The removal of all proximal aneurysmal aortic tissue does not affect anastomotic degeneration after open juxtarenal aortic aneurysm repair

ObjectiveFor the open treatment of juxtarenal aortic aneurysms (JRAAs), some argue for the removal of all proximal aneurysmal aortic tissue to prevent future degeneration, whereas others deem it unnecessary. This study sought to compare perioperative and long-term outcomes of two different approaches to treatment of JRAAs.MethodsPatients who underwent open JRAA repair from 2007 to 2015 at our institution were reviewed and stratified by operative technique: plication of the aneurysm cuff with graft sewn up to the renal arteries (PLI) vs a beveled anastomosis with left renal artery bypass (LRB). Patients who underwent additional mesenteric bypasses were excluded. Primary outcomes included death, anastomotic degeneration, and decline in renal function. Univariate and Kaplan-Meier analyses were performed.ResultsThere were 199 patients identified, 56% PLI (n = 112) and 44% LRB (n = 87). The majority were male (68%), white (89%), and smokers (58%). Mean age was 71.5 ± 8.5 years. LRB patients were more likely to have chronic kidney disease (29% vs 13%; P = .01) and larger juxtarenal diameters (median, 25 mm vs 28 mm; P = .001). LRB patients had longer postoperative length of stay (median, 8 days vs 7 days; P = .003) and longer operative times (median, 4.7 hours vs 3.7 hours; P < .001). Overall 30-day mortality was 2% (n = 4), with no difference between cohorts. There were no differences in perioperative complications except for the development of acute kidney injury, which was more common in LRB patients (47% vs 23%; P < .001). During 3-year follow-up, there was no difference in anastomotic aneurysmal degeneration or sac growth. In the long term, LRB patients were more likely to develop an occluded left renal artery (20% vs 0%; P = .004) and right renal artery stenosis (29% vs 3%; P = .002). However, neither group was more likely to have a decline in renal function (PLI, 23%; LRB, 25%; P = .84). There was no difference in 5-year mortality (P = .72).ConclusionsThe more complex technique involving LRB was not protective against long-term anastomotic degeneration, decline in renal function, or mortality. In addition, LRB led to longer length of stay and operative times, with increased risk of perioperative acute kidney injury. In an era when fewer open aortic repairs are being performed, it is reasonable to consider the PLI technique in the treatment of JRAAs, particularly in patients with baseline chronic kidney disease.     

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.     

Localization of matrix metalloproteinase 2 within the aneurysmal and normal aortic wall

BACKGROUND: Current research has shed new light on the role of matrix metalloproteinase (MMP) 2 in the development of abdominal aortic aneurysms (AAAs). MMP-2 is a major protease in the wall of small aneurysms and is produced at increased levels by smooth muscle cells derived from AAAs compared with normal controls. In vivo, MMP-2 is produced as an inactive proenzyme that is activated predominantly by the cell membrane-bound enzyme, membrane type 1 matrix metalloproteinase (MT1-MMP). This study investigated the production of the MMP-2-MT1-MMP-tissue inhibitor of metalloproteinases (TIMP) 2 system within the wall of aortic aneurysms and in age-matched control arterial tissue. METHODS: Arterial tissue from four patients with aortic aneurysms and four age-matched aortic samples was examined for the production and expression of MMP-2, TIMP-2 and MT1-MMP protein using immunohistochemistry, in situ hybridization and in situ zymography. RESULTS: All components of the MMP-2-TIMP-2-MT1-MMP enzyme system were detected in the arterial wall of both aneurysm and control samples, specifically in the medial tissue. The enzymes co-localized with medial smooth muscle cells. Gelatinolytic activity was localized to elastin fibres in normal and aneurysmal aorta. CONCLUSION: The presence of MT1-MMP within the media of arterial tissue suggests a powerful pathway for the activation of MMP-2. The localization of the MMP-2-TIMP-2-MT1-MMP enzyme system to the medial layer of the arterial wall gives support to the concept that this system may play an aetiological role in the pathogenesis of AAAs.     

Oxygen-dependent chronic obstructive pulmonary disease does not prohibit aortic aneurysm repair.

BACKGROUND: Severe oxygen-dependent chronic obstructive pulmonary disease (COPD) is considered by many to be a contraindication to open abdominal aortic aneurysm (AAA) repair. We reviewed our own experience with this patient population. METHODS: From July 1995 to March 1999, 14 consecutive patients limited by home oxygen-dependent COPD underwent elective open infrarenal AAA repair. Their medical records were reviewed. RESULTS: The mean aortic aneurysm size was 6.3 cm. The mean PaO2 = 70 mm Hg, PaCO2 = 45 mm Hg, forced expiratory volume in 1 second (FEV1) = 34% of predicted, and forced vital capacity (FVC) = 67% of predicted. All 14 patients were extubated within 24 hours, mean length of hospital stay was 5.9 days, and there were no perioperative deaths. CONCLUSIONS: Severe home oxygen-dependent COPD is not a contraindication to safe elective open AAA repair.     

Deliberate arterial hypotension does not reduce intraocular pressure in pigs.

Among the accepted advantages of general anesthesia in ophthalmic surgery is improved control of intraocular pressure (IOP). Although standard textbooks advocate deliberate arterial hypotension to facilitate intraocular surgery by reducing IOP, scientific proof of such an effect is lacking. The authors investigated effects of induced arterial hypotension on IOP in an anesthetized porcine model. Forty-two piglets were anesthetized with piritramide, were placed in the prone position, and had the anterior chamber of one eye punctured with a small Teflon cannula to measure IOP. Six pigs were used in a pilot study to establish dose-response relationships for the hypotensive agents; 36 pigs were randomly allocated to one of three groups (n = 12) to receive nitroprusside, adenosine, or isoflurane to reduce mean arterial pressure (MAP) by 50%. Measurements were made after initial stabilization of hemodynamic variables and IOP (control), when a stable MAP of 0.5x control was maintained for 10 min or longer, and after return of MAP to a posthypotensive steady state. The median of differences between time intervals was analyzed statistically for all variables. Nitroprusside and adenosine produced hyperdynamic hypotension (cardiac index increased); isoflurane-induced hypotension was hypodynamic. Control IOPs were 12.9, 12.5, and 11.1 mmHg in the nitroprusside, adenosine, and isoflurane groups, respectively. Median change in IOP during hypotension was -1.5, +1.5, and 0 mmHg in the nitroprusside, adenosine, and isoflurane groups, respectively. The IOP during adenosine-induced hypotension was significantly higher than that during either nitroprusside- or isoflurane-induced hypotension. Return of MAP to control levels was frequently associated with intraocular rebound hypertension when arterial hypotension had been induced with adenosine or nitroprusside.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hypothermic circulatory arrest does not increase the risk of ascending thoracic aortic aneurysm resection.

OBJECTIVE: The purpose of this study was to investigate the safety and efficacy of a period of deep hypothermic circulatory arrest (DHCA) during elective replacement of the ascending thoracic aorta. SUMMARY BACKGROUND DATA: DHCA has been implemented in ascending thoracic aortic aneurysm resection whenever the anatomy or pathology of the aorta or arch vessels prevents safe or adequate cross-clamping. Profound hypothermia and retrograde cerebral perfusion have been shown to be neurologically protective during ascending aortic replacement under circulatory arrest. METHODS: The authors conducted a retrospective analysis of 91 consecutive patients who underwent repair of chronic ascending thoracic aortic aneurysms from 1986 to present. The authors hypothesized that patients undergoing DHCA with or without retrograde cerebral perfusion during aneurysm repair were at no greater operative risk than patients who received aneurysm resection while on standard cardiopulmonary bypass. RESULTS: There were no significant differences in hospital mortality, stroke rate, or operative morbidity between patients repaired on DHCA when compared to those repaired on cardiopulmonary bypass. CONCLUSIONS: DHCA with or without retrograde cerebral perfusion does not result in increased morbidity or mortality during the resection of ascending thoracic aortic aneurysms. In fact, this technique may prevent damage to the arch vessels in select cases and avoid the possible complications associated with cross-clamping a friable or atherosclerotic aorta.     

Proteomic analysis of the abdominal aortic aneurysm wall

Purposes

A ruptured AAA (rAAA) is a common cause of death in males over 60 years of age, and the global mortality from rAAA exceeds 80 %. The pathological processes occurring in the wall of the developing AAA are still unclear. The potential pathophysiological mechanisms underlying aortic aneurysms have been examined by many studies using immunohistochemistry and were, therefore, targeted at specific, preselected protein antigens.

Methods

We collected samples of tissue from anterior wall of an aneurysm sac from 15 patients indicated for AAA resection (group A) during the period from 2010 to 2011. These samples were subjected to a proteomic analysis. In addition, we collected control samples of identical aortic tissue from 10 heart-beating deceased organ donors (group B).

Results

A total of 417 differentially expressed protein fractions were identified, 18 of which were only detected in the healthy controls, while 85 were specific for aneurysm tissue and 314 were detectable in both groups. In 175 protein fractions, the gel-derived spot volumes differed significantly between aneurismal and healthy aortic tissue.

Conclusions

We found a significant difference in the proteome of the AAA tissue and non-dilated aortic tissue. We demonstrated that the AAA proteome is considerably richer and more varied than the healthy and atherosclerotic aorta. We believe that our results clearly demonstrate a completely different etiopathogenesis of atherosclerosis and aneurismal disease.     

Adventitial adipogenic degeneration is an unidentified contributor to aortic wall weakening in the abdominal aortic aneurysm

Objective

The processes driving human abdominal aortic aneurysm (AAA) progression are not fully understood. Although antiinflammatory and proteolytic strategies effectively quench aneurysm progression in preclinical models, so far all clinical interventions failed. These observations hint at an incomplete understanding of the processes involved in AAA progression and rupture. Interestingly, strong clinical and molecular associations exist between popliteal artery aneurysms (PAAs) and AAAs; however, PAAs have an extremely low propensity to rupture. We thus reasoned that differences between these aneurysms may provide clues toward (auxiliary) processes involved in AAA-related wall debilitation. A better understanding of the pathophysiologic processes driving AAA growth can contribute to pharmaceutical treatments in the future.

Lightwand intubation does not reduce the increase in intraocular pressure associated with tracheal intubation.

OBJECTIVE: To evaluate the changes in hemodynamic variables and intraocular pressure (IOP) after tracheal intubation using either lightwand or direct-vision laryngoscopy techniques. DESIGN: Prospective, randomized study. SETTING: Inpatient anesthesia at a University Anesthesia Department. PATIENTS: 50 normotensive, ASA physical status I and II patients, without ocular or cardiovascular diseases, and with a Mallampati score no greater than 2. INTERVENTIONS: After intravenous (i.v.) midazolam premedication (0.05 mg.kg-1), general anesthesia was induced with fentanyl (1 microgram.g-1) and thiopental sodium (5 mg.g-1) followed by vecuronium bromide (0.1 mg.g-1), then patients were randomly allocated to receive either the lightwand (Trachlight, n = 25) or direct-vision laryngoscopy (Laryngoscopy, n = 25) intubating techniques. General anesthesia was maintained with 1% isoflurane and 60% nitrous oxide in oxygen mixture for 5 minutes. MEASUREMENTS AND MAIN RESULTS: Baseline hemodynamic variables were recorded 10 minutes after i.v. premedication, and then every minute after tracheal intubation. Intraocular pressure measurements were performed by means of a computerized indentation tonometer after general anesthesia induction and then 1 and 5 minutes after tracheal intubation. In both groups, mean arterial blood pressure and heart rate increased from baseline, without differences between the two groups. One minute after intubation, IOP increased in both groups: the mean percentage increase was 32% in the Laryngoscopy group and 16% in the Trachlight group. However, this difference was not statistically significant. Five minutes after intubation, IOP decreased to baseline values in both groups. CONCLUSION: We conclude that in healthy patients without ocular disease, using a lightwand intubating technique does not reduce the hemodynamic responses and increase in IOP associated with tracheal intubation as compared with conventional direct-vision laryngoscopy.