Spectrum of atrial arrhythmias using the ligament of Marshall in patients with atrial fibrillation.

BACKGROUND: The role of the ligament of Marshall (LOM) in patients with atrial fibrillation (AF) has not been well defined. OBJECTIVE: The purpose of this study was to describe the role of the LOM in patients with AF and related arrhythmias. METHODS: Fifty-six patients (mean age 63 ± 11 years; persistent AF in 48 [86%]; ejection fraction 0.49 ± 0.13; left atrial diameter 4.7 ± 0.6 cm) with LOM-mediated arrhythmias were included. RESULTS: A LOM-pulmonary vein (PV) connection was present in 18 patients (32%) and was eliminated with radiofrequency (RF) ablation at the left lateral ridge or crux (n = 12), at the mitral annulus (n = 3), or with alcohol/ethanol (EtOH) ablation of the vein of Marshall (VOM; n = 3). A LOM-mediated atrial tachycardia (AT) was present in 13 patients (23%). Thirty-one patients with refractory mitral isthmus conduction were referred for potential EtOH ablation. In the 6 patients in whom VOM was injected during perimitral reentry, EtOH resulted in slowing in 3 patients and termination in 1 patient. In others, EtOH infusion resulted in complete isolation of the left-sided PVs and left atrial appendage. Repeat RF and adjunctive EtOH ablation of the VOM tended to be more effective in creating conduction block across the mitral isthmus than RF ablation alone (P = .057). CONCLUSION: The LOM is responsible for a variety of arrhythmia mechanisms in patients with AF and atrial tachycardia. It may be ablated at any point along its course, at the mitral annulus, at the lateral ridge/PV antrum, and epicardially in the coronary sinus and the VOM itself. EtOH ablation of the VOM may be an adjunctive strategy in patients with refractory perimitral reentry.

M-118, a novel, low-molecular-weight heparin for the potential treatment of cardiovascular disorders.

Safe inhibition of thrombosis is a key therapeutic strategy in modern cardiovascular medicine, and both unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) are commonly used in clinical practice. However, both have several drawbacks, such as the unpredictable pharmacokinetics of UFH and the non-reversibility of LMWH. M-118, being developed by Momenta Pharmaceuticals Inc, is a novel LMWH that has been engineered to overcome the drawbacks of UFH and currently available LMWHs, while maintaining their beneficial attributes. In preclinical studies and phase I clinical trials, M-118 demonstrated potent activity against thrombin and Factor Xa, which could be reversed with protamine; M-118 also demonstrated a high and predictable bioavailability, and a short half-life. Promising results were observed in a phase II clinical trial in patients undergoing coronary interventions, although phase III clinical trials are required to establish the role for M-118 in contemporary medicine.