Nityanand Arya

Change in Aneurysm Diameter after Stent-Graft Repair of Ruptured Abdominal Aortic Aneurysms

Purpose: To compare the changes in aneurysm size following endovascular aneurysm repair (EVAR) for ruptured versus elective abdominal aortic aneurysms (AAA). Methods: Aneurysm sac diameter was measured from computed tomographic (CT) scans in 14 hemodynamically stable patients (14 men; mean age 74±7 years, range 60 to 83) prior to emergent stent-graft repair for ruptured AAA. The aneurysm diameter change was followed postprocedurally with serial CT and the outcomes compared to 74 AAA patients (58 men; mean age 74± 7 years, range 56 to 87) having elective EVAR in the same time period. The mean rate of sac decrease (mm/month) was calculated for each group. Results: There were 3 postoperative deaths in the ruptured AAA cohort, leaving 11 patients available for follow-up analysis (mean 16 months, range 2–49). Eight (73%) patients with ruptured AAA demonstrated significantly decreased (>5 mm) aneurysm diameters compared with 32 (43%) elective cases (p=0.07) followed a mean 20 months (range 3–51). The mean rate of sac diameter decrease was 1.50± 1.03 mm/month in the rupture group versus 0.73±0.86 mm/month in the elective group (p=0.04). Conclusions: This study suggests that ruptured AAAs treated with stent-graft experience sac regression at a higher rate compared with electively treated AAA. The reasons for these findings remain unclear.

Smoking Impairs Endothelial Function in Human Saphenous Vein in an Ex Vivo Model

The aim of this ex vivo experimental study was to assess the effect of smoking, diabetes mellitus, and hypertension on endothelial function in human saphenous vein, a commonly used conduit for coronary and peripheral arterial bypass surgery. A segment of long saphenous vein harvested during infrainguinal bypass surgery was mounted in an organ bath for isometric tension studies. Vein rings were precontracted to submaximal contraction with phenylephrine, followed by endothelium-dependent relaxation with acetylcholine. Long saphenous vein segments were collected from 26 patients, including five females, with a mean age of 66.4 years (range 48-92). Current smokers had impaired endothelium-dependent relaxation compared to ex- and nonsmokers (10.2%, n=13, vs. 32.9%, n=13; p<0.010). However, ex-smokers and nonsmokers did not have a significant difference in relaxant responses to acetylcholine (29.1%, n=8, vs. 24.6%, n=5; p=nonsignificant [ns]). Similarly, diabetic and nondiabetic patients did not show a significant difference in endothelium-dependent relaxation (23.1%, n=10, vs. 15.6%, n=16; p=ns). The relaxant responses in hypertensive and normotensive patients were not different (20.4%, n=12, vs. 22.5%, n=14; p=ns). Smoking has a deleterious effect on the endothelial function of saphenous vein, and smoking cessation may improve the long-term durability of saphenous vein used as a bypass graft in patients undergoing arterial reconstruction.

Endovascular repair of abdominal aortic aneurysm in a patient with renal transplant.

Patients with functioning renal transplant who develop abdominal aortic aneurysm can safely be treated with endovascular repair. Endovascular repair of aneurysm avoids renal ischemia associated with cross-clamping of aorta.

Retroperitoneal Repair of Abdominal Aortic Aneurysm Reduces Bowel Dysfunction

Objective: To assess the effect of intestinal manipulation and mesenteric traction on gastro-intestinal function and postoperative recovery in patients undergoing abdominal aortic aneurysm (AAA) repair. Methods: Thirty-five patients undergoing AAA repair were randomised into 3 groups. Group I (n = 11) had repair via retroperitoneal approach while Group II (n = 12) and Group III (n = 12) were repaired via transperitoneal approach with bowel packed within the peritoneal cavity or exteriorised in a bowel bag respectively. Gastric emptying was measured pre-operatively (day 0), day 1 and day 3 using paracetamol absorption test (PAT) and area under curve (PAUC) was calculated. Intestinal permeability was measured using the Lactulose-Mannitol test. Results: Aneurysm size, operation time and PAT (on day 0 and day 3) were similar in the three groups. On day 1, the PAUC was significantly higher in Group I, when compared with Group II and Group III (P = .02). Resumption of diet was also significantly earlier in Group I as compared to Group II and Group III. The intestinal permeability was significantly increased in Group II and Group III at day 1 when compared with day 0, with no significant increase in Group I. Retroperitoneal repair was also associated with significantly shorter intensive care unit (P = .04) and hospital stay (P = .047), when compared with the combined transperitoneal repair group (Group II and III). Conclusion: Retroperitoneal AAA repair minimises intestinal dysfunction and may lead to quicker patient recovery when compared to transperitoneal repair.

Retroperitoneal Approach to Abdominal Aortic Aneurysm Repair Preserves Splanchnic Perfusion as Measured by Gastric Tonometry

BACKGROUND We investigated if minimizing bowel manipulation and mesenteric traction using the retroperitoneal approach in open abdominal aortic aneurysm (AAA) repair preserves splanchnic perfusion, as measured by gastric tonometry, and reduces the systemic inflammatory response and dysfunction of the various organs. METHODS Patients undergoing elective AAA repair were randomized into three groups. Group I had repair via the retroperitoneal approach, while groups II and III were repaired via the transperitoneal approach with the bowel packed within the peritoneal cavity or exteriorized in a bowel bag, respectively. A tonometer was used to measure gastric intramucosal pH (pHi), as an indicator of splanchnic perfusion, just prior to aortic clamping, during clamping, and at 0.5, 1, 2, 4, 6, and 12 hr after clamp release. Multiorgan dysfunction syndrome (MODS) and systemic inflammatory response syndrome (SIRS) scores were calculated and systemic interleukins (IL-6 and IL-10) measured at predetermined intervals. RESULTS Thirty-four patients were successfully randomized. The gastric pHi was significantly lower in group II (n=12) and group III (n=11) compared to group I (n=11) during aortic clamping and immediately after clamp release (p<0.05). The aortic clamp time, blood loss, MODS and SIRS scores, and systemic cytokine response were similar in all three groups. When the three groups were combined, there were significant positive correlations between the operation time, aortic clamp time, and amount of blood lost and transfused with plasma IL-6 levels and MODS score on the first postoperative day. CONCLUSION The retroperitoneal approach for open AAA repair is associated with gastric tonometric evidence of better splanchnic perfusion compared to the transperitoneal approach.

Effects of antioxidants on endothelial function in human saphenous vein in an ex vivo model.

This ex vivo study is aimed at determining the beneficial effects of antioxidant agents on human saphenous vein endothelial function. Vein rings harvested during infrainguinal bypass surgery were assessed in an organ bath for endothelium-dependent relaxation, initially without and then with the addition of 10 μM manganese tetrakis benzoic acid porphyrin (MnTBAP), 0.01% N-acetylcysteine (NAC), 0.02% NAC, 10 μM vitamin C, and 100 μM vitamin C. Fifty-five vein rings from 22 patients were analyzed. MnTBAP improved the endothelium-dependent relaxation when compared with control (57.0% vs 37.8%, P < .01). Addition of 0.01% or 0.02% NAC did not improve the endothelium-dependent vasorelaxation (28.2% vs 18.6%, P = ns and 37.8% vs 29.8%, P = ns, respectively). Although 10-μM vitamin C failed to improve endothelial function (50.6% vs 37.2%, P = ns), 100-μM vitamin C significantly enhanced endothelium-dependent relaxation (66.5% vs 38.3%, P < .001). These results suggest that the addition of MnTBAP and high-dose vitamin C can improve the endothelial function of harvested saphenous vein segments in an ex vivo model.