Left Ventricular Cavity Opacification Research Articles

Echocardiographic Particle Image Velocimetry: A Novel Technique for Quantification of Left Ventricular Blood Vorticity Pattern

In this study, the functionality of echocardiographic particle imaging velocimetry (E-PIV) was compared with that of digital particle imaging velocimetry (D-PIV) in an in vitro model. In addition, its capability was assessed in the clinical in vivo setting to obtain the ventricular flow pattern in normal subjects, in patients with dilated cardiomyopathy, and in patients with mechanical and bioprosthetic mitral valves. A silicon sac simulating the human left ventricle in combination with prosthetic heart valves, controlled by a pulsed-flow duplicator, was used as the in vitro model. Particle-seeded flow images were acquired (1) using a high-speed camera from the mid plane of the sac, illuminated by a laser sheet for D-PIV, and (2) using a Siemens Sequoia system at a frame rate of 60 Hz for E-PIV. Data analysis was performed with PIVview software for D-PIV and Omega Flow software for E-PIV. E-PIV processing was then applied to contrast echocardiographic image sets obtained during left ventricular cavity opacification with a lipid-shelled microbubble agent to assess spatial patterns of intracavitary flow in the clinical setting. The velocity vectors obtained using both the E-PIV and the D-PIV methods compared well for the direction of flow. The streamlines were also found to be similar in the data obtained using both methods. However, because of the superior spatial resolution of D-PIV, some smaller scale details were not revealed by E-PIV. The application of E-PIV to the human heart resulted in reproducible flow patterns in echocardiographic images taken within different time frames or by independent examiners. The E-PIV technique appears to be capable of evaluating the major flow features in the ventricles. However, the bounded spatial resolution of ultrasound imaging limits the small-scale features of ventricular flow to be revealed.

Cardiovascular Imaging of Remote Myocardial Ischemia

Intravenous microbubbles currently are approved by the Food and Drug Administration solely for the purpose of enhancing left ventricular cavity opacification. However, intravenous microbubbles also have been used in several clinical studies to detect myocardial perfusion. Ultrasound imaging of myocardial contrast to detect perfusion abnormalities has significant advantages over other imaging techniques in that it has higher resolution, does not require ionizing radiation, and can be performed at the patient’s bedside. Clinical studies have demonstrated that myocardial contrast echocardiography is useful for detecting coronary artery disease both in the emergency room setting and during stress echocardiography. In these settings, the intravenous microbubbles function as pure intravascular tracers and are not adherent to the vessel wall or taken up by the myocytes. Article p 345 Ligands can be attached to the surface of microbubbles, which results in their binding to specific epitopes upregulated on the endothelial surface. Such binding was used in the study by Villanueva et al1 in the present issue of Circulation . In a rat model, these investigators were able to successfully attach the selectin-targeting tetrasaccharide sialyl Lewisx to phospholipid-shelled microbubbles and to detect myocardial regions that were previously ischemic with a sensitive ultrasound detection scheme. Detection of contrast enhancement from retained microbubbles within the remotely ischemic perfusion …

Pulmonary Transit of Echocontrast Agents during Mechanical Ventilation: A Clinical Transthoracic Echocardiographic Study

In this study, we investigated whether the ultrasound contrast agents Levovist or Sono Vue injected intravenously during mechanical ventilation effectively pass through the pulmonary circulation. With echocardiography, we measured the time for the contrast to pass through the lungs; and the intensity of right and left ventricular cavity opacification at four time points: during spontaneous breathing (baseline), 5 minutes after the beginning of mechanical ventilation, and 5 minutes and 30 minutes after extubation. Forty patients undergoing elective peripheral neurosurgical procedures were prospectively and randomly enrolled: 20 patients received intravenous Levovist 1 g and 20 patients received intravenous Sono Vue 1 mL, at the four predefined time points. After intravenous injection, both Levovist and Sono Vue effectively passed through the lungs and opacified the right and left ventricular cavities, at the four time points. Pulmonary transit times were similar and constant for the two contrast agents tested: 6 +/- 2 seconds at baseline, 5 +/- 2 seconds during mechanical ventilation, 7 +/- 2 seconds at 5 minutes and 6 +/- 2 seconds at 30 minutes after extubation with Levovist; and 6 +/- 4 seconds at baseline, 6 +/- 3 seconds during mechanical ventilation, 6 +/- 2 seconds at 5 minutes and 7 +/- 3 seconds at 30 minutes after extubation with Sono Vue. In all patients, each of the four contrast injections achieved high-grade right and left ventricular chamber opacification. In conclusion, both the ultrasound contrast agents tested in this study, Levovist and Sono Vue, after intravenous injection pass through the pulmonary circulation during mechanical ventilation. Ultrasound contrast agents with these characteristics are suitable for intraoperative organ perfusion studies, with intravenous injection.

Combination of contrast with stress echocardiography: a practical guide to methods and interpretation.

Contrast echocardiography has an established role for enhancement of the right heart Doppler signals, the detection of intra-cardiac shunts, and most recently for left ventricular cavity opacification (LVO). The use of intravenously administered micro-bubbles to traverse the myocardial microcirculation in order to outline myocardial viability and perfusion has been the source of research studies for a number of years. Despite the enthusiasm of investigators, myocardial contrast echocardiography (MCE) has not attained routine clinical use and LV opacification during stress has been less widely adopted than the data would support. The purpose of this review is to facilitate an understanding of the involved imaging technologies that have made this technique more feasible for clinical practice, and to guide its introduction into the practice of the non-expert user.

487 Early changes of left atrial reservoir function after cardioversion of paroxysmal atrial fibrillation predict relapse of arrhythmia

487 Early changes of left atrial reservoir function after cardioversion of paroxysmal atrial fibrillation predict relapse of arrhythmia

Intermittent harmonic imaging and videodensitometry significantly enhance ability of intravenous air-filled ultrasonographic contrast agent to produce ventricular and myocardial opacification

We used visual and videodensitometric evaluation to investigate the influence of intermittent harmonic imaging (IHI) compared with intermittent fundamental imaging on cavity and myocardial signal intensity after administration of the air-filled transpulmonary contrast agent BY963. Twelve patients were studied with intermittent fundamental imaging and IHI after administration of 5 mL and 10 mL of contrast agent. Contrast effect was graded in the parasternal short-axis view. Visually, IHI improved opacification of both the right and left ventricular cavities, especially the left. Densitometrically, right ventricular opacification did not differ significantly between imaging modalities, whereas left ventricular cavity opacification was significantly higher when using IHI. Myocardial opacification was observed in a small minority of segments when assessed by visual estimation, whereas videodensitometry revealed opacification in 42 of 48 anterior, 39 of 48 posterior, and 42 of 48 septal segments. Differences were not significant between doses. We conclude that with IHI and densitometry, air-filled contrast agents like BY963 show significantly improved performance in producing cavity and myocardial contrast effects.

Efficacy and safety of the novel ultrasound contrast agent perflutren (definity) in patients with suboptimal baseline left ventricular echocardiographic images

Suboptimal left ventricular (LV) cavity visualization and endocardial border delineation often compromise the clinical utility of echocardiography. This study examines the safety and efficacy of perflutren, a novel ultrasound contrast agent, for LV cavity opacification and endocardial border delineation in patients with suboptimal baseline echocardiograms. In a multicenter, randomized, placebo-controlled, double-blind trial, 211 patients with suspected cardiac disease and suboptimal baseline echocardiograms were enrolled at 17 sites. Two intravenous injections of either placebo (saline) or perflutren (5 or 10 μl/kg) were given approximately 30 minutes apart. Images of the apical 4- and 2-chamber views were acquired and scored. Perflutren opacified the LV cavity after both dosages (5 and 10 μl/kg dosages). Clinically useful contrast was observed in 89% of patients who received perflutren and in 0% of patients who received placebo (p <0.01). Quantitative assessment of LV opacification with videodensitometry showed similar results. The mean duration of clinically useful contrast was 90 seconds. Improvement in endocardial border delineation was demonstrated in 91% of patients who received perflutren and in 12% of those who received placebo (p <0.001). Following perflutren, an average of 4 more segments per patient were evaluable compared with baseline. Salvage of nondiagnostic baseline examinations by perflutren was demonstrated in 48% of eligible subjects. The safety profile of perflutren was similar to placebo. These data indicate that administration of perflutren to patients with suboptimal baseline images is well tolerated and provides substantial LV cavity opacification and improvement in endocardial border delineation.

Contrast echocardiography as an intraoperative method to determine the area of myocardium perfused by transmyocardial laser channels: an experimental study.

Transmyocardial laser revascularization (TMLR) of the ischemic myocardium has been recognized as a potentially useful adjunct in the treatment of coronary arterial heart disease. Although there are methods to visualize the induced channels, they have been complex or concerned with long-term patency. The present work was designed as a feasibility study to determine whether contrast echocardiography could provide a simple and rapid method to assist the surgeon in determining the extent of the TMLR-treated area. Transmyocardial channels were created in five Targhee adult sheep myocardium using a Holmium-YAG laser over the area supplied by the second diagonal branch. A commercially developed echocontrast agent (Optison) was injected into the left atrium. Passage of the dye through the myocardium was observed by epicardial echocardiography in all the animals. The current study shows that contrast echocardiography using a newer generation contrast agent capable of enhanced and persistent opacification of left ventricular cavity may serve as an effective tool in delineating intraoperatively the area of myocardium treated with TMLR.

Phase III multicenter trial comparing the efficacy of 2% dodecafluoropentane emulsion (EchoGen) and sonicated 5% human albumin (Albunex) as ultrasound contrast agents in patients with suboptimal echocardiograms

Objectives. This study was performed to compare the safety and efficacy of intravenous 2% dodecafluoropentane (DDFP) emulsion (EchoGen) with that of active control (sonicated human albumin [Albunex]) for left ventricular (LV) cavity opacification in adult patients with a suboptimal echocardiogram.Background. The development of new fluorocarbon-based echocardiographic contrast agents such as DDFP has allowed opacification of the left ventricle after peripheral venous injection. We hypothesized that DDFP was clinically superior to the Food and Drug Administration–approved active control.Methods. This was a Phase III, multicenter, single-blind, active controlled trial. Sequential intravenous injections of active control and DDFP were given 30 min apart to 254 patients with a suboptimal echocardiogram, defined as one in which the endocardial borders were not visible in at least two segments in either the apical two- or four-chamber views. Studies were interpreted in blinded manner by two readers and the investigators.Results. Full or intermediate LV cavity opacification was more frequently observed after DDFP than after active control (78% vs. 31% for reader A; 69% vs. 34% for reader B; 83% vs. 55% for the investigators, p < 0.0001). LV cavity opacification scores were higher with DDFP (2.0 to 2.5 vs. 1.1 to 1.5, p < 0.0001). Endocardial border delineation was improved by DDFP in 88% of patients versus 45% with active control (p < 0.001). Similar improvement was seen for duration of contrast effect, salvage of suboptimal echocardiograms, diagnostic confidence and potential to affect patient management. There was no difference between agents in the number of patients with adverse events attributed to the test agent (9% for DDFP vs. 6% for active control, p = 0.92).Conclusions. This Phase III multicenter trial demonstrates that DDFP is superior to sonicated human albumin for LV cavity opacification, endocardial border definition, duration of effect, salvage of suboptimal echocardiograms, diagnostic confidence and potential to influence patient management. The two agents had similar safety profiles.

Enhancement of Left Ventricular Cavity Opacification by Harmonic Imaging After Venous Injection of Albunex

Venous injection of Albunex does not consistently produce left ventricular (LV) cavity opacification during conventional echocardiography. We postulated that by increasing the signal-to-noise ratio, harmonic imaging will result in more successful LV cavity opacification and provide a better assessment of regional LV systolic function. Forty-two patients with poor baseline endocardial delineation were given 10 ml intravenous injections of Albunex during continuous fundamental and harmonic imaging. Change in segmental wall-thickening scores and the confidence levels for these scores were assessed for 3 observers with various levels of experience. Compared with fundamental imaging, harmonic imaging significantly improved the success of LV cavity opacification (83% vs 62%, p <0.05). The background-subtracted video intensity within the central two thirds of the LV cavity increased threefold (from 10 ± 15 to 31 ± 29, p <0.05) with harmonic imaging. The spatial extent of opacification increased from 40% of the LV cavity during fundamental imaging to 65% with harmonic imaging (p <0.001). The confidence level for assessing regional LV systolic function improved (p <0.05) after contrast administration, particularly when observer experience was limited. We conclude that in patients with poor endocardial definition, injection of intravenous Albunex should be combined with harmonic imaging to improve LV cavity opacification.We assessed left ventricular (LV) cavity opacification produced by venous injection of Albunex during fundamental and harmonic imaging in 42 patients. Harmonic imaging significantly increased the success rate of LV cavity opacification, the background-subtracted peak video intensity, and the spatial extent of cavity opacification; harmonic imaging also improved the confidence level for assessing regional LV systolic function, especially in readers with less experience.

Sonicated albumin in exercise echocardiography: Technique and feasibility to enhance endocardial visualization

Left ventricular cavity opacification can be produced by the intravenous injection of sonicated albumin (Albunex 422). A recent study suggested that sonicated albumin may be useful in dobutamine stress echocardiography, but its use in exercise echocardiography has not been reported. The purposes of the study were to assess the feasibility of using Albunex to enhance endocardial visualization and to evaluate the factors affecting Albunex kinetic in exercise echocardiography. Fifteen healthy volunteers underwent two exercise echocardiograms on the same day, with intravenous injection of Albunex during one of the studies. Two injections up to a maximum of 20 ml of Albunex per injection were given to enhance the four- and two-chamber views, both at rest and immediately after exercise. The degree of left ventricular enhancement and the percentages of endocardial visualization were measured in both resting and exercise images. Variables relating to the kinetics of Albunex, which included volume of contrast injected, transit time, heart rate, and cardiac output at the time of image acquisition, were also assessed. There was no difference in the image acquisition time between the two exercise echocardiograms. Albunex produced good left ventricular opacification both at rest and after exercise. More endocardial border was visualized with contrast injection than without (91.2% ± 11.5% vs 85.8% ± 14.2%, p = 0.007). The transit times and volumes of Albunex injected were significantly less after exercise than at rest. The parameters were inversely related to heart rate and cardiac output. In conclusion, intravenous injection of Albunex is a promising means to enhance left ventricular endocardial visualization in exercise echocardiography and can be readily incorporated without causing a significant delay in obtaining images after exercise. Whether its use can improve diagnostic accuracy of exercise echocardiography requires further studies.

Harmonic imaging dramatically enhances the success of left ventricular cavity opacification from venous injection of albunex R in patients : Jonathan Lindner, MD, John Dent, MD, Sally Moos, RDCS, Mary Nesbit, BSN, RN, RDCS, Sanjiv Kaul, MD. University of Virginia, Charlottesville, VA

Harmonic imaging dramatically enhances the success of left ventricular cavity opacification from venous injection of albunex R in patients : Jonathan Lindner, MD, John Dent, MD, Sally Moos, RDCS, Mary Nesbit, BSN, RN, RDCS, Sanjiv Kaul, MD. University of Virginia, Charlottesville, VA

Comparison of a new intravenous echo contrast agent (BY 963) with Albunex for opacification of left ventricular cavity.

Transpulmonary echo contrast agents improve the evaluation of left ventricular function by two-dimensional echocardiography due to a better endocardial border delineation. To compare the contrast effect in the right and left ventricular cavities, a new transpulmonary echocontrast agent, BY 963 and Albunex were intravenously administered to five non-anaesthetized dogs. The right and left ventricular echocardiographic image intensities were quantitatively measured at 60 cardiac cycles using a commercially available ultrasound system. BY 963 and Albunex were intravenously administered at three doses: 0.01 ml/Kg, 0.05 ml/Kg and 0.1 ml/Kg. The area under the curve (AUC, intensity units x heart cycles) and peak intensity (Peak I, intensity units) were estimated for the right (RV) and left ventricular (LV) cavities at the mid ventricular level using acoustic intensitometry. BY 963 injection produced the following values: At the dose of 0.01, 0.05 and 0.1 ml/Kg the AUC amounted to 702 +/- 449, 877 +/- 470 and 890 +/- 320 intensity units x heart cycles in RV and to 542 +/- 406, 806 +/- 557 and 721 +/- 392 in LV (LV/RV ratios: 77%, 92% and 81%). Peak I was at the doses 0.01, 0.05 and 0.1 ml/Kg 29 +/- 4.7, 33 +/- 5.2 and 35 +/- 3.2 intensity units in RV and 18 +/- 5.9, 21 +/- 6.2 and 20 +/- 3.3 in LV (LV/RV ratios: 62%, 64% and 57%). Albunex also produced right and left heart opacification values: at the doses 0.01, 0.05 and 0.1 ml/Kg the AUC amounted to 416 +/- 231, 493 +/- 231 and 674 +/- 390 in RV and to 71 +/- 71, 158 +/- 102 and 277 +/- 120 in LV (LV/RV ratios: 17%, 34% and 41%). Peak I was at the doses of 0.01, 0.05 and 0.1 ml/Kg 19 +/- 5.2, 23 +/- 5.4 and 29 +/- 4.1 in RV and 8 +/- 4.8, 13 +/- 4.7 and 17 +/- 3.2 in LV (LV/RV ratios: 42%, 57% and 59%). Intravenous injection of BY 963 leads to complete opacification of the left ventricular cavity and to high AUC values and peak intensity values at all three dosages. The loss of contrast effect from the right to the left ventricular cavity was very low: the LV/RV ratio of BY 963 was higher than that of Albunex. The new transpulmonary echo contrast agent BY 963 promises to be an excellent echo contrast agent for the noninvasive assessment of left ventricular function.

Myocardial contrast enhancement after intravenous injection of sonicated albumin microbubbles: a transesophageal echocardiography dipyridamole study.

Myocardial opacification after intravenous injection of an echo-contrast agent is a major end point in contrast echocardiography, but it has not yet been obtained in human beings. We propose transesophageal contrast echocardiography as a clinical tool for the study of myocardial perfusion in human beings. Sonicated albumin microbubbles are bright ultrasound reflectors that cross the pulmonary vasculature after intravenous injection and show physiologic transit times through tissues. Transesophageal echocardiography uses ideal transducer frequency and acoustic window for in vivo detection of sonicated albumin microbubbles. We have studied 11 patients receiving peripheral vein bolus injection of sonicated albumin microbubbles during transesophageal echocardiography at baseline and during dipyridamole infusion. Images were recorded on videotape and digitized off-line. Quantitative measurements were made on 11 normally perfused myocardial segments by tracing a region of interest of greater than 100 pixels on frozen end-systolic frames, at baseline, and during dipyridamole infusion. Transpulmonary passage with full left ventricular cavity opacification was obtained in all injections. In 8 of 22 injections there was also transient left ventricular cavity attenuation. In all patients there was a marked opacification of the left ventricular outflow tract and aortic root. At baseline, mean signal intensity in the myocardium increased from 80 +/- 37 to 117 +/- 49 IU (p < 0.05) and during dipyridamole infusion increased from 84 +/- 28 to 146 +/- 36 IU (p < 0.001). The analysis of background-subtracted data showed that mean pixel intensity increased from baseline to dipyridamole contrast injection (from 37 +/- 15 to 62 +/- 19 IU; p < 0.01). The opacification of normally perfused left ventricular myocardium is feasible during transesophageal echocardiography because there is a significant increase in signal intensity versus background intensity. During dipyridamole infusion there is a further increase in signal intensity that probably reflects pharmacologically induced increase in myocardial blood flow.

The influence of intravenous Albunex injections on pulmonary arterial pressure, gas exchange, and left ventricular peak intensity.

Contrast ultrasonography may be used to assess regional tissue perfusion. The purpose of this study was to evaluate the safety and efficacy of a new, commercially prepared ultrasound contrast agent (Albunex) in dogs. The injections were administered from peripheral intravenous (IV), right atrial (RA), and pulmonary artery (PA) sites. Acute pulmonary hemodynamic and gas exchange effects of low-dose (0.5, 1.0, 2.0 ml) Phase I injections, and high-dose (2.0, 5.0, 10, 20 ml) Phase II injections of Albunex were evaluated in nine dogs. Immediately before and after each injection, pulmonary artery pressure (PAP) and oxygen tension (PO2) were determined. In addition, left ventricular cavity opacification was assessed visually and by videodensitometric off-line analysis. Visual assessment was performed by four blinded observers who graded on a scale of 0 to 3 (0 = no contrast enhancement of the left ventricular (LV) cavity; 1 = weak or suboptimal contrast enhancement; 2 = optimal or excellent contrast enhancement; and 3 = attenuation of the ultrasound signal following a contrast injection). Peak pixel intensity was also determined with videodensitometric analysis. Results showed that significant changes in PAP or PO2 were not noted after Albunex injections, regardless of injection site or dose range. The average change in PAP after Albunex injection was 1.0 mm Hg +/- 1.2 mm Hg (NS), and the average change in PO2 after Albunex injections was 6.2 mm Hg +/- 6.7 mm Hg (NS). The left ventricular cavity peak pixel intensity was dependent on both injection site (PA = RA > IV) and dose range (2.0 = 1.0 > 0.5).(ABSTRACT TRUNCATED AT 250 WORDS)