Acoustic metasurfaces with Frieze symmetriesa).

Frieze patterns follow a set of tiling instructions including reflection, rotation, and translation, and tile the infinite strip. Many metamaterials function due to the underlying symmetry, and its strategic breaking, of their constituent sub-structures that allow tailoring of the dispersion of modes supported by the structure. We design, simulate, and experimentally characterize seven one-dimensional acoustic metasurfaces whose unit cells each belong to one of the distinct Frieze groups.

Graded Quasiperiodic Metamaterials Perform Fractal Rainbow Trapping.

The rainbow trapping phenomenon of graded metamaterials can be combined with the fractal spectra of quasiperiodic waveguides to give a metamaterial that performs fractal rainbow trapping. This is achieved through a graded cut-and-project algorithm that yields a geometry for which the effective projection angle is graded along its length. As a result, the fractal structure of local band gaps varies with position, leading to broadband "fractal" rainbow trapping. We demonstrate this principle by designing an acoustic waveguide, which is characterised using theory, simulation and experiments.

Multi-scale bullseye antennas.

We design, simulate and experimentally characterize a multi-scale bullseye antenna for the broadband manipulation of microwaves. The device achieves far-field beam-forming via tailored diffraction at the interface between two concentric bullseye geometries, with near-field energy concentration resulting from the overlap of the diffracted beams. This article is part of the theme issue 'Wave generation and transmission in multi-scale complex media and structured metamaterials (part 1)'.

Acute pancreatitis after cardiac transplantation and other cardiac procedures: case-control analysis in 24,631 patients.

Previous series have identified an increased risk of developing acute postoperative pancreatitis in heart transplant recipients and other cardiac surgical patients, and some suggest that mortality is significantly increased when pancreatitis occurs in the transplant setting. We conducted a retrospective case-control analysis of adult patients undergoing orthotopic heart transplant or other cardiac procedures from April 1985 through June 1996 at our medical center. Specific risk factors for outcome were assessed including low cardiac output, intra-aortic balloon pump usage, exogenous calcium repletion, immunosuppression, cytomegalovirus infection, cholelithiasis, prior pancreatitis, and Acute Physiology and Chronic Health Evaluation (APACHE) II scores. There was a 30-fold increase in the incidence of pancreatitis in the heart transplant group [12 of 394 (3%) vs 27 of 24,237 (0.1%); P < 0.01]. Compared with the nontransplant cardiopulmonary bypass patients, the transplant patients experienced a statistically significant increased incidence of immunosuppression and three or more risk factors. Transplant patients with pancreatitis demonstrated a significant increase in APACHE II scores and the incidence of three or more risk factors compared with their transplant control group. Patients undergoing nontransplant cardiac procedures and developing pancreatitis had significantly increased cross-clamp times, incidence of low cardiac output, APACHE II scores, and incidence of three or more risk factors compared with their nontransplant cohort. In conclusion, there is a significant increase in the incidence of pancreatitis after orthotopic heart transplant compared with other cardiac procedures. Analysis demonstrates the additive effect of multiple individual risk factors. Immunosuppression confers significant additional risk for pancreatitis in the orthotopic heart transplant patient.

Ventricular aneurysmectomy. A 25-year experience.

OBJECTIVE: This study determined predictors of operative survival and improved long-term outcomes in patients undergoing ventricular aneurysmectomy. SUMMARY BACKGROUND DATA: Since the first successful repair of ventricular aneurysm in 1958, refined technique and improvement in perioperative care have been introduced to lower morbidity and mortality. METHODS: The authors reviewed their institutional experience from 1968 through 1993 in treating 523 patients who underwent ventricular aneurysmectomy. RESULTS: Overall operative mortality was 8% and overall median survival was 128 months. Contractility grade, age, and year of operation were predictors of operative mortality and of improved long-term survival. Type of aneurysm repair was not a strong predictor of operative mortality or improved long-term survival. CONCLUSIONS: Ventricular aneurysmectomy can be performed safely using one of a number of established techniques, although operative mortality and long-term survival may not depend on the techniques used.

Tumor emboli from lung neoplasms involving the pulmonary vein.

Systemic tumor embolization during pulmonary resection for lung neoplasms is an uncommon but potentially catastrophic complication. In recent months, two patients undergoing pulmonary resection for bronchogenic carcinoma were found at operation to have tumor extending into a pulmonary vein. Both patients had systemic tumor embolization, one with a fatal outcome because of occlusion of the superior mesenteric artery. The possibility of systemic tumor embolization should be considered in patients with large, central tumors and particularly those that abut the pulmonary veins. The implications of such pulmonary vein involvement is reviewed, and an algorithm for postoperative evaluation and management of these patients is presented.

MMPI interpretation of psychiatric inpatients: caution in making inferences about concentration and memory.

The relation of specific MMPI scores to attention, concentration, and memory was assessed in an inpatient psychiatric sample diagnosed by DSM-III-R criteria as having schizophrenia, chronic undifferentiated type (n = 22); schizophrenia, paranoid type (n = 17); and schizoaffective disorder (n = 20). MMPI indices that are used widely to infer cognitive efficiency--including Scales 2 (Depression), 8 (Schizophrenia), SC-PT, D4 (Mental Dullness), SC2A (Lack of Ego Mastery, Cognitive), PSY (Psychoticism) and ORG (Organic Symptoms)--were investigated in relation to actual performance on Digit Span and subtests of the Wechsler Memory Scale (WMS, Russell's Revision). Weak correlations emerged (maximum r = .31, p less than .05), which suggests that scores on these MMPI measures may not provide a reliable basis for inferring attention and memory functioning.

Videothoracoscopy: improved technique and expanded indications.

Current videoendoscopic technology and percutaneous techniques of exposure and dissection have been successfully applied to abdominal surgery with favorable results. Application of this technology to our practice of thoracoscopy is the basis of this report. Videothoracoscopy has been performed in 39 patients for the following indications: chronic pleural effusion, interstitial lung disease, mediastinal lymphadenopathy in lung cancer, persistent air leak after decortication, mediastinal mass, recurrent spontaneous pneumothorax, hydropneumothorax with persistent air leak, and pleural-based mass. The technique we employ includes lateral decubitus positioning and double-lumen endotracheal intubation with ipsilateral lung collapse. The videoscope, retractors, and instruments are introduced through separate 10-mm incisions. Percutaneous manipulation of instruments and the videoscope is guided by images produced on television screens without dissection, and if resection is performed, the incision is enlarged to allow specimen retrieval. Procedures performed using this technique include pleural biopsy, partial pleurectomy, lysis of adhesions, lung biopsies, staging lymph node biopsy, lung nodule biopsy, pleural-based mass resection, and mediastinal mass biopsy and resection. This videoendoscopic technique greatly improves visualization of thoracic anatomy, facilitating thoracoscopy and enhancing exploration of the chest. It is preferred over conventional thoracoscopy and, in some patients, reduces the magnitude of operation by avoiding thoracotomy.

Acute traumatic aortic rupture: intravascular US findings.

Traumatic aortic rupture is a lethal injury that requires immediate diagnosis and surgical repair. The authors report a case of acute aortic rupture in which aortography demonstrated a subtle intimal discontinuity at the cephalic margin of the aortic spindle. Intravascular ultrasound (US) imaging of the aorta demonstrated a mural flap and a small, contained hematoma. Intravascular US may have a role in enabling confirmation or clarification of subtle aortic abnormalities.

Distant graft procurement for combined heart and lung transplantation using pulmonary artery flush and simple topical hypothermia for graft preservation.

Although combined heart and lung transplantation has great potential for improving survival and rehabilitation in selected patients with pulmonary vascular disease, the lack of suitable donor organs has restricted the number of operations performed. We report a heart and lung transplantation operation for Eisenmenger's syndrome in which distant donor graft procurement was used with a simple system for preservation.

Myoventriculoplasty and neoventricle myograft cardiac augmentation to establish pulmonary blood flow. Preliminary observations and feasibility studies.

In 10 dogs, a latissimus dorsi muscle (myograft) was neuroelectrically stimulated at 120 cycles/min for as long as 80 days. The higher thresholds and multiple lead penetrations required of direct muscle stimulation for muscle conditioning were avoided. Vascular delay and protective wrapping of the myograft in four dogs resulted in rapid seroma and fibrous sheath formation, which precluded further study. Of the six other myografts that were stimulated, two were used as functional right ventricular myoventriculoplasties and four were employed as neoventricle myografts with inflow and outflow valved conduits that were used to provide total pulmonary blood flow. Myoventriculoplasty produced functional enlargement of the right ventricle with synchronously contractile muscle. Neoventricles provided hemodynamically stable total pulmonary blood flow for as long as 20 hours, until internal chamber thrombus formed. Transpulmonary blood pressure generation by the neoventricle was found to be programmable up to physiologic systemic pressures by modulation of chamber preload and burst stimulation frequency at 50 msec intervals, delivered 120 times per minute. Synchronization capabilities for implantable burst pulse generators would further improve the efficacy of these myograft techniques designed to augment or supplant ventricular function, particularly to provide transpulmonary blood flow at programmable pressures.

An assessment of Nva2-cyclosporine in primate cardiac transplantation.

The immunosuppressive potency, hepatotoxicity, and nephrotoxicity of Norvaline2-cyclosporine (Nva2-CsA), an analog of cyclosporine (CsA), were tested in a primate cardiac transplant model. After orthotopic cardiac transplantation in cynomolgus monkeys, immunosuppression was maintained with 16 mg/kg/day of either CsA or Nva2-CsA given intramuscularly in two divided daily doses. Immunosuppression was augmented with i.m. methyl-prednisolone, 1.0 mg/kg/day, which was tapered weekly by .1 mg/kg/day to a maintenance dose of .1 mg/kg/day. A group of 6 untransplanted monkeys were treated for a year with this dose of either CsA or Nva2-CsA and steroids. Renal biopsies were performed at one year. Among the transplanted monkeys, mean survival was 77.3 +/- 73 days for the CsA group and 16 +/- 8 days for the Nva2-CsA group. All 11 animals in the Nva2-CsA group died of cardiac rejection, but only 7 of 10 treated with CsA died of rejection. There was mild hepatic and renal dysfunction in both treatment groups, but no significant difference between groups as judged by blood urea nitrogen, creatinine, total bilirubin, serum glutamic oxaloacetic transaminate, and alkaline phosphatase. Cyclosporine levels were significantly higher in the CsA group. There were important morphological changes in both groups on histological examination of the kidneys, with proximal tubular vacuolation and enlargement of the juxtaglomerular apparatus predominating. It is concluded that Nva2-CsA is a less effective immunosuppressant than CsA when given parenterally in equal doses.

Intravenous prostaglandin E1, cold crystalloid flush and topical hypothermia for cardiopulmonary graft preservation.

For no organ is the need more acute than for the lung or heart-lung block. The new improved "freezing" technique with simultaneous use of intravenous prostaglandin E1 will result in reliable and adequate heart-lung block preservation. The lungs are flushed with high-volume (60 ml/kg), low-pressure (less than 20 mmHg), low-flow (15 ml/kg/min), using modified Euro-Collins solution (added 12 Meq/L of MgSO4 and 65 ml/L of 50% Dextrose). Additional topical cooling has been achieved by cold Physiosol and the excised graft is then placed in a plastic bag filled with Physiosol. This static hypothermia has been successfully used with extended ischemia times of more than six hours in primates and almost four hours in man. Forty heart-lung transplantations have been done from March 1981 to September 1986 and nine of them have been performed using this "freezing" technique with prostaglandin E1. Distant graft procurement has been used twice for heart-lung transplantation. All nine most recent patients who have received the graft harvested with this new "freezing" technique are doing well.

Successful six-hour cardiopulmonary preservation with simple hypothermic crystalloid flush.

Combined heart and lung transplantation was performed in 12 cynomolgus or rhesus monkeys. The donor heart was preserved with 10 ml/kg of cold crystalloid potassium cardioplegia. The lungs were preserved by perfusing the pulmonary artery over 4 minutes with 60 ml/kg donor weight of cold Euro-Collins solution modified with 8 mEq/L of MgSO4. For six animals in group A, the heart and lungs were immediately transplanted with a mean ischemic time of 1 hour 54 minutes. For six animals in group B, the heart and lungs were stored in a cold extracellular electrolyte solution at 2 degrees to 3 degrees C and transplantation was delayed, with a mean ischemic time of 6 hours and 15 minutes. Anesthesia and mechanical volume ventilation were continued for 8 hours postoperatively with the Fio2 regulated to 40% and with 2 cm positive end-expiratory pressure. Arterial Po2 was sampled at 1, 2, 3, 4, 6, and 8 hours after removal of the aortic cross clamp. Animal survival and cause of death were recorded. All animals were successfully extubated by 10 hours after transplantation. The mean arterial Po2 for group B was initially depressed (89 mm Hg 1 hour after removal of the aortic cross clamp) but rapidly recovered. The mean Po2 for both groups A and B was 184 mm Hg 8 hours after reperfusion. There was no significant difference in the mean hourly Po2 between groups A and B except for the first hour after reperfusion. One animal in each group died of pulmonary insufficiency in the early postoperative period.(ABSTRACT TRUNCATED AT 250 WORDS)