Regurgitant flow in cardiac valve prostheses: diagnostic value of gradient echo nuclear magnetic resonance imaging in reference to transesophageal two-dimensional color Doppler echocardiography.

Gradient echo nuclear magnetic resonance (NMR) imaging and transesophageal two-dimensional color Doppler echocardiography are flow-sensitive techniques that have been used in the diagnosis and grading of valvular regurgitation. To define the diagnostic value of gradient echo NMR imaging in the detection of regurgitant flow in cardiac valve prostheses and the differentiation of physiologic leakage flow from pathologic transvalvular or paravalvular leakage flow, 47 patients with 55 valve prostheses were examined. Color Doppler transesophageal echocardiography was used for comparison. Surgical confirmation of findings was obtained in 11 patients with 13 valve prostheses. Gradient echo NMR imaging showed regurgitant flow in 37 of 43 valves with a jet seen on transesophageal echocardiography and it detected physiologic leakage flow in 4 additional valves. There was 96% agreement between the two methods in distinguishing between physiologic and pathologic leakage flow. The methods differed on jet origin of pathologic leakage flow in six prostheses. The degree of regurgitation was graded by both NMR imaging and transesophageal echocardiography, according to the area of the regurgitant jet visualized; gradings were identical for 75% of valve prostheses. Quantification of jet length and area showed a good correlation between the two methods (r = 0.85 and r = 0.91, respectively). Gradient echo NMR imaging is a useful noninvasive technique for the detection, localization and estimation of regurgitant flow in cardiac valve prostheses. However, because transesophageal echocardiography is less time-consuming and less expensive, gradient echo NMR imaging is unlikely to displace transesophageal echocardiography and should be used only in the occasional patient who cannot be adequately imaged by echocardiography.     

Transesophageal Doppler color flow imaging in the detection of native and Bj?rk-Shiley mitral valve regurgitation

Regurgitant blood flow of mitral valves was studied by transesophageal Doppler color flow echocardiographic imaging in 11 healthy volunteers (Group 1), 25 cardiac patients with a native mitral valve (Group 2), 10 patients with a normally functioning Bj?rk-Shiley mitral prosthesis without clinical evidence of mitral regurgitation (Group 3) and 10 patients with angiographic or surgical evidence of Bj?rk-Shiley mitral valve regurgitation (Group 4). Holosystolic regurgitant color jets were classified as type I or type II. The data were compared with results obtained with precordial techniques, i.e., continuous wave and Doppler color flow echocardiographic imaging (Groups 1 to 4) and left ventricular angiography or surgery (Groups 2 and 4). In Group 1, transesophageal Doppler color flow imaging revealed no mitral regurgitant flow in 7 of the 11 patients and a type I jet in 4 patients that was detected in only 1 patient by precordial techniques. In Group 2, angiography showed no mitral regurgitation in 20 patients and documented mitral regurgitation in 5. Transesophageal Doppler color flow imaging detected in 4 of the 20 patients a type I jet that was not visualized with precordial techniques in 2 patients. Type II jets were detected by the transesophageal technique in all five patients with proven mitral regurgitation and were also visualized with precordial echocardiography. All patients in Group 3 showed two identical type I jets that were not detected with precordial echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)     

The flail mitral valve: echocardiographic findings by precordial and transesophageal imaging and Doppler color flow mapping

To determine the echocardiographic and Doppler characteristics of mitral regurgitation associated with a flail mitral valve, precordial and transesophageal echocardiography with pulsed wave and Doppler color flow mapping was performed in 17 patients with a flail mitral valve leaflet due to ruptured chordae tendineae (Group I) and 22 patients with moderate or severe mitral regurgitation due to other causes (Group II). Echocardiograms were performed before or during cardiac surgery; cardiac catheterization was also performed in 28 patients (72%). Mitral valve disease was confirmed at cardiac surgery in all patients. By echocardiography, the presence of a flail mitral valve leaflet was defined by the presence of abnormal mitral leaflet coaptation or ruptured chordae. Using these criteria, transesophageal imaging showed a trend toward greater sensitivity and specificity than precordial imaging in the diagnosis of flail mitral valve leaflet. By Doppler color flow mapping, a flail mitral valve leaflet was also characterized by an eccentric, peripheral, circular mitral regurgitant jet that closely adhered to the walls of the left atrium. The direction of flow of the eccentric jet in the left atrium distinguished a flail anterior from a flail posterior leaflet. By transesophageal echocardiography with Doppler color flow mapping, the ratio of mitral regurgitant jet arc length to radius of curvature was significantly higher in Group I than Group II patients (5.0 +/- 2.3 versus 0.7 +/- 0.6, p less than 0.001); all of the Group I patients and none of the Group II patients had a ratio greater than 2.5.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of mitral regurgitation by Doppler echocardiography

The diagnosis and assessment of mitral regurgitation has been one of the main challenges for cardiac ultrasound. Imaging techniques (M-mode and two-dimensional echocardiography) provide direct morphologic and etiologic information of the evaluation of patients with suspected mitral regurgitation. The advent of cardiac Doppler increased tremendously the ability to evaluate mitral regurgitation noninvasively. Continuous-wave and pulsed Doppler have been found to be sensitive and specific in the detection of mitral regurgitation. The introduction of color flow Doppler simplified enormously the assessment of patients with suspected mitral regurgitation. The maximal regurgitant area and maximal regurgitant area corrected for left atrial size have become the most commonly used parameters to evaluate mitral regurgitation by color flow Doppler in the clinical setting. However, the color regurgitant jet area is highly dependent on anatomical, hemodynamic, and equipment factors. A new method, based on the proximal isovelocity surface area, is being evaluated and appears to be relatively independent of equipment factors. Transesophageal echocardiography has been shown to be exquisitely sensitive in the detection of mitral regurgitation. Quantitation of mitral regurgitation by transesophageal echocardiography is currently based on the maximal regurgitant area and this parameter appears to correlate closely with the angiographic degree of mitral regurgitation. Pulmonary venous flow analysis had been used in conjunction with color flow mapping for the evaluation of mitral regurgitation by transesophageal echocardiography. The presence of reversed systolic flow has been shown to be sensitive and specific for the diagnosis of severe mitral regurgitation. Patients with clinically difficult surface studies, flail mitral valve leaflets, and prosthetic mitral valve are best evaluated by the transesophageal approach with interrogation of pulmonary venous flow.     

Doppler color flow mapping in the diagnosis of ventricular septal rupture and acute mitral regurgitation after myocardial infarction

Fifty consecutive patients with a newly acquired systolic murmur and severe cardiac decompensation following a recent myocardial infarction (27 with an anterior and 23 with an inferior infarct) were studied by a combination of two-dimensional echocardiography, spectral Doppler and Doppler color flow mapping. The initial ultrasound study defined a ventricular septal rupture in 43 patients and severe isolated mitral regurgitation in 7 patients (5 with papillary muscle rupture and 2 with severe papillary muscle dysfunction). All 50 patients had subsequent confirmation of the diagnosis by either cardiac catheterization or surgical inspection, or both. Two-dimensional echocardiography alone directly visualized a septal defect in only 17 (40%) of the 43 patients with ventricular septal rupture. In all 43 patients the mitral valve appeared normal on imaging. In six of the seven patients with isolated mitral regurgitation, two-dimensional echocardiography correctly demonstrated the structural abnormality of the mitral valve (five with flail anterior leaflet and one with posterior leaflet prolapse). The addition of Doppler color flow mapping greatly improved the diagnostic information in both patient groups. In all 43 patients with ventricular septal rupture, Doppler color flow mapping demonstrated both an area of turbulent transseptal flow and a diagnostic systolic flow disturbance within the right ventricle. In the seven patients with isolated papillary muscle rupture or dysfunction, Doppler color flow mapping not only demonstrated the presence of mitral regurgitation in all cases, but also identified the specific mitral leaflet abnormality by defining the direction of the regurgitant jet.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of transthoracic and transesophageal assessment of prosthetic valve dysfunction

Transesophageal echocardiography has added another dimension to the assessment of prosthetic valve dysfunction with high-resolution images that allow for more detailed structural evaluation of tissue and mechanical valves. This study is a retrospective analysis of 140 prosthetic valves (90 tissue, 50 mechanical) in the mitral (89), aortic (45), and tricuspid (6) position in 116 patients studied by transthoracic and transesophageal echocardiography techniques. Transesophageal echocardiography was consistently better than the transthoracic technique in the evaluation of structural abnormalities of tissue valves in the mitral and aortic positions with respect to leaflet thickening, prolapse, flail, and vegetations. With transesophageal echocardiography, five tissue mitral valves had flail leaflets that were not identified by the transthoracic technique. Transesophageal echocardiography was better than transthoracic in the detection, quantification, and localization of prosthetic mitral regurgitation. Physiological mitral regurgitation was detected in 31 valves by transesophageal echocardiography compared to seven by transthoracic technique. By transesophageal echocardiography, mitral regurgitation was paravalvular in 24% compared with 4% by transthoracic technique. Left atrial spontaneous contrast was seen in 42% of the patients with a mitral prosthesis detected only by transesophageal echocardiography. Six patients had left atrial or left atrial appendage thrombus and in five patients they were detected only by transesophageal echocardiography. We conclude that transesophageal echocardiography should be a complimentary test to transthoracic studies in patients with suspected prosthetic valve dysfunction or for the follow-up of older tissue valves.     

A Common Color Flow Doppler Finding in the Mitral Regurgitation of Acute Rheumatic Fever

Between October 1986 and May 1991, 19 patients with acute rheumatic fever who were hospitalized in the Department of Pediatrics at Soroka Medical Center underwent echocardiographic color flow Doppler examination. Five patients had an echocardiographic picture of mitral valve prolapse, with or without leaflet thickening, and one had a flail anterior leaflet. Six had mitral valve thickening without prolapse, and seven patients had an echocardiographically normal appearing mitral valve. All 19 patients had a posterolaterally directed jet of mitral regurgitation demonstrated on color flow Doppler. All patients had echocardiographically normal aortic valves. However, mild aortic regurgitation was noted in eight of them. The posterolateral jet of mitral insufficiency in acute rheumatic fever may be the most common echo-Doppler finding in this condition. (ECHOCARDIOGRAPHY, Volume 8, November 1991)
Summary and Conclusions     

Transesophageal color Doppler echocardiography of the normal St. Jude Medical mitral valve prosthesis

Transesophageal color flow Doppler findings are reported in 36 patients with a St. Jude Medical mechanical mitral valve prosthesis who had no auscultatory evidence for prosthetic valve dysfunction. Multiple jets consistent with mitral regurgitation originating from the central and lateral portion of the prosthesis were found in all patients. Maximum jet length ranged from 11 to 51 mm (mean 21 +/- 9 mm). Maximum jet area ranged from 0.2 to 4.1 cm3 (mean 1.2 +/- 0.9 cm2). The color M-mode Doppler interrogation showed two distinct components of the regurgitant jet: brief early systolic flow consistent with valve closure followed by holosystolic regurgitant flow consistent with transvalvular leakage. Four patients (11%) had a maximum regurgitant jet length exceeding 30 mm and absence of early systolic closure regurgitant flow by M-mode color imaging, suggesting clinically silent paravalvular leakage. Two pin-sized paravalvular suture line defects were confirmed in one patient at cardiac transplantation. We conclude that transesophageal echocardiography is a highly sensitive method for detection of mitral regurgitation in the St. Jude Medical mitral prosthesis. Clinically silent paravalvular leakage should be suspected if the maximum jet length exceeds 30 mm and color M-mode interrogation fails to demonstrate an early systolic closure regurgitant flow component.     

经胸与经食管超声心动图对心脏人工瓣膜的对比研究

４７例心脏人工机械瓣膜置换术后的病人，经胸超声心动图（ＴＴＥ）和经食管超声心动图（ＴＥＥ）对比研究显示，低估二尖瓣置换后人工瓣膜返流程度的分级和返流的发生率；主动脉瓣和二尖瓣置换的病人，ＴＴＥ探查人工二尖瓣返流的效果硬差。ＴＥＥ能较容易地探查人工二尖瓣瓣周漏。揭示对人工二尖瓣的评价，ＴＥＥ比ＴＴＥ能提供更多更可靠的信息，毫无疑问这是由于ＴＴＥ检查时人工瓣膜材料的声衰减和血流掩盖的影响，但我们的经验揭示，在评价主动脉瓣置换人工瓣膜时，ＴＥＥ并不优于ＴＴＥ。     

Comparison of transthoracic and transesophageal color Doppler flow imaging in patients with mechanical prostheses in the mitral valve position

This study determined the relative value of transthoracic and transesophageal color Doppler flow imaging to systolic flow patterns in the left atrium in different types of mechanical prostheses in the mitral valve. Thirty-nine patients were investigated. Based on clinical findings, 36 of 39 patients had normal prosthetic valve function. Seventeen patients were interrogated within a few days after surgery. Systolic regurgitant jets in the left atrium were absent in all patients by both transthoracic pulsed and color Doppler flow imaging. Using transthoracic continuous wave Doppler, however, jets were demonstrated in 8 of 39 patients (21%). Transesophageal color Doppler flow imaging demonstrated systolic regurgitant jets originating from the prosthesis in all patients. Tilting disc valves showed jets during the entire systole (closure and leakage backflow). Each type of prosthesis generated a specific jet pattern. Pathologic regurgitant jets were crescent-shaped, more extensive and turbulent than jets caused by normal closure and leakage backflow. Thus, transthoracic color Doppler flow imaging is not sensitive for detecting regurgitant jets in mechanical prostheses in the mitral valve. All mechanical prostheses show a specific jet pattern, which should be helpful when transesophageal echocardiography is used to identify pathologic backflow.     

Regurgitant jet size by transesophageal compared with transthoracic Doppler color flow imaging

Combined echocardiography and Doppler color flow mapping from transthoracic imaging windows has become the standard method for the noninvasive assessment of valvular regurgitation. This study compared regurgitant jet areas by Doppler color flow imaging derived from the newer transesophageal approach with measurements obtained from conventional transthoracic apical views. Maximal regurgitant jet area determinations and an overall visual estimate of lesion severity were obtained from 42 patients who underwent color flow examination by both techniques. Seventy-three regurgitant lesions were visualized by transesophageal flow imaging: 34 mitral, 22 aortic, and 17 tricuspid jets. Transthoracic studies in the same patients revealed fewer regurgitant lesions for each valve; 20 mitral, 16 aortic, and 12 tricuspid (p = 0.0009). A comparison of maximal jet areas determined by transesophageal and transthoracic studies showed a good overall correlation (r = 0.85, SEE = 2.8 cm2) and a systematic overestimation by the transesophageal technique (TEE = 0.96 TTX + 2.7). For the subgroup with mitral insufficiency, valve lesions visualized by both techniques were larger by the transesophageal approach (n = 18, 6.0 versus 3.6 cm2, p = 0.008). Semiquantitative visual grading of individual valve lesions by two independent observers revealed a higher grade of regurgitation with more jets classified as mild (38 versus 25), moderate (18 versus 13), and severe (17 versus 10) by esophageal imaging than by transthoracic imaging. Thus, transesophageal color flow mapping techniques yield a higher prevalence of valvular regurgitation than do transthoracic techniques in the same patients. Jet area and the overall estimate of regurgitant lesion severity were also greater by transesophageal color Doppler imaging compared with standard transthoracic imaging.(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.     

A quantitative comparison of transesophageal and epicardial color Doppler echocardiography in the intraoperative assessment of mitral regurgitation

Epicardial and transesophageal color Doppler echocardiography are both widely used for the intraoperative assessment of mitral regurgitation (MR); however, it has not been established whether grading of regurgitation is comparable when evaluated by these 2 techniques. MR jet size was quantitatively compared in 29 hemodynamically and temporally matched open-chest epicardial and transesophageal color Doppler echocardiography studies from 22 patients (18 with native and 4 with porcine mitral valves) scheduled to undergo mitral valve repair or replacement. Jet area, jet length and left atrial area were analyzed. Comparison of jet area measurements as assessed by epicardial and transesophageal color flow mapping revealed an excellent correlation between the techniques (r = 0.95, p less than 0.001). Epicardial and transesophageal jet length measurements were also similar (r = 0.77, p less than 0.001). Left atrial area could not be measured in 18 transesophageal studies (62%) due to foreshortening, and in 5 epicardial studies (17%) due to poor image resolution. Acoustic interference with left atrial and color flow mapping signals was noted in all patients with mitral valve prostheses when imaged by epicardial echocardiography, but this did not occur with transesophageal imaging. Thus, in patients undergoing valve repair or replacement, transesophageal and epicardial color flow mapping provide similar quantitative assessment of MR jet size. Jet area to left atrial area ratios have limited applicability in transesophageal color flow mapping, due to foreshortening of the left atrial borders in transesophageal views. Transesophageal color flow mapping may be especially useful in assessing dysfunctional mitral prostheses due to the lack of left atrial acoustic interference.     

Thrombosis of atrioventricular prosthesis. Contribution of transesophageal echocardiography]

The aim of this study was to assess the diagnostic value of transesophageal echocardiography for the detection of thrombosis of a mechanical mitral or tricuspid valve prosthesis. Twelve patients (mean age 54 +/- 12 years) out of a series of 39 patients operated between April 1988 and June 1989 for prosthetic valve dysfunction had valve thrombosis at operation (11 mitral and 1 tricuspid valve prosthesis). Transesophageal echocardiography was routinely performed preoperatively in addition to transthoracic Doppler echocardiography to search for an abdominal mass on the prosthetic valves. The largest diameter of the diastolic jet at the level of the prosthetic valve annulus was measured using transesophageal color flow Doppler in the 8 Starr-Edwards mitral valve prostheses and compared with 5 control valves. The results of transthoracic Doppler echocardiography and transesophageal echocardiography were compared with the operative findings. The specificity of transthoracic echocardiography for the positive diagnosis of prosthetic valve thrombosis was 18%. A thrombosis could be suspected in 10 of the 12 cases by transthoracic echocardiography giving a sensitivity of 83%. Eleven of the 12 abnormal masses on the prostheses were visualised by transesophageal echocardiography, a sensitivity of 91%. Detection of the masses on the arterial side was possible in all cases (10/10) but 5 of the 6 extensions of the thrombus into the ventricle could not be visualised. The diameter of the transprosthetic jet was less than 12 mm in 7 of the 8 thrombosed valves compared with greater than 15 mm in the 5 normal control prostheses.(ABSTRACT TRUNCATED AT 250 WORDS)     

Doppler echocardiographic evaluation of Hancock and Bj?rk-Shiley prosthetic values

Doppler echocardiographic characteristics of normally functioning Hancock and Bj?rk-Shiley prostheses in the mitral and aortic positions were studied in 50 patients whose valvular function was considered normal by clinical evaluation. Doppler studies were also performed in 46 patients with suspected malfunction of Hancock and Bj?rk-Shiley valves and who subsequently underwent cardiac catheterization. Mean gradients were estimated for both mitral and aortic valve prostheses and valve area was calculated for the mitral prostheses. Doppler prosthetic mitral valve gradient and valve area showed good correlation with values obtained with cardiac catheterization (r = 0.93 and 0.97, respectively) for both types of prosthetic valves. The correlation coefficient (r = 0.93) for mean prosthetic aortic valve gradient was also good, although Doppler echocardiography overestimated the mean gradient at lower degrees of obstruction. Regurgitation of Hancock and Bj?rk-Shiley prostheses in the mitral and aortic positions was correctly diagnosed. These results suggest that Doppler echocardiography is a reliable method for the characterization of normal and abnormal prosthetic valve function.     

Doppler hemodynamic evaluation of prosthetic (Starr-Edwards and Bj?rk-Shiley) and bioprosthetic (Hancock and Carpentier-Edwards) cardiac valves

One hundred thirty-four patients with prosthetic or bioprosthetic heart valves were investigated with Doppler echocardiography to determine normal values for commonly used prosthetic valves and to test the specificity of abnormal Doppler findings. In 70 patients the aortic valves had been replaced and in 64 the mitral valves had been replaced. Gradients across prostheses in the aortic position were calculated from maximal velocity. Peak calculated aortic transvalvular gradients in normal subjects were 22 +/- 10 mm Hg in 33 Bj?rk-Shiley valves, 23 +/- 10 mm Hg in 27 porcine valves and 29 +/- 13 mm Hg in 6 Starr-Edwards valves. Mild aortic regurgitation was seen in 42% of Bj?rk-Shiley valves, 26% of porcine valves and 2 of 6 Starr-Edwards valves. Mitral valve orifice was calculated by the pressure half-time method. In clinically normal patients with mitral valve prostheses, the effective mitral valve orifice was 2.5 +/- 0.8 cm2 in 35 Bj?rk-Shiley valves, 2.1 +/- 0.7 cm2 in 17 porcine valves, and 2.0 +/- 0.3 cm2 in 10 Starr-Edwards valves. Mitral regurgitation was found in 11% of Bj?rk-Shiley valves, 19% of porcine valves and 30% of Starr-Edwards valves. Repeat studies at 2 weeks to 14 months revealed no difference in 8 aortic and 14 mitral prostheses. Seven aortic and 4 mitral valves functioned abnormally as determined by Doppler, and the abnormal function was confirmed in each at surgery or at cardiac catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anatomo-functional study of non-rheumatic mitral insufficiency with transesophageal echocardiography]

Reconstruction surgery of the mitral valve has become an alternative to mitral replacement in patients with pure mitral regurgitation. Preoperative assessment of the anatomic and functional aspects of the valvular lesion is of the utmost importance in conservative surgery. Transesophageal echocardiography is a new approach to investigating the mitral valve, and our study was undertaken with the purpose of determining its importance in the exploration of mitral regurgitation of non-rheumatic origin. Subjects included were twenty patients with pure and isolated mitral regurgitation (MR): 14 males and 6 females with an average age of 47 +/- 13 years. All the patients underwent a first transesophageal 2D and color Doppler echocardiographic examination, and 5 of them underwent a second one during cardiovascular surgery. Mitral anulus diameter, mitral valve cordae tendinae status, valvular leaflet length and coaptation were examined and color Doppler regurgitation jet area was measured. Mitral anulus diameter was 40.2 +/- 8.06 mm (diastolic) and 41.9 +/- 8.53 mm (systolic) and was above the values considered to be normal. Anterior leaflet length was 30.8 +/- 3.12 mm and posterior leaflet length was 22.9 +/- 4.74 mm; regurgitation jet area was between 1.2 cm2 and 13.52 cm2 with an average of 5.44 cm2. In the group with MR of mixomatous origin, systolic anulus diameter showed a linear correlation with regurgitation jet area (r = 0.79). In the 6 patients who underwent cardiac catheterization, angiographic semiquantitative evaluation of the MR confirmed that based on color Doppler jet area. In all twenty patients transesophageal echocardiography enabled us to identify the mechanism responsible for mitral insufficiency.(ABSTRACT TRUNCATED AT 250 WORDS)     

Doppler echocardiography assessment of prosthetic heart valves

Transthoracic Doppler echocardiography is an accurate noninvasive method for the evaluation of prosthetic valve function. The flow characteristics and pressure gradients of normally functioning mechanical and bioprosthetic valves have been, in general established. Normal functioning mitral valve prostheses have a valve area > 1.8 cm² with the St. Jude valve having the largest effective valve area and normally functioning aortic prosthetic valves have a peak instantaneous gradient of < 45 mmHg, with the Starr-Edwards valves (Starr-Edwards, Irvine CA) showing the highest gradients. The incidence of minimal or mild regurgitation is approximately 15% to 30% in the mitral position and 25% to 50% in the aortic position, with the higher incidence of regurgitation seen with mechanical compared to bioprosthetic valves. Transthoracic Doppler echocardiography can accurately detect patients with prosthetic valvular stenosis. The presence of prosthetic aortic regurgitation can also generally be accurately assessed, except in the presence of both prosthetic aortic and mitral valves. Assessment of prosthetic mitral regurgitation remains limited due to significant attenuation of the ultrasound beam by the prosthesis and the frequent underestimation of severity of regurgitation. Other limitations of transthoracic studies include assessment of leaflet morphology, detection of vegetations and valve abscesses, and differentiation between valvular and paravalvular regurgitation.     

Flexible aortic valve prostheses: long-term functional results with porcine bioprostheses without mechanical commissure stent and aortic homografts

The long-term performance of two different types of flexible aortic prostheses was evaluated in 10 patients who received a stentless porcine prosthetic valve (group A) and in 18 patients who underwent aortic valve replacement with an aortic homograft (group B). In group A early postoperative angiography (5-16 days post surgery) revealed a mean gradient across the aortic prosthesis of 8 +/- 6 mmHg. Late postoperative Doppler echocardiography (3.2 +/- 0.9 years post surgery) suggested a mean gradient of 6 +/- 3 mmHg with a Doppler derived valve orifice area of 1.8 +/- 0.6 cm2. Color Doppler visualized mild prosthesis regurgitation in two of the 10 patients and two-dimensional imaging showed no significant leaflet calcification. In group B late postoperative Doppler echography (5.2 +/- 1.6 years post surgery) suggested a mean gradient of 11 +/- 14 mmHg with a mean graft orifice area of 1.8 +/- 0.5 cm2. Color Doppler revealed prosthesis regurgitation in 15 patients (severe 1, moderate 2, mild 12) and two-dimensional imaging visualized significant prosthesis leaflet calcification in two patients. The good hemodynamic function of a stentless porcine bioprosthesis which seems to be preserved for at least several years indicates that the use of the flexible aortic xenograft is worthwhile pursuing. The long-term performance of an aortic homograft is relatively poor and may be due to unsolved problems with regard to sterilizing and storing the valves.     

Assessment of severity of mitral regurgitation by measuring regurgitant jet width at its origin with transesophageal Doppler color flow imaging.

BACKGROUND. The ability of transesophageal color Doppler echocardiography to provide high-resolution images of both cardiac structure and blood flow in real time is advantageous for many clinical purposes. This study was performed to determine the utility of the regurgitant jet width at its origin measured by transesophageal Doppler color flow imaging in the assessment of severity of mitral regurgitation. METHODS AND RESULTS. Sixty-three consecutive patients with mitral regurgitation underwent transesophageal color Doppler examination, and the diameter of regurgitant jet at its origin was measured. Both right and left cardiac catheterizations were performed within 24 hours of Doppler studies, and angiographic grading of mitral regurgitation and regurgitant stroke volume were evaluated. There was a close relation between the jet diameter at its origin measured by transesophageal Doppler color flow imaging and the angiographic grade of mitral regurgitation (r = 0.86, p less than 0.001). A jet diameter of 5.5 mm or more identified severe mitral regurgitation (grade III or IV) with a sensitivity of 92%, specificity of 92%, and positive and negative predictive values of 88% and 95%, respectively. In 31 patients with isolated mitral regurgitation, the jet diameter correlated well with the regurgitant stroke volume determined by a combined hemodynamic-angiographic method (r = 0.85, p less than 0.001). A jet diameter of 5.5 mm or more identified a regurgitant stroke volume of 60 ml or more with a sensitivity of 88%, specificity of 93%, and positive and negative predictive values of 94% and 87%, respectively. CONCLUSIONS. The regurgitant jet width at its origin measured by transesophageal Doppler color flow imaging provides a simple and useful method of measuring the severity of mitral regurgitation, and it may allow differentiation between mild and severe mitral regurgitation.