Discussion
Post-HTx dissection is rare and requires urgent surgical intervention
with high mortality (1). Ruptures that occur in the acute period are
dramatic and are due to tension in the suture line or aortic mismatch
(3). Proper adjustment and good alignment of the donor aorta will reduce
the tension at the suture line (5). These patients present with
shortness of breath, chest pain, back pain and dry cough. (5) However,
patients may be asymptomatic due to denervation. The development of
aneurysm or tear in the donor aorta prevents the dissection from
spreading towards the recipient aorta, and neurological problems may not
be seen (3,5).
Our patient had similar symptoms. If dissection occurs in donor tissue,
it can usually be detected in control echo or autopsies (4,5). Lang et
al have detected the incidence in childhood as 0.9%. This rate is
almost similar in adult patients. They stated that diagnosis is
difficult due to cardiac denervation (6). The situation is in the form
of painless dissection. There is no or minimal mediastinal bleeding due
to adhesions (3,6). The cause of dissection is not clear (3). However,
cross clamping trauma, de-airing needle location, connective tissue
diseases such as Marfan syndrome (2), donor and recipient aortic
mismatch, candida infection, secondary hypertension due to postoperative
immunosuppressive therapy (1,2,4), technical reasons, mediastinal heart
trauma, past percutaneous coronary intervention, or invasive
interventions (4,6) can be the cause. Frequent antibiotic use, central
catheter insertion, total parenteral nutrition are the most common
causes of candida infections (3,4,5). Donor hearts harvested from
Marfanoid, and Loeys-Dietze donors, the risk of dissection of the donor
aorta increases (5,6).
In our patient, dissection was found to be caused by the anastomosis
line. Although, dissection was reported mostly in the donor aorta (2,4)
in the literature, recipient aortic dissection was present in our case.
We think that the dissection of the suture line prevents it from
progressing to the donor aorta.
Although, no hypertension was present on the pre-transplant history. The
patient has used ACE inhibitor and Ca channel blocker in the last five
years for hypertension possibly due to immunosuppressive therapy. DM in
addition to hypertension can increase the risk even more. Hypertension
may trigger the development of dissection. Furthermore, a mismatch was
reported between the donor and the recipient’s aorta during the
patient’s initial surgery. This was the second risk factor. Iatrogenic
intimal trauma was ruled out. Because our patient did not undergo
angiography or invasive intervention before. Past infections and mycotic
causes may cause pseudoaneurysms. They are larger and develop in the
ascending aorta (3-5,8).
Coppola et al detected aortic dissection in two postmortem cases. In
these patients, they reported that the tear was in both donor and
recipient aorta and was caused by cross-clamping (8). Postmortem studies
or pathological examination of the extracted aneurysm tissue can be
beneficial illuminating in terms of etiology. Our patient did not have
any known connective tissue disease.
Donor aortic dissections are more likely to be retained as the
retrograde that develops downwards, and aortic insufficiency is a fatal
complication of such acute aortic dissections. It may require Bentall
and Cabrol procedure or valve protecting procedure such as David
(2,3,5,7,8-12). The Bentall procedure after HTX was first performed by
Schellemans et al (5). Since dissection developed from the anastomosis
line to the distal in our patient, the donor aorta was intact and there
was no aortic insufficiency. There was no need to interfere with the
valve. Leone et al applied the Bentall procedure and the Elephant Trunk
technique together in such cases (8). Supra-coronary ascending aorta and
hemi arcus replacement may be sufficient in cases like ours. (13)
Indeed, in our early thorax CT, we found that the false lumen was
completely thrombosed. Following HTx, ascending aortic aneurysms
developing in the native aorta were also be reported. Ascending and hemi
arch replacement were performed for the treatment (14).
We recommend that the donor aorta should be shortened properly during
the trimming procedure so that the aortic anastomosis line is not
stretched. Infection is also a major cause. Hypertension and DM due to
immunosuppressive therapy must be treated sufficiently. Such patients
require rapid and aggressive surgical treatment for optimal long-term
results. As in other dissection cases, cardiac team should be prepared
for all kinds of scenarios.