Implementation of a Myocardial Perfusion Imaging Risk Algorithm to Inform Appropriate Downstream Invasive Testing and Treatment.

BACKGROUND: To risk stratify patients undergoing single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) in accordance with appropriate use criteria for referral to coronary angiography, we developed a risk classification algorithm incorporating appropriate use criteria-defined risk features. We evaluated the association between this algorithm with downstream angiography, revascularization, and all-cause mortality. METHODS: We studied consecutive patients who underwent SPECT-MPI from January 1, 2015, to December 31, 2017, and assigned a scan risk of low, intermediate, high, or indeterminate. With this stratification, we assessed referral for angiography and revascularization within 3 months of SPECT-MPI and intermediate-term mortality. RESULTS: Among 12 799 patients, the mean age was 66 years, and a majority were men (56.8%). Most patients were low risk (83.6%) followed by intermediate (9.9%) and high risk (5.2%). Compared with low-risk patients, intermediate- and high-risk patients were more frequently referred for angiography (14.8% and 13.6% versus 2.0%; P<0.001) and revascularization (7.7% and 6.8% versus 0.7%; P<0.001). In 1008 propensity-matched patients, scan risk was independently associated with angiography after adjustment for ischemia, scar, or stress ejection fraction. At a mean follow-up of 2.3 years, mortality was higher with increased scan risk (high, 10.4%; intermediate, 7.1%; low, 4.1%; P<0.001). Compared with low scan risk, intermediate (hazard ratio, 1.37 [95% CI, 1.09-1.72]; P=0.008) and high scan risk (hazard ratio, 1.98 [95% CI, 1.53-2.56]; P<0.001) were associated with mortality in multivariable analysis. Similar findings were observed for those undergoing pharmacological and exercise SPECT-MPI with comparatively worse prognosis among pharmacological patients. CONCLUSIONS: This appropriate use criteria-derived risk classification algorithm for SPECT-MPI guided referral for coronary angiography and revascularization and was significantly associated with mortality. This algorithm may serve as an important tool to reaffirm appropriate use criteria and direct management of patients with stable ischemic heart disease undergoing stress testing.

Coupled pacing improves left ventricular function during simulated atrial fibrillation without mechanical dyssynchrony.

AIMS: Electrical stimulation [coupled pacing (CP)] applied near the end of the T-wave is able to create a retrograde activation of the atrioventricular (AV) node in turn to prevent rapid ventricular conduction during atrial fibrillation (AF). The impact of this pacing modality associated with cardiac resynchronization therapy (CRT) has been evaluated in the present experimental study. METHODS AND RESULTS: After inducing AF by rapid pacing in six dogs, we applied the following pacing modalities: rapid right ventricular (RV) pacing, rapid CRT, CRT with an additional RV paced beat (CP) at a specific delay (CRT + CP), and CRT with vagal stimulation (CRT-VS). Left ventricular (LV) pressure recordings and echocardiography for 2D strain analysis were performed. CRT + CP reduced the ventricular response rate and increased the LV systolic pressure and cardiac output compared with CRT alone (136 +/- 6 vs. 86 +/- 13 mmHg, P < 0.05 and 2.0 +/- 0.4 vs.1.2 +/- 0.1, P < 0.05 L/m, respectively). Compared with CRT-VS, CRT + CP increased the LV ejection fraction (LVEF = 51 +/- 10 vs. 28 +/- 4%, P < 0.05), peak global circumferential strain (-17 +/- 2 vs. -11 +/- 3%), and diastolic filling time (49 +/- 6 vs. 28 +/- 3%, P < 0.02) suggesting beneficial effects of CP beyond rate control. CRT + CP did not result in increased dyssynchrony [CRT (8.3 +/- 2%) vs. CRTCP (8.4 +/- 3%, P = NS)]. CONCLUSION: CRT + CP effectively reduces ventricular contractile rate and leads to an increase in systolic and diastolic performance without inducing mechanical dyssynchrony.

Impact of left ventricular volume/mass ratio on diastolic function.

AIMS: To assess the impact of left ventricular (LV) volume/mass ratio on diastolic function parameters in subjects with dilated cardiomyopathy (DCM) or hypertrophic cardiomyopathy (HCM) and healthy controls. METHODS AND RESULTS: We performed echocardiography in 44 healthy controls, 35 HCM subjects, 29 DCM subjects with narrow QRS complex (DCM-n), and 27 DCM subjects with wide QRS complex (DCM-w). Mitral annulus velocity (E(a)) and transmitral E-wave velocity were used to estimate time constant of isovolumic pressure decay (tau). LV flow propagation velocity (V(p)) and early intraventricular pressure gradient (IVPG) were derived from colour M-mode of LV inflow. We calculated LV twist and peak untwisting rate (UntwR) by speckle tracking. Mean LV volume/mass ratio was 0.34 +/- 0.09 mL/g in healthy controls, 0.15 +/- 0.06 mL/g in HCM, 0.6 +/- 0.2 mL/g in DCM-n, and 0.8 +/- 0.3 mL/g in DCM-w patients (P < 0.001 for all groups). Resting LV ejection fractions were 63 +/- 7, 64 +/- 8, 31 +/- 8, and 26 +/- 8%, respectively (P < 0.01 vs. controls for DCM groups). In a multivariate analysis, LV volume/mass ratio remained a strong independent predictor of V(p) (P < 0.001), IVPG (P = 0.009), and UntwR (P < 0.001) but not for E(a) (P = 0.25). CONCLUSION: LV volume/mass ratio had influences on diastolic function parameters independent of intrinsic diastolic function and filling pressures. It should be considered when assessing patients suspected of LV diastolic dysfunction.

Longitudinal strain delay index by speckle tracking imaging: a new marker of response to cardiac resynchronization therapy.

BACKGROUND: In heart failure patients with left ventricular dyssynchrony, contractility in delayed segments does not fully contribute to end-systolic function. We quantified this reserve of contraction related to mechanical dyssynchrony to predict response to cardiac resynchronization therapy by the strain delay index, which was defined as the sum of the difference between peak and end-systolic strain across 16 segments. METHODS AND RESULTS: In 100 heart failure patients (ejection fraction=26+/-9%, QRS=154+/-29 ms, 94% in New York Heart Association class III), we studied left ventricular dyssynchrony before cardiac resynchronization therapy by the strain delay index using longitudinal strain by 2D speckle tracking and by the SD of time to peak myocardial velocity in 12 segments. The optimal cutoff value of the strain delay index to predict response to cardiac resynchronization therapy was determined in a retrospective group (n=65) and then confirmed in a validation group (n=35). Left ventricular end-systolic volume reduction at 3 months >15% (responder) occurred in 64 of 100 patients. In the retrospective group, the strain delay index but not the SD of time to peak myocardial velocity was greater in responders (n=42/65) than nonresponders (35+/-8% versus 19+/-7%, P<0.0001), and the optimal cutoff value to identify response to cardiac resynchronization therapy was 25%. In the validation group, strain delay index > or =25% identified 82% (18/22) of responders and 92% (12/13) of nonresponders. Among the entire population (n=100), strain delay index correlated with reverse remodeling in both the ischemic (r=-0.68, P<0.0001) and nonischemic (r=-0.68, P<0.0001) population. CONCLUSIONS: Use of the strain delay index with longitudinal strain by speckle tracking has a strong predictive value for predicting response to cardiac resynchronization therapy in both ischemic and nonischemic patients.

Non-invasive assessment of left ventricular relaxation during atrial fibrillation using mitral flow propagation velocity.

AIMS: To elucidate the usefulness of the early diastolic mitral flow propagation velocity (V(p)) obtained from colour M-mode Doppler for non-invasively assessing left-ventricular (LV) relaxation during atrial fibrillation (AF). METHODS AND RESULTS: Ten healthy adult dogs were studied to correlate V(p) with the invasive minimum value of the first derivative of LV pressure decay (dP/dt(min)) and the time constant of isovolumic LV pressure decay (tau) at baseline, during rapid and slow AF, and during AF after inducing myocardial infarction. There were significant positive and negative curvilinear relationships between V(p) and dP/dt(min) and tau, respectively, during rapid AF. After slowing the ventricular rate, the average value of V(p) increased, while dP/dt(min) increased and tau decreased. After inducing myocardial infarction, the average value of V(p) decreased, while dP/dt(min) decreased and tau increased. CONCLUSION: The non-invasively obtained V(p) evaluates LV relaxation even during AF regardless of ventricular rhythm or the presence of pathological changes.

Geometry of the proximal isovelocity surface area in mitral regurgitation by 3-dimensional color Doppler echocardiography: difference between functional mitral regurgitation and prolapse regurgitation.

BACKGROUND: The geometry of the proximal isovelocity surface area (PISA) of functional mitral regurgitation (MR), which is conventionally assumed to be a hemisphere, remains to be clarified. We investigated the 3-dimensional (3D) geometry of PISA of functional MR as opposed to that of MR due to mitral valve prolapse (MVP) by real-time 3D echocardiography with color Doppler capability. METHODS: Twenty-seven patients with functional MR and 27 patients with MVP were examined. The horizontal PISA length in the commissure-commissure plane and each PISA radius in 3 anteroposterior planes (medial, central, and lateral) were measured by real-time 3D echocardiography with 3D software. The effective regurgitant orifice (ERO) area was calculated with the maximum PISA radius and compared to that by 2D quantitative Doppler method. RESULTS: En-face 3D color Doppler images showed an elongated and slightly curved PISA geometry along the leaflet coaptation in functional MR, whereas the geometry was rounder in MVP. The PISA horizontal length in functional MR was longer than that in MVP (2.3 +/- 0.4 vs 1.2 +/- 0.2 cm, P < .001). The PISA method with the maximum radius underestimated the ERO area by 2D quantitative Doppler method (by 24%) in functional MR, but not in MVP. CONCLUSIONS: The geometry of PISA in functional MR was elongated, distinctly different from the more focal pathology of MVP, leading to underestimation of the ERO area by PISA method.

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.

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.

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.

The effects of aging and physical activity on Doppler measures of diastolic function.

Healthy aging results in changes in Doppler measures of diastolic function. It is unclear whether these alterations are a specific manifestation of the aging process or reflect a cardiac adaptation to a more sedentary lifestyle. It was hypothesized that healthy, but sedentary, aging would result in slowing of diastolic filling and myocardial relaxation, whereas lifelong endurance training would prevent such changes. Doppler data were measured in young subjects and sedentary and fit seniors across a broad range of loading conditions. Thirteen sedentary healthy (70+/-4 years) and 12 fit Masters athlete (68+/-3 years) seniors were recruited. Twelve young healthy (32+/-9 years) subjects were used for comparison. Pulmonary capillary wedge pressure and Doppler variables were measured at the 6 loading conditions of baseline (twice), -15 and -30 mm Hg lower body negative pressure, and 2 levels of saline solution infusion. Doppler variables consisted of early and late mitral inflow velocity (E/A) ratio, isovolumetric relaxation time (IVRT), tissue Doppler velocities (TDI Emean), and propagation velocity of mitral inflow. Aging resulted in a decrease in E/A ratio (p<0.001), TDI Emean (p<0.001), and propagation velocity of mitral inflow (p<0.001) and an increase in IVRT (p=0.001). Lifelong endurance training did not completely prevent the changes in E/A ratio (p=0.212), IVRT (p=0.546), or propagation velocity of mitral inflow (p=1.00). Fit seniors were able to achieve E/A ratios of 1.0 during baseline and saline solution infusion. TDI Emean was higher in fit versus sedentary seniors at baseline (p=0.012) and during maximal lower body negative pressure (p=0.036), but not during saline solution infusion (p=0.493). In conclusion, age-associated abnormalities in Doppler measures of myocardial filling and relaxation are only partially minimized by lifelong endurance training and therefore may be more specific to the aging process than secondary to years of deconditioning.

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.

Effect of Gravitational Gradients on Cardiac Filling and Performance.

BACKGROUND: Gravity affects every aspect of cardiac performance. When gravitational gradients are at their greatest on Earth (i.e., during upright posture), orthostatic intolerance may ensue and is a common clinical problem that appears to be exacerbated by the adaptation to spaceflight. We sought to elucidate the alterations in cardiac performance during preload reduction with progressive upright tilt that are relevant both for space exploration and the upright posture, particularly the preload dependence of various parameters of cardiovascular performance. METHODS: This was a prospective observational study with tilt-induced hydrostatic stress. Echocardiographic images were recorded at four different tilt angles in 13 astronauts, to mimic varying degrees of gravitational stress: 0° (supine, simulating microgravity of space), 22° head-up tilt (0.38 G, simulating Martian gravity), 41° (0.66 G, simulating approximate G load of a planetary lander), and 80° (1 G, effectively full Earth gravity). These images were then analyzed offline to assess the effects of preload reduction on anatomical and functional parameters. RESULTS: Although three-dimensional end-diastolic, end-systolic, and stroke volumes were significantly reduced during tilting, ejection fractions showed no significant change. Mitral annular e' and a' velocities were reduced with increasing gravitational load (P < .001 and P = .001), although s' was not altered. Global longitudinal strain (GLS; from -19.8% ± 2.2% to -14.7% ± 1.5%) and global circumferential strain (GCS; from -29.2% ± 2.5% to -26.0% ± 1.8%) were reduced significantly with increasing gravitational stress (both P < .001), while the change in strain rates were less certain: GLSR (P = .049); GCSR (P = .55). End-systolic elastance was not consistently changed (P = .53), while markers of cardiac afterload rose significantly (effective arterial elastance, P < .001; systemic vascular resistance, P < .001). CONCLUSIONS: Preload modification with gravitational loading alters most hemodynamic and echocardiographic parameters including e' velocity, GLS, and GCS. However, end-systolic elastance and strain rate appear to be more load-independent measures to examine alterations in the cardiovascular function during postural and preload changes, including microgravity.

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.

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.

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.

Doppler-derived myocardial systolic strain rate is a strong index of left ventricular contractility.

BACKGROUND: Myocardial fiber strain is directly related to left ventricular (LV) contractility. Strain rate can be estimated as the spatial derivative of velocities (dV/ds) obtained by tissue Doppler echocardiography (TDE). The purposes of the study were (1) to determine whether TDE-derived strain rate may be used as a noninvasive, quantitative index of contractility and (2) to compare the relative accuracy of systolic strain rate against TDE velocities alone. METHODS AND RESULTS: TDE color M-mode images of the interventricular septum were recorded from the apical 4-chamber view in 7 closed-chest anesthetized mongrel dogs during 5 different inotropic stages. Simultaneous LV volume and pressure were obtained with a combined conductance-high-fidelity pressure catheter. Peak elastance (Emax) was determined as the slope of end-systolic pressure-volume relationships during caval occlusion and was used as the gold standard of LV contractility. Peak systolic TDE myocardial velocities (Sm) and peak (epsilon'(p)) and mean (epsilon'(m)) strain rates obtained at the basal septum were compared against Emax by linear regression. Emax as well as TDE systolic indices increased during inotropic stimulation with dobutamine and decreased with the infusion of esmolol. A stronger association was found between Emax and epsilon'(p) (r=0.94, P<0.01, y=0.29x+0.46) and epsilon'(m) (r=0.88, P<0.01) than for Sm (r=0.75, P<0.01). CONCLUSIONS: TDE-derived epsilon'(p) and epsilon'(m) are strong noninvasive indices of LV contractility. These indices appear to be more reliable than S(m), perhaps by eliminating translational artifact.

Importance of mitral valve repair associated with left ventricular reconstruction for patients with ischemic cardiomyopathy: a real-time three-dimensional echocardiographic study.

BACKGROUND: Left ventricular (LV) reconstruction surgery leads to early improvement in LV function in ischemic cardiomyopathy (ICM) patients. This study was designed to evaluate the impact of mitral valve (MV) repair associated with LV reconstruction on LV function 1-year after surgery in ICM patients assessed by real-time 3-dimensional echocardiography (3DE). METHODS AND RESULTS: Sixty ICM patients who underwent the combination surgery (LV reconstruction in 60, MV repair in 30, and revascularization in 52 patients) were studied. Real-time 3DE was performed and LV volumes were obtained at baseline, discharge, 6-month and >or=12-month follow-up. Reduction in end-diastolic volumes (EDV) by 29% and in end-systolic volumes by 38% were demonstrated immediately after surgery and remained at subsequent follow-up (P<0.0001). The LV ejection fraction significantly increased by about 10% at discharge and was maintained >or=12-month (P<0.0001). Although the LV volumes were significantly larger in patients with MV repair before surgery (EDV, 235+/-87 mL versus 193+/-67 mL, P<0.05), they were similar to LV volumes of the patients without MV repair at subsequent follow-ups. However, the EDV increased from 139+/-24 mL to 227+/-79 mL (P<0.01) in 7 patients with recurrent mitral regurgitation (MR). Improvement in New York Heart Association functional class occurred in 81% patients during late follow-up. CONCLUSIONS: Real-time 3DE demonstrates that LV reconstruction provides significant reduction in LV volumes and improvement in LV function which is sustained throughout the 1-year follow-up with 84% cardiac event free survival. If successful, MV repair may prevent LV redilation, while recurrent MR is associated with increased LV volumes.

Impact of left ventricular outflow tract area on systolic outflow velocity in hypertrophic cardiomyopathy: a real-time three-dimensional echocardiographic study.

OBJECTIVES: The aim of this study was to use real-time three-dimensional echocardiography (3DE) to investigate the quantitative relation between minimal left ventricular (LV) outflow tract area (A(LVOT)) and maximal LV outflow tract (LVOT) velocity in patients with hypertrophic obstructive cardiomyopathy (HCM). BACKGROUND: In patients with HCM, LVOT velocity should change inversely with minimal A(LVOT) unless LVOT obstruction reduces the pumping capacity of the ventricle. METHODS: A total of 25 patients with HCM with systolic anterior motion (SAM) of the mitral valve leaflets underwent real-time 3DE. The smallest A(LVOT) during systole was measured using anatomically oriented two-dimensional "C-planes" within the pyramidal 3DE volume. Maximal velocity across LVOT was evaluated by two-dimensional Doppler echocardiography (2DE). For comparison with 3DE A(LVOT), the SAM-septal distance was determined by 2DE. RESULTS: Real-time 3DE provided unique information about the dynamic SAM-septal relation during systole, with A(LVOT) ranging from 0.6 to 5.2 cm(2) (mean: 2.2 +/- 1.4 cm(2)). Maximal velocity (v) correlated inversely with A(LVOT) (v = 496 A(LVOT)(-0.80), r = -0.95, p < 0.001), but the exponent (-0.80) was significantly different from -1.0 (95% confidence interval: -0.67 to -0.92), indicating a significant impact of small A(LVOT) on the peak LVOT flow rate. By comparison, the best correlation between velocity and 2DE SAM-septal distance was significantly (p < 0.01) poorer at -0.83, indicating the superiority of 3DE for assessing A(LVOT). CONCLUSIONS: Three-dimensional echocardiography-measured A(LVOT) provides an assessment of HCM geometry that is superior to 2DE methods. These data indicate that the peak LVOT flow rate appears to be significantly decreased by reduced A(LVOT). Real-time 3DE is a potentially valuable clinical tool for assessing patients with HCM.

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.

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.