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Idiopathic Ventricular Fibrillation (idiopathic + ventricular_fibrillation)

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Medical Sciences	100%

Selected Abstracts

Repolarization Abnormality in Idiopathic Ventricular Fibrillation:

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 1 2004
Assessment Using 24-Hour QT-RR, QaT-RR Relationships
Introduction: We evaluated the characteristics of QT-RR and QaT (apex of T wave)-RR relationships in patients with idiopathic ventricular fibrillation (IVF) compared with control subjects. We hypothesized that IVF patients have unique repolarization dynamics related to a reduced fast Na current and a prominent transient outward current. Methods and Results: The study group consisted of 9 men (age 47 ± 10 years) with IVF (6 with Brugada type and 3 with non-Brugada type) who had experienced nocturnal episodes of VF. The control group consisted of 28 healthy age-matched men (age 44 ± 12 years). The relationships between QT and RR intervals and between QaT and RR intervals were analyzed from 24-hour Holter ECG data using an automatic measurement system. Both QT and QaT at RR intervals of 0.6, 1.0, and 1.2 seconds were determined from QT-RR and QaT-RR linear regression lines. Both QT-RR and QaT-RR slopes were lower in the IVF group than in the control group (QT-RR: 0.092 ± 0.023 vs 0.137 ± 0.031, P < 0.001; QaT-RR: 0.109 ± 0.025 vs 0.153 ± 0.028, P < 0.001). QT at an RR interval of 0.6 second did not differ between two groups, but QT at RR intervals of either 1.0 or 1.2 seconds was significantly shorter in the IVF group than in the control group (RR 1.0 s: 0.384 ± 0.018 vs 0.399 ± 0.017, P < 0.05; RR 1.2 s: 0.402 ± 0.019 vs 0.426 ± 0.020, P < 0.01). QaT at RR intervals of either 1.0 or 1.2 seconds also was shorter in the IVF group (RR 1.0 s: 0.289 ± 0.022 vs 0.312 ± 0.021, P < 0.01; RR 1.2 s: 0.311 ± 0.024 vs 0.343 ± 0.024, P < 0.01). In four patients, oral administration of disopyramide (300 mg/day) was effective in suppressing VF episodes and increased slopes of QT-RR and QaT-RR relationships. Conclusion: IVF patients had lower slopes of QT-RR and QaT-RR regression lines and impaired prolongation of QT and QaT at longer RR intervals compared with control subjects. These unique repolarization dynamics may be related to the frequent occurrence of VF episodes at night. (J Cardiovasc Electrophysiol, Vol. 15, pp. 59-63, January 2004) [source]

Risk Stratification of Individuals with the Brugada Electrocardiogram: A Meta-Analysis

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2006
ANIL K. GEHI M.D.
Objectives: We performed a meta-analysis of prognostic studies of patients with a Brugada ECG to assess predictors of events. Background: The Brugada syndrome is an increasingly recognized cause of idiopathic ventricular fibrillation; however, there is wide variation in the prognosis of patients with the Brugada ECG. Methods and Results: We retrieved 30 prospective studies of patients with the Brugada ECG, accumulating data on 1,545 patients. Summary estimates of the relative risk (RR) of events (sudden cardiac death [SCD], syncope, or internal defibrillator shock) for a variety of potential predictors were made using a random-effects model. The overall event rate at an average of 32 months follow-up was 10.0% (95% CI 8.5%, 11.5%). The RR of an event was increased (P < 0.001) among patients with a history of syncope or SCD (RR 3.24 [95% CI 2.13, 4.93]), men compared with women (RR 3.47 [95% CI 1.58, 7.63]), and patients with a spontaneous compared with sodium-channel blocker induced Type I Brugada ECG (RR 4.65 [95% CI 2.25, 9.58]). The RR of events was not significantly increased in patients with a family history of SCD (P = 0.97) or a mutation of the SCN5A gene (P = 0.18). The RR of events was also not significantly increased in patients inducible compared with noninducible by electrophysiologic study (EPS) (RR 1.88 [95% CI 0.62, 5.73], P = 0.27); however, there was significant heterogeneity of the studies included. Conclusions: Our findings suggest that a history of syncope or SCD, the presence of a spontaneous Type I Brugada ECG, and male gender predict a more malignant natural history. Our findings do not support the use of a family history of SCD, the presence of an SCN5A gene mutation, or EPS to guide the management of patients with a Brugada ECG. [source]

Repolarization Abnormality in Idiopathic Ventricular Fibrillation:

Occurrence of "J Waves" in 12-Lead ECG as a Marker of Acute Ischemia and Their Cellular Basis

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 6 2007
SHINDE RITUPARNA M.D.
The "J wave" (also referred to as "the Osborn wave,""the J deflection," or "the camel's hump") is a distinctive deflection occurring at the QRS-ST junction. In 1953, Dr. John Osborn described the "J wave" as an "injury current" resulting in ventricular fibrillation during experimental hypothermia. Although "J Wave" is supposed to be pathognomonic of hypothermia, it is seen in a host of other conditions such as hypercalcemia, brain injury, subarachnoid hemorrhage, cardiopulmonary arrest from over sedation, the Brugada syndrome, vasospastic angina, and idiopathic ventricular fibrillation. However, there is paucity of literature data as regards to ischemic etiology of "J Wave." In this article, we present a case where "J waves" were probably induced by ischemia. We also discuss the mechanism of ischemia-induced "J wave" accentuation and its prognostic implications. [source]