The natural history of intermediate and critical vein graft stenosis: recommendations for continued surveillance or repair.

OBJECTIVE: Duplex ultrasound surveillance (DUS) after autogenous lower extremity bypass grafting is controversial. Specific criteria mandating graft revision are not uniform. It has been suggested that grafts harboring critical stenoses undergo revision, whereas those with intermediate stenoses undergo arteriography with selective repair. We sought to define the natural history and determine the risk of graft occlusion associated with unrepaired vein graft stenoses. METHODS: We analyzed serial vascular laboratory and clinical data of 156 autogenous infrainguinal vein grafts in 142 patients. Grafts were categorized into three groups according to the first DUS-detected (index) lesion: (1) normal (peak systolic velocity [PSV] < 200 cm/s, velocity ratio [V(r)] < 2); (2) intermediate stenosis (200 cm/s < PSV < 300 cm/s, 2 < V(r) < 4); and (3) critical (PSV > 300 cm/s, V(r) > 4). Our policy was to repair grafts with critical lesions and monitor all others. The risks of stenosis progression, graft revision, and graft thrombosis for each group were compared. RESULTS: Serial DUS was normal in 100 (64%) grafts. The incidence of graft thrombosis in the normal group was 3% per year (mean follow-up, 27.5 months). Intermediate lesions developed in 32 grafts (20%) and were followed. Among these 32 grafts with intermediate stenoses, 63% progressed to critical and were revised, and 32% resolved or stabilized (mean follow-up, 26 months). Only one graft occlusion occurred in grafts with intermediate lesions subjected to serial DUS monitoring (incidence 1.5% per year, P = not significant). In the third group, 16 of 25 grafts with critical lesions were successfully revised and remain patent. In nine cases, critical lesions were not repaired, resulting in seven (78%) occlusions, all within 4 months of DUS detection. CONCLUSIONS: Serial surveillance is safe and effective for grafts with intermediate stenoses. The graft occlusion rate for such grafts with careful monitoring is no different from grafts without stenosis, and therefore, arteriography is not indicated in the absence of progression to critical stenosis. The short-term risk of graft occlusion in the presence of an unrevised critical stenosis is nearly 80%. These data have important clinical implications concerning the natural history of vein graft lesions.

Preimplant vein intimal thickness is not a predictor of bypass graft stenosis.

PURPOSE: Preimplant vein morphology has been implicated as a risk factor for subsequent vein graft failure. It is controversial whether microscopic intimal thickening in random saphenous vein biopsy specimens is associated with an increased risk of graft failure. The purpose of this study was to determine the incidence of preexisting intimal thickening in a macroscopically normal preimplant vein, and to evaluate whether preimplant vein intimal thickness was predictive of future vein graft stenosis. METHODS: As part of an ongoing protocol, samples of preimplant veins were obtained at the time of the primary leg bypass. Routine duplex surveillance identified 14 patients who required operative revision for severe graft stenosis (n = 12) or graft occlusion (n = 2). Verhoeff's staining of specimens was performed to delineate the internal elastic lamina. Morphometric analysis of preimplant vein specimens was performed. The results were compared to a control group of 13 preimplant vein specimens selected from patients whose grafts have remained patent and stenosis-free by duplex. RESULTS: Preoperative risk factors were identical between the two groups. Mean intimal thickness in all 27 specimens was measured by two blinded observers. Almost 50% of specimens exhibited marked intimal thickening (>0.08 mm). The mean preimplant intimal thickness of the stenosis group was 0.108 mm +/- 0.155 compared to 0.100 mm +/- 0.064 for the control group (P = 0.866, NS). CONCLUSION: Although grossly normal preimplant veins often exhibit prominent microscopic intimal thickening, preimplant vein intimal thickness determined from a random saphenous vein biopsy at the time of primary leg bypass is not predictive to the subsequent development of vein graft stenosis.

Understanding strategies for the treatment of ischemic steal syndrome after hemodialysis access.

The recently published guidelines of the National Kidney Foundation-Dialysis Outcome Quality Initiative have focused on improving patient outcomes and survival by providing recommendations for optimal clinical practice. These guidelines firmly endorse the establishment of autogenous hemodialysis access and recommend a 40% to 50% prevalence of autogenous fistulas among all hemodialysis patients. As surgeons strive to meet these guidelines it will be necessary to extend autogenous reconstruction to older individuals, diabetics, and patients with suitable vein only in the upper arm. These individuals are at increased risk for the development of the ischemic steal syndrome. It is paramount that surgeons who perform vascular access procedures have a firm understanding of the symptoms, diagnostic maneuvers, and treatment options for the ischemic steal syndrome after hemodialysis access procedures.

Considerations in the management of aneurysms of the superior mesenteric artery.

Aneurysms of the superior mesenteric artery (SMA) are rare, accounting for 5.5% of all splanchnic aneurysms and <0.5% of all intraabdominal aneurysms. Previous reports have characterized these aneurysms among splanchnic artery aneurysms. However, these aneurysms are quite different in terms of etiology, presentation, and treatment, and their independent consideration is warranted. We report a patient with a traumatic SMA aneurysms who was successfully treated with surgical resection and distal revascularization. We also present an alternative technique of retrograde aorto-SMA bypass using autologous vein that prevents kinking. Also included is a review of the recent literature as it pertains specifically to SMA aneurysms.

An economic appraisal of lower extremity bypass graft maintenance.

OBJECTIVE: Infrainguinal graft surveillance leads to intervention on the basis of duplex-identified stenoses. We have become increasingly concerned about the high frequency with which such revisions are required to maximize graft patency and limb salvage rates. The economic implications of these procedures have not been carefully analyzed or justified. METHODS: We retrospectively reviewed 155 consecutive autogenous infrainguinal bypass grafts performed for chronic leg ischemia in 141 patients. All patients were enrolled in a prospective surveillance program using color flow duplex imaging. Full economic appraisal (cost analysis, cost-effect analysis, and cost-benefit analysis) was performed for all graft surveillance and limb salvage-related interventions through use of standard accounting and valuation techniques. RESULTS: Mean follow-up was 27 months. Five-year assisted primary patency (72%) and limb salvage rates (91%) were calculated by means of life table analysis. A total of 61 grafts required 86 revisions. Within 1 year of implantation, 36% of the grafts required revision. During this first year, the mean cost per graft enrolled was $9417. Time intervals after the initial year demonstrated a reduced annual revision rate (6%) and cost ($1725 per graft). The mean 5-year cost of graft maintenance ($16,318) approached that of the initial bypass graft ($19,331). The sum of the initial cost of bypass graft and 5-year graft maintenance cost ($35,649) was similar to the cost of amputation ($36,273). Grafts revised for duplex-detected stenoses (n = 46), in comparison with those revised after thrombosis (n = 15), had an improved 1-year patency (93% vs 57%; P <.01), required fewer amputations (2% vs 33%; P <.01), less frequently required multiple graft revisions (P =.06), and generated fewer expenses (at 12 months after revision, $17,688 vs $45,252, P <.01). CONCLUSION: The cost associated with graft maintenance is significant, particularly within the first year, and demands consideration. Revision of a duplex-identified stenosis was significantly less costly than revision after graft thrombosis. Compared with the cost of limb amputation, limb salvage-related expenses appear to be justified.

Distal revascularization-interval ligation for maintenance of dialysis access and restoration of distal perfusion in ischemic steal syndrome.

Ischemic steal syndrome after hemodialysis access challenges the clinician to reconcile the dichotomy of maintenance of access patency and restoration of distal limb perfusion. Results from traditional procedures directed toward increasing the resistance in the fistula (eg, banding, lengthening) have yielded unreliable results and frequently eventuate in fistula thrombosis. The recently described technique of distal revascularization, interval ligation (DRIL) provides a more physiological approach. Based on several recent series, application of the technique has provided excellent resolution of ischemic symptoms and superior preservation of fistula patency.

Minimally invasive cardiac operation: adapting cardioprotective strategies.

BACKGROUND: Minimally invasive heart operation differs from traditional cardiac operations through the omission of a sternotomy, cardiopulmonary bypass, or both. Current concerns with minimally invasive operation include: operative safety, learning curve, operative times, arrest times, and adequacy of myocardial protection. While many of the protective strategies used for traditional procedures may be applied to minimally invasive cardiac operations, the safe applications of minimally invasive operations require unique techniques of myocardial protection. METHODS AND RESULTS: Omission of extracorporeal perfusion may benefit patients through attenuation of systemic inflammatory response, decrement in neurologic insults, and reduced bleeding complications. As a counterbalance, surgeons must consider long-term operative quality and level of myocardial protection provided during beating heart coronary operation. Current issues that must be addressed include: pharmacologic management, coronary collateralization and ischemic preconditioning, the utility of intraluminal coronary shunts, and technical adequacy of the anastomosis. Nonsternotomy cardiopulmonary bypass methods utilize alternative incisions and "port-access" technology, and may render more rapid patient recovery including: decreased pain, shortened hospital stay, and more rapid return to work. Altered strategies of myocardial protection in a closed chest environment must address: method of cannulation, technique of aortic occlusion, rapidity and maintenance of cardiac arrest, and cardiac de-airing techniques. CONCLUSIONS: Previous obstacles to minimally invasive cardiac operations included limitations in operative exposure, inadequate perfusion technology, and inability to provide myocardial protection. Recent advances in videoscopic visualization and evolving mechanisms of myocardial protection may justify the expanding application of minimally invasive techniques.

Video-assisted minimally invasive mitral valve surgery.

OBJECTIVE: This study was done to determine the potential benefits of minimally invasive mitral surgery performed with intraoperative video assistance. METHODS: From May 1996 until March 1997, a minithoracotomy and video assistance were used in 31 consecutive patients undergoing mitral repair (n = 20) and replacement (n = 11). Their ages ranged from 18 to 77 years (59 +/- 2.6 years; mean +/- standard error of the mean). Ejection fractions were 35% to 62% (55% +/- 1.5%). Operations were done with either antegrade/retrograde (n = 10) or antegrade (n = 19) cold blood cardioplegia and a new transthoracic crossclamp or with ventricular fibrillation (n = 2). Peripheral arterial cannulation (n = 28) and pump-assisted right atrial drainage (n = 26) were used most often. RESULTS: No hospital deaths occurred, but the 30-day mortality was 3.2%. Complications included deep venous thrombosis and a phrenic nerve palsy in one patient each. No patient had a stroke or required reoperation for bleeding. Postoperative echocardiography showed excellent valve function in all but one patient. Cardiopulmonary bypass and arrest times averaged 183 +/- 7.2 and 136 +/- 5.5 minutes, respectively. Compared with 100 patients having conventional mitral valve operations, these patients had significantly shorter hospitalization times (8.6 +/- 0.5 vs 5.1 +/- 0.9 days, p = 0.05). Moreover, 81% of the later cohort were discharged between day 3 and 5 (3.6 +/- 0.2 days). Hospital charges (decreases 27%, p = 0.05) and costs (decreases 34%, p < 0.05) were less than in conventional operations. Patient follow-up suggested minimal perioperative pain and rapid recovery. CONCLUSIONS: Early results suggest that video-assisted minimally invasive mitral operations can be done safely. These methods may benefit patients through less morbidity, earlier discharge, and lower cost.

Complex valve operations: antegrade versus retrograde cardioplegia?

BACKGROUND: Increasingly complex cardiac procedures demand optimal myocardial protective techniques during the requisite interval of aortic cross-clamping. For complex procedures in which prolonged cross-clamp times are anticipated, we favor combined antegrade and retrograde cold blood cardioplegia. Advantages include rapid arrest, uniform distribution, and an uninterrupted operation. METHODS: We retrospectively evaluated the cases of 194 consecutive patients who underwent complex cardiovascular procedures between January 1988 and October 1994. Procedures performed included valve repair and coronary artery bypass grafting (23.7%), valve replacement and coronary artery bypass grafting (19.1%), complex aortic arch and valve procedures (16.6%), valve repair only (16.5%), reoperative valve (9.8%), and multiple-valve replacements (9.3%). Cardioplegic arrest times averaged 113 +/- 38.5 minutes (range, 52 to 292 minutes). RESULTS: Postoperative left and right ventricular function was evaluated using transesophageal echocardiography. The echocardiograms revealed a 3.1% incidence of new left ventricular dysfunction and no case of right ventricular dysfunction. Of the patients evaluated, 75.7% required little (< 3 micrograms.kg-1.min-1 of dopamine hydrochloride) or no inotropic support postoperatively. The 30-day mortality rate was 3.1%, and no death was due to cardiac failure. CONCLUSIONS: We conclude that myocardial protection using a combined antegrade and retrograde cardioplegia technique permits excellent myocardial protection during complex cardiovascular procedures requiring long arrest times.