Yukitoshi Shirakawa

Long-term results of the open stent-grafting technique for extended aortic arch disease

OBJECTIVE This report elucidates the long-term safety and effectiveness of extended aortic arch replacement with an open stent-grafting technique from our 12 years of experience. METHODS From 1994 to 2004, 126 patients (mean age 67.8 years) with different pathologic conditions of the aortic arch with extension to the descending aorta (57 dissections [acute/chronic = 31/26] and 69 aneurysms) were operated on with an open stent-grafting technique. During deep hypothermic circulatory arrest with selective cerebral perfusion, the stent graft was delivered through the transected proximal aortic arch, and arch replacement with a 4-branched prosthesis was performed. RESULTS Operative mortality within 30 days was 3.2%. Perioperative morbidity included 7 (5.6%) strokes and 8 (6.3%) spinal injuries (paraplegia in 3, transient paraparesis in 5). Sixty-three percent of the patients were extubated within 24 hours. In long-term follow-up (mean 60.4 +/- 36.5 months, maximum 153 months), survival was 81.1%, 63.3%, and 53.7% at 1, 5, and 8 years. Five (3.9%) late endoleaks were observed but treated with successful additional endovascular repair. Freedom from endoleaks was 98.0%, 91.1%, and 91.1% for 1, 5, and 8 years, respectively. CONCLUSION Long-term observation showed safety and good durability of the open stent-grafting technique for aortic arch disease. This technique could be an attractive treatment option for aortic arch aneurysm with distal extension and aortic dissection requiring aortic arch replacement.

Tissue- and Plasma-Specific MicroRNA Signatures for Atherosclerotic Abdominal Aortic Aneurysm

Background Atherosclerotic abdominal aortic aneurysm (AAA) is a progressive, gradual aortic rupture that results in death in the absence of surgical intervention. Key factors that regulate initiation and progression of AAA are unknown, making targeted interventions difficult. MicroRNAs play a fundamental role in atherosclerosis, and atherosclerotic coronary artery disease is characterized by tissue- and plasma-specific microRNA signatures. However, little is known about microRNAs involved in AAA pathology. This study examined tissue and plasma microRNAs specifically associated with AAA. Methods and Results AAA and normal wall tissues were sampled from patients undergoing AAA repair (n=13; mean age, 68±6 years) and aortic valve replacement surgery (n=7; mean age, 66±4 years), respectively. MicroRNA expression was assessed by high-throughput microRNA arrays and validated by real-time polymerase chain reaction for individual microRNAs that showed significant expression differences in the initial screening. MicroRNAs related to fibrosis (miR-29b), inflammation (miR-124a, miR-146a, miR-155, and miR-223), and endothelium (miR-126, let-7 family members, and miR-21) were significantly upregulated in AAA tissue. Significant negative correlations were seen in expression levels of monocyte chemoattractant protein-1 and miR-124a, -146a, and -223; tumor necrosis factor-α and miR-126 and -223; and transforming growth factor-β and miR-146a. Expression of microRNAs, such as miR-29b, miR-124a, miR-155, and miR-223, that were upregulated in AAA tissue was significantly reduced in plasma of patients with AAA (n=23; mean age, 72±9 years) compared to healthy controls (n=12; mean age, 51±11 years) and patients with coronary artery disease (n=17; mean age, 71±9 years). Conclusions The expression of some microRNAs was specifically upregulated in AAA tissue, warranting further studies on the microRNA function in AAA pathogenesis and on the possibility of using a microRNA biomarker for AAA diagnosis.

In situ tissue regeneration using a novel tissue-engineered, small-caliber vascular graft without cell seeding

OBJECTIVE Various types of natural and synthetic scaffolds with arterial tissue cells or differentiated stem cells have recently attracted interest as potential small-caliber vascular grafts. It was thought that the synthetic graft with the potential to promote autologous tissue regeneration without any seeding would be more practical than a seeded graft. In this study, we investigated in situ tissue regeneration in small-diameter arteries using a novel tissue-engineered biodegradable vascular graft that did not require ex vivo cell seeding. METHODS Small-caliber vascular grafts (4 mm in diameter) were fabricated by compounding a collagen microsponge with a biodegradable woven polymer tube that was constructed in a plain weave pattern with a double layer of polyglycolic acid (core) and poly-L-lactic acid (sheath) fibers. We implanted these tissue-engineered vascular grafts bilaterally into the carotid arteries of mongrel dogs (body weight, 20-25 kg). No anticoagulation regimen was used after implantation. We sacrificed the dogs 2, 4, 6, and 12 months (n = 4 in each group) after implantation and evaluated the explants histologically and biochemically. RESULTS All of the tissue-engineered vascular grafts were patent with no signs of thrombosis or aneurysm at any time. Histologic and biochemical examinations showed excellent in situ tissue regeneration with an endothelial cell monolayer, smooth muscle cells, and a reconstructed vessel wall with elastin and collagen fibers. CONCLUSION Our study indicated that this novel tissue-engineered vascular graft promoted in situ tissue regeneration and did not require ex vivo cell seeding, thereby conferring better patency on small-caliber vascular prostheses.

Long-term results of hybrid endovascular repair for thoraco-abdominal aortic aneurysms

OBJECTIVE The treatment of thoraco-abdominal aortic aneurysms (TAAAs) is extremely laborious, due to the surgical complexity of this condition. In particular, postoperative spinal paraplegia poses a severe complication that significantly lowers patients quality of life. In 1997, we devised a hybrid procedure consisting of extended endovascular aortic repair (EVAR) and visceral reconstruction. In this article, we report the long-term results obtained from this procedure. METHODS We conducted 1106 endovascular aortic repairs between 1997 and 2008. Among these, we selected 86 cases of TAAA. The mean patient age was 71.6 years. Preoperative complications included 19 cases of stroke, 22 cases of coronary artery disease (CAD) and 16 cases of chronic obstructive pulmonary disease (COPD). Cerebrospinal fluid drainage was initiated during the operation. We performed bypasses from the aortic bifurcation to abdominal visceral arteries, and deployed stent grafts to exclude the entire TAAA. RESULTS Operative time averaged 386 min. We lost two patients and encountered only one case of graft occlusion. Two patients had acute renal failure, but neither required a tracheostomy. Furthermore, no patients exhibited paraplegia or delayed paraplegia. We observed endoleaks in nine cases, and shrunken aneurysms in 73 cases. Long-term results included survival rates of 94.8%, 85.8%, 80.2% and 66.6% at 2, 5, 8 and 10 years, respectively. Only two patients died from aortic events. Rates of freedom from aortic events were 90.7%, 80.6%, 70.8% and 70.8% at 2, 5, 8 and 10 years, respectively. CONCLUSIONS The hybrid TAAA-repair protocol yielded satisfactory results. Although thorough follow-up is required for visceral bypass, this procedure could become the standard for TAAAs.

Hybrid endovascular aortic arch repair using branched endoprosthesis: The second-generation branched open stent-grafting technique

OBJECTIVE We advanced the open stent-grafting technique with a branched endoprosthesis, which reconstructs simultaneously the cervical branches and descending aorta within an acceptably short interval of deep hypothermic circulatory arrest. In this study, we evaluated the efficacy of this new technique and assessed the early and midterm results. METHODS From January 2004 to September 2007, the branched open stent-grafting technique was performed in 69 cases (55 men, average age 66.2 years, 36 degenerative aneurysms and 33 aortic dissections, 13 [18.8%] in emergency, 7 [10.1%] redo cases). Under deep hypothermic circulatory arrest, the branched endoprosthesis was delivered through the opened proximal aortic arch, and total arch repair was completed. To avoid cerebral embolism, retrograde cerebral perfusion was performed at the end of deep hypothermic circulatory arrest. RESULTS Average time of operation, cardiopulmonary bypass, and deep hypothermic circulatory arrest was 417, 130, and 36 minutes, respectively. A total of 124 cervical stent grafts were inserted and successfully delivered in 121 (97.6%). Operative mortality within 30 days was 3 (4.3%). The major postoperative complications involved 4 (5.8%) strokes and 2 (2.9%) spinal cord injuries. No aorta-related death was observed after discharge from hospital, and the survival was 90.9%, 88.8%, and 88.8% at 1, 2, and 3 years, respectively. Six (5.0%) cervical stent grafts showed endoleak; however, all these cases were successfully treated by additional endovascular repair. CONCLUSION Aortic arch repair with branched open stent grafting is an effective technique with satisfactory early results. In midterm analysis, cervical branch events were acceptably rare and controllable. This technique could be an attractive alternative to conventional total arch replacement.

The efficacy and short-term results of hybrid thoracic endovascular repair into the ascending aorta for aortic arch pathologies.

OBJECTIVES Conventional total aortic arch repair is a high-risk procedure, particularly for high-risk patients. Although endovascular treatment of aortic arch aneurysm is a recently induced procedure, only a few cases are indicated and outcomes are questionable. Here, we report on the early and short-term results of our surgical procedure, i.e. hybrid arch repair with supra-aortic debranching and endografting into the ascending aorta. METHODS Of the 514 patients who underwent arch repairs from 1997 to March 2012, 40 (28 males; mean age 74.4 years) were high-risk patients for whom hybrid arch repair of the ascending aortic landing zone was performed. Aortic pathologies included 31 degenerative aneurysms (including two ruptures), three type A dissections and four type B dissections. We performed supra-aortic debranching from the ascending aorta and endografting into the ascending aorta in 28 patients (including 10 patients with graft replacements and 3 patients with banding of the ascending aorta). For the 12 patients with an ascending aorta diameter of <36 mm, the chimney graft technique into the innominate artery was performed. RESULTS The 30-day mortality rate was 3%. Postoperative complications were as follows: stroke (0 patient), haemodialysis (1), prolonged mechanical ventilation (2) and spinal cord ischaemia (1). There were one early type I and two type II endoleaks. The mean follow-up duration was 15.5 months, during which freedom from aorta-related death and aortic events were 91 and 89% at 3 years. CONCLUSIONS We achieved satisfactory early and short-term results with hybrid arch repair into the ascending aorta. Our findings suggest that hybrid repair into the ascending aorta may be a viable option for high-risk patients with aortic arch pathologies.

Aortic Remodeling as a Prognostic Factor for Late Aortic Events After Thoracic Endovascular Aortic Repair in Type B Aortic Dissection With Patent False Lumen

Purpose: To assess the significance of aortic remodeling in the prevention of the late aortic events after thoracic endovascular aortic repair (TEVAR) for aortic dissection. Methods: The study involved 52 patients (41 men; mean age was 59.7±13.3 years) with type B aortic dissections and patent false lumens treated with TEVAR between 2004 and 2011. Of the 52 patients, 18 were treated in the acute phase for rupture (n=1), malperfusion (n=10), aortic diameter over 40 mm at onset (n=3), and rapid enlargement of the false lumen (n=4). In the chronic setting, the indications for TEVAR were rupture (n=1), malperfusion (n=2), aortic diameter >50 mm (n=18), and rapid enlargement of the false lumen (n=13). Aortic remodeling was evaluated at 6 months postoperatively, and risk factors for late aortic events were evaluated in multivariate analysis using aortic remodeling and other pre-, peri-, and postoperative factors. Results: Over a mean 36.0±18.9 months, 19 aortic events were documented: enlargement of the false lumen (n=4), type I endoleak (n=2), and erosion at the stent-graft edges (n=13). Multivariate analysis revealed that failure to achieve aortic remodeling at 6 months postoperatively was the only significant risk factor for late aortic events (hazard ratio 0.20, p=0.037). Patients with aortic remodeling had a higher rate of freedom from aortic events compared with those without aortic remodeling (100% vs. 81.5% at 1 year and 79.3% vs. 48.4% at 3 years, respectively). Conclusion: Aortic remodeling after TEVAR is a significant prognostic factor for better long-term results for type B aortic dissection.

Hydrodynamically stable adhesion of endothelial cells onto a polypropylene hollow fiber membrane by modification with adhesive protein.

The effect on the adhesion of endothelial cells of immobilization of adhesion proteins onto a microporous polypropylene hollow fiber membrane for a conventional artificial lung was investigated with the aim of constructing a hybrid artificial lung bearing endothelial cells on the modified membrane. The membrane was modified by adsorption or covalent bonding of adhesion proteins of fibronectin, gelatin, or Pronectin. The density of adherent cells on the membrane modified by adsorption of or covalent bonding with fibronectin reached 1 × 105 cells/cm2 after 1 day of incubation, which corresponds to the confluent cell density in a conventional culture dish, while the cell densities on the membranes modifieds with gelatin and Pronectin were 1–5 × 104 cells/cm2 and 0.5–1 × 104 cells/cm2, respectively. The loading of hydrodynamic shear force (0.23 N/m2) for 30 min to the membranes bearing endothelial cells had little effect on the density of adhered cells. The membrane covalently bonded with fibronectin could well maintain a high cell density even after the loading of a higher shear force of 1.15 N/m2 for 180 min, however, at this level of shear force 49% of adhered cells on the fibronectin-adsorbed membrane were lost after 30 min. A partial cardiopulmonary bypass in rats employing the hybrid artificial lung model composed of a polypropylene hollow fiber membrane covalently bonded with fibronectin and endothelial cell adhesion showed the inhibition of tumor necrosis factor-Α release and an increase in IL-10 concentration in the circulating blood compared with that employing an artificial lung without cells. Long-term partial cardiopulmonary bypass employing the hybrid artificial lung model should be studied further.

The National Cardiovascular Center electrohydraulic total artificial heart and ventricular assist device systems: current status of development.

Electrohydraulic total artificial heart (EHTAH) and electrohydraulic ventricular assist device (EHVAD) systems have been developed in our institute. The EHTAH system comprises a pumping unit consisting of blood pumps and an actuator, as well as an electronic unit consisting of an internal controller, internal and external batteries, and transcutaneous energy transfer (TET) and optical telemetry (TOT) subunits. The actuator, placed outside the pericardial space, reciprocates and delivers hydraulic silicone oil to the alternate blood pumps through a pair of flexible oil conduits. The pumping unit with an external controller was implanted in 10 calves as small as 55 kg. Two animals survived for more than 12 weeks in a good general condition. The assumed cardiac output ranged between 6 and 10 L/min, the power consumption was 12–18 W, and the energy efficiency was estimated to be 9–11%. Initial implantation of subtotal system including electronic units was further conducted in another calf weighing 73 kg. It survived for 3 days with a completely tether free system. The EHVAD system is developed by using the left blood pump and the actuator of the EHTAH, which were packaged in a compact metal casing with a compliance chamber. In vitro testing demonstrated maximum output more than 9 L/min and more than 13% maximum efficiency. The initial animal testing lasted for 25 days. These results indicate that our EHTAH and EHVAD have the potential to be totally implantable systems.

Emergency Operation for Spontaneous Coronary Artery Dissection in Young Female

Emergency coronary artery bypass grafting using a composite graft of the right internal thoracic artery and the radial artery was successfully performed for impending myocardial infarction secondary to spontaneous dissection of the right coronary artery in a 46-year-old woman. As spontaneous coronary artery dissection frequently presents as myocardial infarction or sudden death, timely diagnosis and intervention are required.