组织多普勒与心脏再同步化起搏治疗

慢性充血性心力衰竭是临床上的一大难题，死亡率较高。相当一部分心力衰竭患者常合并房内、房室及心室内传导延迟，这些传导障碍的出现常加重心力衰竭。虽然药物治疗在不断发展，但目前抗心力衰竭的药物治疗对这部分伴房室和（或）室内传导障碍者常无效且不能改善预后。心脏再同步化起搏治疗（cardiac resynchronization therapy，CRT）却初步显示了对药物疗效不佳的心力衰竭患者临床应用的良好前景。CRT是指对已存在电机械活动失同步的衰竭心脏，通过心房和左右心室多部位组合同步起搏，来纠正、恢复和改善心脏的同步性，提高心脏作功效率和射血功能的治疗方法。CRT拓宽了器质性心脏病终末期的治疗方法，是近些年来国内外心脏起搏与电生理学界研究的热点课题。     

自触发心脏磁共振成像

目的探讨和实现一种自触发磁共振心脏成像(CMRI)。方法将心电图(ECG)信号和呼吸信号从监测信号中提取出来,然后将K空间数据重新排列、重建,得到心脏图像。结果自触发CMRI克服了传统的导联法难以获得稳定ECG信号的缺点,可提高扫描效率,得到高品质的亮血和黑血小鼠心脏电影图像。结论采用自触发CMRI可以实现小鼠心脏电影成像以及黑血成像,并用于评价其心脏结构和功能。     

Cardiac resynchronization therapy guided by cardiovascular magnetic resonance

Cardiac resynchronization therapy (CRT) is an established treatment for patients with symptomatic heart failure, severely impaired left ventricular (LV) systolic dysfunction and a wide (> 120 ms) complex. As with any other treatment, the response to CRT is variable. The degree of pre-implant mechanical dyssynchrony, scar burden and scar localization to the vicinity of the LV pacing stimulus are known to influence response and outcome. In addition to its recognized role in the assessment of LV structure and function as well as myocardial scar, cardiovascular magnetic resonance (CMR) can be used to quantify global and regional LV dyssynchrony. This review focuses on the role of CMR in the assessment of patients undergoing CRT, with emphasis on risk stratification and LV lead deployment.     

Magnetic resonance criteria for future trials of cardiac resynchronization therapy.

Current patient selection criteria for Cardiac Resynchronization Therapy (CRT), an efficacious treatment for heart failure, include no measure of disconjugate cardiac contractility other than prolonged QRS on electrocardiogram. Using cardiac magnetic resonance imaging, we examined the roles of cardiac asymmetry, asynchrony, and circumferential strain in DCC with the principal aim of generating a robust numerical index for use in future trials of CRT. Standard cardiac magnetic resonance imaging was done on a GE 1.5 Tesla Signa LX MRI clinical scanner (GE Healthcare, Milwaukee, WI, USA) and analyzed by MASS Analysis (MEDIS, Leiden, The Netherlands). The methods were evaluated in eleven patients with advanced heart failure due to ischemic and non-ischemic cardiomyopathy, who did not qualify under current criteria for CRT, five CRT candidates pre-op and eleven normal subjects. Using t-test and standardized differences (SD = sd/diff, Power (N) = number of patients to reach p < .05) we determined efficacy. Indices of asymmetry and asynchrony (Ism and Isn, respectively) could be measured with accuracy and provided excellent statistical power when used as surrogate markers to delineate heart failure and CRT patients from control subjects. Asymmetry and asynchrony in heart contraction are both critical components of dilated cardiomyopathy that can be improved by CRT. Magnetic resonance asynchrony is efficacious in screening patients and should now be compared with recently published echocardiography data to improve outcome for this costly but valuable therapy.     

组织同步显像在心脏再同步优化治疗中的应用

目的：探讨组织同步显像在心脏再同步优化治疗的应用价值。方法：32例行双心室优化起搏治疗的心衰患者，术前，术后1个月、3个月、6个月分别进行组织同步显像及常规超声检查，在心尖四腔心切面、两腔心切面、三腔心切面分析组织同步指数及达峰时间差。常规超声指标包括：左室舒张末内径、收缩末内径、二尖瓣反流面积、左室射血分数、二尖瓣舒张充盈时间、主动脉时间速度积分。结果：与术前相比，术后1个月、3个月、6个月组织同步指数及达峰时间差降低（P〈0.05）。左室舒张末内径、收缩末内径、二尖瓣反流面积逐渐减小（P〈0．05），左室射血分数、二尖瓣舒张充盈时间、主动脉时间速度积分逐渐增加（P〈O．05）。结论：组织同步显像可以快捷地评价机械不同步，为心脏再同步优化治疗提供有力的手段。     

组织多普勒成像技术对心脏再同步化治疗的评价

目的探讨应用组织多普勒成像(TDI)技术评价心脏再同步化治疗(CRT)慢性心力衰竭患者的临床应用价值。方法选择拟行CRT的慢性心力衰竭患者31例,应用TDI测量收缩速度达峰时间判断左室收缩延迟部位,根据左室电极的位置是否与收缩延迟部位相符,将患者分为电极位置和收缩延迟部位符合者20例(A组)和不符合者11例(B组)。应用常规超声心动图及TDI技术观察两组术前及术后1,3,6个月左室收缩功能指标和心脏同步性参数的变化,评价CRT治疗效果。结果所有患者术前TDI技术评估均提示存在左室内收缩不同步,TDI技术能够指导左室电极植入理想靶静脉。术后1,3,6个月,患者的纽约心脏病协会心功能(NYHA)分级、6min步行距离、左室射血分数(LVEF)、左室舒张末期内径(LVEDd)、二尖瓣反流(MR)程度及室间机械延迟(IVMD)、左室12节段达峰时间标准差(Ts-SD)、左室内最晚收缩-最早收缩(Ts max-min)均较术前明显改善,术后6个月各参数改变最明显(P<0.05)。术后6个月,A,B组间NYHA分级、6min步行距离、LVEF、MR程度、IVMD、Tsmax-min及Ts-SD比较,差异均有统计学意义(均P<0.05)。结论 TDI技术可以用于慢性心力衰竭患者接受CRT的筛选,并能指导左室电极植入位置和评价疗效。     

Cardiac resynchronization therapy guided by late gadolinium-enhancement cardiovascular magnetic resonance

Background

Myocardial scarring at the LV pacing site leads to incomplete resynchronization and a suboptimal symptomatic response to CRT. We sought to determine whether the use of late gadolinium cardiovascular magnetic resonance (LGE-CMR) to guide left ventricular (LV) lead deployment influences the long-term outcome of cardiac resynchronization therapy (CRT).

Methods

559 patients with heart failure (age 70.4 ± 10.7 yrs [mean ± SD]) due to ischemic or non-ischemic cardiomyopathy underwent CRT. Implantations were either guided (+CMR) or not guided (-CMR) by LGE-CMR prior to implantation. Fluoroscopy and LGE-CMR were used to localize the LV lead tip and and myocardial scarring retrospectively. Clinical events were assessed in three groups: +CMR and pacing scar (+CMR+S); CMR and not pacing scar (+CMR-S), and; LV pacing not guided by CMR (-CMR).

Results

Over a maximum follow-up of 9.1 yrs, +CMR+S had the highest risk of cardiovascular death (HR: 6.34), cardiovascular death or hospitalizations for heart failure (HR: 5.57) and death from any cause or hospitalizations for major adverse cardiovascular events (HR: 4.74) (all P < 0.0001), compared with +CMR-S. An intermediate risk of meeting these endpoints was observed for -CMR, with HRs of 1.51 (P = 0.0726), 1.61 (P = 0.0169) and 1.87 (p = 0.0005), respectively. The +CMR+S group had the highest risk of death from pump failure (HR: 5.40, p < 0.0001) and sudden cardiac death (HR: 4.40, p = 0.0218), in relation to the +CMR-S group.

Conclusions

Compared with a conventional implantation approach, the use of LGE-CMR to guide LV lead deployment away from scarred myocardium results in a better clinical outcome after CRT. Pacing scarred myocardium was associated with the worst outcome, in terms of both pump failure and sudden cardiac death.     

Ultrafast pulse sequence techniques for cardiac magnetic resonance imaging

Cardiac magnetic resonance imaging is a rapidly emerging field that has seen tremendous advances in the past decade. Central to the development of effective imaging strategies has been the advent of high-performance gradient hardware and the exploitation of their speed characteristics through specialized pulse sequences well suited for cardiac imaging. These advances have facilitated unprecedented acquisition times that now approach echocardiographic frame rates, while maintaining excellent image quality. This article provides a detailed overview of advanced pulse sequence technology and approaches currently taken to maximize speed performance and image quality. In particular, segmented K-space techniques that include single-echo and multiecho spoiled gradient-echo imaging as well as steady-state free precession imaging are discussed. Finally, spiral and fast spin-echo techniques are explored. Examples of common applications of these pulse sequences are presented.     

New directions in cardiac magnetic resonance imaging

Cardiac MRI is poised for a major change: Recent development of echoplanar imaging, or "instant" scanning, offers the possibility of studying myocardial perfusion with contrast agents. Moreover, newer contrast agents are being developed to study various aspects of myocardial function. Techniques of MR angiography have progressed: Noninvasive coronary angiography for detecting asymptomatic atherosclerosis of at least the proximal region of the coronary arteries appears possible in the near future. MRI has also been used to solve a long-standing problem in cardiac imaging: the absence of point-to-point correspondence in tomographic images of the heart from diastole to systole. Through tissue tagging, MRI offers the unique possibility of noninvasively assessing local and regional ventricular deformation more accurately than any other method available today.     

Impact of cardiac magnetic resonance imaging on cardiac device and surgical therapy: a prospective study

Cardiac magnetic resonance (CMR) imaging may allow more appropriate selection of patients for cardiac device implantation and/or cardiac surgery. In this prospective observational study we evaluated the impact of CMR imaging on cardiac device and surgical therapy. All CMR examinations performed in a single centre over a 2 year period were prospectively recorded in a dedicated database under 4 clinical pathways [cardiomyopathy, viability, tumour/mass and arrythmogenic right ventricular cardiomyopathy (ARVC)]. Baseline data entered included planned cardiac device implantation and/or cardiac surgical intervention. Patients were contacted 6 months following CMR to evaluate the impact of CMR on planned therapy. Cost savings due to CMR were calculated as the number of surgical or device procedures averted following CMR scanning multiplied by their respective cost weights. Of 732 CMR examinations performed, the clinical pathway was cardiomyopathy in 488 (67 %), ARVC in 118 (16 %), viability in 92 (12 %) and tumour/mass in 34 (5 %). Six month follow-up was available in 666/732 patients. Following CMR, 56/150 (37 %) of patients with an initial plan for device implantation or cardiac surgery, did not undergo the planned intervention (P < 0.001, one-sample exact binomial test). Of 516 patients without an initial device or surgical plan, 33 (6 %) CMR resulted in device implantation or cardiac surgery (P < 0.001, Chi squared). Overall, the estimated saving due to CMR-guided management changes was AUD$737,270. CMR has a significant impact on patient management and offers potential cost savings with respect to selection of device and surgical therapy for cardiac disease.     

Advances in cardiac magnetic resonance imaging and computed tomography

Imaging evaluation of the heart encompasses structural evaluation of the chambers, valves and coronary arteries, and functional evaluation, including assessment of perfusion, wall motion and myocardial viability. Magnetic resonance imaging is well established for the structural and functional evaluation of the heart, and benefits from direct multiplanar image acquisition and a lack of ionizing radiation. Magnetic resonance imaging assessment of myocardial viability after myocardial infarction appears to be helpful in predicting benefit from revascularization procedures. Magnetic resonance imaging continues to hold promise as the least invasive method of coronary artery evaluation, and continuing developments are improving image quality and decreasing examination time. The development of cardiac-gating techniques for multidetector computed tomography has the potential to provide widespread availability of cardiac computed tomography. Short examination times and straightforward scanning procedures promise a convenient method for the examination of cardiac structure and function. However, this convenience must be balanced against radiation dose and contrast-media requirements when determining the appropriate use of cardiac computed tomography. Computed tomography coronary-calcium scoring can aid in the prediction of significant coronary events in all but the lowest-risk patients. The high negative-predictive value of computed tomography coronary angiography may allow some patients to avoid cardiac catheterization, but its role in the assessment of patients with moderate coronary atherosclerosis remains unclear. New software tools can assist in the complex and tedious analysis of the large volumes of data produced by these examinations.     

Non-invasive cardiac mapping for non-response in cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an effective intervention in selected patients with moderate-to-severe heart failure with reduced ejection fraction and abnormal left ventricular activation time. The non-response rate of approximately 30% has remained nearly unchanged since this therapy was introduced 25 years ago. While intracardiac mapping is widely used for diagnosis and guidance of therapy in patients with tachyarrhythmia, its application in characterization of the electrical substrate to elucidate the mechanisms involved in CRT response remain anecdotal. In the present review, we describe the traditional determinants of CRT response before presenting novel non-invasive techniques used for CRT optimization. We discuss efforts to identify the target electrical substrate to guide the deployment of pacing electrodes during the operative procedure. Non-invasive body surface mapping technologies such as ECG imaging or ECG belt enables prediction of acute and chronic CRT response. While electrical dyssynchrony parameters provide high predictive accuracy for CRT response when obtained during intrinsic conduction, their predictive value is less when acquired during CRT or LV-pacing.

Key messages

• Classic predictors of CRT response are female gender, NYHA class ≤ III, left ventricular ejection fraction ≥25%, QRS duration ≥150 ms and estimated glomerular filtration rate ≥60 mL/min.
• ECG-imaging is a comprehensive non-invasive mapping system which allows to express the amount of electrical asynchrony of a CRT candidate.
• Non-invasive body surface mapping technologies enables excellent prediction of acute and chronic CRT response before implantation.
• When performed during CRT or LV-pacing, the added value of these mapping systems remains unclear.

     

化学交换饱和转移在心脏磁共振中的研究进展

化学交换饱和转移（chemical exchange saturation transfer，CEST）MRI成像是一种新兴的基于饱和质子与周围水中质子化学交换的体内分子成像技术，将传统的解剖成像扩展到组织酸碱度成像及体内多种生化代谢成像，且具有无辐射、非侵入性等显著优势，成为时下研究一大热点。目前CEST在心血管磁共振成像的应用研究刚刚起步，本文主要对其原理及其在心脏磁共振的临床应用价值研究进展予以详细阐述。     

适用于三腔心脏起搏器的冠状动脉介入技术

慢性心力衰竭是临床的常见病及疑难病,心脏再同步化治疗是治疗心力衰竭的有效方法,但是其操作难度大,风险高,尤其是左心室电极的植入尤其困难,冠状动脉介入技术,如双导丝技术,锚定技术,鞘中鞘技术在左心室电极植入中的应用,可以提高手术成功率,增加安全性,值得临床推广.     

ASCI 2010 standardized practice protocol for cardiac magnetic resonance imaging: a report of the Asian society of cardiovascular imaging cardiac computed tomography and cardiac magnetic resonance imaging guideline working group

These practice guidelines are recommended by the Asian Society of Cardiovascular Imaging (ASCI), the sole society in Asia designated for cardiovascular imaging, to provide a framework to healthcare providers for suggested essential elements in cardiac magnetic resonance (CMR) examinations of different disease spectra. The guideline is composed of recommendations on the general technique, acquisition of some basic modules, and protocols on stress tests. The protocols for specific diseases are provided in a table format for quick reference to be easily utilized for everyday clinical CMR.     

超声心动图在心脏再同步化治疗中的应用

心衰患者普遍存在不同程度的心室内或心室间的不同步化运动,心脏再同步化治疗明显增强患者的心肌功能,改善患者的临床症状,随着心脏再同步化治疗的应用,超声心动图在心脏再同步化治疗中以其无创性和可重复性的特点用于筛选接受心脏再同步化治疗的患者,预测和评价心脏再同步化治疗的短期和长期效果,其优越性日益显著.本文就心肌机械性不同步运动的形式以及超声心动图在心室再同步化治疗前、治疗中以及治疗后的应用及其亟待解决的问题进行综述.     

Rate-dependent aberrancy and cardiac resynchronization therapy

Left bundle branch block (LBBB) can result in significant dyssynchrony in left ventricular (LV) contraction, ultimately leading to cardiac remodeling. LBBB can be rate dependent and may appear with LV systolic dysfunction. Cardiac resynchronization therapy (CRT) has been demonstrated to improve hemodynamics as well as clinical symptoms in patients with LBBB. We describe the case of a 57-year-old man who underwent CRT implantation due to exertional dyspnea, rate-dependent LBBB, and impaired left LV systolic function.     

Functional magnetic resonance imaging in oncology for diagnosis and therapy monitoring

Functional magnetic resonance imaging is rapidly evolving as a capable noninvasive assessment tool for oncology to improve diagnosis and to monitor therapy. Current clinical techniques are based on microcirculation imaging using extracellular low molecular weight contrast agents such as gadopentetate dimeglumine and analogues. The temporal evolution of the enhancement visualizes the angiogenic properties of lesions with regard to vascular density and permeability, heterogeneity, and changes during therapy.