Study Participants

We consecutively enrolled all patients in our congenital program with planned surgical repair of an AV valve between January 2005 and December 2007 at the Stollery Children’s Hospital at the University of Alberta. Our program includes both children and adults with congenital heart disease. This retrospective study was approved by the Human Research Ethics Board at the University of Alberta.

Study Protocol

All patients underwent complete 2D TTE and RT3DE 1 to 30 days prior to AV valve surgery. Of note, both studies were performed during the same echocardiographic examination. Prior to surgery, all but 2 patients underwent complete 2D transesophageal echocardiographic examinations. Two patients were considered too small (2.0 and 2.2 kg) for 2D TEE.

Two-Dimensional TTE

Complete 2D transthoracic echocardiographic and color Doppler studies were performed in all patients using a Philips iE33 (Philips Medical Systems, Bothell, WA) with an S5-1, S8-3, or S12-4 probe. Two-dimensional TTE included all standard parasternal and apical views, with an additional posterior to anterior sweep in the 4-chamber view during both image and color Doppler acquisition. The 2D transthoracic studies were performed by one of our experienced sonographers, using our standard protocol for AV valve evaluation.

RT3DE

RT3DE was performed at the end of the 2D transthoracic echocardiographic examination, using either a matrix X3-1 or X7-2 transthoracic probe. Of note, at the time of the study, we did not have the matrix transesophageal echocardiographic probe. Full-volume data sets were acquired by either J.F.S. or K.T., depending on who was available. The protocol included full-volume analysis using the high–frame rate mode, with the narrowest sector size to provide an image with optimal valve detail. For all left AV valve patients, a data set was acquired from both the apical and parasternal long-axis view. In those with TV, pathologic images were obtained from an apical or slightly medial 4-chamber view. The acquisition was performed during a breath hold at end-expiration in patients aged > 3 years. For children aged < 3 years, the study was performed during quiet respiration after the administration of oral sedation with chloral hydrate, to minimize stitch artifacts. All real-time 3D data sets were obtained both in grayscale and with color Doppler imaging. The raw data sets were initially stored on a DVD and later transferred back to the iE33 for reconstruction. In all cases, later reconstruction of the valve (volume-rendering imaging) allowed a complete visualization of all segments of the left AV or TV.

Two-Dimensional TEE

Two-dimensional TEE was performed just prior to the operation, after the induction of anesthesia and endotracheal intubation. Probe size was dependent on the patient’s weight (S7-3t or SS7-2 OmniPlane probe for the Philips iE33). Two-dimensional transesophageal echocardiographic and color Doppler evaluation included a 4-chamber view with a sweep from posterior to anterior, as well as sweep from 0° to 120° to evaluate all aspects of the leaflets.

Surgical Evaluation

In all cases, a detailed surgical report was available for review. We had initially attempted to record all of the procedures on digital video, being successful in 40, but in 8 patients for technical reasons the camera was not available. A diagram ( Figure 1 ) was provided to the surgeon to complete after the operation. The surgeons used their reports as well as the video recordings in those for which they were available.

Definition of valve leaflets used in this study. All images are viewed from the atrium and are as seen by the surgeon. (Top) Normal MV with an anterior and a mural leaflet. (Middle) Left AV valve seen in an AV septal defect, with a superior and an inferior bridging leaflet and a mural leaflet. The space between the superior and inferior bridging leaflets is the cleft. (Bottom) Normal TV with anterior, posterior, and septal leaflets.

Reconstruction of 3D Data Sets

En face views of the left AV or TV from the left or right atrium and left or right ventricle were reconstructed to determine the precise anatomy of the valve leaflets and the mechanisms and sites of regurgitation. The mechanisms and sites of regurgitation were determined by obtaining an en face view of the valve with superimposition of the vena contracta(s). All 2D transthoracic and transesophageal images were analyzed by two experts in 2D echocardiography (J.D.D. for the left AV, M.R. for the TV) blinded to the surgical or real-time 3D findings. The 2D transthoracic and transesophageal images were reviewed in unison, because this represents the current practice prior to AV valve surgery. We did not design the study to compare 2D TTE and 2D TEE with each other. Three-dimensional data sets were reconstructed and analyzed by two experienced observers (J.F.S. for the left AV, K.T. for the TV). In 30 cases, 3D reconstruction was performed on the iE33 ultrasound machine using imported stored data from the original DVD ≥3 months after the date of RT3DE to minimize the influence of prior 2D and surgical findings. For the remaining 18 cases, 3D reconstruction was performed on the iE33 machine by a reviewer who was unaware of the 2D findings prior to the surgery. The quality of the 3D reconstructed images, on the basis of the clarity of the AV valve anatomy and the presence or absence of artifacts throughout the cardiac cycle, was rated as adequate or poor.

Definition of Terms Used for Analysis

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  Structural abnormality of the leaflet: This was defined as a leaflet with thickening, tears, or deformation (other than prolapse).

  
  
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  Leaflet definitions: Figure 1 demonstrates the accepted leaflet nomenclature used to describe the left-sided AV valve component in an AV septal defect, as well as for a normal MV and TV. In an AV septal defect, there are 3 left-sided leaflets: the superior and inferior bridging leaflets and a smaller mural leaflet. Of note, the mural leaflet has a similar embryologic derivation as the posterior leaflet of the MV; therefore, for simplicity, we refer both as the mural leaflet. For the TV, there is an anterior, a posterior, and a septal leaflet.

  
  
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  Commissural abnormality: This was defined by the line of coaptation between the leaflets, excluding the so-called cleft between the superior and inferior bridging leaflet, which was dealt with separately. The commissure was considered abnormal if it appeared to be irregular in nature or deficient. For those with AV septal defects, there was a superior bridging-mural leaflet or inferior bridging-mural leaflet commissure, while for those with normal MVs, it was the commissure at A1/P1 or A3/P3 (terms routinely used to arbitrarily describe the leaflets of the MV). For those with TVs, it was between the anterior-septal, anterior-posterior, or posterior-septal leaflets.

  
  
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  Poor coaptation: This was defined as any area of the left AV valve or TV at which there was an obvious gap between the leaflet edges that could be observed during systole.

  
  
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  Prolapse: This was defined as leaflet tissue that extended past the annulus in systole. Using 2D TTE and 2D TEE, this was documented for the left AV from the long-axis view and for the TV from the 4-chamber image. With RT3DE, it was possible to use multiple imaging views for both the left AV and TV.

  
  
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  Cleft (for the left AV in patients with AV septal defects): This represented the space between the superior and inferior bridging leaflet, which may extend from the site that the two leaflets cross the interventricular septum, to the points of coaptation at their free edges.

  
  
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  TV leaflet immobility: This represented the septal leaflet that appeared to be tethered down to the septum by the supporting apparatus.

Data Documentation

The reviewers recorded data on an information sheet that had a diagram of either the left AV or TV.

Statistical Analysis

For the left AV valve, there were very few patients with morphologic MVs, compared with those with AV septal defects. Therefore, for analysis, the combination of the left-sided component of superior bridging and inferior bridging leaflets was considered as one and assigned as equal to the anterior leaflet of the MV, with both being called the anterior leaflet. The cleft in the left AV valve was considered separately. The mural leaflets in AV septal defects or posterior leaflets in morphologic MVs were considered equally. As well, findings on 2D TTE and 2D TEE were combined for analysis, because the combination represents the current standard approach to AV valve assessment prior to surgery. The sensitivity, specificity, and accuracy of 2D and real-time 3D echocardiographic evaluation for leaflet structure and mechanisms of regurgitation were calculated using surgical findings as the reference standard. The sensitivity, specificity, and accuracy of 2D echocardiographic and surgical evaluation for the sites of the regurgitant jets were calculated with real-time 3D color Doppler as the reference standard. Color Doppler was chosen as the reference standard because it is a sensitive method to detect AV valve regurgitation and is obtained under physiologic conditions with the beating heart. Analyses were performed using Statcel 2003 (OMS, Saitama, Japan).