Intraoperative Epicardial Echocardiography Research Articles

Intraoperative Epicardial Echocardiography Locates the Origin of a Coronary -Pulmonary Artery Fistula.

The clinical usefulness of intraoperative epicardial echocardiography in a patient with post-infarction angina complicated by a coronary-pulmonary artery fistula (CPAF) with aneurysmal change was reported. Epicardial echocardiography clearly showed feeding arteries to the fistula in the myocardium, which was not revealed by visual inspection, palpation, or transesophageal echocardiography. The patient was received off-pump coronary artery bypass grafting concomitant with aneurysmectomy. The feeding arteries were dissected easily using an ultrasonic scalpel and successfully ligated. The flow in the aneurysm disappeared immediately and aneurysmectomy was performed without bleeding. Intraoperative epicardial echocardiography was useful method during off-pump resection of CPAF.

Epicardial echocardiography: diagnostic utility for evaluating aortic valve disease during coronary surgery

Intraoperative epicardial echocardiography is commonly used to evaluate the ascending aorta for atheromatous disease before cannulation and cross clamping. In addition, it may serve as a cardiac imaging technique in patients where placement of a transesophageal echocardiography (TEE) probe is contraindicated, probe advancement is difficult, or a TEE probe is not available. We report a patient who was taken to the OR for coronary artery bypass grafting. Intraoperative TEE was planned to evaluate aortic valve function. However, attempts to place a TEE probe were abandoned due to high resistance on probe insertion. Epicardial echocardiography revealed previously undiagnosed aortic valve disease resulting in replacement of this valve.

Intraoperative transesophageal echocardiography for pediatric patients with congenital heart disease.

Intraoperative transesophageal echocardiography for pediatric patients with congenital heart disease.

A videodensitometric study of transmural heterogeneity of cyclic echo amplitude variation in human myocardium

The aims of this study were: (1) to assess whether variations in cyclic echo amplitude might be detected across the human myocardium by videodensitometric analysis of images obtained with epicardial echocardiography; and (2) to explore the possible relation between cyclic gray level variation and left ventricular (LV) hypertrophy and function. Experimental studies show that transmural differences in contractile performance across the normal myocardium are paralleled by differences in the cyclic (diastolic-to-systolic) variation of myocardial echo amplitude. Thirty-three patients (aged 60 ± 11 years) undergoing cardiac surgery were studied by intraoperative epicardial echocardiography. LV mass index was normal (<110 g/m 2 in women, <131 g/m 2 in men) in 10 patients and increased in 22. Two-dimensional echocardiographic images were obtained with a 5 MHz transducer and digitized off-line. Videodensitometric analysis was performed at end-diastole and endsystole with regions of interest across the septal and posterior wall. The cyclic variation was more pronounced in the left than in the right septal subendocardium (31% ± 14% vs 16% ± 14%, p < 0.01) and higher in the subendocardial than in the subepicardial layer of the posterior wall (30% ± 21% vs 23 ± 18%, p < 0.01). Cyclic variation of the left septal subendocardium was higher in 11 patients with nonhypertrophic ventricles than in 22 with hypertrophic left ventricles (42% ± 15% vs 27% ± 12%; p < 0.01). The percent cyclic variation of the left septal subendocardium appeared to be much more tightly related to percent systolic thickening in patients with eccentric LV hypertrophy (r = 0.80 p < 0.01) than in patients with concentric LV hypertrophy (r = 0.27, p = 0.9) or normal LV mass (r = 0.43, p = 0.2). A cyclic gray level variation can be consistently detected in different human myocardial regions and layers. It is more obvious in the subendocardial than in the subepicardial layer, and in nonhypertrophic than hypertrophie ventricles. The cyclic subendocardial variation is tightly related to regional systolic thickening in patients with eccentric LV hypertrophy.

Intraoperative epicardial echocardiography in assessing pulmonary artery banding procedures

Accurate perioperative assessment of the adequacy of pulmonary artery banding has hitherto relied on oximetry and direct pressure measurements. We report the use of epicardial Doppler echocardiography for assessing banding procedures. Six consecutive infants (3 male, 3 female; median age, 17 days) who underwent pulmonary artery banding for complex defects were studied by intraoperative epicardial Doppler echocardiography. Excellent visualization of the relation of the band to the pulmonary valve and branch arteries was obtained, enabling or confirming optimal positioning. Doppler echocardiographic estimation of the pressure drop across the band was possible in each patient and resulted in further tightening of the band in 2 patients (33%) with satisfactory increases in transband pressure gradients. Intraoperative echocardiographic estimates of the transband gradients (median, 57 mm Hg; range, 52 to 71 mm Hg; mean +/- standard deviation, 59 +/- 7 mm Hg) correlated well with those obtained at subsequent transthoracic echocardiography (median gradient, 66 mm Hg; range, 52 to 67 mm Hg; mean +/- standard deviation, 63 +/- 6 mm Hg). Epicardial echocardiography is a valuable adjunct to direct pressure and saturation measurements for adjustment of final band size and aids in confirming accurate band placement.

Repair of complete atrioventricular canal defects: Results with the two-patch technique

Between 1983 and 1994, 115 infants and children underwent repair of a complete atrioventricular canal defect with the two-patch technique and routine mitral valve "cleft" closure. A retrospective review of these 115 patients was performed. Age at the time of repair ranged from 1 month to 108 months (mean age, 14.2 +/- 16.5 months; median age, 8 months). Preoperative cardiac catheterization in 113 patients revealed a mean pulmonary to systemic flow ratio of 3.37 +/- 1.8, a mean pulmonary artery systolic pressure of 71.1 +/- 15.7 mm Hg, and a mean pulmonary vascular resistance of 4.9 +/- 3.3 units. Associated anomalies included Down's syndrome (99 patients), patent ductus arteriosus (47), and coarctation of the aorta (4). Rastelli classification was A (76 patients), B (10), C (24), and unknown (5). Twenty-four patients had intraoperative epicardial or transesophageal echocardiography. Although there was a trend toward increasing mean preoperative pulmonary vascular resistance with age from 2.1 +/- 0.9 units (0 to 3 months) to 4.0 +/- 2.6 units (4 to 6 months) to 5.7 +/- 3.0 units (7 to 12 months), the mean pulmonary vascular resistance of each age group was not significantly different from that of the main group. The operative survival rate was 94% (seven early deaths) and the overall survival rate, 91% (three late deaths). Intraoperative echocardiography altered the surgical therapy for 1 patient. No patient has required reoperation for a residual ventricular septal defect. Four patients (3.5%) had heart block requiring permanent pacemakers. Eight patients (7%) required reoperation for mitral insufficiency; 6 of whom had successful repair of a residual cleft. For infants with complete atrioventricular canal defect, repair using the two-patch technique with routine mitral valve cleft closure at 4 to 6 months of age results in a low operative mortality, a low incidence of permanent heart block, and a low reoperation rate for mitral insufficiency.

Intraoperative Evaluation of Valvular Function Using Transesophageal and Epicardial Echocardiography

Objectives and Background. Intraoperative transesophageal echocardiography (TEE) and epicardial echocardiography (ECE) offer the opportunity to assess valvular function before and after cardiopulmonary bypass. Valve reconstruction offers many advantages over prosthetic valve replacement. The purpose of this study was to assess the utility of TEE and ECE during the surgical treatment of mitral, aortic, and tricuspid valve diseases. Methods. Intraoperative echocardiography was performed in 50 patients undergoing surgery for valvular heart disease. In 21 recent patients, concurrent TEE with Doppler color flow mapping was performed. The severity of mitral stenosis (MS) was assessed by the intraoperative echocardiographic mitral valve area (MVA) and morphologic findings of the mitral apparatus. The severity of mitral regurgitation (MR) was visually graded on a semiquantitative scale of 0-4+ according to the ratio of the maximal regurgitant jet area to the left atrial area (JA/LAA) indicated by transesophageal and epicardial Doppler color flow mapping. The severity of aortic regurgitation (AR) was similarly graded on a scale of 0-4+ according to the ratio of the maximal regurgitant jet area to the left ventricular area (JA/LVA) in end diastole. The severity of tricuspid regurgitation (TR) was similarly graded on a scale of 0-4+ according to the ratio of the maximal regurgitant jet area to the right atrial area (JA/RAA). These criteria for the severity of valvular regurgitation were compared with conventional nonsimultaneous angiographic criteria and operative criteria according to fluid injection into the flaccid ventricles. Tricuspid annulus diameter during systole was measured before and after tricuspid annuloplasty. Results. There was a good correlation (r = 0.78, P &lt; 0.001) between intraoperative two-dimensional echocardiographic MVA and operative MVA by direct measurement. Epicardial two-dimensional MVA and transthoracic MVA measured by mitral pressure half time method were similar (r = 0.88, P &lt; 0.005). Mitral commissurotomy was performed in 4 (27%) of 15 patients with MS. Comparison of mitral JA/LAA measurements as assessed by epicardial and transesophageal color flow mapping revealed an excellent correlation between the techniques (r = 0.94, P &lt; 0.001). Intraoperative TEE and ECE assessment of the severity of MR showed good agreement with preoperative angiographic gradings and with operative gradings. Mitral valve repair was performed in 10 (48%) of 21 patients with MR. Postrepair intraoperative Doppler studies showed satisfactory surgical results in all. No significant residual MR (grade &gt; 2+) was identified in this series. Comparison of aortic JA/LVA measurements as assessed by epicardial and transesophageal color flow mapping showed an excellent correlation between the techniques (r = 0.96, P &lt; 0.001). Intraoperative echocardiographic assessment of the severity of AR showed good correlation with preoperative angiographic assessment. Aortic valve repair was performed in 1 (11%) of 9 patients with AR. There was a good correlation (r = 0.77, P &lt; 0.005) between tricuspid JA/RAA ratios as assessed by epicardial color flow mapping and operative gradings for TR. Tricuspid annulus diameter during systole measured by epicardial technique was significantly (P &lt; 0.001) decreased after tricuspid annuloplasty. Conclusions. Both intraoperative TEE and ECE are useful for the evaluation of valvular function in the mitral, aortic, and tricuspid positions. Doppler color flow mapping is a reliable method of assessing valve regurgitation. Combined intraoperative use of transesophageal and epicardial techniques is recommended.

New surgical method of chordal replacement for mitral valve incompetence with echocardiographic guidance: An experimental study

Chordal replacement with expanded polytetrafluoroethylene suture has become a procedure of choice for repairing anterior leaflet prolapse among certain surgeons. However, most surgeons believe that the chordal replacement is too complicated and not reproducible. This report introduces a new method of chordal replacement using intraoperative epicardial and transesophageal echocardiography. Three dogs underwent the following procedures. One major marginal chorda of an anterior mitral leaflet was resected during cardiopulmonary bypass. A specially designed 3-0 polytetrafluoroethylene suture, having straight needles, was attached to the anterior leaflet by a mattress suture. Then the needles were brought from the root of the anterior papillary muscle to the outside of the left ventricle. After the bypass flow was reduced, both ends of the polytetrafluoroethylene suture were pulled under echocardiographic guidance until valve competence was achieved. At that point, the suture was temporarily tied. When cardiopulmonary bypass was discontinued, competence was again confirmed and the suture was tied permanently. When the procedures were completed, echocardiography showed trivial regurgitation and good pliability of the anterior leaflets in all animals. Left atrial pressures were sufficiently decreased. It appears that this new technique is reproducible for all surgeons because the optimal length of polytetrafluoroethylene chordae is determined with the valve functioning. (J THORAC CARDIOVASC SURG 1994;108:719-26)

Intraoperative epicardial echocardiography with a miniature high-frequency transducer: imaging techniques and scanning planes.

Intraoperative Doppler echocardiography has the potential to provide anatomic and functional information but is hindered by the large size of standard transducers. We describe new scanning planes accessible through the application of a new 5 MHz miniature transducer with imaging, Doppler, and color-flow capability. Epicardial echocardiography was performed in 15 adults undergoing elective coronary artery bypass grafting. Standard parasternal equivalent, subcostal equivalent, aortopulmonary sulcus and aortosuperior vena caval views were obtained. Previously unobtainable apical four-chamber, five-chamber, and long-axis views were possible by positioning the transducer at the apex. The transducer has a broad bandwidth, allowing high-quality imaging at different depths and could be maneuvered laterally, posteriorly, and over the aorta and pulmonary arteries to provide off-axis views. The proximal-mid coronary arteries were imaged on the beating heart with a standoff medium. Transducer miniaturization should expand the role of epicardial ultrasonography in the surgical management of heart disorders.

Intraoperative epicardial echocardiography during repair of tetralogy of Fallot.

Intraoperative assessment of surgical results in patients with congenital heart defects has been limited in the past to oximetry or green dye curves to evaluate residual shunts and pressure measurements to evaluate residual obstruction to flow. Echocardiography with color flow Doppler imaging has emerged as a very sensitive technique to evaluate congenital heart repair. • A large prospective study performed in our institution to test the ability of epicardial echocardiography to assess the surgical repair of congenital heart disease has been previously reported. 5 Likewise, the learning process necessary for a surgical team to acquire adequate skills in using this technology has also been the subject of previous work. 6 Other investigations have also reported on the use of intraoperative echocardiography as a guide to the repair of congenital heart defects, either from the epicardiaF· or from the transesophageal approach, 3 or both. 3,1z The current study is the first reported series of patients with tetralogy of Fallot (TOF) and related lesions that have been repaired under the guidance of epicardial echocardiography with color flow Doppler imaging. It also provides echocardiographic follow-up for small, residual imperfections in the repair that patients may have at the time they leave the operating room, after successful repair ofTOF.

Combined conventional mechanical and ultrasonic debridement for aortic valvular stenosis

Ultrasound decalcification of aortic valve stenosis was performed in 31 patients. There were 16 men and 15 women with a mean age of 71.03 ± 9.6 years (range, 51 to 89 years). Each had severe calcific aortic stenosis with an aortic valve gradient greater than 40 mm Hg, aortic valve area (AVA) less than 0.6 cm 2, and no serious insufficiency. Feasibility of aortic valve debridement was determined under direct vision. Intraoperative epicardial or transesophageal color Doppler two-dimensional echocardiography was used before and after the aortic valve debridement to evaluate aortic cusp motion and aortic regurgitation. Direct transseptal aortic valve gradient was measured on all patients before and after aortic valve debridement, and the AVA was determined. Aortic valve debridement was performed as the primary procedure in 17 cases and combined with other cardiac procedures in 14 patients. Preoperative aortic valve gradient was reduced from 72.5 ± 22.5 mm Hg (range, 40 to 130 mm Hg) to 15.5 ± 11.9 mm Hg (range, 2 to 50 mm Hg), and the average AVA of 0.41 ± 0.10 cm 2 (range, 0.22 to 0.63 cm 2) was increased to 1.55 ± 0.58 cm 2 (range, 0.65 to 3.50 cm 2) after ultrasound decalcification. There were two early deaths in octogenerian, high-risk patients, and two late deaths (6.45% early and 6.45% late mortality), none of them related to AVD. Postoperative follow-up included clinical evaluation and color Doppler echocardiography every 6 months. The aortic valve gradient was measured using a continuous-wave Doppler probe, and the AVA was calculated by the simplified continuity equation: AVA = a AOA × v LVOT / v AV . The mean New York Heart Association class was 3.04 ± 0.47 before operation and improved to 2 ± 0.30 after 6 to 12 months ( p = 0.0001) and remained unchanged after 24 to 36 months ( p = 1.000). At 3 years, echocardiography and recatheterization have shown absence of significant restenosis or aortic insufficiency. The average intraoperative AVA after repair (1.57 ± 0.58 cm 2; n = 23) compared well with the calculated AVA at 12 to 18 months (1.72 ± 0.57 cm 2; n = 20) and 24 to 36 months (1.43 ± 0.45 cm 2; n = 14) after operation, based on one-way analysis of variance. One reoperation was necessary for early graft failure and incidental aortic valve replacement was performed. Ultrasound aortic valve debridement with preservation of the native valve appears to be an effective procedure in selected patients. Optimal results may be enhanced by combining standard debulking debridement, low-energy ultrasound, and the use of intraoperative echocardiography and by avoiding a residual AVA of less than 1.5 cm 2.

Hibernating myocardium in patients with coronary artery disease: identification and clinical importance.

The term hibernating myocardium describes a particular outcome of myocardial ischemia in which myocytes show a chronically depressed contractile ability but remain viable. Revascularization of hibernating tissue causes a recovery of mechanical function that correlates with long-term survival. Therefore it is important clinically to distinguish hibernating from infarcted myocardium, since asynergies due to hibernation will improve on reperfusion, whilst those due to infarct will not. One suggested technique to identify hibernating myocardium is to stimulate the myocytes acutely, but briefly, by administration of inotropic agents while monitoring contractile function by echocardiography. We report our experience on the use of low dosages of dobutamine. Myocardial viability was validated by measuring the recovery in contraction of the akinetic areas after coronary artery bypass surgery by means of intraoperative epicardial echocardiography. The test has a sensitivity of 93% and a specificity of 78%. It is useful for identification of viable myocardium and also for quantification of intraoperative risk in individual patients. Limitations of this test are related to the presence of downregulation of beta receptors and to the impossibility of differentiating hibernating from stunned myocardium. Another useful technique of identifying hibernating myocardium is the use of radionuclear markers for viability. In our experience the two most important tests are (1) rest-redistribution imaging of thallium 201 (which has a high sensitivity of 93% but a low specificity of 44%) and (2) 99mTc-Sestamibi imaging, which provides information on both perfusion and function with a single injection. This latter technique allows differentiation between stunning and hibernating on the basis of coronary flow which is preserved in stunning and reduced in hibernation.

Intraoperative Echocardiography for Evaluation of Congenital Heart Defects in Infants and Children

To determine the accuracy, utility, and limitations of intraoperative transesophageal echocardiography (TEE) in infants and children, we performed prebypass and postbypass TEE in 90 children undergoing surgical repair of congenital heart lesions, comparing the results to those obtained using intraoperative epicardial echocardiography and pre- and postoperative precordial echocardiography. Patients ranged in age from 4 days to 21 yr (mean 4.1 yr) and in weight from 3 to 68 kg (mean 15.4 kg). Prebypass, we obtained high-quality, two-dimensional TEE images in 86 patients, with correction of the preoperative precordial diagnosis in 3 and confirmation of the preoperative diagnosis in the rest. Adequate epicardial images were obtained in 78 patients, with confirmation of the preoperative diagnosis in all. Shunt lesions that were well delineated prebypass by both TEE and epicardial imaging included interatrial, interventricular, and atrioventricular septal defect lesions. TEE failed to detect the exact size and location of lesions involving the right ventricular outflow tract, i.e., doubly committed subarterial (supracristal) ventricular septal defects. Regurgitant lesions (n = 30) were identified and their severity evaluated in all patients by both TEE and epicardial imaging. Obstructive lesions (n = 33), excluding those involving the right ventricular outflow tract, were well defined by both echocardiographic approaches. Postbypass, we obtained high-quality, two-dimensional, color and Doppler TEE images in 86 patients and epicardial images in 78 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of intraoperative epicardial echocardiography with color flow imaging during the repair of complete atrioventricular septal defects

The use of intraoperative echocardiography with Doppler color flow imaging has acquired increased popularity for early assessment of efficacy of repair of congenital heart defects soon after discontinuance of cardiopulmonary bypass. This technology has been found useful also for evaluating the anatomy of the lesion prior to repair. Furthermore, with the use of color flow mapping, additional anomalies, such as patent arterial duct or multiple ventricular septal defects, which might have been overlooked during the initial examination, can be easily diagnosed. Moreover, intraoperative echocardiography provides the quickest and most sensitive method for a surgeon to look for residual atrioventricular valves regurgitation and/or residual atrial or ventricular septal defects as well as for depressed ventricular contractility. Previous studies1–4have discussed specifically the applicability of intraoperative color flow imaging during the repair of atrioventricular septal defect with a common atrioventricular orifice using both epicardial and transesophageal methodology. Routine intraoperative echocardiography with Doppler color flow imaging has been used since March 1987 at Duke University Medical Center during repair of congenital heart defects. Our aim was to confirm the preoperative dignosis and to assess the quality of repair soon after discontinuance of cardiopulmonary bypass. Our overall experience now includes 612 patients of whom 239 or 39% were less than one year of age at the time of repair. This indicates our tendency to undertake early correction regardless of the age of patients and of the severity of the lesion.

Intraoperative ultrasonographic identification of coronary artery compression after an arterial switch procedure

A case is reported of a neonate with transposition of the great arteries, undergoing an arterial switch operation, in whom the cause for postbypass cardiac failure was diagnosed by intraoperative epicardial echocardiography. Obvious regional dyskinesia was seen by two-dimensional echocardiography in the posterolateral segments of the left ventricle, supplied by the circumflex coronary artery. After the switch procedure, the reimplanted circumflex artery ran between the aorta and the pulmonary artery. Lifting the pulmonary artery off the circumflex artery resulted in immediate improvement of regional myocardial function, which could be monitored on-line with echocardiography. Thus compression of the circumflex by the pulmonary artery was the cause for cardiac failure. On the basis of the echocardiographic information, immediate and successful surgical revision was performed. Intraoperative epicardial echocardiography has a unique diagnostic potential in the case of cardiac failure after cardiopulmonary bypass.

A new angled transducer for intraoperative epicardial echocardiography.

We tested a new angled transducer developed for intraoperative epicardial echocardiography in 42 patients. This small transducer, 70 x 20 x 15 mm in size, demonstrated superior operability and provided adequate two- or four-chamber imaging from the apical approach, which may lead to high-quality assessment with two-dimensional Doppler flow imaging.

Intraoperative Epicardial Echocardiography: Early Experience With a Newly Developed Small Surgical Transducer

To test the feasibility of performing intraoperative echocardiography with a specially designed epicardial transducer, 20 adult patients were studied. All patients were undergoing coronary bypass surgery and had structurally normal intracardiac anatomy. The surgical transducer has 48 elements and a size at the tip of 10 x 12 x 5 mm. The scan plane has been set at 90 degrees to the cable axis to allow scanning from lateral positions. The terminal 10 cm of the cable has been reinforced to act as a malleable and steerable handle. Good quality images were obtained with the new transducer, and many different imaging planes were identified compared to imaging with the standard transducers. These include the right ventricular apex, the right and left lateral aspects of the heart, the aortic arch, and the pulmonary artery and its branches. The limitation of the probe was the difficulty in obtaining left ventricular apical views because of ventricular arrhythmias sustained when the transducer was placed between the left ventricular apex and the diaphragm. We conclude that this new transducer has a promising future in the application of intraoperative epicardial echocardiography.

Freehand allograft aortic valve replacement and aortic root replacement: Utility of intraoperative echocardiography and Doppler color flow mapping

Seventeen consecutive patients undergoing 20 planned aortic valve replacements with allograft valves at Stanford University Medical Center were studied with intraoperative epicardial echocardiography and Doppler color flow mapping before and after cardiopulmonary bypass. Native aortic valves were replaced in 12 of the 20 patients, and eight patients underwent second aortic valve procedures. In 17 of 20 patients allograft selection was guided by prebypass echocardiographic estimates of annular diameter and/or length of allograft aortic root required. Other prebypass findings included unanticipated severe mitral regurgitation in one patient (which precluded allograft aortic valve replacement), left-to-right shunts in five patients, ascending aortic dissection in one, and aortic root disease necessitating coronary reimplantation or bypass in two. Postbypass echocardiography demonstrated acceptable competency of 18 of 19 allograft valves (mild or no aortic insufficiency). Postbypass echocardiography also documented successful repair of four of five shunts and mild mitral regurgitation in 15 of 19 patients (versus 11 of 19 before bypass). Intraoperative echocardiography-Doppler mapping is a useful adjunct for allograft aortic valve or aortic root replacement; it allows confident selection of appropriate tissue size before aortic cross clamping, which minimizes delay from allograft thawing procedures. It also provides helpful information about the extent of aortic root disease and coronary ostial anatomy before bypass, confirms allograft competency after bypass, and detects accompanying valvular and other hemodynamic lesions before and after allograft valve replacement.

乳幼児開心術症例における術中エコー法の有用性の検討

乳幼児開心術症例における術中エコー法の有用性の検討

Subaortic obstruction: Intraoperative echocardiography as an adjunct to operation

Fourteen patients undergoing operation for subaortic obstruction (membranous obstruction in 11 patients, tunnel obstruction in 2 patients, obstruction due to reduplicated mitral valve tissue in 1 patient) were evaluated by intraoperative epicardial echocardiography. In all 9 patients with “discrete” obstruction who underwent prebypass epicardial echocardiography, the septal and lateral attachments of the lesion were correctly demonstrated. The precise extent of tunnel stenosis was seen in both patients. The lateral attachment of the membrane in 4 patients and multiple extensions in another 2 were identified by the epicardial study (having been missed on precordial echocardiography). The discrete membrane was enucleated in 10 of the 11 patients and was partially resected in 1. One tunnel obstruction was completely relieved; the other was partially relieved. Reduplicated mitral valve tissue in the remaining patient was completely resected. Epicardial imaging after bypass showed remnants of the membrane in 2 patients. Intraoperative Doppler echocardiography and color flow imaging confirmed the absence of clinically significant residual gradients (less than 20 mm Hg) in all but 1 patient with tunnel obstruction. Epicardial imaging provided excellent morphological information about obstructive lesions of the left ventricular outflow tract and enabled immediate assessment of surgical repair.