Key Words
Aortic root - Aortic valve replacement - Freestyle - Root pseudoaneurysm - Xenograft
- Cabrol technique
Introduction
Aortic root pseudoaneurysms are uncommon but highly morbid complications of the Medtronic
Freestyle® aortic root bioprosthesis (Medtronic, Inc., Minneapolis, MN, USA) and their
repair typically entails a technically difficult aortic root replacement, given adhesions
and loss of tissue planes around the coronary buttons and coronary arteries. In confronting
root pseudoaneurysms one has to rely on preoperative imaging and have a good primary
and secondary plan for managing the aortic root. We present our approach to managing
an aortic root pseudoaneurysm originating from a porcine xenograft.
Case Presentation
A 70-year-old Caucasian female presented with new-onset systolic murmur and shortness
of breath three years after undergoing aortic root replacement using a 27-mm Medtronic
Freestyle® stentless bioprosthesis (Medtronic, Fridley, Minnesota) for annular dilation
and severe aortic regurgitation.
Computed tomography (CT) with intravenous contrast revealed a large complex pseudoaneurysm
of the aortic root; transesophageal echocardiogram confirmed the findings and demonstrated
severe aortic regurgitation ([Fig 1]). The pseudoaneurysm had two components: one originating anteriorly near the right
sinus of Valsalva measuring 3 × 1.5 × 2.5 cm, and the second originating more posteriorly
in the noncoronary sinus of Valsalva and into the left sinus near the origin of the
left main coronary artery measuring 2.4 × 0.8 × 1.8 cm ([Fig. 2]). The overall diameter of the aortic root including the pseudoaneurysm was 6.5 cm.
The patient underwent reoperative aortic root replacement with complete excision of
the Freestyle® stentless bioprosthesis and implantation of a 28-mm Dacron Hemashield
tube graft (Meadox Medicals, Inc., Oakland, New Jersey, USA).
Figure 1. A. Computed tomography of chest (coronal view) with intravenous contrast showing
a pseudoaneurysm of the aortic root. B. Transesophageal ultrasound showing the pseudoaneurysm
of the aortic root and the perforations marked by the arrow.
Figure 2. A. Artist's rendering showing the two perforations of the porcine homograft. B. Artist's
rendering showing the coronary buttons, and the 12-mm Dacron graft anastomosis to
the left coronary button and saphenous vein graft to the right coronary artery. C.
Artist's drawing showing the creation of a stented valve-Dacron conduit by sewing
a bioprosthetic valve into the Dacron graft that has been folded over itself. Once
the folded Dacron graft is straightened it creates a skirt to anastomose to the aortic
root. D. Anastomosis of the composite Dacron/valve graft to the aortic root using
mattress-pledgeted sutures. E. Intraoperative picture showing the final appearance
of the replaced aortic root. The arrowhead marks the left main coronary artery Cabrol anastomosis to the neoaorta. The arrow marks the saphenous vein graft to the right coronary artery proximal anastomosis
to the neoaorta.
Surgical Technique
Cannulation for cardiopulmonary bypass was performed via a right axillary artery anastomosis
to an 8-mm Dacron Hemashield tube graft (Meadox Medicals, Inc, Oakland, New Jersey,
USA) to which the arterial cannula was connected and a long femoral venous cannula
for drainage positioned using transesophageal echo guidance, with the tip at the junction
of the superior vena cava and right atrium. The chest was reentered using an oscillating
saw and a segment of right saphenous vein was harvested for possible coronary reconstruction.
Following extensive adhesiolysis, the aorta was cross-clamped immediately proximal
to the innominate artery. The heart was arrested with antegrade cardioplegia and the
arrest was maintained with intermittent retrograde cardioplegia, accompanied by topical
cooling. The aorta was transected in the mid ascending portion, allowing us to confirm
that the distal aorta was intact. Inspection of the root showed that the valve had
been destroyed by presumed previous endocarditis, although there were no signs of
active infection and intraoperative Gram's stain and cultures were negative. Inspection
of the Freestyle® stentless bioprosthesis confirmed our preoperative CT scan findings
of a large wall defect in the noncoronary sinus and a second defect in the right coronary
sinus. The right and noncoronary leaflets of the bioprosthesis were almost completely
unhinged and prolapsing into the ventricle leading to aortic regurgitation. The Freestyle®
stentless bioprosthesis was removed completely while preserving both coronary buttons
(
[Fig. 2]
). Dissection of the left main coronary artery could not be performed beyond the ostium
because of its dense adhesions to the pulmonary artery, so a modification of the Cabrol
technique with an end-to end anastomosis of the left button to a 12-mm woven Dacron
Hemashield tube graft was used (
[Fig. 2]
). The right coronary ostium was densely adhered to its surrounding tissues; thus,
a saphenous vein graft was anastomosed end-to-side to the right coronary 2 cm distal
to the ostium and the ostium was then oversewn with a 4-0 polypropylene suture ([Fig. 2]).
The end of a 28-mm Dacron Hemashield tube graft (approximately 1.5 cm) was everted/folded
over itself in an elephant trunk fashion to create a proximal “skirt.” A 21-mm Magna
valve was sewn to the edge of the everted portion of the graft, initially with three
simple tacking sutures at 120-degree intervals, then with a running 4-0 polypropylene
circumferentially ([Fig. 2]). The graft “skirt” was then rolled down providing 1 cm of Dacron graft proximal
to the valve ([Fig. 2]). A total of 18 2-0 pledgeted, braided polyester sutures were brought outside to
inside of the ventricular outflow tract with no gaps between. The annular sutures
were then brought through the Dacron skirt below the bioprosthetic valve from inside
to outside to attach the graft, and tied to secure the composite valve-graft to the
ventricular outflow tract ([Fig. 2]). The distal anastomosis was performed using an outside felt buttress and 3-0 polypropylene
in a running fashion. The left main conduit was measured to reach the anterior aspect
of the neoaorta from the left side, as this provided a smooth pathway for reconstruction
and was anastomosed to the 28-mm Dacron graft using a 4-0 polypropylene suture ([Fig. 2], arrowhead). The saphenous vein graft proximal anastomosis to the neoaorta was performed
in a standard end-to-side fashion ([Fig. 2], arrow). With the reconstruction completed, we placed a root vent in the neoaorta
and de-aired the heart.
Total cross-clamp time was 2 hours and 17 minutes. The patient had an uneventful postoperative
period and was discharged on postoperative day 10. Empiric intravenous antibiotic
therapy was continued for 6 weeks postoperatively because of presumed culture-negative
endocarditis. The patient was found to be doing well at 1-month and 6-month follow-up.
Discussion
We describe the repair of an aortic root pseudoaneurysm arising from a Medtronic Freestyle®
porcine graft (Medtronic, Fridley, Minnesota, USA) secondary to primary graft perforation
in two areas. Our repair consisted of replacing the aortic root and reimplanting the
left main and right coronary arteries. Previous reports have described pseudoaneurysm
formation after anastomotic dehiscence[1]; others encountered true graft deterioration and perforation[2]
[3], and even traumatic disruptions have been described[4]. Isolated pseudoaneurysms of coronary buttons can be repaired using the technique
previously described by Schmoker and Miller[5], but in the current case, the valve needed to be replaced as well. Noncoronary sinus
of Valsalva perforations and pseudoaneurysms have been described[2]
[3], with one report identifying two defects in the biograft itself[3], as we did. Repair of the perforation has been successfully done in the absence
of infection[5] but usually requires an aortic root replacement. We elected to perform a Cabrol-type
reimplantation of the coronary arteries given the dense adhesions impeding their dissection
and hindering their length. A valve-Dacron graft conduit was created with a proximal
skirt to facilitate proximal graft anastomosis and allow the aorto-ventricular junction
to retain its flexible nature without myocardium contracting against a rigid structure,
thus serving as a shock absorber and improving hemostasis. This skirted Dacron graft
technique would also allow a future aortic valve replacement to be performed without
the need to perform a root replacement by simply cutting the running and the three
tacking sutures holding the bioprosthesis in place.
