Hybrid solid-state SPECT/CT left atrial innervation imaging for identification of left atrial ganglionated plexi: Technique and validation in patients with atrial fibrillation.

BACKGROUND: Ablating left atrial (LA) ganglionated plexi (GP), identified invasively by high-frequency stimulation (HFS) during pulmonary vein isolation (PVI), may reduce atrial fibrillation (AF) recurrence. 123I-metaiodobenzylguanidine (123I-mIBG) solid-state SPECT LA innervation imaging (LAII) has the spatial resolution to detect LAGP non-invasively but this has never been demonstrated in clinical practice. METHODS: 20 prospective patients with paroxysmal AF scheduled for PVI underwent 123I-mIBG LAII. High-resolution tomograms, reconstructed where possible using cardiorespiratory gating, were co-registered with pre-PVI cardiac CT. Location and reader confidence (1 [low] to 3 [high]) in discrete 123I-mIBG LA uptake areas (DUAs) were recorded and correlated with HFS. RESULTS: A total of 73 DUAs were identified, of which 59 (81%) were HFS positive (HFS +). HFS + likelihood increased with reader confidence (92% [score 3]). 64% of HFS-negative DUAs occurred over the lateral and inferior LA. Cardiorespiratory gating reduced the number of DUAs per patient (4 vs 7, P = .001) but improved: HFS + predictive value (76% vs 49%); reader confidence (2 vs 1, P = .02); and inter-observer, intra-observer, and inter-study agreement (κ = 0.84 vs 0.68; 0.82 vs 0.74; 0.64 vs 0.53 respectively). CONCLUSIONS: 123I-mIBG SPECT/CT LAII accurately and reproducibly identifies GPs verified by HFS, particularly when reconstructed with cardiorespiratory gating.

Conscious and anesthetized non-human primate safety pharmacology models: hemodynamic sensitivity comparison.

INTRODUCTION: Drug-induced cardiovascular effects identified in conscious cynomolgus monkeys equipped with tethers and prepared for radiotelemetry were compared with results from anesthetized non-human primate (cynomolgus and rhesus) models. METHODS: Remifentanil (4.0 microg/kg, bolus), esmolol (2.0 mg/kg, bolus) and dopamine (0.05 mg/kg/min, 30 min infusion) were given intravenously to all models. RESULTS: Remifentanil decreased heart rate (HR), systolic, mean and diastolic systemic arterial pressures (SAP) in anesthetized animals while conscious monkeys presented an increase in HR, systolic, mean and diastolic SAP, as seen in humans for the respective state of consciousness (conscious and anesthetized). Esmolol decreased HR, systolic, mean and diastolic SAP in anesthetized monkeys while only HR, systolic and mean SAP achieved a statistically significant decrease in the conscious model. The amplitude of SAP reduction was greater in anesthetized models, while the amplitude of HR reduction was greater in the conscious and anesthetized cynomolgus models than in the anesthetized rhesus model. Dopamine induced a significant increase in HR, systolic, mean and diastolic SAP in anesthetized models without any statistically significant effect on HR and SAP in the conscious model. DISCUSSION: The amplitude of hemodynamic and chronotropic alterations induced by positive control drugs was generally greater in anesthetized than in conscious models and statistical significance was achieved more often with the anesthetized models. These results suggest that an anesthetized model may be valuable as part of a drug screening program for cardiovascular safety evaluations in addition to a conscious model.

Determining baseline and adaptation periods in stress research.

Investigations pertaining to psychophysiological stress responses typically employ a preexperimental 'baseline' period. The appropriateness of this methodology was examined in two studies using heart rate (HR) measures. In study 1, HR decreased significantly from the beginning to the end of a 15-min adaptation period, suggesting that the optimal length for a prestress adaptation period must be at least 15 min for HR when a stressor is anticipated. Study 2 compared the customary prestress 'baseline' measure to four other possible candidates: two recovery periods between stressor presentations, a postexperimental time period, and a recording taken on a different day when no stressors were presented. The prestress measure was significantly higher than recovery and postexperimental measures. The postexperimental measure was retained as the best option for the computation of a baseline score. These studies highlight the factors pertinent to the selection of a suitable time frame for a baseline measure.

Effect of intertrial intervals on recovery and amplitude of electrodermal reactions.

Convincing findings have been published about the importance of prior activity on electrodermal recovery. However, these studies mainly used tone tasks as an experimental paradigm. The present research investigated the influence of prior activity by changing the intertrial intervals (ITI) in cognitive and reaction time tasks. Results indicated that ITI had no effect on amplitude but had a significant effect on recovery time, a longer ITI period producing a longer recovery curve. No correlation was found between recovery and amplitude. Analysis also indicated that variable intervals should not be recommended between the tasks. These observations emphasize the importance of prior activity on electrodermal recovery in more complex tasks.

Supraventricular tachycardia in an infant.

Treating this 1-month-old infant with SVT with adenosine was extremely effective and resulted in no observable side effects to the patient. More research needs to be performed and documented regarding the effectiveness and safety of this drug in pediatric patients. Emergency nurses should familiarize themselves with adenosine and should suggest its use in pediatric patients with SVT that does not respond to vagal maneuvers.

Validation of the Derogatis Stress Profile using laboratory and real world data.

The Derogatis Stress Profile (DSP) is unique among the numerous measures of 'stress' in that it incorporates the interactional model of Lazarus and Folkman in a multidimensional structure. Derogatis has studied the psychometric properties of the DSP but its validity has not been demonstrated in the 'real world' nor has it been related to psychophysiological data. The present investigation was aimed at testing the validity of the DSP in these two areas. Forty-three men between the ages of 18 and 30 years completed the DSP, the Daily Hassles Scale (DHS), the Life Experiences Survey (LES), the Profile of Mood States (bipolar form), and the Jackson Personality Inventory (JPI). Participants were exposed to stressors in a laboratory setting as well as in the field while their heart rate was being monitored. Results supported the validity of the DSP, in part. The correlation between the DSP and JPI anxiety scores was significant as was the correlation between the DSP and the daily depression scores. The correlation between the Total Stress Score (TSS) of the DSP and DHS was significant as were the correlations between the TSS and LES scores. Moreover, the DSP scores were related to heart rate reactivity both in the laboratory and in the field.

Somatic growth in infants receiving prolonged caffeine therapy.

We have evaluated the longitudinal growth of 28 premature infants who had been treated by prolonged caffeine therapy (mean: 23.8 weeks). Routine follow-up included at least 5 physical examinations with measurement of length, weight and head circumference at the beginning of caffeine therapy, at mid therapy, at the end of the therapy and at 3 and 6 months after therapy. The distribution of the infants on the growth curves according to weight, length and head circumference showed a regular increase in growth parameters. Analysis of variance was highly significant at p less than 0.0001. We conclude that long term caffeine treatment does not adversely influence growth parameters, at least during early infancy.