From the Departments of *Cardiac Surgery and †Radiology, Herz-und Gefäßklinik Bad Neustadt—Germany, Bad Neustadt, Germany; and ‡Department of Pediatric Cardiology, Herzzentrum, Universät Leipzig-Germany, Leipzig, Germany.
Accepted for publication January 11, 2010.
Address correspondence and reprint requests to Anno Diegeler, MD, PHD, Department of Cardiac Surgery, Herz-und Gefäßklinik Bad Neustadt, Abteilung Herzchirurgie, Salzburger Leite 1, Bad Neustadt 97616 Germany. E-mail: email@example.com.
Stenting of the Shelhigh pulmonary conduit was performed 2 years after a Ross procedure because of a stenosis of the distal segment. We used the new Siemens Artis Zeego technology. A precise placement of the stent to release the stenosis within the distal segment simultaneously retaining a competent valve was possible by using the Dyna-computed tomography technology. The early onset of a stenosis of the Shelhigh xenograft in the pulmonary position is alarming, thus, its use can not be recommended for a replacement of the pulmonary valve.
A 56-year-old man became symptomatic 2 years after a Ross procedure. Cardiovascular evaluation revealed a stenosis of the Shelhigh xenograft valved conduit, which was used to replace the pulmonary valve. The gradient over the stenosis was measured as 45 mm Hg causing a right ventricular pressure of 65 mm Hg, a consecutive right ventricular enlargement, and a mild tricuspid incompetence. Pulmonary angiography revealed the location of the stenosis at the distal suture line between the conduit and the pulmonary bifurcation (Fig. 1). The stenosis did not seem to involve the valve containing segment of the conduit. Therefore, an isolated angioplasty and stent placement of the distal segment of the conduit was intended and performed in a “hybrid” operation room under surgical stand by.
Procedure and Result
The procedure was performed using the new Siemens Artis Zeego angiography technology enabling a rotation angiography for 3D reconstruction, the so-called DYNA-computed tomography (CT). General anesthesia, ventilators arrest, and rapid ventricular pacing were established for rotation angiography and placement of the stent. By 3D reconstruction of the pulmonary anatomy, an exact measurement of the length of the stenosis was possible (Fig. 2). At 69-degree left anterior oblique (LAO), the best angle of visualization of the target area could be achieved. Having the bifurcation and the valve containing segment of the conduit in an exact plane view is crucial for precise placing of the stent, because it is of most importance to avoiding any interference between the stent and the cusps of the valve. A 8-Zigs, 34-mm CP-Stent (NuMed, Inc., Hopkinton, NY) could be placed under rapid pacing exactly between the bifurcation and the upper commissures of the valve (Fig. 3). After angioplasty, the gradient over the pulmonary conduit dropped from 45 to 16 mm Hg, leaving a remaining right ventricular pressure of 28 mm Hg. Correct placement of the stent and the unrestricted movements of the cusps of the conduit could be confirmed by a finally performed DYNA-CT, again under rapid ventricular pacing (Fig 4).
Availability and storage of pulmonary homografts is limited, complex, and costly. The use of a biologic porcine xenograft valved conduit could be a favorable alternative, notably in adult patients who undergo a Ross procedure.1–3 Such a porcine xenograft conduit, namely Shelhigh No-React (Shelhigh, Inc., Millburn, NJ), was available until its production was interrupted by an interference of the US Food and Drug Administration.
We present the case of a 56-year-old man with a rather early occurrence of a severe stenosis of Shelhigh No-React porcine xenograft valved conduit (size 27 mm) 2 years after its implantation during a Ross procedure.
Although this conduit was proved do be safe and effective,3 the occurrence of a stenosis in the midterm follow-up has been reported in children. Such a stenosis usually involves the distal segment of the conduit at the site of the suture line toward the native pulmonary artery.4 The pathology for these phenomena is not well understood. In children, all xenograft valve prostheses show the tendency of midterm degeneration. In young ages and in small prostheses, sizes increased shear stress, and an inflammatory response to the foreign tissue is presumed.5,6 However, a stenosis in a widely larger adult conduit may not be expected at an early stage, especially in the face of the particular preprocessing of these valves to avoid an early anticalcification (Shelhigh No-React). The location of the presented stenosis, however, occurred at the typical site at the distal suture line.
To release this kind of stenosis, a reoperation (and the use of a homograft) or angioplasty and stent placement are necessary. To avoid an early second operation, we favored an angioplasty procedure. Because surgical stand by is recommendable, we performed the procedure in a hybrid operation room. This room has the new Siemens Artis Zeego available, which enables an intraoperative 3D display by using the Siemens DYNA-CT feature.
In the presented case, this technology has been proved to be of particular value for an exact evaluation of the target area, to estimate the necessary length of the stent, and to determine the exact stent position. The DYNA-CT protocol includes a period of rapid cardiac pacing (180–200 beats/min), which takes around 15 seconds. We used the overlay technology, another feature, to determine the length of the stent. This is crucial to avoid any interference with the cusps of valve within the proximal part of the conduit. In addition, 3D rotation angiography revealed to be very helpful tool to determine the best angle for fluoroscopy during the stent placement, which was 69 degree/LAO in the presented case. Rapid pacing is also recommendable during the maneuver of the dilatation and stent placement within the target area.
The use of a xenograft conduit as a favorable alternative to a homograft in a Ross procedure of an adult patient seems to be questionable.7 Because the presented case is the second one we have seen 2 years after its implantation during a Ross procedure, a word of caution is indicated. However, the angioplasty of the stenotic area was successful in the first patient and also in the second one. This would be our procedure of choice to solve the problem, especially because the new angiography features of DYNA-CT in combination with the new Siemens Artis Zeego technology facilitates the procedure. Even in case of the not presumably secondary narrowing of the valve containing segment of the still remaining xenograft conduit, the implantation of another valve containing stent, namely Melody, (Medtronic, Inc., Minneapolis) would be the next step to avoid an early secondary operation in this young adult patient.8
A Shelhigh porcine xenograft valved conduit showed an early stenosis 2 years after its implantation during a Ross procedure in an adult patient. The location was similar to those known from children at the site of the distal suture line. To avoid an early reoperation, angioplasty and stenting of the stenotic segment could be proved to be feasible and effective by releasing most of the gradient without interfering with cusps of the remaining valve of the conduit. Intraoperative 3D reconstruction of the target area using the latest Siemens Artis Zeego technology offers a perfect setting for precise stent placement. This technology implemented in a hybrid operation room provides the best safety for the intervention by a real-time surgical backup. As far as the Shelhigh xenograft valved conduit is concerned as a pulmonary substitute, we like to express our concerns that stenosis of the conduit may evolve even shortly after surgery.
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