The health care crisis: impact on surgery in the community hospital setting.

Hospitals and health systems across the United States are in crisis. The causes of this crisis are multiple, and they reflect the interplay among reduced operating margins, workforce issues, the technology explosion, consumerism, and leadership. They affect hospitals of every type and location. In aggregate, they profoundly influence our trifold mission of patient care, education, and research. Departments of surgery have a disproportionate effect on hospital financial viability, and therefore, surgical leaders must work with other clinical and administrative leaders to manage these issues. This article is a personal view of how this crisis has affected our community-based academic medical center, William Beaumont Hospital, Royal Oak, Mich.

Experience in the United States with intact abdominal aortic aneurysm repair.

OBJECTIVES: The purpose of this study was to determine the current outcome in the United States and to identify predictors of mortality and "bad outcome" after open, intact abdominal aortic aneurysm (AAA) repair. METHODS: In a retrospective analysis, data were obtained from the Nationwide Inpatient Sample during 1994-1996. The Nationwide Inpatient Sample is a 20% all-payer stratified sample of nonfederal United States hospitals. Patients older than 49 years were identified by the presence of primary diagnostic (441.4-intact AAA) and procedure (38.44-resection of abdominal aorta with replacement) codes of the International Classification of Diseases, Ninth Revision (ICD-9 ). In-hospital mortality rate, discharge disposition, bad outcome (death or discharge to an institution), complications (ICD-9 postoperative codes), length of stay, and charges were determined. The mortality rate and bad outcome were analyzed by the use of patient demographics (age, sex, race), patient comorbidities (ICD-9 diagnostic codes), calendar year, and hospital characteristics (size, location, teaching status) with univariate and multivariate analyses. RESULTS: We identified 16,450 intact AAAs repairs during the study years. The mean patient age was 72 +/- 7 (+/- SD) years, and most patients were male (79.7%) and white (94.6%). Most repairs were performed at large (67.3%), urban (92.5%), and nonteaching (66.7%) institutions. The in-hospital mortality rate was 4.2%, the overall complication rate was 32.4%, and 91.2% of patients were discharged home, whereas the bad outcome rate was 12.6%. The median length of stay was 8 days (mean, 10.0 +/- 8.1), and median hospital charges were $28,052 (mean, $35,681 +/- $33,006) in 1996 dollars. Multivariate analysis showed that the mortality rate (P <.05) increased with age (70-79 years, 1.8 odds ratio [OR] [95% CI, 1.4-2.3], > 79 years, 3.8 OR [95% CI, 2.9-4.9]), sex (female, 1.6 OR [95% CI, 1.3-1.9]), cerebral vascular occlusive disease (1.8 OR [95% CI, 1.3-2.5]), preoperative renal insufficiency (9.5 OR [95% CI, 7.7-11.7]), and more than three comorbidities (11.2 OR [95% CI, 3.6-35.4]). Multivariate analysis also showed that bad outcome was associated with the same variables in addition to hospital size (small/medium), year of procedure (1996), chronic obstructive pulmonary disease, and two to three comorbidities. CONCLUSIONS: Outcome after open repair of intact AAA across the United States is quite good. Older, sicker patients may benefit from nonoperative treatment or the potentially lower risk endovascular approaches.

Evaluation of a cerebral oximeter as a monitor of cerebral ischemia during carotid endarterectomy.

BACKGROUND: Stroke is an important contributor to perioperative morbidity and mortality associated with carotid endarterectomy (CEA). This investigation was designed to compare the performance of the INVOS-3100 cerebral oximeter to neurologic function, as a means of detecting cerebral ischemia induced by carotid cross-clamping, in patients undergoing carotid endarterectomy with cervical plexus block. METHODS: Ninety-nine patients undergoing 100 CEAs with regional anesthesia (deep or superficial cervical plexus block) were studied. Bilateral regional cerebrovascular oxygen saturation (rSO2) was monitored using the INVOS-3100 cerebral oximeter. Patients were retrospectively assigned to one of two groups: those in whom a change in mental status or contralateral motor deficit was noted after internal carotid clamping (neurologic symptoms; n = 10) and those who did not show any neurologic change (no neurologic symptoms; n = 90). Data from 94 operations (neurologic symptoms = 10 and no neurologic symptoms = 84) were adequate for statistical analyses for group comparisons. A relative decrease in ipsilateral rSO2 after carotid occlusion (calculated as a percentage of preocclusion value) during all operations (n = 100) was also calculated to determine the critical level of rSO2 decrease associated with a change in neurologic function. RESULTS: The mean (+/- SD) decrease in rSO2 after carotid occlusion in the neurologic symptoms group (from 63.2 +/- 8.4% to 51.0 +/- 11.6%) was significantly greater (P = 0.0002) than in the no neurologic symptoms group (from 65.8 +/- 8.5% to 61.0 +/- 9.3%). Logistic regression analysis used to determine if a change in rSO2, calculated as a percentage of preclamp value, could be used to predict change in neurologic function was highly significant (likelihood ratio chi-square = 13.7; P = 0.0002). A 20% decrease in rSO2 reading from the preclamp baseline, as a predictor of neurologic compromise, resulted in a sensitivity of 80% and specificity of 82.2%. The false-positive rate using this cutoff point was 66.7%, and the false-negative rate was 2.6%, providing a positive predictive value of 33.3% and a negative predictive value of 97.4%. CONCLUSION: Monitoring rSO2 with INVOS-3100 to detect cerebral ischemia during CEA has a high negative predictive value, but the positive predictive value is low.

Transrenal fixation of aortic stent-grafts for the treatment of infrarenal aortic aneurysmal disease.

PURPOSE: We evaluated our early experience with the transrenal fixation of aortic stent-grafts to determine the efficacy of this procedure and its effects on renal artery patency and hemodynamics. METHODS: Twenty-eight patients (22 men) had endoluminally placed modular bifurcated stent-grafts with a bare spring structure at the proximal end crossing the origin of both renal arteries; no patient with infrarenal fixation was included for analysis. The mean age of the patients was 75 +/- 7 years (range, 58-86 years); the mean aneurysm size was 5.8 +/- 0.8 cm (range, 4.7-7.2 cm). Eight patients had preoperative or intraoperative angiographic evidence of renal artery atherosclerotic disease, but only four vessels had luminal narrowing of 50% or greater. No complications were noted during stent-graft placement, and all patients have returned for follow-up visits, ranging from 1 to 12 months (mean follow-up, 6 +/- 4 months). Follow-up evaluations included clinical assessment, duplex ultrasound scan of the renal arteries and kidneys, and computed tomographic angiography. RESULTS: No evidence of lobular or sublobular perfusion defects of the renal parenchyma was detected postoperatively. Two patients exhibited postoperative changes in renal artery hemodynamics-one progressing from a 30% diameter reduction to a greater than 60% diameter stenosis at the 12-month follow-up visit and one with a normal renal artery preoperatively having elevated flow velocities indicative of a greater than 60% stenosis at the 1-month visit. Of 19 patients with normal preoperative renal function, only one has had persistently elevated serum creatinine levels. CONCLUSION: We conclude from this experience that the transrenal placement of open stents is safe and effectively excludes the aneurysm, potentially expanding the availability of this technique to more patients with a short infrarenal aortic neck. Long-term follow-up is essential to determine the overall efficacy of this technique and to identify potential effects on renal artery hemodynamics or kidney function.

Incidence of femoral and popliteal artery aneurysms in patients with abdominal aortic aneurysms.

OBJECTIVE: The purpose of this study was to determine the incidence of femoral and popliteal aneurysms in men and women who have abdominal aortic aneurysms (AAAs) and to assess potential etiologic differences in patients with and without these lower extremity aneurysms. METHODS: We studied 313 consecutive patients with AAAs encountered from 1995 to 1998 who underwent prospective ultrasound scanning to detect the presence or absence of femoral and popliteal aneurysms. Patients with and without these extremity aneurysms were compared for differences in potential etiologic risk factors with each other and with a statewide population of patients with AAAs. RESULTS: A total of 51 femoral and popliteal aneurysms were encountered, all occurring in male patients. Among the 251 men with AAAs, the incidence of femoral or popliteal aneurysms was 14%, compared with 0% among the 62 women with AAAs (P <.01). A family history of aneurysmal disease was present in only one (3%) of the 36 men with these extremity arterial aneurysms, a significant finding (P <.01) when compared with the family history that was positive for aneurysmal disease in 14 women (23%). Peripheral arterial occlusive disease affected 14 (39%) of the 36 men with peripheral arterial aneurysms versus 20 (9%) of the 215 men without these aneurysms (P <.01). Most other etiologic variables studied proved not to be different among the various groups of patients examined. CONCLUSION: The incidence of femoral and popliteal aneurysms in persons with AAAs appears higher than that noted previously. Femoral and popliteal aneurysmal disease preferentially affects men; however, the basis for this sex difference is unknown. Few common etiologic factors differed between men with and without these extremity aneurysms. Most femoral and popliteal artery aneurysms in this study were undetectable on physical examination, suggesting that ultrasound scanning is appropriate in the recognition of peripheral aneurysms among men with AAAs.

An assessment of contributions made by extracranial tissues during cerebral oximetry.

This study was designed to determine the extent of contribution made by extracranial tissues to estimation of regional cerebrovascular saturation (ScO2) during cerebral oximetry. Thirty four patients undergoing carotid endarterectomy under regional anesthesia were studied. Bilateral ScO2 monitoring with two INVOS 3100 A cerebral oximeters was used. Effect of occlusion of external carotid artery (ECA) for five minutes on ScO2 readings followed by occlusion of internal and common carotid arteries was studied. ScO2 readings at 1 minute intervals were stored on computer disks for off-line analysis. Numerical data were subjected to a two way repeated measures analysis of variance to study the effect of side (ipsilateral or contralateral) and phase (pre clamp, ECA clamp, ICA clamp and post clamp) of operation. A value of p<0.05 was considered significant. There was no significant change in ScO2 on the contralateral side. On the ipsilateral hemisphere ScO2 decreased from 67.4+/-8.5 to 65.6+/-8.3 with ECA occlusion and to 61.4+/-9.6 after ICA occlusion returning to 64.8+/-9.8 after all clamps were released. Decrease after ECA occlusion was not significant (p = 0.12) while that after ICA occlusion was significant when compared to pre clamp value (p<0.001). After release of all clamps ipsilateral ScO2 returned toward baseline but remained significantly lower (p<0.05) than pre clamp values. When readings from two hemispheres were compared, a significant difference (p<0.001) was noted during ICA occlusion only. We conclude that the mathematical algorithm used for calculation of ScO2 by INVOS 3100 A cerebral oximeter measures predominantly the intracranial cerebrovascular saturation.

Differential clinical workloads among faculty at a major academic health center.

OBJECTIVE: The authors analyzed patient care (1981-1995) and financial data (1991-1996) to determine if differential workloads existed at a major academic health center. SUMMARY BACKGROUND DATA: Academic health centers differ markedly from community-based medical centers, but they are required to compete with others who have a more circumscribed mission and a responsibility for providing less complex care. Changes in health care systems may lessen incentives to generate clinical revenue and may adversely affect educational and research programs. METHODS: Patient care data at the University of Michigan Health System were analyzed by discipline for level of activity from 1981 to 1995 and were compared to professional and institutional financial data from 1991 to 1995. RESULTS: Surgeons represented 11% of the total full-time physicians throughout the period of the study (94 of the 836 Medical Center physicians, 1995). They accounted for 33% of hospital admissions (11,616 of 35,101) and 16% of outpatient visits (92,364 of 568,738). Since 1981, surgeons experienced a 249% increase in total operative workload (6799-16,909 procedures), representing a 30% increase in operations/surgeon (138-180 operations). Surgical efforts in 1995 accounted for 29% of the total professional fee revenue and $240 million of the $512-million University of Michigan Hospital revenue. CONCLUSIONS: Surgeons had a greater collective and individual responsibility than did nonsurgeons for clinical activity and the financial viability of the academic health centers studied. Many proposals for financing health care delivery systems have the potential to exacerbate this differential. Restructuring of academic health centers must address this fact, lest their academic mission and scholarly activity be compromised.

Bypass grafting for chronic mesenteric ischemia.

A critical analysis of the literature suggests that there is no clearly superior technique for mesenteric revascularization and that the choice of operation must be individualized. Bypass grafting using either an antegrade or retrograde technique with prosthetic or autogenous conduits should produce excellent long-term results for most patients with this complex surgical problem. In most situations multiple vessel revascularizations are preferred. Surgeons caring for such patients must have the ability to utilize all available techniques to ensure optimal outcomes.

Gender differences in abdominal aortic aneurysm prevalence, treatment, and outcome.

PURPOSE: The purpose of this study was to investigate gender differences in the management of and outcome of surgery for abdominal aortic aneurysms (AAA). METHODS: Hospital discharge data from all acute care hospitals in Michigan, as compiled in the Michigan Inpatient Data Base, were retrospectively analyzed to assess sex differences in regard to AAA prevalence, treatment, and surgical outcome from 1980 to 1990. This population database included 11,512 women and 29,846 men 50 years of age and older with diagnoses of intact or ruptured AAA. RESULTS: Hospitalizations for intact or ruptured AAA were approximately five times more common among men compared with women. After controlling for age and year of surgery, men were 1.8 times as likely as women to have an intact AAA treated surgically and 1.4 times as likely to have a ruptured AAA treated surgically (95% confidence intervals, 1.7 to 1.9 and 1.2 to 1.7, respectively). Women who had operations for intact AAA had a 1.4 times greater risk of dying compared with men, and women who had operations for ruptured AAA had a 1.45 times greater risk of dying, after controlling for other predictors of death (95% confidence intervals, 1.14 to 1.73 and 1.10 to 1.90, respectively). CONCLUSIONS: In a population-based statewide experience, women who had intact or ruptured AAA were less likely than men to undergo aortic reconstruction and, when they did, were less likely than men to survive to discharge.

A novel protamine variant reversal of heparin anticoagulation in human blood in vitro.

PURPOSE: Protamine reversal of heparin anticoagulation during cardiovascular surgery may cause severe hypotension and pulmonary hypertension. A novel protamine variant, [+18RGD], has been developed that effectively reverses heparin anticoagulation without toxicity in canine experiments. Heretofore, human studies have not been undertaken. This investigation hypothesized that [+18RGD] would effectively reverse heparin anticoagulation of human blood in vitro. METHODS: Fifty patients who underwent anticoagulation therapy during vascular surgery had blood sampled at baseline and 30 minutes after receiving heparin (150 IU/kg). Activated clotting times were used to define specific quantities of [+18RGD] or protamine necessary to completely reverse heparin anticoagulation in the blood sample of each patient. These defined amounts of [+18RGD] or protamine were then administered to the heparinized blood samples, and percent reversals of activated partial thromboplastin time, thrombin clotting time, and antifactor Xa/IIa levels were determined. In addition, platelet aggregation assays, as well as platelet and white blood cell counts were performed. RESULTS: [+18RGD] and protamine were equivalent in reversing heparin as assessed by thrombin clotting time, antifactor Xa, antifactor IIa levels, and white blood cell changes. [+18RGD], when compared with protamine, was superior in this regard, as assessed by activated partial thromboplastin time (94.5 +/- 1.0 vs 86.5 +/- 1.3% delta, respectively; p < 0.001) and platelet declines (-3.9 +/- 2.9 vs -12.8 +/- 3.4 per mm3, respectively; p = 0.048). Platelet aggregation was also decreased for [+18RGD] compared with protamine (23.6 +/- 1.5 vs 28.5 +/- 1.9%, respectively; p = 0.048). CONCLUSIONS: [+18RGD] was as effective as protamine for in vitro reversal of heparin anticoagulation by most coagulation assays, was statistically more effective at reversal than protamine by aPTT assay, and was associated with lesser platelet reductions than protamine. [+18RGD], if less toxic than protamine in human beings, would allow for effective clinical reversal of heparin anticoagulation.

Systemic pressor response during hindlimb ischemia is inversely related to femoral artery pressure and fractional inspired oxygen.

BACKGROUND: Delayed-onset reflex increases in mean arterial pressure (MAP) occur during clamping of the infrarenal aorta. This study investigated the afferent limb of the reflex by independently altering femoral artery blood pressure (FBP) or fractional concentration of inspired oxygen (FIO2) while monitoring systemic arterial blood pressure. METHODS: The infrarenal aorta was divided, and an occlusive roller pump delivered incremental flow to the distal aorta thus controlling FBP. In six dogs the FBP was reduced in random order to 50, 40, 30, 20, and 10 mm Hg and held constant for 30 minutes. In another six dogs the FBP was held at 20 mm Hg, whereas the FIO2 was randomly varied among 0.13, 0.21, and 1.0 for 30-minute intervals. RESULTS: Under these conditions MAP was significantly and inversely correlated with FBP (MAP was 172 +/- 8 mm Hg when FBP was 10 mm Hg, p < 0.0001; MAP was 158 +/- 8 mm Hg when FBP was 20 mm Hg, p = 0.0001; MAP was 138 +/- 7 mm Hg when FBP was 30 mm Hg, p = 0.0048; and MAP was 130 +/- 7 mm Hg when FBP was 40 mm Hg, p = 0.0045). MAP was significantly and inversely related to the FIO2 value when FBP was fixed at 20 mm Hg (MAP of 186 +/- 9 mm Hg at FIO2 of 0.13 and was significantly higher than MAP of 163 +/- 11 mm Hg at FIO2 of 0.21, p = 0.01; and MAP of 157 +/- 10 mm Hg at FIO2 of 1.0, p = 0.0001). CONCLUSIONS: The magnitude of the delayed systemic pressor response is inversely proportional to the FBP. We suggest that this pressor response is also particularly sensitive, in part, to arterial blood oxygen tension when hindlimb perfusion pressure is low.

Performance on the radiology component of a critical clinical skills examination.

RATIONALE AND OBJECTIVES: Clinical competence certification is now required in some specialties in medicine. A Comprehensive Clinical Assessment (CCA) was created to test mastery of critical skills by students at the end of the 3rd year of medical school. METHODS: The CCA is a series of stations that test skills the faculty consider important for all medical students (eg, breast examination, electrocardiogram reading, chest pain assessment, ophthalmology photographs). The radiology station was designed to evaluate imaging skills believed to be taught and learned in the core 3rd-year rotations. RESULTS: External measures (National Board Examinations, grade point average, and overall score) of clinical performance of the 608 medical students who completed the CCA examination between 1991 and 1993 were found to be correlated with the radiology station scores. CONCLUSION: The radiology station in the CCA examination is a reproducible measure of clinical performance.

High resolution magnetic resonance imaging of the rat spinal cord.

A two turn saddle shaped surface coil receiver was developed that allowed high resolution magnetic resonance imaging of the rat spinal cord. This is particularly important in laboratory animals where central nervous system regions of interest are relatively small. A continuous copper wire 1.5 mm in diameter was wound into two turns 28 mm in diameter. The saddle shape of the second turn improved the homogeneity of the signal within the region of interest and maintained sufficient field of view and depth of penetration. The quality factor (Q) for the surface coil was Q = 199 unloaded, and Q = 60 loaded. Using this surface coil with a GE CSI II 2.0 Tesla small bore magnet, spin echo T1 (TR = 500 msec, TE = 25 msec) and T2 (TR = 2000 msec, TE = 100 msec) weighted images were obtained in cross section, using 2 mm slice thickness with 2 excitations per phase encoding step. A sagittal gradient echo (rapid scan, TR = 85 msec, TE = 10 msec) was used to document reestablishment of vascular flow following ischemia. Spinal cord ischemia was induced by 14 minute temporary occlusion of spinal cord blood supply. MRI was performed at 18 hours following ischemia. There was a 1.4 fold increase in T2 image intensity in ischemic rat spinal cord (n = 4), consistent with edema formation, compared to normal rat spinal cord (n = 4). Preliminary studies show that similar high resolution images can be performed on the rat brain. This technique uses standard MRI equipment and the surface coil is made from inexpensive readily available materials. There are various animal models of cerebral and spinal cord injury that would benefit from improved high resolution MRI. This coil design may have application in larger animal models and the clinical setting.

Infrarenal aortic clamp hypertension is exacerbated by baroreceptor blockade.

Aortic clamp-induced hypertension has long been implicated in the cardiovascular mortality and morbidity following infrarenal aortic operations. We studied the physiologic mechanisms leading to clamp-induced hypertension. Mean arterial pressure (MAP), cardiac output, heart rate, and left ventricular pressure were measured in alpha-chloralose-anesthetized dogs. Animals received alpha, beta, both alpha and beta, or no adrenergic blockade (n = 3, 4, 12 and 7, respectively). The infrarenal aorta was clamped following ligation of the infrarenal collateral vessels (lumbar, circumflex iliac, and tail arteries). Statistical analysis used paired t tests within groups, and ANOVA and unpaired t tests between groups, with Bonferroni's correction as indicated. Following placement of the clamp, MAP increased immediately in all groups, with magnitude of the increase related to the extent of adrenergic blockade. MAP increased 5.6 +/- 0.8 mm Hg with no blockade (P = 0.0005), 6.7 +/- 0.8 mm Hg with alpha blockade (P = 0.0153), 15 +/- 3.1 mm Hg with beta blockade (P = 0.0163), and 16.7 +/- 1.3 mm Hg with combined alpha and beta blockade (P < 0.0001). The increase in MAP immediately following infrarenal aortic clamping was most pronounced with combined alpha and beta blockade. We suggest that acute intraoperative hypertension associated with infrarenal aortic clamping is caused by the attenuation of compensatory baroreceptor reflex mechanisms.

Cerebral oximetry in patients undergoing carotid endarterectomy under regional anesthesia.

BACKGROUND AND PURPOSE: Near-infrared spectroscopy is a technique that can potentially monitor changes in cerebral oxygenation. There are at present limited clinical data regarding the value of this technology in relating neurological outcome to cerebrovascular hemoglobin oxygen saturation (ScO2). This investigation reports changes in ScO2 due to carotid cross-clamping during carotid endarterectomy in awake patients. METHODS: ScO2 was monitored in 38 adult patients undergoing 41 carotid endarterectomies under regional anesthesia. Ipsilateral and contralateral hemispheres were monitored simultaneously during 36 operations, with ipsilateral monitoring alone in the remaining 5 operations. RESULTS: No significant difference was detected between ipsilateral and contralateral ScO2 during preclamp or postclamp periods. Carotid cross-clamping caused a statistically significant (P < .01) decrease in the ipsilateral ScO2, which decreased from 71.8 +/- 6.91% to 65.8 +/- 8.2%, while the contralateral ScO2 remained stable at 70.5 +/- 7.5% and 70.3 +/- 7.9%. The change in ipsilateral ScO2 ranged from +2.6% to -28.6% of the preclamp value. The difference between ipsilateral and contralateral ScO2 during cross-clamping was statistically significant (P < .001). The duration of cross-clamping was 39 +/- 11 minutes (range, 18 to 89 minutes). The decrease in ipsilateral ScO2 was highly variable from patient to patient and did not correlate with the duration of cross-clamping. CONCLUSIONS: These results suggest that carotid artery occlusion causes a statistically significant but variable decrease in ScO2 in the majority of patients. Data in this investigation provide a range of ScO2 values that was not associated with a clinically detectable neurological dysfunction.

Abdominal aortic aneurysms.

Certain biological differences between men and women are relevant to the problem of AAA, and are widely accepted. Women unequivocally have smaller aortas. The size difference correlates with a variety of anthropomorphic measurements, but is most strongly associated with body surface area. In women the compliance of the aorta decreases in linear fashion with age, whereas in men the decrease in compliance is exponential with age. Women appear to be underrepresented in AAA surgical series (typically 18% to 20% of operative cases) compared with autopsy studies (29% to 32%), ultrasound screening studies (19% to 25%), and mortality studies (34% of the 14,982 deaths due to AAA in the US in 1988). Several lines of evidence suggest that women with AAA are less likely than men to be referred for surgery, and that, when referred, they have higher mortality rates. The reasons for these differences are unclear. The very factors that allow increased longevity in women may have an adverse effect on the ability to tolerate a major surgical stress. Wenger et al have suggested that psychosocial and economic factors may affect women's decisions to seek care, or their choice of therapeutic options. Lack of knowledge among practitioners of gender-related aortic size differences and overreliance on simplistic clinical paradigms that dictate operations for 5-cm diameter aneurysms and watchful waiting for 4- to 5-cm AAAs may result in unintended bias in patient selection. It may be that a 5-cm diameter AAA in a woman with a predicted normal aortic size of 1.4 cm represents a more advanced stage of disease than a 5-cm diameter AAA in a man with a normal aortic diameter of 2.5 cm. More precise and detailed algorithms are needed to permit clinicians to tailor decisions to patients' size, sex, and risk factors. Development of such algorithms requires expansion of clinical and epidemiological studies to include enough women to make precise risk estimates.

Gadolinium-enhanced magnetic resonance angiography of abdominal aortic aneurysms.

PURPOSE: The objective of this study was to assess the usefulness of gadolinum-enhanced magnetic resonance angiography (MRA) for defining anatomic features relevant to performing aortic surgery for aneurysmal disease. METHODS: Anatomic data defined by MRA, including abdominal aortic aneurysm (AAA) size and character, as well as the status of the celiac, mesenteric, renal, and iliac arteries, were correlated with angiography, ultrasonography, computed tomography, or operative data in 43 patients. Five MRA sequences were obtained in an hour-long examination optimized for aortoiliac, splanchnic, and renal artery imaging at 1.5 T in a body coil. Four of the sequences were performed during or after infusion of gadolinium to improve image quality. RESULTS: MRA correctly defined the maximum aneurysm diameter, as well as its proximal and distal extent in all patients. MRA detected 33 of 35 significant stenoses among 153 splanchnic, renal, or iliac branches examined (sensitivity = 94% and specificity = 98%). MRA did not resolve the degree of aortic branch stenotic disease sufficiently to precisely grade its severity. MRA did not reliably define the status of the inferior mesenteric artery, lumbar arteries or internal iliac arteries. One ruptured AAA and one inflammatory AAA were correctly diagnosed by MRA. No patient had a contrast reaction or contrast-induced renal toxicity related to administration of gadolinium. CONCLUSION: Gadolinium-enhanced MRA of AAA provides appropriate, essential anatomic information for aortic reconstructive surgery in a 1-hour examination devoid of contrast-related renal toxicity or catheterization-related complications attending conventional arteriography.

Splenic arteriovenous fistula.

Splenic arteriovenous fistulas are uncommonly encountered, yet they can invoke serious pathophysiological consequences. Four patients treated for splenic fistulas at our institution over the last decade were combined with all previous case reports to produce the most extensive review yet reported, totalling 91 patients. Common etiologies included atherosclerotic aneurysm rupture (44%), congenital malformation (20%), and prior splenectomy (13%). The most frequent manifestation was gastrointestinal hemorrhage (48%), which was most prevalent with congenital fistulas (61% p < 0.05) or fistulas located proximally (54%, p < 0.005). Chronic portal hypertension that was usually characterized by preservation of hepatic function developed in 65%. Management included splenectomy (70%), fistula excision (59%), and occasionally required distal pancreatectomy (10%). Persistent portal hypertension necessitated operative portosystemic shunting in select cases (9%), with an overall 30 day operative mortality of 9%. While percutaneous embolization provided an additional therapeutic option in 4%, optimal management continues to include operative intervention.

Pediatric renovascular hypertension: a thirty-year experience of operative treatment.

PURPOSE: This study was undertaken to characterize the changing operative treatment of pediatric renovascular hypertension and subsequent outcomes in a 30-year experience at a single institution. METHODS: Clinical data were analyzed on 57 pediatric patients, 24 girls and 33 boys, ranging in age from 10 months to 17 years, who underwent operations for renovascular hypertension from 1963 to 1993 at the University of Michigan. Renal artery disease included atypical medial-perimedial dysplasia, often with secondary intimal fibroplasia (88%), and inflammatory mural fibrosis (12%). Abdominal aortic narrowings affected 15 patients. Data were categorized into three chronologic eras (I:1963-1972, II:1973-1980, and III:1981-1993) to allow identification of therapeutic trends. RESULTS: Primary surgical procedures were undertaken 74 times. Ex vivo reconstruction was necessary once. Primary operations included aortorenal bypass with autogenous vein grafts (n = 26) or internal iliac artery grafts (n = 7); iliorenal bypass with vein grafts (n = 2); renal artery resection beyond the stenosis and reimplantation into the aorta (n = 10), the main renal artery (n = 2), an adjacent segmental renal artery (n = 3), or the superior mesenteric artery (n = 3); renal artery resection and reanastomosis (n = 3); focal renal arterioplasty (n = 2); operative dilation (n = 7); splenorenal bypass (n = 2); and primary nephrectomy (n = 7). Among 23 primary operations performed in era I, 56.5% were aortorenal bypasses with vein grafts, but in era III this form of revascularization represented only 3% of 33 primary operations. No reimplantations were performed in era I, whereas reimplantations accounted for 51.5% of era III procedures. Thirteen patients underwent staged or concomitant aortic reconstructions with thoracoabdominal aortoaortic bypass grafts (n = 5) or patch aortoplasty (n = 8). Fourteen patients underwent a total of 20 secondary operations, including seven secondary nephrectomies. Operative therapy benefited 98% of these children: hypertension was cured in 45 (79%), improved in 11 (19%), and unchanged in one (2%). There were no operative deaths. CONCLUSIONS: Contemporary surgical management emphasizes direct reimplantation of main renal arteries into the aorta, reimplantation of segmental arteries into adjacent renal arteries, patch aortoplasty for associated abdominal aortic coarctations, and single-stage revascularizations. Pediatric patients with renovascular hypertension clearly benefit from carefully executed operative therapy.

Prevention of paraplegia during thoracic aortic cross-clamping: importance of patent internal mammary arteries.

PURPOSE: Unexplained anatomic and physiologic factors account for the unacceptably high rate of paraplegia/paresis after thoracoabdominal aortic reconstruction. We assessed the neurologic significance of patent internal mammary arteries (IMAs) in a novel rat model of aortic clamping in which the aortic origins of the intercostal arteries (ICAs) were occluded. METHODS: Twenty anesthetized, intubated, and halothane-ventilated adult male rats had catheters placed in the carotid and femoral arteries. ICAs arising from the aorta were divided at their origins through a left thoracotomy. IMAs were either divided (IMA-OUT, n = 10) or left intact (IMA-IN, n = 10). Proximal and distal descending aortic clamps were placed for 7 minutes. A neurologic deficit score (NDS) was assigned at 1, 4, 18, 24, and 48 hours by use of an established scoring system. RESULTS: The mean IMA-IN NDS was statistically better than the mean IMA-OUT NDS at 1, 4, 18, and 24 hours with p = 0.0005, 0.0014, 0.0098, and 0.0151, respectively. Moreover, the mortality rate in the IMA-OUT group was statistically greater than in the IMA-IN group (p = 0.0036). CONCLUSION: In this model, patent IMAs prevent paraplegia when the ICAs are occluded at their aortic origin and the aorta is clamped for 7 minutes.