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Roberto M. Lang

Publications and source records attributed to Roberto M. Lang.

12 recordsLinked to original sources
PubMed1999

Multicenter Experience Using a New Prototype Transnasal Transesophageal Echocardiography Probe.

Transesophageal echocardiography (TEE) is an invaluable diagnostic tool, particularly in patients with inadequate transthoracic echocardiographic examinations. In addition, continuous TEE has been used to monitor ventricular and valvular performance in the intensive care unit and the operating room. However, current generation transesophageal probes have limitations in the critical care setting due to their size. Recently, a prototype miniaturized transesophageal probe was developed to overcome these limitations. This probe was used by five medical centers for 194 examinations. A large proportion of these patients were in the intensive care unit (43%), as well as mechanically ventilated (39%). Seventy percent (70%) of the subjects in this study were intubated nasally with the prototype probe, with a success rate of 88.5%. Oral intubation was successful in every case. Subject tolerance was good, and 25% of the patients were intubated for > 1 h. Nasal intubation with the probe was more likely in intensive care patients, ventilated subjects, and patients who were intubated for > 1 hour. TEE with this miniaturized probe is feasible and safe even in multi-instrumented critical care patients. This probe provides adequate diagnostic imaging capabilities and may allow imaging over prolonged periods of time, making it suitable for the serial monitoring of ventricular performance.

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PubMed1999

Evaluation of Left Ventricular Diastolic Performance Using Automated Border Detection.

Acoustic quantification (AQ) is a noninvasive technique which provides online left ventricular (LV) area/volume waveforms. The filling portion of the AQ waveform can be used to assess LV diastolic properties. Analysis of signal-averaged AQ curves enhances the waveforms and allows reliable, quantitative, and automated analysis. From signal-averaged AQ LV waveforms, the phases of diastole can be easily detected and several parameters of diastolic performance calculated. Analysis of signal-averaged LV waveforms is complementary to that of LV AQ analysis. AQ has been used to identify diastolic dysfunction in patients with LV hypertrophy and systemic hypertension. Normal values of these parameters are age dependent and reference values will soon be available.

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PubMed1999

Acoustic Quantification Today and Its Future Horizons.

We briefly review previously published work based on the uses of acoustic quantification (AQ) or validation of this technology. We also discuss the limitations of AQ in a critical review of the literature, including operator dependency, signal noise, and low temporal resolution. We describe some enhancements made to AQ software to address these limitations and improve the accuracy of this technique, including digital beam processing, harmonic imaging, and signal averaging. Several anticipated applications are also briefly described for those interested in the future development of this technology. These future applications include noninvasive long-term monitoring of ventricular function and objective assessment of regional ventricular wall motion in two and three dimensions.

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PubMed1999

Color Kinesis: New Technique or Just Another Display of Acoustic Quantification?

Color kinesis is a relatively new echocardiographic technique that allows color encoding of endocardial motion in real time. We briefly review the literature on the current clinical uses and limitations of this technique, as well as its potential future applications based on some of our results. The major advantage of this modality is that it provides the basis for objective and automated evaluation of regional systolic and diastolic function, which may have a direct impact on the diagnosis of various myocardial disease states and, in particular, coronary artery disease.

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PubMed1999

Evaluation of Global and Regional Right Ventricular Function Using Automated Border Detection Techniques.

Quantitative evaluation of right ventricular (RV) function remains challenging due to the complex geometry of this chamber, which precludes the use of simple geometric assumptions. Automated border detection (ABD) techniques, which provide online changes in cardiac chamber dimensions, have been predominantly used for quantitative assessment of global as well as regional left ventricular function. Recently, acoustic quantification has been validated for quantitative evaluation of global RV function, and color kinesis has been used to objectively assess systolic and diastolic regional RV function. In this article, the main studies validating ABD for the objective assessment of global RV function and the current clinical uses of this technique are reviewed. In addition, technical guidelines and limitations of ABD techniques are described, and potential applications of color kinesis for quantitative assessment of regional systolic and diastolic RV performance are detailed. ABD techniques provide new insights into right atrial and RV systolic and diastolic properties. The clinical value of these techniques in the diagnosis, prognosis, and potential guidance of therapeutic management of RV dysfunction remains to be determined.

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PubMed1999

Use of Transesophageal Echocardiography for the Assessment of Traumatic Aortic Injuries.

Acute traumatic lesions of the thoracic aorta or its branches (TLA) constitute highly lethal yet treatable injuries that are increasingly diagnosed in surviving patients. Traumatic disruptions are limited to the region of the aortic isthmus in approximately 90% of cases. Unlike aortography, usually referred as the gold standard diagnostic technique, transesophageal echocardiography (TEE) is a noninvasive imaging modality that can be rapidly performed at the patient bedside. Accordingly, TEE is being increasingly used as a first-line screening test for the evaluation of patients with suspected TLA. The TEE signs associated with TLA depend on the anatomic type of aortic disruption. After a period of validation, multiplane TEE allows accurate diagnosis of traumatic disruptions of the aortic isthmus, with a sensitivity of 88% (range, 57%-100%) and a specificity of 96% (range, 84%-100%). False-negative TEE results have been mainly attributed to lacerations of aortic branches. Accordingly, aortography must be routinely performed when a traumatic injury to brachiocephalic arteries is suspected. False-positive TEE findings have been associated with the presence of ultrasound artifacts or atherosclerotic changes that mimic TLA. Accurate determination of the depth of aortic wall tears and diagnosis of blunt cardiac injuries during the TEE study are crucial to guide patient management. The presence of TEE signs associated with imminent risk of adventitial rupture should lead to prompt surgery. The use of TEE as a first-line imaging modality simplifies the initial assessment of patients at high risk for TLA and helps guide acute management.

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PubMed1998

Color Kinesis: Principles of Operation and Technical Guidelines.

Color kinesis is a new echocardiographic technique that aids in the assessment of global and regional left ventricular performance during either systole or diastole. Color kinesis uses automated border detection technology based on backscatter data to display both the magnitude and timing of endocardial motion in real time. The color kinesis display superimposes a color overlay on the two-dimensional echocardiographic image; the number of color pixels represents the magnitude of endocardial motion, while the different colors represent the timing of endocardial motion according to a predefined color scheme. Because color kinesis is an operator-dependent technique, the steps involved in performing a technically adequate study will be reviewed as well as the pitfalls and technical limitations. The potential clinical applications of color kinesis will also be discussed.

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PubMed1998

Left Ventricular Diverticula and Aneurysms: Congenital and Acquired Lesions.

Congenital diverticula and aneurysms are extremely rare cardiac anomalies, in contrast to acquired ventricular outpouchings, which are relatively commonplace. The English language literature pertaining to congenital lesions in particular is somewhat sparse; in addition, a definitive classification scheme for these malformations is lacking. In this manuscript, we review the salient literature pertaining to congenital diverticula, congenital aneurysms, acquired true aneurysms, "aneurysms" of the membranous interventricular septum, and left ventricular pseudoaneurysms. This is performed with attention to the clinical and pathological characteristics, etiology (if known), prognosis, and suggested management of these lesions. Important echocardiographic features are delineated in the figure legends; however, the differentiation between these lesions often must be made on clinical grounds as well.

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PubMed1998

Transnasal Transesophageal Stress Echocardiography.

Exercise echocardiography is a widely used modality for the noninvasive assessment of coronary artery disease. However, limitations exist inherent to the acquisition of transthoracic echocardiographic images. Although transesophageal echocardiography has been used during pacing or pharmacological stress, its use during exercise stress testing has not been clinically feasible due to the large probe size. Recently, a miniaturized transesophageal probe was developed, and we sought to test the feasibility of using this probe during graded treadmill exercise testing. Normal subjects were studied with transnasal echocardiography during upright treadmill exercise testing. The transnasal probe was passed in 13 of the 15 subjects. Excellent-quality monoplane two-dimensional echocardiographic images were obtained in all patients in the upright position. During exercise treadmill testing, high quality clinically useful echocardiographic images of the left ventricular short axis could be maintained. We conclude that transnasal transesophageal stress echocardiography may offer a new modality for the exercise assessment of ischemic heart disease.

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PubMed1997

Effects of Temperature on Albunex and FS069 Echocardiographic Contrast Agents: In Vitro Investigation Using Ultrasonic Irradiation.

The effects of temperature on the stability of two contrast agents, Albunex and perfluoropropane filled albumin microspheres (FS069), were investigated by studying the variations in their reflective properties, induced by high dose ultrasound irradiation at different temperatures. Diluted contrast agents were introduced into a 3.5-mL latex balloon, placed in a plastic water tank, and continuously irradiated over a period of 6 minutes using different power levels: 0, 20, 25, and 30 dB. The irradiation was interrupted for imaging every 30 seconds for 2 seconds. The protocol was carried out at three different temperatures: 8 degrees C, 22 degrees C, and 37 degrees C. For each temperature, the concentration of contrast solution was matched to produce approximately the same initial video intensity. Time variations in mean video intensity in the balloon cross section were studied. Contrast enhancement was found to be directly related to temperature. Under continuous ultrasonic irradiation, video intensity gradually decreased over time. This decrease was dependent on both transmitted power and temperature, and was more pronounced with Albunex when compared to FS069 (P < 0.05). Abruptly dropping temperature consistently resulted in rapid, irreversible disappearance of contrast induced by Albunex. Temperature affects the reflectivity and stability of diluted Albunex and FS069. To enhance the reproducibility of contrast enhancement achieved by these agents, their temperature should be carefully controlled.

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