Clinical Situations Associated with Inappropriately Large Regurgitant Volumes in the Assessment of Mitral Regurgitation Severity Using the Proximal Flow Convergence Method in Patients with Chordae Rupture.

BACKGROUND: Regurgitant volume (RVol) calculated using the proximal flow convergence method (proximal isovelocity surface area [PISA]) has been accepted as a key quantitative parameter for the diagnosis of and clinical decision-making with regard to severe mitral regurgitation (MR). However, a recent prospective study showed a significant overestimation of RVol by the echocardiographic PISA method compared with the MR volume measured using magnetic resonance imaging. We aimed to evaluate the frequency of overestimation of RVol by the PISA method and the clinical conditions that require a different quantitative method to correct the overestimation. METHODS: We retrospectively enrolled 166 consecutive patients with degenerative MR and chordae rupture, in whom RVol was measured using both the PISA and two-dimensional Doppler volumetric methods. The volumetric method was used to measure total stroke volume using the two-dimensional Simpson biplane method, and forward stroke volume was measured using pulsed Doppler tracing at the left ventricular (LV) outflow tract. RVol by the volumetric method was calculated using total stroke volume - forward stroke volume. Severe MR was defined as an RVol >60 mL. RESULTS: All patients had severe MR based on RVol by the PISA method, but 68 (41.1%) showed RVol by the volumetric method values of <60 mL, resulting in discordant results. The patients with discordant results were characterized by a higher prevalence of female sex, lower body surface area, smaller LV diastolic and systolic dimensions and volumes, smaller left atrial volume, smaller PISA angle, and lower frequency of flail leaflets (39.7% vs 62.2%, P = .004). Multivariate analysis revealed that LV end-diastolic volume (LVEDV) and PISA angle were independent factors, with the best cutoff LVEDV and PISA angle being 173 mL and 103°, respectively. During follow-up (median, 3.4 years; interquartile range, 2.0-4.8 years), mitral valve repair and replacement were performed in 103 and six patients, respectively. The 2-year mitral valve surgery-free survival rate was higher in the discordant group (51.8% ± 0.06% vs 31.2% ± 0.05%, P < .001). CONCLUSIONS: Even in the patients with documented chordae rupture, the PISA method alone resulted in inappropriate overestimation of MR severity in a significant proportion of patients. Thus, an additive quantitative method is absolutely necessary in patients with a small LVEDV or narrow PISA angle.

Impact of a Geometric Correction for Proximal Flow Constraint on the Assessment of Mitral Regurgitation Severity Using the Proximal Flow Convergence Method.

BACKGROUND: Overestimation of the severity of mitral regurgitation (MR) by the proximal isovelocity surface area (PISA) method has been reported. We sought to test whether angle correction (AC) of the constrained flow field is helpful to eliminate overestimation in patients with eccentric MR. METHODS: In a total of 33 patients with MR due to prolapse or flail mitral valve, both echocardiography and cardiac magnetic resonance image (CMR) were performed to calculate regurgitant volume (RV). In addition to RV by conventional PISA (RVPISA), convergence angle (α) was measured from 2-dimensional Doppler color flow maps and RV was corrected by multiplying by α/180 (RVAC). RV measured by CMR (RVCMR) was used as a gold standard, which was calculated by the difference between total stroke volume measured by planimetry of the short axis slices and aortic stroke volume by phase-contrast image. RESULTS: The correlation between RVCMR and RV by echocardiography was modest [RVCMR vs. RVPISA (r = 0.712, p < 0.001) and RVCMR vs. RVAC (r = 0.766, p < 0.001)]. However, RVPISA showed significant overestimation (RVPISA - RVCMR = 50.6 ± 40.6 mL vs. RVAC - RVCMR = 7.7 ± 23.4 mL, p < 0.001). The overall accuracy of RVPISA for diagnosis of severe MR, defined as RV ≥ 60 mL, was 57.6% (19/33), whereas it increased to 84.8% (28/33) by using RVAC (p = 0.028). CONCLUSION: Conventional PISA method tends to provide falsely large RV in patients with eccentric MR and a simple geometric AC of the proximal constraint flow largely eliminates overestimation.

In vivo assessment of aortic root geometry in normal controls using 3D analysis of computed tomography.

AIMS: Understanding normal asymmetry in the aortic root could aid in the development of new surgical repair techniques or devices with improved haemodynamic performance. The purpose of this study was to assess geometric asymmetry and age-related changes in the normal aortic root using 3D computed tomography. METHODS AND RESULTS: The institutional review board approved this retrospective study of 130 normal subjects (mean age, 51.4 years; 58 men). Specialized 3D software measured individual cusp sinus volumes (CSVs), cusp surface areas (CSAs), and intercommissural distances (ICDs). Age-related aortic root changes were evaluated with simple correlation, ANOVA test among age groups, and multivariable linear regression analyses. The CSV and CSA of left coronary cusp (LCC) were significantly smaller than those of right coronary cusp (RCC) and non-coronary cusp (NCC) (both, P < 0.001) in all age groups. The mean ratios of RCC or NCC-to-LCC were 1.38 and 1.36 for CSV, 1.19 and 1.20 for CSA, and 1.21 and 1.06 for ICD, respectively. The CSV and ICD increased in older age with weak-to-moderate correlation coefficients in both men and women. By multivariable linear regression, CSVs and ICDs of all cusps showed a positive correlation with age (P < 0.05), and the female gender was associated with a smaller size of the CSV and CSA. CONCLUSIONS: The LCC was significantly smaller than the other two cusps, and the aortic root size increased with age.

Diagnostic accuracy and cost-effectiveness of a pocket-sized transthoracic echocardiographic imaging device.

BACKGROUND: The recently introduced pocket-sized portable transthoracic echocardiography (pTTE) is accurate for measurement of cardiac chamber size and function as well as for assessment of valvular regurgitation. This study aimed to compare the diagnostic accuracy of the pocket-sized pTTE with the standard TTE (sTTE) and assess its cost-effectiveness. HYPOTHESIS: The use of pocket-sized pTTE, as an initial screening tool, may be feasible, accurate and cost-effective in the diagnostic strategy of cardiac abnormalities. METHODS: The study subjects were 200 patients scheduled for sTTE and an electrocardiogram (ECG). Each patient underwent pTTE examination with the Vscan (GE Medical Systems, Milwaukee, WI) immediately after sTTE. The findings of pTTE and the ECG were compared with the results of sTTE. Cost-effectiveness was calculated. RESULTS: There was a strong agreement in the detection of abnormal findings between pTTE and sTTE (agreement = 90%), whereas the agreement between the ECG and sTTE was 65%. When pTTE or the ECG was used as an initial screening tool prior to sTTE, similar cost reduction was obtained (approximately 30%) by reducing the number of referrals for sTTE. However, the negative predictive value of a diagnostic strategy with pTTE (92%) was superior to that with an ECG (67%). CONCLUSIONS: This study demonstrates that the pocket-sized pTTE provides accurate detection of cardiac structural and functional abnormalities beyond the ECG. In addition, the use of pTTE as an initial screening tool prior to sTTE is cost-effective, suggesting that the pocket-sized pTTE is poised to alter the current diagnostic strategy in clinical practice.

Assessment of papillary muscle function in patients with inferior wall myocardial infarction using Doppler tissue imaging.

OBJECTIVES: We sought to assess the relationship between infarct status and systolic contractile function of papillary muscle (PM) for patients with inferior wall myocardial infarction (MI). METHODS: Peak systolic velocity (V) of posteromedial PM, systolic strain (epsilon) of posteromedial PM (epsilonPM), V of adjacent inferior wall, and of adjacent inferior wall (epsilonW) were calculated from color Doppler tissue imaging images obtained at apical views in 25 patients with inferior MI and in 13 healthy control subjects. All 25 patients with MI underwent magnetic resonance imaging to assess the infarct status of PM. RESULTS: Compared with the control subjects, patients with MI had significantly lower V of adjacent inferior wall (5.0 +/- 0.8 vs 4.4 +/- 1.1 cm/s, P = .049) and V of posteromedial PM (4.9 +/- 0.8 vs 4.0 +/- 1.2 cm/s, P = .005), and less systolic deformation, as demonstrated by epsilonW (-17 +/- 3 vs -6 +/- 5%, P < .001) and epsilonPM (-24 +/- 5 vs -11 +/- 6%, P < .001). There was a weak positive correlation between epsilonW and epsilonPM (r = 0.393, P = .052) for patients with MI. Magnetic resonance imaging showed total infarct of PM in 14 patients (group A), with the remaining 11 revealing either normal perfusion or partial infarct of PM (group B). Although epsilonW was similar in groups A and B (-5 +/- 5% vs -8 +/- 6%, P = .20), epsilonPM was significantly lower in group B (-7 +/- 4% vs -16 +/- 4%, P = .004). CONCLUSIONS: In patients with inferior wall MI, infarct status of the PM is variable and determines its systolic contractile function, which can be quantified by epsilon measurement using Doppler tissue imaging.

Intravascular ultrasound assessment of patterns of arterial remodeling in the absence of significant reference segment plaque burden in patients with coronary artery disease.

OBJECTIVES: We evaluated the impact of reference vessel segment plaque burden on lesion remodeling. Intravascular ultrasound (IVUS) assessment of lesion remodeling compares lesions to reference segments. However, reference segments are rarely disease-free and, therefore, have also undergone remodeling changes. METHODS: Pre-intervention IVUS was obtained in 274 patients with right coronary artery lesions selected because the right coronary artery has less tapering and fewer side branches than the left anterior descending or left circumflex artery. Standard IVUS definitions were used. Patients were divided according to reference vessel segment plaque burden: group A (minimal reference disease, n = 91), both proximal and distal reference plaque burden <20%; group B (n = 91), either proximal or distal reference plaque burden 20% to 40% but both < or =40%; and group C (n = 92), either proximal or distal reference plaque burden >40%. RESULTS: The remodeling index measured 0.98 +/- 0.16 in group A (range, 0.68 to 1.47), 1.04 +/- 0.18 in group B (range, 0.67 to 1.91), and 1.04 +/- 0.15 in group C (range, 0.74 to 1.70), analysis of variance p = 0.0208 (p = 0.0234 group A vs. group B and p = 0.0012 group A vs. group C, but p = 0.8 group B vs. group C). Positive, intermediate, and negative remodeling were observed in 24 (26%), 24 (26%), and 43 lesions (48%) in group A; 36 (40%), 28 (30%), and 27 lesions (30%) in group B; and 34 (37%), 39 (42%), and 19 lesions (21%) in group C, respectively (p = 0.0022). CONCLUSIONS: Negative remodeling occurs commonly in coronary lesions with minimal reference segment disease. Negative remodeling is not just an "artifact" introduced by comparing lesions to diseased reference segments.