The pulmonary-to-systemic flow ratio (Qp/Qs) was calculated to be 1.3. The defect was deemed small and restrictive with a peak shunt velocity of 5.2 m/s and a peak gradient of 109 mm Hg between the LV and RV. Based on 2D and 3D measurements, a 10 × 8 mm Amplatzer Duct Occluder (St Jude Medical, St. Paul, MN) device was chosen.
The procedure was accomplished under continuous TEE guidance (Supplemental Digital Content 2, Video 2, http://links.lww.com/AA/C80), and the final device deployment was done in an antegrade fashion (Figure 3A, B). Postdeployment, a well-seated occluder was seen on TEE without any interference to the function of the AV and TV, and there was no residual shunting on color-flow Doppler (Supplemental Digital Content 3, Video 3, http://links.lww.com/AA/C81).
Membranous VSDs are the most common types, of which approximately 75% lie in the left ventricular outflow tract just below the noncoronary cusp of the AV.1 The term “perimembranous” refers to those that extend into the adjacent muscular septum. Typically, pmVSDs occur as a single defect and are seen at the 6–8 o’clock position in the midesophageal (ME) RV inflow–outflow view adjacent to the TV.
A VSD is generally considered nonsignificant and restrictive when the maximum diameter is <25% of the aortic annulus, Qp/Qs is <1.5,2 and pulmonary artery systolic pressure is <40 mm Hg. Typically, in a restrictive lesion, the peak flow velocity is >4 m/s and the pressure gradient is >60 mm Hg. Based on the above criteria, but with the exception of diameter, our patient’s VSD would be considered restrictive. However, since the defect had grown significantly from 3 to 9 mm over the last 8 years, the LV was dilated, and the patient experienced progressive dyspnea on exertion, a decision was made to proceed with percutaneous closure.
In the past, pmVSDs were not readily amenable to percutaneous closure because of their proximity to the TV and AV, the potential for conduction defects, and the high likelihood of residual shunts. However, advances in occluder devices have improved safety and increased their use. The Amplatzer pmVSD occluder, with its asymmetrical disks and long waist, is specifically suited for this type of VSD3; however, it is not yet available in the United States. Therefore, the interventional cardiologist used the Amplatzer Duct Occluder off-label because of reported successful application.4
Before the procedure, it is important to accurately size the defect to avoid device-defect mismatch because often these defects are oval, with different surface dimensions when seen from the LV or RV perspective, and may even have >1 exit hole. The defect is best measured during TEE in the ME 2-chamber (90°, with a slight clockwise turn of the probe that brings the AV into view while foreshortening the LV), AV long-axis (AV LAX) (120–140°), ME AV short-axis (SAX) (25–45°) views, and/or the ME RV inflow–outflow views. However, off-axis views and nonstandard imaging planes may be needed to properly align the defect in cross-section and measure its diameter. Considerable variation of the VSD size has been seen during the cardiac cycle, with higher measurements during diastole as compared to systole.5,6
It is also important to note the proximity of the defect to the TV and AV.7 In the past, a defect that was <5 mm from the aortic annulus was considered to be high risk for postdeployment AV dysfunction. However, with modern devices, device closure is possible even with an aortic rim of 1 mm.7 In our case, there was a thin but definite rim of tissue between the VSD and the aortic annulus, which was ≥1 mm. Baseline assessment of the AV and TV should always be done before percutaneous device closure. The modified ME 2-chamber view described above, when used with simultaneous orthogonal imaging, will allow concurrent visualization of the VSD, AV, and TV.
While 2D is quick and easy, real-time 3D TEE can provide a better understanding of the complex structure of the septum. The 3D zoom “en-face” view allows for imaging of the septum from both the LV and RV, thus enabling a more accurate sizing of the defect and a clearer perspective of the contiguous structures.8 The 3D full-volume dataset is best captured from the ME AV LAX view. Using multiplanar reconstruction, this dataset can be sliced into 3 orthogonal planes, namely, sagittal, coronal, and cross-sectional. While aligning the sagittal and coronal planes parallel to the LAX of the VSD (from the LV or RV perspective), the cross-sectional (SAX) plane is adjusted to intersect the shunt at the desired level. Precise edge-to-edge, anterior–posterior, and side-to-side measurements can then be made in the cross-sectional plane. Three-dimensional color with its excellent spatial resolution is useful in evaluating the presence, exact location, and severity of the residual shunts; however, it is limited by the frame rate and therefore temporal resolution.
During the procedure, real-time 2D and 3D TEE guidance is needed for placement of the guidewire, the snare retrieval catheter, as well as the occluder delivery sheath. Echocardiographers should be aware of reverberation, mirror, and side-lobe artifacts that may make it difficult to accurately locate and distinguish the device delivery sheath from the guidewires, which is generally less echogenic than the guidewires and looks like a hollow tube on echo. Before releasing the occluder, 2D with and without color Doppler and/or real-time 3D imaging in the ME AV LAX and ME RV inflow–outflow views, preferably with simultaneous orthogonal imaging, is required to ensure no device-induced TV or AV dysfunction.
Postdeployment, TEE is appropriate for checking residual shunts by 2D color Doppler AV LAX view as well as with agitated saline contrast study. A residual defect <3 mm in diameter is considered small9 and with device endothelialization may resolve over time.
We thank Rhonda Powell for the medical illustrations, and Lindsey Couture, RDCS, and Rhonda Compress, RDCS, for echocardiographic image acquisitions as well as the multiplanar reconstructions.
Name: Shvetank Agarwal, MD, FASE.
Contribution: This author was involved in the case; and helped write the manuscript, design the case report, acquire and interpret the transesophageal echocardiography (TEE) images and video loops, design the illustrations, and approve the final manuscript.
Name: Gyanendra K. Sharma, MD, FACC, FASE.
Contribution: This author helped write the manuscript, interpret the TEE images and video loops, and approve the final manuscript.
Name: Supawat Ratanapo, MD.
Contribution: This author helped edit the TEE loops and images and approve the final manuscript.
Name: Nadine Odo, BA, ELS.
Contribution: This author helped write and edit the manuscript and approve the final manuscript.
Name: Sean P. Javaheri, DO.
Contribution: This author was involved in the case; and helped acquire the TEE images and videos, edit the manuscript, and approve the final manuscript.
This manuscript was handled by: Nikolaos J. Skubas, MD, DSc, FACC, FASE.
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