-
[show abstract]
[hide abstract]
ABSTRACT: Context: Pain is a commonly experienced and distressing symptom in women with breast cancer (BCA), and recent evidence suggests that immune activation may be associated with pain and other co-occurring symptoms. However, no studies to date have explored the relationships among perceived pain and biomarkers of inflammation in women with early-stage BCA during the initial course of treatment. Objectives: The purpose of this research study was to examine the relationships among pro- and anti-inflammatory biomarkers and the presence of pain and other symptoms (anxiety, depression, fatigue, and sleep disorder) prior to induction of chemotherapy. Method: This was a secondary analysis of data that measured perceived symptoms, including the presence of pain and pain interference, and plasma levels of pro- and anti-inflammatory cytokines and C-reactive protein (CRP) in women with early-stage BCA (N = 32) at 1 month postsurgery but prior to induction of chemotherapy. Results: Women experiencing pain had significantly higher levels of CRP (p < .01), interleukin (IL) 13 (p < .02), and IL-7 (p < .02) and more pain interference (p < .01), depression (p < .01), and sleep disturbance (p < .01) compared to women reporting no pain. Conclusion: The presence of pain during the initial course of treatment in women with early-stage BCA was associated with significantly higher levels of CRP, IL-7, and IL-13, suggesting a potential role of immune activation in perceived pain. Further research to examine the precise effects of these biological factors in modulating pain is needed. Perceived pain was also associated with multiple co-occurring symptoms, and this finding has important implications for symptom management.
Biological Research for Nursing 11/2011; · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The theory of heart failure (HF) self-care proposes that confidence mediates relationships between social support and self-care behaviors.
This study aimed to examine the effects of supportive relationships on self-care behaviors and the mediating effects of self-care confidence in HF outpatients.
Structural equation modeling (SAS version 9.1, SAS Institute Inc, Cary, North Carolina) was used to examine the influence of supportive relationships and self-care confidence on self-care management and maintenance in a cross-section of patients with HF (n = 97; age = 56 years; 57% men; 45% African American; 55% married). Models included 3 variables characterizing supportive relationships: marital status (1 = currently married, 0 = not currently married), social network size (number of persons available to provide support), and perceived social support (Medical Outcomes Study Social Support Scale). To account for the effects of severity of illness, 2 measures characterizing severity of HF were included: left ventricular ejection fraction and New York Heart Association functional classification of HF. The Self-Care of Heart Failure Index (version 4) was used to measure self-care confidence, management, and maintenance. A consensus of fit indices estimated overall model fit.
Initial models fit the data; however, to improve fit and identify the most parsimonious models, 3 nonsignificant paths were removed, and modified models, including only social support and social network size, were proposed and tested. Modified models fit the data well and accounted for 15% in the variance in self-care maintenance (χ(2) P = .29) and 18% of the variance in self-care management (χ(2) P = .631). The indirect effect of social support (β = 0.37; P = .0004) through self-care confidence (β = 0.35; P = .0002) on self-care management, in the absence of a significant direct effect, supports the hypothesis that self-care confidence mediates the relationship between social support and self-care management. Social network size had a negative effect on self-care confidence (β = -0.22; P = .029), but this effect was mediated by self-care confidence (β = 0.33; P = .0002), which reduced the total negative effects. Self-care confidence was the best predictor of self-care management. In the self-care maintenance model, direct (β = 0.27; P = .003) and indirect effects of social support (β = 0.37; P = .0002) on self-care maintenance through self-care confidence (β = 0.22; P = .001) attenuated negative effects of social network size (β = -0.22; P = .0145). Social support was the best predictor of self-care maintenance.
Findings support the positive influence of social support on self-care behaviors. Self-care confidence mediated the relationship between social support and self-care behaviors and had direct influence on these behaviors as well. This suggests that self-care confidence and self-care behaviors can be enhanced by improving the quality of social support.
The Journal of cardiovascular nursing 11/2011; 27(5):384-93. · 1.43 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This report extends the findings of a prior study comparing the level of plasma cytokines in women with breast cancer to those of women with a benign breast biopsy with the addition of a normal comparison group. The results of this three-group comparison are presented as background for discussing several methodologic challenges for biobehavioral research in inflammatory-based conditions.
This study used a descriptive, cross-sectional design to compare the levels of plasma cytokines in women with breast cancer, women with a benign breast biopsy, and a normal comparison group. The levels of 17 cytokines were measured using multiplex bead array assays (Bio-Plex®). Data analysis included a variety of descriptive and graphical techniques to illustrate between-group differences in cytokine profiles.
The levels of plasma cytokines in the sample of 35 women who had recently been diagnosed with breast cancer, 24 women with a suspicious breast mass, who subsequently were found to have a benign breast biopsy, and 33 women in a normal comparison group present a background for discussing the implications of extreme between-group differences for biobehavioral nursing research. Both the levels of individual cytokines and their patterns were distinctly different in the three groups.
The exemplar presented from the three-group comparison has implications for planning biobehavioral nursing research in patients with conditions characterized by inflammation.
Biological Research for Nursing 01/2011; 13(1):25-31. · 1.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Altered tryptophan metabolism and indoleamine 2,3-dioxygenase activity are linked to cancer development and progression. In addition, these biological factors have been associated with the development and severity of neuropsychiatric syndromes, including major depressive disorder. However, this biological mechanism associated with both poor disease outcomes and adverse neuropsychiatric symptoms has received little attention in women with breast cancer. Therefore, a pilot study was undertaken to compare levels of tryptophan and other proteins involved in tryptophan degradation in women with breast cancer to women without cancer, and secondarily, to examine levels in women with breast caner over the course of chemotherapy.
Blood samples were collected from women with a recent diagnosis of breast cancer (n = 33) before their first cycle of chemotherapy and after their last cycle of chemotherapy. The comparison group (n = 24) provided a blood sample prior to breast biopsy. Plasma concentrations of tryptophan, kynurenine, and tyrosine were determined. The kynurenine to tryptophan ratio (KYN/TRP) was used to estimate indoleamine 2,3-dioxygenase activity. On average, the women with breast cancer had lower levels of tryptophan, elevated levels of kynurenine and tyrosine and an increased KYN/TRP ratio compared to women without breast cancer. There was a statistically significant difference between the two groups in the KYN/TRP ratio (p = 0.036), which remained elevated in women with breast cancer throughout the treatment trajectory.
The findings of this pilot study suggest that increased tryptophan degradation may occur in women with early-stage breast cancer. Given the multifactorial consequences of increased tryptophan degradation in cancer outcomes and neuropsychiatric symptom manifestation, this biological mechanism deserves broader attention in women with breast cancer.
BMC Research Notes 01/2011; 4:156.
-
[show abstract]
[hide abstract]
ABSTRACT: We sought to determine allele frequencies of 3 LAMC1 single nucleotide polymorphisms (SNPs) in Caucasian and African American (AA) women with stage>II pelvic organ prolapse (POP) (cases) and in ethnicity-matched controls with stage<II POP. We also sought to determine if LAMC1 is associated with POP within ethnic groups.
Allelic discrimination was performed for LAMC1 SNPs rs10911193 (C/T), rs20563 (A/G), and rs20558 (T/C). SNP and haplotype-specific tests were used to examine associations among POP, ethnicity, and LAMC1.
In all, 411 women were enrolled. Significant differences in allele and haplotype frequencies existed among AAs and Caucasians: rs10911193 "T" (P=.0014); rs20563 "G" (P<.0001); rs20558 "C" (P<.0001); rs20563, rs20558 "GC" (P<.0001); and rs20563, rs20558 "AT" (P<.0001). No significant associations between POP and LAMC1 SNPs or haplotypes were found within ethnicities.
While significant differences were identified between AA and Caucasian women, no associations were found between any LAMC1 gene variant and advanced POP.
American journal of obstetrics and gynecology 03/2010; 202(5):505.e1-5. · 3.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This exploratory study builds on existing research on the physiological stress response to human-animal interactions in a non-clinical sample of adult dog-owners interacting with their own or an unfamiliar therapy dog under similar conditions. Participants were therapy-dog owners (TDO group; n = 5) interacting with their own dogs and dog owners interacting with an unfamiliar therapy dog (AAA group; n = 5). Following a 30minute baseline period, participants completed a stress task followed by a 30-minute dog interaction and then watched a neutral video for 60 minutes. The outcome variable of interest was the bio-behavioral stress response, measured by systolic and diastolic blood pressure (SBP, DBP), heart rate (HR), salivary cortisol, salivary alpha-amylase, and self-report. Trait anxiety and attitudes toward pets were assessed as moderating variables. Results revealed consistent physiological patterns, showing modest increases with the stressor and decreases from baseline following the intervention, for salivary cortisol, SBP, DBP, HR, and self reported anxiety and stress for both groups. In general, although the TDO group tended to perceive less stress and anxiety during the intervention than the AAA group, greater reductions in physiological measures were observed in the AAA group. Positive attitudes toward pets in the total sample of dog owners were associated with decreased levels of self-reported stress (p < 0.05), salivary cortisol, and SBP, while higher levels of trait anxiety were associated with higher levels of salivary cortisol (p < 0.05). In addition, higher levels of trait anxiety were associated with lower levels of autonomic nervous system indicators of stress (HR; SBP, p < 0.05; DBP, p < 0.05). Results support a buffering effect on the stress response associated with owners interacting with their dogs that may extend to interactions with unfamiliar therapy dogs in AAA, and supports the need for replication studies with larger sample sizes.
Anthrozoos A Multidisciplinary Journal of The Interactions of People & Animals 02/2010; 23(1):79-91. · 0.86 Impact Factor
-
Jasmohan S Bajaj, Christine M Schubert,
Douglas M Heuman,
James B Wade,
Douglas P Gibson,
Allyne Topaz,
Kia Saeian,
Muhammad Hafeezullah,
Debulon E Bell,
Richard K Sterling,
R Todd Stravitz,
Velimir Luketic,
Melanie B White,
Arun J Sanyal
[show abstract]
[hide abstract]
ABSTRACT: In patients with cirrhosis, hepatic encephalopathy (HE) has acute but reversible as well as chronic components. We investigated the extent of residual cognitive impairment following clinical resolution of overt HE (OHE).
Cognitive function of cirrhotic patients was evaluated using psychometric tests (digit symbol, block design, and number connection [NCT-A and B]) and the inhibitory control test (ICT). Improvement (reduction) in ICT lures and first minus second halves (DeltaL(1-2)) were used to determine learning of response inhibition. Two cross-sectional studies (A and B) compared data from stable cirrhotic patients with or without prior OHE. We then prospectively assessed cognitive performance, before and after the first episode of OHE.
In study A (226 cirrhotic patients), 54 had experienced OHE, 120 had minimal HE, and 52 with no minimal HE. Despite normal mental status on lactulose after OHE, cirrhotic patients were cognitively impaired, based on results from all tests. Learning of response inhibition (DeltaL(1-2) > or =1) was evident in patients with minimal HE and no minimal HE but was lost after OHE. In study B (50 additional patients who developed > or =1 documented OHE episode during follow-up), the number of OHE hospitalizations correlated with severity of residual impairment, indicated by ICT lures (r = 0.5, P = .0001), digit symbol test (r = -0.39, P = .002), and number connection test-B (r = 0.33, P = .04). In the prospective study (59 cirrhotic patients without OHE), 15 developed OHE; ICT lure response worsened significantly after OHE (12 before vs 18 after, P = .0003), and learning of response inhibition was lost. The 44 patients who did not experience OHE did not have deteriorations in cognitive function in serial testing.
In cirrhosis, episodes of OHE are associated with persistent and cumulative deficits in working memory, response inhibition, and learning.
Gastroenterology 02/2010; 138(7):2332-40. · 11.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To estimate sensitivity, specificity, and positive and negative predictive values of components of the metabolic syndrome (MetS) during childhood for MetS and type 2 diabetes (T2D) in adulthood.
Data from 3 major studies-the Fels Longitudinal Study, the Muscatine Study, and the Princeton Follow-up Study-were combined to examine how thresholds of metabolic components during childhood determine adult MetS and T2D. Available metabolic components examined in the 1789 subjects included high-density lipoprotein, triglyceride levels, glucose, and percentiles for body mass index, waist circumference, triglycerides, and systolic and diastolic blood pressures. Sensitivity, specificity, and positive and negative predictive values for a refined set of component threshold values were examined individually and in combination.
Sensitivity and positive predictive values remained low for adult MetS and T2D for individual components. However, specificity and negative predictive values were fairly high for MetS and exceptionally so for T2D. In combination, having 1 or more of the components showed the highest sensitivity over any individual component and high negative predictive value. Overall, specificity and negative predictive values remained high whether considering individual or combined components for T2D.
Sensitivity and positive predictive values on the basis of childhood measures remained relatively low, but specificity and negative predictive values were consistently higher, especially for T2D. This indicates that these components, when examined during childhood, may provide a useful screening approach to identifying children not at risk so that further attention can be focused on those who may be in need of future intervention.
The Journal of pediatrics 10/2009; 155(3):S6.e1-7. · 4.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To determine whether waist circumference (WC) and family history of disease increase the predictive utility of body mass index (BMI) for adult metabolic syndrome (MetS).
A subsample of 161 men and women from the Fels Longitudinal Study with childhood and adulthood measures were analyzed. Using logistic regression, childhood BMI categories (50th, 75th, and 85th percentiles), WC categories (75th and 90th percentiles), and family history of type 2 diabetes mellitus or cardiovascular disease were modeled separately and in combinations to predict adult MetS. Predicted probabilities and c-statistics were compared across models.
The addition of family history to BMI improved the predicted probability of adult MetS from 29% to 52% (Deltac-statistic = 0.13). The combination of WC and BMI was more predictive than BMI alone but did not outperform the combination of family history and BMI. In 3 of the 4 models with a combination of family history, WC, and BMI, the predicted probability of adult MetS did not exceed that from the combination of family history and BMI.
Family history of type 2 diabetes or cardiovascular disease is a useful addition to BMI in childhood to predict the future risk of adult MetS.
The Journal of pediatrics 10/2009; 155(3):S6.e9-13. · 4.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To ascertain the influence of such a prolonged juvenile state on delaying the onset of the metabolic syndrome, cardiovascular disease, and type 2 diabetes mellitus later in life.
We define prolongation of a juvenile state as a retarded tempo of growth, determined by the timing of peak height velocity in each subject and relate the retarded tempo of growth to metabolic syndrome, cardiovascular disease, and type 2 diabetes mellitus later in life by use of serial data of 237 study participants (119 men and 118 women) enrolled in the Fels Longitudinal study.
Children who matured early tended to have greater body mass index, waist circumference, and percent of body fat and were more likely to have adverse cardiovascular risk profiles than children who matured late. The differences in these risk factors between early and late maturers were significant for percent body fat, fasting plasma triglycerides, and fasting plasma insulin.
The analyses disclosed a clear separation between early and late maturers in the appearance of these risk factors in young adulthood.
The Journal of pediatrics 10/2009; 155(3):S7.e1-6. · 4.02 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Despite the success of catheter ablation of cavotricuspid isthmus-dependent atrial flutter (AFL), important postablation outcomes are ill-defined. The purpose of our study was to analyze long-term outcomes after catheter ablation of cavotricuspid isthmus-dependent AFL.
A meta-analysis was performed of articles reporting clinical outcomes after catheter ablation of AFL published between January 1988 and July 2008. The analysis included 158 studies comprising 10 719 patients (79% men, 59.8+/-0.5 years old, 46% left atrial enlargement, 46% heart disease, 42% with history of atrial fibrillation, 14.3+/-0.4 months of follow-up). The overall acute success rate adjusted for reporting bias was 91.1% (95% CI, 89.5 to 92.4), 92.7% (95% CI, 90.0 to 94.8) for 8- to 10-mm tip/or irrigated radiofrequency catheters, and 87.9% (95% CI, 84.2 to 90.9) for 4- to 6-mm tip catheters (P>0.05). Atrial flutter recurrence rates were significantly reduced by use of 8- to 10-mm tip or irrigated radiofrequency catheters (6.7% versus 13.8%, P<0.05) and by use of bidirectional cavotricuspid isthmus block as a procedural end point (9.3% versus 23.6%, P<0.05). The AFL recurrence rate did not increase over time. The overall occurrence rate of atrial fibrillation after AFL ablation was 33.6% (95% CI, 29.7 to 37.3) but was 52.7% (95% CI, 47.8 to 57.6) in patients with a history of atrial fibrillation before ablation and 23.1% (95% CI, 17.5 to 29.9) in those without atrial fibrillation before ablation (P<0.05). The incidence of atrial fibrillation increased over time in both groups; however, 5 years after ablation, the incidence of atrial fibrillation was similar in those with and without atrial fibrillation before ablation. The acute complication rate was 2.6% (95% CI, 2 to 3). The mortality rate during follow-up was 3.3% (95% CI, 2.4 to 4.5). Antiarrhythmic drug use after ablation was 31.6% (95% CI, 25.6 to 37.8). The long-term use of coumadin was 65.9%, (95% CI, 43.8 to 82.8). Quality of life data were very limited.
AFL ablation is safe and effective. Ablation technology and procedural end points have greater influences on AFL recurrences than on acute ablation success rates. Atrial fibrillation is common after AFL ablation. Almost one third of patients take antiarrhythmic drugs after AFL ablation. Atrial fibrillation before AFL ablation may indicate a more advanced state of electric disease.
Circulation Arrhythmia and Electrophysiology 08/2009; 2(4):393-401. · 6.46 Impact Factor
-
Jasmohan S Bajaj,
Kia Saeian, Christine M Schubert,
Muhammad Hafeezullah,
Jose Franco,
Rajiv R Varma,
Douglas P Gibson,
Raymond G Hoffmann,
R Todd Stravitz,
Douglas M Heuman,
Richard K Sterling,
Mitchell Shiffman,
Allyne Topaz,
Sherry Boyett,
Debulon Bell,
Arun J Sanyal
[show abstract]
[hide abstract]
ABSTRACT: Patients with minimal hepatic encephalopathy (MHE) have impaired driving skills, but association of MHE with motor vehicle crashes is unclear. Standard psychometric tests (SPT) or inhibitory control test (ICT) can be used to diagnose MHE. The aim was to determine the association of MHE with crashes and traffic violations over the preceding year and on 1-year follow-up. Patients with cirrhosis were diagnosed with MHE by ICT (MHEICT) and SPT (MHESPT). Self and department-of-transportation (DOT)-reports were used to determine crashes and violations over the preceding year. Agreement between self and DOT-reports was analyzed. Patients then underwent 1-year follow-up for crash/violation occurrence. Crashes in those with/without MHEICT and MHESPT were compared. 167 patients with cirrhosis had DOT-reports, of which 120 also had self-reports. A significantly higher proportion of MHEICT patients with cirrhosis experienced crashes in the preceding year compared to those without MHE by self-report (17% vs 0.0%, P = 0.0004) and DOT-reports (17% vs 3%, P = 0.004, relative risk: 5.77). SPT did not differentiate between those with/without crashes. A significantly higher proportion of patients with crashes had MHEICT compared to MHESPT, both self-reported (100% vs 50%, P = 0.03) and DOT-reported (89% vs 44%, P = 0.01). There was excellent agreement between self and DOT-reports for crashes and violations (Kappa 0.90 and 0.80). 109 patients were followed prospectively. MHEICT patients had a significantly higher future crashes/violations compared to those without (22% vs 7%, P = 0.03) but MHESPT did not. MHEICT (Odds ratio: 4.51) and prior year crash/violation (Odds ratio: 2.96) were significantly associated with future crash/violation occurrence. CONCLUSION: Patients with cirrhosis and MHEICT have a significantly higher crash rate over the preceding year and on prospective follow-up compared to patients without MHE. ICT, but not SPT performance is significantly associated with prior and future crashes and violations. There was an excellent agreement between self- and DOT-reports.
Hepatology 07/2009; 50(4):1175-83. · 11.66 Impact Factor
-
Jasmohan S Bajaj,
Muhammad Hafeezullah,
Yelena Zadvornova,
Eric Martin, Christine M Schubert,
Douglas P Gibson,
Raymond G Hoffmann,
Arun J Sanyal,
Douglas M Heuman,
Thomas A Hammeke,
Kia Saeian
[show abstract]
[hide abstract]
ABSTRACT: Hepatic encephalopathy, both overt (OHE) and minimal (MHE), is associated with poor quality of life and fatigue. The aim of this study was to define the effect of fatigue on driving skills in MHE and OHE patients.
Cirrhotics and age/education-matched controls were administered a psychometric battery of tests to diagnose MHE. Cirrhotics with recent OHE on lactulose were also included. All subjects underwent a driving simulation; to assess fatigue, the second half performance was compared with the first half of the simulation. The outcomes were collisions, speeding, road excursions, and center crossings. Actual driving-associated fatigue was assessed by the American Medical Association (AMA) driver survey.
A total of 100 cirrhotics (51 MHE, 27 no MHE, and 22 OHE) and 67 controls were included. A significantly higher proportion of OHE and MHE patients admitted to fatigue after actual driving on the AMA survey compared with no MHE patients (P=0.02). All patients who admitted to fatigue and none who denied fatigue on the AMA survey had simulator collisions. Psychometric and simulator performance in treated OHE patients was similarly impaired to MHE patients despite therapy. Within groups, a significant increase in collisions, speeding, and center crossings in the second half (P=0.01) was seen only in MHE patients.
Psychometric and simulator performance in patients with recent OHE on treatment is similarly impaired as that of untreated MHE patients. Simulator performance in MHE worsens over time with fatigue. OHE and MHE patients had a higher rate of actual driving-associated fatigue on the AMA survey, which was significantly predictive of simulator collisions.
The American Journal of Gastroenterology 05/2009; 104(4):898-905. · 7.28 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The objectives of the present study were (1) to assess receptive language scores in children after cochlear implantation and compare them with scores in normal hearing children and children with hearing loss that use hearing aids and (2) to determine how demographic factors, such as age of implantation, impact language outcomes.
Case series.
Receptive language scores in children with profound prelingual hearing loss who received cochlear implants between 1996 and 2004 were analyzed.
Standardized language assessments were available for 36 children. The average age at implantation was 33 months. The mean language scores for implanted children were within 1 standard deviation of scores of normal hearing individuals. Children with cochlear implants had significantly higher subtest scores (P < 0.05) than children with hearing aids. Children with additional disabilities had significantly (P < 0.05) poorer language performance.
Pediatric cochlear implant recipients acquire receptive language skills that approach those of their hearing peers and exceed those of children with hearing aids.
Otolaryngology Head and Neck Surgery 02/2009; 140(1):114-9. · 1.72 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The relative lesion sizes created by large electrode cryoablation catheter and irrigated radiofrequency (RF) ablation are not known. The purpose of this study was to directly compare lesion sizes created by cryoablation and irrigated RF under controlled conditions.
Ablation lesions were created in freshly harvested porcine left ventricular myocardium in a blood-filled tissue bath using an 8-mm-tip cryoablation catheter and a 3.5-mm-tip open-irrigated RF ablation catheter. Lesions were created under all permutations of the following conditions: electrode orientation vertical (perpendicular) or horizontal (parallel) to the tissue, electrode contact pressure at 6 or 20 g, and blood flow at 0.2 or 0.4 m/s over the electrode-tissue interface. The largest lesion volumes created with cryoablation were 961 +/- 103 mm(3), compared with the largest lesions volumes created with RF of 680 +/- 48 mm(3) (P < 0.001). The 3-way interactions among electrode orientation, contact pressure, and superfusate blood velocity accounted for the variation in lesion volumes for both catheters (both r(2)= 0.97, both P < 0.0001). The greater contact pressure increased lesion size for both cryoablation and RF. For cryoablation, lesion sizes were increased by the horizontal orientation and by the lower blood flow velocity. For open-irrigated RF, lesion sizes were significantly reduced by the horizontal orientation, however.
Depending on conditions of electrode orientation, contact pressure, and blood velocity, either 8-mm-tip cryoablation or open-irrigated RF may produce the larger lesion volumes. Open-irrigated RF lesion sizes are reduced in the horizontal catheter orientation.
Journal of Cardiovascular Electrophysiology 06/2008; 19(5):528-34. · 3.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: There are no methods in clinical use to assess tissue cooling during catheter cryoablation. Cryoablation electrode temperature may be a poor predictor of lesion size. The purpose of this study was to determine whether the time necessary for the cryoablation electrode to cool to target temperature or to rewarm after cryoablation can predict lesion size.
Cryoablation was performed on live porcine left ventricle in a saline bath (37 degrees C) using 8-mm-tip catheter. Cryoablation was given for 300 seconds under all permutations of the following conditions: electrode orientation vertical or horizontal, contact pressure 6 or 20 g, superfusate flow over electrode-tissue interface at 0.2 or 0.4 m/s (N = 10 each condition set, total 80 experiments). The time intervals necessary to cool the electrode to the target temperature of -75 degrees C and to rewarm to + 30 degrees C after termination of cryoablation were recorded. Lesion volume was predicted best by the time necessary to rewarm the electrode to +30 degrees C (r2 = 0.65, P < 0.0001), followed by electrode temperature (r2 = 0.28, P < 0.0001) and time to cool the electrode to -75 degrees C (r2 = 0.24, P < 0.0001). Time to +30 degrees C and time to -75 degrees C were associated with superfusate flow rate, contact pressure, and electrode orientation (r2 = 0.80 and 0.61, respectively, both P < 0.0001). Superfusate flow rate, contact pressure, and orientation were also highly predictive of lesion volume (r2 = 0.93, P < 0.0001).
Time to cryoablation electrode rewarming is a better predictor of cryoablation lesion size than is electrode temperature. Time to cryoablation electrode rewarming reflects important determinants of cryoablation lesion formation--convective warming, contact pressure, and electrode orientation--that are not ascertainable during clinical ablation procedures.
Journal of Cardiovascular Electrophysiology 08/2007; 18(8):845-8. · 3.06 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Factors which influence lesion size from catheter-based cryoablation have not been well described. This study describes factors which influence lesion size during catheter cryoablation.
Cryoablation was delivered to porcine left ventricular myocardium in a saline bath using 4- or 8-mm electrode catheters. Ablation was delivered with the electrodes either vertical or horizontal to the tissue and both with and without superfusate flow over the electrode. The effect of electrode contact pressure was tested. Lesion dimensions were measured. All experiments were duplicated to measure tissue temperatures at 1-, 2-, 3-, and 5-mm deep to the ablation electrode. The 8-mm electrode produced lower tissue temperatures and larger lesion volumes when compared with the 4-mm electrode (all P < 0.05). Superfusate flow slowed the rate of tissue cooling, markedly warmed tissue temperatures, and reduced lesion volume when compared with no flow conditions. By linear regression modeling, lesion sizes and tissue temperatures were related to the presence of superfusate flow, electrode orientation, contact pressure and electrode size, or catheter refrigerant flow rate (r2 for models = 0.90-0.96, all P < 0.001). Electrode temperature predicted lesion size or tissue temperatures only when analyzed independent of electrode size or refrigerant flow rate.
Lesion sizes and tissue temperatures during catheter cryoablation are related to convective warming, electrode orientation, electrode contact pressure, and any of the following: electrode size, catheter refrigerant flow rate or electrode temperature. However, electrode temperature may be a poor predictor of lesion size and tissue temperature for a given catheter size.
Pacing and Clinical Electrophysiology 06/2007; 30(5):644-54. · 1.35 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Gaps of sufficient cross-sectional dimensions within linear radiofrequency (RF) lesions may allow conduction through the lesion. The purpose of this study was to examine the effects of different gap geometries on conduction through discontinuous RF lesions.
Radiofrequency lesions were created in isolated, perfused rabbit right ventricular (RV) free wall preparations to produce gaps with 3 different lesion geometries: straight, bifurcated, and angled (n=10 each group). Angled preparations contained 2 right angles within the conduction path. Optical mapping was used to assess bidirectional conduction through the myocardium before and after gap formation during pacing at 1000-, 400-, and 200-ms cycle lengths. Histological analysis was performed on each preparation after optical mapping. After lesion formation, 9 of 10 straight gap preparations and 1 of 10 angled gap preparations demonstrated bidirectional conduction (P<0.001) at all cycle lengths. Nine of 10 bifurcated gap preparations demonstrated bidirectional conduction and 1 demonstrated unidirectional conduction at all cycle lengths. Two bifurcated gap preparations showed rate-dependent unidirectional 2:1 conduction. All unidirectional and rate-dependent block occurred during impulse propagation in the direction of diverging arms of the bifurcation. The occurrence of bidirectional conduction in the gaps was associated with the gap geometry (P<0.0001). Histological analysis confirmed the continuity of viable myocardium transmurally throughout the length of the gap in each preparation. The sites of conduction block were demonstrated to be just after the first angle in the conduction path for angled gaps and at the branch point of a bifurcated gap. The predominant myofiber orientation was changed relative to the conduction path at angulations of the gaps. Flecainide (0.1 micromol/L) produced bidirectional conduction block in straight and bifurcated gap preparations with bidirectional conduction at baseline.
Conduction through discontinuities in RF lesions is associated with gap geometry. Complex gap geometry may allow for unidirectional and/or rate-dependent block. Gaps within RF lesions are susceptible to pharmacological blockade.
Circulation 05/2006; 113(14):1723-9. · 14.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Our aim was to examine the degree to which changes in BMI percentile reflect changes in body fat and lean body mass during childhood and how age and gender affect these relationships.
This analysis used serial data on 494 white boys and girls who were aged 8 to 18 years and participating in the Fels Longitudinal Study (total 2319 observations). Total body fat (TBF), total body fat-free mass (FFM), and percentage of body fat (%BF) were determined by hydrodensitometry, and then BMI was partitioned into its fat and fat-free components: fat mass index (FMI) and FFM index (FFMI). We calculated predicted changes (Delta) in FMI, FFMI, and %BF for each 10-unit increase in BMI percentile using mixed-effects models.
FFMI had a linear relationship with BMI percentile, whereas FMI and %BF tended to increase dramatically only at higher BMI percentiles. Gender and age had significant effects on the relationship between BMI percentile and FFMI, FMI, and %BF. Predicted Delta%BF for boys 13 to 18 years of age was negative, suggesting loss of relative fatness for each 10-unit increase in BMI percentile.
In this longitudinal study of white children, FFMI consistently increased with BMI percentile, whereas FMI and %BF had more complicated relationships with BMI percentile depending on gender, age, and whether BMI percentile was high or low. Our results suggest that BMI percentile changes may not accurately reflect changes in adiposity in children over time, particularly among male adolescents and children of lower BMI.
PEDIATRICS 04/2006; 117(3):e487-95. · 4.47 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This study investigates the extent to which discordant Tanner stages for sexual maturity indicators are associated with weight and body mass index (BMI) and their variation during adolescence. Discordant children with large differences in weight and BMI may require additional monitoring of their growth during adolescence.
Weight, BMI and Tanner stages, pubic hair in each gender, breast development in girls and genital development in boys, from 2103 boys and 2104 girls aged 8-18 years (average age 13.34 years) from the National Health and Nutrition Examination Survey III (NHANES III, 1988-1994) were analyzed. These cross-sectional data were grouped as concordant: assessed stages for paired indicators were equivalent, or as discordant: assessed stage for one paired indicator was greater or less than the other by one or more stages. Weight and BMI were compared separately by gender and race between concordant and discordant groups using analysis of covariance adjusted for age.
Approximately 65-69% of all children were concordant, genital stage equaled pubic hair stage for boys and breast stage equaled pubic hair stage for girls. For all three racial groups, boys whose genital stage was more advanced than their pubic hair stage had significantly smaller weight and BMI (p<.05) than either concordant boys or boys whose pubic hair stage was more advanced than their genital stage. For all three racial groups, girls whose breast stage was more advanced than their pubic hair stage had significantly greater weight and BMI than girls whose pubic hair stage was more advanced than breast stage. Non-Hispanic black and Mexican-American girls whose breast stage was more advanced than their pubic hair stage had significantly greater weight and BMI that the respective concordant girls.
Substantial and significant differences occur in weight and BMI among discordant and concordant children, and these differences are larger than between early and late maturing children.
Journal of Adolescent Health 12/2005; 37(5):356-62. · 3.33 Impact Factor
