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Biomedical subjects

Roberto M Lang

Publications and source records attributed to Roberto M Lang.

At least 37 records · Page 2Linked to original sources
PubMed2006

Automated interpretation of regional left ventricular wall motion from cardiac magnetic resonance images.

UNLABELLED: Magnetic resonance (MR) diagnosis of regional left ventricular (LV) dysfunction relies on visual interpretation of cine images that suffers from wide inter-observer variability, especially when performed by readers not specifically trained in the assessment of LV wall motion. Quantitative analysis tools, though widely available, are rarely used because they provide large amounts of detailed information, the interpretation of which requires additional time-consuming processing. We tested the feasibility of fast automated interpretation of regional LV function using computer analysis of this wall motion information. METHODS: Dynamic, ECG-gated, steady-state free precession short-axis images were obtained in 6-10 slices in 28 subjects (10 normal volunteers; 18 patients). Images were reviewed by an expert cardiologist who provided "gold standard" grades (normal, abnormal) for regional wall motion and, independently, by four radiologists. Same images were then analyzed using custom software. Regional fractional area changes computed in normal volunteers were used to obtain the optimal segment- and slice-specific threshold values for automated classification of regional wall motion for each patient. The levels of agreement with the "gold standard" grades were compared between the radiologists and the automated interpretation. RESULTS: While the visual interpretation required 2-5 minute per patient, the automated interpretation required < 1 sec, after endocardial border detection was complete. The automated interpretation resulted in higher sensitivity, specificity, and accuracy (84%, 77%, 79%, respectively) than the radiologists' grades (80%, 76%, 77%, respectively) and eliminated the high interobserver variability. CONCLUSION: Once the endocardial boundaries are defined, computer analysis of the regional wall motion information allows accurate, fully automated, immediate, objective and experience-independent interpretation of regional LV function.

Automation↗
PubMed2005

Myocardial contrast echocardiography for the detection of coronary artery stenosis: a prospective multicenter study in comparison with single-photon emission computed tomography.

OBJECTIVES: The purpose of this study was to compare myocardial contrast echocardiography (MCE) with single-photon emission computed tomography (SPECT) for the detection of significant coronary artery disease (CAD) in patients with symptoms suggestive of CAD. BACKGROUND: Single-photon emission computed tomography is a well-established method of assessing patients with CAD. Myocardial contrast echocardiography is a new technique allowing bedside assessment of myocardial perfusion. We hypothesized that MCE was comparable to SPECT in the assessment of patients with known or suspected CAD. METHODS: A total of 123 patients scheduled for coronary angiography underwent intermediate (mechanical index 0.5) triggered replenishment MCE and SPECT imaging at rest and after vasodilator stress. Coronary angiography was performed within four weeks of stress imaging. RESULTS: In total, 96 of 123 (78%) patients demonstrated CAD (stenosis >/=50%). There was no difference in the sensitivity of MCE compared with SPECT in the detection of CAD (84% vs. 82%; p = NS), and both demonstrated similar specificity (56% vs. 52%, respectively). In patients with multivessel disease, MCE and SPECT also demonstrated similar sensitivity (91% and 88%, respectively) for the detection of CAD. Agreement between MCE and SPECT for the presence or absence of CAD was 73%. CONCLUSIONS: Myocardial contrast echocardiography is comparable to SPECT in the detection of CAD not only on a patient basis but also in the localization of disease by vascular territory in a relatively high-risk population.

Contrast Media↗
PubMed2005

Imaging and quantification of myocardial perfusion using real-time three-dimensional echocardiography.

OBJECTIVES: We tested the feasibility of real-time three-dimensional echocardiographic (RT3DE) perfusion imaging and developed and validated an algorithm for volumetric analysis of myocardial contrast inflow. The study included three protocols wherein perfusion was measured: 1) in an ex-vivo model of controlled global coronary flow, 2) in an in-vivo model during regional perfusion variations, and 3) in humans during pharmacologically induced hyperemia. BACKGROUND: The RT3DE technology offers an opportunity for myocardial perfusion imaging without multi-slice reconstruction and repeated contrast maneuvers. METHODS: Electrocardiographically triggered harmonic RT3DE datasets were acquired (Philips 7500) while infusion of Definity was initiated and reached a steady state. Protocol 1 was performed in nine isolated rabbit hearts and included three coronary flow levels. In protocol 2, changes in regional perfusion caused by partial left anterior descending artery occlusion were measured in five pigs. In protocol 3, adenosine-induced changes in perfusion were measured in eight normal volunteers. Myocardial video-intensity (MVI) was measured over time in three-dimensional (3D) slices to calculate peak contrast inflow rate (PCIR). In pigs, PCIR was measured on a regional basis and validated against microspheres. RESULTS: The RT3DE imaging allowed selection of slices for perfusion analysis in rabbit hearts, pigs, and humans. Administration of contrast resulted in clearly visible and quantifiable changes in MVI. In rabbits, The PCIR progressively decreased with coronary flow (p < 0.0001). In pigs, coronary occlusion caused a 59 +/- 26% decrease in PCIR exclusively in the left anterior descending artery territory (p < 0.05) in agreement with microspheres. In humans, adenosine increased PCIR to 198 +/- 57% of baseline (p < 0.05). CONCLUSIONS: Contrast-enhanced RT3DE imaging provides the basis for volumetric imaging and quantification of myocardial perfusion.

Adenosine↗
PubMed2005

Predictors of long-term mortality in patients with ischemic stroke referred for transesophageal echocardiography.

BACKGROUND AND PURPOSE: Findings on transesophageal echocardiography (TEE) after ischemic stroke predict recurrent embolic events and prompt therapy; however, the additive predictive power of TEE findings on long-term mortality is unknown. Our goal was to study the impact of TEE findings on all cause mortality in ischemic stroke patients referred for TEE. METHODS: We reviewed 245 consecutive patients who underwent TEE for ischemic stroke of undetermined origin (2000 to 2003). Long-term survival was assessed using the Social Security Death Index. RESULTS: In a mean follow-up period of 3.0 (1.4 to 4.8) years, death occurred in 19.2% of patients. TEE findings included patent foramen ovale (18.8%), left atrium/left ventricle thrombus (2.4%), spontaneous echo contrast (3.7%), atrial septal aneurysm (3.3%), valve vegetation/mass/tumor (7.8%), complex aortic atheroma ([CAA]; 14.7%), and the composite of any cardiac source of embolus (39.2%). A total atherosclerotic burden (TAB) score was also recorded. On Cox hazard regression analysis, measures of aortic atherosclerosis (CAA [hazard ratio (HR), 2.7; 95% CI, 1.4 to 5.3] or TAB score [HR, 1.4; 95% CI, 1.2 to 1.6]) were independent predictors of death, whereas other TEE findings were not. CONCLUSIONS: In patients with ischemic stroke of undetermined origin referred for TEE, measures of aortic atherosclerosis, including CAA, represent the only TEE findings that predict long-term mortality after all other clinical factors are considered. Further study is needed to determine whether treatments for CAA effect long-term survival in patients with ischemic stroke.

Adult↗
PubMed2005

Rapid online quantification of left ventricular volume from real-time three-dimensional echocardiographic data.

AIMS: Determination of left ventricular (LV) volumes and ejection fraction (EF) from two-dimensional echocardiographic (2DE) images is subjective, time-consuming, and relatively inaccurate because of foreshortened views and the use of geometric assumptions. Our aims were (1) to validate a new method for rapid, online measurement of LV volumes from real-time three-dimensional echocardiographic (RT3DE) data using cardiac magnetic resonance (CMR) as the reference and (2) to compare its accuracy and reproducibility with standard 2DE measurements. METHODS AND RESULTS: CMR, 2DE, and RT3DE datasets were obtained in 50 patients. End-systolic and end-diastolic volumes (ESV and EDV) were calculated from the 2DE images using biplane method of disks. ES and ED RT3DE datasets were analysed using prototype software designed to automatically detect the endocardial surface using a deformable shell model and calculate ESV and EDV from voxel counts. 2DE and RT3DE-derived volumes were compared with CMR (linear regression, Bland-Altman analysis). In most patients, analysis of RT3DE data required <2 min per patient. RT3DE measurements correlated highly with CMR (r: 0.96, 0.97, and 0.93 for EDV, ESV, and EF, respectively) with small biases (-14 mL, -6.5 mL, -1%) and narrow limits of agreement (SD: 17 mL, 16 mL, 6.4%). 2DE measurements correlated less well with CMR (r: 0.89, 0.92, 0.86) with greater biases (-23 mL, -15 mL, 1%) and wider limits of agreement (SD: 29 mL, 24 mL, 9.5%). RT3DE resulted in lower intra-observer (EDV: 7.9 vs. 23%; ESV: 7.6 vs. 26%) and inter-observer variability (EDV: 11 vs. 26%; ESV: 13 vs. 31%). CONCLUSION: Semi-automated detection of the LV endocardial surface from RT3DE data is suitable for clinical use because it allows rapid, accurate, and reproducible measurements of LV volumes, superior to conventional 2DE methods.

Echocardiography, Three-Dimensional↗
PubMed2005

The effect of preoperative statin therapy on cardiovascular outcomes in patients undergoing infrainguinal vascular surgery.

BACKGROUND: Patients undergoing vascular surgery are at increased risk for perioperative cardiovascular (CV) complications. Our goal was to determine the effect of preoperative statin therapy on perioperative cardiac and vascular outcomes, and long-term survival in patients undergoing infrainguinal vascular bypass surgery. METHODS: We retrospectively reviewed consecutive infrainguinal vascular bypass surgeries on 446 patients performed between 1995-2001 at the University of Chicago Medical Center. Information was collected on preoperative statin and beta-blocker use, baseline characteristics, perioperative cardiac and major vascular complications, and length of stay (LOS). Long-term survival was assessed using the Social Security Death Index (SSDI). RESULTS: Thirty day perioperative complications included all-cause mortality (2.5%), CV mortality (1.8%), myocardial infarction (MI) (4.7%), stroke (1.1%), and major peripheral vascular complications (12.8%), and the composite of cardiac and vascular complications [combined CV complications] (17.9%). Statin therapy was associated with fewer combined CV complications (6.9% vs 20.1%, p=0.008), and a shorter LOS (6.4 vs 9.7 days, p=0.007). On multivariate logistic regression analysis, adjusting for significant baseline characteristics including beta-blocker use, statin therapy was independently associated fewer combined CV complications (odds ratio (OR) 0.36, 95% confidence interval (CI) 0.14-0.93, p=0.035) and a shorter LOS (OR 1.49, 95% CI 1.14-1.95, p=0.003). In a mean follow up period of 5.5 years, 215 deaths (48%) occurred. Statin therapy was independently associated with improved long-term survival (OR 0.52, 95% CI 0.32-0.84, p<0.004), after adjusting for significant baseline characteristics. CONCLUSION: Preoperative statin therapy is associated with fewer combined perioperative cardiac and major vascular complications, a shorter length of stay, and improved long-term survival in patients undergoing infrainguinal vascular bypass surgery.

Adrenergic beta-Antagonists↗
PubMed2005

Quantitative diagnosis of stress-induced myocardial ischemia using analysis of contrast echocardiographic parametric perfusion images.

AIMS: Parametric imaging of myocardial perfusion provides useful visual information for the diagnosis of coronary artery disease (CAD). We developed a technique for automated detection of perfusion defects based on quantitative analysis of parametric perfusion images and validated it against coronary angiography. METHODS AND RESULTS: Contrast-enhanced, apical 2-, 3- and 4-chamber images were obtained at rest and with dipyridamole in 34 patients with suspected CAD. Images were analyzed to generate parametric perfusion images of the standard contrast-replenishment model parameters A, beta and A.beta. Each parametric image was divided into six segments, and mean parameter value (MPV) was calculated for each segment. Segmental MPV ratio between stress and rest was defined as a flow reserve index (FRI). Receiver operating characteristics (ROC) analysis was used in a Study group (N=17) to optimize FRI threshold and the minimal number of abnormal segments per vascular territory (LAD and non-LAD), required for automated detection of stress-induced perfusion defects. The optimized detection algorithm was then tested prospectively in the remaining 17 patients (Test group). LAD and non-LAD stenosis >70% was found in 19 and 17 patients, respectively. In the Study group, FRI threshold was: LAD=0.95 and non-LAD=0.68, minimal number of abnormal segments was four and two, correspondingly. Sensitivity, specificity and accuracy in the Test group were: 75%, 67% and 71% in the LAD, and 75%, 75% and 75% in the non-LAD territories. CONCLUSION: Automated quantitative analysis of contrast echocardiographic parametric perfusion images is feasible and may aid in the objective detection of CAD.

Aged↗
PubMed2005

Automated border detection on contrast enhanced echocardiographic images.

BACKGROUND: Accurate determination of left ventricular ejection fraction (LV EF) is of paramount importance in the evaluation of patients with cardiovascular disease. Quantitative techniques for the automated calculation of EF exist however, the robustness of these techniques is dependent on adequate endocardial border definition and therefore are difficult to use in patients with limited images. We sought to combine the endocardial border enhancing effects of contrast echocardiography with an automated border detection technique to provide quantitative and accurate determination of LV EF. METHODS: Thirty-nine consecutive patients referred to nuclear cardiology for EF determination underwent radionuclide angiography followed by echocardiographic imaging using prototype software that allowed automated border detection during contrast infusion. RESULTS: Adequate LV cavity opacification with contrast was possible in 38/39 patients. The mean radionuclide EF was 50+/-16% (range 19-73). There was no statistically significant difference between the mean nuclear EF and averaged echocardiographically determined EF (51+/-18%). The mean bias was 0.6 with limits of agreement that were +15 and -14. CONCLUSION: This study demonstrated that prototype software successfully tracked the contrast enhanced endocardial border allowing accurate calculation of LV EF.

Adult↗
PubMed2005

Volumetric quantification of global and regional left ventricular function from real-time three-dimensional echocardiographic images.

BACKGROUND: Real-time 3D echocardiographic (RT3DE) data sets contain dynamic volumetric information on cardiac function. However, quantification of left ventricular (LV) function from 3D echocardiographic data is performed on cut-planes extracted from the 3D data sets and thus does not fully exploit the volumetric information. Accordingly, we developed a volumetric analysis technique aimed at quantification of global and regional LV function. METHODS AND RESULTS: RT3DE images obtained in 30 patients (Philips 7500) were analyzed by use of custom software based on the level-set approach for semiautomated detection of LV endocardial surface throughout the cardiac cycle, from which global and regional LV volume (LVV)-time and wall motion (WM)-time curves were obtained. The study design included 3 protocols. In protocol 1, time curves obtained in 16 patients were compared point-by-point with MRI data (linear regression and Bland-Altman analyses). Global LVV correlated highly with MRI (r=0.98; y=0.99x+2.3) with minimal bias (1.4 mL) and narrow limits of agreement (+/-20 mL). WM correlated highly only in basal and midventricular segments (r=0.88; y=0.85x+0.7). In protocol 2, we tested the ability of this technique to differentiate populations with known differences in LV function by studying 9 patients with dilated cardiomyopathy and 9 normal subjects. All calculated indices of global and regional systolic and diastolic LV function were significantly different between the groups. In protocol 3, we tested the feasibility of automated detection of regional WM abnormalities in 11 patients. In each segment, abnormality was detected when regional shortening fraction was below a threshold obtained in normal subjects. The automated detection agreed with expert interpretation of 2D WM in 86% of segments. CONCLUSIONS: Volumetric analysis of RT3DE data is clinically feasible and allows fast, semiautomated, dynamic measurement of LVV and automated detection of regional WM abnormalities.

Adult↗
PubMed2005

Diastolic wall motion abnormality after myocardial infarction: relation to neurohormonal activation and prognostic implications.

BACKGROUND: Systolic wall motion abnormality (WMA) after acute myocardial infarction (AMI) is a major determinant of outcome; the presence and importance of diastolic WMA after AMI are unknown. We therefore sought to detect diastolic WMA using color kinesis and to assess its relation to neurohormonal activation and its prognostic importance in a consecutive population with a first AMI. METHODS: Complete color-encoded color kinesis and 2-dimensional and Doppler echocardiography were performed in 149 consecutive patients with documented first AMI within 24 hours of their admission. N-terminal pro-brain natriuretic peptide was measured 3 days after AMI. Study end point was cardiac death or readmission for heart failure. RESULTS: Diastolic area of WMA exceeded the systolic area in all but 5 patients (97%) and was significantly correlated with brain natriuretic peptide (unadjusted beta = .67, P < .0001; adjusted for systolic function, age, Killip class, and overall diastolic function beta = .27, P = .007). Diastolic WMA was also correlated with the number of diseased vessels on coronary angiography (beta = .59, P < .0001). During follow-up, 25 patients died and 11 were readmitted because of recurrent heart failure. On univariate analysis, the area of diastolic WMA was a predictor of the composite end point (hazard ratio 1.07 [95% CI 1.05-1.09], P < .0001) and remained a predictor on multivariate Cox analysis after adjustment of well-known risk factors, left ventricular systolic and overall diastolic functions (hazard ratio 1.09 [95% CI 1.06-1.15], P < .001). CONCLUSION: The extent of diastolic WMA can be assessed early after AMI using color kinesis. Diastolic WMA is associated with neurohormonal activation and angiographic severity of coronary artery disease and provides independent prognostic information.

Aged↗
PubMed2005

Use of hand-carried ultrasound devices to augment the accuracy of medical student bedside cardiac diagnoses.

BACKGROUND: Hand-carried ultrasound (HCU) devices used by cardiologists as extensions of the physical examination have been shown to improve the accuracy of bedside diagnoses. We tested the feasibility of teaching medical students to use HCU devices to make bedside cardiac diagnoses and compared the accuracy of their HCU and physical examinations. METHODS: In all, 10 fourth-year medical students enrolled in a 4-week medical school course on the cardiac examination. Students examined 12 standardized patients at 3 different time intervals: (1) on day 1 of the course; (2) on day 10 after review of cardiac physical examination using traditional teaching methods; and (3) after instruction on the use of HCU devices. Students were scored at each time interval for primary findings (most salient) and all findings, accounting for both errors of commission and omission. Scores could range from +12 to -12 for primary findings and from +22 to -22 for all findings. A perfect score was +12 for primary findings and +22 for all findings. RESULTS: The average score for all students at baseline was -3.2 +/- 3.1 and -5.7 +/- 4.8 for primary and all findings, respectively. A significant improvement in the scores was noted with use of the HCU device (2.6 +/- 3.1 and 5.2 +/- 6.6 for primary and all findings, respectively) compared with the baseline and two subsequent physical examinations. CONCLUSION: Instruction of fourth-year medical students on the use of HCU device is feasible and results in significantly more accurate bedside diagnoses.

Analysis of Variance↗
PubMed2005

Improved semiautomated quantification of left ventricular volumes and ejection fraction using 3-dimensional echocardiography with a full matrix-array transducer: comparison with magnetic resonance imaging.

Our goals were to: (1) develop a technique for 3-dimensional (3D) direct, model-independent quantitative assessment of left ventricular (LV) volume and ejection fraction based on semiautomated detection of LV endocardial surface from transthoracic near real-time full matrix-array 3D echocardiographic (FM3DE) imaging; (2) evaluate the accuracy of LV volumes obtained with this technique, using cardiac magnetic resonance imaging (MRI) measurements as the reference for comparison; and (3) determine the effects of contrast enhancement on the accuracy of FM3DE measurements. A total of 46 patients underwent 2-dimensional echocardiography, FM3DE, and cardiac MRI. End-diastolic volume, end-systolic volume, and ejection fraction were derived from endocardial borders manually traced from 2-dimensional echocardiographic images and from semiautomatically detected LV cavity from FM3DE data. In 14 patients, FM3DE was also acquired with contrast. All measurements were compared with MRI values using linear regression and Bland-Altman analyses. FM3DE was feasible in 44 of 46 patients with LV volumes < 345 mL. LV volumes and ejection fraction computed from FM3DE resulted in higher levels of agreement with MRI than conventional 2-dimensional echocardiography, with lower interobserver variability. With contrast enhancement, FM3DE significantly underestimated LV volumes and showed increased interobserver variability. Semiautomated LV endocardial surface detection from FM3DE images is feasible and results in fast and accurate assessment of LV function.

Adult↗
PubMed2005

High prevalence of important cardiac findings in patients with peripheral arterial disease referred for echocardiography.

BACKGROUND: Patients with peripheral arterial disease (PAD) diagnosed by ankle-brachial index evaluation are known to have high cardiovascular mortality. Although this has primarily been attributed to coexistent coronary artery disease, the prevalence of abnormal echocardiographic findings for patients with PAD has not been studied. Our goal was to study the association between PAD and clinically important echocardiographic findings in symptomatic patients with PAD referred for echocardiography. METHODS: Eligible patients were identified from a database of 615 consecutive patients referred for clinically indicated ankle-brachial index evaluation in our vascular laboratory. Patients were included (n = 309) if they also had a complete transthoracic echocardiogram in the digital echocardiogram database at our institution. Final transthoracic echocardiographic reports were retrospectively reviewed for study indication and clinically important echocardiographic findings. Patients with PAD (ankle-brachial index < 0.9) (n = 190) were compared with patients without PAD (n = 119). RESULTS: Patients with PAD were found to have a high prevalence of clinically important echocardiographic findings, and significantly more clinically important echocardiographic findings (61.6% vs 35.3%, P < .001), including more left ventricular (LV) dysfunction and aortic stenosis, than patients without PAD. On multivariate logistic regression analysis, the presence of PAD was found to be an independent predictor of LV ejection fraction < 50% (odds ratio 2.86, 95% confidence interval 1.54-5.32, P = .001), LV ejection fraction < 35% (odds ratio 2.48, 95% confidence interval 1.22-5.07, P = .02), and any clinically important echocardiographic finding (odds ratio 2.65, 95% confidence interval 1.61-4.36, P < .001). CONCLUSION: In symptomatic patients with PAD referred for echocardiography, there is a high prevalence of clinically important echocardiographic findings, including LV dysfunction, and PAD appears to be an independent predictor of an abnormal echocardiogram. These findings suggest that a prospective echocardiographic screening study in symptomatic patients with PAD is warranted.

Adult↗
PubMed2005

Clinical features of complications from transesophageal echocardiography: a single-center case series of 10,000 consecutive examinations.

BACKGROUND: Transesophageal echocardiography (TEE) is an essential diagnostic tool that has gained widespread use in clinical cardiology. It is considered reasonably noninvasive and safe; however, insertion and operation of the TEE probe may cause hypopharyngeal, esophageal, or gastric trauma. The current study reports a single-center experience of esophagogastric trauma in 10,000 consecutive TEE examinations. METHODS: TEE examinations were performed by 9 attending physicians who were trained in endoscopic procedures and had been performing TEE studies for at least 1 year. RESULTS: One case of hypopharyngeal perforation (0.01%), 2 cases of cervical esophageal perforation (0.02%), and no cases of gastric perforation (0%) occurred after TEE examination. No fatalities (0%) occurred. We describe the clinical characteristics of individuals who experienced esophageal perforation during this 10-year period. CONCLUSIONS: This single-center study demonstrates that TEE examinations are associated with a very low risk of esophagogastric trauma when performed in a safe setting by experienced operators.

Echocardiography, Transesophageal↗
PubMed2005

Quantitative echocardiographic evaluation of myocardial perfusion using interrupted contrast infusion technique: in vivo validation studies and feasibility in human beings.

BACKGROUND: We recently developed a new approach for contrast echocardiographic quantification of myocardial perfusion, based on brief interruptions of contrast infusion, which was designed to overcome the limitations of existing techniques. In this study, our technique was initially validated in a series of animal experiments designed to detect regional perfusion variations in vivo. Subsequently, clinical feasibility of perfusion measurements was tested. METHODS: Regional perfusion was measured transthoracically in 6 anesthetized pigs during baseline, partial left anterior descending coronary artery occlusion, and reperfusion, and validated with fluorescent microspheres. Adenosine-induced changes in perfusion were measured in 8 healthy volunteers. In both protocols, imaging was optimized during contrast infusion (Definity). Infusion was interrupted to allow contrast clearance and images were acquired during subsequent contrast inflow. Myocardial videointensity was measured over time and peak contrast inflow rate was calculated. RESULTS: In pigs, partial coronary occlusion resulted in a 47 +/- 23% decrease in peak contrast inflow rate in the left anterior descending coronary artery perfusion territory (P < .05), which was reversed during reperfusion, without concomitant decrease in other perfusion territories. These changes were in agreement with microspheres. In human beings, adenosine increased peak contrast inflow rate to 278 +/- 123% of baseline (P < .05). CONCLUSION: The interruption of contrast infusion technique is a sensitive tool for accurate quantification of myocardial perfusion, which may constitute an alternative to currently used techniques.

Animals↗