Evidence for concealed fasciculo-ventricular connections as revealed by His bundle pacing.

BACKGROUND: It is almost 100 years ago since Mahaim described the so-called paraspecific connections between the ventricular conduction axis and the crest of the muscular ventricular septum, believing such pathways to be ubiquitous. These pathways, however, have yet to be considered as potential pathways for septal activation during His bundle pacing. MATERIALS: So as to explore the hypothesis that specialised septal pathways might provide the substrate for septal activation during His bundle pacing, we compared the findings from 22 serially sectioned histological datasets and 34 different individuals undergoing His bundle pacing. RESULTS: We found histologically specialised pathways connecting the branching component of the atrioventricular conduction axis with the crest of the muscular ventricular septum in almost four-fifths of the histological datasets. In 32 of 34 patients undergoing His bundle pacing, the QRS complex closely resembled published images of known conduction through fasciculo-ventricular pathways. In only two patients was a delta wave not seen at any pacing voltages. Capture of these connections varied according to pacing voltage, a finding which correlated with the distance of the pathways from the site of penetration of the ventricular conduction axis. Ventricular activation times remained normal in the presence of the delta wave at higher pacing voltage but were prolonged at lower voltages. CONCLUSIONS: Our histologic findings confirm fasciculo-ventricular connections, initially described by Mahaim as being paraspecific, are likely ubiquitous. Analysis of 12-lead electrocardiograms leads us to conclude that fasciculo-ventricular pathways, concealed during sinus rhythm, become manifest with His bundle pacing.

Rivaroxaban as Therapy for Saphenous Venous Graft Failure due to Venous Outflow Mismatch.

Background: Recurrent angina and long-term occlusion following coronary artery bypass graft surgery is often treated with percutaneous coronary intervention, a high-risk intervention for distal embolization. Here, we present the utilization of the novel oral anticoagulant, rivaroxaban, in the treatment of saphenous vein graft thrombosis with complete resolution of the thrombus secondary to graft outflow mismatch. Case Presentation. A 69-year-old man with triple coronary artery bypass grafting using a saphenous vein and left internal mammary artery, performed in 2017, presented at our hospital for recurrent angina. Coronary angiography revealed a patent LIMA to LAD and a large clot burden in the venous conduit to the first OM/terminal circumflex-theorized to be due to an outflow mismatch of the large saphenous vein to the native artery resulting in stasis. Instead of percutaneous coronary intervention, he was treated with rivaroxaban 20 mg once a day. The angiography 4 weeks after starting rivaroxaban showed complete resolution of the thrombus. Conclusion: Rivaroxaban could become a potential treatment option in thrombus reversal due to static venous flow with subsequent long-term patency of the graft. Additionally, its use may be indicated in the generalized prevention of VGF.