The role of frontal plane cardiac axis shift in the diagnosis of wide QRS tachycardia / 实用医学杂志

Objective To explore the value of axis shift between the baseline normal sinus rhythm (NSR) and WCT in diagnosis of wide QRS-complex tachycardia (WCT). Methods 390 surface ECGs of 186 patients with WCT were obtained from April 2012 to April 2018 at Ningbo Medical Center Lihuili Hospital at which the arrhythmia diagnosis was proven by intracardiac electrophysiological study. The axis shift between the baseline NSR and WCT was calculated by table lookup method. Then we analyzed the role of axis shift in diagnosis of WCT. Results Among the 186 patients with WCT, 147 (79.03％) were ventricular tachycardia (VT) , and 39 (20.97％) were supraventricual tachycardia (SVT) with conduction abnormalities. In the 95％ confidence interval, the axis shift showed an outstanding discrimination performance. The area under the ROC curve is 0.708 (0.579-0.817, P =0.007). Compared with left axis deviation, right axis deviation, the right axis deviation of LBBB morphology, the axis shift> 68 degree is more sensitive (53.06％) , and the specificity (91.43％) is also more desirable. Moreover, if the axis shift set> 130 degree, the specificity can reach 100％, and the sensitivity (12.24％) is equivalent to northwestern axis. Conclusion A significant axis shift between the baseline NRS and WCT can distinguish WCT accurately. Given the ease of grasping, it can probably be feasible to popularize as a routine diagnosis method for WCT in primary hospitals.

Progress in research on defective protein trafficking and functional restoration in HERG-associated long QT syndrome / 中华医学遗传学杂志

The human ether-a-go-go related gene (HERG) encodes the α -subunit of the rapid component of the delayed rectifier K(+) channel, which is essential for the third repolarization of the action potential of human myocardial cells. Mutations of the HERG gene can cause type II hereditary long QT syndrome (LQT2), characterized by prolongation of the QT interval, abnormal T wave, torsade de pointes, syncope and sudden cardiac death. So far more than 300 HERG mutations have been identified, the majority of which can cause LQT2 due to HERG protein trafficking defect. It has been reported that certain drugs can induce acquired long QT syndrome through directly blocking the pore and/or affecting the HERG trafficking. The trafficking defects and K(+) currents can be restored with low temperature and certain drugs. However, the mechanisms underlying defective trafficking caused by HERG mutations and the inhibition/restoration of HERG trafficking by drugs are still unknown. This review summarizes the current understanding of the molecular mechanisms including HERG trafficking under physiological and pathological conditions, and the effects of drugs on the HERG trafficking, in order to provide theoretical evidence for the diagnosis and treatment of long QT syndrome.

A novel mutation of the KCNH2 gene in a family with congenital long QT syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To perform mutation analysis in a family with long QT syndrome.</p><p><b>METHODS</b>The medical record of the affected child and his parents were collected. The locus of gene associated with the long QT syndrome was mapped by linkage analysis. Mutation analysis was done by PCR-single strand conformation polymorphism (SSCP) and direct sequencing.</p><p><b>RESULTS</b>A mutation (L539fs/47) and a SNP (L564L) were found in exon 7 of the KCNH2 gene of the proband. The mutation was from the father.</p><p><b>CONCLUSION</b>A novel mutation of L539fs/47 in the KCNH2 gene was identified in the LQTS family, which might be the disease-causing mutation for the family.</p>

A novel mutation-L539fs/47 of hERG in a Chinese long QT syndrome family / 药物分析学报

Objective To identify the mutation of human ether-a-go-go-related gene (hERG) and analyze the clinical characteristics of a Chinese family with long ST syndrome (LQTS). Methods The electrocardiogram and DNA samples were obtained from a Chinese LQTS family of 26 members. Genotype was performed with polymorphic short tandem repeat (STR) markers at the known LQT1, LQT2, and LQT3 loci. SSCP analysis was used to find aberrant conformers. hERG mutation was confirmed by cloning and sequencing. Results Three gene carriers were linked to chromosome 7q35-36, where the potassium channel gene hERG was encoded. A 19-base pair deletion was identified. The mutation was located at nucleotide position 1 619-1 637 between transmembrane domains S4 and S5. Furthermore, A1692G polymorphism was found both in the normal control and patients. Conclusion A novel 19 bp deletion mutation of hERG is identified in a Chinese family. All gene carriers are demonstrated to be typical LQT2 ECG phenotype.

Genotypic diagnosis of long QT syndrome by analysis of candidate genes / 药物分析学报

Objective To diagnose 6 LQTS families by genetic analysis. Methods A total aof 6 LQTS pedigrees with 43 family members were brought together for genetic diagnosis by using short-sequence tandem-repeat (SIR) markers or sequencing. Genomic DNA was extracted from blood samples by standard procedure. STR markers or KCNQ1, KCNH2 and SCN5A were amplified. The haplotype analysis for LQTS was performed. If the family got the negative haplotype analysis, the sequencing was performed. Results LQTS patients were always linkaged with the SCNSA gene in family 1. KCNH2 was linkaged with the disease in family 2 to 5.21 gene carriers were identified from these 5 families. A mutation (A561V-KCNH2) was only found in the proband of family 6 and an SNP (G1691A) was found in all the members of the family. Conclusion Genetic diagnosis can not only improve presymptomatic diagnosis,bnt also provide the basis for personal therapy and research on disease-causing mutations.

Clinical characteristics of 5 Chinese LQTS families and phenotype-genotype correlation / 华中科技大学学报（医学）（英德文版）

In order to assess the clinical manifestations and electrocardiogram (ECG) characteristics of Chinese long QT syndrome (LQTS) patients and describe the phenotype-genotype correlation, the subjects from 5 congenital LQTS families underwent clinical detailed examination including resting body surface ECG. QT interval and transmural dispersion of repolarization (TDR) were manually measured. Five families were genotyped by linkage analysis (polymerase chain reacting-short tandem repeat, PCR-STR). The phenotype-genotype correlation was analyzed. Four families were LQT2, 1 family was LQT3. Twenty-eight gene carriers were (14 males and 14 females) identified from 5 families. The mean QTc and TDRc were 0.56 +/- 0.04 s (range 0.42 to 0.63) and 0.16 +/- 0.04 s (range 0.09 to 0.24) respectively. 35.7% (10/28) had normal to borderline QTc (< or = 0.460 s). There was significant difference in QTc and TDRc between the patients with symptomatic LQTS and those with asymptomatic LQTS, and there was significant difference in TDRc between the asymptomatic patients and normal people also. A history of cardiac events was present in 50% (14/28), including 9 with syncope, 2 with sudden death (SD) and occurred in the absence of beta-blocker. Three SDs occurred prior to the diagnosis of LQTS and had no ECG record. Two out of 5 SDs (40%) occurred as the first symptom. Typical LQT2 T wave pattern were found in 40% (6/15) of all affected members. The appearing-normal T wave was found in one LQT3 family. Low penetrance of QTc and symptoms resulted in diagnostic challenge. ECG patterns and repolarization parameters may be used to predict the genotype in most families. Genetic test is very important for identification of gene carriers.

Clinical characteristics of 5 Chinese LQTS families and phenotype-genotype correlation / 华中科技大学学报（医学）（英德文版）

In order to assess the clinical manifestations and electrocardiogram (ECG) characteristics of Chinese long QT syndrome (LQTS) patients and describe the phenotype-genotype correlation, the subjects from 5 congenital LQTS families underwent clinical detailed examination including resting body surface ECG. QT interval and transmural dispersion of repolarization (TDR) were manually measured. Five families were genotyped by linkage analysis (polymerase chain reacting-short tandem repeat, PCR-STR). The phenotype-genotype correlation was analyzed. Four families were LQT2, 1 family was LQT3. Twenty-eight gene carriers were (14 males and 14 females) identified from 5 families. The mean QTc and TDRc were 0.56 +/- 0.04 s (range 0.42 to 0.63) and 0.16 +/- 0.04 s (range 0.09 to 0.24) respectively. 35.7% (10/28) had normal to borderline QTc (< or = 0.460 s). There was significant difference in QTc and TDRc between the patients with symptomatic LQTS and those with asymptomatic LQTS, and there was significant difference in TDRc between the asymptomatic patients and normal people also. A history of cardiac events was present in 50% (14/28), including 9 with syncope, 2 with sudden death (SD) and occurred in the absence of beta-blocker. Three SDs occurred prior to the diagnosis of LQTS and had no ECG record. Two out of 5 SDs (40%) occurred as the first symptom. Typical LQT2 T wave pattern were found in 40% (6/15) of all affected members. The appearing-normal T wave was found in one LQT3 family. Low penetrance of QTc and symptoms resulted in diagnostic challenge. ECG patterns and repolarization parameters may be used to predict the genotype in most families. Genetic test is very important for identification of gene carriers.

Clinical characteristics of congenital long QT syndrome families / 西安交通大学学报(医学版)

Objective To elucidate the clinical manifestati on s and electrocardiogram characteristics of congenital long QT syndrome families and try to find out the genotype of the long QT syndrome(LQTS) patients. Methods The routine clinical check up and ECG recordings we re done for the 3 family members. Both QT interval and QTc were measured. Diagno stic criteria for LQTS were defined by Schwartz. Results Fifteen family members were identified as with LQTS and 11 members with intermediate probability to LQTS. The clinical manifestatio ns and ECG characteristics were different from each other. Conclusion The clinical manifestations and ECG characterist ics of LQTS patients from family 1,family 2 and family 3 correspond with LQT2, L QT1 and LQT3, which is caused by HERG,KVLQT1 and SCN5A gene mutation.

Effects of non-excitatory electric stimulation on cardiac function in normal and infarcted heart rabbits and it's regional effect on myocardium / 中国病理生理杂志

AIM: To investigate the influences of electric stimulation applied during the absolute refractory period (ARP) on the cardiac function of normal rabbits and rabbits after myocardial infarction (MI) and to observe the regional effects of this electric stimulation. METHODS: 64 rabbits were randomly assigned to normal and MI groups and each group was then divided into the anterior and posterior groups. A thoracotomy was performed 4 weeks after MI in rabbits. One set of electrodes was inserted into the anterior and posterior wall of left ventricle of the anterior and posterior groups, respectively. Current pulses were delivered during the ARP (called CCM) during sinus rhythm in rabbits. The left ventricular systolic pressure (LVSP) and the left ventricular end diastolic pressure(LVEDP) as well as maximum positive and negative left ventricular pressure change (?dp/dt_(max)) were observed. RESULTS: In the normal and MI groups, LVSP, +dp/dt_(max) significantly increased, and LVEDP, -dp/dt_(max) were reduced during CCM stimulation compared with the baseline (P0.05). CONCLUSION: Electric stimulation delivered during the ARP significantly enhances the contractility and the relaxation of myocardium in normal rabbits and rabbits after MI, and the effects of CCM stimulation on heart are regional. [