Sack S, Heinzel F, Dagres N, Wieneke H, Erbel R
Abteilung für Kardiologie, Zentrum für Innere Medizin, Universitätsklinikum Essen.
Herz. 2001 Feb;26(1):84-8. doi: 10.1007/pl00002010.
With regard to epidemiological aspects, heart failure has been shown an increasing incidence in constrast to coronary artery disease which counts decreasingly due to secondary and primary prevention. The present data show an incidence for heart failure of 2% per year. 4-5 million people are newly affected by the disease. The prognosis is limited after diagnosis is confirmed. According to the US Framingham study, the median life expectancy is 3.2 and 5.4 after diagnosis for male and female, respectively. For patients in an advanced stage of the disease the mortality rate is 27% within 3 years. AV SEQUENTIAL PACING: The introduction of AV sequential pacing by the Austrian group of Margarete Hochleitner in 1992 showed an improved left ventricular systolic function, an improved clinical benefit in terms of NYHA classification, an enhanced left ventricular ejection fraction, an improved systolic and diastolic blood pressure, a reduction of the heart-chest relationship as well as a reduction of the resting hart rate and the echocardiographic dimension parameters.
First experimental approach for biventricular stimulation, which means the simultaneous activation of the right and the left chamber, relied on the observation of a distorted ventricular activation due to the presence of a bundle branch block. The bundle branch block is a result of the dilatation of the myocardial fibers, death of myocardial cells which are replaced by fibrous tissue. Resynchronization of both ventricles was associated with an improved left ventricular function and improved diastolic relaxation. Clinical studies of patients with heart failure, severe left ventricular systolic dysfunction, and left bundle branch block have shown that systolic function can be improved by electrically stimulating the site of late activation. The magnitude of the improvement seems to be associated with the duration of the intrinsic surface QRS complex and whether the ventricle ipsilateral with the conduction defect is stimulated. The effect of ventricular resynchronization therapy was optimized by timing of atrioventricular activation associated with a decrease in both systolic and diastolic mitral regurgitation.
The prognosis of patients with end-stage heart failure is limited by two determinants: myocardial pump failure and sudden (arrhythmogenic) cardiac death. Due to the fact that the incidence for sudden cardiac death is considerably high in patients with end-stage heart failure it is reasonable to include the implantation of cardioverters/defibrillaters (ICD) in the concept of biventricular stimulation.
在流行病学方面，与冠状动脉疾病相比，心力衰竭的发病率呈上升趋势，而冠状动脉疾病由于二级和一级预防，发病率在下降。目前的数据显示，心力衰竭的年发病率为2%。每年有400万至500万人新患此病。确诊后预后有限。根据美国弗明汉姆研究，男性和女性确诊后的中位预期寿命分别为3.2年和5.4年。对于疾病晚期患者，3年内死亡率为27%。房室顺序起搏：1992年奥地利玛格丽特·霍克莱特纳团队引入房室顺序起搏，结果显示左心室收缩功能得到改善，纽约心脏协会（NYHA）分级方面的临床获益得到改善，左心室射血分数提高，收缩压和舒张压改善，心胸比例降低，静息心率和超声心动图尺寸参数降低。
双心室刺激的首次实验方法，即同时激活右心室和左心室，依赖于对由于存在束支传导阻滞而导致的心室激活异常的观察。束支传导阻滞是心肌纤维扩张、心肌细胞死亡并被纤维组织取代的结果。双心室再同步与左心室功能改善和舒张期松弛改善相关。对心力衰竭、严重左心室收缩功能障碍和左束支传导阻滞患者的临床研究表明，通过电刺激晚期激活部位可改善收缩功能。改善程度似乎与体表QRS波群的固有持续时间以及是否刺激传导缺陷同侧的心室有关。通过房室激活的时机优化心室再同步治疗，可减少收缩期和舒张期二尖瓣反流。
终末期心力衰竭患者的预后受两个因素限制：心肌泵衰竭和心脏性猝死。由于终末期心力衰竭患者心脏性猝死的发生率相当高，因此在双心室刺激概念中纳入植入心脏复律除颤器（ICD）是合理的。
