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Biomedical subjects

Joshua Cooper

Publications and source records attributed to Joshua Cooper.

8 recordsLinked to original sources

Characteristics of patients undergoing atrial fibrillation ablation: trends over a seven-year period 1999-2005.

BACKGROUND: Catheter ablation procedures for treating atrial fibrillation (AF) have dramatically increased since triggers of AF were first described in 1998. OBJECTIVE: We explored changes in patient characteristics in patients referred for catheter ablation of AF over a seven-year period from 1999 through 2005. METHODS: Patient characteristics were examined for all patients undergoing AF ablation from 1999 through 2005 at the University of Pennsylvania Health System (UPHS). The gender of patients undergoing ablation was also compared with outpatients seen at UPHS with a primary diagnosis of AF. RESULTS: From 1999 to 2005 the number of patients undergoing ablation has increased steadily, from 29 patients in 1999 to 265 patients in 2005 (P < 0.01). Patients have become older (47 to 56 years; P < 0.01), with more persistent or permanent AF (17% to 45%; P < 0.01), larger left atrial size (4.0 to 4.4 cm; P < 0.01), and fewer antiarrhythmic drugs used prior to ablation (3.9 to 2.0 drugs; P < 0.01). Patients undergoing ablation have been predominantly male, with a significantly higher male prevalence than patients seen in the UPHS outpatient primary care clinic with AF (77% vs 59% male; P < 0.001). CONCLUSIONS: Patients undergoing AF ablation from 1999 to 2005 are older, with larger left atrial size, more persistent/permanent AF, and fewer prior antiarrhythmic agents used. Compared with the gender-specific rates of AF in the population, the majority of patients referred for ablation are men, suggesting a referral bias against this invasive procedure for women. These findings are important for interpreting the outcome of ablation in the current era, and for designing prospective randomized trials.

Aged↗

Ventricular tachycardia/ventricular fibrillation ablation in the setting of ischemic heart disease.

Recurrent ventricular tachycardia (VT) in the setting of coronary artery disease is frequently a life-threatening electrophysiologic emergency. Even in patients with an implantable defibrillator, recurrent VT is frequently accompanied by repeated and disabling shock therapy. Catheter ablative therapy offers the ability to provide immediate control of recurrent VT. Long-term elimination of VT should be anticipated in most patients. This article reviews the strategies, tools, techniques, and expected outcome for catheter ablation of stable and unstable ventricular arrhythmias in the setting ischemic heart disease.

Catheter Ablation↗

Evaluation of physiological responses during recovery following three resistance exercise programs.

The present study was conducted to examine (a) whether there is an association between maximal oxygen uptake (Vo(2)max) and reduction in postexercise heart rate (HR) and blood lactate concentrations ([La]) following resistance exercise and (b) how intensity and Volume of resistance exercise affect postexercise Vo(2). Eleven regularly weight-trained males (20.8 +/- 1.3 years; 96.2 +/- 14.4 kg, 182.4 +/- 7.3 cm) underwent 4 sets of squat exercise on 3 separate occasions that differed in both exercise intensity and volume. During each testing session, subjects performed either 15 repetitions.set(-1) at 60% of 1 repetition maximum (1RM) (L), 10 repetitions.set(-1) at 75% of 1RM (M), or 4 repetitions.set(-1) at 90% of 1RM (H). During each exercise, Vo(2) and HR were measured before (PRE), immediately post (IP), and at 10 (10P), 20 (20P) 30 (30P), and 40 (40P) minutes postexercise. The [La] was measured at PRE, IP, 20P, and 40P. Decrease in HR (DeltaHR) was determined by subtracting HR at 10P from that at IP, whereas decrease in [La] (Delta[La]) was computed by subtracting [La] at 20P from that at IP. A significant correlation (p < 0.05) was found between Vo(2)max and DeltaHR in all exercise conditions. A significant correlation (p < 0.05) was also found between Vo(2)max and Delta[La] in L and M but not in H. The Vo(2) was higher (p < 0.05) during M than H at IP and 10P, while no difference was seen between L and M and between L and H. These results indicate that those with greater aerobic capacity tend to have a greater reduction in HR and [La] during recovery from resistance exercise. In addition, an exercise routine performed at low to moderate intensity coupled with a moderate to high exercise volume is most effective in maximizing caloric expenditure following resistance exercise.

Adaptation, Physiological↗

The effect of a competitive collegiate football season on power performance and muscle oxygen recovery kinetics.

Ten intercollegiate football players were tested within 3 days prior to (T1) and the day following the end (T2) of football preseason training camp and during weeks 7 (T3) and 11 (T4) of the competitive season. During each testing session, subjects performed a 30-second Wingate anaerobic power test. Near-infrared continuous wave spectroscopy was used to measure muscle deoxygenation during exercise. No changes in any power performance measures were seen during the competitive football season. A significant (p < 0.05) decrease in the extent of deoxygenation during exercise was observed between T2 (72.6 +/- 19.4%) and T4 (50.2 +/- 14.2%). A 30 and 29% difference (p < 0.05) in the onset of reoxygenation was observed between T1 and T3 and T4, respectively. A 51% decrease (p < 0.05) in halftime recovery was observed between T2 and T3. Results indicate that the extent of muscle deoxygenation is reduced during high-intensity exercise and that muscle oxygen recovery kinetics improves over the duration of a competitive season of football.

Adult↗

Optimizing RF output for cooled RF ablation.

Cooled RF ablation catheters increase lesion size and facilitate ablation compared to standard RF ablation catheters. Cooling the ablation electrode increases the disparity between tissue temperature and electrode temperature, making use of temperature for guiding power application during ablation of less certain value. Appropriate energy titration is important, however, to produce large lesions, while avoiding overheating of tissue with steam formation leading to "pops." In addition to power, the rate of irrigant flow can be controlled. Electrode-tissue contact and orientation and the cooling effect of blood flow around the electrode and within the tissue are not as easily adjusted and also influence tissue heating. In addition to electrode temperature, a decrease in impedance, bubble formation detected by intracardiac ultrasound, and evidence of tissue heating from an effect on recorded electrograms or the arrhythmia can be used to guide ablation energy. Guidelines for adjusting power delivery and avoiding "pops" and coagulum formation are suggested.

Animals↗

Effects of beta-hydroxy beta-methylbutyrate on power performance and indices of muscle damage and stress during high-intensity training.

Twenty-six members of a collegiate football team were randomly assigned to either a supplement (S) (3 g of beta-hydroxy beta-methylbutyrate [HMB] per day) or placebo (P) group. Testing occurred before (PRE) and at the end of 10 days of preseason football training camp (POST). During each testing session, subjects performed an anaerobic power test, and blood samples were obtained for testosterone, cortisol, creatine kinase, and myoglobin analysis. No differences in anaerobic power were seen between PRE and POST in either group. Cortisol concentrations were significantly decreased from PRE (333 +/- 81 nmol.L(-1)) to POST (246 +/- 79 nmol.L(-1)), and a sixfold increase was seen in creatine kinase concentrations at POST. However, no significant differences between the groups were seen. No significant time or group effects were observed in testosterone or myoglobin concentrations. Results suggest that short duration HMB supplementation does not provide any ergogenic benefit in collegiate football players during preseason training camp.

Administration, Oral↗

Comparison of Olympic vs. traditional power lifting training programs in football players.

Twenty members of an National Collegiate Athletic Association Division III collegiate football team were assigned to either an Olympic lifting (OL) group or power lifting (PL) group. Each group was matched by position and trained 4-days.wk(-1) for 15 weeks. Testing consisted of field tests to evaluate strength (1RM squat and bench press), 40-yard sprint, agility, vertical jump height (VJ), and vertical jump power (VJP). No significant pre- to posttraining differences were observed in 1RM bench press, 40-yard sprint, agility, VJ or in VJP in either group. Significant improvements were seen in 1RM squat in both the OL and PL groups. After log10-transformation, OL were observed to have a significantly greater improvement in Delta VJ than PL. Despite an 18% greater improvement in 1RM squat (p > 0.05), and a twofold greater improvement (p > 0.05) in 40-yard sprint time by OL, no further significant group differences were seen. Results suggest that OL can provide a significant advantage over PL in vertical jump performance changes.

Football↗

Comparison between linear and nonlinear in-season training programs in freshman football players.

The purpose of this study was to compare linear (LT) with nonlinear (NL) in-season training programs in freshman football players during the course of 2 separate seasons. During the first year (n = 14, mean +/- SD = 177.3 +/- 4.8 cm, 88.0 +/- 9.7 kg), the LT program was employed 2 days per week. In the second year (n = 14, 175.0 +/- 7.1 cm, 94.2 +/- 20.5 kg), a 2 days per week LT was used. Subjects were tested for maximal strength in the squat (1 repetition maximum [1RM]) and bench press (1RM) exercises. A significant improvement in 1RM squat was seen in LT, but not in NL. No significant improvement in 1RM bench press was seen in either group. A significant difference between LT and NL was observed in Delta1RM squat (13.8 +/- 7.4 kg compared with 1.6 +/- 2.6 kg, respectively). Results of this study suggest that LT may be more effective in eliciting strength gains than NL in freshman football players during an in-season training program.

Adolescent↗