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.