Ablation of Refractory Papillary Muscle Ventricular Tachycardia Warranting Multiple Adjunctive Ablation Techniques: A Combined Approach for Success

A 27-year-old male presented to our institution with recurrent unifocal premature ventricular contraction/nonsustained ventricular tachycardia (VT) with associated cardiomyopathy. The patient had undergone three prior ablation procedures with continued arrhythmia. Mapping led to identification of the VT arising from the basal aspect of the left ventricular anterolateral papillary muscle. Conventional ablation techniques were unsuccessful. We incorporated adjunctive ablation techniques in this case that ultimately led to a successful outcome. The present discussion covers the roles of intracardiac echocardiography, induced apnea, and low-ionic irrigation

Neuronally released vasoactive intestinal polypeptide alters atrial electrophysiological properties and may promote atrial fibrillation

BACKGROUND: Vagal hyperactivity promotes atrial fibrillation (AF), which has been almost exclusively attributed to acetylcholine. Vasoactive intestinal polypeptide (VIP) and acetylcholine are neurotransmitters co-released during vagal stimulation. Exogenous VIP has been shown to promote AF by shortening action potential duration (APD), increasing APD spatial heterogeneity, and causing intra-atrial conduction block. OBJECTIVE: The purpose of this study was to investigate the effects of neuronally released VIP on atrial electrophysiologic properties during vagal stimulation. METHODS: We used a specific VIP antagonist (H9935) to uncover the effects of endogenous VIP released during vagal stimulation in canine hearts. RESULTS: H9935 significantly attenuated (1) the vagally induced shortening of atrial effective refractory period and widening of atrial vulnerability window during stimulation of cervical vagosympathetic trunks (VCNS) and (2) vagal effects on APD during stimulation through fat-pad ganglion plexus (VGPS). Atropine completely abolished these vagal effects during VCNS and VGPS. In contrast, VGPS-induced slowing of local conduction velocity was completely abolished by either VIP antagonist or atropine. In pacing-induced AF during VGPS, maximal dominant frequencies and their spatial gradients were reduced significantly by H9935 and, more pronouncedly, by atropine. Furthermore, VIP release in the atria during vagal stimulation was inhibited by atropine, which may account for the concealment of VIP effects with muscarinic blockade. CONCLUSION: Neuronally released VIP contributes to vagal effects on atrial electrophysiologic properties and affects the pathophysiology of vagally induced AF. Neuronal release of VIP in the atria is inhibited by muscarinic blockade, a novel mechanism by which VIP effects are concealed by atropine during vagal stimulation

Complex Left Atrial Appendage Morphology Is an Independent Risk Factor for Cryptogenic Ischemic Stroke

Importance: Ischemic strokes pose a significant health burden. However, the etiology of between 20 and 40% of these events remains unknown. Left atrial appendage morphology may influence the occurrence of thromboembolic events.Design: A retrospective cross-sectional study was conducted to investigate the role of LAA morphology in patients with atrial fibrillation (AF) and cardioembolic-associated stroke and patients with cryptogenic stroke without atrial fibrillation. LAA morphology is classified into two groups: (1) simple (chicken-wing) vs. (2) complex (non-chicken wing) based on transesophageal echocardiography (TEE) findings. In addition to the LAA morphology, left atrial parameters, including orifice diameter, depth, emptying velocity, and filling velocity, were collected for both groups. Mathematical, computational models were constructed to investigate flow velocities in chicken-wing and non-chicken wing morphological patterns to assess LAA function further.Findings: TEE values for volume, size, emptying, and filling velocities were similar between simple and complex LAA morphology groups. Patients with cryptogenic stroke without coexisting AF were noted to have significantly higher rates of complex LAA morphology. Chicken-wing LAA morphology was associated with four-fold higher flow rate (kg/s) in computational simulations.Conclusions: Complex LAA morphology may be an independent contributing factor for cryptogenic strokes. Further studies are warranted to investigate the mechanism involved in LAA morphology and thromboembolic events

Isolated hemopericardium after initiation of rivaroxaban: Implications and potential mechanisms

Direct oral anticoagulants have become increasingly used for atrial fibrillation and venothromboembolic disease. Thus far, there have been a few published cases of pericardial effusion associated with rivaroxban. However, there has been little published regarding the effects of concurrent medications and their effect on the cytochrome enzyme systems involved in rivaroxaban metabolism. We present a case of a 76-year-old female who develops a spontaneous haemopericardium after initiating rivaroxaban. After thorough medical reconciliation, we offer pharmacokinetic mechanisms that may have contributed to the haemopericardium. This case demonstrates the importance of reviewing patients medication lists and utilizing basic pharmacokinetics to prevent adverse events

Impact of local ablation on interconnected channels within ventricular scar: mechanistic implications for substrate modification.

BACKGROUND: The extent to which channels within scar are interconnected is not known. The objective of the study was to evaluate the impact of local ablation of late potentials (LPs) on adjacent and remote areas of slow conduction with simultaneous multipolar mapping. METHODS AND RESULTS: Analysis was performed on consecutive patients referred for ablation of scar-mediated ventricular tachycardia with double ventricular access. Ablation was performed targeting the earliest of LPs visualized on the multipolar catheter, and the impact on later LPs was recorded. In 21 patients, a multipolar catheter placed within scar visualized spatially distinct LPs. Among 39 radiofrequency applications, ablation at earlier LPs had an effect on neighboring and remote LPs in 31 (80%), with delay in 8 (21%), partial elimination in 9 (23%), and complete elimination in 14 (36%). The mean distance where an ablation impact was detected was 17.6±14.7 mm (range, 2-50 mm). Among all patients, 9.7±7.8 radiofrequency applications were delivered to homogenize the targeted scar region with a mean number of 23±12 LPs targeted. CONCLUSIONS: Ablation can eliminate neighboring and remote areas of slow conduction, suggesting that channels within scar are frequently interconnected. This is the first mechanistic demonstration to show that ablation can modify electrical activity in regions of scar outside of the known radius of an radiofrequency lesion. The targeting of relatively earlier LPs can expedite scar homogenization without the need for extensive ablation of all LPs