1/85. 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 = syncope (Clic here for more details about this article) |
2/85. Congenital long-QT syndrome: a case report illustrating diagnostic pitfalls.This article reviews the clinical course of a 10-year-old child with a lifelong history of seizures and congenital deafness who presented after an episode of sudden cardiac arrest secondary to long-QT syndrome-induced torsade de pointes. Jervell-Lange-Nielsen syndrome is a rare cardioauditory syndrome in which affected subjects are susceptible to recurrent syncope and sudden death from ventricular dysrhythmias, usually before the second decade of life. Careful evaluation of suspected subjects is important because of the variability of the QTc interval. Recent research has identified specific gene sequences that encode ion channels responsible for both prolonged QTc interval and deafness. Treatment of symptomatic cardiac disease with beta-blockers in combination with pacemakers and automated internal cardioverter defibrillators can markedly improve quality of life and suppress ventricular dysrhythmias even in the most severely affected subjects. The recent identification of gene sequences identifying some congenital long-QT syndromes may improve screening methods for affected patients and lead to potential therapeutic intervention.- - - - - - - - - - ranking = 1keywords = syncope (Clic here for more details about this article) |
3/85. Corrected QT interval (QTc) prolongation and syncope associated with pseudohypoparathyroidism and hypocalcemia.An adolescent presented with exercise-associated syncope and electrocardiographic corrected QT interval (QTc) prolongation. pseudohypoparathyroidism-induced hypocalcemia was diagnosed. The QTc (485 to 505 milliseconds) shortened during normalization of calcium levels, and syncope has not reoccurred.- - - - - - - - - - ranking = 6keywords = syncope (Clic here for more details about this article) |
4/85. long qt syndrome with a high mortality rate caused by a novel G572R missense mutation in KCNH2.In a four-generation family with long qt syndrome, syncopes and torsades de pointes ventricular tachycardia (TdP) were elicited by abrupt awakening in the early morning hours. The syndrome was associated with a novel KCNH2 missense mutation, G572R, causing the substitution of a glycine residue at position 572, at the end of the S5 transmembrane segment of the HERG K( )-channel, with an arginine residue. This segment is involved in the channel pore and the mutation may cause a reduction in the rapidly activating delayed rectifier K current (Ikr), or changed gating properties of the ion channel, leading to prolonged cardiac repolarization. The electrocardiograms of affected persons showed prolonged QT interval and notched T waves. Despite treatment with atenolol, 200 mg twice daily, the proband still experienced TdP episodes. Three untreated relatives of the proband died suddenly, and unexpectedly, at 18, 32, and 57 years of age. The G572R mutation is thus associated with a high mortality rate, and the clinical presentation illustrates that some mutations may not be controllable by just beta-blockade.- - - - - - - - - - ranking = 1keywords = syncope (Clic here for more details about this article) |
5/85. A novel mutation in KVLQT1, L122P, found in a family with autosomal dominant long qt syndrome.BACKGROUND: Linkage and mutation analysis in long qt syndrome kindreds has demonstrated locus heterogeneity, with causative mutations reported in at least 5 different genes, including KVLQT1. methods AND RESULTS: A 12-year-old male proband with recurrent syncope and a prolonged QT interval underwent clinical assessment and exercise testing along with 3 affected and 3 unaffected family members. The coding regions of 5 putative transmembrane segments (S2-S6) and a putative pore region of the KVLQT1 gene for the proband were amplified with the polymerase chain reaction. dna sequencing of the KVLQT1 gene of the proband revealed a T-->C transversion at the second position of codon 122, which predicted a substitution of proline for leucine (L122P). By using restriction analysis, the L122P was found to be co-segregated with the electrocardiographic abnormalities in the nuclear family. Although the patient's mother was heterozygous for L122P, neither maternal grandparent was a carrier, suggesting that the mutation arose spontaneously. In comparison, there was a complete absence of the mutation in 1336 alleles from 668 normal individuals of 6 different ethnic backgrounds. CONCLUSION: The KVLQT1 L122P mutation is a rare novel mutation that probably arose spontaneously in this family, leading to long QT syndrome.- - - - - - - - - - ranking = 1keywords = syncope (Clic here for more details about this article) |
6/85. Control of idiopathic ventricular fibrillation by implantable cardioverter-defibrillator in a child who survived sudden death.Idiopathic ventricular fibrillation (VF) is extremely rare in children who have not previously undergone cardiac surgery. patients resuscitated from idiopathic VF remain at risk for recurrence. The use of an implantable cardioverter-defibrillator (ICD) effectively prevents such recurrences. We report the case of a 12-year-old girl who had a history of recurrent syncope and had survived an episode of VF. Serial studies after prolonged but successful resuscitation, including echocardiography, an electrocardiogram (ECG), and coronary angiography failed to reveal abnormal cardiac structures responsible for VF. No abnormal conduction pathways or abnormal early or late after depolarization were found on electrophysiologic study. The ST segments of the 12-lead ECG remained normal after procainamide challenge. The patient underwent ICD implantation 2 weeks after admission and syncope did not recur during a follow-up of 14 months. This report emphasizes that idiopathic VF may be responsible for syncope in children. ICD therapy prevents the recurrence of idiopathic VF and the associated risk of sudden death.- - - - - - - - - - ranking = 3keywords = syncope (Clic here for more details about this article) |
7/85. Familial hypertrophic cardiomyopathy associated with prolongation of the QT interval.In a 61 year old female patient who suffered from atypical chest pain we diagnosed long qt syndrome by QTc duration of 467 ms, macroscopic T wave alternans and notched T waves in three leads and hypertrophic cardiomyopathy with asymmetric thickening of basal parts of the septum (2.0 cm) without relevant outflow tract obstruction by echocardiography. coronary angiography could exclude coronary artery disease. In a systematic family screening two sons of the patient could also be diagnosed as having long qt syndrome with QTc durations of 472 and 496 ms and asymmetric septal thickening (1.8 and 2.1 cm, respectively). One of these two sons suffered from pre-syncope, the other was asymptomatic despite maximum sports activity. In the third son, LQTS and hypertrophic cardiomyopathy could be excluded.- - - - - - - - - - ranking = 1keywords = syncope (Clic here for more details about this article) |
8/85. Identical twins with long qt syndrome associated with a missense mutation in the S4 region of the HERG.Familial long qt syndrome (LQTS) is caused by mutations in genes encoding ion channels important in determining ventricular repolarization. Mutations in at least five genes have been associated with the LQTS. Fire genes, KCNQ1, HERG, SCN5A, KCNE1, and KCNE2, have been identified. We have identified a missense mutation in the HERG gene in identical twins in a Japanese family with LQTS. The identical twins in our study had QT prolongation and the same missense mutation. However only the proband had a history of syncope. Although many mutations in LQT genes have been reported, there are few reports of twins with LQTS. This is the first report, to our knowledge, of identical twins with a HERG gene mutation.- - - - - - - - - - ranking = 1keywords = syncope (Clic here for more details about this article) |
9/85. bradycardia-induced long qt syndrome caused by a de novo missense mutation in the S2-S3 inner loop of HERG.long qt syndrome is a congenital disorder that presents with a defective cardiac ion channel and is either associated with prolonged action potential or, more commonly, known as an acquired form in which "torsades de pointes" type arrhythmias specifically occur after secondary causes. We report a case of a novel HERG mutation (A490T) that caused a bradycardia-associated form of long QT syndrome. A 27-year-old woman exhibited recurrent syncope due to torsades de pointes associated with a disturbance of the cardiac conduction system. By using polymerase chain reaction and single strand conformational polymorphism analyses, we identified a heterozygous single nucleotide substitution of HERG (G to A at nt 1468). This mutational change was not present in 140 Japanese control individuals. Electrophysiological assays for the A490T mutant HERG channel were conducted in the heterologous expression system with COS7 cells. The mutant channel was found to reconstitute functional channel currents, suggesting the homomeric mutant channel was functional. The mutation did not change the properties of the activation gate and inward rectification, however the current density of this mutant channel was small compared with that of wild type HERG. Taken together, this mutant may cause subtle changes in HERG channel functions (I(Kr)) in vivo. In this case, genetic background and unexpected bradycardia may have contributed to the development of long qt syndrome.- - - - - - - - - - ranking = 1keywords = syncope (Clic here for more details about this article) |
10/85. Polymorphic ventricular tachycardia in a woman taking cesium chloride.A 47-year-old patient presented with syncope and recurrent episodes of polymorphic ventricular tachycardia. She had evidence of prolonged QT interval by ECG and had been taking cesium as a dietary supplement. Correction of the hypokalemia and discontinuation of the cesium resulted in normalization of the QT interval during follow-up with no further recurrence of ventricular arrhythmias. The use of this drug is potentially hazardous as it may induce fatal ventricular arrhythmias.- - - - - - - - - - ranking = 1keywords = syncope (Clic here for more details about this article) |
| | Next -> |