Optimization of Catheter Ablation of Atrial Fibrillation: Insights Gained from Clinically-Derived Computer Models

Atrial fibrillation (AF) is the most common heart rhythm disturbance, and its treatment is an increasing economic burden on the health care system. Despite recent intense clinical, experimental and basic research activity, the treatment of AF with current antiarrhythmic drugs and catheter/surgical therapies remains limited. Radiofrequency catheter ablation (RFCA) is widely used to treat patients with AF. Current clinical ablation strategies are largely based on atrial anatomy and/or substrate detected using different approaches, and they vary from one clinical center to another. The nature of clinical ablation leads to ambiguity regarding the optimal patient personalization of the therapy partly due to the fact that each empirical configuration of ablation lines made in a patient is irreversible during one ablation procedure. To investigate optimized ablation lesion line sets, in silico experimentation is an ideal solution. 3D computer models give us a unique advantage to plan and assess the effectiveness of different ablation strategies before and during RFCA. Reliability of in silico assessment is ensured by inclusion of accurate 3D atrial geometry, realistic fiber orientation, accurate fibrosis distribution and cellular kinetics; however, most of this detailed information in the current computer models is extrapolated from animal models and not from the human heart. The predictive power of computer models will increase as they are validated with human experimental and clinical data. To make the most from a computer model, one needs to develop 3D computer models based on the same functionally and structurally mapped intact human atria with high spatial resolution. The purpose of this review paper is to summarize recent developments in clinically-derived computer models and the clinical insights they provide for catheter ablation.     

Metastatic breast cancer presenting as heel pain

The authors present a case of breast cancer metastasizing to the calcaneus that was confirmed by bone biopsy. The patient's complaint of heel pain provided the initial evidence of skeletal metastasis. Metastatic spread of cancer to the hand or foot (acrometastasis) is considered rare. However, the possibility of acrometastasis should be considered in any patient with a history of cancer presenting with skeletal pain, especially if the symptoms do not respond to therapy.     

Heterologous expression of the lactacin F peptides by Carnobacterium piscicola LV17

The lactacin F complex, composed of LafA and LafX peptides, is produced by Lactobacillus johnsonii VPI 11088 and is active against five other Lactobacillus species and Enterococcus faecalis. The genetic determinants encoding the lactacin F complex are organized in a 1-kb polycistronic operon which comprises three genes, lafA, lafX, and ORFZ (encoding the putative immunity protein). The lafA and lafX genes encode the bacteriocin precursors with N-terminal extensions characterized by a Gly-Gly-1*Xaa+1 cleavage site (*). The Gly-Gly motif is conserved in several other bacteriocins, including carnobacteriocins A, BM1, and B2. Carnobacterium piscicola LV17 produces carnobacteriocins which are active against Listeria monocytogenes and other lactic acid bacteria. In this study, the lactacin F operon was introduced into C. piscicola LV17. The transformants produced lactacin F concurrently with the carnobacteriocins. When the lafA and lafX genes were separated and cloned individually into LV17, production of either LafA or LafX by C. piscicola LV17 was detected by complementation with L. johnsonii clones producing LafX or LafA, respectively. Transformants of C. piscicola LV17 which produced lactacin F, LafA, or LafX, in combination with the carnobacteriocins, were assayed for an increased and expanded inhibitory spectrum. The recombinant organisms were only active against lactacin F- and carnobacteriocin-sensitive strains. A plasmidless derivative of LV17 which does not produce the carnobacteriocins failed to produce lactacin F, LafA, or LafX when transformed with the appropriate recombinant plasmids. The ability of C. piscicola LV17 to produce lactacin F demonstrates that the machinery for the carnobacteriocins is capable of processing and exporting bacteriocins from both systems.     

Developmental change in children's analysis of spatial patterns.

This study examines the early development of spatial pattern analysis and focuses on changes in the way that preschool children (3–5 yr olds) segment and integrate the parts of simple spatial forms. The results from each of the 3 experiments in this study show that young children analyze spatial patterns in ways that differ systematically from that of older children and adults. Changes with development were observed in the parts children segmented out of the forms and in the relations they used to organize the parts forming the overall pattern. The youngest children segmented out simple, well-formed, spatially independent parts and used simple relational structures to bind these parts together. With development, children constructed forms that included increasingly complex parts and relations. These findings were consistent across several different stimuli using 2 construction mediums. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial analysis: An examination of preschoolers' perception and construction of geometric patterns.

An extensive series of construction-based studies have shown that children as young as 3 yrs of age engage in active spatial analytic processing and that the character of this analysis changes with development. The present study was intended to demonstrate that this kind of analysis is not limited to situations that require reproduction. Children 3.5–5 yrs of age were asked to judge which of several possible sets of parts matched a configured target form. They were also asked to copy the target forms. Comparison of performance on the 2 tasks demonstrated that the same developmental trends seen in the copying task were exhibited in the perceptual judgment task. This was true for both simple linear and more varied forms. Thus, this task provides important converging evidence that in perceptual judgment as well as construction tasks children engage in active analysis of the visual display. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Early sudden gains in psychotherapy under routine clinic conditions: Practice-based evidence.

Sudden gains---large, enduring reductions in symptom intensity from one session to the next--were identified by T. Z. Tang and R. J. DeRubeis (1999) on the basis of data from 2 manualized clinical trials of cognitive therapy for depression. The authors found similar sudden gains among clients with a variety of disorders treated with a variety of approaches in routine clinic settings. Clients (N=135 who met inclusion criteria) completed short forms of the Clinical Outcomes in Routine Evaluation (CORE-SF) preceding 7 to 74 individual sessions. Those who experienced sudden gains within their first 16 sessions (n=23) had significantly lower CORE-SF scores in their final 3 sessions than did the other clients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Counselor-client agreement on session impact.

We propose a new framework for understanding studies of counselor–client agreement about their counseling. The framework includes five factors: the scope of counseling being studied (process, impact, or outcome), the dimension (index) being rated (in this study, session Depth, Smoothness, Positivity, or Arousal), the measure used to assess agreement (correlations or absolute differences), the level at which the analysis is conducted (session, client, or counselor), and the type of agreement—(a) consensus, the similarity of counselors' own ratings to clients' own ratings; (b) counselor awareness, the similarity of counselors' perceptions of their clients to clients' own ratings; (c) client awareness, the similarity of counselors' own ratings to clients' perceptions of their counselors; and (d) matched awareness, the similarity of counselors' perceptions of their clients to clients' perceptions of their counselors. In a study of session impact (scope), degree of agreement was found to vary substantially with each of the other factors—type of agreement, dimension rated, measure of agreement, and level of analysis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)