Naoki Washiyama

Total arch replacement using aortic arch branched grafts with the aid of antegrade selective cerebral perfusion

BACKGROUND We report our clinical experience with total arch replacement using aortic arch branched graft in an attempt to determine the independent predictors of both in-hospital mortality and neurologic outcome. METHODS We studied 220 consecutive patients who underwent total arch replacement using aortic arch branched graft between May 1990 and June 1999. All operations were performed with the aid of hypothermic extracorporeal circulation, antegrade selective cerebral perfusion, and open distal anastomosis. RESULTS The overall in-hospital mortality rate was 12.7%. Multivariable analysis showed independent determinants of in-hospital mortality to be chronic renal failure, long pump time, participation in early series, and shock. Postoperative permanent neurologic dysfunction was 3.3%. On multivariable analysis, old cerebral infarct and pump time were independent determinants of permanent neurologic dysfunction. The selective cerebral perfusion time had no significant influence on in-hospital mortality or neurologic outcome. The 5-year survival rate including in-hospital deaths was 79% +/- 6%. CONCLUSIONS Selective cerebral perfusion allows increased ease of performance of total arch replacement, a complex and time-consuming procedure, and helps reduce periprocedural mortality and morbidity in patients with aortic arch aneurysm and those with acute aortic dissection.

Role of biologic glue repair of proximal aortic dissection in the development of early and midterm redissection of the aortic root

BACKGROUND Redissection of the aortic root after supracommissural aortic graft replacement with reapproximation of the layers of the dissected aortic root is relatively rare. Causes and surgical treatment of this lesion remain controversial. METHODS From January 1983 to September 2000, 130 patients had emergency operation for acute type A aortic dissection. Of them, 57 patients underwent root reconstruction using biologic glues and 4 patients (7.0%) developed redissection of the aortic root associated with moderate to severe aortic regurgitation 5 to 27 months after the initial operation. In all patients, the proximal false lumen was obliterated with infusion of gelatin-resorcinol-formaldehyde (GRF) glue or BioGlue and the aorta was reinforced with Teflon felt strip or Surgicel placed on its outside wall. RESULTS During reoperation, the noncoronary aortic sinus was found to be redissected in all patients with the dissection extending retrogradely to the aortic annulus. This resulted in aortic regurgitation with prolapse of the noncoronary cusp because the proximal suture line dehisced. Histopathology showed disappearance of the nuclei of the medial smooth muscle cells, suggesting tissue necrosis at the site of GRF glue application. The lesions were treated successfully with full root replacement using a freestyle heterograft bioprosthesis or a composite graft prosthesis. CONCLUSIONS The use of biologic glues for reapproximating the layers of the dissected aortic root is associated with a certain amount of risk of aortic wall necrosis. Therefore, care should be taken to ensure proper use of these glues. Full root replacement could be a preferable technique for treating redissection of the aortic root.

Extended total arch replacement for acute type a aortic dissection: Experience with seventy patients

OBJECTIVE We sought to report the clinical experience with extended total arch replacement for acute type A aortic dissection and to determine the factors that influence early mortality, late survival, and late reoperation. METHODS Between December 1988 and August 1998, 70 patients underwent emergency graft replacement of both the ascending aorta and the total aortic arch for acute type A aortic dissection. All operations were performed with hypothermic extracorporeal circulation, selective cerebral perfusion for cerebral protection during aortic arch repair, and open distal anastomosis. Concomitant procedures included aortic valve resuspension in 18 patients, composite graft replacement in 10 patients, and coronary artery bypass grafting in 5 patients. RESULTS The early mortality rate was 16% (11 of 70 patients). Multivariable analysis showed that renal-mesenteric ischemia and coronary artery bypass grafting were independent determinants for early death. Survival rates at 3 and 5 years postoperatively, including the early deaths, were 75% +/- 5% and 73% +/- 6%, respectively. Multivariable analysis showed that renal-mesenteric ischemia and en bloc repair were independent determinants for late death. Freedom from reoperation was 91% +/- 4% and 77% +/- 8% at 3 and 5 years, respectively. Multivariable analysis showed that anastomotic leakage was the only significant determinant for late reoperation. CONCLUSIONS Extended total arch replacement for acute type A aortic dissection could be justified in properly selected patients.

Brain protection using antegrade selective cerebral perfusion: a multicenter study

BACKGROUND To evaluate the results of antegrade selective cerebral perfusion as a method of brain protection during surgery of the thoracic aorta and to determine predictors of hospital mortality and adverse neurologic outcome. METHODS Between October 1995 and March 2002, 588 patients underwent aortic surgery with the aid of antegrade selective cerebral perfusion. There were 334 men (56.8%); the mean age was 63.7 +/- 11.8 years. One hundred sixty-two patients (27.6%) underwent urgent operation. The separated graft technique was employed to reimplant the arch vessels in 230 patients (65.3%) of the 352 requiring aortic arch replacement. Associated procedures were performed in 254 patients (43.2%). One hundred twelve patients underwent elephant trunk procedure. The mean cerebral perfusion time was 67 +/- 37 minutes. RESULTS The overall hospital mortality rate was 8.7%. A logistic regression analysis revealed urgent operation, recent central neurologic event, tamponade, unplanned coronary artery revascularization and pump time to be independent predictors of hospital mortality (p < 0.05). The permanent neurologic dysfunction rate was 3.8%. A logistic regression analysis showed tamponade to be independent predictor of permanent neurologic dysfunction (p < 0.05). The transient neurologic dysfunction rate was 5.6%. Recent central neurologic event, tamponade, coronary disease, and aortic valve replacement were indicated as independent predictors of transient neurologic dysfunction by logistic regression (p < 0.05). CONCLUSIONS In our experience the utilization of antegrade selective cerebral perfusion resulted in encouraging results in terms of hospital mortality and brain complications. Neither the extent of the replacement nor the duration of the cerebral perfusion had an impact on hospital mortality and neurologic outcome.

Usefulness of antegrade selective cerebral perfusion during aortic arch operations

BACKGROUND To evaluate the safety and usefulness of antegrade selective cerebral perfusion (SCP) during arch aneurysm or aortic dissection operations. METHODS Between January 1986 and December 2001, 330 patients underwent aortic arch repair using SCP. Operations were performed with the aid of hypothermic extracorporeal circulation, SCP, and systemic circulatory arrest in most cases. In all, 89 patients (27%) were operated on for acute aortic dissection, 77 (23%) for chronic aortic dissection, and 164 (50%) for degenerative aneurysm. Total arch replacement using a branched graft was performed in 288 patients (94%). Mean SCP time was 86.2 +/- 28.5 minutes. RESULTS The overall in-hospital mortality rate was 11.2% (falling to 3.2% in the 124 patients operated on between 1997 and 2001). Independent determinants of hospital mortality were pump time, renal/mesenteric ischemia, chronic renal failure, increasing age, period of operation, and nonuse of four-branched arch graft. The overall postoperative incidences of temporary and permanent neurologic dysfunction were 4.2% and 2.4%, respectively. There was no significant correlation between SCP time and in-hospital mortality or neurologic outcome. CONCLUSIONS Selective cerebral perfusion is a reliable technique for cerebral protection and it facilitates complex and time-consuming total arch replacement.

Impact of an aggressive surgical approach on surgical outcome in type a aortic dissection

BACKGROUND To evaluate the impact of an aggressive surgical approach on early and late outcome in type A aortic dissection. METHODS From 1983 to 2001, 240 patients underwent operation for acute (n = 138) and chronic (n = 102) type A aortic dissection. The extent of distal aortic resection included the ascending aorta in 39 (16%) patients, hemiarch (HAR) in 47 (20%), and total arch (TAR) in 154 (64%), including 19 patients who also had their descending aorta replaced (DAR). RESULTS The in-hospital mortality did not differ between TAR with or without DAR and other more conservative techniques (12.3% versus 16.3%). Actuarial survival at 10 years including in-hospital mortality was 72.4% +/- 3.3% and freedom from reoperation was 77.2% +/- 3.6% for all patients: neither was influenced by the extent of distal aortic resection or acuity of aortic dissection. Multivariate analysis revealed younger age and failure to resect the intimal tear to be independent determinants for late reoperation. However, in contrast to 22 patients who had more conservative operations, none of the patients with TAR required reoperation on the aortic arch through a sternotomy incision. CONCLUSIONS An aggressive surgical approach did not adversely influence early and late survival following type A aortic dissection; it reduced the necessity of late reoperation and facilitated distal aortic reoperation.

Late reoperation for proximal aortic and arch complications after previous composite graft replacement in Marfan patients.

BACKGROUND Marfan patients who received composite graft replacement for proximal aortic disease frequently require late reoperation. The initial surgical technique for this lesion remains controversial. METHODS Fourteen Marfan patients who received composite graft replacement for annuloaortic ectasia with or without aortic dissection required late reoperation thorough re-median sternotomy. The techniques used for an initial composite graft replacement were the original Bentall procedure in 11 patients, the Cabrol procedure in 2, and coronary button technique in 1. Reoperation was indicated for prosthesis-related complications in 10 patients, distal aortic lesion in 13, or for both lesions in 8. Reoperations were performed, on average, 8.4 years after an initial operation. Reoperative procedures included re-composite graft replacement in 1 patient, total arch replacement in 5, and re-composite graft replacement with total arch replacement in 8. RESULTS There were two in-hospital deaths (14.3%). Although pseudoaneurysms of the coronary artery or distal aorta occurred in the original Bentall or Cabrol procedures, true aneurysms of the coronary artery were noted even in the coronary button technique. Six patients required a total of eight subsequent descending or thoracoabdominal aortic replacements for an aneurysmal formation of a distal false lumen. CONCLUSIONS The coronary button technique, with a small side hole for coronary anastomosis, is the procedure of choice for annuloaortic ectasia because it reduces the risk of coronary artery-related complications. Concomitant total arch replacement may be recommended for annuloaortic ectasia with DeBakey type I aortic dissection in selected patients to avoid the risk of reoperation on the aortic arch.

Cerebral oxygenation monitoring for total arch replacement using selective cerebral perfusion

BACKGROUND This study was undertaken to verify the safety of our total arch replacement assisted by selective cerebral perfusion with respect to cerebral oxygenation. METHODS Subjects to be evaluated were selected between February 1999 and March 2000 and comprised 13 patients who underwent total arch replacement (TAR) (TAR group) and 18 patients who had undergone coronary artery bypass grafting or valve replacement (control group). They were monitored throughout the operation by two-channel near-infrared spectroscopy. Changes in intracranial oxyhemoglobin and the tissue oxygenation index were compared between the two groups. Additionally, jugular venous oxygen saturation was simultaneously measured in 10 patients from each group. Maximum changes in these variables from baseline in the TAR group were compared with those in the control group. Bilateral oxygenation differences between two hemispheres were also evaluated. RESULTS There was no incidence of postoperative cerebral infarction, and no significant difference was observed in the maximum decrease in these variables between the two groups. Bilateral oxygenation differences between the two hemispheres in the TAR group were similar to those in the control group, except for the tissue oxygenation index in the rewarming phase. CONCLUSIONS From the standpoint of cerebral oxygenation, our technique of total arch replacement was nearly as safe as an ordinary cardiac operation.

Histological changes in canine aorta 1 year after stent-graft implantation: implications for the long-term stability of device anchoring zones.

Purpose: To examine aortic histology 1 year after stent-graft implantation in a canine model as a means of assessing the durability of endograft fixation. Methods: Fourteen mongrel dogs each received 1 stent-graft and 1 bare stent placed endoluminally in the abdominal aorta. Eight animals were followed for 1 year, 3 for 4 to 8 weeks, and the remaining 3 for 24 to 48 hours. Aortic specimens were stained with hematoxylin-eosin, elastica-van Gieson, and Massons trichrome and examined with light and electron microscopy and immunohistochemistry to identify smooth muscle cells (SMC), endothelialization, aortic wall ultrastructure, and changes at the device anchoring sites. Results: No dilatation or dissection was noted at any of the device anchoring sites. The aortic media at 1 year was remarkably decreased in thickness: 891 ± 196 µm in the control tissue versus 388 ± 70 µm for the proximal stent-grafted aorta and 457 ± 148 µm for the bare-stented aortic segment. Other important histological features were reduced elastic lamellae in the stent-grafted aorta versus control (p<0.0001), increased SMC density in the stent-grafted aortic region (p<0.0001 versus control), and absence of inflammatory infiltrate. Complete neointimal covering and endothelialization of the luminal endograft surface were found. SMCs generally showed no ultrastructural features of necrosis. Conclusions: Aortic stent-grafts induce distinctive histological changes in the aortic wall at 1 year, even when implanted in a healthy aorta. Although there is considerable medial elastin loss, an increased medial SMC density, an exuberant neointima, and a general absence of perigraft inflammation suggest an ongoing process of structural restoration at the device anchoring sites.

Characterizing saccular aortic arch aneurysms from the geometry-flow dynamics relationship

Objective: Low wall shear stress (WSS) has been reported to be associated with accelerated atherosclerosis, aneurysm growth, or rupture. We evaluated the geometry of aortic arch aneurysms and their relationship with WSS by using the 4‐dimensional flow magnetic resonance imaging to better characterize the saccular aneurysms. Methods: We analyzed the geometry in 100 patients using multiplanar reconstruction of computed tomography. We evaluated WSS and vortex flow using 4‐dimensional flow magnetic resonance imaging in 16 of them, which were compared with 8 age‐matched control subjects and eight healthy young volunteers. Results: Eighty‐two patients had a saccular aneurysm, and 18 had a fusiform aneurysm. External diameter/aneurysm length ratio and sac depth/neck width ratio of the fusiform aneurysms were constant at 0.76 ± 0.18 and 0.23 ± 0.09, whereas those of saccular aneurysms, especially those involving the outer curvature, were higher and more variable. Vortex flow was always present in the aneurysms, resulting in low WSS. When the sac depth/neck width ratio was less than 0.8, peak WSS correlated inversely with luminal diameter even in the saccular aneurysms. When this ratio exceeded 0.8, which was the case only with the saccular aneurysms, such correlation no longer existed and WSS was invariably low. Conclusions: Fusiform aneurysms elongate as they dilate, and WSS is lower as the diameter is larger. Saccular aneurysms dilate without proportionate elongation, and they, especially those occupying the inner curvature, have higher and variable sac depth/neck width ratio. When this ratio exceeds 0.8, WSS is low regardless of diameter, which may explain their malignant clinical behavior.