Aortic Arch Morphology and Aortic Length in Patients with Dissection, Traumatic, and Aneurysmal Disease.

OBJECTIVES: To assess aortic arch morphology and aortic length in patients with dissection, traumatic injury, and aneurysm undergoing TEVAR, and to identify characteristics specific to different pathologies. METHOD: This was a retrospective analysis of the aortic arch morphology and aortic length of dissection, traumatic injury, and aneurysmal patients. Computed tomography imaging was evaluated of 210 patients (49 dissection, 99 traumatic injury, 62 aneurysm) enrolled in three trials that received the conformable GORE TAG thoracic endoprosthesis. The mean age of trauma patients was 43 ± 19.6 years, 57 ± 11.7 years for dissection and 72 ± 9.6 years for aneurysm patients. A standardized protocol was used to measure aortic arch diameter, length, and take-off angle and clockface orientation of branch vessels. Differences in arch anatomy and length were assessed using ANOVA and independent t tests. RESULTS: Of the 210 arches evaluated, 22% had arch vessel common trunk configurations. The aortic diameter and the distance from the left main coronary (LMC) to the left common carotid (LCC) were greater in dissection patients than in trauma or aneurysm patients (p < .001). Aortic diameter in aneurysm patients was greater compared with trauma patients (p < .05). The distances from the branch vessels to the celiac artery (CA) were greater in dissection and aneurysm patients than in trauma patients (p < .001). The take-off angle of the innominate (I), LCCA, and left subclavian (LS) were greater, between 19% and 36%, in trauma patients than in dissection and aneurysm patients (p < .001). Clockface orientation of the arch vessels varies between pathologies. CONCLUSIONS: Arch anatomy has significant morphologic differences when comparing aortic pathologies. Describing these differences in a large sample of patients is beneficial for device designs and patient selection.

Predictors of early graft failure after infrainguinal bypass surgery: a risk-adjusted analysis from the NSQIP.

INTRODUCTION AND OBJECTIVES: Infrainguinal bypass surgery (BPG) is accompanied by significant 30-day mortality and morbidity, including early graft failure. The goal of this study is to identify patient- and procedure-specific factors which predict the rate of early graft failure in contemporary practice. METHODS: Data was obtained from the private sector National Surgical Quality Improvement Program, a prospective, validated database collected between 2005 and 2008 from 211 hospitals, using primary and modifier Current Procedural Terminology codes for BPG. The primary endpoint was graft failure at 30 days. Procedural parameters, patient demographics and clinical variables were analyzed by univariate and multivariate methods. RESULTS: There were 9217 BPG procedures (limb salvage, 49%; infrapopliteal distal anastomosis, 43%; prosthetic 32%) with patient variables: age 67 ± 12 years, male 64%, diabetes 44%, dialysis 7.4%. Mortality was 2.4%, major morbidity was 17.3%, and graft failure rate was 6.3% at 30 days. Multivariate predictors of graft failure demonstrated correlation (p-value, OR) with female gender (p = 0.0054, 1.29), limb salvage indication (p < 0.0001, 1.60), infrapopliteal anastomosis (p < 0.0001, 2.15), composite graft (p = 0.0436, 1.82), current smoking (p = 0.0007, 1.36), impaired sensorium (p = 0.0075, 2.13), emergency procedure (p < 0.0001, 2.03), previous vascular procedure (p = 0.0005, 1.39), and platelets >400K (p = 0.0019, 1.49). High-risk composite constructs utilizing these significant predictive factors can identify cohorts of patients with up to a 98-fold increase in odds of early graft failure. CONCLUSIONS: These results describe common risk factors that correlate with early graft thrombosis including the unique description of its association with thrombocytosis. Additional risk factors thus identify a subset of patients who are at highest risk for early BPG failure. This data may be used to refine patient selection.

Development and validation of a Bayesian model for perioperative cardiac risk assessment in a cohort of 1,081 vascular surgical candidates.

OBJECTIVES: This study sought to develop and validate a Bayesian risk prediction model for vascular surgery candidates. BACKGROUND: Patients who require surgical treatment of peripheral vascular disease are at increased risk of perioperative cardiac morbidity and mortality. Existing prediction models tend to underestimate risk in vascular surgery candidates. METHODS: The cohort comprised 1,081 consecutive vascular surgery candidates at five medical centers. Of these, 567 patients from two centers ("training" set) were used to develop the model, and 514 patients from three centers were used to validate it ("validation" set). Risk scores were developed using logistic regression for clinical variables: advanced age (>70 years), angina, history of myocardial infarction, diabetes mellitus, history of congestive heart failure and prior coronary revascularization. A second model was developed from dipyridamole-thallium predictors of myocardial infarction (i.e., fixed and reversible myocardial defects and ST changes). Model performance was assessed by comparing observed event rates with risk estimates and by performing receiver-operating characteristic curve (ROC) analysis. RESULTS: The postoperative cardiac event rate was 8% for both sets. Prognostic accuracy (i.e., ROC area) was 74 +/- 3% (mean +/- SD) for the clinical and 81 +/- 3% for the clinical and dipyridamole-thallium models. Among the validation sets, areas were 74 +/- 9%, 72 +/- 7% and 76 +/- 5% for each center. Observed and estimated rates were comparable for both sets. By the clinical model, the observed rates were 3%, 8% and 18% for patients classified as low, moderate and high risk by clinical factors (p<0.0001). The addition of dipyridamole-thallium data reclassified >80% of the moderate risk patients into low (3%) and high (19%) risk categories (p<0.0001) but provided no stratification for patients classified as low or high risk according to the clinical model. CONCLUSIONS: Simple clinical markers, weighted according to prognostic impact, will reliably stratify risk in vascular surgery candidates referred for dipyridamole-thallium testing, thus obviating the need for the more expensive testing. Our prediction model retains its prognostic accuracy when applied to the validation sets and can reliably estimate risk in this group.

Heparin fails to suppress intimal proliferation in experimental vein grafts.

Heparin has been shown to suppress both vascular smooth muscle cell proliferation in vitro and intimal hyperplasia in animal models of arterial injury. We investigated the effect of heparin on early postoperative smooth muscle cell proliferation and intimal thickening in vein grafts placed in the rat infrarenal aorta. Experimental animals (n = 6) received subcutaneous heparin (800 units/kg with levels monitored by activated factor X assay) every 12 hours for 3 days after surgery to coincide with the known period of maximal vascular wall DNA synthesis after injury. Control animals (n = 7) received identical vein grafts but no heparin. Grafts were harvested with perfusion fixation 14 days after insertion. Tritiated thymidine autoradiography was used to derive a mitotic index in regions of interest along the grafts, and computerized planimetric measurements of intimal and medial thickness were made in the same regions. Evans blue lumenal staining at harvesting revealed confluent endothelial coverage of both experimental and control grafts. The mitotic index of the vein graft's midsection and perianastomotic regions was significantly higher (p less than 0.005) than that of the native aorta in all animals, indicating cellular proliferation within all grafts, with no differences noted between heparinized and control animals. Similarly, both groups exhibited vein graft intimal and medial thickening at the anastomoses relative to the midsection of the vein graft (p less than 0.001). Heparin, administered in the equivalent of pharmacologic clinical doses, failed to suppress cellular proliferation and intimal hyperplasia in this model of vein grafting.

The effect of halothane anesthesia on platelet aggregation in vivo: decreased deposition on polytetrafluoroethylene arterial grafts in dogs.

The technique of gamma-imaging can be used to study the deposition of 111In-labeled platelets onto synthetic arterial grafts in vivo. Recent results suggested that platelet uptake on polytetrafluoroethylene (PTFE) grafts might depend on the choice of anesthetic. To evaluate the effect of anesthesia a series of experiments was performed in seven dogs wherein each animal served as its own control. The first of paired femoral or carotid PTFE grafts was inserted with the animal under pentobarbital anesthesia, and the graft was imaged for 90 minutes. A second graft was then inserted after at least 1 hour of halothane anesthesia. The mean activity ratio (describing platelet deposition) in the grafts inserted when only pentobarbital anesthesia was used was 7.04 +/- 0.55, compared to 1.20 +/- 0.07 in the grafts inserted with halothane anesthesia (P less than 0.01). Halothane anesthesia led to significantly decreased platelet uptake on canine PTFE arterial grafts. This effect was reversible, though not immediately, with no significant difference in graft activity noted by the day following surgery.

Evidence for nongastrin-mediated somatostatin inhibition of parietal cell function.

Somatostatin (SRIF), a tetradecapeptide, has been reported to suppress gastrin release and hence inhibit acid secretion in vivo. This study was performed to determine whether SRIF has any direct effect on parietal cell (PC). Isolated gastric cells were prepared by collagenase digestion and calcium chelation of rabbit fundic mucosa. PC enrichment (75% +/- 5%) was accomplished by velocity sedimentation with an elutriator rotor. Acid, as assessed by the accumulation of 14C-aminopyrine (AP) and macromolecular (intrinsic factor [IF]) secretion were used as markers of PC function. Cells were stimulated with histamine (H) (10(-6) mol/L). SRIF (10(-10) to 10(-6) mol/L) significantly inhibited H-stimulated 14C-AP accumulation (p less than 0.05). Inhibition of H-stimulated IF release was less sensitive, occurring at 10(-8) and 10(-7) mol/L (p less than 0.05), and loss of inhibition was observed at 10(-6) mol/L (p less than 0.05). These results demonstrate a direct inhibitory action of SRIF on PC secretion. The difference in inhibitory effect on IF and proton secretion is consistent with the postulation that SRIF may function at more than one site within the PC.

Intestinal ischemia complicating abdominal aortic surgery.

A 9-year experience with 2137 patients undergoing infrarenal abdominal aortic reconstruction was reviewed to determine both the incidence of intestinal ischemia and the clinical, anatomic, and technical factors associated with this complication of aortic surgery. A total of 24 (1.1%) patients had overt intestinal ischemia, documented by reoperation or endoscopic findings. Of these, colon ischemia occurred in 19 (0.9%) and small bowel ischemia developed in 5 (0.2%) patients. The incidence after elective operation for aneurysmal or occlusive disease did not differ, but patients with ruptured aneurysms and those undergoing reoperative procedures for total graft replacement were at higher risk. Preoperative angiography was most helpful in ascertaining risk. Ligation of a patent inferior mesenteric artery was the most common (74%) feature in patients with colon ischemia. With preexisting inferior mesenteric artery occlusion, impairment of collateral circulation was attributable to superior mesenteric artery disease, dissection or retractor injury, prior colon resection, or exclusion of hypogastric perfusion. Bloody diarrhea was the most frequent postoperative symptom and colonoscopy the most reliable means of diagnosis. One half of patients with colon ischemia required resection after late recognition of perforation. All cases of small bowel ischemia were related to superior mesenteric artery disease or injury or use of suprarenal clamping. The overall mortality rate was 25% but rose to 50% if bowel resection was required. Intestinal ischemia remains an infrequent but serious complication of aortic surgery. Despite a multifactorial cause, identification of patients at increased risk can lead to operative strategies to reduce its occurrence.

Hepatic portal venous gas in diverticulitis: survival in a steroid-treated patient.

Hepatic portal venous gas (HPVG) in the adult is usually associated with bowel necrosis. Together these have an 80% mortality. However, HPVG may occur as a result of a variety of other pathologic conditions. We studied what we believe is the second known case resulting from sigmoid diverticulitis. This patient's survival was unexpected, because bowel perforation and pathologically demonstrated septic phlebitis occurred during the patient's long-term corticosteroid therapy.

Expanding surgical options using minimally invasive techniques for cardio-aortic and aortic procedures.

In an effort to minimize the morbidity and mortality of open cardio-aortic and aortic operations, which are ranked among the most extensive procedures, surgeons are attempting to use smaller minimal-access incisions, less-invasive open procedures, or more distal access sites to place aortic stented grafts by intraluminal closed methods. We review the latest trends in this rapidly evolving new field of minimally invasive surgery.

Acute arterial thrombosis of the lower extremity. Its natural history contrasted with arterial embolism.

We compared a group of 52 patients with acute lower extremity ischemia secondary to arterial thrombosis with a series of 220 patients with peripheral embolism who were seen at the Massachusetts General Hospital, Boston, from 1967 through 1980. The conditions of patients with arterial thrombosis were misdiagnosed as acute embolism at a rate of 20%. Mortality in the patients with embolism was significantly higher. While patients with acute embolism were routinely treated with embolectomy, two thirds of the patients with thrombotic occlusion required surgery during their initial hospitalization for ongoing severe ischemia. More than half of these operations were carried out as emergency procedures. Limb salvage in surgically treated patients with arterial thrombosis was inferior to that seen with embolism. Early revascularization for acute thrombosis was carried out with a 30-day patency rate of 82%. While the mortality associated with acute thrombosis was significantly lower than that seen with peripheral embolism, the risk of major amputation was 35%. There should be no reluctance to proceed with indicated vascular reconstruction in the setting of acute limb ischemia secondary to arterial thrombosis.

Percutaneous angioplasty for peripheral arterial occlusive disease. Correlates of clinical success.

We reviewed 142 percutaneous transluminal angioplasties (PTAs) in the iliac (n = 94) and femoropopliteal (n = 48) positions of 107 patients. Emphasis was placed on the ultimate clinical outcome, which was determined from a pool of clinical, hemodynamic, and angiographic data. Limb-threatening ischemia was the indication for intervention in 53% of the cases. The median follow-up interval was 17 months. Overall success was achieved in 50% of cases in both iliac and femoral positions at one year after PTA. The following factors were found to correlate with a successful clinical outcome: PTA for claudication vs limb-threatening ischemia (P less than .001); focal as opposed to diffuse stenosis or occlusion (P less than .02); immediate return of distal pulses (P less than .001); the absence of diabetes (P less than .05); and the presence of a patent outflow tract (P less than .001). Treatment results with PTA will vary widely according to the nature of the patient population and the criteria for determining success.

Noninvasive intraoperative assessment of arterial reconstruction. Experimental validation of the role of central and regional hemodynamics.

We developed an experimental model of graded arterial stenosis to emulate conditions that might be encountered immediately following arterial grafting. Noninvasive measurements of systolic BP and limb blood flow were recorded with a Doppler probe and segmental air plethysmography, respectively, under conditions of different cardiac output and local arterial resistance. These measurements were correlated with direct intra-arterial pressure recordings and flow measurements taken with an electromagnetic flowmeter. There was an excellent correlation between noninvasive and intra-arterial measurements of systolic pressure over a range of cardiac outputs and degree of arterial stenosis. Pulse volume recordings correlated with direct measurements of blood flow at high and baseline cardiac outputs, but the calibration of pulse volume amplitude varied between cuff applications in this canine model. Noninvasive intraoperative monitoring techniques can faithfully represent known physiologic responses to graded arterial stenoses, irrespective of a high cardiac output or peripheral vasodilation.

Role of endoscopy in the diagnosis of early gastric cancer.

Early gastric cancer (EGC) is characterized by tumor invasion limited to the submucosa, with or without regional lymph node involvement, and five-year survival rates in excess of 90%. Although infrequently reported in the United States, EGC represents 35% of gastric cancers in Japan. A retrospective analysis of all patients with gastric cancer (1972 through 1985) was performed to determine the frequency and most efficacious diagnostic modalities in this group of patients. Early gastric cancer was identified in 6% (17/302) of all these patients and in 28% (17/61) of patients undergoing curative resection. A review of presenting historical, physical, laboratory, radiologic, and endoscopic findings identified fiberoptic endoscopy as the most sensitive diagnostic procedure. Increased use of endoscopy in patients with persistent nonspecific gastrointestinal tract complaints may increase the number of patients seen with EGC.

Recent experience with thoracoabdominal aneurysm repair.

Thoracoabdominal aneurysm repair was carried out in 55 patients during the period from January 1978 to June 1988. Considering the volume of experience and application of a routine for preoperative and intraoperative management, the experience was divided as follows: group 1 1978 to 1985 (26 patients) and group 2 1985 to 1988 (29 patients). Clinical features of the two groups differed only in the incidence of emergency operations (group 1 [6/18, 30%] vs group 2 [2/29, 8%]). Operative mortality in elective operations improved substantially in recent experience (group 1 [50%] vs group 2 [7.4%]). Significant reductions in total operative time, operative blood loss, and total aortic cross-clamping times paralleled and, in part, explained the improvement in overall surgical results seen in group 2 patients. Spinal cord injury occurred in 7.2% of the entire cohort. Nonfatal but major complications occurred in 25% of group 2 patients, with the most common being prolonged ventilatory assistance (12%). Current results with thoracoabdominal aneurysm repair both establish its safety and help to provide guidelines in selecting patients for elective repair.

Safety and efficacy of concomitant carotid and coronary artery operations.

BACKGROUND: Controversy exists concerning the best management for patients with concurrent severe carotid and coronary artery disease. METHODS: The records of 200 consecutive patients having concurrent carotid endarterectomy and coronary artery bypass grafting from 1979 to 1993 were reviewed, and follow-up was obtained (99% complete). Of the group (77% male; mean age, 67 years), 134 (67%) had unstable angina, 130 (65%) had triple-vessel disease, and 86 (43%) had left main coronary stenosis. Preoperative investigation revealed asymptomatic bruits in 116 (58%), transient ischemia in 65 (32%), strokes in 31 (16%), and bilateral carotid disease in 44 patients (22%). Nonelective operations were required in 66 patients (33%). RESULTS: Hospital death occurred in 7 patients (3.5%), myocardial infarction in 5 (2.5%), and permanent stroke in 6 (3%). Ten-year actuarial event-free rates were as follows: death, 58%; myocardial infarction, 81%; stroke, 92%; percutaneous angioplasty, 98%; redo coronary artery grafting, 94%; and all morbidity and mortality, 56%. Significant multivariate predictors of hospital death were postoperative stroke, failure to use an internal mammary artery graft, intraoperative intraaortic balloon, and nonelective operation. Significant predictors of postoperative stroke were peripheral vascular disease and unstable angina. Significant predictors of prolonged hospital stay were postoperative stroke, advanced age, and nonelective operation. CONCLUSIONS: Concomitant carotid endarterectomy and coronary bypass grafting can be performed with acceptably low operative risk and good long-term freedom from coronary and neurologic events.

Ureteroarterial fistula: case report and review of the literature.

Ureteroarterial fistulae are rare. We report 2 cases of this clinical problem. Ureteroarterial fistulae can occur in association with prolonged ureteral stenting, radiation therapy, vascular pathology, and prior pelvic or vascular surgery. Identification of a fistula is often difficult and requires the physician to be highly alert and vigilant. Diagnostic and therapeutic options for a ureteroarterial fistula are discussed.

Regional hypothermia for prevention of spinal cord ischemic complications after thoracoabdominal aortic surgery: experience with epidural cooling.

A technique for regional hypothermic protection of spinal cord with epidural cooling during thoracoabdominal aneurysm (TAA) repair has been applied in over 100 patients. Elevation of cerebrospinal fluid pressure during the infusion is the principle technical limitation of the technique. When compared to institutional historic controls, patients treated with epidural cooling had a significant reduction in spinal cord ischemic complications. In patients treated for elective Types I, II, III TAA with epidural cooling, spinal cord complications have been reduced to the 3% range.

Regional hypothermia with epidural cooling for spinal cord protection during thoracoabdominal aneurysm repair.

Several techniques have been developed and clinically applied to reduce the spinal cord ischemia complications that follow thoracoabdominal aortic aneurysm (TAA) repair. Hypothermia as a protective adjunct is a concept that has been used throughout the evolution of cardiac and central aortic surgery. Because experimental regional hypothermic perfusion delivered directly to the epidural or intrathecal space showed protective effects against cord injury, we developed and applied a method for providing regional cord hypothermia with epidural cooling during TAA repair. This review describes the technical considerations with epidural cooling and the clinical results obtained in our experience.