Toshihiko Asanuma

Relationship Between Progressive Microvascular Damage and Intramyocardial Hemorrhage in Patients With Reperfused Anterior Myocardial Infarction Myocardial Contrast Echocardiographic Study

BACKGROUND Recent studies indicated that ischemic microvascular damage may be reversible or progressive after coronary reflow. Intramyocardial hemorrhage is a phenomenon that reflects severe microvascular injury. We examined the relationship between temporal changes in microvascular perfusion patterns detected by myocardial contrast echocardiography (MCE) and intramyocardial hemorrhage detected by magnetic resonance imaging (MRI) in patients with acute myocardial infarction (AMI). METHODS AND RESULTS The study population consisted of 24 patients with anterior AMI. All patients underwent MCE shortly after reflow and in the chronic stage (a mean of 31 days after reflow). Wall motion score (WMS) was determined as the sum of 16 segmental scores (dyskinetic/akinetic=3 to normal=0) at days 1 and 31. Gradient-echo acquisition and gadolinium-DTPA-enhanced spin-echo MRI were performed within 10 days after reflow. In MCE shortly after reflow, 16 patients (67%) showed contrast enhancement and the other 8 patients (33%) showed a sizable contrast defect. In the chronic stage, a persistent contrast defect was observed in 7 of 8 patients with a contrast defect shortly after reflow. Consistent contrast enhancement was observed in 12 of 16 patients (75%) with contrast enhancement shortly after reflow, indicating that a contrast defect newly appeared in 4 patients (25%). Intramyocardial hemorrhage was detected in 9 patients (38%): 5 of 7 patients with a persistent contrast defect and in all 4 patients with a new appearance of a contrast defect during the chronic stage. The patients without hemorrhage showed a significant improvement in WMS compared with patients with hemorrhage at day 31 (5+/-5 versus 19+/-6, P<.0005). CONCLUSIONS These results suggest that irreversible microvascular damage to the ischemic myocardium may cause intramyocardial hemorrhage after reflow, associated with impaired recovery of left ventricular function. Contrast enhancement within the risk area shortly after reflow does not necessarily indicate long-term microvascular salvage.

Assessment of Myocardial Ischemic Memory Using Speckle Tracking Echocardiography

OBJECTIVES The aim of this study was to evaluate which regional myocardial parameters derived from speckle tracking echocardiography could demonstrate myocardial ischemic memory in a brief ischemia-reperfusion dog model. BACKGROUND Myocardial ischemic memory imaging, denoting the visualization of abnormalities provoked by ischemia and sustained even after restoration of perfusion, can convey important clinical information. We previously reported that post-systolic shortening (PSS) remains in the risk area after recovery from brief ischemia. However, it is still unclear whether abnormalities in other regional deformation parameters persist after relief from brief ischemia. METHODS Echocardiographic data were chronologically acquired from 11 dogs during 2 min of coronary occlusion followed by reperfusion. Regional systolic and diastolic deformation parameters, including parameters related to PSS, were measured from radial and circumferential strain and from strain rate analyzed in the risk and normal areas. Strain imaging diastolic index (SI-DI), which had been proposed as a parameter for assessing ischemic memory, was also calculated. RESULTS Peak systolic strain, end-systolic strain, and peak systolic strain rate decreased in the risk area during occlusion but recovered to the baseline level immediately after reperfusion. Strain rate during early diastole decreased during occlusion; however, the decrease did not persist after reperfusion. Post-systolic strain index (PSI) and time-to-peak strain index, which are parameters of PSS, increased during occlusion. These increases persisted until 10 to 20 min after reperfusion (circumferential PSI: 0.02 ± 0.04 [baseline] vs. 0.08 ± 0.04 [20 min], p < 0.05). SI-DI did not show a significant change during occlusion because of a large variation. CONCLUSIONS Although abnormalities of PSS-related parameters alone persisted after recovery from 2-min occlusion, abnormalities of other deformation parameters, such as strain rate during early diastole, did not. These data suggest that assessment of PSS by speckle tracking echocardiography is useful for detecting myocardial ischemic memory.

Assessment of Myocardial Ischemic Memory Using Persistence of Post-Systolic Thickening After Recovery From Ischemia

OBJECTIVES We sought to investigate the time course of post-systolic thickening (PST) and systolic abnormality after recovery from brief myocardial ischemia. BACKGROUND Myocardial ischemic memory imaging, denoting the visualization of abnormalities provoked by ischemia and sustained even after restoration of perfusion, is desirable and allows after-the-fact recognition of ischemic insult. PST offers a sensitive marker of myocardial ischemia, but whether this abnormal thickening remains after relief from brief ischemia is unclear. METHODS Tissue strain echocardiographic data were acquired from 27 dogs under 2 different conditions of myocardial ischemia induced by either brief coronary occlusion (15 or 5 min) followed by reperfusion (Protocol 1) or by dobutamine stress during nonflow-limiting stenosis (Protocol 2). Peak systolic strain and post-systolic strain index (PSI), a parameter of PST, were analyzed. RESULTS In Protocol 1, peak systolic strain was significantly decreased in the risk area during occlusion. This decrease in peak systolic strain in the 15-min group did not completely recover to baseline levels even 120 min after reperfusion, whereas the decrease in the 5-min group recovered immediately after reperfusion. We found that PSI was significantly increased during occlusion, but increased PSI in the 5-min group remained until 30 min after reperfusion (-0.19 +/- 0.18 [baseline] vs. 0.19 +/- 0.14 [30 min], p < 0.05) despite the rapid recovery of peak systolic strain. In Protocol 2, increased PSI was sustained until 20 min after the end of dobutamine infusion (-0.26 +/- 0.11 [baseline] vs. -0.16 +/- 0.10 [20 min], p < 0.05), although peak systolic strain recovered by 5 min after the end of dobutamine infusion. CONCLUSIONS PST remained longer than abnormal peak systolic strain after recovery from ischemia. Assessment of PST may be valuable for detecting myocardial ischemic memory.

Energy loss in the left ventricle obtained by vector flow mapping as a new quantitative measure of severity of aortic regurgitation: a combined experimental and clinical study.

AIMS In aortic regurgitation (AR), energy loss (EL) produced by inefficient turbulent flow may be a burden to the heart predicting decompensation. We attempted to quantify EL in AR induced in an acute dog model and in patients with chronic AR using novel echocardiographic method vector flow mapping (VFM). METHODS AND RESULTS In 11 anaesthetized open-chest dogs, AR was induced by distorting the aortic valve with a pigtail catheter, in totally 20 cases. Regurgitant fraction was determined using pulsed Doppler echocardiography, <30% considered mild to moderate (Group 1, n = 11) and ≥30% moderate to severe (Group 2, n = 9). The clinical study consisted of 22 patients with various degrees of AR; 11 mild to moderate (Group 1) and 11 moderate to severe (Group 2), and compared with 12 normals. VFM is based on continuity equation applied to colour Doppler and speckle tracking velocities, acquired from apical long-axis image. EL was calculated frame by frame, averaged from three beats. In the dog study, diastolic EL increased significantly with severity of AR (baseline vs. Group 1 vs. Group 2: 3.8 ± 1.6 vs. 13.0 ± 5.0 vs. 22.4 ± 14.0 [J/(m s)], ANOVA P = 0.0001). Similar to dogs, diastolic EL also increased in humans by the severity of AR (control vs. Group 1 vs. Group 2: 2.8 ± 1.5 vs. 14.3 ± 11.5 vs. 18.6 ± 2.3 [J/(m s)], ANOVA P = 0.001). CONCLUSION VFM provides a promising method to quantify diastolic EL in AR. Diastolic EL increases in AR proportional to its severity. EL may be useful to determine the severity of disease from the aspect of cardiac load.

Intravascular ultrasound evaluation of plaque distribution at curved coronary segments

Although the distribution of atherosclerosis at the curved coronary segments has implications for atherogenesis and interventional procedures, few data exist regarding the plaque distribution in these sites. Therefore, we prospectively analyzed the intravascular ultrasound images of 55 coronary sites from 37 patients where the atherosclerotic plaque and pericardium were simultaneously demonstrated by intravascular ultrasound. The pericardial images were defined as a high-intensity linear echo image moving during cardiac cycles outside the vessel wall. By the line that was parallel to the pericardial image, the vessel area was divided into 2 semicircles with the same area, namely myocardial and pericardial sides. In each side, the maximal thickness, area, and percent area of plaque were measured. The plaque thickness and area of the myocardial side were significantly greater (1.5 +/- 0.5 mm, 4.9 +/- 2.1 mm or 66%, mean +/- SD) than those of the pericardial side (1.1 +/- 0.4 mm, 3.5 +/- 2.1 mm2 or 45%, p < 0.01). The maximal plaque thickness was positioned at the point with a mean angle of 139 +/- 37 degrees from the point just facing the pericardial image, indicating that atherosclerosis was eccentrically located on the opposite side of the pericardium in these coronary segments, and suggesting that the side of the pericardial image represents the outer curvature of the coronary artery. These results indicate that the pericardial images can be seen by intravascular ultrasound, facilitating the recognition of the disease distribution in situ. The eccentric plaque located on the inner wall at the curved coronary segments, probably due to uneven local shear stress, may have implications for the interventional procedures for these segments.

Guidelines from the Japanese Society of Echocardiography: Guidance for the management and maintenance of echocardiography equipment

Echocardiography plays a pivotal role as an imaging modality in modern cardiology practice. Information derived from echocardiography is definitely helpful for patient care. The Japanese Society of Echocardiography has promoted echocardiography in routine clinical and research use. One of the missions of the Society is to provide information that is useful for high-quality examinations. To ensure this, we believe that equipment in good condition and a comfortable environment are important for both patient and examiner. Here, the Guideline Preparation Committee of the Japanese Society of Echocardiography has established brief guidance for the routine use of echocardiography equipment.

Assessment of Dyssynchronous Wall Motion During Acute Myocardial Ischemia Using Velocity Vector Imaging

OBJECTIVES The purpose of this study was to investigate the diagnostic value of velocity vector imaging (VVI) for detecting acute myocardial ischemia and whether VVI can accurately demonstrate the spatial extent of ischemic risk area. BACKGROUND Using a tracking algorithm, VVI can display velocity vectors of regional wall motion overlaid onto the B-mode image and allows the quantitative assessment of myocardial mechanics. However, its efficacy for diagnosing myocardial ischemia has not been evaluated. METHODS In 18 dogs with flow-limiting stenosis and/or total occlusion of the coronary artery, peak systolic radial velocity (V(SYS)), radial velocity at mitral valve opening (V(MVO)), peak systolic radial strain, and the percent change in wall thickening (%WT) were measured in the normal and risk areas and compared to those at baseline. Sensitivity and specificity for detecting the stenosis and occlusion were analyzed in each parameter. The area of inward velocity vectors at mitral valve opening (MVO) detected by VVI was compared to the risk area derived from real-time myocardial contrast echocardiography (MCE). Twelve image clips were randomly selected from the baseline, stenosis, and occlusions to determine the intra- and inter-observer agreement for the VVI parameters. RESULTS The left circumflex coronary flow was reduced by 44.3 +/- 9.0% during stenosis and completely interrupted during occlusion. During coronary artery occlusion, inward motion at MVO was observed in the risk area. Percent WT, peak systolic radial strain, V(SYS), and V(MVO) changed significantly from values at baseline. During stenosis, %WT, peak systolic radial strain, and V(SYS) did not differ from those at baseline; however, V(MVO) was significantly increased (-0.12 +/- 0.60 cm/s vs. -0.96 +/- 0.55 cm/s, p = 0.015). Sensitivity and specificity of V(MVO) for detecting ischemia were superior to those of other parameters. The spatial extent of inward velocity vectors at MVO correlated well with that of the risk area derived from MCE (r = 0.74, p < 0.001 with a linear regression). CONCLUSIONS The assessment of VVI at MVO permits easy detection of dyssynchronous wall motion during acute myocardial ischemia that cannot be diagnosed by conventional measurement of systolic wall thickness. The spatial extent of inward motion at MVO suggests the size of the risk area.

Effects of supine and lateral recumbent positions on pulmonary venous flow in healthy subjects evaluated by transesophageal Doppler echocardiography

OBJECTIVES This study attempted to evaluate the effects of supine and lateral recumbent positions on pulmonary venous flow by transesophageal Doppler echocardiography in healthy subjects. BACKGROUND Although transesophageal echocardiographic examination is usually performed with the patient lying in the left lateral decubitus or supine position, little attention has been paid to the effects of these positions on pulmonary venous flow. METHODS We performed pulsed Doppler transesophageal echocardiography of the left and right pulmonary veins in 16 normal subjects as they lay in the left and right lateral decubitus and supine positions. RESULTS Data are reported as mean value +/- SD. Adequate recordings were obtained in 12 subjects (75%). In the left pulmonary vein, peak systolic velocity and time-velocity integral of systolic flow increased significantly in the left compared with the right lateral decubitus position (56 +/- 12 vs. 44 +/- 13 cm/s, p < 0.05, and 15 +/- 4 vs. 9 +/- 4 cm, p < 0.05, respectively). In the right pulmonary vein, peak systolic velocity and time-velocity integral of systolic flow decreased significantly in the left compared with the right lateral decubitus position (38 +/- 10 vs. 48 +/- 9 cm/s, p < 0.05, and 9 +/- 2 vs. 12 +/- 2 cm, p < 0.05, respectively). There were no significant differences between positions in peak diastolic flow velocity, time-velocity integral of diastolic flow or peak velocity of flow reversal at atrial contraction. CONCLUSIONS Pulmonary venous systolic peak velocities and time-velocity integrals of systolic flow increase when the pulmonary venous recording is from the recumbent subjects lower side. Therefore, the effects of position should be considered in evaluating left ventricular diastolic function by transesophageal Doppler echocardiography.

Myocardial ischaemia and post-systolic shortening

The assessment of regional wall motion is useful to identify myocardial ischaemia because wall motion abnormalities occur relatively upstream in the ischaemic cascade. Echocardiography is widely used for this, but the subjectivity of visual observation may hamper accurate evaluation. The analysis of myocardial velocity and strain by tissue Doppler and speckle tracking echocardiography has allowed the quantitative assessment of regional wall motion and facilitated the detection of subtle myocardial deformation that is difficult to identify by conventional methods, such as post-systolic shortening (PSS). PSS is defined as myocardial shortening that occurs after end-systole (or aortic valve closure), and it is observed in the myocardium with regional contractile dysfunction. In experimental and clinical studies, it has been reported that the assessment of PSS is superior to that of conventional parameters such as wall thickening or peak systolic strain in detecting acute ischaemia and diagnosing coronary artery disease. Moreover, it has recently been found that PSS remains after recovery from brief ischaemia despite the rapid recovery of peak systolic strain. The assessment of PSS allows after-the-fact recognition of myocardial ischaemic insults and is expected to be used for ischaemic memory imaging. In this review, the usefulness of the assessment of PSS for the diagnosis of acute ischaemia and ischaemic memory is demonstrated, and issues that need to be resolved for the widespread use of this assessment in the echocardiographic laboratory are discussed.

Doppler estimation of pulmonary artery end-diastolic pressure using contrast enhancement of pulmonary regurgitant signals

Pulmonary artery (PA) end-diastolic pressure is used as an estimate of PA wedge pressure. We evaluated contrast enhanced pulmonary regurgitant signals in the assessment of PA end-diastolic pressure in 24 patients in a critical care unit. Right atrial pressure was estimated by the percent decrease of the inferior vena caval diameter with inspiration. Weak or absent pulmonary regurgitant signals were enhanced by sonicated albumin (Albunex) in 23 patients (96%). The Doppler-determined PA end-diastolic pressure (the sum of the pulmonary regurgitant pressure gradient at end-diastole and the right atrial pressure) was significantly correlated with the catheter-determined PA end-diastolic pressure (y = 0.85x + 1.72, r = 0.93). Compared with invasive hemodynamic monitoring, the contrast-enhanced Doppler technique using Albunex is effective for measuring PA end-diastolic pressure, even in critically ill patients.