve stimulation; the dose of local anaesthetic; the time between the end of injection and the beginning of surgery; the quality of sensory and motor blockade after 10, 20, and 30 min. Sensory blockade was assessed by the pinprick method (no blockade, analgesia, anaesthesia); motor blockade was judged by comparing the muscle strength of both arms (no blockade, paresis, paralysis). Data were analyzed using the Mann-Whitney test, with P < 0.05 considered statistically significant. RESULTS. Of the 112 blocks, 95 (85%) were successful; 17 (15%) failed and the patients required general anaesthesia. Eight of the successful blocks showed a decrease in analgesic quality after > or = 70 min and required additional analgesics or general anaesthesia. We found no correlation between the experience of the anaesthetist and the success of the block. The minimal required current for nerve stimulation in the success group was 0.4 mA and differed significantly from the value of 0.6 mA in the failure group (Table 3). The dose of mepivacaine was higher in the success group (5.9 vs. 5.3 mg/kg). Complete sensory blockade was more frequently achieved for the median, ulnar, and radial nerves than for the musculocutaneus and cutaneous brachii medialis (Fig. 3). The frequency of complete sensory blockade (anaesthesia) had increased by 21.9% between the 20th and 30th min. Complete motor blockade was less often achieved than sensory blockade (Fig. 4). CONCLUSIONS. Using the method of electrostimulation, the axillary block is an appropriate anaesthetic technique that can be applied in a hospital where each anaesthetist only occasionally performs it. Prior to injection of the local anaesthetic, the current for nerve stimulation should be reduced to < 0.5 mA. The time between the end of injection and the beginning of surgery should be no less than 30 min because complete sensory blockade can more often be achieved. The dose of mepivacaine should be no less than 6 mg/kg body weight.

Adolescent↗
PubMed1989

Predictors of success in percutaneous transluminal coronary angioplasty of chronic total occlusions.

Earlier studies have indicated that percutaneous transluminal coronary angioplasty (PTCA) of chronic total occlusions has a low success rate. To determine success rate and assess clinical and angiographic variables associated with success and complications, 57 total occlusions in 56 patients undergoing PTCA were analyzed. The clinical duration of occlusion was 51 +/- 86 days. Success (less than 50% residual stenosis) was achieved at 40 of 57 (70%) dilatation sites. Of these 57 total occlusions, 5 were attempted within 24 hours of acute myocardial infarction, 35 between 1 day and 8 weeks of clinical occlusion, 13 greater than 8 weeks and 4 were of unknown duration. Success rates were 4 of 5, 25 of 35, 9 of 13 and 2 of 4, respectively, in each group (difference not significant, comparison of all time groups). Of the 9 narrowings with a successful PTCA for an occlusion greater than 8 weeks, the mean duration of occlusion was 93 +/- 41 days (range 60 to 180). None of the attempted dilatations of occlusions with a clinical duration of greater than 180 days (n = 3) was successful. None of the clinical or angiographic variables (including tortuosity, length of occlusion gap, distance of the occlusion from the vessel origin, thrombus, lesion calcium, collaterals, prior myocardial infarction, vessel dilated or diffuse disease) impacted on success rate (difference not significant for all). No patient died, had a Q-wave infarction, required emergency coronary artery bypass grafting or underwent repeat PTCA within 7 days of the procedure. Non-Q-wave infarction occurred in 2 of 56 patients (4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Effect of successful angioplasty following thrombolysis on infarct size and left ventricular function.

The role of the angioplasty following thrombolysis in acute myocardial infarction has been discussed in several studies, however the effect of successful angioplasty on infarct size and left ventricular function has not been properly evaluated. Successful reperfusion was achieved in 79 out of 104 patients with primary anterior acute myocardial infarction. These patients were classified as follows, according to the type of intervention during the acute phase: 50 patients in which thrombolysis was successful (the thrombolysis group); 12 patients who underwent successful immediate angioplasty following successful thrombolysis (the immediate angioplasty group); and 17 patients in which rescue angioplasty was successful (the rescue angioplasty group). The 25 patients whose infarct-related vessels were not reperfused after intervention were classified as the non-reperfused group. Infarct size, evaluated as defect volume by T1-201 SPECT, 1 month after the onset, was 840 +/- 154 units (mean +/- S.D.) in the immediate angioplasty group and was similar to that in the thrombolysis group (948 +/- 88 units), but significantly smaller than in the non-reperfused group (1759 +/- 108 units). There were no significant differences in left ventricular function in the immediate angioplasty group and the thrombolysis group. Successful rescue angioplasty did not have any beneficial effect on left ventricular functions or infarct size, when compared with the failed thrombolytic group (1105 +/- 169 units vs. 1617 +/- 169 units). End-diastolic volume (52 +/- 3 ml/m2) in the successful rescue angioplasty group, however, was significantly smaller than in the failed thrombolysis group (67 +/- 3 ml/m2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1982

Methadone-maintained males' reactions to success and failure: causal attributions, self-efficacy, and attitudes toward heroin.

This exploratory study investigated several components of Marlatt's [1,2] cognitive-behavioral model of relapse to substance abuse. The components were outcome expectancies for the abused substance, self-efficacy, and causal responsibility for success and failure. Also, Hispanic and white ethnic differences in causal attributions were analyzed. Some support was found for Marlatt's model. Both groups exhibited more favorable attitudes toward heroin following success and failure. However, the success group evaluated heroin most favorably. This finding may have been due to both groups responding more to task-performance anxiety than to success and failure. Hispanic subjects attributed success most to the internal cause of high effort and white subjects exhibited lowered self-efficacy by attributing failure most to low ability. Nonsupport for Marlatt's model was found. Success was found not to enhance self-efficacy. White subjects did not take personal responsibility for success. They attributed success most to easy task. A self-protective bias was evident in the Hispanic subjects attributing failure most to hard task. The meaning and implications of these findings, as well as suggestions for further research, are discussed.

Achievement↗
PubMed1993

Importance of electrode design, lead configuration and impedance for successful low energy transcatheter atrial defibrillation in dogs.

OBJECTIVES: We assessed the feasibility of low energy endocardial defibrillation in a canine model of atrial fibrillation, comparing catheters with large surface area electrodes and standard electrode catheters, and evaluated the effects of lead configuration and circuit impedance on defibrillation energy requirements. BACKGROUND: Although recent animal studies have demonstrated the feasibility of low energy endocardial atrial defibrillation, their results have been conflicting with regard to important methodologic aspects. METHODS: In 14 anesthetized greyhounds, atrial fibrillation was induced by rapid atrial pacing and maintained by vagal stimulation. Two large surface area braided electrode catheters and two standard electrode catheters were introduced percutaneously, one of each, in the right atrial appendage and right ventricular apex. A cutaneous patch electrode was placed on the left thorax. Biphasic shocks synchronized to the ventricular electrogram were used to terminate atrial fibrillation. Seven configurations were evaluated. Three used standard electrodes: proximal atrial cathode to distal atrial, ventricular or cutaneous anode. Four used braided electrodes: three with atrial cathode to ventricular, cutaneous or combined anode; one with ventricular cathode to atrial anode. RESULTS: Defibrillation with standard electrode catheters was associated with high impedance (576 +/- 112 omega) and low success rates for all configurations (28% success at < or = 40 J, no successes at 10 J). Low energy defibrillation was readily achieved with the braided electrodes with significantly lower impedance (75 +/- 13 omega, p < 0.0001). Ventricular fibrillation did not occur. The success rate of cardioversion increased in a dose-response manner, allowing fitting of a sigmoid curve and calculation of energy associated with 50% (ED50) and 90% (ED90) success. The most successful configuration was ventricular cathode/atrial anode (ED50 1.5 +/- 0.4 J), and the least successful was atrial anode/cutaneous patch (ED50 6.5 +/- 3.2 J, p = 0.0001). CONCLUSIONS: Low energy atrial defibrillation is feasible using large surface area electrodes but not with standard electrode catheters owing to high impedance. An intracardiac anode provides lower impedance and higher success rates than are provided by a cutaneous anode.

Analysis of Variance↗
PubMed1996

Upper limit of vulnerability is a good estimator of shock strength associated with 90% probability of successful defibrillation in humans with transvenous implantable cardioverter-defibrillators.

OBJECTIVES: The goals of this study were to determine the probability of successful defibrillation at the upper limit of vulnerability and to evaluate a minimal safety margin for implantable cardioverter-defibrillator first shocks based solely on the upper limit of vulnerability. BACKGROUND: The upper limit of vulnerability is the strength at or above which ventricular fibrillation is not induced when a stimulus is delivered during the vulnerable phase of the cardiac cycle. It has been proposed as an estimate of defibrillation efficacy because it correlates with the defibrillation threshold and can be determined with a single episode of fibrillation. METHODS: We studied 40 patients prospectively at implantation of transvenous cardioverter-defibrillators. Defibrillation threshold was defined as the weakest biphasic shock that defibrillated after 10 s of ventricular fibrillation. The upper limit of vulnerability was defined as the weakest biphasic shock that did not induce ventricular fibrillation when given at 0, 20 and 40 ms before the peak of the T wave in ventricular paced rhythm at cycle length 500 ms. After determination of the upper limit of vulnerability and defibrillation threshold, patients underwent six additional fibrillation-defibrillation episodes. The strength of five of the defibrillation shocks was equal to the upper limit of vulnerability; the strength of one of the six shocks was randomly selected to be equal to the upper limit of vulnerability plus 3 J. The implantable cardioverter-defibrillator was tested at the upper limit of vulnerability plus 3 J in 28 patients. RESULTS: The defibrillation threshold was 8.8 +/- 5.0 J (mean +/- SD), and upper limit of vulnerability was 11.3 +/- 4.6 J; the defibrillation threshold and upper limit of vulnerability were highly correlated (r = 0.89, p < 0.001). The success rate for the 200 defibrillation shocks with strength equal to the upper limit of vulnerability was 90% (95% confidence intervals based on proportion of successes in 40 patients: 86% to 94%). All five defibrillation test shocks at the upper limit of vulnerability were successful in 24 patients (60%); four of five were successful in 12 patients (30%); and three of five were successful in 4 patients (10%). All 40 test shocks and 28 implantable cardioverter-defibrillator shocks with a strength equal to the upper limit of vulnerability plus 3 J were successful. CONCLUSIONS: The upper limit of vulnerability is a good estimator of the shock strength associated with 90% probability of successful defibrillation (DFT90). A strength of 3 J above the upper limit of vulnerability is a good estimate of the minimal acute safety margin for implantable cardioverter-defibrillator first shocks.

Adult↗
PubMed2003

Predictors of successful arteriovenous fistula maturation.

BACKGROUND: Understanding the factors associated with successful arteriovenous fistula (AVF) maturation may provide an opportunity to improve vascular access outcomes. METHODS: This prospective cohort study enrolled 348 hemodialysis patients receiving an AVF and followed them until ascertainment of successful AVF maturation. Multivariable logistic regression was used to develop (1) explanatory models of factors associated with AVF success and (2) models for predicting success based on sociodemographic and comorbidity profiles. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the discriminative ability of our predictive model. Predictive probabilities of AVF maturation under the assumption of optimal surgical technique defined by explanatory models were calculated. RESULTS: A total of 55.5% of AVFs successfully matured. A history of stroke or transient ischemic attack, increasing age, and dependence on dialysis at the time of access placement were associated with lower probabilities of maturation. Of potentially modifiable variables, maturation was associated with greater intraoperative doses of heparin, use of large-diameter veins, and mean arterial pressure of 85 mm Hg or greater. Using optimal surgical technique, the probability of successful AVF maturation would have been as high as 84%. A predictive logistic regression model had moderate ability to predict AVF maturation under optimal surgical therapy with an area under the ROC curve of 0.69. CONCLUSION: Surgical technique potentially may be modified to yield a greater probability of successful AVF maturation. Predictive probabilities of successful AVF maturation under optimal surgical technique reinforce the view that functioning AVFs can be achieved in a large proportion of hemodialysis patients, consistent with experience in selected regions of the United States and abroad.

Adult↗
PubMed2005

Neonatal intubation: success of pediatric trainees.

OBJECTIVES: To review the success of pediatric trainees for neonatal intubation over a 10-year interval at a single academic center. STUDY DESIGN: We reviewed a database of all neonatal intubations designed as a quality assurance process at our institution. Respiratory care practitioners recorded the number of attempts at the time of each procedure. Attempts were defined as each time a laryngoscope was placed in the baby's mouth. Success rates were calculated as the number of successful intubations divided by the attempts. RESULTS: From January 1992 through September 2002, 5051 successful intubations with 9190 attempts were performed by all practitioners. Pediatric residents intubated neonates successfully on 1676 occasions requiring 3719 attempts. The median success rates were 33% for pediatric level (PL)1 residents; 40% for PL2 and PL3 residents, and 68% for neonatal fellows ( P < .001). The success rates for residents who had more than 20 total attempts versus those who had fewer than 20 attempts were 49% versus 37% ( P < .001). CONCLUSIONS: Developing proficiency at intubation requires a significant amount of experience. Current pediatric residents at our institution have inadequate opportunity to achieve consistent success.

California↗
PubMed1997

Predictors for successful ablation of right- and left-sided idiopathic ventricular tachycardia.

This study reports on predictors for successful radiofrequency (RF) ablation of idiopathic ventricular tachycardia (VT) in 48 patients--35 with right ventricular (RV) outflow tract and 13 with left ventricular VT. In RV outflow tract idiopathic VT, RF ablation was successful in 29 of 35 patients (83%). The following information allowed differentiation between patients with and without a successful RF ablation: > 1 induced VT morphology (O vs 3); presence of delta wave-like beginning of the QRS (2 vs 3) and > or = 11 of 12 leads showing a "match" between the clinical VT and the pacemap (28 vs 1). Endocardial activation times were not different between both groups (-15 +/- 18 vs -4 +/- 5 ms). In left ventricle idiopathic VT, RF ablation was successful in 12 of 13 patients (92%). In patients who underwent successful ablation, 1 VT morphology was induced and no delta wave-like beginning of the QRS was present; a correlation between clinical VT and the pacemap > or = 11 of 12 leads was found and the endocardial activation time preceded the QRS (range of -5 to -58 ms [mean -30 +/- 14]). Purkinje activity was observed in 5 of 7 patients with an idiopathic VT originating from the inferoposterior region but not from the inferoapical region of the left ventricle. Four patients (14%) with RV outflow tract idiopathic VT had recurrence during a mean follow-up of 2 to 50 months (mean 30 +/- 12). Thus, (1) in RV outflow tract idiopathic VT a good pacemap was more important than an early endocardial activation time; (2) an optimal pacemap as well as an early endocardial activation time were important predictors for successful ablation of the left ventricle idiopathic VT; (3) Purkinje activity was recorded in VTs arising in the inferoposterior region of the left ventricle; and (4) factors for unsuccessful ablation for idiopathic VT were > 1 induced VT morphology, a delta wave-like beginning of the QRS, and a VT/pacemap correlation < 11 of 12 leads. Idiopathic VT can be successfully ablated with both immediate and long-term success.

Adolescent↗
PubMed1995

Stability of in vitro fertilization-embryo transfer success rates from the 1989, 1990, and 1991 Clinic-Specific Outcome Assessments.

OBJECTIVE: To determine if the differences in IVF-ET success rates among clinics are due to chance alone. DESIGN: Retrospective analysis of data reported by individual clinics. SETTING: One hundred seventy-five clinics in 1989, 192 clinics in 1990, and 208 clinics in 1991 that reported IVF-ET success rates to the Society for Assisted Reproductive Technology and the American Society for Reproductive Medicine (formerly The American Fertility Society). PATIENTS: Women < 40 years of age with no male factor. INTERVENTION: In vitro fertilization-ET. MAIN OUTCOME MEASURE: Delivery rate per retrieval and delivery rate per transfer. RESULTS: The hypothesis that the differences among IVF-ET success rates for clinics is due to chance alone can be rejected. Seven clinics were found to have pregnancy rates significantly higher than average and six clinics were found to have pregnancy rates significantly lower than average. Significant correlations were found between different years in the success rates for individual clinics but not for success as a function of the number of patients treated. CONCLUSIONS: Success rates for a few clinics are significantly different from the average success rate, but success rates must be used with caution in selecting a clinic.

Adult↗