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PubMed2000

Transesophageal echocardiographic assessment of hemodynamic function during laparoscopic cholecystectomy in healthy patients.

BACKGROUND: This study aimed by means of transesophageal echocardiography, to evaluate hemodynamic changes induced by pneumoperitoneum in patients with normal cardiac performance. METHODS: In this study, 11 ASA I-II patients (mean age, 39 years) with normal cardiac performance undergoing laparoscopic cholecystectomy were evaluated. A 5-MHz transesophageal biplane phased-array transducer connected to an echocardiographer was inserted after induction of anesthesia. Data were collected at three different times: before insufflation (T1), 10 min after insufflation (T2), and 5 min after desufflation (T3). At these same times, heart rate, systolic blood pressure, diastolic blood pressure, end-tidal carbon dioxide (CO(2)), and peak airway pressure were recorded. Statistical analysis was performed using one-way and two-way analysis of variance (ANOVA). A p value less than 0.05 was considered significant. RESULTS: End-systolic and end-diastolic diameters of the left ventricle, contractility, and performance parameters did not change significantly. Conversely, at insufflation, color Doppler area of the mitral backflow increased significantly (p < 0.05) when already present or showed up abruptly (T1: 0.22 +/- 0.28 cm(2); T2: 1.28 +/- 1.02 cm(2); T3: 0.49 +/- 0.53 cm(2)). CONCLUSIONS: Such an event is not interpreted as a mitral insufficiency. It is possibly the result of a "contrast effect" caused by the absorption of CO(2) microbubbles in the blood.

Adult↗

PubMed2006

The extent of right-to-left shunt fails to correlate with severity of clinical picture in migraine with aura.

Several investigations have documented an increased incidence of right-to-left shunt (RLS) in migraine with aura (MA) and have emphasised its role in the physiopathology of aura; so far, however, no data are available concerning a possible correlation between the extent of the RLS and the clinical picture of MA patients. To investigate the possible relationship between the extent of the RLS, revealed by the number of microbubbles (MB) detected during transcranial Doppler with IV injection of ultrasound contrast (TCDc), and the clinical characteristics of MA (age at first onset of migraine, mean annual frequency of attacks and mean duration of the aura phase), 30 consecutive patients with typical aura and migraine headache positive on TCDc evaluation for RLS were enrolled. Permanent RLS was found in 12 patients and latent RLS was found in 18 patients; of these, 6 had a high-grade RLS, 5 medium-grade RLS and 7 low-grade RLS. No correlation has been documented between the number of MBs and the clinical parameters of both patients with latent shunts and those with permanent ones, nor between the clinical parameters of the two groups of patients. These data show that RLS does not seem to affect the clinical manifestation of MA and that the extent of RLS fails to correlate with the severity of the clinical picture of the disorder.

Adult↗

PubMed2004

Real-time, contrast-specific sonography imaging of acute splenic disorders: a pictorial review.

Real-time, contrast-specific ultrasonography (US) uses low-mechanical-index, harmonic software to stimulate echo emission from resounding second-generation contrast medium microbubbles. At our institution, contrast-enhanced US is increasingly being used in the evaluation of acute abnormalities of the spleen, mainly to overcome some limitations of conventional (basic) US. This pictorial essay illustrates the appearance of several acute splenic lesions, both traumatic and nontraumatic, on contrast-specific US.

Acute Disease↗

PubMed2006

Recent applications of ultrasound: diagnosis and treatment of hepatocellular carcinoma.

Ultrasound (US) has the advantages of real-time observation, simple technique, and a noninvasive procedure compared to other imaging modalities. The recent development of digital technologies has enabled the observation of sonograms with improved signal-to-noise ratio, penetration, and spatial and contrast resolutions. Furthermore, microbubble contrast agents have increased the diagnostic ability of US examination, and the use of three-dimensional sonograms is now not unusual. These advances have furthered the usefulness of US for liver tumors in clinical practice. This article reviews the recent applications of US in the diagnosis and treatment of hepatocellular carcinoma.

Carcinoma, Hepatocellular↗

PubMed2006

Gene therapy targeting kidney diseases: routes and vehicles.

Renal gene therapy may offer new strategies to treat diseases of native and transplanted kidneys. Several experimental techniques have been developed and employed using nonviral, viral, and cellular vectors. The most efficient viral vector for in vivo transfection appears to be adenovirus. In addition, enhanced naked plasmid techniques, such as the hemagglutinating virus of Japan (HVJ)-liposome method, electroporation, the hydrodynamic method, and ultrasound with microbubbles, are promising. Trapping genetically modified macrophages in the inflamed kidneys is an elegant method for site-specific gene delivery. The choice of delivery vehicle as well as the administration route determines the site of transduction. In conclusion, for both in vivo and ex vivo renal transfection, enhanced naked plasmids, adenoviruses, and modified cell vectors offer the best prospects for effective clinical application. Moreover, the development of safer and nonimmunogenic vectors may realize clinical renal gene therapy in the near future.

Adenoviridae↗

PubMed2005

Vasa vasorum imaging: a new window to the clinical detection of vulnerable atherosclerotic plaques.

Complications of vulnerable atherosclerotic plaques (rupture, luminal and mural thrombosis, intraplaque hemorrhage, rapid progression to stenosis, spasm, and so forth) lead to heart attacks and strokes. It remains difficult to identify what plaques are vulnerable to these complications. Despite recent developments such as thermography, spectroscopy, and magnetic resonance imaging, none of them is approved for clinical use. Intravascular ultrasound (IVUS), a relatively old yet widely available clinical tool for guiding intracoronary procedures, is increasingly used for characterization of atherosclerotic plaques. However, inability of IVUS in measuring plaque activity limits its value in detection of vulnerable plaques. In this review, we present new information suggesting that microbubble contrast-enhanced IVUS can measure activity and inflammation within atherosclerotic plaques by imaging vasa vasorum density. An increasing body of evidence indicates that vasa vasorum density may be a strong marker for plaque vulnerability. We suggest that a combination of structural assessment (cap thickness, lipid core, calcification, etc) and vasa vasorum density imaging by IVUS can serve as the most powerful clinically available tool for characterization of vulnerable plaques. Due to space limitations, all IVUS images and movies are posted on the website of the Ultimate IVUS Collaborative Project: http://www.ultimateivus.com.

Albumins↗

PubMed2001

How to improve prostate biopsy detection of prostate cancer.

The combination of serum prostate-specific antigen (PSA) testing and transrectal ultrasonography is a highly effective strategy to diagnose prostate cancer at an early curable stage. Even though PSA is the most useful serum biomarker to aid in prostate cancer detection, it has limited specificity: as many as 75% of men who undergo prostate biopsy because of an elevated PSA do not have prostate cancer. Additionally, sextant prostate biopsies miss prostate cancer at least 20% of the time. To reduce the number of false-negative biopsies, many have advocated obtaining 12 or more cores in a single biopsy session. Studies have shown that this practice is safe and can enhance cancer detection modestly. Although it is unlikely that prostate cancer imaging will replace prostate biopsy in the near future, many exciting new imaging technologies should eventually improve targeting of prostate needle biopsy and reduce false-negative biopsies. Some of the most exciting areas include power Doppler sonography, microbubble intravenous ultrasound contrast agents, and magnetic resonance spectroscopy. These functional imaging modalities can assess tumor blood flow and metabolic activity at a cellular level and can detect malignant changes that may not be detected by standard anatomic imaging.

Biopsy, Needle↗

PubMed1983

Phasic pressure gradients across coronary and renal artery stenoses in humans.

Fluid-filled catheter-transducer systems have been developed for assessment of phasic pressure gradients across arterial stenoses. The two catheters we have employed are 3 French and 2 French in diameter. After the catheters are flushed with carbon dioxide and filled with degassed saline solution to remove microbubbles of air, the catheters are attached to a low-volume displacement transducer. The frequency response of both catheter-transducer systems is adequate to record phasic arterial pressures. The catheters are very flexible and radioopaque, and the ability to monitor phasic pressure continuously at the tip during passage across a stenosis enhances safety of their use. The catheters have been employed successfully to measure phasic pressure gradients across 36 coronary and five renal artery stenoses. Maximal pressure gradients were observed in early diastole for coronary stenoses and in systole for renal artery stenoses, consistent with known differences in phasic flow patterns in these vascular beds. The pressure gradients in patients with coronary stenoses could be markedly increased by injection of contrast medium (Renograffin 76). Relatively poor correlation was observed between the resting pressure gradients and the angiographically defined degree of coronary stenoses.

Adolescent↗

PubMed1985

Spontaneous echographic contrast in the inferior vena cava.

The inferior vena cava was examined for spontaneous contrast by two-dimensional echocardiography in 106 consecutive patients. Images of the inferior vena cava in six patients were inadequate and were excluded from further analysis. The study population included 100 patients, 41 men and 59 women. Twenty-three patients had an intravenous line or heparin lock in place at the time of the echocardiographic examination. Ten patients had definite contrast in the inferior vena cava, seven had equivocal contrast, and 83 had no contrast. The three groups did not differ significantly with respect to sex distribution, age, associated diagnoses, or inferior vena cava dimension. We concluded that spontaneous inferior vena cava contrast is commonly seen in adults, both normal subjects and patients with various types of heart disease. There was no specific category of heart disease that predominated in patients with spontaneous inferior vena cava contrast. Although it may be associated with impairment to filling of the right side of the heart and may resolve when normal right heart hemodynamics are restored, spontaneous inferior vena cava contrast is usually a finding with little clinical import. Several possible etiologic factors include microbubbles and aggregates of formed blood elements. Spontaneous inferior vena cava contrast is seen more frequently with a higher frequency imaging system.

Adolescent↗

PubMed1994

Assessment of regional myocardial perfusion with myocardial contrast echocardiography in a canine model of varying degrees of coronary stenosis.

Previous studies showed that myocardial contrast echocardiography can be used to detect relative regional underperfusion in a canine model of critical coronary stenoses. The aim of this study was to determine if myocardial contrast echocardiography performed with a sterile sonicated human serum albumin preparation (Albunex, Molecular Biosystems, San Diego, Calif.) could detect the presence of coronary stenoses of variable degrees of severity. The results were compared with myocardial blood flow as assessed by radiolabeled microspheres in 16 open-chest dogs during baseline, following the creation of a coronary stenosis of variable severity and at the peak of dipyridamole-induced hyperemia. When flow ratios (that is, flow in the control area/ischemic area) were examined, a good correlation was observed between the area under the time-intensity curve and radioactive microsphere blood flow (r = 0.94, p < 0.0001), which allowed distinction of mild from severe stenosis. However, a consistent underestimation of the dipyridamole-induced hyperemia by myocardial contrast echo was seen in the control zone. This could be partially explained by a simultaneous increase in coronary blood flow and blood volume with dipyridamole and by attenuation of the ultrasound signal because of the high concentration of microbubbles at high flows. Myocardial contrast echocardiography can quantitate the amount of jeopardized myocardium during various degrees of coronary stenoses.

Animals↗

PubMed1983

Hydrogen peroxide contrast echocardiography.

Several agents are used as echocardiographic contrast agents, but their unreliability discourages routine clinical use. Studies from the early 1960s suggest that dilute hydrogen peroxide (H2O2) is a safe intravascular agent. Its use was evaluated in contrast echocardiography. To obtain dense opacification reliably, H2O2 (3%) was passed through a sterile 0.2 micron Millipore filter and diluted with heparinized saline solution to make a 0.1 to 0.2% solution. A drop of blood was withdrawn from an indwelling peripheral venous needle into a syringe containing 0.5 to 2.0 ml of the dilute H2O2 and the contents injected. Studies in dogs, normal adults and 36 patients with noncyanotic congenital and acquired cardiac disorders produced dense opacification with no complications. In vitro mixture of H2O2 (0.3%) with leukocyte-poor blood or plasma produced only a few microbubbles, while addition to whole blood or buffy coat produced many, suggesting a role for leukocyte peroxidase. H2O2 contrast echocardiography is simple, inexpensive, and reliably provides dense, sustained opacification. This study and previous studies suggest that intravenous injection of 0.2% H2O2 can be done safely. Great caution should be exercised in patients with severe pulmonary hypertension or large right-to-left shunts because little clinical experience with H2O2 is available.

Animals↗

PubMed1983

Application of 2-dimensional contrast studies during pericardiocentesis.

Two-dimensional echocardiographic contrast studies were performed in 16 patients with pericardial effusion. A 4-chamber view was obtained by positioning the transducer at the apex. The exploratory needle was visualized in 9 patients. Five milliliters of saline solution were injected through the exploring needle and a cloud of echoes indicated its position. Microbubbles were seen in all 16 patients. This technique enabled the operator to identify that the needle was inadvertently in the left ventricle in 2 patients and in the right ventricle in 1. Furthermore, in 2 patients, when fluid could not be aspirated, the contrast study confirmed that the needle was in the pericardial sac; in both cases, pericardial fluid could be aspirated with slight manipulation of the needle. In a patient with a stab wound a negative contrast effect indicated the probable site of laceration. Thus, 2-dimensional contrast echocardiography was useful in locating needle position, which facilitated pericardiocentesis.

Adult↗

PubMed1985

Usefulness of transstenotic coronary pressure gradient measurements during diagnostic catheterization.

A difficult problem in coronary arteriography is the assessment of the hemodynamic significance of stenoses that appear angiographically to be of only moderate severity (25 to 75% diameter narrowing). This is particularly important in patients who may be candidates for invasive therapy, such as percutaneous transluminal coronary angioplasty (PTCA) or coronary bypass surgery. To determine the significance of such lesions, we measured transstenotic coronary pressure gradients in 15 patients with angiographically moderate stenoses. For comparison, similar measurements were made in 17 patients with severe stenoses (more than 75% diameter narrowing) being considered for PTCA. The transstenotic pressure gradients were measured with a 2.0Fr polyvinyl chloride catheter cleared of microbubbles of air by flushing with carbon dioxide and degassed saline solution and attached to a low-volume displacement transducer for optimal frequency response. Mean transstenotic pressure gradients greater than 10 mm Hg at rest or more than 20 mm Hg under conditions of high coronary blood flow, as induced by Renografin 76, appeared to be associated with objective evidence of myocardial ischemia and symptomatic relief from PTCA. Smaller pressure gradients occurred in patients whose symptoms probably were not ischemic in nature. Transstenotic pressure gradient determination performed at the time of diagnostic catheterization may provide assistance in clinical decision-making in selected patients with angiographically moderate stenoses.

Angioplasty, Balloon↗

PubMed1989

Improved sensitivity of color Doppler by SH U 454.

SH U 454, a suspension of galactose microparticles, provides microbubbles (97% less than 7 microns) in variable, reproducible concentrations. Its influence on color Doppler imaging was evaluated in a flow model study and in a clinical study. In the flow model, increasing attenuation (up to 11.4 dB/MHz) impaired the signal to noise ratio and decreased the sensitivity for detecting flow velocities. Thus, flow signals were obtained with flow velocities greater than 3 cm/s (0.1 dB/MHz), greater than 9 cm/s (5.7 dB/MHz) and greater than 17 cm/s (11.4 dB/MHz). After injection of SH U 454 (200 mg/ml), velocities down to 3 cm/s were detected even with high attenuation (11.4 dB/MHz). Color Doppler imaging was performed before and after intravenous injection of 2 ml, 3 ml and 4 ml of SH U 454 (200 mg/ml) in 22 adult patients, and the maximal color-coded areas of diastolic blood flow were determined in the right atrium and ventricle. In 19 of 22 patients, the displayed color-coded areas increased after injection of SH U 454. The diastolic blood flow was imaged on 14 +/- 8% (mean +/- 1 standard deviation) of the cross-sectional area of the right ventricle (4-chamber view) without SH U 454, compared with 39 +/- 15% with 3 ml of SH U 454 (p less than 0.001). For the right atrium, the area displayed by color Doppler increased from 9 +/- 13 to 62 +/- 25% (p less than 0.001). The variability of the measurements from patient to patient after injection of SH U 454 was 5.9 +/- 4% as compared with 10.7 +/- 6.9% without SH U 454 (p less than 0.05). These findings indicate that the intravenous injection of SH U 454 increases the sensitivity of color Doppler imaging for detection of blood flow by improving the signal to noise ratio.

Adult↗

PubMed1992

Sonicated serum albumin in contrast echocardiography: improved segmental wall motion depiction and implications for stress echocardiography.

We undertook to study the ability of intravenously administered sonicated albumin microbubbles to opacify the left ventricular (LV) cavity, enhance endocardial delineation, and thereby improve the interpreter's confidence in evaluating regional wall motion in patients whose baseline echocardiograms were believed to be technically difficult because of limited endocardial resolution. We studied 30 adult patients with endocardial border dropout of greater than or equal to 20% on routine echocardiography. Efficacy was evaluated by the investigator and 2 blinded observers using an opacification grading system of 0 (no appearance in LV cavity) to 3+ (full LV chamber opacification). Effective opacification was indicated by a score of greater than or equal to 2+. Border delineation improvement equaled a change from grade A (not well delineated) to grade B, C, or D (well delineated) of at least 1 of 6 LV wall segments. Initially all patients received a 0.08 mL/kg injection. The patient received 2 additional injections of 0.14 and 0.08 mL/kg given 5 minutes apart if the initial volume produced at least 2+ LV opacification. Otherwise, a final injection of 0.22 mL/kg was given. In all cases, the patients' arms were raised after injection to enhance venous passage. When graded by the investigator, 29 patients (97%) exhibited greater than or equal to 2+ opacification. When graded by the blinded observers, 27 patients (90%) exhibited greater than or equal to 2+ opacification. Improved border delineation was noted by the investigator in 90% of patients, and the blinded observers noted improvement in 97% (excluding 1 patient who, if scored by a blinded observer, would have received a higher dose of contrast agents).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Clinical applications of myocardial contrast echocardiography.

Myocardial contrast echocardiography is a new technique that uses microbubbles of air in conjunction with simultaneously performed 2-dimensional echocardiographic imaging. Currently, it can be used to determine myocardial perfusion in the cardiac catheterization laboratory and the operating room. For myocardial contrast echocardiography to find a broader clinical application for the assessment of myocardial perfusion, it will be necessary to opacify the myocardium from venous injection of contrast in humans. In this regard, enhancement in bubble engineering, optimization of echocardiographic systems (greater sensitivity and dynamic range), and availability of digital image enhancement techniques will be required for myocardial contrast echocardiography to realize its full clinical potential by the year 2000.

Coronary Disease↗

PubMed1988

Ultrasonic wave fluctuations through tissue: an experimental pilot study.

The fundamental role of the assumption of plane wave ultrasonic propagation in attenuation and scattering measurements on soft tissues is discussed. The evidence for and against the validity of the assumption is shown to be inconclusive. An experimental procedure for direct assessment, by measurement of the ultrasonic amplitude and phase fluctuations occurring after an interrogating plane wave has passed through a tissue specimen, is described. The phase measurements impose significant demands on the mechanical precision, temperature stability and electronic timing capabilities of the measurement system. Measurements are reported on two specimens of fresh beef liver. One exhibited significant fluctuations of amplitude and phase which were reduced by 50% when the effects of thickness variations in the specimen were removed. The other specimen exhibited relatively small fluctuations. The feasibility of making such measurements has been demonstrated and the detailed features of the experimental procedure-which requires considerable care-have been outlined. Although more measurements are needed for definitive conclusions, these will require the development of a reliable technique for determining the presence of gaseous microbubbles in tissue in vitro. The preliminary conclusion that some samples of liver may exhibit low levels of wavefront disruption is consistent with recent evidence in the literature.

Animals↗

PubMed1990

Some of the factors involved in the Sarvazyan method for recording ultrasound field distributions with special reference to the application of ultrasound in physiotherapy.

The mapping of ultrasound fields using the dye paper method is described. The mode of action by which the dye concentration is increased has been investigated. Microbubbles on the paper surface and microstreaming of dye solution seem to be essential features of the mapping method. The streaming is thought to inhibit the formation of a dye depletion layer near the paper to an extent dependent on local sound intensity A linear relation between streaming velocity and intensity is derived.

Coloring Agents↗