Comparison of myocardial velocities obtained with magnetic resonance phase velocity mapping and tissue Doppler imaging in normal subjects and patients with left ventricular dyssynchrony

PURPOSE: To compare longitudinal myocardial velocity and time to peak longitudinal velocity obtained with magnetic resonance phase velocity mapping (MR-PVM) and tissue Doppler imaging (TDI), and to assess the reproducibility of each method. MATERIALS AND METHODS: Longitudinal myocardial velocity was measured by TDI and MR-PVM in 10 normal volunteers and 10 patients with dyssynchrony. The reproducibility of MR-PVM and TDI was assessed on repeated measurements in the 10 normal volunteers. RESULTS: MR and TDI measurements of longitudinal myocardial velocity correlated well (r = 0.86) in both normal subjects and patients with dyssynchrony. However, myocardial velocities measured with MR consistently exceeded velocities measured with TDI. MR and TDI agreed strongly in measuring the time to peak velocity (r = 0.97). The reproducibility of TDI and MR-PVM appeared similar in measuring peak velocities (13.1% vs. 11.0%, respectively; P = NS) and time to peak velocity (9.1% vs. 5.7%, respectively; P = NS). CONCLUSION: Excellent correlation and reproducibility were observed between MR-PVM and TDI in measuring longitudinal myocardial velocity and time to peak velocity in both normal subjects and patients with dyssynchrony.     

Biomonitoring equivalents for hexachlorobenzene

Recent efforts worldwide have resulted in a growing database of measured concentrations of chemicals in blood and urine samples taken from the general population. However, few tools exist to assist in the interpretation of the measured values in a health risk context. Biomonitoring equivalents (BEs) are defined as the concentration or range of concentrations of a chemical or its metabolite in a biological medium (blood, urine, or other medium) that is consistent with an existing health-based exposure guideline. This study reviews available health-based exposure guidance values for hexachlorobenzene (HCB) from Health Canada, the United States Environmental Protection Agency (US EPA), the US Agency for Toxic Substances and Disease Registry (ATSDR) and World Health Organization (WHO). HCB liver tissue concentrations in chronic rodent bioassays and information on human elimination rates and tissue distribution of HCB were extrapolated to estimate serum lipid-adjusted HCB concentrations that are consistent with the exposure guidance values for HCB. Estimated serum lipid-adjusted HCB concentrations ranging from 16 to 250 ng/g lipid were consistent with non-cancer-based exposure guidance values from various agencies. Concentrations associated with cancer risk-specific doses at target risk levels of interest were also estimated. These BE values may be used as screening tools for evaluation of population biomonitoring data for HCB in a risk assessment context and can assist in prioritization of the potential need for additional risk assessment efforts for HCB relative to other chemicals.     

Cardiac Resynchronization Therapy in Patients With Heart Failure and Narrow QRS Complexes

Background

Cross correlation analysis (CCA) using tissue Doppler imaging has been shown to be associated with outcome after cardiac resynchronization therapy (CRT) in patients with heart failure (HF) with wide QRS. However, its significance in patients with narrow QRS treated with CRT is unknown.

蒽环类药物对肿瘤患者左心功能影响的组织多普勒评价

目的探讨组织多普勒技术(TDI)在评价蒽环类药物(ATC)对肿瘤患者左心功能早期损害的临床应用价值。方法测定并比较26例肿瘤患者ATC化疗前和化疗后6个月的常规超声心动图参数及TDI参数。结果TDI显示ATC化疗后二尖瓣环的收缩期运动速度峰值(Sm)及舒张早期运动速度峰值(Em)较化疗前明显降低(P<0.05),心房收缩期运动速度峰值(Am)较化疗前明显升高(P<0.01),Em/Am较化疗前明显降低(P<0.01),但舒张早期左室充盈峰速度(E)、心房收缩期左室充盈峰速度(A)、E/A、E峰减速时间(DT)、左室等容舒张时间(IVRT)及射血分数(EF)、短轴缩短率(FS)等常规心功能指标化疗前后差异无显著性(P>0.05)。结论TDI技术能更早、更敏感地评价ATC对肿瘤患者左室功能损害。     

Factors affecting the arterial distension waveform derived from tissue Doppler imaging (TDI): an in vitro study on precision

An investigation was made into the effect of acquisition parameters on the distension waveform estimated from tissue Doppler imaging (TDI). Physiological distension waveforms were generated using a compliant wall phantom. Distensions derived over a range of scanning geometries and transducer pressures were compared with those obtained in optimised scanning conditions. The estimated maximum distension decreased with scanning depth by 7% between 20 mm and 44 mm below the phantom surface, with an increase in transducer-vessel angle (by 22% from 0 degrees to 24 degrees ) and with a decrease in scan plane-vessel coincidence (by 34% from coincidence to 2 mm from the vessel central axis). An increase with transducer pressure was observed (by 20% from contact to high exerted pressure).     

Tissue Doppler imaging in coronary artery diseases and heart failure

Recent studies have explored the prognostic role of TDI-derived parameters in major cardiac diseases, such as coronary artery disease (CAD) and heart failure (HF). In these conditions, myocardial mitral annular systolic (S') and early diastolic (E') velocities have been shown to predict mortality or cardiovascular events. In heart failure non invasive assessment of LV diastolic pressure by transmitral to mitral annular early diastolic velocity ratio (E/E') is a strong prognosticator, especially when E/E' is > or =15. Moreover, other parameters derived by TDI, as cardiac time intervals and Myocardial Performance Index, might play a role in the prognostic stratification in CAD and HF. Recently, a threedimensional (3-D) TDI imaging modality, triplane TDI, has become available, and this allows calculation of 3-Dvolumes and LV ejection fraction. We present a brief update of TDI.     

Improved coronary artery blood flow following the correction of systolic dyssynchrony with cardiac resynchronization therapy

Background

Coronary blood flow (CBF) is improved by cardiac resynchronization therapy (CRT) and impaired by right ventricular apical (RVA) pacing in patients with heart failure. However, the underlying mechanism remains unclear.

Methods

Twenty-nine non-ischemic heart failure patients who responded to CRT underwent transthoracic echocardiography examination including both left anterior descending (LAD) CBF and tissue Doppler imaging in 3 pacing modes: intrinsic conduction, RVA pacing and biventricular (BiV) pacing. LAD velocity-temporal integral (LAD-VTI) and duration were measured. Systolic dyssynchrony was assessed with the standard deviation of a 12-left ventricular segmental model (Ts-SD).

Results

BiV pacing improved while RVA pacing reduced CBF compared to intrinsic conduction (all p < 0.05). Both Ts-SD and ventricular septal velocity deteriorated during RVA pacing but improved during BiV pacing (all p < 0.05). When systolic dyssynchrony was induced, lower LAD-VTI (9.5 ± 3.4 versus 12.7 ± 5.1 cm, p = 0.001) and shorter LAD diastolic duration (483 ± 92 versus 542 ± 106 ms, p = 0.010) were detected than synchronous status. Systolic dyssynchrony was inversely related to septal velocity (r = − 0.41), p<0.001 and LAD-VTI (r = − 0.30, p = 0.007), with the latter found to be moderately correlated to septal velocity (r = 0.30, p = 0.007).

Conclusion

Regional LAD flow was improved in patients subjected to BiV but worsened in those treated with RVA pacing in non-ischemic heart failure CRT responders. Systolic dyssynchrony was more commonly observed in patients subjected to RVA pacing. Reduction of septal velocity with dyssynchrony may directly lead to reduced LAD flow. Improvement of septal velocity by CRT and hence LAD flow may be an important mechanism in determining the response to CRT.     

甲苯二异氰酸酯所致兔气道高反应性

目的观察甲苯二异氰酸酯（ＴＤＩ）对气道反应性的影响。方法将１０只健康家兔按体重配对，随机等分为２组，观察吸入１２６．７９±１．４２μｇ／ｍ３ＴＤＩ前、后及１％乙酰胆碱（ＡＣＨ）雾化吸入后的气道反应性变化。结果ＴＤＩ吸入前，两组动物对１％ＡＣＨ无明显反应。吸入ＴＤＩ１小时后，呼吸频率明显减慢。１％ＡＣＨ雾化吸入１分钟后，气道反应性明显增高，ＰａＣＯ２明显降低，ＰａＯ２明显升高。肺组织病理切片示：细、小支气管周围炎性细胞浸润，气道上皮及纤毛脱落。对照组无上述改变。结论低浓度ＴＤＩ可诱发兔气道高反应性。     

Immunologic cross-reactivity between different albumin-bound isocyanates

Sera of six workers with conclusive evidence for IgE-mediated sensitization to isocyanates were used for evaluation of immunologic cross-reactivities among eight different isocyanate-protein conjugates. In all cases RAST and/or skin-test investigations revealed the presence of IgE antibodies reacting specifically with HSA conjugated with those isocyanates to which workers were exposed as well as with other isocyanates with which they had not been in contact. By the RAST inhibition technique, moderate to strong mutual cross-reactivities between all tested isocyanate-HSA conjugates--even between aromatic and aliphatic ones--could be demonstrated in tests with five sera. The magnitudes of cross-reactivities differed, however, from one patient to another. One serum contained IgE antibodies that were almost completely specific to TDI-HSA; with this serum only weak cross-reactivities with other isocyanate conjugates could be demonstrated. These results indicate the predominance of closely related antigenic determinants in HSA conjugated with different isocyanates. The common antibody-binding regions are obviously recognized to different extents by antibodies of clinically sensitized workers, indicating individual differences in specificities and avidities of antibody populations. Nearly complete lack of IgE binding of ovalbumin-bound TDI in RAST and RAST inhibition indicates carrier-specific antigenicity of isocyanate-protein conjugates. In addition, since unmodified HSA did not bind IgE, antigenic determinants of the conjugates studied should be predominantly formed by the isocyanate-protein bond regions and concurrently by neighboring amino acid residues of the HSA molecule.