Marta Sitges

Outcome of patients with hypertrophic obstructive cardiomyopathy after percutaneous transluminal septal myocardial ablation and septal myectomy surgery.

OBJECTIVESnThis study was conducted to evaluate follow-up results in patients with hypertrophic obstructive cardiomyopathy (HOCM) who underwent either percutaneous transluminal septal myocardial ablation (PTSMA) or septal myectomy.nnnBACKGROUNDnControversy exists with regard to these two forms of treatment for patients with HOCM.nnnMETHODSnOf 51 patients with HOCM treated, 25 were treated by PTSMA and 26 patients via myectomy. Two-dimensional echocardiograms were performed before both procedures, immediately afterwards and at a three-month follow-up. The New York Heart Association (NYHA) functional class was obtained before the procedures and at follow-up.nnnRESULTSnInterventricular septal thickness was significantly reduced at follow-up in both groups (2.3 +/- 0.4 cm vs. 1.9 +/- 0.4 cm for septal ablation and 2.4 +/- 0.6 cm vs. 1.7 +/- 0.2 cm for myectomy, both p < 0.001). Estimated by continuous-wave Doppler, the resting pressure gradient (PG) across the left ventricular outflow tract (LVOT) significantly decreased immediately after the procedures in both groups (64 +/- 39 mm Hg vs. 28 +/- 29 mm Hg for PTSMA, 62 +/- 43 mm Hg vs. 7 +/- 7 mm Hg for myectomy, both p < 0.0001). At three-month follow-up, the resting PG remained lower in the PTSMA and myectomy groups (24 +/- 19 mm Hg and 11 +/- 6 mm Hg, respectively, vs. those before procedures, both p < 0.0001). The NYHA functional class was also significantly improved in both groups (3.5 +/- 0.5 vs. 1.9 +/- 0.7 for PTSMA, 3.3 +/- 0.5 vs. 1.5 +/- 0.7 for myectomy, both p < 0.0001).nnnCONCLUSIONSnBoth myectomy and PTSMA reduce LVOT obstruction and significantly improve NYHA functional class in patients with HOCM. However, there are benefits and drawbacks for each therapeutic method that must be counterbalanced when deciding on treatment for LVOT obstruction.

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

OBJECTIVESnThe 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).nnnBACKGROUNDnIn patients with HCM, LVOT velocity should change inversely with minimal A(LVOT) unless LVOT obstruction reduces the pumping capacity of the ventricle.nnnMETHODSnA 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.nnnRESULTSnReal-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).nnnCONCLUSIONSnThree-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.

Comparison of left ventricular diastolic function in obstructive hypertrophic cardiomyopathy in patients undergoing percutaneous septal alcohol ablation versus surgical myotomy/myectomy

Both percutaneous transcoronary alcohol septal reduction (ASR) and surgical myectomy are effective treatments to relieve left ventricular (LV) outflow tract obstruction in obstructive hypertrophic cardiomyopathy (HC). LV diastolic function was assessed by echocardiography in 57 patients with obstructive HC at baseline and 5 +/- 4 months after ASR (n = 37) or surgical myectomy (n = 20). LV outflow tract pressure gradient decreased from 65 +/- 40 to 23 +/- 21 mm Hg (p <0.01) after treatment. The ratio of the early-to-late peak diastolic LV inflow velocities, and the ratio of the early peak diastolic LV inflow velocity to the lateral mitral annulus early diastolic velocity determined by tissue Doppler imaging significantly decreased after the procedures (1.6 +/- 1.7 vs 1.0 +/- 0.7 and 15 +/- 8 vs 11 +/- 5, respectively), whereas LV inflow propagation velocity significantly increased (60 +/- 24 vs 71 +/- 36 cm/s). Left atrial size decreased from 29 +/- 7 to 25 +/- 6 cm(2) (p <0.05). Patients had a significant improvement in New York Heart Association functional class and in exercise performance. When comparing ASR with myectomy, no difference was found in the degree of change in any parameter of diastolic function. Thus, diastolic function indexes obtained by echocardiography changed after septal reduction interventions in patients with obstructive HC; this change was similar to that after surgical myectomy and ASR.

Left ventricular outflow tract mean systolic acceleration as a surrogate for the slope of the left ventricular end-systolic pressure-volume relationship.

OBJECTIVEnThe goal of this study was to analyze left ventricular outflow tract systolic acceleration (LVOT(Acc)) during alterations in left ventricular (LV) contractility and LV filling.nnnBACKGROUNDnMost indexes described to quantify LV systolic function, such as LV ejection fraction and cardiac output, are dependent on loading conditions.nnnMETHODSnIn 18 sheep (4 normal, 6 with aortic regurgitation, and 8 with old myocardial infarction), blood flow velocities through the LVOT were recorded using conventional pulsed Doppler. The LVOT(Acc) was calculated as the aortic peak velocity divided by the time to peak flow; LVOT(Acc) was compared with LV maximal elastance (E(m)) acquired by conductance catheter under different loading conditions, including volume and pressure overload during an acute coronary occlusion (n = 10). In addition, a clinically validated lumped-parameter numerical model of the cardiovascular system was used to support our findings.nnnRESULTSnLeft ventricular E(m) and LVOT(Acc) decreased during ischemia (1.67 +/- 0.67 mm Hg.ml(-1) before vs. 0.93 +/- 0.41 mm Hg.ml(-1) during acute coronary occlusion [p < 0.05] and 7.9 +/- 3.1 m.s(-2) before vs. 4.4 +/- 1.0 m.s(-2) during coronary occlusion [p < 0.05], respectively). Left ventricular outflow tract systolic acceleration showed a strong linear correlation with LV E(m) (y = 3.84x + 1.87, r = 0.85, p < 0.001). Similar findings were obtained with the numerical modeling, which demonstrated a strong correlation between predicted and actual LV E(m) (predicted = 0.98 [actual] -0.01, r = 0.86). By analysis of variance, there was no statistically significant difference in LVOT(Acc) under different loading conditions.nnnCONCLUSIONSnFor a variety of hemodynamic conditions, LVOT(Acc) was linearly related to the LV contractility index LV E(m) and was independent of loading conditions. These findings were consistent with numerical modeling. Thus, this Doppler index may serve as a good noninvasive index of LV contractility.

Interaliasing distance of the flow convergence surface for determining mitral regurgitant volume: A validation study in a chronic animal model

OBJECTIVESnWe aimed to validate a new flow convergence (FC) method that eliminated the need to locate the regurgitant orifice and that could be performed semiautomatedly.nnnBACKGROUNDnComplex and time-consuming features of previously validated color Doppler methods for determining mitral regurgitant volume (MRV) have prevented their widespread clinical use.nnnMETHODSnThirty-nine different hemodynamic conditions in 12 sheep with surgically created flail leaflets inducing chronic mitral regurgitation were studied with two-dimensional (2D) echocardiography. Color Doppler M-mode images along the centerline of the accelerating flow towards the mitral regurgitation orifice were obtained. The distance between the two first aliasing boundaries (interaliasing distance [IAD]) was measured and the FC radius was mathematically derived according to the continuity equation (R(calc) = IAD/(1 - radicalv(1)/v(2)), v(1) and v(2) being the aliasing velocities). The conventional 2D FC radius was also measured (R(meas)). Mitral regurgitant volume was then calculated according to the FC method using both R(calc) and R(meas). Aortic and mitral electromagnetic (EM) flow probes and meters were balanced against each other to determine the reference standard MRV.nnnRESULTSnMitral regurgitant volume calculated from R(calc) and R(meas) correlated well with EM-MRV (y = 0.83x + 5.17, r = 0.90 and y = 1.04x + 0.91, r = 0.91, respectively, p < 0.001 for both). However, both methods resulted in slight overestimation of EM-MRV (Delta was 3.3 +/- 2.1 ml for R(calc) and 1.3 +/- 2.3 ml for R(meas)).nnnCONCLUSIONSnGood correlation was observed between MRV derived from R(calc) (IAD method) and EM-MRV, similar to that observed with R(meas) (conventional FC method) and EM-MRV. The R(calc) using the IAD method has an advantage over conventional R(meas) in that it does not require spatial localization of the regurgitant orifice and can be performed semiautomatedly.

Impact of temporal resolution on flow quantification by real-time 3D color Doppler echocardiography: numerical modeling and animal validation study

Real-time, 3D color Doppler echocardiography (RT3D) is capable of quantifying flow at the LV outflow tract (LVOT). However, previous works have found significant underestimation for flow rate estimation due to finite scanning time (ST) of the color Doppler. The authors have, therefore, developed a mathematical model to correct the impact of ST on flow quantification and validated it by an animal study. Scanning time to cover the entire cross-sectional image of the LVOT was calculated as 60 ms, and the underestimation due to temporal averaging effect was predicted as 18/spl plusmn/7%. In the animal experiment, peak flow rates were obtained by spatially integrating the velocity data front the cross-sectional color images of the LVOT. By applying a correction factor, there was an excellent agreement between reference flow rate by an electromagnetic flow meter and RT3D (A/spl uml/=-5.6 ml/s, r=0.93), which was significantly better than without correction (p<0.001). Real-time, color 3D echocardiography was capable of quantifying flow accurately by applying the mathematical correction.