Open stent grafting for complex diseases of the thoracic aorta: clinical utility

Hybrid Technologies for Reconstruction of Proximal Aortic Dissection

The aim of the study is to evaluate the efficacy of various types of hybrid technology in compare to the classical repair of the aortic arch of type I aortic dissection treatment in the in-hospital period.

Materials and Methods

A retrospective observational study has been conducted, the results of surgical treatment of 213 patients with DeBakey type I aortic dissection operated on within the period from 2001 to 2017 were compared. Patients were divided into three groups: in group 1, patients undergone a hemiarch type of aortic repair or the total arch replacement (n=121); in group 2, a hemiarch aortic reconstruction and implantation of bare metal stent was performed (n=55); in group 3, a frozen elephant trunk technique was used (n=37). Taking into consideration the retrospective character of the investigation and nonequivalence of the groups by separate characteristics, they were equalized to improve the reliability of the results using the PSM (propensity score matching) pseudorandomization method. As a result, three groups of comparison were formed which were equalized by the PSM method and called PSM 1, 2, and 3. The mortality and complication rate in the in-hospital period, as well as the frequency of false lumen thrombosis development depending on the treatment method, have been analyzed.

Results

The mortality rate in the PSM 1 group was 15 patients: group 1 (standard technique) - 10 patients (9%), group 2 (uncoated stents) - 5 patients (11%). A significant difference was found in the number of major bleedings (group 1 - 8%, group 2 - 21%, p=0.031) and cases of bowel ischemia (group 1 - 1%, group 2 - 9%, p=0.028). Complete false lumen thrombosis of the thoracic aorta was observed significantly more often in group 1 than in group 2 (22% vs 5%, p=0.015).In the examined group PSM 2, hospital mortality rate was 4 patients: group 1 - 3 patients (12%), group 3 - 1 patient (3%). No differences between the groups were found in the number of complications. In group 3, complete false lumen thrombosis of the thoracic aorta was observed in 59% of cases, whereas in group 1 it was found only in 4% of patients (p<0.001).In comparison group PSM 3, the mortality was 8 patients: group 2 - 5 patients (11%), group 3 - 3 patients (9%). The number of neurological complications differed significantly: in group 2 - 27%, in group 3 - 6% (p=0.019). Besides, 3% of cases of complete false lumen thrombosis were found in group 2, while there appeared 55% (p<0.001) of such patients in group 3.

Conclusion

The comparative analysis showed that the use of bare metal stents and hybrid prostheses demonstrated a comparable low level of in-hospital mortality compared to the standard surgical technique of aortic arch reconstruction. At the same time, the use of the bare metal stents is associated with a higher rate of perioperative complications (bleeding, postoperative bowel ischemia, neurological complications) compared to the standard treatment and repair of the aortic dissection using hybrid prostheses. Complete thrombosis of the false lumen occurred significantly less commonly in case of using bare metal stents than with standard treatment and hybrid prostheses.

Two Cases of Endovascular Repair with the Stent Graft for Retrograde Type A Acute Aortic Dissection with Complications

Thoracic endovascular aortic repair (TEVAR) is used to treat retrograde type A acute aortic dissection (RTAAD). In case 1, a 52-year-old man, who was conservatively managed, reported worsening back pain. Emergency TEVAR was performed 7 days after onset. After deploying two GORE Conformable TAG (CTAG) in the descending aorta, his symptoms disappeared. In case 2, a 52-year-old man with progressive worsening resistant hypertension, renal dysfunction, and respiratory failure despite maximal medical therapy underwent TEVAR 8 days after onset. A CTAG was deployed from the left subclavian artery under rapid pacing, and two Zenith Dissection stents were placed, which resolved complications. In both cases, after 6 months, computed tomography (CT) scan showed complete resorption of the false lumen in the ascending aorta. TEVAR for RTAAD with complete thrombosis of false lumen in the ascending aorta can be an alternative to surgery when the primary tear is located in descending aorta.

De-airing an open stent graft to potentially reduce spinal cord injury

We have occasionally observed a bubble leaving the suture line of an open stent graft; hence, we hypothesized that de-airing an open stent graft could potentially reduce spinal cord injury. Postoperative computed tomography often showed residual air in thoracic aortic aneurysms, confirmed by the presence of a certain amount of air in an open stent graft in a dry lab. We filled CO₂ in the sterilized package of an open stent graft and subsequently filled it with saline, which absorbed the CO₂ and entered into the gap of the graft. The clinical benefit of de-airing an open stent graft to reduce the incidence of spinal cord injury needs to be evaluated.

Mechanical and geometrical determinants of wall stress in abdominal aortic aneurysms: A computational study

An aortic aneurysm (AA) is a focal dilatation of the aortic wall. Occurrence of AA rupture is an all too common event that is associated with high levels of patient morbidity and mortality. The decision to surgically intervene prior to AA rupture is made with recognition of significant procedural risks, and is primarily based on the maximal diameter and/or growth rate of the AA. Despite established thresholds for intervention, rupture occurs in a notable subset of patients exhibiting sub-critical maximal diameters and/or growth rates. Therefore, a pressing need remains to identify better predictors of rupture risk and ultimately integrate their measurement into clinical decision making. In this study, we use a series of finite element-based computational models that represent a range of plausible AA scenarios, and evaluate the relative sensitivity of wall stress to geometrical and mechanical properties of the aneurysmal tissue. Taken together, our findings encourage an expansion of geometrical parameters considered for rupture risk assessment, and provide perspective on the degree to which tissue mechanical properties may modulate peak stress values within aneurysmal tissue.

Stented balloon fenestration before entry repair using the frozen elephant trunk technique for chronic aortic dissection

Endovascular fenestration on the abdominal aorta is effective for preventing visceral malperfusion in aortic dissection. We report a case of stented balloon fenestration before residual entry repair using the frozen elephant trunk technique for chronic aneurysmal dissection after ascending aortic replacement for DeBakey I aortic dissection. We recognized poor communication between the true lumen and false lumen in the abdominal aorta, and visceral perfusion depended almost entirely on the proximal large entry. Therefore, we scheduled catheter angioplasty on the small re-entry before upstream entry closure. After balloon angioplasty using a PTA catheter, a 10-mm × 4-cm self-expandable stent was deployed at the re-entry. We performed open surgery 5 days after angioplasty. Computed tomography after entry repair showed complete thrombosis of the false lumen on the descending aorta, and the celiac and superior mesenteric arteries were supplied via the abdominal re-entry stent. Stented balloon fenestration before entry repair using frozen elephant trunk with chronic aortic dissection was effective for preventing visceral malperfusion.

A Case of Traumatic Retrograde Type A Aortic Dissection Accompanied by Multiorgan Injuries

A 75-year-old woman was involved in a traffic accident and suffered retrograde type A aortic dissection, multiple rib fractures, and grade II hepatic injury accompanied by intraperitoneal bleeding. We performed total arch replacement using an open stent graft with cardiopulmonary bypass and circulatory arrest. This procedure requires anticoagulation and hypothermia, which are principally contraindicated in severe trauma patients. However, this situation was resolved by managing the patient non-operatively for 7 days, confirming the stabilization of other injured organs, and then performing the surgery. She required prolonged postoperative rehabilitation; however, she recovered steadily.

The number of cardiovascular surgeries in Japan may decrease after 2020

The expected future number of cardiovascular operations is estimated based on the predicted Japanese population and the rate of cardiovascular surgery performance calculated from 16845 cases treated by the Nagoya University group of hospitals between 2001 and 2013. The population of <20-year-old individuals has decreased since 1990, while that of 20-64-year-old individuals has also decreased since 2000. The population of 65-79-year-old individuals is expected to peak in 2020, with only the population of ≥80-year-old individuals expected to increase until 2040. The performance rate of cardiovascular surgery per 100,000 population is low in the 20-64-year-old group and increases to reach a peak in the elderly population of 70-74-year-old individuals in valvular heart disease (55.5), ischemic heart disease (54.5) and thoracic aortic aneurysm (31.9) and decreases to about half those values in the ≥80-year-old age group. The number of cardiovascular operations (all types) per 100,000 was 40.6 in 2002, 42.1 in 2006 and 46.6 in 2010. The total number of expected cardiovascular operations is increasing slightly and will reach a peak in 2020 with an estimated 61,506 operations. It then decreases gradually to reach 55966 in 2035, on the premise that the cardiovascular surgery performance rate does not change from the present time. In order to maintain and expand to meet the medical needs of cardiovascular surgery, it is crucial that an effort be made to increase the cardiovascular surgery performance rate, especially in octogenarian patients.

Open Stented Grafts for Frozen Elephant Trunk Technique: Technical Aspects and Current Outcomes

With growing experience in patients with aneurysms and dissections in the arch and proximal descending aorta, the frozen elephant trunk (FET) technique has been shown to be safe and effective, and has achieved favorable short to mid-term outcomes. As the FET technique is gaining wider acceptance, there is a growing need for versatile, technically simple, and highly durable open stented grafts involving less complicated deployment mechanisms enabling use in various indications. This paper gives a brief review on the technical aspects and clinical outcomes of currently available open stented grafts used in the FET technique, including the E-vita Open Plus, Thoraflex Hybrid, Cronus, and J Graft. While none of these grafts can claim to be an ideal device, technology continues to improve towards this goal. As newer devices and systems are developed, more widespread use of the FET technique can be expected; such progress promises to improve the clinical outcomes and quality of life for patients with complex aortic diseases.

Long-term results of open stent-grafting using a Matsui-Kitamura stent to treat thoracic aortic aneurysm

PURPOSE

We describe a retrospective study of initial and long-term outcomes with an open stent grafting (OSG) with a Matsui-Kitamura stent for treating thoracic aortic aneurysm.

METHODS

Between August 2005 and September 2013, 50 patients with aortic arch disease extending to the descending aorta underwent OSG. Circulatory arrest with total cardiopulmonary bypass and selective cerebral perfusion were used, and the aorta was transected between the brachiocephalic and left subclavian artery. The stent-graft was inserted, sutured to a transected aortic edge, and anastomosed to a four-branched arch graft. Preoperative, operative, and short- and long-term postoperative data were obtained from the patients' medical records.

RESULTS

The perioperative (within 30 days) mortality rate was 8%. Two patients (4%) had a stroke and 5 patients (10%) had a spinal cord injury resulting in paraplegia or paraparesis (1 patient each) or transient paraplegia (3 patients). Actuarial survival rates at 1, 3, 5, and 7 years postoperatively were 87.8%, 78.3%, 70.7%, and 65.3%, respectively; the rates of freedom from an aortic event were 100%, 89.1%, 82.2%, and 74.7%. There were no complications related to use of the stent-graft.

CONCLUSION

Our OSG method provided durable results in patients treated for thoracic aortic aneurysm, with few adverse events.

How to prevent spinal cord injury during endovascular repair of thoracic aortic disease

The incidence of spinal cord injury in thoracic endovascular aortic repair (TEVAR) has been 3-5 % from recent major papers where sacrifice of the critical intercostal arteries is inevitable by a stent graft. Hemodynamic stability, which depends on a network of blood vessels around the cord is most important not only during but also after stent-graft deployment. High risk factors of spinal cord injury during endovascular aortic repair are (1) coverage of the left subclavian artery, (2) extensive coverage of long segments of the thoracic aorta, (3) prior downstream aortic repair, (4) compromising important intercostal (T8-L1), vertebral, pelvic and hypogastric collaterals, and (5) shaggy aorta. Preoperative, intraoperative, and postoperative managements have been required to prevent spinal cord injury with TEVAR. For imaging assessment of blood supply to spinal cord including Adamkiewicz artery, prophylactic cerebrospinal fluid drainage is mandatory, and monitoring motor-evoked potential is recommended for high risk factors of spinal cord injury. Mean arterial pressure should be maintained over 90 mmHg after stent-graft placement for a while to prevent delayed spinal cord ischemia in high-risk patients of spinal cord ischemia. Finally, because spinal cord injury during TEVAR is not rare and negligible, perioperative care during TEVAR should be strictly performed according to the protocol proposed by each cardiovascular team.

Elephant trunk technique for hybrid aortic arch repair

The original elephant trunk technique was developed by Borst in 1983 for the treatment of aortic arch aneurysms. This technique reduced operative risks, but was associated with cumulative mortality rates of 6.9 % for the first stage and 7.5 % for the second stage. Patients also waited a long time between two major surgical procedures. Only 50.4 % of patients underwent the second-stage surgery, and there was a significant interval mortality rate of 10.7 %. With the advent of stent-graft techniques, two different hybrid elephant trunk techniques were developed. One technique is first-stage elephant trunk graft placement followed by second-stage endovascular completion. The conventional elephant trunk graft provides a good landing zone for the stent-graft, and endovascular completion is a useful alternative to conventional second-stage surgery. This method has few major complications, and a postoperative paraplegia rate of 1.1 %. The other technique is the frozen elephant trunk technique. This technique eliminates the need for subsequent endovascular completion, and is particularly useful for the treatment of acute type A dissection because it can achieve a secure seal. However, it is associated with a higher rate of spinal cord ischemia than other methods such as the original elephant trunk technique. The left subclavian artery (LSA) is often lost when performing a hybrid elephant trunk procedure. Revascularization of the LSA should be performed to prevent arm ischemia and neurological complications such as paraplegia or stroke, although the level of evidence for this recommendation is low.