Tracking heart surface features to determine myocardial contrast agent enrichment

Fluorescent cardiac imaging can be applied for intraoperative quality control after a coronary bypass grafting surgery to ensure the myocardial perfusion by evaluating the increasing contrast agent enrichment in the heart. The motion due to the beating heart impedes the interpretation of the contrast agent enrichment in the vessels and leads to noisy enrichment curves. We propose tracking of the heart surface features to compensate for the motion of the beating heart and thereby improve the analysis of the contrast agent enrichment. Furthermore, we propose a vessel segmentation pipeline for a local evaluation of contrast agent enrichment directly in the vessels.

[Maturation of the autonomic nervous system: differences in heart rate variability at different gestational weeks]

AIMS

Heart rate variability (HRV) reveals information on the functional state of the autonomic nervous system (ANS). This study was initiated to assess the physiological and maturational development of the ANS by comparing HRV data of a large number healthy foetus of different gestational ages from the 24(th) to the 42(nd) week.

METHODS

Cardiotocogram (CTG) recordings of HRV of 172 healthy foetus (24-42 weeks' gestation) were performed to establish normative data. Frequency domain HRV parameters were computed in three frequency bands.

RESULTS

The gestational ages of the foetuses correlate with HRV. Lower gestational age in weeks showed lower frequency domain parameters than higher gestational age in weeks. The most significant differences were discerned for HRV parameters reflecting sympathetic activity in LF (low frequency) and VLF (very low frequency), due to the adrenergic system.

CONCLUSIONS

Maturation of the ANS is accompanied by increasing HRV with a pronounced increase of sympathetic activity. These changes are measurable by CTG recordings with a computer algorithm which can calculate short-term variability on the basis of CTG data. Problems of the CTG signal, as shown before, were the parameters of the time domain, which could only be well detected by ECG or foetal magnetocardiography (FMCG).

Larva-adult relationships in an ancestral dipteran: A re-examination of sensillar pathways across the antenna and leg anlagen of Chaoborus crystallinus (DeGeer, 1776; Chaoboridae)

In one of his classical studies on insect metamorphosis, Weismann compared the imaginal anlagen of the ancestral phantom midge, Chaoborus, with those of advanced brachycerans. We have expanded his findings on the relationships between larval and imaginal organs using electron microscopy and cobalt backfilling of the antenna and leg anlagen and the axonal trajectories of corresponding larval sensilla. We show that both primordia are confluent with the larval antennae and "leg" sensilla (an ancestral Keilin organ), respectively. These fully developed larval organs represent the distal tips of the imaginal anlagen rather than separate cell clusters. The axons of the larval antenna and leg sensilla project across the corresponding anlagen to their target neuromeres within the central nervous system (CNS). Within the discs, nerves composed of these larval axons, developing afferent fibres and efferences ascending from the CNS are found. Both the structure of the primordia and the axonal trajectories thus relate the situation found in advanced brachycerans with that seen in more ancestral insects. In addition, the larval antennae, legs, wings and even the eyes possess very similar afferent pioneer trajectories supporting the idea that the described pattern is generally used in the ontogeny of sensory systems.