Determinants of exercise-induced pulmonary hypertension in rheumatic mitral stenosis: a study with exercise stress and speckle tracking echocardiography

Backgrounds

Exercise stress echocardiography is helpful in assessing hemodynamic consequence of mitral stenosis (MS) and in guiding treatment. Exercised-induced pulmonary hypertension (PH) is result of severity of MS, but myocardial function of left ventricle and clinical factors can also have effect.

Purpose

We aimed to evaluate the associated factors with the pulmonary artery systolic pressure (PASP) in exercise stress echocardiography through 2D, Doppler, and speckle tracking imaging in patients with rheumatic MS.

Methods

A total of 164 patients with rheumatic MS underwent a graded, symptom-limited, supine bicycle exercise with echocardiography. After exclusion of patients who had very severe MS (valve area <1.0 cm2), a history of surgery or recent percutaneous mitral valvotomy, combined significant aortic valve dysfunction, left ventricular (LV) ejection fraction <50%, we analyzed 113 patients (77.6% female; mean age, 56±9 years). Echocardiographic parameters at rest, each stage (25 watt increment every 3 minutes), and peak exercise were obtained. Exercised induced PH was defined as present if PASP >60 mmHg at peak exercise. LV global longitudinal strain (LV-GLS) and left atrial (LA) strain were analyzed by software. The subjects were divided into 4 groups according to mean transmitral pressure gradient (MG) (15 mmHg) and PASP (60 mmHg) at peak exercise (Group 1, MG <15 mmHg and PASP <60 mmHg, n=29; Group 2, MG <15 mmHg and PASP ≥60 mmHg, n=9; Group 3, MG ≥15 mmHg and PASP <60 mmHg, n=23; Group 4, MG ≥15 mmHg and PASP ≥6 0mmHg, n=52).

Results

The mean mitral valve area was 1.30±0.23 cm2. PASP increased from 30.0±8.0 mmHg at rest to 61.0±14.8 mmHg at peak exercise, along with increase MG. 61 (53.9%) subjects had PASP>60 mmHg at peak exercise. Compared to group 1, group 2 had higher incidence of diabetes mellitus (DM) and significantly elevated PASP at baseline and impaired LV-GLS. However, there was no statical difference in LA strain between the two groups. In subjects with MG above 15 mmHg (Group 3 and 4), a similar trend was observed in occurrence of exercise-induced PH. On logistic multivariate regression, exercised induced PH was independently associated with female (HR: 5.35, 95% CI: 1.51–24.95; p=0.032), DM (HR: 10.05, 95% CI, 1.35–74.45; p=0.024), MG at peak exercise (HR: 1.17, 95% CI, 1.02–1.34; p=0.002), PASP at rest (HR: 1.17, 95% CI, 1.05–1.30; p=0.002), and LV-GLS (HR: 1.45, 95% CI, 1.09–1.91; p=0.009), but not with LA strain. The predictive value for exercised induced PH was highest when adding LV-GLS to the clinical factor (age, sex, DM) and echocardiographic parameters (Figure 1).

Conclusions

Exercised induced PH is affected by not only hemodynamic consequence of MS, but also myocardial function of left ventricle and clinical factors. Therefore, when determining the optimal timing of intervention based on exercise-induced PH in rheumatic MS patients, LV-GLS should be evaluated comprehensively along with MS characteristics.

Funding Acknowledgement

Type of funding sources: Private hospital(s). Main funding source(s): Yonsei University College of Medicine

Assessment of aortic valve area on cardiac computed tomography and doppler echocardiography: differences and clinical significance in symptomatic bicuspid aortic stenosis

Backgrounds

This study aimed to investigate the differences and clinical significance of effective orifice area (EOA) on Doppler echocardiography and geometric orifice area (GOA) on cardiac computed tomography (CT) in bicuspid aortic stenosis (AS).

Methods

One-hundred sixty-three consecutive patients (age 64±10 years, 56.4% men) with symptomatic bicuspid AS who were referred for surgery and underwent both cardiac CT and echocardiography within 3 months were studied. For the aortic valve area, GOACT was measured by multiplanar CT planimetry, and EOAEcho was calculated by continuity equation with Doppler echocardiography. The associations of GOACT and EOAEcho with the patients' symptom scale, biomarkers, and left ventricular (LV) functional variables were comprehensively analyzed.

Results

There was a significant but modest correlation between EOAEcho and GOACT (r=0.604, p<0.001). Both EOAEcho and GOACT revealed significant correlations with mean pressure gradient and peak transaortic velocity and the coefficients were higher in EOAEcho than GOACT. EOAEcho of 1.05 cm2 and GOACT of 1.25 cm2 correspond to the hemodynamic cut-off values for diagnosing severe AS. EOAEcho was well correlated with patients' symptom scale and log NT-pro BNP, but GOACT was not. In addition, EOAEcho showed higher correlation coefficient with estimated LV filling pressure and LV global longitudinal strain than GOACT.

Conclusions

Both EOAEcho and GOACT can be used to evaluate the severity of bicuspid AS, however, the threshold for GOACT for diagnosing severe AS should be applied higher than that for EOAEcho. EOAEcho tends to be more correlated with the patients' symptom degree, biomarkers, and LV functional variables than GOACT.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): The Korean Cardiac Research Foundation

Identification of distinct subgroups in moderately severe rheumatic mitral stenosis using data-driven phenotyping of longitudinal hemodynamic progression

Background

Rheumatic mitral stenosis (MS) is a significant cause of valvular heart disease. Pulmonary artery systolic pressure (PASP) reflects the hemodynamic consequences of MS and is used to determine treatment strategies. However, PASP progression and expected outcomes in patients with moderately severe MS remain unclear.

Purpose

We aimed to examine the impact of progression rate of PASP in moderately severe MS.

Methods

A cohort of 866 consecutive patients with moderately severe rheumatic MS (1.0 cm2.

Results

Data-driven phenotyping identified two distinct trajectories based on PASP progression: a rapid progression group (N=38, 8.7%) and a slow progression group (N=398, 91.3%). Patients in the rapid progression group were older and had more comorbidities than patients in the slow progression group, including diabetes, and atrial fibrillation (all P<0.05). The initial mean diastolic pressure gradient and PASP were higher in the rapid progression group than in the slow progression group (6.2±2.4 mmHg vs. 5.1±2.0 mmHg, P=0.001, and 42.3±13.3 mmHg vs. 33.0±9.2 mmHg, P<0.001, respectively). During a mean follow-up of 7.0±3.0 years, the event-free survival rate was significantly lower in the rapid progression group than in the slow progression group (log-rank P<0.001). Rapid PASP progression was a significant risk factor for composite outcomes even after adjusting for comorbidities (hazard ratio: 3.08, 95% confidence interval (CI): 1.68–5.64, P<0.001). Multivariate regression analysis revealed that PASP>40 mmHg was independently associated with the probability of rapid progression group allocation (odds ratio: 4.95, 95% CI: 2.08–11.99, P<0.001).

Conclusions

Two groups with distinct patterns of PASP progression were identified. Rapid PASP progression was associated with a significantly higher risk of the composite outcomes. The main independent echocardiographic predictor for rapid progression group allocation was initial PASP>40 mmHg.

Funding Acknowledgement

Type of funding sources: Private hospital(s). Main funding source(s): This study was supported by a Severance Hospital Research fund for Clinical excellence (SHRC) (C-2020-0041) and a faculty research grant of Yonsei University College of Medicine (6-2020-0156).

Characteristics and clinical implications of premature summation of early and late diastolic filling in patients without tachycardia

Backgrounds

The summation of early (E) and late diastolic filling (A) on mitral inflow Doppler even in the absence of tachycardia is often found during assessments of left ventricular (LV) diastolic function. We evaluated the echocardiographic characteristics and clinical implications of premature E-A summation.

Methods

We identified 1,014 subjects who showed E-A summation and normal LV ejection fraction between January 2019 and June 2021 in two tertiary hospitals. Among these, 105 (10.4%) subjects showed premature E-A summation at heart rates less than 100 beats per minute (bpm). The conventional echocardiographic parameters and LV global longitudinal strain (GLS) were compared with 1:1 age, sex, and heart rate matched controls without E-A summation.

Results

The premature E-A summation group had a heart rate of 96.4±3.7 bpm. Only 4 (3.8%) subjects were classified as having LV diastolic dysfunction according to the current guidelines. That group showed prolonged isovolumic relaxation time (107.2±25.3 vs. 61.6±15.6 msec, p<0.001), increased Tei index (0.76±0.19 vs. 0.48±0.10, p<0.001), lower LVEF (63.8±7.0 vs. 67.3±5.6%, p<0.001) and lower absolute LV GLS (|LV GLS|) (17.0±4.2 vs. 19.7±3.3%, p<0.001) than controls. As the E-A summation occurred at lower heart rate, the |LV GLS| was also lower (p for trend=0.002).

Conclusions

The premature E-A summation at heart rates less than 100 bpm is associated with subclinical LV dysfunction. Time-based indices and LV GLS are helpful for evaluating this easily overlooked population.

Funding Acknowledgement

Type of funding sources: None.

Differential characteristics associated with progression of mitral and aortic regurgitation in patients undergoing kidney transplantation

Background

Heart valve regurgitation is common in patients with end-stage renal disease (ESRD). However, there are no data on the fate of mitral regurgitation (MR) and aortic regurgitation (AR) after kidney transplantation (KT). In this study, we sought to investigate regression or progression rates of MR and AR after KT in patients with ESRD. Moreover, we aimed to explore clinical and echocardiographic factors associated with the progression of MR and AR in patients undergoing KT.

Methods

Among 1,734 patients who underwent KT from 2005 to 2018 at a single tertiary hospital, 674 patients (407 men; mean 48±12 years) who underwent both pre- and post-KT echocardiography were analyzed comprehensively. Pre-KT echocardiography was performed within three months of KT, and post-KT echocardiography was done between 6 months and 24 months after KT. Severities of MR and AR were graded as no/trivial, mild, moderate, and severe according to the current guidelines. Regression was defined if the severity decreased by one or more grades, while progression was defined if the severity increased by one or more grades.

Results

Figure 1 shows the regression or progression of MR and AR after KT. 78 (11%) patients showed MR regression, but 41 (6%) experienced MR progression. 13 (2%) revealed AR regression, while 23 (4%) presented AR progression. In patients with MR progression, there were more cases of receiving a second KT, having mitral annular calcification, and showing lesser reduction of left atrial volume after KT. Patients with AR progression showed a longer hemodialysis duration, persistent hypertension after KT, and aortic root dilatation. Factors related to the progression of MR and AR showed statistically meaningful predictive values in a stepwise manner (Figure 2)

Conclusions

In patients undergoing KT, MR and AR may progress in patients with certain distinct characteristics. Different clinical and echocardiographic characteristics before KT, and reduction of hemodynamic loads after KT determine the progression of MR and AR. Further echocardiographic surveillances after KT are needed in patients with clinical and echocardiographic factors for progression of valve regurgitation.

Funding Acknowledgement

Type of funding sources: None.

Factors determining mitral valve dysfunction in patients who underwent surgical mitral valve replacement with bio-prosthetic valves

Background

There is increasing Interest in bio-prosthetic MVD as recent advances in transcatheter MV interventions, but there is limited data.

Objectives

The aim of this study was to identify the factors determining mitral valve (MV) dysfunction (MVD) in patients who underwent MV replacement with bio-prosthetic valves. Also, we sought to investigate clinical outcomes in patients with bio-prosthetic MVD.

Methods

A total of 233 patients underwent surgical bio-prosthetic MV replacement between June 1996 and May 2015. Finally, 226 patients (mean age 66.9±11.5 years, 74.3% of women) were analyzed, excluding patients who followed-up for less than 5 years and patients whose baseline or follow-up echocardiography could not be analyzed. Clinical, echocardiographic, and laboratory data were collected early after the surgery and during follow-up. MVD was defined as an increase in mean gradient ≥5 mmHg with leaflet motion limitation and/or newly developed MV regurgitation during follow-up. Clinical outcome was defined as a composite of cardiovascular death, redo MV surgery or intervention, and hospitalization for heart failure.

Results

During a median of 102.0 months (interquartile range 72.0 to 132.0 months), 65 patients (28.8%) revealed MVD. 8 (12.3%) patients revealed predominant MV obstruction, and 57 (87.7%) showed predominant MV regurgitation. Factors associated with bio-prosthetic MVD by multivariate regression analysis were young age at operation (hazard ratio 0.97, 95% CI 0.95–0.99, p=0.001), end-stage renal disease (hazard ratio 4.29, 95% CI 1.45–12.71, p=0.007), elevated mean diastolic pressure gradient>5.5 mmHg across the bio-prosthetic MV early after operation (hazard ratio 1.86, 95% CI 0.97–3.74, p=0.063) and anemia after operation (hazard ratio 0.84, 95% CI 0.74–0.95, p=0.007). However, the presence of hypertension, dyslipidemia, or porcine bio-prosthesis was not related to the bio-prosthetic MVD. Kaplan-Meier curves revealed significant differences in event-free survivals for the occurrence of bio-prosthetic MVD according to each factor (Figure 1). Patients with bio-prosthetic MVD showed significantly poor clinical outcomes compared with those without bio-prosthetic MVD (event-free survival 43.1% vs. 91.9%, log-rank p<0.001) during the follow-up.

Conclusions

Young age at operation, end-stage renal disease, elevated mean pressure gradient early after the operation, and anemia after operation were associated with bio-prosthetic MVD in patients who underwent bio-prosthetic MV replacement.

Funding Acknowledgement

Type of funding sources: None.

Evaluation of left ventricular filling pressure by echocardiography: incremental diagnostic information from left atrial strain

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): South-Eastern Norway Regional Health Authority

Background

Elevated left ventricular (LV) filling pressure is an important diagnostic feature of heart failure.

Objectives

To investigate determinants of left atrial (LA) reservoir and pump strain and if these parameters may serve as markers of LV filling pressure.

Methods

In a multicenter study of 322 patients with cardiovascular disease of different etiologies, LA strain by speckle tracking echocardiography was compared to conventional echocardiographic markers using invasive pressure as reference.

Results

Left ventricular filling pressure correlated well with LA reservoir and pump strain (r-values

‑0.52 and ‑0.57, respectively) (Figure). However, LV global longitudinal strain (GLS) was the strongest determinant of LA reservoir strain (r = 0.64), and correlated well with LA pump strain (r = 0.51).  For both LA strains, association with filling pressure was strongest in patients with reduced LV ejection fraction. In patients with normal GLS (≥18%), atrial strains provided no information regarding filling pressure (Figure). Reservoir strain <18% and pump strain <8% predicted elevated LV filling pressure better (p < 0.05) than the conventional indices LA volume, ratio of mitral early filling velocity/annular velocity and tricuspid regurgitation velocity. Accuracy to classify filling pressure as normal or elevated was 75% for both LA strains . When any one of the conventional indices were missing, and were replaced by LA strains, the combination of indices had accuracy 82% to correctly classify filling pressure.

Conclusions

Left atrial reservoir and pump strain may serve as clinical markers of LV filling pressure, but will be useful predominantly in patients with reduced systolic function.  Due to limited diagnostic accuracy, LA strain should be used in combination with other indices.

Abstract Figure

Association between mortality risk and the number, location, and sequence of subsequent fractures in the elderly

The mortality risk showed a positive correlation as the number of subsequent fractures increased. Hip fracture showed the greatest association with mortality risk, followed by vertebral fracture. For the combination of hip and vertebral fracture, a hip fracture after a vertebral fracture showed the highest mortality risk.

INTRODUCTION

It is unclear whether subsequent fractures or a certain location and sequence of subsequent fractures are associated with mortality risk in the elderly. We aimed to investigate the relationship between subsequent fractures and mortality risk.

METHODS

Using the Korean National Health Insurance Research Database, we analyzed the cohort data of 24,756 patients aged > 60 years who sustained fractures between 2002 and 2013. Cox regression was used to assess the mortality risk associated with the number, locations, and sequences of subsequent fractures.

RESULTS

Mortality hazard ratios (HRs) for women and men were shown to be associated with the number of subsequent fractures (one, 1.63 (95% confidence interval [CI], 1.48-1.80) and 1.42 (95% CI, 1.28-1.58); two, 1.75 (95% CI, 1.47-2.08) and 2.03 (95% CI, 1.69-2.43); three or more, 2.46(95% CI, 1.92-3.15) and 1.92 (95% CI, 1.34-2.74), respectively). For women, the mortality risk was high when hip (HR, 2.49; 95% CI, 1.80-3.44) or vertebral (HR, 1.40; 95% CI, 1.03-1.90) fracture occurred as a second fracture. Compared with a single hip fracture, there was a high mortality risk in the group with hip fracture after the first vertebral fracture (HR, 2.90; 95% CI, 1.86-4.54), followed by vertebral fracture after the first hip fracture (HR, 1.90; 95% CI, 1.12-3.22).

CONCLUSION

The mortality risk showed a positive correlation as the number of subsequent fractures increased. Hip fracture showed the greatest association with mortality risk, followed by vertebral fracture. For the combination of hip and vertebral fracture, a hip fracture after a vertebral fracture showed the highest mortality risk.

P1248Characteristics and clinical significance of right ventricular involvement in patients with hypertrophic cardiomyopathy

Background

A few studies have demonstrated bi-ventricular hypertrophy in hypertrophic cardiomyopathy (HCM). However, clinical significance of HCM with right ventricular (RV) involvement has not been fully established. Therefore, we aimed to investigate the structural characteristics and clinical significance of RV hypertrophy in patients with HCM.

Methods

In a single center, large HCM registry, 256 patients with HCM who underwent both cardiac magnetic resonance (CMR) and transthoracic echocardiography within 6 months were retrospectively analyzed. RV involvement was defined as increased RV wall thickness >7 mm on CMR in any segments of RV free wall and apex. Patients who had evidence of significant RV pressure overload (RV systolic pressure >50mmHg) or had undergone septal myectomy were excluded. Cardiovascular outcomes were defined as the composite of cardiovascular death and hospitalization for cardiovascular disease.

Results

Among 256 patients, 41 (16%) showed RV involvement. During follow-up period (median 1099 days), 32 cardiovascular outcomes (3 cardiovascular death and 29 cardiovascular hospitalization) were occurred. Patients with RV involvement showed a significantly higher left ventricular (LV) thickness (23.8±5.8 vs. 21.2±5.0 mm, p=0.004), more advanced diastolic dysfunction, and larger left atrial volume index (LAVI, 48.5±20.3 vs. 40.2±14.9 mm/m2, p=0.016) compared to those without RV involvement. In multivariate cox regression analysis, presence of RV involvement (HR: 4.21, 95% CI: 1.99–8.90, p<0.001) and LV ejection fraction <50% (HR: 4.29, 95% CI: 1.37–13.43, p=0.012) were independently associated with cardiovascular outcomes. The Kapan-Meier curve showed that there was a significant decrease in probability of cardiovascular outcomes-free survival in patients with RV involvement (p=0.007) after using 1:1 propensity score matching (n=82) to adjust for age, sex, LV ejection fraction, LV maximal wall thickness, LAVI, and RV systolic pressure than patients without RV involvement (Figure 1).

Figure 1

Conclusion

RV involvement in patients with HCM were not rare (16%). Patients with RV involvement showed more advanced LV structure and dysfunction, suggesting an indicator of severe HCM. RV involvement in HCM has clinical significance related to cardiovascular outcomes.

Probing a century old prediction one plasmonic particle at a time

In 1908, Gustav Mie solved Maxwell's equations to account for the absorption and scattering of spherical plasmonic particles. Since then much attention has been devoted to the size dependent optical properties of metallic nanoparticles. However, ensemble measurements of colloidal solutions generally only yield the total extinction cross sections of the nanoparticles. Here, we show how Mie's prediction on the size dependence of the surface absorption and scattering can be probed separately for the same gold nanoparticle by using two single particle spectroscopy techniques, (1) dark-field scattering and (2) photothermal imaging, which selectively only measure scattering and absorption, respectively. Combining the optical measurements with correlated scanning electron microscopy furthermore allowed us to measure the size of the spherical gold nanoparticles, which ranged from 43 to 274 nm in diameter. We found that even though the trend predicted by Mie theory is followed well by the experimental data over a large range of nanoparticle diameters, for small size variations changes in scattering and absorption intensities are dominated by factors other than those considered by Mie theory. In particular, spectral shifts of the plasmon resonance due to deviations from a spherical particle shape alone cannot explain the observed variation in absorption and scattering intensities.

Left ventricular diastolic functional reserve during exercise in patients with impaired myocardial relaxation at rest

BACKGROUND

Patients with similar grade diastolic dysfunction at rest may have a spectrum of alterations in diastolic function during exercise.

OBJECTIVE

To evaluate (a) whether exercise could unmask further diastolic abnormalities not evident during rest; (b) whether diastolic functional reserve during exercise is associated with exercise capacity.

METHODS

141 subjects (77 male, mean (SD) age 62 (9)) with abnormal left ventricular (LV) relaxation (mitral E/A <0.75) and/or deceleration time >240 ms, underwent graded supine bicycle exercise with simultaneous respiratory gas analysis and two-dimensional and Doppler echocardiographic study. Mitral inflow and annular velocities were measured at rest and during exercise. The LV diastolic function reserve index (DFRI) was calculated.

RESULTS

Patients were classified into two groups: group 1 (n = 64), DFRI <13.5; group 2 (n = 77), DFRI >or=13.5. The ratio of E/E' to stroke volume was used as an index of ventricular elastance (Ed). No significant differences between the groups in mitral inflow and annular velocities at rest were found. Mean (SD) Ed was not significantly different at rest between the groups (0.19 (0.07) vs 0.18 (0.06), p = 0.29). Ed was significantly higher during exercise in group 1 than in group 2 (25 W, 0.21 (0.09) vs 0.14 (0.04), p<0.001; 50 W, 0.22 (0.10) vs 0.15 (0.04), p<0.001). Group 1 subjects had a shorter exercise duration (8.2 (2.7) vs 9.4 (3.7) min, p = 0.04) and lower peak oxygen consumption (17.5 (4.5) vs 20.2 (5.4) ml/kg/min, p = 0.005).

CONCLUSIONS

Despite similar mitral flow and annular velocities at rest, different responses to exercise were seen in patients with abnormal LV relaxation at rest. Lower LV diastolic functional reserve was associated with higher ventricular elastance during exercise, and reduced exercise capacity.

Association of aortic plaque with intracranial atherosclerosis in patients with stroke

OBJECTIVE

To determine whether there is a relationship between aortic plaques and intracranial (IC) atherosclerosis.

METHODS

We reviewed 922 patients with stroke who had both transesophageal echocardiography and cerebral angiography. The plaques of these patients were classified as either complex aortic plaques (CAP), which protruded > or =4 mm or were present as mobile lesions in the proximal aorta, or simple aortic plaques (SAP), which were <4 mm or present in the descending aorta. Cerebral artery atherosclerosis was classified as either an IC or extracranial (EC) atherosclerosis.

RESULTS

Among the 922 patients, we found aortic plaques in 237 patients (26%). There were 111 (47%) patients of SAP, 74 (31%) patients with CAP, and 52 (22%) patients that had both SAP and CAP. Angiography showed IC or EC atherosclerosis in 511 patients (55%). The presence of aortic plaques was significantly associated with IC or EC atherosclerosis. The significance appeared to be due to the strong association between the presence of SAP and IC atherosclerosis (51% SAP vs 35% no plaques; odds ratio = 1.94, 95% CI: 1.17 to 3.21). In the multiple logistic regression analysis, SAP were independent predictors of IC atherosclerosis

CONCLUSIONS

The presence of simple aortic plaques may be a marker of advanced vascular disease. Detection of simple aortic plaques during transesophageal echocardiography may have clinical implications because patients with these plaques frequently had concomitant intracranial atherosclerosis, a risk factor for stroke.

Biomechanical evaluation of diagonal fixation in pedicle screw instrumentation

STUDY DESIGN

Flexibility tests and finite element analyses were performed for the biomechanical evaluation of diagonal transfixation in pedicle screw instrumentation.

OBJECTIVE

To assess the biomechanical advantages of diagonal transfixation compared with conventional horizontal transfixation.

SUMMARY AND BACKGROUND DATA

A few pedicle screw instrumentation systems allow the use of cross-links in the diagonal direction. Such a diagonal transfixation is anticipated to improve the surgical construct stability, but its biomechanical qualities have not been completely evaluated.

METHODS

Flexibility tests were performed on 10 calf lumbar spines (L2-L5). Specimens were subjected to pure moments up to 8.2 Nm in flexion, extension, lateral bending, and extension while the resulting movements of L3 and L4 were measured by a three-dimensional motion analysis system. The tested cases included (1) intact, (2) pedicle screw fixation without transfixation after total removal of the L3-L4 disc, (3) pedicle screw fixation with diagonal transfixation, and (4) pedicle screw fixation with horizontal transfixation. Three-dimensional finite element models of the tested surgical constructs were also developed by use of three-dimensional beam elements to investigate the effect of diagonal transfixation and horizontal transfixation on the construct stability and the corresponding stress changes in the screws.

RESULTS

When compared with no transfixation, horizontal transfixation significantly improved the lateral bending and axial rotation stability by 15.7% and 13.9%, respectively, but there was no improvement of stability in flexion and extension. By contrast, diagonal transfixation significantly improved the flexion and extension stability by 12% and 10.7%, respectively, but not the lateral bending and axial rotation stability in comparison with no transfixation. Comparison between horizontal transfixation and diagonal transfixation showed that the stabilizing effect of diagonal transfixation was greater in flexion and extension (13% and 11%, P < 0.01) than that of horizontal transfixation but smaller in lateral bending (11%, P < 0.05) and axial rotation (6.6%, P > 0.1). Finite element model predictions of the motion changes were similar to the changes observed in flexibility tests. In horizontal transfixation, the load changes, compared with no transfixion, were a 0.02% increase in flexion-extension, a 27.5% increase in lateral bending, and a 58% decrease in axial rotation, and the magnitudes of the moments applied on both the right and left pedicle screws were identical. However, when diagonal transfixation was achieved by connecting the left superior screw and the right inferior screw, the loads in the left screw were increased by 11.5% in flexion-extension, 43.6% in lateral bending, and 7.9% in axial rotation, whereas the loads in the right screw were decreased by 10.9% in flexion-extension, increased by 0.06% in lateral bending, and decreased by 18.1% in axial rotation.

CONCLUSIONS

The results of this study showed that diagonal transfixation provides more rigid fixation in flexion and extension but less in lateral bending and axial rotation in comparison with horizontal transfixation. Furthermore, greater stresses in the pedicle screws were predicted in the diagonal transfixation model. These limitations of diagonal transfixation should be considered carefully for clinical application.

Assessment of left atrial appendage filling pattern by using intravenous administration of microbubbles: comparison between mitral stenosis and mitral regurgitation

Mitral stenosis (MS) and mitral regurgitation (MR) are the most frequent conditions that cause a dilation and dysfunction of the left atrial appendage (LAA). Despite similarly dilated LAA in patients with MS and MR, the incidence of LAA thrombi and the risk of thromboembolism is different between these patients. The purpose of this study was to characterize the filling pattern of LAA by using intravenous administration of perfluorocarbon-exposed dextrose albumin (PESDA) during transesophageal echocardiographic examination in patients with MS and MR. Twenty-four patients with moderate to severe MS, 12 patients with severe MR, and a control group including 30 patients with conditions other than mitral valve disease underwent transesophageal echocardiographic examination with an intravenous bolus injection of PESDA. LAA emptying and filling velocities and maximal and minimal areas of LAA and LAA ejection fraction were measured. Digital gray-scale intensity (GSI) of the left atrial (LA) and LAA cavity after PESDA injection was measured by off-line analysis. Compared with control patients, patients with MS or MR had larger maximal and minimal areas of LAA and reduced LAA ejection fraction. LAA peak emptying flow velocity was significantly lower in patients with MS compared with those of MR or control patients. LAA peak filling velocity was significantly lower in patients with MS compared with that of control patients. However, there was no significant difference of LAA peak filling velocity between the patients with MS and MR. There was no significant difference of GSI ratio of LAA and LA between patients with MR and control patients; however, GSI ratio of LAA and LA was significantly lower in patients with MS compared with that of MR. The incidence of LAA spontaneous echo contrast and LAA thrombi in patients with MS was significantly higher than that of the patients with MR and control subjects (P <.005). Despite similarly dilated LAA area and depressed contractile function of LAA in patients with MS and MR compared with control patients, profoundly impaired LAA filling with resultant flow stasis was demonstrated by contrast echocardiography in patients with MS. These findings may explain the higher incidence of LAA spontaneous echo contrast and thrombus in patients with MS.

Annulus paradoxus: transmitral flow velocity to mitral annular velocity ratio is inversely proportional to pulmonary capillary wedge pressure in patients with constrictive pericarditis

BACKGROUND

The early diastolic velocity of the mitral annulus (E') is reduced in patients with diastolic dysfunction and increased filling pressures. Because transmitral inflow early velocity (E) increases progressively with higher filling pressures, E/E' has been shown to have a strong positive relationship with pulmonary capillary wedge pressure (PCWP) and left ventricular end-diastolic pressure. However, previous studies have primarily involved patients without a pericardial abnormality. In constrictive pericarditis (CP), E' is not reduced, despite increased filling pressures. This study evaluated the relationship between E/E' and PCWP in patients with CP.

METHODS AND RESULTS

We studied 10 patients (8 men; mean age, 64+/-7 years) with surgically confirmed CP. Doppler echocardiography was performed to measure early and late diastolic transmitral flow velocities. Tissue Doppler echocardiography was performed to measure E'. PCWP was measured with right heart catheterization. All patients were in sinus rhythm. Mean E and E' were 91+/-15 cm/s and 11+/-4 cm/s, respectively. Mean PCWP was 25+/-6 mm Hg. E' was positively correlated with PCWP (r=0.69, P=0.027). There was a significant inverse correlation between E/E' and PCWP (r=-0.74, P=0.014). Despite high left ventricular filling pressures, E/E' (mean, 9+/-4) was <15 in all but 1 patient.

CONCLUSIONS

Paradoxical to the positive correlation between E/E' and PCWP in patients with myocardial disease, an inverse relationship was found in patients with CP.

Flail aortic valve and acute aortic regurgitation due to spontaneous localized intimal tear of ascending aorta

This report describes the transesophageal echocardiographic findings of acute severe aortic regurgitation resulting from localized transverse intimal tear of ascending thoracic aorta which could not be suspected as a cause of flail aortic valve preoperatively. In patients with chest pain and acute aortic regurgitation associated with flail aortic valve, localized intimal tear of aorta should be considered as a possible cause of flail aortic valve.

Left atrial appendage stenosis

We describe an unusual case with an anatomic narrowing at the opening of the left atrial appendage demonstrated by two-dimensional color Doppler and continuous-wave Doppler transesophageal echocardiography.

Enhanced detection of right-to-left shunt through patent foramen ovale by transthoracic contrast echocardiography using harmonic imaging

When the results of transesophageal echocardiography was regarded as the gold standard for detecting a patent foramen ovale (PFO) in 136 consecutive patients referred for evaluation of cardiac source of embolism, transthoracic harmonic imaging using saline contrast was superior to fundamental imaging in accuracy for detecting a PFO (sensitivity, 22.5%; specificity [p < 0.05] and sensitivity, 100%; specificity 100%, respectively.)

Effects of left atrial compliance on left atrial pressure in pure mitral stenosis

In mitral stenosis (MS), left atrial (LA) pressure is commonly elevated because of increased LA afterload. There is a wide spectrum of LA pressure in patients with MS, however, despite a similar mitral valve orifice area. LA compliance is an important determinant of both cardiovascular performance and pathological physiology. Few data are available, however, regarding the effects of LA compliance on LA pressure. We hypothesized that LA pressure may be higher in patients with decreased LA compliance. We analyzed the right heart and transseptal catheterization data in 47 patients (41 female, mean age 40 +/- 10 years) with pure MS and sinus rhythm. The magnitude of LA a and v waves was measured from transseptal catheterization. Fick's method was used to determine cardiac output. LA compliance was calculated by dividing the systolic rise in LA pressure (DeltaP(LA) = P(LA(v)) - P(LA(x))) into the stroke volume. LA size, mitral valve area (MVA), mean diastolic pressure gradient (MG), left ventricular (LV) end-diastolic and end-systolic dimensions were obtained by using two-dimensional and Doppler echocardiography. Multiple regression analysis was performed to identify independent factors determining LA pressure. The mean MVA was 0.95 +/- 0.22 cm(2). MG and LA dimension were 11.2 +/- 5.2 mm Hg and 50.6 +/- 5.2 mm, respectively. The mean LA pressure and cardiac output obtained by cardiac catheterization were 23.4 +/- 8.4 mm Hg and 4.3 +/- 1.5 L/min, respectively. The calculated LA compliance was 4.9 +/- 2.8 cm(3)/mm Hg. Univariate analysis showed that factors associated with increased LA pressure were smaller MVA (r = -0.33, P < 0.05), higher MG (r = 0.69, P < 0.01) and lower LA compliance (r = -0.55, P < 0.01); among them, MG (beta coefficient 0.59, SE 0.19, P < 0.01) and LA compliance (beta coefficient -0.26, standard error 0.34, P < 0.05) were the strongest predictors of LA pressure. In conclusion, LA compliance, along with MG that reflects the severity of MS, is an important contributing factor determining LA pressure in patients with pure MS and sinus rhythm.

Assessment of elastic properties of the descending thoracic aorta by transesophageal echocardiography with acoustic quantification in patients with a stroke

Previous studies have described the use of transesophageal echocardiography (TEE) with acoustic quantification (AQ) in assessing aortic elastic properties. We hypothesized that patients with a prior history of stroke (ST) may have a higher risk of atherosclerotic change in great vessels compared to nonstroke subjects (NST) and thus have decreased elastic properties. We assessed the elastic properties of the descending thoracic aorta (DTA) by TEE in ST patients and compared them with data in NST patients. Subjects included 31 with ST without any evidence of emboli originating from the heart (age 51 +/- 10 years, M:F = 20:11) and 25 age-matched NST (M:F = 8:17). Patients with significant valvular heart disease including aortic and mitral regurgitation, left ventricular dysfunction (ejection fraction < 55%), and congenital heart disease were excluded. Compliance (C), distensibility (D), and stiffness index (SI) were measured using AQ and M-mode measurement at a level of the left atrium. We scored atherosclerotic risk factors (ARF) such as a history of diabetes, hypertension, smoking, hypercholesterolemia, and the presence of atheroma of DTA. There was no evidence of atheroma of DTA in NST. There were no significant differences in heart rate and systolic and diastolic blood pressure between ST and NST patients. Fractional area change (FAC) of DTA was significantly lower in ST than in NST patients (3.2 +/- 1.6 vs 5.4 +/- 2.5%, P = 0.000). ST patients had significantly lower C (1.2 +/- 0.4 vs 1.5 +/- 0.7 x 10(-3) cm2 mmHg(-1), P = 0.039), lower D (0.8 +/- 0.3 vs 1.5 +/- 0.8 x 10(-3) mmHg(-1), P = 0.000), and higher SI (10.3 +/- 8.8 vs 5.3 +/- 2.9, P = 0.006) than NST patients. ST patients without atheroma of DTA (n = 21) also had significantly lower C (1.1 +/- 0.4 vs 1.5 +/- 0.7 x 10(-3) cm2 mmHg(-1), P = 0.038) and lower D (3.5 +/- 1.4 vs 4.8 +/- 2.4 x 10(-3) mmHg(-1), P = 0.021) than NST patients. There was a significant positive correlation between SI and the score of ARF (r = 0.51, P = 0.000). The regional elastic properties of DTA measured by TEE with AQ and M-mode method were abnormal in ST. Therefore, TEE with AQ technique may have a possible clinical application for the detection of early atherosclerotic changes such as alteration of elastic properties in morphological normal DTA.

Sexual dysfunction in men with paraparesis in lumbar burst fractures

STUDY DESIGN

A retrospective follow-up study.

OBJECTIVES

To review and analyze the sexual function of patients who have sustained lumbar fractures with incomplete paraparesis.

SUMMARY OF BACKGROUND DATA

As a result of advances in surgical techniques, most patients with lumbar fractures have significant recovery of neurologic status. Because motor functions are important to patients, most of the studies have concentrated their analyses on motor recovery. Many patients who have almost completely recovered motor function, however, may have sexual dysfunction, especially men.

METHODS

Forty-three patients with lumbar fractures that resulted in incomplete paraparesis were analyzed. American Spinal Injury Association motor index points were determined for each patient before and after surgery and used for comparison between American Spinal Injury Association motor index and international index of erectile function score. Eleven male patients who reported sexual dysfunction were evaluated by using Rigiscan.

RESULTS

During the follow-up period, 42 patients showed neurologic recovery. Average improvement of American Spinal Injury Association motor score was 13. 1 and average international index of erectile function score was 45. Average improvement of American Spinal Injury Association motor score for patients who had not reported sexual dysfunction was 12.5, and average international index of erectile function score was 52. For 11 patients in the sexual dysfunction group, preoperative motor score was 28.0, and average improvement of score was 14.9. Nocturnal penile tumescence monitoring results were abnormal in four cases. Averaged international index of erectile function score was 15. There was a statistically significant difference between the sexually healthy and dysfunctional groups in international index of erectile function score (P < 0.05), whereas no difference was noted in American Spinal Injury Association motor score.

CONCLUSIONS

Neurologic recovery after lumbar fractures was improved. Regardless of neurologic recovery, most patients reported some disability, usually caused by pain and occasionally sexual dysfunction. Impairment of sexual function was present in four patients (9.3%). Although these patients may preserve psychiatric erection potential, they usually experienced sexual problems.

Enhanced detection of left atrial spontaneous echo contrast by transthoracic harmonic imaging in mitral stenosis

BACKGROUND

Spontaneous echo contrast (SEC) of the left atrium is associated with increased risk of thromboembolism in patients with mitral stenosis (MS). The determination of the presence and severity of left atrial (LA) SEC is of prognostic importance in these patients. Harmonic imaging (HI), a novel echocardiographic technique that differs from conventional fundamental imaging (FI) in that it involves transmitting ultrasound at one frequency and receiving at twice the transmitted frequency, produces better endocardial border definition and myocardial opacification. However, there are no data about its value for the detection of LA SEC. The purpose of this study was to investigate the utility of transthoracic noncontrast tissue HI in the detection of LA SEC in patients with MS.

METHODS

Seventy-four consecutive patients with MS (49 women, mean age 51 years) underwent standard transthoracic echocardiography (TTE) in both HI and FI modes and transesophageal echocardiography (TEE) to determine the presence and severity of LA SEC. Left atrial SEC was graded by TEE as either mild (only seen at high gain) or severe (visible in the entire left atrium at normal gain control of the equipment). The control group comprised 30 patients randomly selected from patients who did not have LA SEC at the TEE examination.

RESULTS

Atrial fibrillation was found in 46 patients (62.2%). The mean mitral valve area and mean mitral gradient were 1.0+/-0.3 cm(2) and 8.2+/-4.1 mm Hg, respectively. Nine patients (12.2%) had episodes of systemic embolism; 8 had stroke, and 1 had peripheral embolism. Left atrial thrombus was found in 11 patients (14.9%) by TEE. Left atrial SEC was present in all but one patient by TEE (mild in 35 patients, severe in 38). Fundamental imaging with TTE, however, revealed LA SEC in only 5 (6.8%) of the 73 patients. In contrast, with HI, LA SEC could be detected in 63 (86.3%) patients. In the detection of severe LA SEC, the sensitivities of FI and HI were 13.2% (5/38) and 100% (38/38), respectively. Left atrial SEC was not observed in control subjects by either FI or HI.

CONCLUSIONS

Transthoracic HI significantly enhances the detection of LA SEC in patients with MS.

Unilateral versus bilateral pedicle screw fixation in lumbar spinal fusion

STUDY DESIGN

A prospective study of 87 patients who underwent unilateral or bilateral pedicle screw fixation.

OBJECTIVES

To determine whether unilateral pedicle screw fixation is comparable with bilateral fixation in one- or two-segment lumbar spinal fusion.

SUMMARY OF BACKGROUND DATA

Clinical results for unilateral variable screw placement instrumentation in isolated L4-L5 fusion have been reported to be as good as those for bilateral instrumentation. However, unilateral instrumentation may not be recommended for multilevel fusion.

METHODS

Eighty-seven patients were assigned to either unilateral (n = 47) or bilateral (n = 40) pedicle screw instrumentation groups. Two kinds of pedicle screw system (Moss Miami, DePuy, Warsaw, IN, and Steffee VSP, AcroMed, Cleveland, OH) were used. Operating time, blood loss, duration of hospital stay, clinical outcomes, fusion rates, complication rates, and medical expenses were studied and tested with independent sample t test and chi2 test.

RESULTS

There were no significant differences between the two groups in blood loss, clinically satisfactory results, fusion rate, and complication rate. There were significant differences in duration of operating time, duration of hospital stay, and medical expenses. The number of fusion segments or kinds of instrumentation did not affect the fusion rate or clinical outcomes.

CONCLUSIONS

Unilateral pedicle screw fixation was as effective as bilateral pedicle screw fixation in lumbar spinal fusion independent of the number of fusion segments (one or two segments) or pedicle screw systems. Based on the results of this study, unilateral fixation could be used in two-segment lumbar spinal fusion.

Evaluation of cardiac adrenergic neuronal damage in rats with doxorubicin-induced cardiomyopathy using iodine-131 MIBG autoradiography and PGP 9.5 immunohistochemistry

Doxorubicin is one of the most useful anticancer agents, but its repeated administration can induce irreversible cardiomyopathy as a major complication. The purpose of this study was to investigate doxorubicin toxicity on cardiac sympathetic neurons using iodine-131-metaiodobenzylguanidine (MIBG) and protein gene product (PGP) 9.5 immunohistochemistry, which is a marker of cardiac innervation. Wistar rats were treated with doxorubicin (2 mg/kg, i.v.) once a week for 4 (n=5), 6 (n=6) or 8 (n=7) weeks consecutively. Left ventricular ejection fraction (LVEF), calculated by M-mode echocardiography, was used as an indicator of cardiac function. Plasma noradrenaline (NA) concentration was measured by high-performance liquid chromatography (HPLC). 131I-MIBG uptake of the left ventricular wall (24 ROIs) was measured by autoradiography. 131I-MIBG uptake pattern was compared with histopathological results, the neuronal population on PGP 9.5 immunohistochemistry and the degree of myocyte damage assessed using a visual scoring system on haematoxylin and eosin and Masson's trichrome staining. LVEF was significantly decreased in the 8-week group (P<0.05). The serum NA level also showed no statistical difference until 4 weeks and was significantly increased in the 8-week group (P<0.05). MIBG uptake was decreased in the 6- and 8-week groups (P<0.05), and was closely correlated with the reduction in the number of nerve fibres on PGP 9.5 stain. Myocyte damage was seen only in the 8-week group. Neuronal population and the 131I-MIBG uptake ratio of subepicardium to subendocardium were significantly increased (P<0.05) in the 8-week group as compared with the control group. It may be concluded that radioiodinated MIBG is a reliable marker for the detection of cardiac adrenergic neuronal damage in doxorubicin-induced cardiomyopathy; it detects such damage earlier than do other clinical parameters and in this study showed a good correlation with the reduction in the neuronal population on PGP 9.5 stain. The subendocardial layer appeared to be more vulnerable to doxorubicin than the subepicardium.

Is the left atrial v. wave the determinant of peak pulmonary artery pressure in patients with pure mitral stenosis?

A large left atrial (LA) v. wave can be observed in patients with pure mitral stenosis (MS) because of decreased LA compliance. Few data are available regarding the relation between the magnitude of the LA v wave and pulmonary artery pressure in MS. We hypothesized that pulmonary artery pressure may be higher in patients with decreased LA compliance and thus a large v. wave. We analyzed the right-sided cardiac and transseptal catheterization data in 113 patients (16 men and 97 women, mean age 39 years) with pure rheumatic MS in sinus rhythm. Peak systolic, diastolic, and mean pulmonary artery pressures were measured with right-sided cardiac catheterization. The magnitude of LA a and v. waves were measured through transseptal catheterization. Two-dimensional and Doppler echocardiography were also performed to measure LA size, mitral valve area, mean mitral gradient, and valvular regurgitation. Multiple regression analysis was performed to identify the most important factor in the determination of pulmonary artery pressure. A large v wave, defined if peak v wave height exceeded the mean LA pressure by > or =10 mm Hg, was observed in 43 of 113 patients (38%). Increased pulmonary artery systolic pressure (> or =50 mm Hg) was observed in 38 patients (34%). Univariate analysis showed that the factors associated with increased pulmonary artery systolic pressure were smaller mitral valve area, higher mean mitral gradient, higher mean LA pressure, and higher LA v. wave; among them, LA v wave (p <0. 001) and mean mitral gradient (p<0.001) were significant independent factors for pulmonary artery systolic pressure in multivariate analysis. In conclusion, in patients with pure MS and sinus rhythm, the magnitude of the LA v. wave is strongly associated with pulmonary artery pressure. This finding may suggest that LA compliance is a major contributing factor determining pulmonary artery pressure in pure MS.

Assessment of myocardial metaiodobenzylguanidine uptake and its relation to left ventricular systolic and diastolic functional parameters in dilated cardiomyopathy

The purpose of this study was to assess the relation between myocardial metaiodobenzylguanidine (MIBG) uptake and left ventricular systolic and diastolic functional parameters, both of which are known as predictors of prognosis in patients with dilated cardiomyopathy. Echocardiography and iodine-123-MIBG myocardial scintigraphy were performed in 35 patients of dilated cardiomyopathy with normal sinus rhythm. Mean myocardial MIBG uptake in the patient group at early and delayed images were significantly lower than those in normal control subjects (10.6 +/- 1.1, 9.8 +/- 1.2 vs 12.4 +/- 1.0, 12.1 +/- 1.0, p < 0.01). There were, however, no significant differences of mean MIBG uptake in the lung and mediastinum between the two groups (p > 0.05). There were no significant correlations between myocardial MIBG uptake, expressed as the ratio of heart/mediastinum MIBG activity at delayed image, and left ventricular systolic and diastolic functional parameters [left ventricular ejection fraction, left ventricular end-diastolic dimension, peak velocity of early diastolic filling (E velocity), deceleration time of E wave, cardiac output, left ventricular end-diastolic pressure]. In conclusion, the myocardial uptake of MIBG is decreased in patients with dilated cardiomyopathy assessed by iodine-123-MIBG myocardial scintigraphy. There were, however, no significant correlations between myocardial MIBG uptake and left ventricular systolic and diastolic functional parameters derived from echocardiography.

Echocardiographic and morphologic characteristics of left atrial myxoma and their relation to systemic embolism

We examined the relation between the echocardiographic morphology of cardiac myxoma and systemic embolism in 25 patients. Two distinct types of myxoma could be identified by echocardiography: round type characterized by solid and round shape with nonmobile surface (n = 13, 52%), and polypoid type characterized by soft and irregular shape with mobile surface (n = 12, 48%); multiple regression analysis revealed the polypoid type of tumor was the only independent predictor of systemic embolism (p = 0.0029).

Breakup of a Multiple Emulsion Drop in a Uniform Electric Field

The steady deformation and breakup of emulsion drops in a uniform electric field are considered experimentally. Due to the low volume fraction of inner drops, the emulsions can be effectively assumed as Newtonian fluids with spatial nonuniformity. The measurements of the electrical properties show that the oil-in-water (o/w) emulsion drop behaves like a conducting drop. On the other hand, the water-in-oil (w/o) emulsion drops can be regarded as inhomogeneous leaky dielectric drops. It is found that the viscosity ratio is not an important parameter within the small deformation limit and breakup mode of the o/w emulsion drops. In the case of w/o emulsion drops, however, the breakup mode depends on the viscosity ratio. Inherent nonuniformity of the emulsion drops makes drop more deformable and unstable. The tip-streaming is the dominant breakup mode of o/w emulsion drops when the nonuniformity of drop phase is appreciable. Copyright 1999 Academic Press.

Noninvasive evaluation of coronary artery bypass graft patency using three-dimensional angiography obtained with contrast-enhanced electron beam CT

OBJECTIVE

The purpose of this study was to determine the accuracy of three-dimensional coronary angiography obtained with electron beam CT in the assessment of the patency of coronary artery bypass grafts.

SUBJECTS AND METHODS

Twenty-five patients who had undergone coronary artery bypass graft surgery were included. All patients underwent electron beam CT and conventional coronary angiography for the evaluation of the status of their bypass grafts. Three-dimensional reconstructions of the heart and bypass grafts were compared with selective angiographic images of the bypass grafts.

RESULTS

Fifty-seven saphenous vein grafts and 22 left internal mammary artery grafts were evaluated for occlusion or patency. Sensitivity and specificity of electron beam CT in revealing left internal mammary artery patency were 80% and 82.4%, respectively. Sensitivity and specificity of electron beam CT in revealing saphenous vein graft patency were 91.7% and 91.1%, respectively. Sensitivity and specificity of electron beam CT for evaluating saphenous vein grafts according to coronary area were as follows: saphenous vein grafts to left anterior descending artery, 100% and 100%, respectively; to diagonal branch, 100% and 100%; to left circumflex artery, 100% and 88.9%; and to right coronary artery, 75% and 85.7%.

CONCLUSION

Three-dimensional coronary angiography obtained with electron beam CT is a promising, useful, and relatively accurate diagnostic imaging technique for the evaluation of graft patency in patients who have undergone coronary artery bypass graft surgery.