1/323. ventricular fibrillation due to long qt syndrome probably caused by clindamycin.Prolongation of QT time interval may be provoked by a limited number of drugs, especially macrolide antibiotics. We describe a case of QT time interval prolongation induced by clindamycin with subsequent repeated ventricular fibrillation and resuscitation; there is no previous report in the literature of QT time prolongation caused by lincosamides.- - - - - - - - - - ranking = 1keywords = long (Clic here for more details about this article) |
2/323. ventricular fibrillation related to reversal of the neuromuscular blockade in a patient with long qt syndrome.The long qt syndrome (LQTS) is associated with syncopal attacks or even sudden death at a young age due to ventricular fibrillation. We report a patient with an undiagnosed LQTS who had an episode of cardiac arrest during the final part of general anesthesia, immediately after the drugs for reversal of the neuromuscular blockade were given. We suggest that the administration of glycopyrronium might have been the provoking factor in this patient.- - - - - - - - - - ranking = 0.71428571428571keywords = long (Clic here for more details about this article) |
3/323. C-terminal HERG mutations: the role of hypokalemia and a KCNQ1-associated mutation in cardiac event occurrence.BACKGROUND: The long-QT syndrome (LQTS) is a genetically heterogeneous disease in which 4 genes encoding ion-channel subunits have been identified. Most of the mutations have been determined in the transmembrane domains of the cardiac potassium channel genes KCNQ1 and HERG. In this study, we investigated the 3' part of HERG for mutations. methods AND RESULTS: New specific primers allowed the amplification of the 3' part of HERG, the identification of 2 missense mutations, S818L and V822 M, in the putative cyclic nucleotide binding domain, and a 1-bp insertion, 3108 1G. hypokalemia was a triggering factor for torsade de pointes in 2 of the probands of these families. Lastly, in a large family, a maternally inherited G to A transition was found in the splicing donor consensus site of HERG, 2592 1G-A, and a paternally inherited mutation, A341E, was identified in KCNQ1. The 2 more severely affected sisters bore both mutations. CONCLUSIONS: The discovery of mutations in the C-terminal part of HERG emphasizes that this region plays a significant role in cardiac repolarization. Clinical data suggests that these mutations may be less malignant than mutations occurring in the pore region, but they can become clinically significant in cases of hypokalemia. The first description of 2 patients with double heterozygosity associated with a dramatic malignant phenotype implies that genetic analysis of severely affected young patients should include an investigation for >1 mutation in the LQT genes.- - - - - - - - - - ranking = 0.14285714285714keywords = long (Clic here for more details about this article) |
4/323. Long-term (subacute) potassium treatment in congenital HERG-related long qt syndrome (LQTS2).INTRODUCTION: Congenital long qt syndrome (LQTS) is subdivided according to the underlying gene defect. In LQTS2, an aberrant HERG gene that encodes the potassium channel IKr leads to insufficient IKr activity and delayed repolarization, causing ECG abnormalities and torsades de pointes (TdP). Increasing serum potassium levels by potassium infusion normalizes the ECG in LQTS2 because IKr activity varies with serum potassium levels. methods AND RESULTS: In an LQTS2 patient who presented with TdP, we attempted to achieve a long-term (subacute) elevation of serum potassium by increased potassium intake and potassium-sparing drugs. However, due to renal potassium homeostasis, it was impossible to achieve a long-lasting rise of serum potassium above 4.0 mmol/L. CONCLUSION: Although raising serum potassium reverses the ECG abnormalities in LQTS2, a long-lasting rise of serum potassium is only partially achievable because in the presence of normal renal function, potassium homeostasis limits the amount of serum potassium increase.- - - - - - - - - - ranking = 1.1428571428571keywords = long (Clic here for more details about this article) |
5/323. Preoperative hypoglycaemia, propranolol and the Jervell and Lange-Nielsen syndrome.The Jervell and Lange-Nielsen syndrome is an autosomal recessive trait characterized by deafness and electrocardiographic changes. These changes include prolongation of the QT interval and T-wave inversion. Treatment may include the use of beta-blockers to prevent the development of malignant ventricular arrhythmias and sudden death. We report a patient with this syndrome, who was receiving propranolol orally and who became hypoglycaemic during the preoperative fasting period prior to cochlear implantation.- - - - - - - - - - ranking = 0.14285714285714keywords = long (Clic here for more details about this article) |
6/323. A de novo missense mutation (R1623Q) of the SCN5A gene in a Japanese girl with sporadic long QT sydrome. Mutations in brief no. 140. Online.Two missense mutations and a nine-nucleotide deletion of the cardiac sodium channel (SCN5A) gene have been shown to cause long qt syndrome (LQTS) in several familial cases. We identified a novel missense mutation (R1623Q) of the SCN5A gene in a Japanese girl with sporadic LQTS. We used polymerase chain reaction, single-strand conformation polymorphism analysis and dna sequence analysis to identify a mutation of the SCN5A gene in the patient. A single nucleotide substitution of guanine to adenine, in codon 1612, changed the coding sense of the SCN5A from arginine to glutamine (R1623Q) in the S4 segment of domain IV which is a highly conserved region of the SCN5A. This mutation was not identified in the unaffected biological parents and brother of the patient, and 100 normal, unrelated individuals. This finding is the first evidence of a de nova mutation in SCN5A associated with LQTS.- - - - - - - - - - ranking = 0.71428571428571keywords = long (Clic here for more details about this article) |
7/323. prenatal diagnosis of long qt syndrome using fetal magnetocardiography.We describe the detection of congenital long qt syndrome in a fetus at 37 weeks' gestation using magnetocardiography (MCG). The prenatal diagnosis was confirmed by standard electrocardiography (ECG) performed after birth. This is the first case report of fetal long qt syndrome detected by MCG. Fetal MCG may be useful in the prenatal diagnosis of congenital cardiac disease with abnormal ECG findings.- - - - - - - - - - ranking = 0.85714285714286keywords = long (Clic here for more details about this article) |
8/323. A variant of long qt syndrome manifested as fetal tachycardia and associated with ventricular septal defect.Two patients with a novel variant of long qt syndrome are described. The clinical course was characterised by an in utero onset of ventricular tachycardia and atrioventricular block (at 26 and 30 weeks' gestational age, respectively), and an association with a ventricular septal defect. Studies of both patients' families identified relatives with prolonged QT interval, syncope, or sudden death. One patient died of intractable ventricular tachycardia at 4 days old. The other received beta blocker treatment and a pacemaker. She died suddenly at the age of 10 months. The unique association with ventricular septal defect and the malignant clinical course warrants further molecular diagnosis of this novel variant of long qt syndrome.- - - - - - - - - - ranking = 1keywords = long (Clic here for more details about this article) |
9/323. Prominent bifid T waves observed in the QT prolongation caused by complete atrioventricular blockade in a hypokalemic diabetic patient.A 63-year-old diabetic man was admitted with general fatigue. Electrocardiogram (ECG) on admission showed complete atrioventricular (AV) blockade associated with prominent bifid T waves. The second component of the bifid T waves was distinguished from U waves by the beat-to-beat varying bifidity and the nadir between the two components located at > or = 1 mm above the isoelectric line. Range of absolute QT interval was 535 to 650 ms. hypokalemia (3.6 mEq/L) was noted at admission. Partial restoration of the potassium level (3.9 mEq/L) prior to temporary ventricular demand pacing obscured the bifid T waves and attenuated the QT prolongation and dispersion to some extent (absolute QT interval ranging 520 to 620 ms). It was concluded that marked bradycardia caused by complete AV blockade (ie, a junctional escaped rhythm at a rate of 42 beats/min), hypokalemia, and underlying diabetes mellitus contributed in concert to the QT prolongation and dispersion leading to the prominent bifid T waves.- - - - - - - - - - ranking = 0.85714285714286keywords = long (Clic here for more details about this article) |
10/323. Splicing mutations in KCNQ1: a mutation hot spot at codon 344 that produces in frame transcripts.BACKGROUND: Long-QT syndrome is a monogenic disorder that produces cardiac arrhythmias and can lead to sudden death. At least 5 loci and 4 known genes exist in which mutations have been shown to be responsible for the disease. The potassium channel gene KCNQ1, previously named KVLQT1, on chromosome 11p15.5 is one of these. methods AND RESULTS: We initially analyzed one family using microsatellite markers and found linkage to KCNQ1. mutation detection showed a G to C change in the last base of exon 6 (1032 G-->C) that does not alter the coded alanine. Restriction digest analysis in the family showed that only affected individuals carried the mutation. A previous report suggested that a G to A substitution at the same position may act as a splice mutation in KCNQ1, but no data was given to support this hypothesis nor was the transcription product identified. We have shown by reverse-transcription polymerase chain reaction that 2 smaller bands were produced for the KCNQ1 gene transcripts in addition to the normal-sized transcripts when lymphocytes of affected individuals were analyzed. Sequencing these transcripts showed a loss of exon 7 in one and exons 6 and 7 in the other, but an in-frame transcript was left in each instance. We examined other families in whom long-QT syndrome was diagnosed and found another unreported splice-site mutation, 922-1 G-->C, in the acceptor site of intron 5, and 2 of the previously reported 1032 G-->A mutations. All these showed a loss of exons 6 and 7 in the mutant transcripts, validating the proposal that a consensus sequence is affected in the exonic mutations and that the integrity of the base at position 1032 is essential for correct processing of the transcript. CONCLUSIONS: The 6 cases already reported in the literature with the 1032 G-->A transition, the novel 1032 G-->C transversion, and a recent G-->T transversion at the same base show that codon 344 is the second most frequently mutated after codon 341, suggesting at least two hotspots for mutations in KCNQ1.- - - - - - - - - - ranking = 0.14285714285714keywords = long (Clic here for more details about this article) |
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