Biomedical subjects

Neil L Greenberg

Publications and source records attributed to Neil L Greenberg.

At least 19 recordsLinked to original sources

PubMed2006

Detection of coronary artery stenosis using 40-channel computed tomography with multi-segment reconstruction.

Coronary angiographic studies performed with 16-channel multidetector computer tomographic scanners have demonstrated accurate detection of coronary vessel stenosis but are limited by a significant number of non-evaluable segments. To date, only single-center experience with multidetector computer tomography has been reported. We performed a prospective, blinded study at 2 institutions to determine the feasibility and diagnostic accuracy of coronary angiography using 40-channel multidetector computer tomography with multi-segment reconstruction for the detection of obstructive coronary artery disease (CAD). Multidetector computer tomographic studies were performed in 85 patients who were referred for invasive coronary angiography with clinically suspected CAD. Datasets were analyzed by blinded, independent review. Of 1,145 segments that were suitable for analysis as determined by angiography, 1,045 (91.3%) were evaluable on multidetector computer tomography. Segment-based sensitivity, specificity, and positive and negative predictive values for detecting > or =50% luminal stenoses were 86%, 97%, 75%, and 97%, respectively. The area under the receiver-operating characteristic curves for the detection of > or =50% angiographic stenosis by multidetector computer tomography was 0.94. In a patient-based analysis, the sensitivity, specificity, and positive and negative predictive values for detecting subjects with > or =1 segment with > or =50% stenosis were 98%, 93%, 94% and 93%, respectively. In conclusion, coronary angiography using 40-channel multidetector computer tomography with multi-segment reconstruction accurately detects coronary segments and patients with obstructive CAD, with a small number of non-evaluable cases.

Coronary Angiography↗

PubMed2006

In vivo analysis of the anatomical relationship of coronary sinus to mitral annulus and left circumflex coronary artery using cardiac multidetector computed tomography: implications for percutaneous coronary sinus mitral annuloplasty.

OBJECTIVES: We sought to determine the in vivo anatomical relationships between mitral annulus (MA) and coronary sinus (CS) as well as CS and left circumflex coronary artery using cardiac computed tomography. BACKGROUND: Percutaneous treatment of mitral regurgitation (MR) by annuloplasty via CS is under development. Success of such treatment depends on the close anatomical proximity of the MA to the CS. The in vivo data regarding this anatomical relationship in humans are scant. We investigated this relationship using contrast multidetector computed tomography. METHODS: We studied 25 normal individuals and 11 patients with severe MR (3 to 4+) due to mitral valve prolapse. Separation between MA and CS was measured in standard planes, in 4-chamber (4C), 2-chamber (2C), and 3-chamber views. Distance from ostium of CS to the intersection with left circumflex (LCX), and anatomical relation of LCX and CS were determined using 3-dimensional mapping (Philips Brilliance, Philips Medical Systems, Amsterdam, the Netherlands). RESULTS: There was significant variance of CS to MA separation at all planes. Separation of CS and MA was increased in lateral location (4C) and decreased in posterior location (2C) in the MR group with increase in MA size. Left circumflex artery crossed between CS and MA in 80% of patients. The LCX crossed CS at a variable distance from the ostium of CS (86.5 +/- 21 mm, range 37 to 123 mm) CONCLUSIONS: There is significant variability in the relation of CS to MA in humans. Coronary sinus to MA distance increases in patients with severe MR and annular dilation, mainly in the posterolateral location. The left circumflex crosses under the CS the majority of times, but with a significant variability in the location where it crosses the CS. These anatomical features should be taken into consideration while selecting percutaneous treatment strategies for mitral valve repair.

Adult↗

PubMed2006

Detection of transplant coronary artery disease using multidetector computed tomography with adaptative multisegment reconstruction.

OBJECTIVES: This study sought to determine whether multidetector computed tomography (MDCT) may be able to detect occlusive coronary disease in transplanted hearts. BACKGROUND: In heart transplant recipients, asymptomatic coronary disease requiring frequent surveillance commonly develops. Recent advancements in MDCT allow for noninvasive assessment of the coronary vessels. METHODS: Electrocardiogram-gated contrast-enhanced MDCT scans (16 x 0.75-mm detectors, 420 ms rotation, 100 ml contrast) with multisegment reconstruction were performed on 54 transplant recipients within 6 +/- 11 days of quantitative coronary angiography (QCA). Heart rate at the time of the scan was 90 +/- 11 beats/min. Coronary arterial segments >1.5 mm in diameter were analyzed by independent investigators. RESULTS: There was a good correlation between MDCT and QCA percent stenosis (r = 0.75, p < 0.01, SEE = 15%). Of the 791 segments identified by QCA, 754 (95%) were analyzable by MDCT. The sensitivity, specificity, and positive and negative predictive values of MDCT compared with QCA for the detection of segments with significant (>50%) stenosis were 86%, 99%, 81%, and 99%, respectively. The MDCT correctly identified 15 of the 16 (94%) transplant patients classified by QCA as having occlusive coronary artery disease and 29 of the 37 patients without significant stenosis (78%). In 1 patient who received intravenous beta-blockers, transient bradycardia requiring temporary pacing developed, but there were no other complications. CONCLUSIONS: Detection of occlusive coronary disease in heart transplant recipients with elevated resting heart rate by MDCT is feasible using multicycle reconstruction. The need for surveillance invasive coronary angiography in transplant recipients might be mitigated by use of MDCT.

Adult↗

PubMed2006

Three-dimensional geometry of the tricuspid annulus in healthy subjects and in patients with functional tricuspid regurgitation: a real-time, 3-dimensional echocardiographic study.

BACKGROUND: Most rings currently used for tricuspid valve annuloplasty are formed in a single plane, whereas the actual tricuspid annulus (TA) may have a nonplanar or 3-dimensional (3D) structure. The purpose of this study was therefore to investigate the 3D geometry of the TA in healthy subjects and in patients with functional tricuspid regurgitation (TR). METHODS AND RESULTS: This study consisted of 15 healthy subjects and 16 patients with functional TR who had real-time 3D echocardiography. With our customized software, 8 points along the TA were determined with the rotated plane around the axis at 45 degrees intervals. The TA was traced during a cardiac cycle. The distance between diagonals connecting 2 points was measured. The height was defined as the distance from the plane determined by least-squares regression analysis at all 8 points. Both the maximum (7.5+/-2.1 versus 5.6+/-1.0 cm2/m2) and minimum (5.7+/-1.3 versus 3.9+/-0.8 cm2/m2) TA areas in patients with TR were larger than those in healthy subjects (both P<0.01). Healthy subjects had a nonplanar-shaped TA with homogeneous contraction. The posteroseptal portion was the lowest toward the apex from the right atrium, and the anteroseptal portion was the highest. In patients with functional TR, the TA was dilated in the septal to lateral direction, resulting in a more circular shape than in healthy subjects. A similar 3D pattern was observed in patients with TR, but it was more planar than that in healthy subjects. CONCLUSIONS: Real-time 3D echocardiography showed a complicated 3D structure of the TA, which appeared to be different from the "saddle-shaped" mitral annulus, suggesting an annuloplasty for TR different from that for mitral regurgitation.

Adult↗

PubMed2006

Use of tissue Doppler imaging to guide tube current modulation in cardiac multidetector computed tomographic angiography.

In multidetector computed tomographic coronary angiography, strategies to minimize effective radiation dose (ERD) are urgently needed. Prospective tube current modulation (TCM) allows a decrease in ERD, although it may limit reconstruction options. We sought to determine if tissue Doppler imaging (TDI) by echocardiography could predict an optimal phase for multidetector computed tomography and be used to guide TCM. Echocardiographic studies were performed in 94 patients immediately before multidetector computed tomography (83% men; mean 60 +/- 11 years of age, mean body mass index 27.7+/-4.1 kg/m2) and identified the most quiescent phase of the cardiac cycle within the atrioventricular groove. In 40 patients, prospective TCM was programmed according to TDI (TCM(TDI) group); 54 patients underwent multidetector computed tomography without TCM (no-TCM). In 25 patients assigned to the TCM(TDI) group, multidetector computed tomograms were correlated with invasive quantitative coronary angiograms to ensure maintenance of diagnostic accuracy. Optimal phase determined by TDI was 71 +/- 11%, with a distinct bi-modal distribution. Compared with no-TCM, effective radiation dose was decreased by 42% in the TCM(TDI) group (6.6 +/- 1.2 vs 11.4 +/- 2.2 mSv, p < 0.0001). Only 8 segments (3%) were unevaluable due to motion artifact. In 296 segments, sensitivity, specificity, and positive and negative predictive values to detect lesions > 50% by multidetector computed tomography were 92%, 94%, 65%, and 99%, respectively. There was good correlation between quantitative coronary angiography and multidetector computed tomography for absolute degree of stenosis (r = 0.70, p < 0.0001). In conclusion, TDI is a useful tool to guide prospective TCM in multidetector computed tomography. ERD in multidetector computed tomography may be significantly decreased using this technique while maintaining excellent image quality.

Cardiac Catheterization↗

PubMed2006

Maturational and adaptive modulation of left ventricular torsional biomechanics: Doppler tissue imaging observation from infancy to adulthood.

BACKGROUND: Left ventricular (LV) torsional deformation, based in part on the helical myocardial fiber architecture, is an important component of LV systolic and diastolic performance. However, there is no comprehensive study describing its normal development during childhood and adult life. METHODS AND RESULTS: Forty-five normal subjects (25 children and 20 adults; aged 9 days to 49 years; divided into 5 groups: infants, children, adolescents, and young and middle-age adults) underwent assessment of LV torsion and untwisting rate by Doppler tissue imaging. LV torsion increased with age, primarily owing to augmentation in basal clockwise rotation during childhood and apical counterclockwise rotation during adulthood. Although LV torsion and untwisting overall showed age-related increases, when normalized by LV length, they showed higher values in infancy and middle age. The proportion of untwisting during isovolumic relaxation was lowest in infancy, increased during childhood, and leveled off thereafter, whereas peak untwisting performance (peak untwisting velocity normalized by peak LV torsion) showed a decrease during adulthood. CONCLUSIONS: We have shown the maturational process of LV torsion in normal subjects. Net LV torsion increases gradually from infancy to adulthood, but the determinants of this were different in the 2 age groups. The smaller LV isovolumic untwisting recoil during infancy and its decline in adulthood may suggest mechanisms for alterations in diastolic function.

Adaptation, Physiological↗

PubMed2006

Enhanced ventricular untwisting during exercise: a mechanistic manifestation of elastic recoil described by Doppler tissue imaging.

BACKGROUND: The cascade of events by which early diastolic left ventricular (LV) filling increases with exercise is not fully elucidated. Doppler tissue imaging (DTI) can detect myocardial motion, including torsion, whereas color M-mode Doppler (CMM) can quantify LV intraventricular pressure gradients (IVPGs). METHODS AND RESULTS: Twenty healthy volunteers underwent echocardiographic examination with DTI at rest and during submaximal supine bicycle exercise. We assessed LV long-/short-axis function, torsion, volume, inflow dynamics, and early diastolic IVPG derived from CMM data. LV torsion and untwisting velocity increased with exercise (torsion, 11+/-4 degrees to 24+/-8 degrees ; untwisting velocity, -2.0+/-0.7 to -5.6+/-2.3 rad/s) that was associated with an increase in IVPG (1.4+/-0.5 to 3.7+/-1.2 mm Hg). Untwisting in normal subjects occurred during isovolumic relaxation and early filling, significantly before long-axis lengthening or radial expansion. The clinical feasibility of this method was tested in 7 patients with hypertrophic cardiomyopathy (HCM); torsion was higher at rest but did not increase with exercise (16+/-4 degrees to 14+/-6 degrees), whereas untwisting was delayed and unenhanced (-1.6+/-0.8 to -2.3+/-1.2 rad/s). In concert, IVPG was similar at rest (1.2+/-0.3 mm Hg), but the exercise response was blunted (1.6+/-0.8 mm Hg). In normal subjects and HCM patients, there was a similar linear relation between IVPG and untwisting rate, with an overall correlation coefficient of r=0.75 (P<0.0001). CONCLUSIONS: LV untwisting appears to be linked temporally with early diastolic base-to-apex pressure gradients, enhanced by exercise, which may assist efficient LV filling, an effect that appears blunted in HCM. Thus, LV torsion and subsequent rapid untwisting appear to be manifestations of elastic recoil, critically linking systolic contraction to diastolic filling.

Adult↗

PubMed2006

Scaling of diastolic intraventricular pressure gradients is related to filling time duration.

In early diastole, pressure is lower in the apex than in the base of the left ventricle (LV). This early intraventricular pressure difference (IVPD) facilitates LV filling. We assessed how LV diastolic IVPD and intraventricular pressure gradient (IVPG), defined as IVPD divided by length, scale to the heart size and other physiological variables. We studied 10 mice, 10 rats, 5 rabbits, 12 dogs, and 21 humans by echocardiography. Color Doppler M-mode data were postprocessed to reconstruct IVPD and IVPG. Normalized LV filling time was calculated by dividing filling time by RR interval. The relationship between IVPD, IVPG, normalized LV filling time, and LV end-diastolic volume (or mass) as fit to the general scaling equation Y = kM beta, where M is LV heart size parameter, Y is a dependent variable, k is a constant, and beta is the power of the scaling exponent. LV mass varied from 0.049 to 194 g, whereas end-diastolic volume varied from 0.011 to 149 ml. The beta values relating normalized LV filling time with LV mass and end-diastolic volume were 0.091 (SD 0.011) and 0.083 (SD 0.009), respectively (P < 0.0001 vs. 0 for both). The beta values relating IVPD with LV mass and end-diastolic volume were similarly significant at 0.271 (SD 0.039) and 0.243 (SD 0.0361), respectively (P < 0.0001 vs. 0 for both). Finally, beta values relating IVPG with LV mass and end-diastolic volume were -0.118 (SD 0.013) and -0.104 (SD 0.011), respectively (P < 0.0001 vs. 0 for both). As a result, there was an inverse relationship between IVPG and normalized LV filling time (r = -0.65, P < 0.001). We conclude that IVPD decrease, while IVPG increase with decreasing animal size. High IVPG in small mammals may be an adaptive mechanism to short filling times.

Adult↗

PubMed2006

Intraventricular pressure gradients in left ventricular aneurysms determined by color M-mode Doppler method: an animal study.

BACKGROUND: Left ventricular aneurysm (LVA) may affect diastolic intraventricular blood flow. Color M-mode (CMM) Doppler flow propagation patterns are abnormal in the presence of apical aneurysms. The aim of this study was to validate the accuracy of CMM echocardiography for assessing the existence and size of LVA and to determine the intraventricular pressure gradient in LVA. METHODS: CMM of the transmitral inflow in early diastole was obtained from the apical 4-chamber view in 19 sheep. The presence of the break point where the velocity decreased abruptly in the mitral inflow (point D) was determined and the distance between the apex and point D was measured. The intraventricular pressure difference between the base and the apex was measured by a catheter while it was calculated using CMM with the Euler equation. RESULTS: The presence of the break point D showed 84% sensitivity and 100% specificity for determining the existence of an LVA. Distance between the apex and point D correlated well with scar size. Catheter- and CMM-derived intraventricular pressure difference correlated and agreed well (y = 1.0 x -0.2, r = 0.94). CONCLUSIONS: The point of abrupt decrease in propagation velocity of the CMM recording indicated the presence and size of LVA. Intraventricular pressure gradients were determined noninvasively by CMM echocardiography with reasonable accuracy.

Animals↗

PubMed2005

Relationship among diastolic intraventricular pressure gradients, relaxation, and preload: impact of age and fitness.

Diastolic intraventricular pressure gradients (IVPGs) are a measure of the ability of the ventricle to facilitate its filling using diastolic suction. We assessed 15 healthy young but sedentary subjects, aged <50 yr (young subjects; age, 35 +/- 9 yr); 13 healthy but sedentary seniors, aged >65 yr with known reductions in ventricular compliance (elderly sedentary subjects; age, 70 +/- 4 yr); and 12 master athletes, aged >65 yr, previously shown to have preserved ventricular compliance (elderly fit subjects; age, 68 +/- 3 yr). Pulmonary capillary wedge pressure (PCWP) and echocardiography measurements were performed at baseline, during load manipulation by lower body negative pressure at -15 and -30 mmHg, and after saline infusion of 10 and 20 ml/kg (elderly) or 15 and 30 ml/kg (young). IVPGs were obtained from color M-mode Doppler echocardiograms. Baseline IVPGs were lower (1.2 +/- 0.4 vs. 2.4 +/- 0.7 mmHg, P < 0.0001), and the time constant of pressure decay (tau(0)) was longer (60 +/- 10 vs. 46 +/- 6 ms, P < 0.0001) in elderly sedentary than in young subjects, with no difference in PCWP. Although PCWP changes during load manipulations were similar (P = 0.70), IVPG changes were less prominent in elderly sedentary than in young subjects (P = 0.02). Changes in stroke volume and IVPGs during loading manipulations correlated (r = 0.96, P = 0.0002). PCWP and tau(0) were strong multivariate correlates of IVPGs (P < 0.001, for both). IVPG response to loading interventions in elderly sedentary and elderly fit subjects was similar (P = 0.33), despite known large differences in ventricular compliance. The ability to regulate IVPGs during changes in preload is impaired with aging. Preserving ventricular compliance during aging by lifelong exercise training does not prevent this impairment.

Adult↗

PubMed2005

Differences in left ventricular long-axis function from mice to humans follow allometric scaling to ventricular size.

While the heart size maintains a constant proportion to body size, heart function parameters, such as heart rate and cardiac output, show a more complex scaling pattern. How these phenomena affect the long-axis left ventricular (LV) function is unknown. We studied 10 mice, 15 rats, 6 rabbits, 8 mongrel dogs and 38 human volunteers. Doppler tissue echocardiography data were postprocessed to reconstruct mitral annulus (MA) peak systolic velocity and displacement. The relationship between MA peak velocity, MA displacement and LV ejection time, and LV end-diastolic volume (and mass) were fit to an allometric (power-law) equation Y=kMbeta. LV mass varied from 0.062 to 255 g, while end-diastolic volume varied from 0.014 to 205 ml. beta values of the relation between LV ejection time and LV end-diastolic volume and mass were 0.247+/-0.017 and 0.267+/-0.018, respectively. beta values of the relationship between MA displacement and LV end-diastolic volume and mass were 0.358+/-0.047 and 0.390+/-0.051 (P<0.023 versus beta of LV ejection time). beta values of the relationship between MA peak systolic velocity and LV end-diastolic volume and mass were 0.096+/-0.012 and 0.100+/-0.013, respectively (P<0.0001 versus 0). Finally, beta values of the relationship between the long-to-short axis displacement ratio and LV end-diastolic volume and mass were 0.077+/-0.017 and 0.086+/-0.019 (P<0.0001 versus 0). We conclude that MA velocity, displacement, and long-to-short axis displacement ratio scale allometrically to heart size. This reduces the relative long-axis contribution to heart function in small mammals.

Animals↗

PubMed2005

Measurement of ventricular torsion by two-dimensional ultrasound speckle tracking imaging.

OBJECTIVES: We sought to examine the accuracy/consistency of a novel ultrasound speckle tracking imaging (STI) method for left ventricular torsion (LVtor) measurement in comparison with tagged magnetic resonance imaging (MRI) (a time-domain method similar to STI) and Doppler tissue imaging (DTI) (a velocity-based approach). BACKGROUND: Left ventricular torsion from helically oriented myofibers is a key parameter of cardiac performance but is difficult to measure. Ultrasound STI is potentially suitable for measurement of angular motion because of its angle-independence. METHODS: We acquired basal and apical short-axis left ventricular (LV) images in 15 patients to estimate LVtor by STI and compare it with tagged MRI and DTI. Left ventricular torsion was defined as the net difference of LV rotation at the basal and apical planes. For the STI analysis, we used high-frame (104 +/- 12 frames/s) second harmonic two-dimensional images. RESULTS: Data on 13 of 15 patients were usable for STI analysis, and LVtor profile estimated by STI strongly correlated with those by tagged MRI (y = 0.95x + 0.19, r = 0.93, p < 0.0001, analyzed by repeated-measures regression models). The STI torsional velocity profile also correlated well with that by the DTI method (y = 0.79x + 2.4, r = 0.76, p < 0.0001, by repeated-measures regression models) with acceptable bias. CONCLUSIONS: The STI estimation of LVtor is concordant with those analyzed by tagged MRI (data derived from tissue displacement) and also showed good agreement with those by DTI (data derived from tissue velocity). Ultrasound STI is a promising new method to assess LV torsional deformation and may make the assessment more available in clinical and research cardiology.

Echocardiography↗

PubMed2005

Relationship of diastolic intraventricular pressure gradients and aerobic capacity in patients with diastolic heart failure.

We sought to elucidate the relationship between diastolic intraventricular pressure gradients (IVPG) and exercise tolerance in patients with heart failure using color M-mode Doppler. Diastolic dysfunction has been implicated as a cause of low aerobic potential in patients with heart failure. We previously validated a novel method to evaluate diastolic function that involves noninvasive measurement of IVPG using color M-mode Doppler data. Thirty-one patients with heart failure and 15 normal subjects were recruited. Echocardiograms were performed before and after metabolic treadmill stress testing. Color M-mode Doppler was used to determine the diastolic propagation velocity (Vp) and IVPG off-line. Resting diastolic function indexes including myocardial relaxation velocity, Vp, and E/Vp correlated well with VO2max (r = 0.8, 0.5, and -0.5, respectively, P < 0.001 for all). There was a statistically significant increase in Vp and IVPG in both groups after exercise, but the change in IVPG was higher in normal subjects compared with patients with heart failure (2.6 +/- 0.8 vs. 1.1 +/- 0.8 mmHg, P < 0.05). Increase in IVPG correlated with peak VO2max (r = 0.8, P < 0.001) and was the strongest predictor of exercise capacity. Myocardial relaxation is an important determinant of exercise aerobic capacity. In heart failure patients, impaired myocardial relaxation is associated with reduced diastolic suction force during exercise.

Adolescent↗

PubMed2005

Assessment of left ventricular torsional deformation by Doppler tissue imaging: validation study with tagged magnetic resonance imaging.

BACKGROUND: Left ventricular (LV) torsional deformation is a sensitive index for LV performance but difficult to measure. The present study tested the accuracy of a novel method that uses Doppler tissue imaging (DTI) for quantifying LV torsion in humans with tagged magnetic resonance imaging (MRI) as a reference. METHODS AND RESULTS: Twenty patients underwent DTI and tagged MRI studies. Images of the LV were acquired at apical and basal short-axis levels to assess LV torsion. We calculated LV rotation by integrating the rotational velocity, determined from DTI velocities of the septal and lateral regions, and correcting for the LV radius over time. LV torsion was defined as the difference in LV rotation between the 2 levels. DTI rotational and torsional profiles throughout systole and diastole were compared with those by tagged MRI at isochronal points. Rotation and torsion by DTI were closely correlated with tagged MRI results during systole and early diastole (apical and basal rotation, r=0.87 and 0.90, respectively; for torsion, 0.84; P<0.0001, by repeated-measures regression models). Maximal torsion showed even better correlation (r=0.95, P<0.0001). CONCLUSIONS: The present study has shown that DTI can quantify LV torsional deformation over time. This novel method may facilitate noninvasive quantification of LV torsion in clinical and research settings.

Aortic Valve Insufficiency↗

PubMed2005

Automated mitral annular tracking: a novel method for evaluating mitral annular motion using two-dimensional echocardiography.

We developed an automated mitral annular tracking method based on a digital processing of high frame rate cineloop images of 2-dimensional echocardiography. In this study, its feasibility and accuracy was validated in 11 healthy volunteers and 16 patients with left ventricular (LV) dysfunction. The mitral annular excursion measured by automated mitral annular tracking agreed well with that measured by 3-dimensional echocardiography and correlated with LV ejection fraction. The longitudinal mitral annular excursion was reduced whereas the radial one was preserved for patients with LV dysfunction compared with control subjects. The novel automated mitral annular tracking method is clinically feasible and has potential capability to quantify the comprehensive mitral annular motion for evaluating LV function in a clinical setting.

Adult↗

PubMed2005

Planimetric assessment of anatomic valve area overestimates effective orifice area in bicuspid aortic stenosis.

BACKGROUND: Although the continuity equation remains the noninvasive standard, planimetry using transesophageal echocardiography is often used to assess valve area for patients with aortic stenosis (AS). Not uncommonly, however, anatomic valve area (AVAA) obtained by planimetry overestimates continuity-derived effective valve area (AVAE) in bicuspid AS. METHODS: Transthoracic Doppler and transesophageal echocardiography were performed to obtain AVAE and AVAA in 31 patients with bicuspid AS (age 61 +/- 11 years) and 22 patients with degenerative tricuspid AS (age 71 +/- 13 years). Aortic root and left ventricular outflow tract dimensions and the directional angle of the stenotic jet were assessed in all patients. Using these data, a computational fluid dynamics model was constructed to test the effect of these variables in determining the relationship between AVAE and AVAA. RESULTS: For patients with tricuspid AS, the correlation between AVAA (1.15 +/- 0.36 cm2) and AVAE (1.13 +/- 0.46 cm2) was excellent (r = 0.91, P < .001, Delta = 0.02 +/- 0.21 cm2). However, AVAA was significantly larger (1.19 +/- 0.35 cm2) than AVAE (0.89 +/- 0.29 cm2) in the bicuspid AS group (r = 0.71, P < .001, Delta = 0.29 +/- 0.25 cm2). Computer simulation demonstrated that the observed discrepancy related to jet eccentricity. CONCLUSION: For a given anatomic orifice, functional severity tends to be greater in bicuspid AS than in tricuspid AS. This appears to be primarily related to greater jet eccentricity and less pressure recovery.

Anatomy, Cross-Sectional↗

PubMed2005

The accuracy of left ventricular mass determined by real-time three-dimensional echocardiography in chronic animal and clinical studies: a comparison with postmortem examination and magnetic resonance imaging.

Real-time 3-dimensional echocardiography (RT3DE), 2-dimensional echocardiography (2DE), and M-mode echocardiography were performed in 28 sheep with cardiac pathologies and 27 patients with heart disease to demonstrate the superiority of RT3DE over M-mode and 2DE for the determination of left ventricular mass. Postmortem examination and magnetic resonance imaging were used as a reference standard for the animal and clinical studies, respectively. In the animal study, the highest concordance correlation (0.92) was obtained between the actual weight of left ventricular mass and that estimated by RT3DE (0.69 for 2DE and 0.77 for M-mode, P < .001). In the clinical study, RT3DE also provided the best concordance correlation with left ventricular mass determined by magnetic resonance imaging (0.91 for RT3DE, 0.83 for 2DE, and 0.38 for M-mode; P < .0001).

Animals↗

PubMed2005

Non-invasive evaluation of orthotopic heart transplant rejection by echocardiography.

BACKGROUND: Heart transplant recipients require frequent myocardial biopsies to screen for acute rejection. The purpose of this study was to identify demographic and echocardiographic factors associated with transplant rejection and develop a predictive model, which may reduce the number of cardiac biopsies. METHODS: From January 1998 to December 2001, we performed 406 echocardiographic studies on 264 heart transplant patients who had biopsies performed on the same day. Two-dimensional, pulsed and tissue Doppler echocardiographic variables were compared between patients with and without rejection, and their predictive ability for detecting rejection was determined by uni- and multivariate analyses. RESULTS: In 268 biopsies there was no significant rejection (ISHLT Grade <==II), whereas 138 showed rejection (ISHLT Grade > or =IIIa). By multivariate analysis, pericardial effusion, isovolumic relaxation time (IVRT) <90 milliseconds and mitral inflow E/A ratio >1.7, diameter of inferior vena cava and duration of pulmonary vein atrial reversal were independently associated with rejection. Because the odds ratios were similar for all 5 predictors, a simplified model was developed based on the sum of the number of abnormal predictors present (0 to 5). The probability of rejection increased from 15.9%, in the absence of any predictor, to 39.7%, 52.0% and 71.1%, if 1, 2 or 3 predictors were present, respectively. CONCLUSIONS: Recipient age, pericardial effusion, IVRT and ratio of pulsed Doppler E/A are significant predictors of acute cardiac allograft rejection. However, no single predictor or combination of predictors were powerful enough to eliminate surveillance endomyocardial biopsies.

Adult↗