DRESS syndrome-associated acute necrotizing eosinophilic myocarditis with giant cells.

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is an uncommon drug hypersensitivity reaction caused by a wide variety of agents. It has a characteristic latent period between 2 and 8 weeks from the onset of drug ingestion followed by a slow resolution with the potential for relapse. Despite being a potentially fatal disease, little is understood about its variable clinical presentation and why it can present long after removal of the offending drug. Visceral organ involvement typically occurs, but rarely results in clinically manifested cardiac injury. In its most aggressive form, acute necrotizing eosinophilic myocarditis (ANEM) can present with DRESS. We present an unusual case of DRESS syndrome due to lamotrigine with confirmed ANEM showing both eosinophils and rare giant cell infiltrates on endomyocardial biopsy. Although lamotrigine has been reported to cause DRESS, it has not been previously implicated as a cause of ANEM.

Bachmann's bundle and coronary sinus ostial pacing accentuate left atrial electrical dyssynchrony in an acute canine model.

INTRODUCTION: In patients with intraatrial conduction delay and sinus node (SN) dysfunction, pacing Bachmann's bundle (BBR) and coronary sinus ostium (CSO) has been suggested to achieve atrial resynchronization with potential beneficial impact on atrial fibrillation and diastolic heart failure. Clinical studies have not shown superiority of one approach. METHODS AND RESULTS: We studied electrical activation sequence in an open-chest acute canine model of normal atrial function in 8 mongrel dogs under general anesthesia. Bipolar plunge electrodes were distributed over the surface of the atria during unifocal pacing, and intracardiac activation sequence was observed. SN pacing resulted in near-simultaneous activation at midline sites (BBR and CSO); the left atrium (LA) was activated by anterior and posterior wavefronts simultaneously propagating septally to laterally and meeting at the low-lateral perimitral LA. Right atrial appendage (RAA) pacing created intra-RA conduction delay and delayed onset of LA activation. Pacing from RAA, CSO, and BBR resulted in nonsimultaneous activation at midline sites and produced an anteroposterior gradient of LA activation. This phenomenon was seen to the greatest degree with midline pacing and shifted the site of latest activation away from the low-lateral perimitral LA in all pacing configurations except SN pacing. CONCLUSION: Pacing-induced intra-LA activation dispersion is enhanced with midline atrial pacing, and secondarily shifts the site of latest activation away from the lateral mitral annulus. Measuring atrial activation times to the low-lateral perimitral LA can underestimate the degree of atrial dyssynchrony and be misinterpreted as atrial synchrony. Establishing clinical impact requires evaluation of human data.

Polymorphic ventricular tachycardia--part II: the channelopathies.

In this article, we explore the clinical and cellular phenomena of primary electrical diseases of the heart, that is, conditions purely related to ion channel dysfunction and not structural heart disease or reversible acquired causes. This growing classification of conditions, once considered together as "idiopathic ventricular fibrillation," continues to evolve and segregate into diseases that are phenotypically, molecularly, and genetically unique.

Polymorphic ventricular tachycardia-part I: structural heart disease and acquired causes.

Polymorphic ventricular tachycardia (PMVT) is an unusual ventricular tachyarrhythmia. Perhaps its most unique characteristic is a continuously evolving QRS morphology. Although the most common substrate for PMVT is structural heart disease, the prevalence of sudden cardiac death in the population without structural heart disease is even greater, and the absence of a myocardial substrate would suggest that PMVT is the anticipated cause of sudden cardiac death in this population as well. Mechanistically, PMVT is distinct from ventricular fibrillation. It appears to be a condition of abnormal repolarization and resultant cellular heterogeneities, and the principles of triggering and reentry have been demonstrated to govern its initiation and maintenance. The "channelopathies"-a growing category of inherited or acquired conditions that predispose to PMVT and sudden cardiac death-present a fascinating challenge with potentially dire consequences as there are few indicators of their existence except for subtle, if any, electrocardiographic changes. The ever-expanding number of pharmaceuticals that affect ion channel function further magnifies this risk.