心脏离子通道病引起的晕厥

心脏离子通道病是近10年来被人们逐渐认识的一类原发性心电疾病,其病因是编码心肌细胞上各主要离子通道亚单位的基因突变导致相应通道功能异常。已明确的病种有长QT综合征、B rugada综合征、特发性心室颤动、儿茶酚胺敏感的多形性室性心动过速、短QT综合征、孤立性心房颤动、病窦综合征、心脏传导阻滞等,这些疾病可引起晕厥甚至猝死。本文综述了这类疾病的分子致病机制、诊断标准、临床表现及治疗。     

短QT间期综合征

短QT间期综合征是一种由于心脏离子通道的基因突变导致相应的离子通道功能异常,引起心肌细胞复极加快、QT间期缩短而易致家族性心源性猝死的常染色体显性遗传的综合征。本文就现有的研究对其流行病学、基因研究、QT间期缩短机理、临床表现、治疗、预后等作一综述。     

长QT综合征的治疗进展

长QT综合征（long QT syndrome,LQTS）属于离子通道病.分先天性和获得性两种.前者由编码心脏离子通道蛋白的基因突变所致,后者产生于药物、电解质不平衡及器质性心脏病对心脏离子通道的影响.其心电图特点为QT间期延长,T波改变以及尖端扭转性室性心动过速（室速）为特点的多形室速（TdP）,导致心室颤动（室颤）甚至引起心脏性晕厥和猝死.LQTS虽然不是临床常见病,但并非罕见.     

先天性长QT综合征的药物治疗

先天性长QT综合征（long QT syndrome,LQTS）是遗传性心脏离子通道疾病,临床特征表现为心电图上QT间期显著延长和尖端扭转型室速（torsadede pointes,TdP）反复发作,是心脏结构正常的患者发生心源性猝死的最常见原因之一。     

短QT综合征的热点问题

一.特发性短QT综合征对心电图学的重要意义特发性短QT综合征（idiopathic short QT syndrome,简称SQTs）是最晚被发现和命名的一种异质性、遗传性心肌细胞离子通道病。以心电图QT间期异常缩短为主要特征,可致房性和室性快速心律失常以及心脏性猝死。多发于青年后期和成年早期,偶发于婴儿和老年期。     

不应局限于离子通道--遗传性长QT间期综合征研究进展及启示

遗传性长QT间期综合征(Long QT Syndrome，LQTS，简称长QT综合征)是因编码心肌细胞膜、质膜离子通道及相关蛋白的基因突变而引起的一组临床紊乱综合征，临床以心电图QT间期延长、QT—T多变、多形性室性心动过速及心脏猝死为特征，它是引起儿童和青年人意外死亡的重要原因之一，因而备受关注。     

短QT综合征诊断与治疗

摘要：短QT综合征(SQTS)是以QT间期缩短为特征、与心源性猝死(SCD)相关、常伴有家族性心房颤动和(或)心室颤动,而心脏结构正常的离子通道疾病。目前已知7个致病基因,包括KCNH2、KCNQ1、KCNJ2、CACNAIC、CACNB2B、CACNA2D1及SCN5A基因,分别编码于钾通道、钙通道和钠通道亚单位。复极离散度增加和不应期的缩短被认为是SQTS心律失常的分子机制。SCD的一级和二级预防均推荐植入心脏复律除颤器。奎尼丁是有效的治疗药物。      

遗传性心律失常综合征

任何一个编码离子通道的基因突变便可以使离子通道功能受损,因此而引发的疾病称“离子通道病”。离子通道病可导致心律失常,其中心源性猝死(SCD)是其最严重的临床表现。这是一些遗传性疾病,以恶性室性心律失常为主要临床表现,不伴有心脏结构异常,其中致死性心律失常最引人注目。目前,一些遗传性心律失常综合征,其遗传学基础已经明确的单基因遗传病也可以称为遗传性心电疾病。见表1。本文将基于目前的研究结果,按表现型的不同,分为长QT综合征、Brugada综合征、短QT综合征及其他遗传性心律失常综合征分别予以介绍。长QT综合征Jervell和La…     

遗传性长QT间期综合征的研究进展

遗传性长 QT间期综合征 (L QTS)是儿童和年轻人发作性晕厥和心源性猝死的主要原因之一 ,本文结合新近文献 ,对遗传性 L QTS的分子遗传机制、离子通道生理病理改变、临床表现、诊断标准及治疗原则的最新研究予以总结。     

长QT间期延长综合征研究进展

长QT间期延长综合征(LQTS)是一种病因不明,心电图表现为QT间期延长,可伴T波及U波异常的一组综合征,其最主要临床表现为晕厥及猝死。随着相关基础研究取得进展,发现先天性LQTS患者突变基因不同,在临床症状表现上也各有特点。现就最近对本病的基因突变型与临床表现之间的关系进行综述。     

The cardiac component of cardiac cachexia

Background Recent evidence suggests the importance of noncardiac mechanisms in the genesis of the syndrome of cardiac cachexia. This raises the question of the relative role of the heart itself in this syndrome. This study sought to assess the cardiac dimensions, mass, and function and changes in these parameters over time in patients with chronic heart failure with and without cachexia. Methods Doppler echocardiography was performed in 28 patients with nonedematous weight loss (>7.5% over a period of >6 months) compared with 56 matched patients without weight loss in a ratio of 1:2 (age 71 ± 13 vs 67 ± 8 years, P = .07; New York Heart Association class 2.9 ± 0.7 vs 2.6 ± 0.6, P = .08). In 18 cachectic and 35 noncachectic patients with previous echocardiographic recordings, we analyzed the changes in left ventricular (LV) dimensions and mass over time. Results Cardiac dimensions including LV diastolic (69 ± 9 mm vs 67 ± 13 mm) and systolic cavity diameter (58 ± 11 mm vs 55 ± 15 mm), LV mass (480 ± 180 g vs 495 ± 190 g), and LV systolic and diastolic function including fractional shortening (16% ± 10% vs 18% ± 10%), isovolumic relaxation time (29 ± 22 ms vs 36 ± 27 ms), and E/A ratio (2.7 ± 1.6 vs 3.3 ± 2.9) did not differ between cachectic and noncachectic patients (all P > .1). By analyzing changes in LV mass over time, we found an increase (>20%) in 2 (11%) cachectic and 14 (40%) noncachectic patients and a decrease in LV mass (>20%) in 9 (50%) cachectic and 8 (23%) noncachectic patients (χ² test, P < .05). Conclusions Although no specific cardiac abnormality could be detected echocardiographically in cachectic patients compared with patients with noncachectic chronic heart failure in a cross-sectional study, over time a significant loss of LV mass (>20%) occurs more frequently in patients with cardiac cachexia. (Am Heart J 2002;144:45-50.)     

Analysis of cardiac symptoms preceding cardiac arrest

Prodromal symptoms and cardiac history were examined in 227 patients with coronary artery disease who were successfully resuscitated after out-of-hospital cardiac arrest. Cardiac arrest was sudden—with either no symptoms or symptoms for less than 1 hour—in 71% of the patients. Nonsudden death—death occurring after more than 1 hour of symptoms—occurred in 29% of the patients. A history of cardiovascular disease was present in 85% of patients with sudden cardiac arrest and in 83% with nonsudden arrest. Cardiac arrest occurred without symptoms in 38% of the patients with sudden cardiac arrest and was the first expression of coronary artery disease in 4% of the entire study group. This study indicates that cardiac arrest usually occurs with symptoms and almost always in the setting of a history of cardiovascular disease.     

Occult cardiac lymphoma presenting with cardiac tamponade

Subxiphoid pericardiostomy is the procedure of choice for treatment of a pericardial effusion with tamponade. We report a case in which this procedure not only failed to reveal the presence of an occult malignancy, but also resulted in a recurrent symptomatic effusion.     

External cardiac pacing during in-hospital cardiac arrest

External noninvasive cardiac pacing offers a rapid and simple method of pacing the heart during an emergency. It has been suggested that early use of cardiac pacing for bradycardia or asystole may improve survival in patients who have cardiac arrest. To investigate this possibility 58 consecutive episodes of cardiac arrest occurring on the medical wards or emergency room. Twenty-six episodes underwent external noninvasive pacing for bradycardia or asystole refractory to standard drugs. Only 2 patients survived, and survival could be directly attributed to pacing in only 1 of them. Of the 32 episodes not undergoing pacing, 23 had transient asystole or bradycardia, 13 of which rapidly responded to medications. The 17 cases (53%) not undergoing pacing survived. In conclusion, when bradycardia or asystole during cardiac arrest fails to respond to standard pharmacologic measures, it is an indicator of severe myocardial damage, and attempts at cardiac pacing rarely improve survival.     

Acute cardiac tamponade due to cardiac actinomycosis

Cardiac actinomycosis occurs in less than 2 percent of the patients with infections due to Actinomyces israelii. We describe the findings in a patient with acute cardiac tamponade who survived through pericardial drainage and aggressive medical therapy. Although uncommon, this disorder is important to recognize because it is curable with current medical and surgical therapy.     

心脏骤停和心脏性猝死

心脏性猝死(SCD)是目前社会关注的热点问题.2005年WHO的数据表明,在全球死于心脑血管疾病的约1700万人群中,40%～50%是SCD.SCD虽然有多种定义,但目前一般认为是在1 h内出现的由于心血管原因导致的非预期死亡事件或无目击者的死亡事件.心脏骤停(SCA)不等同于SCD,SCA如果救治失败会引起真正的SCD.     

Sodium-induced cardiac aldosterone synthesis causes cardiac hypertrophy

High sodium intake causes cardiac hypertrophy independently of increases in blood pressure. Aldosterone is synthesized in extraadrenal tissues such as blood vessels, brain, and heart. Effects of 8 weeks of high sodium intake on cardiac aldosterone synthesis, as well as cardiac structure, mass, and aldosterone production, levels of mRNA coding for aldosterone synthase (CYP11B2) and the angiotensin II AT1 receptor, were studied in normotensive Wistar-Kyoto (WKY) rats. Isolated rat hearts were perfused for 2 hr, and the perfusate was analyzed by high-performance liquid chromatography and mass spectrometry. Aldosterone synthase activity was estimated from the conversion of [14C]deoxycorticosterone to [14C]aldosterone. Levels of mRNA for CYP11B2 and AT1 receptor were determined by competitive polymerase chain reactions. A high sodium intake for 8 weeks produced left ventricular hypertrophy without elevation of blood pressure. Plasma aldosterone concentrations and plasma renin concentrations were decreased by high sodium intake. Aldosterone production, activity of aldosterone synthase, and expression of mRNA for CYP11B2 and AT1 receptor were increased in hearts of rats with high sodium intake. These results suggest that high sodium intake increases cardiac aldosterone synthesis, which may contribute to cardiac hypertrophy independently of the circulating renin-angiotensin-aldosterone system.