Sanjeev Goyal

Mutation in the S3 segment of KCNQ1 results in familial lone atrial fibrillation.

BACKGROUND Mutations in several ion channel genes have been reported to cause rare cases of familial atrial fibrillation (AF). OBJECTIVE The purpose of this study was to determine the genetic basis for AF in a family with autosomal dominant AF. METHODS Family members were evaluated by 12-lead ECG, echocardiogram, signal-averaged P-wave analysis, and laboratory studies. Fourteen family members in AF-324 were studied. Six individuals had AF, with a mean age at onset of 32 years (range 16-59 years). RESULTS Compared with unaffected family members, those with AF had a longer mean QRS duration (100 vs 86 ms, P = .015) but no difference in the corrected QT interval (423 +/- 15 ms vs 421 +/- 21 ms). The known loci for AF and other cardiovascular diseases were evaluated. Evidence of linkage was obtained with marker D11S4088 located within KCNQ1, and a highly conserved serine in the third transmembrane region was found to be mutated to a proline (S209P). Compared to the wild-type channel, the S209P mutant activates more rapidly, deactivates more slowly, and has a hyperpolarizing shift in the voltage activation curve. A fraction of the mutant channels are constitutively open at all voltages, resulting in a net increase in I(Ks) current. CONCLUSION We identified a family with lone AF due to a mutation in the highly conserved S3 domain of KCNQ1, a region of the channel not previously implicated in the pathogenesis of AF.

Inappropriate ICD Therapy Due to Proarrhythmic ICD Shocks and Hyperpolarization

A 50‐year‐old man with an ischemic cardiomyopathy underwent ICD implantation for inducible ventricular fibrillation (VF). Sixteen months later he experienced inappropriate ICD therapy due to atrial fibrillation with a rapid ventricular response. The initial shock resulted in the initiation of VF (proarrhythmia) and the patient received an additional shock converting his rhythm to an idioventricular rhythm with a cycle length of 490 ms (122 beats/min). Due to lead hyperpolarization, the device oversensed ventricular events and the patient subsequently received additional shocks. (PACE 2004; 27:415–416)

Persistent Left Superior Vena Cava-Inferior Vena Caval Communication Complicating Implantation of an Implantable Cardioverter Defibrillator

A persistent left superior vena cava has been observed in 0.3% of the general population on autopsy. Its presence can complicate left‐sided device implantation. Commonly, a LSVC connects to the right atrium via the coronary sinus. A LSVC‐accessory hemiazygous‐hemiazygous‐inferior vena caval communication has not been described previously. The presence of such a congenital venous anomaly will prohibit a left‐sided device implant.

Cardiac Sarcoidosis With Primary Involvement of the Tricuspid Valve

Sarcoid granulomas usually involve the myocardium with rare focal extensions into the pericardium and endocardium with resultant conduction defects, ventricular arrhythmias, and ventricular systolic and diastolic dysfunction. Primary involvement of valvular leaflets resulting in valvular regurgitation or stenosis is not known. We present a case of a wastewater consultant who developed tricuspid regurgitation and symptomatic atrioventricular block secondary to infiltration of tricuspid leaflets and conduction system from sarcoid granulomas. The patient later developed severe dilated cardiomyopathy as a result of extensive cardiac sarcoidosis necessitating cardiac transplantation. Valvular regurgitation should be included as one of the presenting manifestations of cardiac sarcoidosis.

Cytomegalovirus infection in AIDS presenting as a rectal mass

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Mouse Heart Rate in a Human: Diagnostic Mystery of an Extreme Tachyarrhythmia

We report telemetry recording of an extreme non-fatal tachyarrhythmia noted in a hospitalized quadriplegic male with history of atrial fibrillation where the average ventricular conduction rate was found to be about 600 beats per minute and was associated with transient syncope. A medical literature review suggests that the fastest human ventricular conduction rate reported to date in a tachyarrhythmia is 480 beats per minute. We therefore report the fastest human heart rate noted in a tachyarrhythmia and the most probable mechanism of this arrhythmia being a rapid atrial fibrillation with 1:1 conduction in the setting of probable co-existing multiple bypass tracts.

Book Review: Book Review: Peter Kohl, Frederick Sachs, and Michael Franz Cardiac Mechano-Electric Feedback and Arrhythmias: From Pipette to Patient St Louis, MO: Elsevier Saunders, 2005. 423 pp. ISBN: 1-4160-0034-8

We are just beginning to understand the mechanism of common cardiac arrhythmias such as atrial fibrillation and ventricular fibrillation. This book by Dr Kohl et al attempts to describe the factors responsible for the genesis of cardiac arrhythmias and cardiomyopathies with special emphasis on mechanoelectric coupling or feedback which is thought to play a role in both electrical and mechanical remodeling. There is appropriate importance given to atrial fibrillation and the role of mechanical stretch in the genesis of cardiac arrhythmias throughout the book. Most of the figures in the book are complex and unfortunately may be difficult to understand for a clinician. This book, however, can be a great reference text on mechano-electrical feedback. The chapter on the role of the pericardium on mechanical modulation of cardiac function was particularly interesting because not many clinicians are aware of the role of the pericardium in heart failure. Although the authors have written an entire chapter on the mechanisms and efficacy of the precordial thump and its antiarrhythmic effects, it is no longer recommended by the American Heart Association (AHS) Advanced Cardiac Life Support (ACLS) guidelines and clinical data have questioned its efficacy in restoring sinus rhythm. The chapters on cardiac assist devices and cardiac resynchronization therapy were very well written and are clinically applicable. An unusual aspect of the book was that there was no table of contents, which would have been helpful. In summary, it is a great reference book on mechano-electrical feedback, and I recommend it highly for the researchoriented cardiac electrophysiologist. Journal of Intensive Care Medicine 25(4) 243 a 2010 SAGE Publications Reprints and permission: sagepub.com/journalsPermissions.nav http://jicm.sagepub.com