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PubMed2003

Myocardial contrast echocardiography for the assessment of left ventricular function.

Assessment of regional and global left ventricular (LV) function is important in the management of patients with known or suspected cardiovascular disease. Echocardiography is widely used to provide vital parameters of LV function such as ejection fraction, wall motion score indices, LV volumes and regional wall motion assessment. Despite advances in image quality some images may still be inadequate for accurate assessment of LV function. The advent of intravenous contrast agents consisting of microbubbles have allowed improved endocardial definition leading to better assessment of global and regional function. This together with advances in low power imaging techniques allow less microbubble destruction and hence smaller doses of contrast agent. Improved endocardial definition has also lead to advances in techniques for the automated quantification of LV function. As a result contrast enhanced echocardiography may become the gold-standard in the assessment of wall motion and LV function.

Contrast Media↗

PubMed2003

[Detection modes of ultrasound contrast agents].

Ultrasound contrast agents have been used for many many years in cardiology. Their application in other fields is more recent, related to the availability of agents that can pass through the pulmonary circulation. Physical properties of contrast microbubbles are closely bound to their gas content, shell composition, frequency of ultrasound beam, pulse repetition frequency, acoustic power and wave phase. Specific ultrasound sequences have to be used to adequately exploit microbubble-specific interactions with the ultrasound beam. The aim of this paper is to review physical properties of ultrasound contrast agents, present imaging sequences developed for optimal use of these contrasts and general applications.

Artifacts↗

PubMed2003

[Contrast ultrasound imaging in liver disease].

The recent introduction of high-end ultrasound equipments combined with the introduction of contrast agents provides marked improvements in liver imaging for the detection and the characterization of focal lesions. Previous imaging methods were based on high acoustic power and demonstrated improved detection of focal liver lesions. However, good and reliable results were difficult to achieve due to limited number of sweeps, as most of the microbubbles were destroyed within one pass. Non linear imaging methods at low acoustic power allowed great advances in the characterization by limiting signal from background tissue as well as agent collapse allowing continuous imaging starting from the time of contrast injection until complete disappearance of the agent. Contrast-enhanced imaging of the liver follows conventional sonography performed with high standards for detection and localization of lesions using multiple sweeps. Then targeted acquisition is performed for specific lesion characterization after a second contrast injection. Interpretation is based on the presence or not of microbubbles within the lesion (hyper-, hypo- or isosignal) and the delay from injection (arterial, portal or parenchymal or late phase). A well-recognized semiology is reported in this paper. Based on these criteria, sensitivity and specificity are close to those reported with other modalities with accuracy 85-95% for focal liver lesions and 75% for hepatocellular carcinomas. Those results markedly improve ultrasound accuracy compared to conventional sonography, and so put contrast-enhanced sonography among recommended non-invasive imaging methods for focal liver lesions with changes in diagnostic strategy.

Aged↗

PubMed2006

Can the carpometacarpal joint be injected accurately in the office setting? Implications for therapy.

OBJECTIVE: To investigate whether carpometacarpal (CMC) injections can be performed accurately in the office setting in patients with moderate to severe CMC osteoarthritis (OA). METHODS: Patients were recruited from rheumatology and hand surgical practices as part of an open label trial of hylan G-F 20 for CMC OA. CMC injections were performed without radiologic guidance, using anatomic landmarks to guide needle placement. Once injected, the patient was immediately taken to an adjacent ultrasound suite, and the injected CMC joint examined for evidence of intraarticular material and air microbubbles. RESULTS: Thirty-two patients were injected. All patients had ultrasound evidence of intraarticular material: 91% also had evidence of microbubbles in the joint. CONCLUSION: CMC injections can be performed accurately in the office setting, without the need for radiologic guidance, in patients with moderate to severe CMC OA.

Adjuvants, Immunologic↗

PubMed2006

[Protective and curative effects of prophylactic administration of pulmonary surfactant on neonatal respiratory distress syndrome].

OBJECTIVE: To evaluate the protective and curative effects of prophylactic administration of pulmonary surfactant (PS) on neonatal respiratory distress syndrome (NRDS). METHODS: One hundred neonates aged 0.5 h after birth, with the gestational age < 32 w, birth weight < 1500 g, and number of gastric, stable microbubble < or = 7/mm(2) by gastric stable microbubble test (SMT), but without clinical or radiological manifestations of RDS at the admission, were randomly divided into 2 equal groups: prophylactic group (PG), receiving curosurf, a product of PS, immediately after admission; and non-prophylactic group (N-PG), receiving curosurf only after development of RDS. RESULTS: One hour after the administration of PS, the PaO(2), a/APO(2), pH, and PaO(2) of the PG group were 86.2 mm Hg +/- 8.1 mm Hg, 0.30 +/- 0.04, 7.38 +/- 0.06, and 178 +/- 37, all significantly higher than those of the non-PG group (all P < 0.01), and the PaCO(2) of the PG group was 37.3 mm Hg +/- 9.8 mm Hg, significantly lower than that of the non-PG group (53.6 mm Hg +/- 11.1 mm Hg, P < 0.01). In comparison with the level before the administration of PS (0.75 +/- 0.06), the level of FiO(2) of the 47 pediatric patients receiving mechanical ventilation decreased after the administration of curosurf time-dependently, e.g., was 0.50 +/- 0.09, 0.34 +/- 0.06, and 0.25 +/- 0.07 8, 48, and 96 hours after the administration. In comparison with the level before the administration of curosurf 9.0 +/- 1.0 cm H2O, the level of mean airway pressure (MAP) decreased time-dependently after the administration, e.g., were 7.5 +/- 0.8 and 6.0 +/- 0.3 48 and 96 hours after the administration (all P < 0.01). Compared with that before the administration of curosurf (3.02 +/- 0.2), the X-ray chest score decreased time-dependently after the administration of curosurf, e.g., were 1.89 +/- 0.34, 1.82 +/- 0.33, and 1.17 +/- 0.42 6, 12, and 72 hours after the administration (all P < 0.01). The RDS rate of the PG group was 30%, significantly lower than that of the non-PG group (P < 0.01). The severe case rate of the PG group was 20%, significantly lower than that of the N-PG group (53%, P = 0.01). The mortally of the PG group was 0, significantly lower than that of the non-PG group (P < 0.05). The total times of supplemental oxygen administration, assisted ventilation and hospitalization of the 47 patients with RDS in the PG group were significantly shortened compared with the RDS patients in the N-PG group [(3.6 +/- 1.7) d vs. (5.9 +/- 3.6) d, P < 0.05; (8.6 +/- 5.5 d vs. (14.1 +/- 6.2) d, P < 0.01; and (20.5 +/- 10.0) d vs. (32.8 +/- 17.8) d, P < 0.05). CONCLUSION: Prophylactic administration of PS to the preterm neonates with high risk of RDS effectively decreases the incidence of RDS, development of severe cases and mortality, shorten the disease course, the duration of supplemental oxygen administration and assisted ventilation, thus decreasing the potential morbidity associated with long-term oxygen supplement and assisted ventilation.

Biological Products↗

PubMed2006

[Place of contrast imaging in prostate cancer detection].

Contrast imaging of the prostate is based on rapid-sequence MRI after dynamic Gadolinium injection and contrast ultrasound after injection of microbubbles. MRI can be performed routinely on all available machines. Contrast ultrasound requires specific software not yet available on all machines. The two techniques are designed to improve the reliability of imaging, as a complement to MR spectroscopy, to localize prostate cancer MRI can detect suspicious enhancement in the peripheral zone, but especially in the transitional zone after one or a series of negative posterior biopsies to target a new series of biopsies. The sensitivity and specificity of the technique have yet to be determined. The objective of contrast ultrasound is to improve cancer detection on the first series of biopsies by multiplying sextant biopsies in sites where the contrast kinetics are suggestive of a primary lesion. However, this technique cannot yet be recommended in routine practice, as the modalities of injection of the latest generation of microbubbles (bolus or infusion) need to be evaluated.

Contrast Media↗

PubMed1991

Cytotoxic effects of acoustic cavitation on HT-29 cells and a rat peritoneal carcinomatosis in vitro.

Damage to cells and tissues exposed to shock waves (SWs) is thought to be secondary to cavitation phenomena involving the collapse of gas bubbles in a fluid. Using HT-29 cells and DHDK12PROb tumors, we tried to enhance SW-related damage by the simultaneous administration of gas microbubbles. Bubbles resulted from a mixture of air and gelatin (HT-29 cells) or from a carbonated NaCl solution (tumors). HT-29 cells in suspension received either SW (50, 250, or 1000 SWs) alone or in association with bubbles. Trypan blue-negative cells decreased as the number of SWs increased. Exposure to SWs and bubbles resulted in not only an increased but also a delayed mortality as compared to SWs only. One thousand SWs with bubbles induced a complete inhibition of cell growth, with cytoplasmic vacuolae, ruptured membranes, and abnormal nuclear shape and chromatin. Exponential and confluent cells exhibited a similar mortality and growth. DHDK12PROb tumors received either SWs only (50, 100, 250, 500, or 1000 SWs) or SWs with bubbles in vitro. Thymidine incorporation was significantly lower after exposure to SWs with bubbles as compared with controls and SWs only; it was nil by 1000 SWs with bubbles. Histopathological features of tumors exposed to SWs with bubbles included erosion and hemorrhage, disorganized structure, pyknotic nuclei, and cytoplasmic vacuolae. We conclude that cavitation, as produced by a combination of SWs and gas microbubbles, can achieve bioeffects which are relevant to cancer therapy.

Animals↗

PubMed1989

[Contrast-color Doppler echocardiography. Improved right heart diagnosis following intravenous injection of Echovist].

Flow patterns in the right heart are often difficult to visualize by color-coded Doppler flow imaging. The echogenicity of blood was increased in 48 patients by intravenous injection of 10 ml echovist (200 mg/ml), a saccharide solution with defined size and concentration of microbubbles. Its effect on improving color-coding was compared with the effect of agitated gelifundol (10 ml) in 21 patients with tricuspid valve regurgitation. The non-controlled size and concentration of microbubbles resulted in weaker or uncontrollably exaggerated color-coding in half of the patients. In eight normals biphasic atrial flow was visible only after injection of echovist. In 25 patients with tricuspid regurgitation the blue coded area of reflux was 25 +/- 21% of the atrial area from the parasternal approach and 10 +/- 9% from the apical approach without correlation of these results. After echovist the area of reflux was 57 +/- 31% (p less than 0.001) in the parasternal and 53 +/- 26% (p less than 0.001) in the apical approach (r = 0.83). This was paralleled by an increase of the severity of tricuspid regurgitation as defined by the length or area of reflux (p less than 0.01-0.001). The qualitative diagnosis was safely established in the five patients with VSD in the control color Doppler flow imaging, but only in three out of 10 patients with ASD, and in nine of 10 after injection of echovist. The intravenous injection of echovist, when using color-coded Doppler flow imaging for evaluation of right heart disease, facilitates the qualitative diagnosis of ASD and also of tricuspid regurgitation, particularly in the apical approach.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Myocardial contrast echocardiography: a new method for the evaluation of regional myocardial blood flow.

Myocardial contrast echocardiography is a new method enabling detailed evaluation of blood flow distribution within the myocardium. It is performed by means of intracoronary injection of small volumes of carrier solutions containing small microbubbles of a size similar to that of red blood cells. The perfused myocardium opacifies densely, while the ultrasonic backscatter of nonperfused areas does not change. This method enables evaluation of the physiologic impact of coronary stenosis, diagnosis of "small vessel disease", collateral blood flow assessment, infarct size measurement and, with the help of videomemory and a computer, also regional myocardial blood quantification. This paper reviews all hitherto published studies with myocardial contrast echocardiography in humans including some studies only recently submitted for publication. These studies examined a total of 169 patients. No complications of intracoronary injection of microbubbles were described. Transient ECG and haemodynamic changes of less than 30 seconds' duration are less pronounced than during routine coronary arteriography. This paper describes the methodology, safety, physiology and potential clinical usefulness of myocardial contrast echocardiography.

Contrast Media↗

PubMed1986

[Contrast echocardiography in the diagnosis of tricuspid insufficiency. Evaluation before and after cardiosurgical intervention in 24 patients].

26 patients (pts) (8 males and 18 females), mean age 50 +/- 9 years, with rheumatic valve (MV) disease, candidates to MV replacement, were examined by contrast echocardiography (CE) before and after surgery. This was done in order to assess pre and postoperatively the presence of associated tricuspid regurgitation (TR) and to evaluate the short and long-term results of the operation on the TR itself. For assessing TR, the systolic presence, intensity and persistence of the microbubbles of the contrast medium injected into an antecubital vein, were observed within the inferior vena cava (IVC). We used synchronous time motion (TM) and two dimensional (2D) echocardiography from subcostal view. TR was classified as follows: severe (massive systolic opacification and persistence of the microbubbles in the IVC for at least 20 seconds); moderate (moderate systolic opacification lasting less than 20 seconds); mild (slight systolic opacification lasting less than 10 seconds); insignificant TR (sporadic appearance of the contrast medium into the IVC). On the average, the examination was carried out 48 hours before surgery, 15 days after and, in pts undergoing De Vega tricuspid valvuloplasty, 14 months after the operation. At pre-operative examination, massive TR was found in 16 pts, only 6 of whom showed clinical signs of TR. The findings were confirmed at surgery in 15 pts who underwent not only MV replacement but also tricuspid repair. In the other pts, agreement was found between CE and surgery as far as moderate TR was concerned, meanwhile mild CE TR was not confirmed at surgery. Sensitivity (SN) was 100%, specificity (SP) 38%, positive predictive value (PPV) 78%, negative predictive value (NPV) 100%. Excluding CE mild TR, SP and PPV raised to 75% and 95% respectively, meanwhile SN and NPV remained 100%. Short term post-operative follow-up CE performed on 13 out of the 15 pts with tricuspid repair showed no signs of TR in 7 and slight signs in 6. Furthermore, in those pts undergoing simple MV replacement, CE showed a marked reduction of the contrast echographic effect. Long term post-operative follow-up CE performed in the 13 pts with tricuspid repair showed no signs of TR in 9, slight signs in 3. Moreover in two pts massive TR due to late mitral prosthesis detachment was diagnosed by means of CE and confirmed at cardiac catheterization and surgery.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1984

[Prevention of gas microemboli during cardiac surgery. Numerical control of cardiac cavity purging by an ultrasonic detector].

Despite all precautions taken by cardiac surgeons to eliminate air remaining in the cardiac cavities and pulmonary veins at the end of cardiopulmonary bypass, many micro bubbles probably remain and pass into the systemic circulation with a risk of deteriorations of cerebral or myocardial function. Over the last four years we have used ultrasound to try to prevent the risk of preoperative gas microemboli: the machine is equipped with a detector (a quartz oscillator coupled to a piezoelectric transducer emitting a continuous beam of ultrasound at a frequency of 5 Mhz) which allows the following variables to be determined: the time interval from the onset of detection, the total quantity of bubbles (arbitrary units) in the examined regions, the quantity of bubbles detected over a given time interval which can be adjusted from 15 to 120 seconds. The passage of bubbles is also indicated by light and sound alarms. The smallest diameter of bubbles which can be detected is about 10 mu. There are periaortic probes adaptable to the calibre of the ascending aorta, transcutaneous probes for carotid artery detection and a left ventricular probe. In a preliminary series of 74 valve replacements in adults, this apparatus was used immediately after terminating cardiopulmonary bypass after we had thought that the cardiac cavities had been satisfactorily purged of air, and whilst active aspiration was continued in the ascending aorta distal to the periaortic probe: the total quantity of bubbles detected varied from less than 50 to more than 2000 AU, over a variable period of time which may exceed 20 min after termination of cardiopulmonary bypass. The total quantity of bubbles recorded after mitral valve (582 +/- 154 AU) or combined mitral and aortic valve replacement (685 +/- 167 AU) was generally greater than after isolated aortic valve replacement (335 +/- 126 AU). Therefore, after cardiopulmonary bypass, and despite all efforts at purging the air, we showed that numbers of microbubbles were ejected into the ascending aorta for a variable period of time: only some of them were eliminated by active aspiration through a trocar placed distal to the periaortic probe. The right coronary ostium was poorly protected against microbubbles because of its anatomical situation (6 cases in this series). We therefore established a protocol for the use of this apparatus to aid the purging of the cardiac cavities and pulmonary veins before stopping cardiopulmonary bypass: the manoeuvres, guided by the ultrasound probes, are performed before the left ventricle is allowed to eject blood into the ascending aorta.(ABSTRACT TRUNCATED AT 400 WORDS)

Embolism, Air↗

PubMed1984

[Spontaneous microcavitations in the right cardiac chambers. Microcavitations in the right sections].

Spontaneous echocardiographic contrast has been occasionally detected in the left ventricle of patients with mitral valve prosthesis. Only one case has been so far described in which spontaneous microbubbles have been detected in the right ventricle. We report the clinical and echocardiographic findings of five patients in whom spontaneous echocardiographic contrast was detected in right cardiac chambers: one patient had pulmonary embolism, three patients had mitral valve disease and tricuspid regurgitation, one patient had a congestive cardiomyopathy. These microbubbles can be produced by gas development due to lateral pressure drop secondary to tricuspid regurgitation or to gas absorbed from the intestine, that reach the heart through shunts between the portal and the systemic veins.

Adult↗

PubMed1983

[Gas embolisms during operations on the open heart].

During routine open heart procedure the amount of microbubbles released from the oxygenator and the heart into the arterial circulation were measured by ultrasonic probes, placed over the arterial line and the carotid artery. The significance of microbubbles ejected from the cavities of the heart for cerebral cell injury were studied in an experimental model, analyzing enzyme levels in cerebrospinal fluid. A typical phasic bubble-activity was found in both the arterial line and the carotid artery, with an initial high during the initiation of bypass, a lower plateau during perfusion and a slight increase again with rewarming during reperfusion after releasing the aortic cross clamp. The increase of bubble activity during reperfusion was more pronounced in the carotid artery as bubbles released from the heart were added to those coming from the heart lung machine. After leftsided cardiotomy this activity lasted for up to 20 min after termination of extracorporeal circulation (ECC). The use of filters reduced the bubble activity during perfusion significantly, but did not change the activity during reperfusion and after termination of ECC. Liquor enzyme levels were found normal during and after bubbles reperfusion, but rose significantly after leftsided cardiotomy. CO2 wash-out reduced the increase in liquor enzyme levels markedly.

Animals↗

PubMedDate not supplied

Epidural air injection assessed by transesophageal echocardiography.

BACKGROUND AND OBJECTIVES: The object of this study, using transesophageal echocardiography (TEE) in anesthetized patients, was to investigate the occurrence of venous air embolism (VAE) when air is injected into the epidural space. METHODS: Six patients between the ages of 18 and 50 years (ASA I-II) undergoing general anesthesia in a supine position for nonthoracic surgical procedures were studied. Prior to general anesthesia, an epidural catheter was placed into the epidural space using a Tuohy needle and a standard saline loss-of-resistance technique. Following verification of proper catheter placement, general anesthesia was induced and the trachea intubated. Thereafter, a TEE probe was inserted into the esophagus. After a 10-minute control period, and during continuous TEE videotape recording, 5 mL of air was rapidly injected into the epidural space through the epidural catheter. This was followed 10 minutes later by the epidural injection of 5 mL of room-temperature preservative-free saline. Microbubble echo targets were quantified in a range from 0 to 4+. RESULTS: Venous air microbubble emboli appeared in the circulation within 15 seconds after injecting either air or saline into the epidural space. CONCLUSIONS: No evidence of clinically significant VAE was seen in any patient. The results suggest that drugs injected into the epidural space may have unexpectedly easy access to the venous circulation with a potential to produce unwanted systemic effects. Clinicians should be alert to the possibility that local anesthetics, or any other drug placed epidurally, may rapidly enter the systemic circulation even without the intravenous placement of an epidural catheter.

Adolescent↗

PubMed1993

Epidemiology of decompression sickness under simulated space extravehicular activities.

Several ground-based trials were conducted by NASA at the Lyndon B. Johnson Space Center, Houston, TX, during 1982-90 to examine the risk of altitude decompression sickness (DCS) during space extravehicular activities. There were 22 different pressure profiles involving single and staged decompression procedures, each lasting from 180 to 360 min at the final altitude. A total of 164 healthy subjects participated in 426 exposures to altitude. Symptoms of DCS occurred in 17% (74/426) and circulating microbubbles by precordial Doppler ultrasound were detected in 42% (179/426) of all exposures. About 27% (20/74) of exposures with symptoms resulted in test abort, and one-third of all test aborts required treatment in the hyperbaric chamber. There was about 3.20 times (95% Confidence Interval [95% CI] = 1.56-6.66) higher risk of symptoms in the presence of Doppler-detectable microbubbles. Examination of individual risk factors showed that there was about 4.3 times (95% CI = 1.62-11.50) higher risk of symptoms with increasing number of exposures. These findings emphasize the importance of evaluating risk factors from ground-based trials for application in operational decision-making and treatment strategies.

Adult↗

PubMed1993

Dysbarism: the medical problems from high and low atmospheric pressure.

The most serious problems resulting from a change in ambient pressure are pulmonary barotrauma with air embolism and decompression sickness. The small differential pressures used in ventilators at atmospheric pressure may tear lung tissue and, in diving, deaths have occurred from the expansion of pulmonary gas on an ascent of less than two metres. The bubbles of respired gas that enter the systemic circulation often occlude cerebral arteries and may cause infarction. In decompression sickness, bubbles form in the tissues from supersaturation of the nitrogen or helium absorbed under pressure. Joint pain--the 'bends'--is associated with gas in particular connective tissue. Serious decompression sickness results from the entry of microbubbles into the systemic veins. Large numbers of bubbles trapped in the lung cause an acute respiratory syndrome known as 'chokes'. If the lung filter is overwhelmed, or microbubbles pass into the systemic arteries through an atrial septal defect, they may open the blood-brain barrier, affecting brain and spinal cord function. Untreated, demyelination with relative preservation of axons may occur, the pathological hallmarks of multiple sclerosis. Gas bubble disease requires urgent compression in a hyperbaric chamber and the use of high partial pressures of oxygen.

Atmospheric Pressure↗

PubMed1997

Reversibility in blood-brain barrier, microcirculation, and histology in rat brain after decompression.

To examine the changes in blood-brain barrier (BBB), cerebral microcirculation, and histology from 15 min to 72 h after decompression, 90 rats were exposed to experimental compression to 6 atm abs air for 90 min and subsequent rapid decompression. The disruption of BBB was examined by Evans blue extravasation. The cerebral microcirculation was demonstrated by perfusion with India ink. The area stained with Evans blue and the regions of defective filling with India ink, observed immediately after decompression decreased in size with time and were undetectable 3-24 h after decompression. The edematous brain tissue with enlarged perivascular space and darkly stained nerve cells also decreased to the uncompressed control level 1-24 h after decompression. These reversible dysbaric changes, however, reappeared 48-72 h after decompression. The different mechanisms, the physicochemical effects of microbubbles, and the maturation phenomenon after temporary brain ischemia induced by dysbaric microbubbles may be involved in the brain damage after decompression sickness.

Animals↗

PubMed1998

[Recent progress of the medical ultrasound contrast imaging technology].

Development and research on the ultrasound contrast agents is becoming a very important topic in the field of diagnostic ultrasound. The reason is that ultrasound contrast agents have an enormous potential clinical applications in cardiology, neurology and in vascular medicine. In this report, the problems encountered, the potential use and the future development of microbubble-type ultrasound contrast agents are discussed in detail. In coming years, it is expected that researches will concentrate on the development of long-lifetime and low-toxicity microbubbles contrast agents to overcome the problems that were encountered. After then, by making use of both the linear and non-linear properties of ultrasound contrast agents, the development of new generation ultrasound diagnostic equipment can be expected in the next decade.

Contrast Media↗