Journal of the American Society of Echocardiography. 2010; 23(6):581-590

Giovanni Di Salvo, Giuseppe Pacileo, Giuseppe Limongelli, Luca Baldini, Alessandra Rea, Marina Verrengia, Antonello D'Andrea, Maria Giovanna Russo, Raffaele Calabrò

OBJECTIVES: The mechanism of sudden death in hypertrophic cardiomyopathy (HCM) is ventricular tachyarrhythmia emanating from myocyte disarray, fibrosis, and inhomogeneity in intramyocardial activation. Tissue synchronization imaging (TSI) allows the measurement of regional delay, while two-dimensional strain can be used to identify myocardial fibrosis. The aim of this study was to assess the relationship between new ultrasonically derived parameters and nonsustained ventricular tachycardia (NSVT) in patients with HCM.

METHODS: Ninety-three patients with HCM (mean age, 36 +/- 16 years) and 30 patients with hypertension with secondary left ventricular (LV) hypertrophy (mean age, 42 +/- 10 years; 65% men) were studied. All underwent standard echocardiographic, TSI, and two-dimensional strain examinations. Patients were followed every 3 months for 2 years. Holter monitoring was performed every 3 months. The primary endpoint was the occurrence of NSVT.

RESULTS: Twenty-four patients (26%) had >1 episode of NSVT. Patients with NSVT had a higher value of maximal LV thickness (22 +/- 6 vs 19 +/- 5 mm, P = .04). There were no significant associations between NSVT on Holter monitoring and LV outflow gradient, New York Heart Association class, syncope, and medical therapy. N-terminal pro-brain natriuretic peptide values were significantly (P = .01) higher in patients with NSTV (1034 +/- 1088 vs 561 +/- 593 pg/mL). Patients with HCM and NSVT had (1) similar values on TSI-studied parameters to patients without NSVT, (2) significant reductions in basal and mid septal strain and in basal anterior-septal strain, and (3) more frequently peak systolic strain >-10% (P < .0001). In multivariate analysis, the presence of >3 LV segments with longitudinal two-dimensional strain > -10% (sensitivity, 81%; specificity, 97.1%; area under the curve, 0.944; P < .0001) was an independent predictor of NSVT.

CONCLUSIONS: Using a simple, inexpensive, easily available, and bedside-usable tool, it was possible to recognize with good sensitivity and specificity patients with HCM at higher risk for NSVT.

PMID: 20362415

J Am Coll Cardiol Img. 2010; 3(3):227-234

Muhammad Ashraf, Andriy Myronenko, Thuan Nguyen, Akio Inage, Wayne Smith, Robert I. Lowe, Karl Thiele, Carol A. Gibbons Kroeker, John V. Tyberg, Jeffrey F. Smallhorn, David J. Sahn, Xubo Song

OBJECTIVES: To compute left ventricular (LV) twist from 3-dimensional (3D) echocardiography. LV twist is a sensitive index of cardiac performance. Conventional 2-dimensional based methods of computing LV twist are cumbersome and subject to errors.

METHODS: We studied 10 adult open-chest pigs. The pre-load to the heart was altered by temporary controlled occlusion of the inferior vena cava, and myocardial ischemia was produced by ligating the left anterior descending coronary artery. Full-volume 3D loops were reconstructed by stitching of pyramidal volumes acquired from 7 consecutive heart beats with electrocardiography gating on a Philips IE33 system (Philips Medical Systems, Andover, Massachusetts) at baseline and other steady states. Polar coordinate data of the 3D images were entered into an envelope detection program implemented in MatLab (The MathWorks, Inc., Natick, Massachusetts), and speckle motion was tracked using nonrigid image registration with spline-based transformation parameterization. The 3D displacement field was obtained, and rotation at apical and basal planes was computed. LV twist was derived as the net difference of apical and basal rotation. Sonomicrometry data of cardiac motion were also acquired from crystals anchored to epicardium in apical and basal planes at all states.

RESULTS: The 3D dense tracking slightly overestimated the LV twist, but detected changes in LV twist at different states and showed good correlation (r = 0.89) when compared with sonomicrometry-derived twist at all steady states. In open chest pigs, peak cardiac twist was increased with reduction of pre-load from inferior vena cava occlusion from 6.25° ± 1.65° to 9.45° ± 1.95°. With myocardial ischemia from left anterior descending coronary artery ligation, twist was decreased to 4.90° ± 0.85° (r = 0.8759).

CONCLUSIONS: Despite lower spatiotemporal resolution of 3D echocardiography, LV twist and torsion can be computed accurately.

PMID: 20223418

J Am Coll Cardiol Img. 2010; 3(3):235-243

Simon Biner, Asim Rafique, Farhad Rafii, Kirsten Tolstrup, Omid Noorani, Takahiro Shiota, Swaminatha Gurudevan, Robert J. Siegel

OBJECTIVES: The aim of this study was to evaluate the interobserver agreement of proximal isovelocity surface area (PISA) and vena contracta (VC) for differentiating severe from nonsevere mitral regurgitation (MR). Recommendation for MR evaluation stresses the importance of VC width and effective regurgitant orifice area by PISA measurements. Reliable and accurate assessment of MR is important for clinical decision making regarding corrective surgery. We hypothesize that color Doppler-based quantitative measurements for classifying MR as severe versus nonsevere may be particularly susceptible to interobserver agreement.

METHODS: The PISA and VC measurements of 16 patients with MR were interpreted by 18 echocardiologists from 11 academic institutions. In addition, we obtained quantitative assessment of MR based on color flow Doppler jet area.

RESULTS: The overall interobserver agreement for grading MR as severe or nonsevere using qualitative and quantitative parameters was similar and suboptimal: 0.32 (95% confidence interval [CI]: 0.1 to 0.52) for jet area–based MR grade, 0.28 (95% CI: 0.11 to 0.45) for VC measurements, and 0.37 (95% CI: 0.16 to 0.58) for PISA measurements. Significant univariate predictors of substantial interobserver agreement for: 1) jet area–based MR grade was functional etiology (p = 0.039); 2) VC was central MR (p = 0.013) and identifiable effective regurgitant orifice (p = 0.049); and 3) PISA was presence of a central MR jet (p = 0.003), fixed proximal flow convergence (p = 0.025), and functional etiology (p = 0.049). Significant multivariate predictors of raw interobserver agreement 80% included: 1) for VC, identifiable effective regurgitant orifice (p = 0.035); and 2) for PISA, central regurgitant jet (p = 0.02).

CONCLUSIONS: The VC and PISA measurements for distinction of severe versus nonsevere MR are only modestly reliable and associated with suboptimal interobserver agreement. The presence of an identifiable effective regurgitant orifice improves reproducibility of VC and a central regurgitant jet predicts substantial agreement among multiple observers of PISA assessment.

PMID: 20223419

JACC Imaging. 2010; 2(3):132-140

Olusegun Oyenuga, Hideyuki Hara, Hidekazu Tanaka, Han-Na Kim, Evan C. Adelstein, Samir Saba, John Gorcsan, III

OBJECTIVES: To test the hypothesis that echocardiographic dyssynchrony may assist in the selection of patients with borderline QRS duration for cardiac resynchronization therapy (CRT). Although echocardiographic dyssynchrony is currently not recommended to select patients with QRS duration widening for CRT, its utility in patients with borderline QRS widening is unclear.

METHODS: Of 221 consecutive heart failure patients with an ejection fraction (EF) 35% referred for CRT, 86 had a borderline QRS duration of 100 to 130 ms (115 ± 8 ms) and 135 patients had wide QRS >130 ms (168 ± 26 ms). Dyssynchrony was assessed using interventricular mechanical delay, tissue Doppler imaging longitudinal velocity opposing wall delay, and speckle tracking radial strain for septal to posterior wall delay. Response to CRT was defined as 15% increase in EF, and reverse remodeling as 10% decrease in end-systolic volume.

RESULTS: There were 201 patients with baseline quantitative echocardiographic data available, and 187 with follow-up data available 8 ± 5 months after CRT. A smaller proportion of borderline QRS duration patients (53%) were EF responders compared with 75% with widened QRS (p < 0.05). Interventricular mechanical delay 40 ms and opposing wall delay 65 ms were predictive of EF response in the wide QRS duration group, but not the borderline QRS duration group. Speckle tracking radial dyssynchrony 130 ms, however, was predictive of EF response in both wide QRS interval patients (88% sensitivity, 74% specificity) and borderline QRS interval patients (79% sensitivity, 82% specificity) and associated reverse remodeling with reduction in end-systolic volume (p < 0.0005).

CONCLUSIONS: Radial dyssynchrony by speckle tracking strain was associated with EF and reverse remodeling response to CRT in patients with borderline QRS duration and has the potential to assist with patient selection.

PMID: 20159638

JACC Imaging. 2010; 2(3):121-131

Manish Bansal, Leanne Jeffriess, Rodel Leano, Julie Mundy, Thomas H. Marwick

OBJECTIVES: Comparison of myocardial tissue-velocity imaging (TVI) and speckle-tracking echocardiography (STE) for prediction of viability at dobutamine echocardiography (DbE). Use of TVI-based strain imaging during DbE may facilitate the prediction of myocardial viability but has technical limitations. STE overcomes these but requires evaluation for prediction of viability.

METHODS: We studied 55 patients with ischemic heart disease and left ventricular systolic dysfunction (left ventricular ejection fraction <0.45) who were undergoing DbE for assessment of myocardial viability and who subsequently underwent myocardial revascularization. TVI was used to measure longitudinal end-systolic strain (longS) and peak systolic strain rate (SR) at rest and at low-dose dobutamine (LDD). Longitudinal, radial, and circumferential strain and strain rate were measured with STE. Segmental functional recovery was defined by improved wall-motion score on side-by-side comparison of echocardiographic images before and 9 months after revascularization and areas under the receiver operator characteristic curves were used to compare methods.

RESULTS: Of the 375 segments with abnormal resting function, 154 (41%) showed functional recovery. Only circumferential resting and low-dose STE strain and low-dose longitudinal strain and SR predicted functional recovery independent of wall-motion analysis. Among different strain parameters, only TVI-based longitudinal end-systolic strain and peak systolic SR at LDD had incremental value over wall-motion analysis (areas under the receiver operator characteristic curves of 0.79, 0.79, and 0.74, respectively). STE measurements of strain and SR identified viability only in the anterior circulation, whereas TVI strain and SR accurately identified viability in both anterior and posterior circulations.

CONCLUSIONS: Combination of TVI or STE methods with DbE can predict viability, with TVI strain and SR at LDD being the most accurate. TVI measures can predict viability in both anterior and posterior circulations, but STE measurements predict viability only in the anterior circulation.

PMID: 20159637

JACC Imaging. 2010; 1(3):1-9

Eun Joo Cho, MD, PhD, Giuseppe Caracciolo, MD, Bijoy K. Khandheria, MD, D. Eric Steidley, MD, Robert Scott, MD, Walter P. Abhayaratna, MD, Krishnaswamy Chandrasekaran, MD, Partho P. Sengupta, MD, DM

OBJECTIVES: We explored the incremental value of quantification of tissue Doppler (TD) velocity during the brief isovolumic contraction (IVC) phase of the cardiac cycle for the prediction of exercise performance in patients referred for cardiopulmonary exercise testing (CPET).  Experimental studies have shown that rapid left ventricular (LV) shape change during IVC is essential for optimal onset of LV ejection. However, the incremental value of measuring IVC velocities in clinical settings remains unclear.

METHODS: A total of 82 subjects (age 53 ± 14 years, 56 men) were studied with echocardiography and CPET. Reduced LV ejection fraction (EF) (EF <50%) was present in 38 (46%) subjects. Pulsed-wave annular TD velocities were averaged from the LV lateral and septal annulus during isovolumic contraction (IVCa), ejection, isovolumic relaxation, and early and late diastole (Aa) and compared with peak oxygen consumption (VO₂) and percentage of the predicted peak VO₂ (% predicted peak VO₂) obtained from CPET.

RESULTS: Patients with reduced EF had lower IVCa (6.3 vs. 4.5 cm/s, p = 0.04), ejection (7.7 vs. 5.5 cm/s, p < 0.001), and Aa velocities (7.9 vs. 6.6 cm/s, p = 0.04). Similarly, % predicted peak VO₂ was lower in patients with reduced EF (52.9% vs. 73.1%, p < 0.001) and correlated with the variations in IVCa (r = 0.7, p = 0.001). Multivariate analysis of 2-dimensional and Doppler variables in the presence of reduced LV EF revealed only IVCa and Aa as independent predictors of % predicted peak VO₂ (r² = 0.612, p = 0.02 for IVCa and p = 0.009 for Aa). The overall performance of IVCa in the prediction of exercise capacity was good (area under the curve = 0.86, p < 0.001).

CONCLUSIONS: Assessment of TD-derived IVC and atrial stretch velocities provide independent prediction of exercise capacity in patients with reduced LV EF. Assessment of LV pre-ejectional stretch and shortening mechanics at rest may be useful for determining the myocardial functional reserve of patients with reduced EF.

PMID: