Aneurysm rupture after EVAR: can the ultimate failure be predicted?

OBJECTIVES: To provide insight into the causes and timing of AAA rupture after EVAR. DESIGN: Original data regarding AAA ruptures following EVAR were collected from MEDLINE and EMBASE databases. Data were extracted systematically and patient and procedural characteristics were analyzed. RESULTS: 270 patients with AAA ruptures after EVAR were identified. Causes of rupture included endoleaks (in 160: type IA 57, type IB 31, type II 23, type III 26, type IV 0, endotension 9, unspecified 14), graft migration 41, graft disconnection 11 and infection 6. Most of the described AAA ruptures occurred within 2-3 years after EVAR. Mean initial AAA diameter was relatively large (65 mm). No abnormalities were present in 41 patients during follow-up before rupture. Structural graft failure was described in 96 and a fatal course in 119 patients. CONCLUSIONS: Focus of surveillance on the first 2-3 years after EVAR may possibly reduce the AAA rupture rate, especially in patients with increased risk of early rupture (relatively large initial AAA diameter or presence of endoleak or graft migration). Better stent-graft durability and longevity is required to further reduce the AAA rupture risk after EVAR. Complete prevention will however remain challenging since AAA rupture may occur even if no predisposing abnormalities are present.

"Cobrahead" graft for intercostal artery implantation during descending aortic replacement.

A technique for a separate sidearm graft ("cobrahead") to facilitate reattachment of intercostal arteries in descending aortic replacement is described. The technique allows for very prompt restoration of spinal cord blood flow (via a Y attachment from the arterial perfusion circuit). The technique permits a simple, quick, and fully accessible anastomosis, technically more facile than the traditional side-to-side anastomosis. None of 7 patients treated with this technique had early or late paraplegia. Preliminary computed tomographic follow-up scans confirm patency of the cobrahead graft.

Experimental confirmation of effectiveness of fenestration in acute aortic dissection.

BACKGROUND: Aortic fenestration is used clinically to treat organ ischemia in acute descending aortic dissection. However, fenestration has not been studied experimentally. This study does so using an animal model. METHODS: Descending aortic dissection was created in six dogs, with subsequent fenestration of the infrarenal aorta. Blood flow (femoral, cephalic, and renal), blood pressure (femoral and carotid), and aortic distensibility were measured at baseline, after dissection, and after fenestration. Values were compared using paired t tests. RESULTS: Baseline femoral, cephalic, and renal arterial flows were 53+/-37, 78+/-65, and 83+/-52 mL/min, respectively. Baseline femoral and carotid pressures were 82+/-13 and 81+/-11 mm Hg, respectively. After dissection, femoral, cephalic, and renal arterial flow decreased to 20+/-21 (p < 0.05), 38+/-26, and 56+/-36 mL/min, respectively. Femoral blood pressure decreased to 28+/-17 mm Hg (p < 0.05). With fenestration, femoral, cephalic, and renal flows increased to 60+/-37 (p < 0.05), 78+/-51, and 80+/-48 mL/min, respectively. Femoral blood pressure increased to 85+/-28 mm Hg (p < 0.05). Carotid pressure remained unchanged with dissection and fenestration (77+/-17 mm Hg, 82+/-17 mm Hg, respectively). Baseline aortic distensibility (21%) decreased significantly after dissection (to 1.4%, p < 0.05) and increased after fenestration (to 12%, p < 0.05). CONCLUSIONS: Experimental aortic fenestration restored blood pressure and flow to hypoperfused organs in acute descending aortic dissection. The continued clinical application of fenestration is supported.

Effect of renal insufficiency on outcome following infrarenal aortic surgery.

BACKGROUND: This study reviewed the effect of preoperative renal insufficiency on outcome following elective infrarenal aortic surgery. METHODS: The charts of 210 consecutive patients undergoing aortic surgery (occlusive disease, 15%; aneurysmal disease, 78%; or combined disease, 7%) from 1990 to 1995 were categorized into three groups based on preoperative creatinine ([Cr] group 1 Cr < 1.5, n = 171; group 2 Cr 1.5 to 1.7, n = 22; and group 3 Cr > or = 1.8, n = 17) and calculated creatinine clearance ([CrCl] CrCl > 45 mL/min, n = 162 versus CrCl < 45 mL/min, n = 48). Patients with renal artery stenosis or those who required suprarenal cross clamping or emergency procedures were excluded. Differences in postoperative intensive care unit (ICU) stay, ventilator days, dialysis dependence, morbidity, and, mortality were compared. RESULTS: Patients in groups 2 and 3 had an increased incidence of postoperative dialysis dependence (group 2 9%, group 3 8%) when compared with patients in group 1 (group 1: 0%, P < 0.05). Patients in the CrCl > 45 group had a lower mortality rate when compared with patients with a CrCl < 45 (CrCl > 45 0.6% versus CrCl < 45 8%, P <0.05) a lower incidence of dialysis (0% versus 7%, P <0.05), and a lower incidence of postoperative serum creatinine elevation from baseline (CrCl > 45 8% versus CrCl < 45 18%, P <0.05). There was no significant difference in morbidity, ICU stay, or ventilator days between the groups. Upon regression analysis, preoperative CrCl but not Cr was predictive of postoperative mortality (P <0.05). Serum Cr was more predictive than CrCl of impaired renal function postoperatively. CONCLUSIONS: Preoperative CrCl is more accurate than Cr as a predictor of postoperative mortality. Patients with preoperative CrCl < 45 mL/minute who undergo elective aortic surgery have a significant increase in postoperative cardiac-related mortality and dialysis.

Initial experience with venous stents in exertional axillary-subclavian vein thrombosis.

PURPOSE: Exertional thrombosis of the axillary and subclavian veins, also known as Paget-Schrötter syndrome, has been increasingly recognized in recent years as a cause of long-term morbidity. Recent aggressive approaches to treating Paget-Schrötter syndrome have suggested the association of early failure with residual subclavian vein stenosis. As a result, the use of endoluminal stents has been proposed as an aid to venous percutaneous transluminal angioplasty for this disorder. METHODS: This report outlines the therapy of 11 consecutive patients with Paget-Schrötter syndrome who were treated at our institution between October, 1992, and December, 1995. Stents were placed when percutaneous transluminal angioplasty was unsuccessful at achieving an adequate residual lumen. RESULTS: Stents were placed after initial thrombolysis in six patients and in late follow-up in two patients. Of the six patients who had stents placed at initial thrombolysis, first-rib resection was eventually performed in four. In two patients first-rib resection was not performed, and stent fracture occurred in both. Late patency was achieved in the stents of six of the eight patients. CONCLUSIONS: Trials to evaluate stents as an adjunct to conventional therapy seem warranted. The use of stents alone without first-rib resection, however, appears to be associated with stent fracture.

Quantitative blood flow measurements with cine phase-contrast MR imaging of subjects at rest and after exercise to assess peripheral vascular disease.

OBJECTIVE: The purpose of this study was to determine whether cine phase-contrast MR volume flow measurements can identify patients with peripheral vascular disease. SUBJECTS AND METHODS: We performed MR measurements of volume blood flow in the popliteal artery of subjects at rest and after 5 min of plantar flexion exercise in 10 volunteers (mean age, 28 years old), in five patients suspected of having peripheral vascular disease (mean age, 58 years old), and in five other volunteers of a similar age (mean age, 57 years old). RESULTS: Volume blood flow at rest was similar in volunteers and in patients. Four patients who had abnormal ankle-brachial indexes had lower flow increases after exercise (2.6-fold) compared with the five older normal volunteers (4.8-fold; p < .03, t test). These flow increases correlated well with ankle-brachial indexes: r = .97. The four patients with abnormal ankle-brachial indexes had monophasic resting waveforms, whereas all other subjects had triphasic waveforms. CONCLUSION: MR volume blood flow measurement may aid in evaluating peripheral vascular disease. Studies of larger patient groups will be necessary.

Non-invasive impedance analysis: a new non-invasive test for graft surveillance.

Detection of failing grafts with early reoperation is clearly associated with better long-term patency than intervention after graft failure. Duplex ultrasonography is more accurate than ankle:brachial index for graft surveillance, but is expensive, time consuming and technically demanding. Non-invasive estimation of graft impedance is now possible. The present study was undertaken to evaluate the utility of non-invasive impedance in detecting the failing vein graft. Sixty-nine grafts in 51 patients were followed over a period of 12 months (April 1992-March 1993). High risk infrainguinal arterial vein bypass patients were entered into a graft surveillance program. Ankle:brachial index, non-invasive impedance and duplex ultrasonography were performed upon discharge, 1 month after surgery and then at 3-monthly intervals. Non-invasive impedance was measured using a mean Doppler flow signal obtained from both upper and lower ends of the graft paired with the mean pulse volume recording obtained from the distal arterial bed. The mean pulse volume recording and flow signals were digitized by discrete Fourier transform and an impedance index generated. An impedance index > or = 0.5 was considered abnormal. Impedance results were compared with ankle:brachial index, duplex ultrasonography and angiography when appropriate, and detected 28 failing and five failed grafts. Non-invasive impedance achieved a sensitivity of 91% and a specificity of 94%. Similarly, duplex ultrasonography was 91% sensitive and 97% specific, while ankle:brachial index was 58% sensitive and 94% specific. Non-invasive impedance is a simple, inexpensive and effective test which detects the failing graft and is an appropriate first-line alternative to duplex ultrasonography for postoperative graft surveillance.

Outcomes after major vascular surgery: the patients' perspective.

Surgical outcomes are traditionally defined by rates of morbidity and mortality, as well as the success with which operative objectives are met. Although quality of life after surgery has been sporadically mentioned in the literature since the turn of the century, far greater emphasis has been placed on traditional outcome measures. As the population ages and technological advances permit high-risk interventions in selected elderly patients, the assessment of outcomes with respect to quality of life has become increasingly relevant. To assess quality of life and surgical outcome, 15 patients undergoing simultaneous bilateral renal revascularization at Yale-New Haven Hospital were retrospectively studied. Fifteen charts were reviewed for data on length of hospital stay, number of days in the intensive care unit, operative morbidity, and short- and long-term results. The SF-36, a previously validated health status questionnaire, was used to survey the 11 long-term survivors. Telephone surveys were conducted by a vascular nurse. Of the 11 long-term survivors, nine patients rated their health as good to excellent (eight rated it the same or better than before surgery), eight had no or minimal physical disability, and 10 remained as involved socially as previously. The SF-36 appears to be an effective instrument for assessing postoperative quality of life. It was concluded that this group of patients was satisfied with the outcome of surgery, suggesting that major vascular surgical interventions could be undertaken in selected elderly patients without significant adverse impact on quality of life.

Splenomegaly and variceal bleeding--hemodynamic basis and treatment implications.

Splenectomy and splenic embolization have been advocated as definitive therapy in cirrhotic patients bleeding from varices. While splenomegaly is commonly associated with portal hypertension, no clear hemodynamic link between portal pressure and splenic enlargement has yet been established. In an effort to clarify the hemodynamic significance of splenomegaly in portal hypertensive patients the relationship between spleen size and portal pressure was retrospectively reviewed and the contribution of splenic inflow to portal hypertension prospectively studied. In 50 consecutive cirrhotic variceal bleeders studied angiographically, there was no correlation between spleen size and corrected sinusoidal pressure. Portal pressure was then prospectively measured before and after splenic vein clamping in 12 cirrhotic patients undergoing distal splenorenal shunt. No significant pressure drop occurred following elimination of splenic venous flow. On the basis of these data, there would appear to be no firm hemodynamic basis for splenectomy or splenic embolization alone in the unselective management of cirrhotic patients with variceal bleeding.

Peripheral vascular occlusive disease: accuracy and reliability of time-of-flight MR angiography.

PURPOSE: To determine the accuracy and reliability of magnetic resonance (MR) angiography for identification of stenosis and patent distal vessels in patients with peripheral vascular disease. MATERIALS AND METHODS: Two-dimensional time-of-flight MR angiography and conventional arteriography were performed in 22 patients. Four blinded radiologists independently graded multiple anatomic segments. RESULTS: MR angiography allowed detection of more patent vessel segments than did conventional arteriography. For detection of significant stenosis (> 75%), MR angiography had 43%-67% sensitivity and 74%-89% specificity. Discrepancies in detection of significant stenosis occurred in 39 segments for the most accurate reviewer; 27 of these discrepancies were avoidable. CONCLUSION: For detection of significant stenosis, MR angiography has low to moderate sensitivity and specificity; however, observer variability appears to be a major contributing factor to the discrepancies. Greater reviewer experience or techniques for improving reliability may improve the accuracy of MR angiography in peripheral vascular disease.

Central splanchnic venous thrombosis. Often unsuspected, usually uncomplicated.

Despite the increasingly frequent noninvasive detection of central splanchnic venous thrombosis (CSVT), its pathophysiology and clinical significance remain incompletely understood. We reviewed 50 consecutive cases of partially or totally occlusive thrombosis, primarily of the portal (60%) and splenic (40%) veins. Thirty-eight percent of patients had cancer; 26% had portal hypertension or other conditions associated with splanchnic venous stasis; and in 20%, thrombosis developed postoperatively. Angiography (89%), duplex ultrasonography (46%), CT scan (32%), and MRI (16%) were all useful diagnostic modalities. In 58% of cases, CSVT was clinically unsuspected, and 32% of patients were essentially asymptomatic. Variceal hemorrhage occurred in 30% of cases, and abdominal pain was notable in 26%. Whereas 50% of patients died < or = 6 months of diagnosis, only one of these deaths was directly attributable to CSVT; the remainder were secondary to underlying disease unrelated to the CSVT itself. CSVT, increasingly detected but often unsuspected clinically, is characterized by a self-limited and nonlethal course in the majority of patients. Death from associated disease is, however, common. The treatment and prognosis of CSVT should therefore be dictated by its clinical manifestations and the setting in which it occurs, rather than by the venous thrombosis itself.

Light reflection rheography: a simple noninvasive screening test for deep vein thrombosis.

PURPOSE: The clinical diagnosis of deep vein thrombosis (DVT) is unreliable. Contrast phlebography (CP) continues to be the gold standard, but it is invasive. Although duplex ultrasonography is an accurate, noninvasive alternative, it is expensive, technically demanding, and time-consuming. We postulated that light reflection rheography (LRR), a noninvasive method of assessing the quantity and rate of venous emptying, might be a reliable and inexpensive bedside approach to screening patients with clinically suspected DVT. METHODS: With LRR, infrared light is beamed onto the skin, and the amount of backscattered rays are detected, which indirectly measures the amount of blood present in a volume of the epidermis beneath the LRR probe. Applied to the calf muscle pump, LRR can provide a noninvasive method of assessing blood volume changes in the sample area of skin, in response to venous hemodynamic changes in the lower limb. RESULTS: Sixty-nine limbs in 61 patients undergoing CP for clinically suspected DVT over a period of 12 months also underwent LRR, either just before or within 24 hours of undergoing phlebography. The criteria for diagnosing DVT on CP were presence of filling defect or nonfilling of a venous segment. The result of LRR was considered positive for DVT if the rate of venous emptying was 0.35 or less. With these criteria a sensitivity of 96.4% and specificity of 82.9 were obtained. This resulted in a positive predictive value of 79% and a negative predictive value of 97.1%. CONCLUSIONS: LRR is a simple, inexpensive, and noninvasive bedside test that takes 10 minutes to perform. It is highly sensitive with a high negative predictive value, detecting most cases of DVT, reliably ruling out DVT, and eliminating the need for more time-consuming and costly studies. Therefore it seems to be an appropriate screening test in patients with clinically suspected DVT.

Selective shunts in selected older cirrhotic patients with variceal hemorrhage.

Whereas portal systemic shunts pose significant problems in many patients, they have long been thought to have particular risks when undertaken in older cirrhotic patients, with devastating encephalopathy reportedly common in older patients undergoing nonselective shunt surgery. With advances in anesthesia management and perioperative monitoring and the advent of selective shunting, we postulated that both the operative and long-term outcomes might be improved. In this context, we reviewed our recent experience with selective shunts [distal splenorenal (DSRS) and small-diameter interposition portacaval grafts (IPCG)] in patients over the age of 60 years with variceal bleeding. Nineteen consecutive cirrhotic patients over 60 years of age undergoing elective or urgent selective shunt surgery for variceal hemorrhage since 1986 were identified. Sixteen patients underwent DSRS, and 3 underwent IPCG. The etiologies of the cirrhosis were multiple, with 12 of 19 classified as Child's B or C disease. There were no operative deaths, and all but one patient returned home following the surgery. No patient has had recurrent bleeding or required further surgery for portal hypertension-related problems. Three of 19 developed encephalopathy, and 4 of 19 died of liver failure within 1 year of surgery. Of the 14 patients still alive and well (mean postoperative survival: 44 months, range: 4 to 74 months), all remain free of encephalopathy and live independently. Based on this experience, it would appear that one can anticipate satisfactory short- and long-term outcomes after selective shunt surgery in selected patients with variceal bleeding over the age of 60 years. These patients with portal hypertension should not, therefore, be rejected for shunt surgery based on age alone.

Captopril renal scintigraphy: a new standard for predicting outcome after renal revascularization.

PURPOSE: Captopril renal scintigraphy (CRS) is a nuclear medicine technique for evaluating each kidney independently for changes in glomerular filtration rate and perfusion induced by captopril-associated alterations in vascular tone. This study was undertaken to determine the role of CRS in predicting the response to renal revascularization. METHODS: The study group consisted of all patients who underwent preintervention CRS and arteriography, followed by renal revascularization performed between December 1987 and February 1992. After cessation of administration of angiotensin-converting enzyme inhibitors for 48 hours, a standard renogram was obtained, a 50 mg dose of captopril was given, and a second renogram was obtained. A captopril-induced change in the renogram was present when a normal pre-captopril renogram became abnormal after captopril administration. An abnormal baseline scan by definition cannot have a captopril-induced change. Blood pressure before revascularization was compared with blood pressure at 3 to 6 months after the procedure according to American Heart Association criteria for hypertension response. RESULTS: Fifty patients received renal revascularization by operation (28 patients) or balloon angioplasty (22 patients). Preoperative captopril-induced changes were present in 29 of the 50 patients. Among the 29 patients with captopril-induced changes, hypertension was cured or improved in 26. When captopril-induced changes were not present, only one of 21 patients improved (p < 0.00001). CONCLUSION: On the basis of these data, CRS appears to reliably predict hypertension response to revascularization in patients with renovascular disease.

Ischemic colitis: patterns and prognosis.

We identified 47 patients with nonocclusive ischemia of the large intestine over a seven-year period. The mean age at presentation was 56.2 years, with a 2:2:1 male predominance. Associated medical illnesses were diabetes (17 percent), renal failure (5 percent), and hematologic disorders (5 percent). Six patients developed ischemic colitis after aortic surgery. The mean delay in diagnosis was 1.8 days (range, three hours to 23 days). The right colon was involved in 21 patients (46 percent). Overall, 15 of 16 patients were successfully treated nonoperatively with bowel rest and antibiotics; one patient who was managed nonoperatively died. Among the 31 requiring intestinal resection, enteric continuity was reestablished in 14. Second-look laparotomy in eight patients revealed further ischemia in two (20 percent). Mortality in the operative group was 29 percent (9 of 31). No patient has developed recurrent ischemia (mean follow-up, 5.3 years). Ischemic colitis often occurs without an obvious predisposing event, may involve all segments of the large intestine, and frequently requires surgery. While its course may be self-limited, elderly and diabetic patients, as well as those developing ischemia following aortic surgery or hypotension, continue to have a poor prognosis.

Distal splenorenal shunt--premise, perspective, practice.

Despite progress in our understanding and management of patients with portal hypertension, the long-term control of variceal bleeding remains a significant challenge. With further clarification of the underlying pathophysiology and technological advances that have facilitated progress in both diagnosis and treatment, the goal of safe, selective management of patients presenting with variceal hemorrhage is closer to realization. While a variety of non-operative therapies have been advocated, shunt surgery remains the most reliable and durable method of controlling the portal hypertension and the bleeding. More than 20 years ago, Warren and Zeppa introduced the concept of selective shunting to prevent recurrent variceal hemorrhage. The distal splenorenal shunt (DSRS) was advocated as an approach that could selectively decompress the esophageal and gastric varices (resulting in effective bleeding control) while maintaining prograde portal flow (presumably leading to a lower incidence of post-shunt encephalopathy and hepatic failure). While the hemodynamic basis for the DSRS remains valid, its selectivity is neither uniform nor durable and this shunt is neither applicable nor effective in all patients bleeding from varices. It remains, however, appropriate and safe therapy in selected cirrhotic patients with variceal hemorrhage. With careful pretreatment assessment (in the context of the advances that have occurred in both operative and anesthetic management), the DSRS retains an important role in the management of patients with variceal bleeding.

Long-term experience with descending aortic dissection: the complication-specific approach.

We analyzed long-term results in 71 patients (45 men and 26 women) treated over 17 years for documented descending aortic dissection. Forty-nine patients were treated medically and 22, surgically. Actuarial survival was 65% at 1 year, 57% at 3 years, 50% at 5 years, and 28% at 10 years for the whole group. For the group treated medically, survival was 73%, 63%, 58%, and 25% at 1 year, 3 years, 5 years, and 10 years, respectively, and for the group treated surgically, 47%, 40%, and 28% at 1 year, 3 years, and 5 years, respectively. Ten (20.4%) of the 49 medically treated patients died early (5 of rupture), and 14 (28.6%) died late (8 of dissection). Five medically treated patients crossed over to surgical management for complications of dissection. Among the surgically treated patients, 6 underwent standard graft replacement of the proximal descending aorta, 8 underwent the fenestration procedure (with a standardized retroperitoneal abdominal approach), and 4 underwent the thromboexclusion operation. Specific analysis of fenestration in 14 patients (including some with persistent descending aortic dissection after replacement of the ascending aorta for dissection) found it to be safe and effective. Actuarial survival after fenestration was 77%, 77%, and 53% at 1 year, 3 years, and 5 years, respectively. Thromboexclusion was found effective, and postoperative studies confirmed thrombosis of the descending aorta with preservation of the lowest intercostal arteries. Fifteen of the 21 surviving medically treated patients agreed to return for follow-up imaging. Nine had thrombosis of the false lumen. An interesting radiographic finding was that 4 of the 15 restudied patients had a saccular aneurysm in the aorta at the level of the left subclavian artery. We recommend a complication-specific approach to the management of descending aortic dissection. Uncomplicated dissection is treated medically, whereas complicated dissection is treated surgically, with realized rupture treated by standard graft replacement, limb ischemia treated by fenestration, and enlargement or impending rupture treated by thromboexclusion.

Simplified captopril renography in diagnosis and treatment of renal artery stenosis.

To improve the diagnosis and forecast the response to surgery or renal angioplasty in patients with hypertension and renal artery stenosis, we employed a simplified captopril renography protocol in conjunction with renal arteriography in 94 clinically selected patients. Fifty hypertensive patients (group 1) with a high clinical likelihood of renovascular hypertension were evaluated using a simplified captopril renography protocol and renal angiography on the arterial side. Criteria for normal captopril renal scintigrams were established based on this original cohort and validated in an additional 44 clinically comparable patients (group 2). Renal revascularization or nephrectomy was performed in 39 patients, and success of the procedure was determined in the 34 patients for whom 3-month follow-up was available. In the 94 patients, 44 (47%) had renal artery stenosis. Simplified captopril renography was 91% sensitive and 94% specific in identifying or excluding renal artery stenosis in the combined group, with no difference in the diagnostic utility between groups 1 and 2, or in those with renal insufficiency (n = 38) or those with bilateral disease (n = 17). Scintigraphic abnormalities induced by captopril were strongly associated with cure or improvement in blood pressure control following revascularization or nephrectomy (15 of 18), while the lack of captopril-induced changes was associated with failure of such intervention (13 of 16) (p = 0.0004). We conclude that simplified captopril renography is highly sensitive and specific in the diagnosis of renal artery stenosis in a clinically selected high-risk population and that the test accurately predicts the success or failure of therapeutic intervention.