Biomedical subjects

N G Pandian

Publications and source records attributed to N G Pandian.

At least 37 records · Page 2Linked to original sources

PubMed2000

Identification of viable myocardium by perfusion imaging with intravenous contrast echocardiography after acute myocardial infarction.

Myocardial perfusion contrast echocardiography is evolving into an effective method for the evaluation of myocardial blood flow after acute coronary events. The direct injection of ultrasound contrast agents into the aortic and coronary circulation has been shown to accurately identify areas of viable myocardial tissue. Recently, intravenous ultrasound contrast has been found to be useful in detecting microvascular blood flow after the restoration of blood flow in patients with myocardial infarction. We present the case of a patient in whom intravenous ultrasound contrast assisted in the detection of viable myocardial tissue after an acute ischemic syndrome.

Aged↗

PubMed2000

Mitral regurgitation: comprehensive assessment by echocardiography.

Two-dimensional and Doppler echocardiography have become the major modalities for the assessment of mitral regurgitation. The combined use of these techniques provides information regarding the morphology of the valvular apparatus as well as the severity of regurgitation. Transesophageal and three-dimensional echocardiography provide a more-detailed evaluation of valve morphology, which can be valuable in determining suitability for valve repair. In patients with severe mitral regurgitation, echocardiographic assessment of ventricular size and function plays a critical role in determining the optimal timing of surgery.

Echocardiography↗

PubMed2000

Morphological and functional characteristics of patent foramen ovale and their embolic implications.

BACKGROUND AND PURPOSE: Transesophageal echocardiography (TEE) has detected a high prevalence of patent foramen ovale (PFO) in stroke patients, but the clinical implications of the distinctive characteristics of this patency are still a matter of debate. METHODS: We studied 350 patients with acute ischemic stroke or transient ischemic attack (TIA) within 1 week of admission. Of these, 101 (29%) were identified by contrast TEE to have a PFO; 86 patients (25%) were cryptogenic stroke patients, and 163 were excluded because of the presence of a definite or possible arterial or clinical evidence of a source of emboli or small-vessel disease. Thirteen PFO subjects without a history of embolism were designated as the control group. All PFO and cryptogenic stroke patients were followed up by neurological visits. RESULTS: Compared with controls, PFO patients with acute stroke or TIA more frequently presented with a right-to-left shunt at rest and a higher membrane mobility (P:<0. 05). Patients with these characteristics were considered to be at high risk. During a median follow-up period of 31 months (range, 4 to 58 months), 8 PFO and 18 cryptogenic stroke patients experienced recurrent cerebrovascular events. The cumulative estimate of risk of cerebrovascular event recurrence at 3 years was 4.3% (95% confidence interval [CI], 0% to 10.2%) for "low-risk" PFO patients, 12.5% (95% CI, 0% to 26.1%) for "high-risk" PFO patients, and 16.3% (95% CI, 7. 2% to 25.4%) for cryptogenic stroke patients (high-risk PFO versus low-risk PFO, P:=0.05). CONCLUSIONS: The association of right-to-left shunting at rest and high membrane mobility, as detected by contrast TEE, seems to identify PFO patients with cerebrovascular ischemic events who are at higher risk for recurrent brain embolism.

Aorta↗

PubMed1999

Selective activation of the K(+)(ATP) channel is a mechanism by which sudden death is produced by low-energy chest-wall impact (Commotio cordis).

BACKGROUND: Sudden death due to relatively innocent chest-wall impact has been described in young individuals (commotio cordis). In our previously reported swine model of commotio cordis, ventricular fibrillation (with T-wave strikes) and ST-segment elevation (with QRS strikes) were produced by 30-mph baseball impacts to the precordium. Because activation of the K(+)(ATP) channel has been implicated in the pathogenesis of ST elevation and ventricular fibrillation in myocardial ischemia, we hypothesized that this channel could be responsible for the electrophysiologic findings in our experimental model and in victims of commotio cordis. METHODS AND RESULTS: In the initial experiment, 6 juvenile swine were given 0.5 mg/kg IV glibenclamide, a selective inhibitor of the K(+)(ATP) channel, and chest impact was given on the QRS. The results of these strikes were compared with animals in which no glibenclamide was given. In the second phase, 20 swine were randomized to receive glibenclamide or a control vehicle (in a double-blind fashion), with chest impact delivered just before the T-wave peak. With QRS impacts, the maximal ST elevation was significantly less in those animals given glibenclamide (0.16+/-0.10 mV) than in controls (0.35+/-0.20 mV; P=0.004). With T-wave impacts, the animals that received glibenclamide had significantly fewer occurrences of ventricular fibrillation (1 episode in 27 impacts; 4%) than controls (6 episodes in 18 impacts; 33%; P=0.01). CONCLUSIONS: In this experimental model of commotio cordis, blockade of the K(+)(ATP) channel reduced the incidence of ventricular fibrillation and the magnitude of ST-segment elevation. Therefore, selective K(+)(ATP) channel activation may be a pivotal mechanism in sudden death resulting from low-energy chest-wall trauma in young people during sporting activities.

Adenosine Triphosphate↗

PubMed1999

Three-dimensional reconstruction of the color Doppler-imaged vena contracta for quantifying aortic regurgitation: studies in a chronic animal model.

BACKGROUND: The purpose of this study was to investigate the use of 3-dimensional (3D) reconstruction of color Doppler flow maps to image and extract the vena contracta cross-sectional area to determine the severity of aortic regurgitation (AR) in an animal model. Evaluation of the vena contracta with 2-dimensional imaging systems may not be sufficiently robust to fully characterize this region, which may be asymmetrically shaped. METHODS AND RESULTS: In 6 sheep with surgically induced chronic AR, 18 hemodynamically different states were studied. Instantaneous regurgitant flow rates were obtained by aortic and pulmonary electromagnetic flowmeters (EMFs) as reference standards, and aortic regurgitant effective orifice areas (EOAs) were determined from EMF regurgitant flow rates divided by continuous-wave (CW) Doppler velocities. Composite video data for color Doppler imaging of the aortic regurgitant flows were transferred into a TomTec computer after computer-controlled 180 degrees rotational acquisition. After the 3D data transverse to the flow jet were sectioned, the smallest proximal jet cross section was identified for direct measurement of the vena contracta area. Peak regurgitant flow rates and regurgitant stroke volumes were calculated as the product of these areas and the CW Doppler peak velocities and velocity-time integrals, respectively. There was an excellent correlation between the 3D-derived vena contracta areas and reference EOAs (r=0.99, SEE=0.01 cm2) and between 3D and reference peak regurgitant flow rates and regurgitant stroke volumes (r=0.99, difference=0.11 L/min; r=0.99, difference=1.5 mL/beat, respectively). CONCLUSIONS: 3D-based determination of the vena contracta cross-sectional area can provide accurate quantification of the severity of AR.

Animals↗

PubMed1999

Enhanced visualization of intravascular and left atrial appendage thrombus with the use of a thrombus-targeting ultrasonographic contrast agent (MRX-408A1): In vivo experimental echocardiographic studies.

Echocardiographic evaluation for the recognition of intravascular and left atrial appendage thrombus remains a difficult problem. A thrombus-specific ultrasonographic contrast agent has the potential for an alternative approach for their delineation. The aim of this study was to investigate the usefulness of thrombus-specific contrast agent MRX-408A1 for the detection of acute experimentally created intravascular and intracardiac thrombus. In the first study, we created inferior vena cava thrombus in 9 dogs. With the use of fundamental 2-dimensional echocardiography imaging, we recorded images of the inferior vena cava thrombus at baseline (n = 9), with the thrombus-specific contrast agent MRX-408A1 (n = 9), and with nonspecific contrast agent MRX-113 (n = 6). In the second study, we created a left atrial appendage thrombus in 8 dogs. We imaged left atrial appendage thrombus at baseline and during MRX-113 and MRX-408A1 infusion. Thrombus was successfully created in all dogs in study 1 and in 6 of 8 dogs in study 2. MRX-408A1 produced a visually apparent increase in ultrasonographic contrast enhancement of the thrombus in all cases in which thrombus was found on autopsy. In both studies, MRX-408A1 increased the videointensity of the thrombus significantly compared with baseline images and images obtained during MRX-113 infusion. The size of the visually detectable thrombus on the image was also significantly larger during MRX-408A1 infusion than at baseline and during MRX-113 infusion. These data provide in vivo demonstration of the efficacy of a thrombus-specific contrast agent, MRX-408A1, in the detection of acute intravascular and intracardiac thrombus. It has the potential to improve the diagnostic accuracy of ultrasonography for the detection of acute thrombi at various cardiovascular sites in the clinical setting.

Animals↗

PubMed1999

Flow convergence flow rates from 3-dimensional reconstruction of color Doppler flow maps for computing transvalvular regurgitant flows without geometric assumptions: An in vitro quantitative flow study.

OBJECTIVE: This study was designed to develop and test a 3-dimensional method for direct measurement of flow convergence (FC) region surface area and for quantitating regurgitant flows with an in vitro flow system. BACKGROUND: Quantitative methods for characterizing regurgitant flow events such as flow convergence with 2-dimensional color flow Doppler imaging systems have yielded variable results and may not be accurate enough to characterize those more complex spatial events. METHOD: Four differently shaped regurgitant orifices were studied: 3 flat orifices (circular, rectangular, triangular) and a nonflat one mimicking mitral valve prolapse (all 4 orifice areas = 0.24 cm(2)) in a pulsatile flow model at 8 to 9 different regurgitant flow rates (10 to 50 mL/beat). An ultrasonic flow probe and meter were connected to the flow model to provide reference flow data. Video composite data from the color Doppler flow images of the FC were reconstructed after computer-controlled 180 degrees rotational acquisition was performed. FC surface area (S cm(2)) was calculated directly without any geometric assumptions by measuring parallel sliced flow convergence arc lengths through the FC volume and multiplying each by the slice thickness (2.5 to 3.2 mm) over 5 to 8 slices and then adding them together. Peak regurgitant flow rate (milliliters per second) was calculated as the product of 3-dimensional determined S (cm(2)) multiplied by the aliasing velocity (centimeters per second) used for color Doppler imaging. RESULTS: For all of the 4 shaped orifices, there was an excellent relationship between actual peak flow rates and 3-dimensional FC-calculated flow rates with the direct measurement of the surface area of FC (r = 0.99, mean difference = -7.2 to -0.81 mL/s, % difference = -5% to 0%), whereas a hemielliptic method implemented with 3 axial measurements of the flow convergence zone from 2-dimensional planes underestimated actual flow rate by mean difference = -39.8 to -18.2 mL/s, % difference = -32% to -17% for any given orifice. CONCLUSIONS: Three-dimensional reconstruction of flow based on 2-dimensional color Doppler may add quantitative spatial information, especially for complex flow events. Direct measurement of 3-dimensional flow convergence surface areas may improve accuracy for estimation of the severity of valvular regurgitation.

Blood Flow Velocity↗

PubMed1999

Quantitative assessment of chronic aortic regurgitation with 3-dimensional echocardiographic reconstruction: comparison with electromagnetic flowmeter measurements.

Two-dimensional echocardiography and color Doppler are useful in the qualitative assessment of aortic regurgitation. However, color Doppler planar methods are not accurate in quantifying regurgitant flow, in part because of the complex geometry of aortic regurgitant flow events. Three-dimensional echocardiographic reconstruction is a new technique that provides dynamic 3-dimensional images of intracardiac color flow jets. We sought to determine whether the measurement of aortic regurgitant jet volume by 3-dimensional echocardiography correlated with the true regurgitant volume, measured by electromagnetic flowmeter in vivo, to accurately reflect the severity of aortic regurgitation. We performed volume-rendered 3-dimensional echocardiography in 6 sheep with surgically induced chronic eccentric aortic regurgitation. We obtained a total of 22 aortic regurgitation states by altering loading conditions. Instantaneous regurgitant flow rates were obtained by aortic and pulmonary electromagnetic flowmeters. The maximum aortic regurgitant jet volume by 3-dimensional echocardiography and the maximum jet area by 2-dimensional echocardiography were measured and compared with electromagnetic flowmeter data. By electromagnetic flowmeter, aortic regurgitant flow rate varied from 0.14 to 3.1 L/min (mean 1. 25 +/- 0.78); aortic regurgitant stroke volume varied from 1 to 34 mL/beat (mean 12 +/- 8), and regurgitant fraction varied from 3% to 42% (mean 25% +/- 12%). The maximum jet volume by 3-dimensional echocardiography correlated very well with the aortic regurgitant stroke volume (r = 0.92; P <.0001), with the mean regurgitant flow rate (r = 0.87; P <.0001), and with the regurgitant fraction (r = 0. 87; P <.0001) derived from electromagnetic flowmeter. Both intraobserver and interobserver variability on the measurement of the jet volume by 3-dimensional echocardiography were excellent (r = 0.98; P <.0001 and r = 0.90; P <.001, respectively). The maximum jet area by 2-dimensional echocardiography did not correlate with the aortic regurgitant stroke volume (r = 0.41; P = not significant) and related poorly with the regurgitant fraction (r = 0.52; P <.05) by electromagnetic flowmeter. Dynamic 3-dimensional echocardiography can allow better determination of the geometry of the aortic regurgitant jet and may assist of quantifying the severity of aortic regurgitation.

Animals↗

PubMed1999

Left ventricular apical diastolic collapse: an unusual echocardiographic marker of postoperative cardiac tamponade.

A 37-year-old woman was evaluated for signs and symptoms of cardiac tamponade 11 days after mitral valve replacement and tricuspid valve repair. The transthoracic echocardiogram showed a large, compartmentalized pericardial effusion that resulted in left ventricular apical diastolic collapse. Also noted were right ventricular posterior wall diastolic collapse and hemodynamic findings consistent with cardiac tamponade. This case highlights the atypical echocardiographic findings in patients with pericardial effusions after cardiac surgery.

Adult↗

PubMed1999

Intracardiac echocardiographic guidance during microwave catheter ablation.

The purpose of this study was to explore the potential of intracardiac echocardiography in monitoring lesion formation and assisting with the assessment of ablative lesions using microwave energy. Microwave energy is a promising modality for catheter ablation. Because microwave lesions may have considerable variability in dimension, the ability to assess them may be particularly useful. One hundred twenty-five microwave lesions were created in vitro in ovine left ventricles. Correct assessment of catheter-endocardial contact was possible in virtually all cases. Intracardiac imaging always identified correctly whether or not an ablation was performed. During ablation, gas formation was observed in all instances. Sensitivity, specificity, and predictive values for identification of ablation lesions were 88% to 92%. Although the correlations with pathology for lesion dimensions were relatively poor, intracardiac imaging had a predictive accuracy of 80% to 85% to discriminate small from large lesions. Intracardiac guidance for microwave ablation is useful for verifying tissue-electrode contact, monitoring lesion formation, and localizing lesions. It is also a useful tool for the assessment of lesion size. These attributes, combined with the ability to facilitate transseptal catheterization and to identify complications such as hemopericardium, make intracardiac echocardiography a potentially useful method for guiding microwave ablation of arrhythmic foci.

Animals↗

PubMed1998

New insights and observations in three-dimensional echocardiographic visualization of ventricular septal defects: experimental and clinical studies.

BACKGROUND: The positions, sizes, and shapes of ventricular septal defects (VSDs) can be difficult to assess by 2-dimensional echocardiography (2DE). Volume-rendered 3-dimensional echocardiography (3DE) can provide unique views of VSDs from the left ventricular (LV) side, allowing complete assessment of their circumference and spatial orientations to other anatomic structures. METHODS AND RESULTS: Seventeen experimentally created defects of various locations, sizes, and shapes were imaged and reconstructed in 9 explanted porcine hearts. From an en face projection, major and minor axis diameters of the defects were measured, and these data were compared with direct anatomic measurements. Optimal reconstructions of the VSDs were obtained in all heart specimens, accurately depicting their positions and shapes. The correlations between 3DE and anatomy for the VSD major and minor axis diameters were y=1.0x+0.3 (r=0.88, P<0.001) and y=1.0x-1.4 (r =0.89, P<0.001), respectively. Good agreement between the 2 methods was demonstrated for all measurements. Our experience from the in vitro model was then applied to patient studies. Optimal LV en face reconstructions were obtained in 45 of 51 patients, permitting detailed assessment of the positions, sizes, and shapes of the VSDs. In the 25 patients with comparative surgical measurements, the correlations between 3DE and surgery for the VSD major and minor axis diameters were y =0. 81x+2.1 (r=0.92, P<0.001) and y=0.73x+2.0 (r=0.91, P<0.001), respectively. Good agreement was demonstrated between measurements made by 3DE and those obtained at surgery. CONCLUSIONS: 3DE provides excellent visualization of various types of VSDs. From an LV en face projection, the positions, sizes, and shapes of VSDs can be accurately determined. Such precise imaging will be beneficial for surgical and catheter-based closure of difficult perimembranous and singular or multiple muscular VSDs.

Adolescent↗

PubMed1998

Clinical application of transthoracic volume-rendered three-dimensional echocardiography in the assessment of mitral regurgitation.

Two-dimensional echocardiography (2-DE) and Doppler methods are generally used for assessing mechanisms and severity of mitral regurgitation (MR). Recently, 3-dimensional echocardiography (3-DE) has been applied successfully in various cardiac disorders, but its value in evaluating the mechanism and the severity of MR are not known. We studied 30 patients with MR using 2-DE and 3-DE. Volume-rendered gray-scale 3-DE images of the mitral valve apparatus and MR jets were reconstructed. Maximal volume of the MR jet by 3-DE was compared with mitral regurgitant volume and fraction, regurgitant jet area and the ratio of jet area to left atrial area, and semiquantitative grading derived from 2-DE methods. Our results demonstrated that 3-DE aided in a better depiction of the mitral apparatus and its abnormalities in 70% of the patients. The origin, direction, and morphology of the MR jet were better delineated in 3-DE volumetric display. Quantitative analysis, however, showed only a weak to moderate correlation between 3-DE maximal MR jet volume and 2-DE mitral regurgitant volume (y = 0.5x + 11.4, r = 0.7), regurgitant fraction (y = 0.5x + 8.2, r = 0.65), mitral regurgitant jet area (y = 0.2x + 5, r = 0.51), jet area to left atrial area ratio (y = 0.53x + 7.6, r = 0.54), and semiquantitative grading of MR (y = 9.1x - 1.8, r = 0.74). In conclusion, 3-DE aids in a better understanding of the mechanisms of MR and morphology of the regurgitant jets. Its quantitative ability, when reconstruction of the jet alone is used, may be limited.

Adult↗

PubMed1998

Echocardiographic analysis of regional and global left ventricular shape in Chagas' cardiomyopathy.

Chagas' heart disease is a common form of cardiomyopathy in Latin America and an important cause of cardiac morbidity and mortality there. Left ventricular (LV) apical aneurysm and LV dysfunction are frequent findings in Chagas' cardiomyopathy. Because cardiac shape has important implications for LV function, we sought to characterize regional and global changes in LV geometry in Chagas' heart disease. Quantitative shape analysis was performed on 2-dimensional echocardiograms from 43 patients with Chagas' cardiomyopathy. Regional shape was quantitated by measuring endocardial curvature and global shape was evaluated by Fourier shape analysis of the endocardial contour. Data from 22 age- and sex-matched normal test subjects were used for comparison. Regional shape analysis demonstrated decreased apical curvature (consistent with blunting of normal apical shape) in the group with Chagas' disease compared with controls (apical 2-chamber view: 19 +/- 1 vs 24 +/- 1 [p = 0.0039] at end-diastole and 20 +/- 2 vs 29 +/- 3 [p = 0.0019] at end-systole). Fourier shape power index was decreased in the Chagas' group, consistent with a more spherical ventricle (apical 2-chamber view: 9 +/- 1 vs 17 +/- 2 [p <0.0001] at end-diastole and 12 +/- 1 vs 35 +/- 3 [p <0.0001] at end-systole). Shape changes among the population with Chagas' disease were further evaluated in those with end-diastolic volumes equal to or greater than the median for the group (104 ml) and those < 104 ml. Global shape did not differ between patients with dilated ventricles and those with relatively nondilated ventricles. Diastolic Fourier shape power index = 8 +/- 2 in dilated ventricles compared with 9 +/- 5 in nondilated ventricles (p = 0.53); systolic Fourier shape power index = 10 +/- 2 in dilated versus 14 +/- 2 in nondilated ventricles (p = 0.15) (apical 2-chamber view). In Chagas' cardiomyopathy, LV apical deformation results in disruption of the optimal global prolate-ellipsoid shape, even in patients with relatively preserved LV volumes.

Adult↗

PubMed1998

Three-dimensional echocardiography: clinical relevance and application.

Three-dimensional (3D) echocardiography has recently become a practical reality. It is now practicable to perform 3D echocardiography using transthoracic and transesophageal acoustic windows both in adults and children. The unique image projections that 3D echocardiography yields appear to have enormous potential for displaying intracardiac anatomy in exquisite detail. An important aspect of 3D echocardiography is its ability to supply accurate quantitative data without the use of geometric assumptions. In particular, coupled to contrast ultrasound agents, 3D echocardiography could be valuable in the assessment of myocardial perfusion abnormalities. Early clinical experience suggests that 3D echocardiography is likely to play a valuable role in the evaluation of various cardiac disorders, especially in cardiac surgery. In this section, we will review the use of volume-rendered 3D echocardiography in the diagnosis and assessment of cardiac disorders with particular emphasis on the clinical application of this new methodology.

Echocardiography, Three-Dimensional↗

PubMed1998

An experimental model of sudden death due to low-energy chest-wall impact (commotio cordis)

BACKGROUND: The syndrome of sudden death due to low-energy trauma to the chest wall (commotio cordis) has been described in young sports participants, but the mechanism is unknown. METHODS: We developed a swine model of commotio cordis in which a low-energy impact to the chest wall was produced by a wooden object the size and weight of a regulation baseball. This projectile was thrust at a velocity of 30 miles per hour and was timed to the cardiac cycle. RESULTS: We first studied 18 young pigs, 6 subjected to multiple chest impacts and 12 to single impacts. Of the 10 impacts occurring within the window from 30 to 15 msec before the peak of the T wave on the electrocardiogram, 9 produced ventricular fibrillation. Ventricular fibrillation was not produced by impacts at any other time during the cardiac cycle. Of the 10 impacts sustained during the QRS complex, 4 resulted in transient complete heart block. We also studied whether the use of safety baseballs, which are softer than standard ones, would reduce the risk of arrhythmia. A total of 48 additional animals sustained up to three impacts during the T-wave window of vulnerability to ventricular fibrillation with a regulation baseball and safety baseballs of three degrees of hardness. We found that the likelihood of ventricular fibrillation was proportional to the hardness of the ball, with the softest balls associated with the lowest risk (two instances of ventricular fibrillation after 26 impacts, as compared with eight instances after 23 impacts with regulation baseballs). CONCLUSIONS: This experimental model of commotio cordis closely resembles the clinical profile of this catastrophic event. Whether ventricular fibrillation occurred depended on the precise timing of the impact. Safety baseballs, as compared with regulation balls, may reduce the risk of commotio cordis.

Animals↗

PubMed1998

Three-dimensional echocardiography in ischemic heart disease.

The ability of two-dimensional echocardiography to detect and to evaluate the extent of wall motion abnormalities is limited by the use of few selected, nonparallel, views of the whole left ventricle. This leads to an incomplete appreciation of the spatial relationships between various cardiac structures and inaccuracy in quantitative data as a result of using of geometric assumptions. Dynamic volume-rendered three-dimensional echocardiography has the ability to overcome the above limitations. In this article we review the use of volume-rendered three-dimensional echocardiography in the diagnosis and assessment of ischemic heart disease, including complications related to myocardial infarction.

Echocardiography, Three-Dimensional↗

PubMed1998

Ventricular remodeling in a mouse model of myocardial infarction.

We investigated the suitability of studying ventricular remodeling in a mouse model of myocardial infarction (MI). We performed left coronary ligation (n = 22) or a sham procedure (n = 21) on normal C57BL/6J mice. Six weeks later, animals underwent echocardiography and hemodynamic evaluation. Left ventricular (LV) volume at a common distending pressure was calculated from passive pressure-volume curves. The MI group exhibited lower systolic blood pressure (P < 0.05), higher LV end-diastolic pressure (P < 0.05), and lower peak first derivative of LV pressure (dP/dt, P < 0.05) than the sham group. Mice with moderate (< 40%, n = 11) and large (> or = 40%, n = 11) MIs displayed increased LV mass-to-body weight ratio (P < 0.02 and P < 0.01, respectively, vs. sham group), whereas only the large-MI group exhibited increased right ventricular mass-to-body weight ratio (P < 0.01). LV volumes were increased in the moderate-MI group (P = 0.059 vs. sham group) and to a much greater extent in the large-MI group (P < 0.0001 vs. sham group). The moderate- and large-MI groups also exhibited increases in LV end-diastolic diameter (P < 0.03 and P < 0.0001, respectively, vs. sham group) and LV end-systolic diameter (P < 0.01 and P < 0.0001, respectively, vs. sham group) with decreased fractional shortening (P < 0.01 for both). These data demonstrate ventricular remodeling in a mouse model of MI and confirm the feasibility of quantifying indexes of remodeling in vivo and postmortem. This model will be of particular usefulness when applied to transgenic strains.

Animals↗

PubMed1998

Ultrafast three-dimensional ultrasound: application to carotid artery imaging.

BACKGROUND AND PURPOSE: Three-dimensional (3-D) vascular ultrasound can be expected to improve qualitative evaluation of vessel pathology and to provide quantitative data on vascular morphology and function. The objective of this study was to develop an ultrafast 3-D vascular system and to validate its performance for quantitation of atherosclerosis and assessment of regional arterial distensibility. METHODS: The quantitative analysis of focal atherosclerotic lesions was validated in vitro on 27 phantoms of fibroadipous plaques of known volume (range, 100 to 600 mm3). In vivo reproducibility of plaque volume measurement was tested in 33 patients who had a total of 47 predominantly fibroadipous carotid plaques. Distensibility assessment was validated indirectly through the evaluation of age-related changes in distensibility of common carotid artery in healthy and hypertensive subjects (25 men in each group). RESULTS: The volume of plaque phantoms measured from the 3-D data set showed a very close correlation with the true volume (r=0.99; y=0.96x+12.38; P<0.01), with the mean difference between the 2 measurements being -3.12+/-15.1 mm3. High reproducibility was found for measurement of carotid plaque volume in vivo: the mean difference between measurements from 2 observers for the same data set was 0.60+/-11.2 mm3. Indexes of arterial distensibility decreased with age in healthy population, whereas this relationship was lost in hypertensive subjects. CONCLUSIONS: Ultrafast 3-D ultrasound imaging of carotid artery demonstrates good accuracy and reproducibility for atherosclerotic plaque volume measurements. The system also allows the study of age-related degenerative vascular changes.

Aged↗