Comparison of Outcomes in DeBakey Type AI Versus AII Aortic Dissection.

The DeBakey classification divides type A acute aortic dissection (AAD) into type I and type II; the latter limited to the ascending aorta. We endeavored to examine differences in DeBakey groups in a contemporary registry. We divided 1,872 patients with noniatrogenic AAD from the International Registry of Acute Aortic Dissection into type I (n = 1691, 90.3%) and type II (n = 181, 9.7%). Patients with type II AAD were older. On presentation, patients with type I AAD reported more back and abdominal pain and were more likely to have pulse deficit. Intramural hematoma was more frequent in type II AAD. Most patients with both types were treated surgically. Lower rates of renal failure, coma, mesenteric and limb ischemia were noted in those with type II AAD. In-hospital death was less frequent (16.6% vs 22.5%) after type II AAD, a trend that did not reach significance. There was no difference in the incidence of new dissection, rapid aortic growth, late aortic intervention or survival at 5 years. In conclusion, AAD limited to the ascending aorta (DeBakey type II) appears to be associated with improved clinical outcomes compared with dissection that extend to the aortic arch or beyond. Although fewer dissection-related complications were noted in patients presenting with type II AAD, as was a trend toward reduced in-hospital mortality, 5-year survival and descending aortic sequelae are not reduced in this contemporary report from International Registry of Acute Aortic Dissection.

Randomized comparison of cold blood and cold crystalloid renal perfusion for renal protection during thoracoabdominal aortic aneurysm repair.

OBJECTIVE: More effective adjuncts are needed to reduce the incidence of acute renal injury after thoracoabdominal aortic aneurysm (TAAA) repair. The purpose of this randomized trial was to determine whether renal perfusion with cold blood provides better protection against renal ischemia than perfusion with cold crystalloid in patients undergoing TAAA repair with left heart bypass. METHODS: One hundred seventy-two patients were enrolled. Strict inclusion criteria were used, including planned Crawford extent II or III TAAA repair with left heart bypass. The patients were randomly assigned to receive intermittent renal perfusion with either 4 degrees C lactated Ringer's solution (n = 86) or 4 degrees C blood (n = 86). Renal complications within 10 days of operation were stratified by renal dysfunction score (RDS). Postoperative changes in the levels of five urinary biomarkers-retinol binding protein, alpha-1 microglobulin, microalbumin, N-acetyl-beta-D-glucosaminidase, and intestinal alkaline phosphatase-were compared to assess potential differences in subclinical renal injury. RESULTS: Although total ischemic times were longer in the cold blood group, unprotected ischemic times were similar between the two groups. Twenty-seven patients in the cold blood group (31%) and 21 patients in the cold crystalloid group (24%) had peak RDS >or=2 (serum creatinine >50% above baseline; P = .4). There were no differences between the cold blood and cold crystalloid groups in the incidence of early death (7/86 [8%] vs 5/86 [6%], respectively; P = .8) or renal failure requiring hemodialysis (3/86 [3%] in both groups). Changes in renal biomarker levels were also similar in the two groups. Spinal cord deficits developed in 5 patients in the cold blood group (6%); there were no such deficits in the cold crystalloid group (P = .06). CONCLUSION: Cold renal perfusion during TAAA repair provides effective protection against renal injury. Using cold blood instead of cold crystalloid does not enhance renal protection.

Nerve and conduction tissue injury caused by contact with BioGlue.

BACKGROUND: BioGlue-a surgical adhesive composed of bovine albumin and glutaraldehyde-is commonly used in cardiovascular operations. The objectives of this study were to determine whether BioGlue injures nerves and cardiac conduction tissues, and whether a water-soluble gel barrier protects against such injury. MATERIALS AND METHODS: In 18 pigs, diaphragmatic excursion during direct phrenic nerve stimulation was measured at baseline and at 3 and 30 min after nerve exposure to albumin (n = 3), glutaraldehyde (n = 3), BioGlue (n = 6), or water-soluble gel followed by BioGlue (n = 6). Additionally, BioGlue was applied to the cavoatrial junction overlying the sinoatrial node (SAN), either alone (n = 12) or after application of gel (n = 6). RESULTS: Mean diaphragmatic excursions in the BioGlue and glutaraldehyde groups were lower at 3 min and 30 min than in the albumin group (P < 0.05). Mean excursions in the gel group were similar to those of the albumin group (P = 0.9). Five BioGlue pigs (83%) and one gel pig (17%) had diaphragmatic paralysis by 30 min (P < 0.05 and P = 0.3 versus albumin, respectively). Coagulation necrosis extended into the myocardium at the cavoatrial junction in all 12 BioGlue pigs but only two gel pigs (33%, P < 0.01). Two BioGlue pigs (17%), but no gel pigs, had focal SAN degeneration and persistent bradycardia (P < 0.01). CONCLUSIONS: BioGlue causes acute nerve injury and myocardial necrosis that can lead to SAN damage. A water-soluble gel barrier is protective.

Transcutaneous near-infrared spectroscopy for detection of regional spinal ischemia during intercostal artery ligation: preliminary experimental results.

OBJECTIVE: Real-time information about regional spinal cord ischemia can guide intraoperative management and reduce the risk of paraplegia after thoracic aortic surgery. We hypothesized that near-infrared spectroscopy could provide such information during intercostal and lumbar artery ligation in pigs. METHODS: Transcutaneous near-infrared spectroscopic sensors were placed in the midline over the upper and lower thoracic vertebrae of 4 progressively larger pigs (weight range 21-70 kg). After the entire aorta was exposed, segmental arteries from T6 through L1 were sequentially ligated while regional oxygen saturation was monitored. Decreases in regional oxygen saturation were calculated as percentage changes from baseline. The degrees of ischemia in the upper and lower spinal cord were compared histopathologically. RESULTS: Baseline regional oxygen saturations were similar in the upper (68.8% +/- 9.0%) and lower (68.0% +/- 11.5%, P = .82) cord. After ligation, however, regional oxygen saturation levels were significantly lower in the lower cord (41.3% +/- 10.1%) than in the upper cord (64.8% +/- 9.3%, P = .037). The regional oxygen saturation had decreased by 39.0% +/- 11.5% in the lower cord but only by 6.3% +/- 7.6% in the upper cord (P = .026). This difference was confirmed microscopically: upper-cord sections had fewer ischemic neurons (8.8 +/- 9.4) than did lower-cord sections (21.3 +/- 13.6, P = .002). CONCLUSION: Intraoperative spinal cord ischemia was detectable with near-infrared spectroscopy in pigs weighing as much as 70 kg. The potential utility of this technique in patients undergoing thoracic aortic surgery warrants investigation.

The reversed elephant trunk technique used for treatment of complex aneurysms of the entire thoracic aorta.

OBJECTIVE: A preferred technique for the staged treatment of patients with aneurysms involving the entire thoracic aorta is the elephant trunk technique, with replacement of the proximal (ascending and transverse aortic arch) aorta as the initial procedure. Some patients, however, need to have the distal aortic segments (descending and thoracoabdominal aorta) addressed during the first operation. We evaluated outcomes in a series of patients who underwent distal aortic replacement first using the reversed elephant trunk technique. METHODS: Thirty-eight patients underwent first-stage graft repair of the descending thoracic (n = 3) or thoracoabdominal (n = 35) aorta using the reversed elephant trunk technique. Twelve patients (32%) ultimately underwent second-stage aortic arch replacement after a mean interval of 3.9 months (range, 1.6-14 months). RESULTS: The operative mortality for the initial procedure was 16% (6/38 patients). One patient had a stroke (3%) and 1 patient developed paraparesis (3%). In the interval between the 2 procedures, there were 4 late deaths (4/32; 13%), 1 due to respiratory failure and 3 due to unknown causes. After the 12 completion procedures, there was 1 in-hospital death (8%) and there were no strokes. Five-year survival for the overall group was 51.3 +/- 10.8%. CONCLUSIONS: Surgical treatment of aneurysms involving the entire thoracic aorta remains challenging and is associated with substantial morbidity and mortality. The reversed elephant trunk technique facilitates staged repair in patients who require distal aortic replacement during the first operation.

The threat of adhesive embolization: BioGlue leaks through needle holes in aortic tissue and prosthetic grafts.

BACKGROUND: BioGlue Surgical Adhesive (CryoLife, Inc, Kennesaw, GA) is used to reinforce anastomoses during cardiovascular operations. Previous reports have raised concerns that adhesives may leak through suture-line needle holes and that resulting intraluminal glue may embolize. The purpose of this study was to determine if BioGlue leaks through anastomotic needle holes in aortic tissue and two common prosthetic graft materials. METHODS: Polypropylene suture was used to create end-to-end anastomoses in gelatin-sealed woven polyester grafts (n = 45), expanded polytetrafluoroethylene (ePTFE) grafts (n = 45), and fresh porcine aortas (n = 45). An additional 45 anastomoses were created in ePTFE grafts using ePTFE sutures. The outer surface of each anastomosis was covered with BioGlue. Anastomoses underwent inspection with direct magnification or histology. RESULTS: BioGlue leaked through needle holes and into the lumen in 10% of anastomoses (18 of 180). Leaks were significantly more common in fresh aorta (10 of 45, 22%) than in prosthetic grafts (8 of 135, 6%; p = 0.003). Suture size did not significantly affect the incidence of leak. The use of ePTFE sutures did not eliminate BioGlue leakage. Prosthetic graft leaks created discreet round adhesive particles. In contrast, aortic tissue leaks resulted in thin, friable flakes of glue extending along the intimal surface. Aortic histology confirmed that BioGlue reached the vessel lumen via the suture channels. CONCLUSIONS: BioGlue leaked through the needle holes in fresh aortic tissue and prosthetic grafts. Intraluminal adhesive particles were easily dislodged, supporting concerns regarding embolization. The potential for adhesive embolization should be a factor when considering the relative risks and benefits of using BioGlue.

Matrix metalloproteinases in ascending aortic aneurysms: bicuspid versus trileaflet aortic valves.

BACKGROUND: Abnormal matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) expression contributes to the development of abdominal aortic aneurysms. Recent data suggest that MMP-2 and MMP-9 may also play a role in thoracic aortic disease. We sought to determine (1) whether ascending aortic aneurysms are associated with increased MMP expression and (2) whether aortic inflammation and MMP expression differ between patients with congenital bicuspid aortic valves (BAVs) and those with trileaflet aortic valves (TAVs). MATERIALS AND METHODS: Samples of ascending aortic aneurysms were obtained from 29 patients; 14 patients had BAVs and 15 had TAVs. Control ascending aorta was obtained from 14 organ donors or heart transplant recipients. Aortic histology and immunohistochemistry were performed to evaluate elastin degradation, inflammatory changes, and MMP-2 and MMP-9 expression. Aortic levels of MMP-2, MMP-9, TIMP-1, and TIMP-2 were measured using ELISA. RESULTS: Aneurysms in the TAV patients exhibited marked inflammation, high CD68 expression, diminished elastin content, increased MMP-9 expression, and normal MMP-2 levels. In contrast, BAV aneurysms were characterized by a relative lack of inflammation, preservation of elastin content, normal MMP-9 levels, and elevated MMP-2 expression. TIMP-1 and TIMP-2 levels were not significantly different among the three groups. CONCLUSIONS: Ascending aortic aneurysms exhibited increased MMP expression. The pattern of MMP expression and the degree of inflammation, however, differed between aneurysms associated with BAVs and those with TAVs. Variations in the molecular mechanisms underlying different types of thoracic aortic aneurysms warrant further investigation.

HIV-based vectors and angiogenesis following rabbit hindlimb ischemia.

BACKGROUND: Numerous medical and surgical options exist for the treatment of vessel ischemia, which some patients fail or cannot tolerate. These investigations were designed to determine the effects of lentiviral-delivered vascular endothelial-derived growth factor (VEGF) and angiopoietin-2 (Ang-2) on collateralization in a rabbit model of hindlimb ischemia. MATERIALS AND METHODS: Self-inactivating human immunodeficiency virus (HIV)-based vectors were constructed encoding VEGF or Ang-2, co-transfected with vesicular stomatitis virus glycoprotein (VSV G) into 293T cells, and vector supernatants (1 x 10(8) IU/ml after concentration) were harvested. New Zealand white rabbits had ligation of either the right or left external iliac artery and excision of the ipsilateral femoral artery. Ten days later, empty, VEGF, or VEGF+Ang-2 vector supernatant was injected intramuscularly (IM) into the ipsilateral thigh. Ankle systolic blood pressure (SBP) ratios were recorded and venous blood samples collected on postoperative days (POD) 10, 25, and 40. On POD 40, run-off angiography was performed to measure vessel collateralization. Capillary density was determined by thin sectioning of muscle. RESULTS: A significant increase was noted in SBP in the VEGF-treated animals over time. Capillary density was not elevated despite significantly increased large vessel collateralization in rabbits receiving VEGF, which was counteracted by Ang-2. Antibodies against vector components were detected in exposed serum. CONCLUSIONS: Arterial collateralization and SBP increased significantly following VEGF vector administration, which was reversed by the Ang-2 vector. Development of antibody against VSV G can limit repeated injections of vector. Future experiments will involve the addition of other pro-angiogenic factors, repeated vector administration, and alternative routes of vector delivery.

Left heart bypass during descending thoracic aortic aneurysm repair does not reduce the incidence of paraplegia.

BACKGROUND: The preferred technique for spinal cord protection during surgical repair of descending thoracic aortic aneurysms (DTAAs) remains controversial. The purpose of this retrospective analysis was to determine if the use of left heart bypass (LHB) reduced the incidence of paraplegia in patients who underwent DTAA repair. METHODS: Over a 15-year period 387 consecutive patients underwent surgical repair of DTAAs using either the "clamp-and-sew" technique (341 patients, 88.1%) or distal aortic perfusion via a LHB circuit (46 patients, 11.9%). Data regarding patient characteristics, operative variables, and outcomes were retrieved from a prospectively maintained database. The impact of LHB on the frequency of paraplegia was determined using univariate and propensity score analyses. RESULTS: There were 17 operative deaths (4.4%) including 11 patients (2.8%) who died within 30 days. Paraplegia occurred in 10 patients (2.6%). On univariate analysis increasing age (p = 0.03), increasing aortic clamp time (p < 0.001), increasing red blood cell transfusion requirements (p = 0.01), and acute dissection (p = 0.03) were associated with increased incidence of paraplegia. Patients who received LHB had a similar incidence of paraplegia (2/46, 4%) compared with those treated without LHB (8/341, 2.3%; p = 0.3). Both matching and stratification propensity score analyses confirmed that LHB was not associated with reduced risk of paraplegia. CONCLUSIONS: On retrospective analysis the use of LHB during DTAA repair did not reduce the incidence of spinal cord injury. The "clamp-and-sew" technique remains an appropriate approach to DTAA repair.

An effective strategy for optimizing hemostasis following aortic root replacementt

For patients undergoing aortic root replacement with a prosthetic composite valve graft, bleeding from the annular and coronary artery suture lines remains problematic. The purpose of this article is to describe our current strategy for optimizing hemostatis during composite valve graft placement, which employs several recent modifications, including a double-layered annular suture line.

Estimating group mortality and paraplegia rates after thoracoabdominal aortic aneurysm repair.

BACKGROUND: Most clinical studies regarding thoracoabdominal aortic aneurysm (TAAA) surgery are retrospective comparisons involving heterogeneous groups of patients. Risk models that evaluate susceptibility bias enhance interpretation of these intergroup comparisons. The purpose of this analysis was to derive group risk models for mortality and paraplegia after TAAA repair. METHODS: Data regarding 1,220 consecutive patients undergoing TAAA repair were analyzed via multiple logistic regression with stepwise model selection. Categorical preoperative risk factors that predicted 30-day mortality and paraplegia were used to develop risk models. RESULTS: Fifty-eight patients (4.8%) died within 30 days and 56 patients (4.6%) developed paraplegia or paraparesis. Predictors of mortality were rupture, renal insufficiency, symptomatic aneurysms, and Crawford extent II repairs. Extent of repair and acute presentation were predictors of paraplegia. The derived risk models estimated mortality and paraplegia rates that correlated well with actual frequencies reported in other contemporary series (regression slopes = 0.87 and 1.06, respectively). CONCLUSIONS: The derived risk models accurately estimate paraplegia and mortality rates in groups of patients. Prospective model validation will be required to confirm their accuracy.

Tracheal erosion by an innominate artery graft: presentation and surgical repair.

This report illustrates the presentation, diagnosis, and successful surgical management of a unique case involving erosion of a prosthetic innominate artery graft into the trachea.

Thoracoabdominal aortic aneurysm repair: review and update of current strategies.

BACKGROUND: Surgical repair of thoracoabdominal aortic aneurysms remains a technically challenging operation that requires a multimodality approach to preventing ischemic complications. The purpose of this report is to update our experience and highlight our current clinical strategies. METHODS: Between January 1, 1986 and December 31, 2001, 1,773 patients underwent thoracoabdominal aortic aneurysm repair. The majority of these patients (1,153, 65%) required Crawford extent I or II repairs. Segmental intercostal or lumbar arteries were reattached in 1,082 patients (61%); left heart bypass was used in 686 patients (38.7%), and 173 patients (9.8%) had cerebrospinal fluid drainage. RESULTS: The 30-day survival rate was 94.3% (1,672 patients). Postoperative complications included renal failure requiring hemodialysis in 105 patients (5.9%) and paraplegia or paraparesis in 79 patients (4.5%). Actuarial 5-year survival was 73.5% +/- 1.6%. CONCLUSIONS: This clinical experience demonstrates that current technical strategies enable patients to undergo thoracoabdominal aortic aneurysm repair with excellent early survival and acceptable morbidity.

Autotransplantation of the heart for primary cardiac malignancy: development and surgical technique.

Primary cardiac malignancy presents an unusual and difficult surgical challenge. Malignant tumors of the left atrium have proved problematic due to their posterior location and difficulty of surgical exposure. The technique of cardiac explantation, ex vivo resection and cardiac reconstruction, and reimplantation--the cardiac autotransplantation procedure--was developed to solve this anatomic problem. Herein, we discuss the development of this approach and describe the surgical technique.

Relapse of thrombotic thrombocytopenic purpura associated with decreased VWF cleaving activity.

Thrombotic thrombocytopenic purpura (TTP) is an uncommon syndrome characterized by reversible, systemic aggregation of platelets in the microcirculation and disseminated microvascular thrombosis. Surgery may precipitate TTP and has been associated with relapse in some patients. However, relapse of this life-threatening disorder is unpredictable. We report a patient with an antecedent history of TTP who experienced a relapse after elective cardiac surgery. In this case, decreased von Willebrand factor (vWF)-cleaving metalloproteinase activity and an inhibitor of this endogenous enzyme were demonstrated preoperatively. These findings suggest that decreased vWF-cleaving metalloproteinase activity and/or the presence of its inhibitor may predict an increased risk for surgical-associated relapse of TTP.

Renal perfusion during thoracoabdominal aortic operations: cold crystalloid is superior to normothermic blood.

BACKGROUND: Renal failure remains a common complication of thoracoabdominal aortic aneurysm repair. The purpose of this randomized clinical trial was to compare two methods of selective renal perfusion--cold crystalloid perfusion versus normothermic blood perfusion--and determine which technique provides the best kidney protection during thoracoabdominal aortic aneurysm repair. METHODS: Thirty randomized patients undergoing Crawford extent II thoracoabdominal aortic aneurysm repair with left heart bypass had renal artery perfusion with either 4 degrees C Ringer's lactate solution (14 patients) or normothermic blood from the bypass circuit (16 patients). Acute renal dysfunction was defined as an elevation in serum creatinine level exceeding 50% of baseline within 10 postoperative days. RESULTS: One death occurred in each group. One patient in the blood perfusion group experienced renal failure requiring hemodialysis. Ten patients (63%) in the blood perfusion group and 3 patients (21%) in the cold crystalloid perfusion group experienced acute renal dysfunction (p = 0.03). Multivariable analysis confirmed that the use of cold crystalloid perfusion was independently protective against acute renal dysfunction (p = 0.02; odds ratio, 0.133). CONCLUSIONS: When using left heart bypass during repair of extensive thoracoabdominal aortic aneurysms, selective cold crystalloid perfusion offers superior renal protection when compared with conventional normothermic blood perfusion.