Linda P. Nelson

Results of the PROspective MInnesota Study of ECHO/TDI in Cardiac Resynchronization Therapy (PROMISE-CRT) Study

BACKGROUND Retrospective single-center studies have shown that measures of mechanical dyssynchrony before cardiac resynchronization therapy (CRT), or acute changes after CRT, predict response better than QRS duration. The Prospective Minnesota Study of Echocardiographic/TDI in Cardiac Resynchronization Therapy (PROMISE-CRT) study was a prospective multicenter study designed to determine whether acute (1 week) changes in mechanical dyssynchrony were associated with response to CRT. METHODS AND RESULTS Nine Minnesota Heart Failure Consortium centers enrolled 71 patients with standard indications for CRT. Left ventricular (LV) size, function, and mechanical dyssynchrony (echocardiography [ECHO], tissue Doppler imaging [TDI], speckle-tracking echocardiography [STE]) as well as 6-minute walk distance and Minnesota Living with Heart Failure Questionnaire scores were measured at baseline and 3 and 6 months after CRT. Acute change in mechanical dyssynchrony was not associated with clinical response to CRT. Acute change in STE radial dyssynchrony explained 73% of the individual variation in reverse remodeling. Baseline measures of mechanical dyssynchrony were associated with reverse remodeling (but not clinical) response, with 4 measures each explaining 12% to 30% of individual variation. CONCLUSIONS Acute changes in radial mechanical dyssynchrony, as measured by STE, and other baseline mechanical dyssynchrony measures were associated with CRT reverse remodeling. These data support the hypothesis that acute improvement in LV mechanical dyssynchrony is an important mechanism contributing to LV reverse remodeling with CRT.

Addressing Dental Fear in Children With Autism Spectrum Disorders: A Randomized Controlled Pilot Study Using Electronic Screen Media

Background. Dental care is a significant unmet health care need for children with autism spectrum disorders (ASD). Many children with ASD do not receive dental care because of fear associated with dental procedures; oftentimes they require general anesthesia for regular dental procedures, placing them at risk of associated complications. Many children with ASD have a strong preference for visual stimuli, particularly electronic screen media. The use of visual teaching materials is a fundamental principle in designing educational programs for children with ASD. Purpose. To determine if an innovative strategy using 2 types of electronic screen media was feasible and beneficial in reducing fear and uncooperative behaviors in children with ASD undergoing dental visits. Methods. We conducted a randomized controlled trial at Boston Children’s Hospital dental clinic. Eighty (80) children aged 7 to 17 years with a known diagnosis of ASD and history of dental fear were enrolled in the study. Each child completed 2 preventive dental visits that were scheduled 6 months apart (visit 1 and visit 2). After visit 1, subjects were randomly assigned to 1 of 4 groups: (1) group A, control (usual care); (2) group B, treatment (video peer modeling that involved watching a DVD recording of a typically developing child undergoing a dental visit); (3) group C, treatment (video goggles that involved watching a favorite movie during the dental visit using sunglass-style video eyewear); and (4) group D, treatment (video peer modeling plus video goggles). Subjects who refused or were unable to wear the goggles watched the movie using a handheld portable DVD player. During both visits, the subject’s level of anxiety and behavior were measured using the Venham Anxiety and Behavior Scales. Analyses of variance and Fisher’s exact tests compared baseline characteristics across groups. Using intention to treat approach, repeated measures analyses were employed to test whether the outcomes differed significantly: (1) between visits 1 and 2 within each group and (2) between each intervention group and the control group over time (an interaction). Results. Between visits 1 and 2, mean anxiety and behavior scores decreased significantly by 0.8 points (P = .03) for subjects within groups C and D. Significant changes were not observed within groups A and B. Mean anxiety and behavior scores did not differ significantly between groups over time, although group A versus C pairwise comparisons showed a trend toward significance (P = .06). Conclusion. These findings suggest that certain electronic screen media technologies may be useful tools for reducing fear and uncooperative behaviors among children with ASD undergoing dental visits. Further studies are needed to assess the efficacy of these strategies using larger sample sizes. Findings from future studies could be relevant for nondental providers who care for children with ASD in other medical settings.

Correlation of impedance minute ventilation with measured minute ventilation in a rate responsive pacemaker.

COLE, C.R., et al.: Correlation of Impedance Minute Ventilation with Measured Minute Ventilation in a Rate Responsive Pacemaker. Although rate responsive pacing based on impedance minute ventilation (IMV) is now standard, there is almost no data confirming the relationship between IMV from an implanted pacemaker and measured minute ventilation (VE) during exercise. Nineteen completely paced adults implanted with Medtronic Kappa 400 pacemakers underwent symptom‐limited maximal metabolic treadmill testing using a modified Minnesota Pacemaker Response Protocol. Minute ventilation (VE, L/min) was simultaneously measured using the flowmeter of a respiratory metabolic gas analysis system and the transthoracic impedance minute ventilation circuitry of the pacemaker. Correlation coefficients (r) were used to find the best fit line to describe the relationship between the two measurements. Mean (± SD) r values for the first, second, and third order polynomial equations and for log and exponential equations were: 0.92 ± 0.08, 0.94 ± 0.04, 0.95 ± 0.04, 0.91 ± 0.06, and 0.91 ± 0.07, respectively. None of the r values were statistically different from the first order equation. Transthoracic IMV as measured by the Medtronic Kappa 400 is closely correlated to measured minute ventilation and is represented well by a first order (linear) equation.

Influence of Posture, Breathing Pattern, and Type of Exercise on Minute Ventilation Estimation by a Pacemaker Transthoracic Impedance Sensor

Previous studies have shown a high correlation between transthoracic impedance minute ventilation (IMV) determined by a pacemaker sensor and actual minute ventilation (VĖ) measured by standard methods. We hypothesized that several factors (e.g., posture, breathing pattern, and exercise type) could potentially affect the calibration between IMV and VĖ. In patients with Medtronic Kappa 400 pacemakers, VĖ (L/min) was monitored using a standard cardiopulmonary metabolic gas analysis system with simultaneous recording of IMV (ohms/min) using DR‐180 extended telemetry monitors. Effects of posture and of breathing pattern at rest (19 patients; age 60 ± 13 years) were evaluated by monitoring each patient under three conditions: (a) slow breathing, supine, (b) slow breathing, sitting, and (c) shallow breathing, supine. Calibration at rest was defined as the ratio of IMV to VĖ. Effect of type of exercise on calibration compared treadmill versus graded bicycle ergometer exercise (18 patients; age 62 ± 14 years). Calibration during exercise was defined as: (a) “Begin” (the IMV to VĖ ratio at VĖ =10 L/min, the typical VĖ value at beginning of exercise), and (b) slope of the IMV/VĖ regression line. Calibration of IMV/VĖ was significantly smaller for sitting versus supine position (0.7130.177, P ≤ 0.001) and for shallow versus slow breathing (0.7210.373, P < 0.001), and larger for treadmill versus bicycle exercise (Begin: 1.240.43, P = 0.018; Slope: 1.260.42, P = 0.013). In conclusion, posture, breathing pattern, and type of exercise affect the IMV estimation of the actual VĖ, possibly by altering the static or dynamic geometry (thus, the impedance) of the intrathoracic viscera.

Emergency management of oral trauma in children.

Oral trauma continues to be a common pediatric emergency, accounting for 150 emergency room dental consultations per year at Childrens Hospital in Boston. Children between the ages of 18 months and 2.5 years and between 8 and 11 years are most at risk. Recent advances in the management of these dental emergencies may help children and their families avoid the psychological and financial cost of infection or loss of primary and permanent teeth. Treatment of avulsions in the young permanent dentition remains a common problem, and a universally accepted approach to its management is still evolving. The use of a doxycycline immersion prior to reimplantation by the dentist may be helpful in preventing external root resorption. As always, the best therapy against dentofacial trauma is the pediatricians support of preventive measures.