Septal Channel Research Articles

Retrograde percutaneous coronary intervention of chronic total occlusion via discontinuous septal channels.

The study aims to investigate the safety and feasibility of retrograde CTO intervention via collateral connection grade 0 (CC-0) septal channel and to identify predictors of collateral tracking failure. Guidewire crossing a collateral channel is a critical step for successful retrograde percutaneous coronary intervention (PCI) of chronic total occlusion (CTO). Retrograde PCI was attempted in 122 cases of CTO with CC-0 septal collaterals from December 2018 to May 2021. A hydrophilic polymer coating guidewire was used for crossing all intended CC-0 collaterals. A multivariable logistic regression analysis was performed to identify the predictors of guidewire tracking failure via the CC-0 collaterals. Successful guidewire tracking via CC-0 septal channel was achieved in 98 (80.3%) of 122 cases. The independent predictors of CC-0 septal channel guidewire tracking failure included well-developed non-septal collateral (OR: 5.297, 95% CI: 1.107-25.353, p = 0.037) and the ratio length of posterior descending artery (PDA) versus the distance of PDA ostium to cardiac apex ≤2/3 (OR: 3.970, 95% CI: 1.454-10.835, p = 0.007). Collateral perforation, target vessel perforation, and cardiac tamponade occurred in 5 (4.1%), 3 (2.5%), and 6 (4.9%) cases, respectively. There were no complications requiring emergency cardiac surgery or revascularization of nontarget vessel. Retrograde PCI via CC-0 septal channels with a hydrophilic polymer-coated guidewire is feasible and safe in patients with CTO. Well-developed nonseptal collaterals and short PDA length influence the procedure success and the risk of guidewire tracking failure via CC-0 septal channels.

Cryo-Electron Tomography Reveals the Complex Ultrastructural Organization of Multicellular Filamentous Chloroflexota (Chloroflexi) Bacteria.

The cell biology of Chloroflexota is poorly studied. We applied cryo-focused ion beam milling and cryo-electron tomography to study the ultrastructural organization of thermophilic Roseiflexus castenholzii and Chloroflexus aggregans, and mesophilic “Ca. Viridilinea mediisalina.” These species represent the three main lineages within a group of multicellular filamentous anoxygenic phototrophic Chloroflexota bacteria belonging to the Chloroflexales order. We found surprising structural complexity in the Chloroflexales. As with filamentous cyanobacteria, cells of C. aggregans and “Ca. Viridilinea mediisalina” share the outer membrane-like layers of their intricate multilayer cell envelope. Additionally, cells of R. castenholzii and “Ca. Viridilinea mediisalina” are connected by septal channels that resemble cyanobacterial septal junctions. All three strains possess long pili anchored close to cell-to-cell junctions, a morphological feature comparable to that observed in cyanobacteria. The cytoplasm of the Chloroflexales bacteria is crowded with intracellular organelles such as different types of storage granules, membrane vesicles, chlorosomes, gas vesicles, chemoreceptor-like arrays, and cytoplasmic filaments. We observed a higher level of complexity in the mesophilic strain compared to the thermophilic strains with regards to the composition of intracellular bodies and the organization of the cell envelope. The ultrastructural details that we describe in these Chloroflexales bacteria will motivate further cell biological studies, given that the function and evolution of the many discovered morphological traits remain enigmatic in this diverse and widespread bacterial group.

129Magnetic resonance predictors of ventricular tachycardia recurrence after radiofrequency substrate ablation: septal and transmural channels

Abstract Ventricular tachycardia (VT) substrate-based ablation has become a gold standard in patients with structural heart disease. Success of VT ablation is related with mortality reduction. Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) is a powerful technique to assess substrate of VT. Myocardial fibrosis is electrically inert (Core) but it is surrounded by a ‘‘border-zone (BZ)’’ where normal cardiomyocytes intermingle with dense bundles of fibrosis. Slow impulse conduction in the BZ allows for the re-entry circuits leading to VT. Both the presence and extent of LGE have been associated with VT and SCD risk. LGE-CMR tissue characterization can be depicted as pixel signal intensity (PSI) maps and can guide VT ablation. The aim of this study was to analyze possible VT recurrence predictors in a long term follow-up of patients that underwent VT ablation (endo and/or epicardial) related with LGE-CMR PSI maps. We analyzed 234 consecutive patients (age: 63.2 ± 14 years, follow-up: 3.14 years ±1.8) undergoing VT ablation with scar-dechannelling technique at a single center from 2013 to 2018. 110 patients underwent a preprocedural LGE-CMR, and in 94 patients (85,5%) a CMR-aided ablation using the PSI maps was performed. All LGE-CMR images were semi-automatically processed using a dedicated software. PSI-based algorithm was applied to characterize the hyperenhanced area as core or BZ, using fixed threshold of the maximum intensity. A LV 3D shell was obtained and were imported into the navigation system. In the PSI maps, heterogenous tissue channels were defined as a continuous corridor of BZ surrounded by scar core or an anatomic barrier that connects 2 areas of healthy tissue. Results Overall recurrence of VT was 41.8 %. There was ICD shock reduction, from 43,6% to a 28,2% (ICD shocks before ablation 2,23 ± 7,32, after: 1,10 ± 2,92). Left ventricle mass predicted significantly VT recurrence (Mean 168,3 ± 53,3 vs 152,3 ± 46,4 g, HR 1,02 [1,01-1,02], p < 0.001). LGE distribuition was predictive of VT recurrence when a more than 40% of the interventricular septum was involved (62,5% vs 37,8%; HR 1,6 [1,01-1,02]; p = 0,044). No differences in recurrence were found among the patterns of LGE distribution (transmural/epicardial/subendocardial or peculiar segments localizations). The amount of BZ and the total amont of Core + BZ was related with VT recurrence (BZ 26,6 ± 13,9 vs 19,56 ± 9,69 g, HR 1,03 [1,01-1,06], p = 0,012; total Core + BZ 37,1 ± 18,2 vs 29,0 ± 16,3 g, HR 1,02 [1,00-1,04], p = 0,033). Finally VT recurrence was higher in patients with channels with transmural path (66,7% vs 31,4%, HR 3,25 [1,70-6,23], p < 0,001) or midmural channels (54,3% vs 27,6%, HR 2,49 [1,21–5,13], p = 0,013). CMR-aided scar dechanneling is a helpful and feasible technique which could identify patients with high risk of VT recurrence. High left ventricular mass, septal LGE distribution, transmural and midmural heterogeneous tissue channels were predictive factors of post ablation VT recurrence. Abstract Figure. VTchannel & heterogeoneus tissue channel

Right Coronary Artery Neo-Ostium Created Via Retrograde Wire Crossing

A 79-year-old woman with prior stent implantation for the right coronary artery 8 years ago was diagnosed with right coronary artery occlusion ([Figures 1A and 1B][1], [Online Videos 1][2] and [2][3]). Due to the absence of an ostium stump, a primary retrograde approach via the septal channel was

Safety and effectiveness of the surfing technique to cross septal collateral channels during retrograde chronic total occlusion percutaneous coronary intervention.

Septal surfing and distal tip injections are two techniques used for septal crossing in retrograde chronic total occlusion (CTO) percutaneous coronary interventions (PCI). The aim of this study was to examine for the first time the safety and feasibility of the septal surfing technique. Among 470 consecutive CTO PCIs performed in the Quebec hybrid CTO PCI program between January 2010 and December 2015, 240 (51%) involved a retrograde attempt. In the septal crossing subgroup, we evaluated whether the Werner collateral channel (CC) classification, CTO location, tortuosity, and number of large septal CCs influenced retrograde crossing success, time, and perforation. Septal channels were used in the majority (n=152, 63%) of cases. Patients in the septal subgroup were younger, had less bypass surgery, were more likely to have RCA CTO and had previous failure. Septal channels were successfully crossed with the wire using the surfing technique in 81%, irrespective of the CC size. Septal crossing success and time were not influenced by Werner CC class but by septal CC tortuosity. One quarter of cases had septal perforations; all were minor and asymptomatic. Septal surfing is a safe and highly successful technique for crossing septal CCs when a retrograde approach is mandated for CTO PCI. The Werner class does not affect retrograde CC crossing success or time.

A pitfall in selecting promising septal collateral channels in percutaneous coronary intervention with a retrograde approach

Introduction: In percutaneous coronary intervention (PCI) with a retrograde approach, successful guide wire passage through the collateral channels is indispensable. However, success of the procedure depends on the quality of collateral channels, and vascular tortuosity is one of the most common obstacles for successful guidewire passage. Case Presentation: Herein, we present a case of PCI with retrograde approach for chronic total occlusion at the ostium of the left anterior descending coronary artery. A highly tortuous morphology of the right posterior descending artery (PDA) and septal channels bifurcating from the right PDA with marked angulations were recognized in angiographic images from multiple directions. We could advance a guidewire to the optimal route of the septal collateral channel with guidance provided by these images and successfully completed all PCI procedures. Conclusions: To pass a guidewire through collateral arteries in PCI with a retrograde approach, careful inspection of angiographic images for thoroughly understanding the optimal route through the collateral vasculature is of great significance.

Complications during retrograde approach for chronic coronary total occlusion: Sub-analysis of Japanese multicenter registry.

This study was performed to determine the complications occurring during retrograde percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) based on analysis of the multicenter, prospective, nonrandomized Retrograde Summit registry. Retrograde PCI for CTO has improved treatment success rates, but several complications related to the retrograde approach have been reported, including collateral channel injury and donor artery injury due to their use as retrograde roots. This registry included data from 1,166 patients who underwent retrograde PCI for CTO in 28 Japanese centers between January 2009 and December 2011. Overall procedure success and retrograde procedure success were achieved in 985 (84.5%) and 838 (71.9%) of the 1,166 patients, respectively. In-hospital major adverse cardiac and cerebrovascular events (MACCE) occurred in 18 (1.5%) of the 1,166 patients. With regard to complications related to the retrograde approach, channel injury occurred in 111 (9.5%) of the 1,166 patients, but treatment was required in only 24 (2.1%) patients and subsequent cardiac tamponade occurred in only 4 (0.3%) patients. Donor artery problems occurred in only 10 (0.9%) of the 1,166 patients. In sub-analysis regarding the types of collateral channels, the septal channel was significantly safer than epicardial channel because of the lower frequency of non-Q-wave myocardial infarction (non-QMI) and channel injury requiring treatment. The MACCE rate during retrograde PCI for CTO determined from the Retrograde Summit registry was low and the frequency of complications related to the retrograde approach was acceptable. © 2015 Wiley Periodicals, Inc.

Coronary perforation with tamponade successfully managed by retrograde and antegrade coil embolization

In recent years, retrograde approach for chronic total occlusions has rapidly evolved, enabling a higher rate of revascularization success. Compared to septal channels, epicardial collaterals tend to be more tortuous, more difficult to negotiate, and more prone to rupture. Coronary perforation is a rare but potentially life-threatening complication of coronary angioplasty, often leading to emergency cardiac surgery. We report a case of a retrograde chronic total occlusion revascularization through epicardial collaterals, complicated by both retrograde and antegrade coronary perforation with tamponade, and successfully managed by coil embolization.

TCT-77 Initial and Mid-Term Angiographic Outcomes of Septal Channel Perforation Related to Retrograde Recanalization for Chronic Total Occlusions

Septal channel perforation occurs rarely in retrograde recanalization via septal channel for chronic total occlusion (CTO) lesions. There has been little data on mid-term angiographic outcomes of septal channel perforation. Septal channel perforation with cardiac tamponade or spreading myocardial

Percutaneous coronary intervention by retrograde approach for chronic total occlusion of the proximal left anterior descending artery via a gastroepiploic artery graft

Coronary arteries connecting to septal branch are often occluded in post-coronary artery bypass graft cases. A 70-year-old male had undergone CABG; radial artery graft to the LCX, and gastroepiploic artery (GEA) graft to the RCA. Coronary angiography revealed total occlusion in proximal LAD, while both graft vessels had good flow. Retrograde percutaneous coronary intervention (PCI) procedure from the septal channel via GEA graft to the RCA was performed for total occlusion of LAD. Despite the tortuous GEA, deep engagement with a 4-french guiding catheter ensured powerful back-up force. After retrograde wire crossing, two drug-eluting stents were implanted, successfully.

Oxygen utilization and the branchial pressure gradient during ram ventilation of the shortfin mako,Isurus oxyrinchus: is lamnid shark–tuna convergence constrained by elasmobranch gill morphology?

Ram ventilation and gill function in a lamnid shark, the shortfin mako, Isurus oxyrinchus, were studied to assess how gill structure may affect the lamnid-tuna convergence for high-performance swimming. Despite differences in mako and tuna gill morphology, mouth gape and basal swimming speeds, measurements of mako O(2) utilization at the gills (53.4±4.2%) and the pressure gradient driving branchial flow (96.8±26.1 Pa at a mean swimming speed of 38.8±5.8 cm s(-1)) are similar to values reported for tunas. Also comparable to tunas are estimates of the velocity (0.22±0.03 cm s(-1)) and residence time (0.79±0.14 s) of water though the interlamellar channels of the mako gill. However, mako and tuna gills differ in the sites of primary branchial resistance. In the mako, approximately 80% of the total branchial resistance resides in the septal channels, structures inherent to the elasmobranch gill that are not present in tunas. The added resistance at this location is compensated by a correspondingly lower resistance at the gill lamellae accomplished through wider interlamellar channels. Although greater interlamellar spacing minimizes branchial resistance, it also limits lamellar number and results in a lower total gill surface area for the mako relative to tunas. The morphology of the elasmobranch gill thus appears to constrain gill area and, consequently, limit mako aerobic performance to less than that of tunas.

Percutaneous coronary intervention for chronic total occlusive lesion of a left anterior descending artery using the retrograde approach via a septal–septal channel

The retrograde approach is an effective therapeutic strategy for chronic total occlusion (CTO) intervention. In CTO cases, the retrograde approach from the opposite coronary artery is not always applicable. In certain left anterior descending (LAD) CTO cases, the distal LAD is filled from the septal channel where it is supplied by the proximal septal route. We report two LAD CTO cases of percutaneous coronary intervention (PCI) conducted with a wire from the proximal septal branch to the distal septal channel using the retrograde approach.

Septal infusions of the hyperpolarization-activated cyclic nucleotide-gated channel (HCN-channel) blocker ZD7288 impair spontaneous alternation but not inhibitory avoidance.

Blockade of septal hyperpolarization-activated cyclic nucleotide-gated channels (HCN) impairs hippocampal theta, an effect that would be expected to impair memory. To test this hypothesis, the present experiments determined whether septal infusions of the selective HCN channel blocker ZD7288 would impair performance on two memory tasks that involve the septo-hippocampal system: spontaneous alternation (SA) and continuous multiple inhibitory avoidance (CMIA). Fifteen minutes prior to assessing SA or CMIA, different groups of male Sprague-Dawley rats were given septal infusions of saline or ZD7288 (0.2, 0.6 or 1.5 microg/0.5 micro1). Septal infusions of ZD7288 impaired SA in a dose-dependent manner; the same infusions did not affect CMIA acquisition or retention. These results appear to be the first demonstration that HCN channels in the medial septum influence memory. Specifically, they suggest that septal HCN channels play a permissive role in spatial working memory, but do not influence emotional long-term memory. Given that these channels are preferentially located on GABA septo-hippocampal projection neurons, the present data provide further evidence that these projection neurons are involved in memory.

Electrical activation of the ventricular myocardium of the crocodile Crocodylus johnstoni: a combined microscopic and electrophysiological study

We mapped the sequence of ventricular depolarization in the crocodile Crocodylus johnstoni. We also attempted to find specialized conduction tissue within the ventricular myocardium. Electrical recordings with miniature multi-point electrodes revealed two strands of rapidly conducting tissue (channels) within the interventricular septum, suggestive of conductive tissue pathways. From these septal channels, wavefronts of excitation swept around each ventricle. Electrical recordings did not indicate that there was conductive tissue in the wall of either ventricle. Similarly, microscopic studies of the septal channels provided no indication of specialized conductive tissue. We suggest that the channels of early septal depolarization provide the crocodile heart with a high speed depolarization pathway functionally analogous to a rudimentary conductive system.