Pattern formation in Faraday instability-experimental validation of theoretical models.

Two types of resonance-derived interfacial instability are reviewed with a focus on recent work detailing the effect of side walls on interfacial mode discretization. The first type of resonance is the mechanical Faraday instability, and the second is electrostatic Faraday instability. Both types of resonance are discussed for the case of single-frequency forcing. In the case of mechanical Faraday instability, inviscid theory can forecast the modal forms that one might expect when viscosity is taken into account. Experiments show very favourable validation with theory for both modal forms and onset conditions. Lowering of gravity is predicted to shift smaller wavelengths or choppier modes to lower frequencies. This is also validated by experiments. Electrostatic resonant instability is shown to lead to a pillaring mode that occurs at low wavenumbers, which is akin to Rayleigh Taylor instability. As in the case of mechanical resonance, experiments show favourable validation with theoretical predictions of patterns. A stark difference between the two forms of resonance is the observation of a gradual rise in the negative detuning instability in the case of mechanical Faraday and a very sharp one in the case of electrostatic resonance. This article is part of the theme issue 'New trends in pattern formation and nonlinear dynamics of extended systems'.

Effectiveness of the Cobra aortic catheter for dual-temperature management during adult cardiac surgery.

OBJECTIVES: In animals the Cardeon Cobra catheter (Cardeon Corp, Cupertino, Calif) allows independent control of aortic arch and descending aortic temperatures and profoundly reduces cerebral embolization during bypass. This investigation describes the first clinical use of the device during adult cardiac surgery. The purpose of the study was to confirm that the Cobra catheter delivers adequate cerebral and systemic perfusion while providing simultaneous cerebral hypothermia and systemic normothermia during cardiopulmonary bypass. METHODS: In a prospective multicenter study the Cobra aortic catheter was placed in 20 adults undergoing cardiopulmonary bypass. Arch and corporeal temperatures, bypass flows, and arterial blood pressures were recorded intraoperatively. Jugular bulb and mixed venous oxygen saturation was used to assess the adequacy of cerebral and systemic perfusion. RESULTS: Surgeons at 3 institutions placed the Cobra catheter in patients undergoing coronary artery bypass grafting (n = 13), valve (n = 3), and combined valve-bypass (n = 4) operations. Mean total bypass flows of 2.1 +/- 0.2 L x min(-1) x m(-2) maintained mean arterial pressures in arch and descending aortic circulations of greater than 55 mm Hg. A mean differential of 4.3 degrees C between arch and descending aortic temperatures was established before crossclamp application, and a mean maximum temperature differential of 7 degrees C was established during bypass. A 2.4 degrees C temperature differential was maintained at crossclamp removal. Cerebral and systemic venous oxygen saturation remained greater than 65% during bypass. CONCLUSIONS: The Cobra device met all expectations for an arterial cannula with adequate perfusion to the arch and corporeal circulations. Dual perfusion with the Cobra catheter allows for independent temperature control during cardiopulmonary bypass with simultaneous cerebral hypothermia and systemic normothermia.

Concomitant subclavian and coronary artery disease.

BACKGROUND: Proximal subclavian artery occlusive disease in the presence of a patent internal mammary artery used as a conduit for a coronary artery bypass graft procedure may cause reversal of internal mammary artery flow (coronary-subclavian steal) and produce myocardial ischemia. METHODS: We reviewed outcome to determine whether subclavian artery revascularization can provide effective protection from and treatment for coronary-subclavian steal. Between 1985 and 1997, 20 patients had either concomitant subclavian and coronary artery disease diagnosed before operation (group 1, 5 patients) or symptomatic coronary-subclavian steal occurring after a previous coronary artery bypass graft procedure (group 2, 15 patients). Patients in group 1 received direct subclavian artery bypass and a simultaneous coronary artery bypass graft procedure in which the ipsilateral internal mammary artery was used for at least one of the bypass conduits. Patients in group 2 received either extrathoracic subclavian-carotid bypass (5 patients, 33.3%) or percutaneous transluminal angioplasty and stenting (10 patients, 66.7%) as treatment for symptomatic coronary-subclavian steal. RESULTS: All patients were symptom-free after intervention. One patient treated with percutaneous transluminal angioplasty and stenting died of progressive renal failure. Follow-up totaled 58.5 patient-years (mean, 3.1 years/patient). In group 1, primary patency was 100% (mean follow-up, 3.7 years). In group 2, one late recurrence was treated by operative revision, yielding a secondary patency rate of 100% (mean follow-up, 2.9 years). CONCLUSIONS: Subclavian artery revascularization can provide effective protection from and treatment for coronary-subclavian steal with acceptably low operative risk. Midterm follow-up demonstrates good patency.

Presentation of infantile aortic coarctation in an adult.

Rarely, the initial presentation of aortic coarctation, a congenital anomaly, occurs in adults. Surgical repair is indicated for symptomatic patients. We report the case of a 68-year-old woman who underwent successful surgical repair of the infantile (preductal) type of aortic coarctation with use of an interposition graft.

Celiac artery compression syndrome.

Celiac artery compression syndrome occurs when the median arcuate ligament of the diaphragm causes extrinsic compression of the celiac trunk. We report a case of a 65-year-old woman who presented with a three-month history of postprandial abdominal pain, nausea and some emesis, without weight loss. There was a bruit in the upper mid-epigastrium and the lateral aortic arteriography revealed a significant stenosis of the celiac artery. At operation, the celiac axis was found to be severely compressed anteriorly by fibers forming the inferior margin of the arcuate ligament of the diaphragm. The ligament was cut and a vein by-pass from the supraceliac aorta to the distal celiac artery was performed. The patient remains well and free of symptoms two and a half years since operation.In this report we discuss the indications and the therapeutic options of this syndrome as well as a review of the literature is being given.

Sinus of Valsalva aneurysm or fistula: management and outcome.

BACKGROUND: Few large or long-term series exist regarding the management of patients with sinus of Valsalva aneurysms or fistulas (SVAFs). METHODS: Between 1956 and 1997, 129 patients presented with a ruptured (64 cases; 49.6%) or nonruptured (65 cases; 50.4%) SVAF. The patients included 88 men and 41 women, with a mean age of 39.1 years. Associated findings included a history of endocarditis (42 cases; 32.6%), a bicuspid aortic valve (21 cases; 16.3%), a ventricular septal defect (15 cases; 11.6%), and Marfan's syndrome (12 cases; 9.3%). Operative procedures included simple plication (61 cases; 47.3%), patch repair (52 cases; 40.3%), aortic root replacement (16 cases; 12.4%), and aortic valve replacement/repair (75 cases; 58.1%). RESULTS: There were five in-hospital deaths (3.9%): four due to preexisting sepsis and endocarditis and one that followed dehiscence of the repair in a patient with Marfan's syndrome. Two patients (1.6%) had strokes during the early postoperative period. The survivors were followed up for 661.1 patient-years (5.3 years/patient). The following late complications occurred: prosthetic valve malfunction (5 cases; 3.9%), prosthetic valve endocarditis (3 cases; 2.3%), SVAF recurrence (2 cases; 1.6%), thrombosis (1 case; 0.8%), and anticoagulation-related bleeding (1 case; 0.8%). CONCLUSIONS: Resection and repair of SVAF entails an acceptably low operative risk and yields long-term freedom from symptoms. Early, aggressive treatment is recommended to prevent endocarditis or lesional enlargement, which causes worse symptoms and necessitates more extensive repair.

Endoscopic harvesting of the greater saphenous vein for aortocoronary bypass grafting.

We conducted an observational study to evaluate the effectiveness of an endoscopic technique for harvesting the greater saphenous vein for aortocoronary bypass grafting. We hypothesized that the endoscopic technique would minimize the risk of postoperative wound complications. From May 1997 to July 1998, we used an endoscopic technique to harvest the greater saphenous vein in 50 patients who underwent aortocoronary artery bypass grafting. Twenty-five of the patients had an increased risk for wound complications due to preexisting diabetes, obesity, peripheral vascular disease, or lymphedema. The average duration of the procedure was 39 minutes (range, 11 to 70 minutes). The average length of the harvested vein was 58 cm (range, 25 to 85 cm). We made an average of 2.5 incisions per patient (range, 1 to 5 incisions), and the average incision length was 7 cm (range, 3 to 10 cm). Two patients (4%) required conversion to an open technique using 5 small incisions. Postoperative complications included 1 wound infection (2%) and 1 small hematoma (2%). Two patients (4%) had minor erythema at the incision site, and 5 patients (10%) had postoperative lymphedema. The most common problem, ecchymosis, was seen in 6 patients (12%). None required repeat hospitalization or reoperation for wound complications. In our study, the endoscopic approach yielded superior cosmetic results, and reduced wound complications and discomfort, compared with traditional methods of vein harvesting. After gaining expertise with this minimally invasive method of vein harvesting, a surgeon can safely remove the saphenous vein in 20 to 30 minutes.

Pilot study on the relationship between personality traits and skin conductivity of specific surface points as measured by Motoyama's apparatus.

This pilot study used Motoyama's electrodermal response-measuring apparatus to test resting skin conductivity from 28 extremity digit surface coordinates of 33 subjects who also were administered the Eysenck Personality Inventory on an alternatively assigned basis for the dimensions of extraversion and neuroticism. Correlations show significant relationships between neuroticism and extraversion raw scores on two of the 14 bilateral finger surface coordinates.

Mobilization of the anterior mitral leaflet for excision of a left ventricular myxoma.

Left ventricular myxomas are extremely rare. We report use of a left atrial approach with mobilization of the anterior mitral valve leaflet to enhance exposure of the subvalvar region and facilitate excision of a left ventricular myxoma entangled within the chordal apparatus, lying between the anterolateral papillary muscle and the left ventricular wall. The detached mitral leaflet was reattached to the annulus with a continuous suture. The tumor was completely excised, thus avoiding a separate transventricular or transaortic approach.

Limited-access coronary artery bypass grafting. The Texas Heart Institute experience.

Limited-access coronary artery bypass grafting, without the aid of cardiopulmonary bypass, is being performed with increased frequency, but its indications are not well defined. To determine the outcome of, and indications for, this procedure, we analyzed our experience with limited-access coronary artery bypass grafting. Between February 1996 and June 1998, 84 patients underwent limited-access coronary artery bypass grafting at our institution. We retrospectively divided these patients into 2 groups: a high-risk group with complex disease and multiple comorbidities (n = 56), and a low-risk group with uncomplicated disease (n = 28). There were 2 perioperative deaths (2%), and both of them occurred in high-risk cases. Early and late complications included myocardial infarction (2 cases), recurrent angina necessitating revascularization (2 cases), and multisystem dysfunction (1 case). Compared with conventional bypass grafting, limited-access coronary artery bypass grafting offered a smaller skin incision, fewer arrhythmias, less blood loss, less need for inotropic drugs, shorter hospitalization, lower cost, and quicker recovery time. Limited-access coronary artery bypass grafting might have a role in treating high-risk patients who have complex disease and require single-vessel bypass. Anastomosis can be challenging, however, if the target coronary artery is small, calcific, or intramyocardial. Moreover, the long-term results are unknown. Therefore, nonselective use of limited-access coronary artery bypass grafting is unjustified.

Concomitant occlusive disease of the coronary arteries and great vessels.

BACKGROUND: Although an increasing number of elderly and high-risk patients, including those with generalized atherosclerosis, are undergoing coronary revascularization, few reports exist regarding the management of patients who have both occlusive disease of the great vessels and coronary artery disease. METHODS: Between 1972 and 1996, 31 consecutive patients (mean age, 56.5 years; 74% men) with multivessel coronary artery disease and symptomatic occlusive disease of the great vessels (25 single-vessel, 80.6%; 6 multiple-vessel, 19.4%) had 40 great vessels reconstructed by transthoracic bypass (n = 17, 42.5%), transthoracic endarterectomy (n = 8, 20%), or extrathoracic bypass (n = 15, 37.5%). All patients had simultaneous coronary artery bypass grafting (mean, 2.6 grafts per patient), and 8 patients had 10 distal carotid bifurcation endarterectomies (6 staged, 4 simultaneous). RESULTS: The early primary patency rate was 100%, and symptoms resolved completely in all 31 patients. There was 1 in-hospital death (3.2%) in a patient who had a respiratory arrest 11 days after operation. Perioperative morbidity included two myocardial infarctions (6.5%) and one opposite-hemisphere, embolic stroke (3.2%). Long-term follow-up of the 30 survivors (167.4 patient-years; mean, 5.6 years per patient) documented 5- and 10-year actuarial survival rates of 88.6% and 60.4%, respectively, with a 100% late brachiocephalic primary patency rate. Ten-year actuarial rates of freedom from the following events were as follows: death, 60.4%; myocardial infarction, 82.5%; stroke, 90.9%; percutaneous transluminal coronary angioplasty or redo coronary artery bypass grafting, 95.2%; and vascular operation or amputation, 78.4%. CONCLUSIONS: Depending on the anatomic distribution of the disease, an integrated approach to great vessel reconstruction that incorporated transthoracic and extrathoracic approaches and techniques of endarterectomy and bypass resulted in few adverse outcomes and excellent long-term patency. Simultaneous revascularization of the great vessels and coronary arteries can produce immediate and long-term, symptom-free outcome with acceptably low operative risk.

Covert neuromuscular activity of the dominant forearm during visualization of a motor task.

This study evaluated specific covert neuromuscular activity during a silent visualization exercise. 30 subjects participated in a dual-baseline single-subject procedure. The experimental test condition required the subjects to visualize themselves squeezing a hand-size rubber ball as tightly as possible for 1 min. In the comparison test condition, subjects were asked to imagine the 'sun setting on the horizon' for 1 min. Visualization of the motor task brought about significant (p <.05) increases in dominant forearm EMG (microV) and heart-rate activity (bpm) from rest to the experimental test condition. Nondominant forearm activity showed no significant changes from rest to either test condition, and heart-rate activity (bpm) showed no significant change from rest to the comparison visualization task.

Is an integrated approach warranted for concomitant carotid and coronary artery disease?

BACKGROUND: The management of patients with severe, concomitant coronary and carotid artery occlusive disease is controversial. METHODS: Between 1975 and 1996, 512 patients (mean age, 64.9 years; 70% male) were admitted for coronary revascularization; 316 (61.7%) had asymptomatic, severe carotid disease (stenosis > 70%) and 196 (38.3%) had symptomatic carotid disease (159 [31.1%] with transient ischemia and 37 [7.2%] with completed stroke). In group 1, coronary revascularization and carotid endarterectomy were simultaneously performed in 255 patients (49.8%) with unstable angina. In group 2 (staged approach), carotid endarterectomy was performed before coronary revascularization in 257 patients (50.2%) without unstable angina. RESULTS: Before 1986, the incidence of stroke and death was greater in group 1 (n = 149) than in group 2 (n = 156) (14 [9.4%] versus 4 [2.6%]; p < 0.01). Since 1986, outcomes in group 1 (n = 106) and group 2 (n = 101) have been similar for stroke (2 [1.9%] versus 2 [2.0%]), death (4 [3.8%] versus 3 [3.0%]), and myocardial infarction (4 [3.8%] versus 5 [5.0%]). Significant univariate and multivariate predictors of adverse outcome were primarily heart-related (reoperation, intraaortic balloon use, ejection fraction < 0.50, and angina grade 4 for death; age > 70 years and congestive heart failure for stroke). CONCLUSIONS: Despite highly selected populations, contemporary surgical results do not indicate that staged treatment of severe, concomitant coronary and carotid artery occlusive disease has an advantage over simultaneous treatment. Advances in myocardial protection and perioperative hemodynamic management may account for the low incidences of stroke and death in these operations.

Celiac compression syndrome: tailored therapy based on intraoperative findings.

BACKGROUND: The role of surgical treatment for the relatively rare celiac artery compression syndrome remains controversial. We used a tailored operative approach based on intraoperative findings. STUDY DESIGN: We retrospectively reviewed operative and follow-up data from the seven patients at our institution who underwent tailored operative intervention for celiac artery compression syndrome during a 15-year period. RESULTS: In all patients, decompression of the celiac axis was accomplished by division of the sympathetic neural fibers and the median arcuate ligament. In five cases in which intraoperative evaluation demonstrated compromised celiac artery flow after decompression, revascularization was also performed: three patients underwent an aortoceliac bypass, which was performed with a polytetrafluoroethylene graft in two cases and a vein graft in one case; the fourth patient had an angioplasty using a knitted polyester fiber patch, and the fifth patient underwent aortic reimplantation of the celiac artery. The tailored operative approach (decompression alone or with revascularization) for celiac artery compression syndrome, determined on the basis of intraoperative findings, provided complete (immediate and long-term) relief of preoperative symptoms in all seven patients. CONCLUSIONS: The tailored approach to operative intervention for celiac artery compression syndrome, which is based on individual operative findings, offers patients an excellent chance for immediate and long-term freedom from symptoms.

Covert speech behavior during a silent language recitation task.

This study tested the prediction that covert speech behavior measured electromyographically from the lips is significantly more prominent during a brief silent-language recitation task than a brief nonlanguage visualization task. Subjects were 20 right-handed, adult volunteers who agreed to participate. Subjects were tested in a multiple-baseline reversal design following an ABAB procedure whereby A1 and A2 were 30-sec. rest periods. B1 and B2 were alternatively assigned 30-sec. silent-language recitation and visualization test periods, respectively. Subjects' dorsal lips and nondominant forearm EMG measures were taken during resting baseline and testing conditions. In addition, subjects' skin surface temperature and heartrate were measured during the rest and test conditions. For the silent-language task, subjects were asked to recite 'mentally' the Pledge of Allegiance to the flag. Subjects were instructed to 'imagine seeing' the American flag for the visualization task. Subjects' mean lip EMG activity increased significantly from rest to the silent-language recitation task, while no significant change in mean lip EMG was observed from rest to the visualization condition.

Carotid endarterectomy. Results in asymptomatic and symptomatic patients.

Objective evidence of the benefit of carotid endarterectomy in preventing stroke and its significant sequelae has recently been demonstrated by prospective trials. The salutary results depend on meeting strict operative outcome criteria as established by the American Heart Association. We retrospectively analyzed 265 consecutive carotid endarterectomies performed in 248 patients during 1 year at our institution. The perioperative mortality rate was 0; late mortality occurred 6 months postoperatively in 1 of 2 patients who experienced a perioperative stroke. The combined perioperative mortality and stroke rate was 0.8%. The combined mortality and stroke rate in patient subgroups was 0.7% (1/151) for asymptomatic patients, 1.6% (1/64) for symptomatic patients who had presented with a transient ischemic attack, and 0% (0/50) for symptomatic patients who had presented with a completed stroke. We conclude that the objective postoperative benefits of carotid endarterectomy in treating extracranial cerebrovascular disease can be achieved with low perioperative patient morbidity.

Covert speech behavior during video-viewing tasks with and without an overt speech soundtrack.

This pilot study tested the prediction that covert speech activity measured by lip EMG(mu v) is significantly greater during the presentation of prerecorded speech than in a 'speechless' video-viewing test condition and conditions of rest. A single-subject multiple-baseline design was used and nondominant forearm EMG(mu v) activity was also measured for comparison purposes. Analysis showed a significant increase in lip EMG(mu v) activity in 1 out of 2 rest-to-test conditions involving the presentation of prerecorded overt speech. There was no significant difference in the subjects' mean lip EMG(mu v) values across 3 test conditions, however.

EMG and cardiovascular responses to emotionally provocative photographs and text.

Previous studies on the psychophysiology of human emotion have repeatedly shown general and occasionally specific facial EMG (mu v) and covert cardiovascular response relationships to emotionally provocative photographs. Less clear are the relationships between psychophysiological response indices measured during the silent reading of emotionally charged versus emotionally neutral text. In this study, 12 adult subjects were presented two emotionally loaded color and black-and-white photographs and two brief newspaper articles, one emotionally charged and the other emotionally neutral in content. Each independent stimulus was presented for 1 min., preceded by a rest according to a multiple baseline-reversal design. Subjects evaluated each pictorial and textual stimulus condition according to adjective dimensions on 7-point rating scales. Mean values for corrugator supercilii EMG (mu v), upper trapezius EMG (mu v), surface temperature (degrees F), and heart rate (bpm) measured by finger photoplethysmography were measured during each rest and test period. Significant increases in the subjects' mean corrugator supercilii EMG (mu v) measures were observed during all color and black-and-white photograph presentations for both emotional and neutral content. As predicted, the subjects' mean corrugator supercilii EMG (mu v) measures increased significantly while silently reading text with an obvious unpleasant emotional tone. A significant positive relationship was observed between the subjects' mean ratings and mean corrugator EMG (mu v) difference values for the emotionally loaded color photographs.

Long-term results of the surgical management of symptomatic chronic intestinal ischemia.

We analyzed our surgical experience in 20 patients who underwent revascularization procedures for symptomatic chronic intestinal ischemia caused by atherosclerosis. The group comprised 17 women and 3 men, with an age range of 25 to 71 years (mean 58.6 years). Sixteen patients had postprandial abdominal pain, and 4 had pain not related to eating. The average weight loss was 23.8 lb. Malabsorption and diarrhea were present in 8 patients. The duration of the symptoms was from 4 to 46 months (mean 13.4 months). One patient presented with acute intestinal ischemia following balloon angioplasty reocclusion of a stenotic celiac artery, and 3 underwent surgery for stenosis of a previously placed graft. Five patients had single mesenteric artery involvement, 10 had double-artery involvement, and 5 had significant occlusion in all 3 mesenteric arteries. The major arteries were revascularized whenever technically possible; therefore, 36 arteries were revascularized in 20 patients. Bypass grafts were done in 27 vessels, reimplantation in 7, and endarterectomy with patch angioplasty in 2. The saphenous vein was used in 12 vessels, polytetrafluoroethylene grafts in 8, dacron in 6, and inferior mesenteric vein in 1. The type of revascularization or graft utilized did not affect long-term patency. Two patients had early graft thrombosis and required intestinal resection. All patients survived the operation. At a mean follow-up of 36 months, all 20 patients were alive and asymptomatic with regard to their abdominal complaint. Ten patients (50%) underwent postoperative abdominal angiography; all the grafts were patent.(ABSTRACT TRUNCATED AT 250 WORDS)