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Biomedical subjects

R M Lang

Publications and source records attributed to R M Lang.

At least 19 recordsLinked to original sources
PubMed1999

A modified definition for peripartum cardiomyopathy and prognosis based on echocardiography.

The diagnosis of peripartum cardiomyopathy is one of exclusion, made after careful search for an underlying cause. Research in this area is compromised by the reliance of some on clinical criteria alone without strict echocardiographic criteria. This article argues for uniform criteria that define peripartum cardiomyopathy, similar to the criteria for idiopathic dilated cardiomyopathy set forth by a National Heart, Lung, and Blood Institute-sponsored workshop and proposes that the new definition include heart failure within the last month of pregnancy or 5 months postpartum; absence of preexisting heart disease; no determinable etiology, the traditional definition; and strict echocardiographic criteria of left ventricular dysfunction: ejection fraction less than 45%, or M-mode fractional shortening less than 30%, or both, and end-diastolic dimension more than 2.7 cm/m2. Mortality from peripartum cardiomyopathy remains high, 25-50%, and a recent review related long-term prognosis to echocardiographic measures of left ventricular chamber dimension and function at diagnosis and recovery. We describe a modified pharmacologic echocardiographic stress test that might be useful in determining left ventricular contractile reserve in women believed to be recovered by routine echocardiographic studies. The test reproduces hemodynamic stress akin to pregnancy, and the data might be useful when counseling women on future childbearing. Women who respond with reduced cardiac reserve might be advised to avoid pregnancy.

Cardiomyopathies↗
PubMed1999

Objective evaluation of regional left ventricular wall motion during dobutamine stress echocardiographic studies using segmental analysis of color kinesis images.

OBJECTIVES: To test the feasibility of objective and automated evaluation of echocardiographic stress tests, we studied the ability of segmental analysis of color kinesis (CK) images to detect dobutamine-induced wall motion abnormalities and compared this technique with inexperienced reviewers of conventional gray-scale images. BACKGROUND: Conventional interpretation of stress echocardiographic studies is subjective and experience dependent. METHODS: CK images were obtained in 89 of 104 consecutive patients undergoing clinical dobutamine stress studies and were analyzed using custom software to calculate regional fractional area change in 22 segments in four standard views. Each patient's data obtained at rest was used as a control for automated detection of dobutamine-induced wall motion abnormalities. Independently, studies were reviewed without CK overlays by two inexperienced readers who classified each segment's response to dobutamine. A consensus reading of two experienced reviewers was used as the gold standard for comparisons. In a subgroup of 16 patients, these consensus readings and CK detection of wall motion abnormalities were compared with coronary angiography. RESULTS: The consensus reading detected ischemic response to dobutamine in 43 of 1958 segments in 23 of 89 patients. Automated detection of stress-induced wall motion abnormalities correlated more closely with the standard technique than the inexperienced reviewers (sensitivity 0.76 vs. 0.55, specificity 0.98 vs. 0.94 and accuracy 0.97 vs. 0.92). When compared with coronary angiography in a subgroup of patients, analysis of CK images differentiated between normal and abnormal wall motion more accurately than expert readers of gray-scale images (accuracy of 0.93 vs. 0.82). CONCLUSIONS: Analysis of CK images allows fast, objective and automated evaluation of regional wall motion, sensitive enough for clinical dobutamine stress data and more accurate than inexperienced readers. This method may result in a valuable adjunct to conventional visual interpretation of dobutamine stress echocardiography.

Aged↗
PubMed1999

Quantitative evaluation of left ventricular function in a TransgenicMouse model of dilated cardiomyopathy with 2-dimensional contrast echocardiography.

The study of transgenic mouse models of human cardiovascular disease has been limited by the small size and high heart rate of the mouse heart. Advances in digital echocardiographic imaging equipment have provided the high spatial and temporal resolution necessary for 2-dimensional (2D) in vivo imaging of the mouse heart. The goal of this study was to test the use of contrast-enhanced 2D echocardiography to quantitatively assess left ventricular (LV) size and function in normal and transgenic mice with dilated cardiomyopathy. Images were obtained with a 12-MHz broadband transducer in the parasternal short-axis view in 8 control mice and 8 transgenic mice with dilated cardiomyopathy resulting from expression of a dominant-negative CREB transcription factor in the heart. LV opacification was achieved with injections of human albumin microspheres, injectable suspension (Optison) (15 to 30 microliter bolus). LV area was measured throughout the cardiac cycle with manual frame-by-frame tracing of the endocardial boundary. End-systolic and end-diastolic areas (ESA and EDA) were measured and fractional area change (FAC) calculated in both groups at baseline and during administration of dobutamine (40 microgram/kg/min intravenously). High-quality 2D images, which yielded LV area over time waveforms, were obtained in all mice. Under baseline conditions, ESA was significantly higher and FAC lower in the transgenic mice compared with their controls. During administration of dobutamine, normal mice had significantly smaller ESA and significantly larger FAC compared with baseline conditions, whereas this trend did not reach significance in the transgenic mice. In summary, quantitative assessment of LV size and function may be achieved with contrast-enhanced 2D echocardiographic imaging. This technique promises to facilitate studies of pathophysiology in murine models of human cardiovascular disease.

Animals↗
PubMed1999

Identification of cardiac masses and abnormal blood flow patterns with harmonic power Doppler contrast echocardiography.

Power Doppler is an ultrasound technique that color-encodes the change in amplitude of the ultrasound signal, which reflects changes in the position of scatterers between ultrasound pulses. Power Doppler can be used with echocardiographic contrast agents in a harmonic imaging mode to opacify a cardiac chamber. The opacification of a cardiac chamber can aid in visualizing the silhouette of intracardiac masses and displaying blood flow patterns. Four cases are presented that demonstrate the use of harmonic power Doppler to aid in the identification of a left ventricular apical thrombus, a left atrial thrombus, and a left ventricular pseudoaneurysm.

Aged↗
PubMed1999

Left atrial appendage stenosis.

Narrowing at the mouth of the left atrial appendage has been reported after partial surgical ligation of the appendage. This report describes a patient, without prior cardiac surgery, who had an anatomic narrowing at the opening of the left atrial appendage demonstrated by 2-dimensional, Doppler, and color Doppler echocardiography.

Aged↗
PubMed1999

Quantitative assessment of regional right ventricular function with color kinesis.

We used color kinesis, a recent echocardiographic technique that provides regional information on the magnitude and timing of endocardial wall motion, to quantitatively assess regional right ventricular (RV) systolic and diastolic properties in 76 subjects who were divided into five groups, as follows: normal (n = 20), heart failure (n = 15), pressure/volume overload (n = 14), pressure overload (n = 12), and RV hypertrophy (n = 15). Quantitative segmental analysis of color kinesis images was used to obtain regional fractional area change (RFAC), which was displayed in the form of stacked histograms to determine patterns of endocardial wall motion. Time curves of integrated RFAC were used to objectively identify asynchrony of diastolic endocardial motion. When compared with normal subjects, patients with pressure overload or heart failure exhibited significantly decreased endocardial motion along the RV free wall. In the presence of mixed pressure/volume overload, the markedly increased ventricular septal motion compensated for decreased RV free wall motion. Diastolic endocardial wall motion was delayed in 17 of 72 segments (24%) in patients with RV pressure overload, and in 31 of 90 segments (34%) in patients with RV hypertrophy. Asynchrony of diastolic endocardial wall motion was greater in the latter group than in normal subjects (16% versus 10%: p < 0.01). Segmental analysis of color kinesis images allows quantitative assessment of regional RV systolic and diastolic properties.

Adult↗
PubMed1998

Use of harmonic imaging without echocardiographic contrast to improve two-dimensional image quality.

The aim of this study was to determine whether harmonic imaging (HI) improves endocardial visualization during 2-dimensional echocardiography without echocardiographic contrast. HI differs from fundamental imaging (FI) by transmitting ultrasound at one frequency and receiving at twice the transmitted frequency. This technique has been used in conjunction with contrast echocardiography to enhance myocardial contrast visualization. HI and FI were sequentially performed in 20 patients. Images were digitally stored and subsequently reviewed by 2 observers for the quality of endocardial visualization. In addition, acoustic quantification was performed in both FI and HI modes and endocardial tracking qualitatively judged. HI was compared with FI during dobutamine stress echocardiography in 17 patients who were imaged at baseline and peak stress. Overall, the harmonic images had less clutter and better myocardial blood contrast. Individual segments were better visualized with HI in 30% to 73% of cases. The acoustic quantification endocardial tracking was rated better with HI in 67% of short-axis views and in 58% of apical 4-chamber views. During dobutamine stress testing the overall number of interpretable segments improved from 64% for FI to 84% with HI. Many segments traditionally difficult to image were improved with HI. HI without the use of contrast agents improved endocardial visualization during routine 2-dimensional echocardiography. This improved endocardial visualization led to better endocardial tracking with acoustic quantification and to more segments being clinically interpretable during dobutamine stress testing.

Cardiotonic Agents↗
PubMed1998

Assessment of small-diameter aortic mechanical prostheses: physiological relevance of the Doppler gradient, utility of flow augmentation, and limitations of orifice area estimation.

BACKGROUND: Noninvasive assessment of functionally stenotic small-diameter aortic mechanical prostheses is complicated by theoretical constraints relating to the hemodynamic relevance of Doppler-derived transprosthetic gradients. To establish the utility of Doppler echocardiography for evaluation of these valves, 20-mm Medtronic Hall and 19-mm St Jude prostheses were studied in vitro and in vivo. METHODS AND RESULTS: Relations between the orifice transprosthetic gradient (equivalent to Doppler), the downstream gradient in the zone of recovered pressure (equivalent to catheter), and fluid mechanical energy losses were examined in vitro. Pressure-flow relations across the 2 prostheses were evaluated by Doppler echocardiography in vivo. For both types of prosthesis in vitro, the orifice was higher than the downstream gradient (P<0.001), and fluid mechanical energy losses were as strongly correlated with orifice as with downstream pressure gradients (r2=0.99 for both). Orifice and downstream gradients were higher and fluid mechanical energy losses were larger for the St Jude than the Medtronic Hall valve (all P<0.001). Whereas estimated effective orifice areas for the 2 valves in vivo were not significantly different, model-independent dynamic analysis of pressure-flow relations revealed higher gradients for the St Jude than the Medtronic Hall valve at a given flow rate (P<0.05). CONCLUSIONS: Even in the presence of significant pressure recovery, the Doppler-derived gradient across small-diameter aortic mechanical prostheses does have hemodynamic relevance insofar as it reflects myocardial energy expenditure. Small differences in function between stenotic aortic mechanical prostheses, undetectable by conventional orifice area estimations, can be identified by dynamic Doppler echocardiographic analysis of pressure-flow relations.

Aortic Valve Stenosis↗
PubMed1998

Dilated cardiomyopathy in transgenic mice expressing a dominant-negative CREB transcription factor in the heart.

Idiopathic-dilated cardiomyopathy (IDC) is a common primary myocardial disease of unknown etiology characterized by progressive biventricular failure, cardiac dilatation, and premature mortality. Here we show that transgenic mice expressing a dominant-negative form of the CREB transcription factor (CREBA133) under the control of the cardiac myocyte-specific alpha-MHC promoter develop dilated cardiomyopathy that closely resembles many of the anatomical, physiological, and clinical features of human IDC. Between 2 and 20 wk of age, these mice develop four chamber cardiac dilatation, decreased systolic and diastolic left ventricular function, and attenuated contractile responses to the beta-adrenergic agonist, isoproterenol. Histologically, the CREBA133 hearts demonstrated both atrophic and hypertrophied fibers as well as significant interstitial fibrosis. These anatomical and hemodynamic changes were associated with hepatic congestion and peripheral edema, intracardiac thrombi, and premature mortality. Taken together, these results implicate CREB as an important regulator of cardiac myocyte function and provide a genetic model of dilated cardiomyopathy which should facilitate studies of both the pathogenesis and therapy of this clinically important disorder.

Animals↗
PubMed1998

Quantitative evaluation of global and regional left ventricular diastolic function with color kinesis.

BACKGROUND: Diastolic wall motion asynchrony is a major determinant of impaired left ventricular (LV) filling in patients with concentric hypertrophy and coronary artery disease. We evaluated the ability of Color Kinesis, a new echocardiographic technique that color-encodes endocardial motion, to quantitatively assess global and regional LV filling properties. METHODS AND RESULTS: Color Kinesis images and mitral and pulmonary vein flow Doppler data were acquired in 29 patients with LV hypertrophy and 29 age-matched control subjects. In addition, Color Kinesis data were correlated to coronary angiographic findings in 15 patients with suspected coronary artery disease. Segmental analysis of Color Kinesis images was used to obtain time histograms of regional diastolic fractional area change, wherein early and late peaks (peaks 1 and 2) reflected rapid LV filling and atrial contraction, respectively. Regional mean LV filling time and filling curves were used to objectively identify diastolic endocardial motion asynchrony in patients with LV hypertrophy and coronary artery disease. None of the mitral and pulmonary vein Doppler indices differentiated patients with normalized mitral Doppler profile (n=13) from control subjects, whereas reduced peak1/peak2 ratio and prolonged mean filling time indicated augmented contribution of atrial contraction toward LV filling (P<.05). In 22 of 25 patients with LV hypertrophy and preserved systolic function and in all patients with coronary artery disease, delayed diastolic endocardial motion was observed in at least one segment. CONCLUSIONS: Analysis of Color Kinesis images provides objective assessment of global and regional LV filling properties and allows identification of both diastolic dysfunction in patients with normalized Doppler indices and wall motion asynchrony.

Adult↗
PubMed1998

The relationship between cardiothoracic ratio and left ventricular ejection fraction in congestive heart failure. Digitalis Investigation Group.

BACKGROUND: Left ventricular ejection fraction (EF) is a valuable prognostic index in patients with congestive heart failure (CHF). Although EF can be readily measured, many clinicians use roentgenographic heart size as a clue to differentiate systolic from diastolic dysfunction, even in the absence of solid supportive data. OBJECTIVE: To test the hypothesis that the cardiothoracic ratio (CTR) measured from the chest roentgenogram can be used to estimate left ventricular EF in individuals with CHF. METHODS: To answer this question, the database of the Digitalis Investigation Group trial was used. The CTR, determined using the Danzer method, and quantitative EF, measured locally using angiographic, radionuclide, or 2-dimensional echocardiographic techniques, were compared in 7476 patients with clinical CHF (New York Heart Association functional classes I-IV) due to acquired left-sided cardiac disease of ischemic, hypertensive, idiopathic, and alcohol-related causes. RESULTS: Mean (+/-SD) CTR for the cohort was 0.53+/-.07. Mean (+/-SD) EF was 31.7%+/-12.2%. A weak, negative correlation between CTR and EF was observed (r=-0.176). Similar findings were obtained when the results were stratified by cause of CHF, presence of clinically defined right ventricular dysfunction, and method of EF measurement. Categorical analysis failed to yield a CTR cutoff point that facilitated useful segregation of individuals with an EF greater than 35% or 35% and below; greater than 40% or 40% and below; and greater than 45% or 45% and below in any patient group. CONCLUSIONS: Although a weak, negative correlation exists between CTR and EF, this relationship does not allow for accurate determination of systolic function in individual patients with CHF. Considering the morbidity and mortality associated with CHF, and the clinical implications of systolic function in this syndrome, direct measurement of EF is recommended.

Aged↗
PubMed1998

Aortic stenosis.

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Aged↗
PubMed1998

Use of color kinesis for evaluation of left ventricular filling in patients with dilated cardiomyopathy and mitral regurgitation.

OBJECTIVES: We tested the feasibility of using analysis of color kinesis images to objectively assess global and regional left ventricular (LV) diastolic function in patients with dilated cardiomyopathy (DCM). In addition, the ability of this technique to track drug-induced changes on LV diastolic properties was studied. BACKGROUND: Diastolic dysfunction contributes to symptomatology in patients with DCM. The assessment of LV diastolic function using conventional Doppler echocardiography is indirect and is confounded by multiple variables. Moreover, the noninvasive evaluation of regional diastolic properties is difficult. In contrast, color kinesis directly tracks and color-encodes regional diastolic endocardial motion. METHODS: We studied 24 patients with DCM and mitral regurgitation (MR) and 24 age-matched normal subjects. Transmitral and pulmonary vein flow velocities were measured using pulsed Doppler echocardiography. Diastolic color kinesis images were used to calculate indexes of magnitude and timing of global and regional diastolic function. Diastolic asynchrony was evaluated in different subgroups of patients with DCM. The effects of drug infusions (nitroprusside and dobutamine) were also studied. RESULTS: Color kinesis indexes of global diastolic function showed significant differences between patients with DCM and normal subjects. Compared with Doppler indexes, color kinesis was less confounded by MR and was capable of differentiating between drug-induced lusitropic and vasodilator effects. Diastolic asynchrony was increased in patients with DCM and severe MR. CONCLUSIONS: Quantitative analysis of global and regional LV diastolic function in patients with DCM using color kinesis is feasible.

Adult↗
PubMed1998

Acoustic quantification indexes of left ventricular size and function: effects of signal averaging.

BACKGROUND: The aim of this study was to evaluate the clinical utility of using signal-averaged acoustic quantification (SAAQ) waveforms for improved assessment of left ventricular (LV) size and function. METHODS AND RESULTS: Four separate protocols were performed in 47 subjects. SAAQ waveforms were used to assess alterations in LV function induced by dobutamine (15 microg/kg per minute) and esmolol (200 microg/kg per minute) in eight normal subjects. Subsequently, we analyzed SAAQ waveforms obtained in 12 patients with LV dysfunction secondary to dilated cardiomyopathy and 12 age-matched normal subjects. Finally, we developed computer software for monitoring of LV function on the basis of continuous acquisition and repeated analysis of SAAQ waveforms. We compared the interbeat variability in indexes of LV function obtained from raw AQ and SAAQ during 10 minutes of steady-state monitoring in eight patients undergoing transesophageal echocardiography. The feasibility of long-term monitoring in the intensive care setting was then studied in seven patients undergoing abdominal surgery. Our analysis tracked variations in LV function induced by dobutamine and esmolol. Significant differences in all measured indexes were found between normal subjects and patients with dilated cadiomyopathy. Signal averaging during steady-state monitoring significantly reduced the interbeat variability of all indexes (21% to 42%). In the operating room, the SAAQ monitoring system tracked hemodynamic changes in close agreement with invasive measurements. CONCLUSIONS: SAAQ allows fast and easy quantification of LV function and can track hemodynamic trends in the operating room setting.

Adrenergic beta-Agonists↗
PubMed1998

Cor triatriatum in a 70-year-old woman: role of transesophageal echocardiography and dynamic three-dimensional echocardiography in diagnostic assessment.

In this report we describe a 70-year-old woman with unrecognized nonobstructive cor triatriatum (CT). She had concomitant mitral regurgitation and coronary artery disease. Diagnosis of CT and its hemodynamic assessment were accomplished by transesophageal echocardiography. Dynamic three-dimensional echocardiography demonstrated multiple fenestrations in the left atrial membrane. Intraoperative findings confirmed the diagnostic accuracy of three-dimensional echocardiography. To our knowledge, this is the first case of CT that has anatomic correlation with three-dimensional echocardiography.

Aged↗
PubMed1998

Age dependency of left atrial and left ventricular acoustic quantification waveforms for the evaluation of diastolic performance in left ventricular hypertrophy.

We evaluated diastolic performance in 50 normal subjects and 50 patients with concentric left ventricular (LV) hypertrophy. Age-dependent normal values were determined for LV and left atrial (LA) acoustic quantification parameters. Pulsed wave Doppler echocardiography was also performed on all subjects. Patients with LV hypertrophy had higher peak velocities of atrial contraction and atrial contributions to filling. The acoustic quantification waveforms revealed lower rapid filling percentage of total filling and lower peak rapid filling rates. The LA acoustic quantification analysis confirmed the dependence on active atrial emptying in the patients with LV hypertrophy. There were significant correlations with age for most of the LV and LA acoustic quantification parameters. Acoustic quantification provided confirmatory results in subjects with an abnormal relaxation or restrictive Doppler pattern. In subjects with a normal Doppler pattern, the acoustic quantification was of added diagnostic value, identifying abnormalities in 77% to 80% of the patients.

Adult↗