Objective: To examine the efficacy of the intravenous myocardial contrast echocardiography (MCE) for detection of the territory of the coronary bypass graft. Methods: The subjects were 5 beagles having a bypass tube between the left circumflex and carotid artery. MCE was performed with bolus injection of Optison during short axis view recording using harmonic and ECG-triggered modes of every two cardiac cycles. Time video-intensity curve was obtained at the lateral (perfused by the bypass) and the septal wall (perfused by the native coronary artery). Their peak intensities and time interval between these two peaks were measured. Selective MCE into the bypass tube was performed to confirm the territory of the bypass. Flow volume of the bypass was also measured. Results: The bypass area was clearly recognized by delayed opacification in comparison with the native coronary artery's area. Time lag of opacification between the two areas showed a good hyperbolic correlation with bypass flow, and was almost identical to the theoretically calculated time lag (r=0.889, p<0.0001). Conclusion: Both the area and flow volume of coronary bypass were diagnosed by using intravenous MCE.
OBJECTIVES: Mitral valve closure produces a flow which propagates through the left atrium (LA) to the pulmonary vein (PV) and forms a small flow reversal (C wave) on the PV flow pattern. We examined whether propagation of mitral closure flow into LA might reflect LA compliance in patients with atrial fibrillation (AF). METHODS: We recorded PV flow velocity pattern using transesophageal echocardiography in 73 patients with AF. They were divided into 3 groups according to the estimated severity of LA damage; almost normal (Group I, 16 patients with lone AF), mildly damaged (Group II, 23 patients), and severely damaged LA function (Group III, 34 patients). C wave peak velocity (CV), the time from Q wave on ECG to the C wave peak (QC) and QC divided by LA long-axis diameter (QC/LAD) were obtained. Of the study population, in 18 patients with mitral stenosis who underwent percutaneous mitral valvotomy, mean LA compliance was calculated by dividing cardiac stroke volume by systolic rise in LA pressure. RESULTS: QC and QC/LAD proportionally prolonged as the disease severity increased (QC; 84±23 vs. 93±21 vs. 107±27 ms, p<0.01, QC/LAD; 1.44±0.32 vs. 1.47±0.32 vs. 1.79±0.55ms/mm, p<0.05 for Group I, II and III, respectively). QC and QC/LAD showed significant negative correlations with mean LA compliance (p<0.05). CONCLUSION: Propagation of a flow into LA produced by mitral closure may provide new noninvasive indexes to assess LA compliance in patients with AF.
Background. Discrepancies between LV function and its filling pressure are typically characterized with severe dysfunction and normal filling pressure, suggesting reduced preload. Reduced preload can cause lower early to late diastolic mitral flow velocity ratio (E/A) on the Doppler echocardiogram. Therefore, we hypothesized that the relation between LV function and filling pressure is poorer in patients with mitral flow E/A < 1.0, however, the same relation is better in those with E/A ≥1.0. Objectives. The present study sought to investigate and compare the relation between LV filling pressure and indices of LV function, including the recently proposed Doppler Tei index, between patients with mitral flow E/A < 1.0 and those with the E/A ≥ 1.0. Methods. LV end-diastolic and mid-diastolic (before atrial contraction: pre-A) pressures were directly measured by catheterization in 74 consecutive patients with normal sinus rhythm. Tei index was measured from pulsed Doppler LV inflow and outflow velocity recordings, as the sum of isovolumetric contraction and relaxation time divided by LV ejection time. Indices of cardiac function including LV end-diastolic and end-systolic volumes, LV ejection fraction, left atrial dimension, mitral flow E/A, deceleration time of E velocity, and its slope were also measured by Doppler echocardiography. Results. In all subjects, there were no significant or relatively weak correlations between the LV filling pressures and indices of LV function (r2 = 0.05 ∼ 0.27, N.S. ∼ p < 0.0001). In patients with E/A < 1.0, the correlations were not significant for all indices of LV function. However, multiple indices of LV function, especially the Tei index, showed significant and better correlations with both LV end-diastolic and pre-A pressures (r2 = 0.66 and 0.63, p < 0.0001, respectively). Conclusions. Correlations between LV filling pressure and indices of LV function are worse and not significant in patients with mitral flow E/A < 1.0, however, the correlations are better and significant in patients with the E/A ≥ 1.0. Indices of LV function, especially Tei index, allows noninvasive estimation of LV diastolic filling pressure in patients with mitral E/A ≥ 1.0.
Background: Since regional tissue velocities are affected by motion of the adjacent regions as well as the whole heart translational motion, the quantification of wall motion using conventional tissue Doppler method may be questionable. Recently, a new echocardiographic system which enables the calculation of myocardial strain based on tissue Doppler information has been developed. Methods: We investigated whether myocardial strain could quantify regional myocardial contraction in 13 patients with normal wall motion and in 18 patients with wall motion abnormalities. Left ventricular segmental wall motion was assessed with conventional 2-dimensional echocardiography at the apical 2-, 3-, and 4-chamber views. The same views were imaged also with tissue Doppler method to determine regional systolic myocardial strain. Results: By 2-dimensional echocardiography, 230 segments were judged normokinesis, 83 segments hypokinesis and 23 segments showed akinesis. No segments showed dyskinesis. Peak systolic strain values of normokinetic, hypokinetic and akinetic wall segments were significantly different from each other (−20.1±5.5% for normokinesis, −11.9±5.0% for hypokinesis, p<0.0001 vs. normokinesis, and −6.3±3.4% for akinesis, p<0.0001 vs. normokinesis and p<0.0001 vs. hypokinesis) without significant overlap. Peak systolic strain values in normal subjects were similar among all segments, suggesting insignificant regional variations (p=ns). Conclusion: Systolic myocardial strain agreed well with assessed wall motion. Myocardial strain imaging may be a new powerful tool to quantify regional wall contraction.
The widespread use of the pulsed Doppler echocardiography has facilitated the noninvasive evaluation of hemodynamic abnormalities of the left atrium and left ventricle (LV) based on transmitral and pulmonary venous flow velocity patterns. However, it has been shown that loading conditions, especially preload, influence the indices obtained from these velocity patterns. Recently, tissue Doppler imaging (TDI) has been applied to the clinical setting to assess LV myocardial function. In particular, this procedure has the following characteristics: 1) it can provide circumferential and longitudinal information for the LV myocardium; 2) the early diastolic LV myocardial parameters determined by TDI are not influenced by preload; 3) LV myocardial contractility can be evaluated from the early systolic parameters; 4) LV systolic and diastolic asynchrony can be detected; 5) myocardial velocity gradients obtained from color-coded TDI are not influenced by the entire heart motion; and 6) TDI parameters are useful for establishing the prognosis of patients with LV heart failure. In the future, technologic improvements will elucidate the tissue characteristics based on tissue velocity information in patients with myocardial disease or allow the detection of endocardial and/or epicardial involvement of the LV myocardium in patients with ischemic heart disease.
The ultrasound reflection technique was introduced into cardiology in 1953, and in 1955, the ultrasonic Doppler technique was introduced. The dawning stage of ultrasound diagnostics of the heart was the ten year period prior to 1965. During this stage, besides the afore mentioned techniques, there were only a few attempts to use ultrasound for heart diagnostics. In the next age, from about 1965 to 1975, the leading type of the cardiac ultrasound was M-mode echocardiography. M-mode echocardiography was the first generation of ultrasound diagnostics of the heart used in routine practice. This period may be called the age of M-mode echocardiography. During 1975 to 1985, the leading technique was real-time two-dimensional echocardiography, with and without the Doppler mechanism, which was the second generation in routine. This period can be called the age of the two-dimensional echocardiography. The period from 1985 to the present time may be called the age of the color Doppler, which has been the third generation of the cardiac ultrasound. However, since the middle of this last age the cardiac ultrasound has been showing the most diversification of techniques and usages. Therefore, it is uncertain whether the age division as mentioned above can be continued. The period extending over the last age and present time may be the second dawn of the cardiac ultrasound.