Pohoey Fan

Can two-dimensional echocardiography and Doppler color flow mapping identify the need for tricuspid valve repair?

Tricuspid regurgitation severity was assessed preoperatively with Doppler color flow mapping and these assessments were compared with surgical findings in 90 patients undergoing mitral or aortic valve replacement, or both. Group I (n = 52) required tricuspid valve annuloplasty because tricuspid regurgitation was judged intraoperatively to be severe; in Group II (n = 38), tricuspid valve annuloplasty was not performed because tricuspid regurgitation was judged intraoperatively not to be severe. With use of the apical four chamber and parasternal short-axis imaging planes, the severity of tricuspid regurgitation by Doppler color flow mapping was assessed by comparing the maximal area of tricuspid regurgitant signals with the right atrial area taken in the same frame in which the maximal tricuspid regurgitant signals were noted. This ratio was found to be greater than or equal to 34% (mean 50.2 +/- 11.8%) in 50 (96%) of 52 patients in Group I and less than 34% (mean 27.5 +/- 6.9%) in 36 (95%) of 38 patients in Group II (p less than 0.001). The maximal diastolic tricuspid anulus diameter measured with the same two-dimensional imaging planes was greater than or equal to mm/m2 body surface area (mean 26.7 +/- 5.2 mm/m2) in 46 patients (88%) in Group I and less than 21 mm/m2 (mean 17.8 +/- 2.5 mm/m2) in 36 patients (95%) in Group II (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Doppler color flow mapping in the evaluation of prosthetic mitral and aortic valve function

Doppler color flow mapping and color-guided conventional Doppler studies were performed on 119 patients with 126 prosthetic valves (mitral alone in 60, aortic alone in 52 and both mitral and aortic in 7 patients) within 2 weeks of the catheterization study or surgery, or both. The mean pressure gradients derived by color-guided continuous wave Doppler ultrasound correlated well with those obtained at catheterization for both the tissue and mechanical mitral and aortic prostheses (r = 0.85 to 0.87). For the effective prosthetic orifice areas, better correlation with catheterization results were obtained with the tissue mitral (r = 0.94) and tissue aortic (r = 0.87) prostheses than with the mechanical mitral (r = 0.79) and mechanical aortic (r = 0.76) prostheses. The maximal width of the color flow signals at their origin from the tissue mitral prostheses also correlated well with the effective prosthetic orifice area at catheterization (r = 0.81). Doppler color flow mapping identified prosthetic valvular regurgitation with a sensitivity and specificity of 89% and 100%, respectively, for the mitral and 92% and 83% for the aortic prostheses. There was complete agreement between the Doppler color flow mapping and angiographic grading of the severity of prosthetic valvular regurgitation in 90% of mitral and 73.5% of the aortic regurgitant prostheses with under- or overestimation by greater than 1 grade in only two cases. Valvular and paravalvular regurgitation was correctly categorized by Doppler color flow mapping in relation to the surgical findings in 94% of the mitral and 80.5% of the aortic prostheses.

Reproducibility of two-dimensional exercise echocardiography

To determine the reproducibility of two-dimensional exercise echocardiography, duplicate studies were performed on the same patients a median of 14 days apart. Because measurements are operator-dependent, interobserver variability was calculated for two experienced readers who interpreted the findings independently in a blinded manner. A high degree of interobserver agreement was found in evaluation of both ejection fraction measurements and wall motion abnormalities. Readings for ejection fraction immediately after exercise taken on different days could be estimated within 4% of the values measured in the first test; similarly measured wall motion score index was within 6% of that in the first test. Ejection fractions and wall motion scores were highly correlated between tests 1 and 2. The correlation coefficients between tests 1 and 2 were 0.92 for both the pre- and postexercise ejection fractions and 0.98 for both the pre- and postexercise wall motion scores. Quantitative two-dimensional echocardiography immediately after exercise is highly reproducible, providing a valuable tool for assessing serial changes in left ventricular function.

Live/real time three-dimensional transthoracic echocardiographic assessment of tricuspid valve pathology: incremental value over the two-dimensional technique.

Twenty‐nine patients with different tricuspid valve (TV) pathologies were studied by both two‐dimensional transthoracic (2DTTE) and live/real time three‐dimensional transthoracic echocardiography (3DTTE). A major contribution of 3DTTE over 2DTTE was the en face visualization of all three leaflets of the TV in all patients. This allowed accurate assessment of TV orifice area in patients with TV stenosis and carcinoid disease. Loss of TV leaflet tissue, defects in TV leaflets and size of TV systolic non‐coaptation could also be delineated and resulted in identifying the mechanism of tricuspid regurgitation (TR) in patients with Ebsteins anomaly and rheumatic heart disease. Prolapse of TV leaflets could also be well visualized and enabled us to develop a schema for systematic assessment of individual segment prolapse which could help in surgical planning. The exact sites of chordae rupture in patients with flail TV as well as right ventricular papillary muscle rupture could be well seen by 3DTTE. 3DTTE also permitted sectioning of various TV masses for more specific diagnosis of their nature. In addition, color Doppler 3DTTE provided an estimate of quantitative evaluation of TR severity, since the exact shape and size of the vena contracta could be accurately assessed. In conclusion, our preliminary experience with 3DTTE has demonstrated substantial incremental value over 2DTTE in the assessment of various TV pathologies.

Usefulness of Live/Real Time Three‐Dimensional Transthoracic Echocardiography in the Identification of Individual Segment/Scallop Prolapse of the Mitral Valve

In this report, we present 34 patients in whom surgical intervention was undertaken for severe mitral insufficiency due to mitral valve prolapse (MVP). Location and severity of MVP and regurgitation were assessed preoperatively by live/real time three‐dimensional transthoracic echocardiography and closely agreed with the surgical findings.

Color-guided Doppler echocardiographic assessment of aortic valve stenosis

The severity of valvular aortic stenosis was assessed by Doppler color flow mapping in 100 consecutive patients who underwent successful cardiac catheterization within 2 weeks of the Doppler study. The maximal width of the aortic stenosis jet seen in 61 of these patients (Group A) was measured at the aortic valve. Color-guided continuous wave Doppler examination was used to measure the mean transaortic pressure gradient, and the aortic valve area was estimated using the simplified continuity equation. The aortic stenosis jet was not seen in 39 patients (Group B), and the mean pressure gradient and aortic valve area in these patients were assessed by conventional Doppler echocardiography alone. The mean pressure gradient obtained by continuous wave Doppler study and cardiac catheterization in the 61 Group A patients correlated well (r = 0.90); the correlation was lower in the 39 Group B patients (r = 0.70). The overall correlation for the combined Groups A and B was good (r = 0.82). The aortic valve area estimated by continuous wave Doppler study and cardiac catheterization in 54 Group A patients correlated well (r = 0.92); the correlation in 22 Group B patients was lower (r = 0.71). The correlation for all 76 patients (Groups A and B) was good (r = 0.80). The maximal aortic stenosis jet width also correlated well with the aortic valve area estimated at catheterization in 54 patients (r = 0.90). Group C represented an additional 14 patients in whom the left ventricle could not be entered during cardiac catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of Multiplane and Biplane Transesophageal Echocardiography in the Assessment of Aortic Stenosis

The aim of the study was to compare the accuracy of multiplane transesophageal echocardiography (TEE) with the more conventional biplane technique in the direct assessment of aortic valve area in patients with aortic stenosis. Short-axis images of the aortic valve adequate for measuring aortic valve area were obtained in all 81 patients studied by multiplane TEE but in only 56 of 64 patients (88%) using the biplane approach. The correlation coefficient for aortic valve area determined by multiplane TEE (r = 0.89; SEE = 0.04 cm2) was higher (p < 0.01) than biplane TEE (r = 0.74; SEE = 0.06 cm2). Correlations were higher for bicuspid valves (multiplane, r = 0.93; biplane, r = 0.75) than tricuspid valves (multiplane, r = 0.87; biplane, r = 0.75). Our study has demonstrated the superiority of multiplane TEE to both biplane TEE and transthoracic echocardiography (TTE) in the direct evaluation of aortic valve area in patients with aortic stenosis.

Influence of longer term left ventricular assist device support on valvular regurgitation.

The authors previously published data that describe acute alterations in ventricular dimensions and in the severity of mitral and tricuspid regurgitation (MR/TR) after initiation of left ventricular assist device (LVAD) pumping. In the current study, measurements of ventricular size and regurgitant jet area acquired after LVAD implantation are presented. Eight patients had LVAD implanted pending cardiac transplantation (duration of assist 70-279 days; mean, 162 +/- 29 days). Echocardiograms were obtained at the time of LVAD implant and later during LVAD support (mean time for late echo, 95 +/- 32 days post-implant). Comparisons of pre-implant with late post-implant data showed: increased TR jet area (4.8 +/- 1.0 cm2 vs. 8.0 +/- 1.7 cm2 P < 0.05); increased right ventricular (RV) end-systolic dimension (31 +/- 4 vs 40 +/- 5 mm, P < 0.05); and increased RV end-diastolic dimension (35 +/- 4 vs. 45 +/- 5 mm, P < 0.065). Decreased MR jet area and decreased LV dimensions (P < 0.05) also were noted on comparison of pre-implant and late post-implant data. There were no significant differences between any immediate post-implant and late post-implant echocardiographic measurements. No patient had clinical evidence of RV failure. LV mechanical assist causes an acute increase in TR, presumably by volume loading the RV. TR and RV enlargement persisted but did not discernibly worsen on subsequent post-implant echocardiograms. LV dimensions and MR remained less than the pre-implant values on later post-implant determinations.

Comparison of various agents in contrast enhancement of color doppler flow images: An in vitro study

The commercially manufactured contrast agents, Echovist and Albunex, were compared with sonicated conventional agents, indocyanine green, 29% renografin-60, 0.9% normal saline and 25% mannitol in their ability to enhance color Doppler flow signals. In a pneumatically regulated pulsatile flow system, a glycerine, saline (0.9%) and sand (5 microns particle size) solution was imaged using a 2.5 MHz phased-array transducer. Four different flow velocities (0.40, 0.35, 0.30 and 0.25 m/s) as measured by color Doppler guided pulse Doppler were utilized. All color Doppler settings were kept constant throughout the study. Utilizing a power injector, four different volumes (1.0, 1.5, 2.0 and 2.5 mL) of each contrast agent were injected into the flow medium at various transducer angles (20, 30, 40 and 60 degrees) and various distances from the transducer (3.38, 5.5, 6.76 cm). For Echovist and Albunex, several concentrations varying from 2% to 100% were used. Keeping instrument settings constant, color flow areas obtained before and after each contrast injection were planimeterized and the percent increase in the color flow area computed and compared. At full (100%) concentration, 20 degrees transducer angle and a flow velocity of 0.40 m/s, the maximum increase in the color flow area was 568%, 251%, 180%, 110%, 71%, and 38% for Echovist, Albunex, sonicated indocyanine green, renografin, normal saline and mannitol, respectively. However, a significant reduction in the degree of color flow enhancement was observed, with decreases in the concentration of these agents, and increases in the Doppler beam incident angle or distance from the transducer. Increasing the flow velocity of the medium into which contrast was injected did not produce significant changes in the contrast enhancement effect for all agents except Echovist. Increasing the injection volume significantly increased the color flow area for sonicated agents but not for Echovist or Albunex. This preliminary in vitro study shows that the commercially manufactured contrast agents, Echovist and Albunex, are much superior to sonicated conventional contrast agents in the enhancement of color Doppler flow signals. Of the sonicated agents, indocyanine green had the best enhancement capability.

Color Doppler velocity accuracy proximal to regurgitant orifices: influence of orifice aspect ratio

Many noninvasive methodologies used for the accurate evaluation of valvular regurgitation require precise velocity measurements from ultrasound instruments. Previous studies have indicated that velocity measurements from color Doppler (CD) instruments are susceptible to errors due to the interaction of the ultrasound beam and the proximal orifice flow field. This study examined the influence of high aspect ratio (AR) orifices on the CD velocity error. Center line velocity error distributions for orifices ranging from 7.07 to 78.5 mm2, varying in shape from circular to an AR = 8 ellipse, were evaluated using a numerical model of the ultrasound beam and the simulated regurgitant flow field. An in vitro study was also performed and confirmed the findings of the numerical model. The study showed that increasing AR does not significantly change the error characteristics. The study confirmed that orifice size is the dominant factor in the error distribution, and that corrections speculated for circular orifices can be extended to elliptical orifices without significant errors.