Measurement of Neutral-Current K

Neutral-current production of K^{+} by atmospheric neutrinos is a background in searches for the proton decay p→K^{+}ν[over ¯]. Reactions such as νp→νK^{+}Λ are indistinguishable from proton decays when the decay products of the Λ are below detection threshold. Events with K^{+} are identified in MINERvA by reconstructing the timing signature of a K^{+} decay at rest. A sample of 201 neutrino-induced neutral-current K^{+} events is used to measure differential cross sections with respect to the K^{+} kinetic energy, and the non-K^{+} hadronic visible energy. An excess of events at low hadronic visible energy is observed relative to the prediction of the neut event generator. Good agreement is observed with the cross section prediction of the genie generator. A search for photons from π^{0} decay, which would veto a neutral-current K^{+} event in a proton decay search, is performed, and a 2σ deficit of detached photons is observed relative to the genie prediction.

Direct Measurement of Nuclear Dependence of Charged Current Quasielasticlike Neutrino Interactions Using MINERvA.

Charged-current ν_{µ} interactions on carbon, iron, and lead with a final state hadronic system of one or more protons with zero mesons are used to investigate the influence of the nuclear environment on quasielasticlike interactions. The transferred four-momentum squared to the target nucleus, Q^{2}, is reconstructed based on the kinematics of the leading proton, and differential cross sections versus Q^{2} and the cross-section ratios of iron, lead, and carbon to scintillator are measured for the first time in a single experiment. The measurements show a dependence on the atomic number. While the quasielasticlike scattering on carbon is compatible with predictions, the trends exhibited by scattering on iron and lead favor a prediction with intranuclear rescattering of hadrons accounted for by a conventional particle cascade treatment. These measurements help discriminate between different models of both initial state nucleons and final state interactions used in the neutrino oscillation experiments.

Ruptured hepatic artery aneurysm with hepatic artery-to-portal vein fistula. Preservation of portal flow by autogenous vein reconstruction.

Hepatic artery aneurysms are uncommon lesions that have varied clinical presentations. Rupture into the portal vein has occasionally been reported, as has associated gastrointestinal bleeding. A case is described in which an unusually large hepatic artery aneurysm ruptured into the portal vein, destroying a major portion of its wall. Reconstruction was accomplished successfully by use of an autogenous saphenous vein patch with preservation of hepatopetal portal flow.

Aneurysms of the internal iliac artery.

Twenty-one patients with aneurysms of the internal iliac artery were identified over a 14-year period. Group A included those patients who had aneurysms associated with aortoiliac artery aneurysms and group B were those who had isolated internal iliac aneurysms. The natural course of these aneurysms is one of progressive expansion and rupture. A pulsatile pelvic mass, often associated with compression symptoms of the neurologic, gastrointestinal, genitourinary, and peripheral venous structures, is often present. Aortography, computerized tomographic scanning, and abdominal ultrasonography are the most useful diagnostic procedures. Proximal ligation and endoaneurysmorrhaphy make up the most appropriate surgical treatment. A case report is presented of a patient who underwent successful elective embolization as an alternative method of management.

The significance of elongation and angulation of the carotid artery: a negative view.

Many authors have postulated that angulation of the carotid artery is a cause of stroke and recommend corrective operation. Symptoms attributed to such lesions are often nebulous and unrelieved by the operation, and proof is lacking that unselected patients who have this condition have a risk of stroke exceeding operative risk. A review of 282 cerebral angiograms showed an incidence of elongation and potential angulation of 43 percent in children and 20 percent in adults. Acutal angulation was not found in children, however, and no child was suspected of having cerebral ischemia. Of 47 adults with potential angulation, 17 were suspected of having cerebral ischemia, the remainder having a variety of other lesions, such as tumors, aneurysm, and intracranial hemorrhage. Of the 17 having suspected cerebral ischemia, all had alternative explanations for their symptoms (hypertension, intracranial atherosclerosis), except one whose symptoms were completely inappropriate to the carotid distribution. A single patient had a completed stroke, demonstrable angulation, and only mild hypertension. Elongation and potential angulation of the carotid artery is common but usually coexists with other lesions. If the finding is postulated as the cause for neurologic morbidity the surgeon must be assured that symptoms are clearly neurologic, that no other cause exists, that angulation reduces the carotid lumen significantly and reproduces symptoms, and that the risk of operation is less than the expected risk of stroke in untreated patients.

Reoperative abdominal arterial surgery--a ten-year experience.

The safety and durability of elective reconstructive procedures of the abdominal aorta and its major branches are universally accepted; however, late complications continue to threaten limbs and lives of a minority of patients. The strategy of managing such revascularization failures has received inadequate attention. Between February 1971 and July 1981, 76 patients underwent 83 remedial, transabdominal revascularization procedures because of failed reconstructions. Group I consisted of 34 patients with occlusive complications (0% remedial operative mortality rate); group II, 21 patients with prosthetic sepsis including graft-enteric fistula (14% operative mortality); group III, 11 patients with aneurysmal degeneration (36% operative mortality); and group IV, 10 patients with visceral ischemia (0% operative mortality). The remedial operative mortality rate for the combined groups was 7.9%. Limb preservation was the rule in group I (91%); however, 29% of limbs at risk in group II ultimately required major amputation (15% early, 14% late). All patients in group II without an established graft-enteric fistula were saved; however, three of ten with active hemorrhage died of the sequelae of hypovolemic shock. Progressive arteriosclerotic morbidity and massive intraoperative bleeding accounted for the high mortality rate in group III. Favorable results were obtained in reoperation for recurrent visceral ischemia (renal ischemia in five, mesenteric ischemia in five). On the basis of this experience, an aggressive surgical approach seems justified. First, complete bifemoral revascularization performed at the time of original operation should reduce the need for reoperation. Second, elective, transabdominal remedial arterial surgery can be done with acceptable morbidity and mortality rates. Third, graft-enteric erosions and periprosthetic sepsis must be treated aggressively to avoid life-threatening sepsis and hemorrhage. Finally, anatomic revascularization can be performed successfully after a suitable period following removal of an infected retroperitoneal prosthesis.

Does contralateral carotid occlusion influence neurologic fate of carotid endarterectomy?

Divergent opinions regarding operative risks and late prognosis of patients undergoing endarterectomy for carotid stenosis with contralateral carotid occlusion have prompted a review of the experience at Emory University Hospital from Jan. 1, 1978, through Dec. 31, 1982. Fifty-four patients (37 men, 17 women; mean age 63 years) who underwent carotid endarterectomy (CEA) with contralateral carotid occlusion (group I) were compared with 410 demographically similar patients without contralateral carotid occlusion (group II) who underwent 503 CEAs during the same interval. CEA indications in group I were the following and were proportionately similar to those of group II: hemispheric transient ischemic attacks, 22 patients; asymptomatic stenosis, 12 patients; nonhemispheric symptoms, 11 patients; previous cerebral infarction, eight patients; and vascular tinnitus, one patient. General anesthesia, routine intraluminal shunting, systemic heparinization, and arteriotomy closure without patch were routinely employed in both groups. Three patients in group I suffered permanent neurologic deficits after operation (5.6%) and two had transient postoperative deficits with complete recovery. Ten patients (2.0%) in group II suffered permanent neurologic deficits and 10 patients experienced transient neurologic events after operation. Neither the transient nor the permanent neurologic deficit rates were statistically different (p greater than 0.05; Fisher exact test) in the two groups. Operative mortality rates for group I and group II were 0% and 0.8%, respectively, and were not significantly different (p greater than 0.10; Fisher exact test). Late postoperative ischemic brain infarctions occurred in two patients in group I (3.8%) and in 13 patients (3.6%) in group II (p greater than 0.10; Fisher exact test). Kaplan-Meier survival analyses were virtually identical in both groups, with the majority of deaths caused by cardiac occlusion may undergo CEA with morbidity and mortality rates similar to those without contralateral occlusions. Contralateral carotid occlusion does not necessarily portend an unfavorable early or late prognosis after CEA.

Management of postendarterectomy neurologic deficits.

A series of 1,023 carotid endarterectomies were done between 1969 and 1980, with 31 patients (3.1%) having postendarterectomy neurologic deficits. Death ensued in seven patients (0.7%), and permanent neurologic deficits occurred in five patients (0.5%). Analysis of causes indicated that microemboli and thrombosis at the operative site are most frequent. When thrombosis is recognized early, this condition can be corrected by prompt reoperation. An algorithm can be used for guidance in management. Preventive measures include preoperative neurologic and cardiovascular stability that is maintained through the recovery period, meticulous operative dissection, and use of a temporary intraluminal shunt.

Nonoperative management of selected popliteal aneurysms.

In the management of 95 popliteal aneurysms, surgical therapy was initially successful in 90% of operations, while major limb amputation was required in 6%. Durability of surgical reconstruction was improved if autogenous saphenous vein was used and if the reconstruction was performed before development of complications. Twenty asymptomatic popliteal aneurysms were repaired without loss of limb and with a five-year secondary cumulative patency rate of 93%. Among 26 small asymptomatic popliteal aneurysms managed without operation, complications developed in only two (8%) during the period of observation. Because of the demonstrated safety and efficacy of surgical treatment, repair of popliteal aneurysms is recommended in acceptable operative candidates. However, there exists a subgroup of asymptomatic higher-risk patients with small popliteal aneurysms in whom a conservative nonoperative approach is reasonably safe.

Abdominal aortic surgery and horseshoe kidney.

Seventy cases, including the six reported here, of aortic operations in patients with horseshoe kidney were reviewed. Anomalous renal arteries were encountered in 42 (60%) of these patients. We concluded that accurate preoperative diagnosis and angiographic delineation of aberrant renal arteries facilitate preservation of renal blood supply. When accessory or anomalous arteries cannot be preserved in situ, they should be reimplanted into the aortic prosthesis. Symphysiotomy may improve operative exposure and when necessary is a safe maneuver.

Segmental aortic occlusion: An unusual lesion found in menopausal women.

A subgroup of patients with aortoiliac atherosclerosis are perimenopausal women in whom the lesions are confined to the midportion of the terminal aorta. The lesions occur in relatively small, though not hypoplastic, vessels, and it is speculated that the relatively small size of the terminal aorta functions as a long stenosis with resultant predisposition to atheroma formation. Other etiologic factors are not identified except for smoking. Endarterectomy results in satisfactory restoration of distal arterial flow. Recurrence has not been observed but the question exists as to whether replacement of the small segment with a larger prosthesis may be more appropriate in view of the possible etiology described.

Hemodynamics of intravenous nitroglycerin during aortic clamping.

Anesthetic management and dosage schedules of vasodilators have not been standardized in many studies of aortic cross clamping (CCL). For this reason, 25 consecutive patients with arteriosclerotic disease of the aorta were studied, all having received the same anesthetic management. Six patients who received nitroglycerin during the cross clamp period, at a dosage of 0.25 micrograms/kg/min, were compared with 19 who underwent CCL without the drug. Contractility was maintained in the nitroglycerin group, but not in the other group. Despite a low cardiac index in both groups, peripheral blood flow was adequate only in the nitroglycerin group. Intrapulmonary shunt was higher in the nitroglycerin group, but it did not significantly decrease the Pao2. Nitroglycerin infusion seems to be helpful in maintaining pre-CCL contractility and adequacy of peripheral blood flow.

Revascularization for severe limb ischemia.

Patients with rest pain or tissue necrosis (generally correlated with a tibial-brachial pressure index of less than 0.25) have a high probability of limb loss unless revascularization is done. These problems are usually associated with extensive and multiple segments of anatomical occlusive disease. A review of 359 patients with such problems indicates that revascularization was done in 86%, with initial success in 92% of patients. The durability of successful limb preservation proved good, with 90% of patients having a comfortable, useful limb to time of death or for one year or longer after operation. Cumulative patency rates were 90% at five years for aortofemoral reconstructions, 70% at five years for femoropopliteal bypasses, and 49% at five years for femorotibial grafts. Cumulative limb salvage rates were 93%, 81%, and 67% at five years in the same categories, respectively.

Massive intracerebral hemorrhage following carotid endarterectomy.

To our knowledge, a particularly lethal complication of carotid endarterectomy, intracerebral hemorrhage, has not been given due consideration in the literature concerning carotid surgery. In the Atlanta area, massive intracranial hemorrhage developed in ten patients following routine carotid endarterectomies performed during a recent ten-year period. All ten of the patients in this series died despite a variety of therapeutic interventions. Risk factors may include the following: extreme arterial stenosis with resultant postoperative hyperperfusion, involvement of multiple extracranial cerebral vessels, postoperative systemic hypertension, and administration of anticoagulant or antiplatelet medications. Unfortunately, identification of the subset of patients potentially at risk for this complication is difficult, and, to date, therapy has been generally ineffective.

South American plants III: Isolation of fulvoplumierin from Himatanthus sucuuba (M. Arg.) Woodson (Apocynaceae).

The bark of Himatanthus sucuuba was screened for pharmacological and anticancer activities. The lactone, fulvoplumierin (C14H12O4), was isolated from the n-hexane fraction. The identity was proven by elemental analysis and IR, mass spectral, and melting-point determinations. Reference samples were used for comparison.

South American plants II: taspine isolation and anti-inflammatory activity.

Croton lechleri L. (Euphorbiaceae), a plant from the Upper Amazon Valley of Peru, yielded the alkaloid taspine. The anti-inflammatory activity of taspine hydrochloride was studied using the carrageenan-induced pedal edema method, the cotton pellet-induced granuloma method, and the adjuvant polyarthritis model.

Antibiotics as an aid in the prevention of infections after peripheral arterial surgery.

Patients having arterial reconstructive operations appear to have a comparatively high attack rate of hospital-acquired infections. A protocol for administration of antibiotic prophylaxis to such patients was designed to minimize major adverse effects while evaluating the effect on attack rate of hospital acquired infections. Short intensive therapy with an appropriate antibiotic during a period of time surrounding the operative procedure itself is emphasized. The attack rate of nosocomial infections declined from approximately 12 to approximately 3 per cent and wound infections occurred in only seven of 811 patients. Administration of antibiotics according to this protocol appears to reduce the expected attack rate of nosocomial infections.

Preoperative aortography before abdominal aortic aneurysmectomy?

A review of 100 consecutive patients undergoing abdominal aortic aneurysmectomy was made to assess the value and necessity of preoperative aortography. Comparison of arteriography with physical examination, plain roentgenograms and ultrasonography suggests that angiography is required only for evaluation of specific problems. Indications for the selective use of preoperative aortography are proposed.

Infected aortobifemoral prosthesis--a dreaded complication.

From 1980 to 1985 13 patients were identified with infected aortofemoral grafts. Potential predisposing factors identified included a history of multiple femoral arterial procedures (10 patients; 77%) as well as perioperative infections occurring at the time of a prior femoral operation (five patients; 38%). Patients presented with suppurative groin infections (11) or ruptured pseudoaneurysms (2). Two who had previously undergone bilateral amputations were managed by removal of their aortic grafts without revascularization. Eleven other patients were managed by excision of the entire prosthesis (6 aortic grafts), partial graft excision (five graft limbs) or local treatment alone (three graft limbs). Revascularization through uninfected tissue planes was performed on 14 limbs with salvage of 11 (limb salvage 79%); whereas three limbs not revascularized required major amputation (limb salvage 0%). Despite an aggressive surgical approach five patients (38%) required a major amputation and there were three deaths (23% mortality). Once the diagnosis of an infected graft is made, early graft excision and prompt revascularization are encouraged.

Is there a place for external grafting of arterial aneurysms in selected patients?

External grafting of aortic and iliac artery aneurysms has been accomplished in 33 highly selected poor risk patients over a period of eight years. This experience demonstrated that external grafting of aneurysms is a technically demanding operative procedure which is accompanied by significant early and late morbidity. The technique does effectively reduce the occurrence rate of late rupture of aneurysms, however, at least for the period of observation of this study. Thus, while external grafting certainly is not generally applicable, the procedure may be used to advantage in highly selected situations, possibly including: 1. Long segment aneurysms of the thoracic or thoraco-abdominal aorta. 2. Aneurysms involving the renal arteries in poor risk patients. 3. As reinforcement for dilated arterial segments adjacent to sites of vascular anastomosis.