P1133Impact of mid-septal versus apical pacing on the right ventricle performance of patients with right bundle branch block undergoing pacemaker implantation

Background pacemaker induced cardiomyopathy or transient impairment of the left ventricle (LV) function could be common collateral effects of the prolonged right ventricle (RV) pacing in patients with a pacemaker (PM) and pre-existing intra-ventricular conduction disturbances. However, the impact of RV pacing-site on RV performance of patients with right bundle branch block(RBBB) is still under-investigated. Purpose to study the effects of RV pacing in the mid-septal versus apical site on the morpho-functional performance of RV in patients undergoing permanent PM implantation. Methods We prospectively enrolled consecutive patients with a pre-existent complete RBBB and undergoing dual-chamber PM implantation in our institution. We randomized the patients 1:1 to receive the RV catheter fixed either in the apex or in the mid-septal position. Patients with LV systolic dysfunction (LVEF <50%), severe valvulopathies, left bundle branch block (LBBB), or preserved intraventricular conduction were excluded. Patients who received PM implantation were evaluated both at baseline and after two months with a 12-lead ECG, 2D, and 3D echocardiogram with analysis focused on RV performance according to the guidelines of the European Association of Cardiovascular Imaging. Results a total of 22 patients were randomized in the study, 11 (50%) received RV catheter positioned in the apex and 11 (50%) in the mid-septum, respectively. No baseline differences were recorded between the two groups in clinical characteristics, ECG and echocardiographic parameters. At 2 months follow up, there were no statistically significant difference in the % of RV pacing between the two groups. Nonetheless, RV mid-septal group showed significantly shorter duration of the stimulated QRS (146 ± 12 msec vs. 161 ± 20 msec, p = 0.05), significantly reductions in the RV dimensions (pre: 42 ± 8 mm vs. post: 37 ± 7 mm, p = 0.05) telediastolic area (pre: 12 ± 3 cm2/m2 vs post: 9 ± 4 cm2/ m2, p = 0.02) telediastolic volume (pre: 55 ± 16 ml/m2 vs post: 50 ± 17 ml/m2, p = 0.02) and a significant improvement of RV ejection fraction (pre: 54 ± 9% vs post: 57 ± 11%, p = 0.02) than patients in the RV-apical group. Moreover, patients in the RV-apical group showed significant lowering in the GLS of the LV (pre: -16 ± 3% vs post: -11.7 ± 3%, p <0.001) and in the TAPSE (pre: 23 ± 5 mm vs post: 21 ± 2, p = 0.07) at follow up. Conclusions In this study, mid-septal pacing seems associated with a better morpho-functional RV performance than apical pacing in patients with pre-existent RBBB undergoing permanent PM implantation.

Longitudinal strain and strain rate by tissue Doppler are more sensitive indices than fractional shortening for assessing the reduced myocardial function in asphyxiated neonates

The function of the heart was studied in 20 asphyxiated term neonates by measuring the longitudinal peak systolic strain and peak systolic strain rate by tissue Doppler in 18 segments of the heart on days 1, 2, and 3 of life. The fractional shortening was assessed at each examination as well. Measurements were compared against measurements in 48 healthy term neonates examined by the same protocol. The function of the heart was lower in the asphyxiated neonates – peak systolic strain (mean (95% confidence interval) −19.4% (−20.4, −18.5), peak systolic strain rate −1.65 (−1.74, −1.56) per second) than in the healthy term neonates (peak systolic strain −21.7% (−22.3, −21.0), peak systolic strain rate −1.78 (−1.84, −1.74) per second; p < 0.001). Fractional shortening was similar in the asphyxiated (29.2% (26.8, 31.5)) and healthy term neonates (29.0% (27.9, 30.1); p = 0.874). The peak systolic strain differed significantly between the asphyxiated and healthy term neonates for the left basal and right basal groups of segments (p < 0.05) but not for the left apical, right apical, septum apical, or septum basal groups of segments. The peak systolic strain rate differed significantly only for the septum apical group of segments. The differences were largest on the second day of life. Measurements were similar in asphyxiated neonates with elevated and normal cardiac troponin T levels. The peak systolic strain and strain rate were in this study more sensitive indices than fractional shortening for assessing the reduced myocardial function in asphyxiated term neonates.

Cranial structure in the Devonian lungfish Soederberghia groenlandica and its implications for the interrelationships of ‘rhynchodipterids’

ABSTRACTNew cranial material of the ‘rhynchodipterid’ lungfishSoederberghia groenlandicafrom Upper Devonian (Famennian) strata in East Greenland is described. Previously unknown structures identified here include components of the hyoid arch (ceratohyal, hypohyal) and the lower jaw (prearticular, dentary). Earlier interpretations of the cheek and mandible ofSoederberghiaare reconsidered in the light of new fossil specimens. Some of the difficulties in assessing the homologies between cheek bones inSoederberghiaand those of other lungfishes stem from confusion over the arrangement inRhynchodipterus, and a revised interpretation of this genus is proposed. The single infraorbital bar found inSoederberghiaprobably originates, in part, from an expanded bone 10 (quadratojugal) of the kind found inGriphognathus. Hypotheses that posit ‘rhynchodipterid’ polyphyly seem unlikely in light of a set of derived cranial characters that define a coherent radiation of long-snouted, denticle-bearing lungfishes known from the Late Devonian. The hypothesis presented here places ‘rhynchodipterids’ as a paraphyletic grade with respect to fleurantiids.Rhynchodipterus,Soederberghia, and fleurantiids form a clade to the exclusion of the species ofGriphognathus.G. minutidensis the sister taxon to this apical group, whileG. sculptaandG. whiteiare more remote from it.

Phylogenetic relationships and biogeographic considerations of four new species of Cnemalobus (Coleoptera: Carabidae) from Patagonia

Four new species of Cnemalobus Guérin-Ménéville, 1838 (Carabidae) from the northern steppe of Patagonia and extra-Andean mountains are described in this work. Two of these species, Cnemalobus nevado sp. n. and Cnemalobus diamante sp. n., are from the Payunia (Argentina), the northernmost region of Patagonia. One species, C. somuncura sp. n., is from the vicinity of the Somuncurá Plateau. The other species, Cnemalobus troll sp. n., is from the northwestern steppe. Illustrations and keys for these new species are provided. The phylogenetic relationships among the new species were defined using a cladistic analysis for the genus Cnemalobus, based on 56 characters of the external morphology and male and female genitalia. The cladogram showed that C. nevado sp. n. and C. diamante sp. n. comprise a monophyletic group that is the adelphotaxon of an apical clade of species that mainly inhabit mountain habitats in central Chile. Cnemalobus somuncura sp. n. and C. troll sp. n. are also sister species and comprise the apical group of the Patagonian species. Cnemalobus nevado and C. diamante occur in the Payunia, and their distribution is restricted to different mountains and are isolated from each other. Given that these two mountains are 200 km apart, it is not likely that dispersal has occurred in these large and flightless species. The ancestral species might have been broadly distributed, and, as a result of habitat changes, they became isolated into restricted habitats in the upper part of each mountain, where speciation might have occurred. The other two new species, C. somuncura and C. troll, are placed in the group of Patagonian species that inhabit the lowlands or plateaus. Distributional data, together with phylogeny, showed that the sister species of Cnemalobus have an allopatric distribution. Strict sympatry (same locality) occurs in the northwestern region of the Patagonian Steppe. Nevertheless, this strict sympatry may be an artifact of geographical scale. For example, within the same area, some species may inhabit grasslands next to forests, while other species inhabit only steppe areas.

Echinobothrium acanthinophyllum, n.sp. from the spiral valve of Raja montagui Fowler

1. Echinobothrium acanthinophyllum sp.nov. occurs in the spiral valve of Raja montagui Fowler. E. affine Diesing was also present.2. E. acanthinophyllum possesses 23 large hooks in each apical group flanked by 4 small hooks on either side. There are 13 spines in each of the 8 longitudinal rows on the cephalic peduncle and 13 testes in each proglottid. The ripe eggs aggregate into clusters of 8–10, which fill the gravid uterus.3. Euzet's key is revised to include the 9 species of the genus.