Layered activation of epicardial scar in arrhythmogenic right ventricular dysplasia: possible substrate for confined epicardial circuits.

Background: Ventricular tachycardia ablation in arrhythmogenic right ventricular dysplasia (ARVD) is more successful when including epicardial ablation. Scarring may cause independent, layered epicardial activation and promote epicardially confined ventricular tachycardia circuits. We aimed to characterize transmural right ventricular activation in ARVD patients and to compare this with reference patients without structural heart disease.

Allergic reaction to suture material after an ICD procedure: device infection mimicry.

When an implanted device is infected, complete explantation of the device system, including lead extraction, is usually required. Superficial problems with wound healing may be managed more conservatively, but distinguishing between a surface process and deeper infection can pose a clinical challenge. We present a case of poor wound healing after an ICD pocket revision procedure, and an allergic reaction to the suture material was found to be the cause.

Mechanism of complex fractionated electrograms recorded during atrial fibrillation in a canine model.

Background: Complex fractionated atrial electrograms (CFEs) have been described as a target during atrial fibrillation (AF) ablation; however, the mechanism leading to CFEs is poorly understood. We used noncontact mapping in a canine model of AF to determine the activation patterns in areas of CFEs.

Methods: Sustained AF was induced in 10 canines with 10-12 weeks of atrial tachy-pacing at 440 ppm.

Noncontact electroanatomic mapping to characterize typical atrial flutter: participation of right atrial posterior wall in the reentrant circuit.

Background: Reentry utilizing cavotricuspid isthmus (CTI) is accepted as the mechanism underlying typical atrial flutter (AFLT). However, it is unclear how the right atrial (RA) posterior wall (PW) participates in AFLT circuit. We sought to investigate this by using noncontact electroanatomic mapping.

High-density biatrial pacing protects against atrial fibrillation by synchronizing left atrial tissue.

Purpose: The induction and sustainability of atrial fibrillation (AF) are most commonly due to pulmonary vein (PV) triggers and left atrial (LA) substrate. We hypothesized that simultaneous pacing of the PV ostia, LA, and right atrium (RA) reduces AF susceptibility by synchronizing atrial activity.

Methods: Mongrel dogs were rapidly paced and maintained in AF for 3 months before cardioversion.

Dominant frequency mapping of atrial fibrillation: comparison of contact and noncontact approaches.

Introduction: The ability to acquire a dominant frequency (DF) map during atrial fibrillation (AF) instantaneously using noncontact mapping has significant advantages over the current sequential contact mapping approach; however, the relationship between DFs determined from contact bipolar and noncontact unipolar recordings is unknown. We sought to determine the difference between DFs determined using contact bipolar, contact unipolar, noncontact unipolar, and noncontact pseudobipolar recordings.

Methods: Sustained AF was induced in 5 canines with 10 weeks of atrial tachy-pacing at 440 ppm.

Biatrial primary synovial sarcoma of the heart.

Synovial sarcomas that primarily arise from the heart and pericardium are extremely rare, especially the ones involving both sides of the heart. To date, few cases have been reviewed in the literature. Our patient was a 36-year-old man who presented with primary biatrial synovial sarcoma that also involved the tricuspid annulus, heart valves, and interatrial septum.

Thrombotic "ghosts": echocardiographic appearance of thrombi with hollow cores and implications regarding mechanism of spontaneous clot lysis.

We present a case of a patient whose transesophageal echocardiogram revealed multiple thrombi in different stages of central lysis. This produced the appearance of undulating thin outer shells and lucent central cores resembling "ghosts." Although most thrombi appear to resolve by a lytic process that produces reduction in size from the exterior surface inward, the thrombi illustrated in this case appear to lyse from the interior outward.