小剂量多巴酚丁胺-异舒吉超声心动图负荷试验检测冠心病人存活心肌

目的：探讨异舒吉（isoket）对小剂量多巴酚丁胺超声负荷试验（LDDSE）的影响。方法：将39例研究对象依据冠脉造影的结果分为3组：对照组（CON）12例、冠心病1组（CAD1）15例和冠心病2组（CAD2）12例,其中CAD2行LDDSE＋isoket,其余两组行LDDSE,以冠脉介入性治疗（PCI）后室壁运动改善的结果作为评价LDDSE的标准。结果：isoket可以明显增加心率,降低收缩压,但对舒张压影响轻微。CAD2组存活心肌的检出率和敏感性明显高于CAD1组。结论：isoket可提高LDDSE存活心肌检出率。     

术前经胸及经食管超声心动图在二尖辦修复术中的应用

目的对二尖瓣修复术前运用经胸及经食管超声心动图技术诊断二尖瓣反流（mitral regurgitation，MR）病变的精确度进行比较。方法2004年3月至2006年6月，我院共有243例MR患者拟行二尖瓣修复术。术前所有患者均行经胸超声心动图（transthoracic echocardiography，TTE）检查，41例患者行经食管超声心动图（transeophageal echocardiography，TEE）检查。将术前超声心动图资料与术中所见进行比较，分别对TTE及TEE的诊断精确度进行评价。结果术前TTE及TEE与手术吻合率分别为81．48％及87．80％（P=0．325）。TTE与TEE的诊断吻合率为73．17％。两种技术检测脱垂、腱索断裂、瓣膜穿孔或裂缺、腱索异常以及赘生物等病变的敏感性、特异性以及诊断精确度无统计学差异。8例患者行换瓣术，其余235例行二尖瓣修复术。术前是否接受TEE检查对修复成功率无显著影响。结论TTE是检测各种二尖瓣反流性病变的有效手段，能满足绝大多数患者的术前诊断需要，在MVR中具有重要的应用价值。     

The role of stress echocardiography in children

Exercise and pharmacological stress echocardiography are well-accepted techniques of evaluating coronary artery disease in adults. In children, however, experience with stress echocardiography is limited and continues to evolve. The objective of this focused review was to describe the experience with exercise and dobutamine stress echocardiography in the pediatric population, with an emphasis on technique, current indications, and future directions. Experience is reported in children with prior Kawasaki disease or heart transplant recipients, as well as patients with congenital coronary abnormalities. In addition, stress echocardiography has been used in patients who have undergone coronary artery bypass graft surgery to evaluate short- and long-term graft patterning. Stress echocardiography appears to be a feasible, safe, and useful modality for the noninvasive assessment of flow-limiting stenosis in the pediatric population and can be used serially in the routine follow-up and risk stratification in children at risk for coronary events.     

Risk of thromboembolism in acute atrial fibrillation or atrial flutter

Atrial fibrillation (AF) is the most common sustained cardiac dysrhythmia, predominating in the elderly, with stroke as a potentially devastating complication. Prevention of the thromboembolic sequelae from AF remains a central focus of practicing clinicians. Although the risk of thromboembolism in chronic AF is well recognized, less is known about the potential risk of systemic embolism in acute AF. In addition, recent data support the notion of a group at considerable risk of embolism from atrial flutter, an arrhythmia typically believed to bestow little increased risk of thromboembolism. The mechanism of thrombus formation, embolization, and resolution in atrial arrhythmias is not well defined, particularly in that of acute AF or atrial flutter. The traditional concept proposes that atrial thrombus forms only after > 2 days of AF and embolizes by being dislodged from increases in shear forces. This widely accepted concept further holds that newly formed atrial thrombus, in the setting of AF, organizes over a span of 14 days. The results of studies based on observations from transesophageal echocardiography examinations have provided provocative insight into the temporal sequence of atrial thrombus formation, embolization, and resolution in AF or atrial flutter and have expanded the traditional concept of thromboembolism in these atrial dysrhythmias. Namely, left atrial thrombus may form before the onset of AF in the face of sinus rhythm. Conversion to sinus rhythm may increase the thrombogenic milieu of the left atrium. Importantly, atrial thrombus may form in the acute phase of AF. Last, thrombi may require > 14 days to become immobile or to resolve. Findings similar to those of acute AF have been reported in patients with atrial flutter and coexisting cardiac pathology. On the basis of these emerging insights fostered by the use of transesophageal echocardiography, it appears appropriate to consider anticoagulation in patients presenting with acute AF or atrial flutter with coexisting cardiac pathology predisposing to left atrial thrombus.     

Fibrotic aortic stenosis in a patient with dwarfism

In this report, we present an adult patient with dwarfism who had severe aortic stenosis with markedly thickened fibrotic valve leaflets without calcification. These findings were well demonstrated by both two- and three-dimensional transesophageal echocardiography and confirmed at surgery and by pathological examination.     

Severe dynamic obstruction of the left ventricular outflow tract induced by dobutamine

We present the case of a 63-year-old man who developed a subaortic gradient of 182 mmHg during an echocardiographic pharmacological stress study with dobutamine.     

Active vegetations can be differentiated from chronic vegetations by visual inspection of standardized two-dimensional echocardiograms

The ability to differentiate active from chronic valvular vegetations (VEGs) by digital image processing and by visual observation was evaluated in 18 patients with a clinical diagnosis of infective endocarditis (IE). Two-dimensional echocardiographic (2-DE) examinations were performed on all patients at diagnosis and after a mean period of 52 days. Two comparable images (active and chronic) from the same patient and in the same phase of the cardiac cycle were digitized, magnified, and displayed on a high resolution monitor. The mean pixel intensity (MPI) was 72+/-14 in the active stage and 143 +/-23 in the chronic stage (P<0.0001). The VEG size was 0.64+/- 0.15 cm(2) in the active stage and decreased to 0.46+/-0.17 cm(2) in the chronic stage (P<0.001). Two experienced echocardiographers, who were blinded to the age of the VEGs, identified each echocardiographic image as active or chronic based on visual observation of density of the VEGs. The VEGs were correctly identified as active or chronic in 17 out of the 18 patients. In summary, although digital image processing of 2-DE may be useful, the density of VEGs assessed by visual inspection will help differentiate between active and chronic VEGs of IE. The standardization procedure at the time of the initial study and use of identical gain settings in subsequent studies are key factors in making this distinction.     

Age dependency of myocardial structure: a quantitative two-dimensional echocardiographic study in a normal population

Histological changes of the myocardium occur with aging due to an increase in collagen content, hypertrophy of fibers, and patchy fibrosis. Quantitative analysis of conventional echocardiographic images provides an in vivo assessment of myocardial structure by the evaluation of the gray level distribution; with this technique, a relation between myocardial fibrosis and pathological ultrasonic response has been documented. The aim of this study was to evaluate the relation between ultrasonically assessed myocardial structure and age in a normal population. Seventy-eight subjects (47 men; mean age, 51 years; age range, 23-87 years) without apparent cardiovascular and systemic disease underwent conventional two-dimensional echocardiographic examinations. Still frames at end-diastole from apical four-chamber view were digitized and converted in matrices of 256 x 256 pixels. First-order statistical analysis was performed to describe a region of interest in the interventricular septum. The following parameters were studied: mean (gray level amplitude), standard deviation (overall contrast), uniformity (tonal organization), and entropy (tendency of gray levels to be spread). Myocardial structure was assessed in 75 of 78 subjects, divided into three groups: I, age 23-40 years; II, age 41-65 years; and III, > 65 years. Significant differences for all the parameters were found between the age groups. Age correlated directly with mean and entropy (r = 0.77 and 0.69, respectively) and inversely with uniformity (r = 0.70). Our results suggest that quantitative echocardiography can reveal age-related changes in myocardial structure that are characterized by a greater echogenicity and loss in tonal organization, possibly due to increased collagen content within the fibers.     

Two-dimensional and Doppler echocardiographic assessment of variably shaped ductus arteriosus by the parasternal approach

Summary Parasternal two-dimensional and Doppler echocardiography were compared with angiographic, surgical, and postmortem data in 213 patients with various forms of congenital heart disease for its accuracy in determining patency and anatomy of the ductus arteriosus (DA). The age range of the examined patients was from 1 day to 4 years (mean, 7.4 months). Echocardiography was always performed before any invasive procedure. An adequate window for imaging the DA was obtained by parasternal, two-dimensional echocardiography in 209 patients (98%). A persistent ductus arteriosus (PDA) was detected by invasive methods in 79 of 209 patients (38%), and by two-dimensional and Doppler echocardiography in 76 (sensitivity, 96%; specificity, 100%). The echocardiographic and angiographic findings agreed closely as to the duct's morphology. Our technique permits an accurate visualization of the duct in neonates, infants, and small children with various forms of congenital heart disease.     

Assessment of cardiac function by M-mode echocardiography in selenium-deficient phenylketonuric children

Selenium (Se) deficiency is associated with cardiac and skeletal muscle dysfunction. Twenty well children aged 2-16 years (10 male) attending the Phenylketonuria (PKU) Clinic at the Royal Children's Hospital, Brisbane, had low Se levels (mean 0.29 +/- 0.02 s.e.m. mumol/L; normal range 0.56-1.16 mumol/L). Their myocardial function was assessed at rest and after exercise provocation by M-mode echocardiography in order to exclude occult left ventricular dysfunction. At rest, fractional shortening (FS) was normal (mean 38.1 +/- 1.1 s.e.m. %, n = 20). After exercise, FS increased significantly (P less than 0.001) from 37.6 +/- 1.4% to 44.3 +/- 1.2%, n = 12). This was associated with a significant rise (P less than 0.001) in heart rate (HR) from 77.3 +/- 3.1 beats/min to 125.8 +/- 5.2 beats/min (n = 12). The normal resting FS and normal increase in FS and HR with exercise is evidence against significant cardiac impairment in this group of Se-deficient children.