Twin lossy mode resonance on a single D-shaped optical fiber.

This Letter presents the fabrication of dual lossy mode resonance (LMR) refractometers based on titanium dioxide (TiO2) and tin oxide (SnO2) thin films deposited on a single side-polished D-shaped optical fiber. For the first time, to the best of our knowledge, two independent LMRs are obtained in the same D-shaped optical fiber, by using a step-shaped nanostructure consisting of a first section of TiO2 with a thickness of 120 nm and a second section with a thickness of 140 nm (120 nm of TiO2 and 20 nm of SnO2). Each section is responsible for generating a first-order LMR with TM-polarized light (LMRTM). TiO2 is deposited by atomic layer deposition and SnO2 by electron-beam deposition. The theoretical results show that the depth of each of the resonances of the dual LMR depends on the length of the corresponding section. Two experimental devices were fabricated with sections of different lengths, and their sensitivities were studied, achieving values ∼4000nm/refractiveindexunit (RIU) with a maximum of 4506 nm/RIU for values of the SRI between 1.3327 and 1.3485.

High sensitive refractometers based on lossy mode resonances (LMRs) supported by ITO coated D-shaped optical fibers.

Tin doped indium oxide (ITO) coatings fabricated onto D-shaped optical fibers are presented as the supporting medium for Lossy Mode Resonances (LMRs) generation. The characteristic geometry of ITO-coated D-shaped optical fibers enables to observe experimentally LMRs obtained with both TM and TE polarized light (LMR(TM) and LMR(TE)). This permits to obtain a maximum transmission decay of 36 dB with a LMR spectral width of 6.9 nm, improving that obtained in previous works, where the LMRs were a combination of an LMR(TM) and an LMR(TE). Surrounding medium refractive index (SMRI) sensitivity characterization of LMR(TM) has been performed obtaining a maximum sensitivity of 8742 nm/RIU in the range 1.365-1.38 refractive index units (RIU) which overcomes that of surface plasmon resonance-based optical fiber devices presented in recent works.

Experimental demonstration of lossy mode resonance generation for transverse-magnetic and transverse-electric polarizations.

This Letter, presents the fabrication of lossy mode resonance (LMR) devices based on titanium dioxide (TiO2)/ poly(sodium 4-styrenesulfonate) (PSS) coatings deposited on side-polished D-shaped optical fibers. TiO2 thin films have been obtained by means of the layer-by-layer (LbL) self-assembly technique. LbL enables us to produce smooth and homogeneous coatings on the polished side of the fiber. This permits us to couple light from the waveguide to the TiO2-coating/external medium region at specific wavelength ranges. The generation of LMRs depends on the coating thickness, so that thicker coatings can produce more resonances. LMRs are sensitive to the external medium refractive index, which allows its utilization as refractometers. The characteristic D-shaped architecture of the devices employed in this Letter enables us to distinguish TE and TM polarizations, which had not been possible before with regular optical fibers due to their cylindrical symmetry. The results presented here show for the first time the experimental demonstration of the generation of LMRs produced by both TM and TE polarizations. More specifically, for these TiO2/PSS thin films, the TM and TM modes of the LMRs show a wavelength shift of 226 nm for the first-order LMR and 56 nm for the second-order LMR.

High sensitive and selective C-reactive protein detection by means of lossy mode resonance based optical fiber devices.

This work presents the development of high sensitive, selective, fast and reusable C-reactive protein (CRP) aptasensors. This novel approach takes advantage of the utilization of high sensitive refractometers based on Lossy Mode Resonances generated by thin indium tin oxide (ITO) films fabricated onto the planar region of d-shaped optical fibers. CRP selectivity is obtained by means of the adhesion of a CRP specific aptamer chain onto the ITO film using the Layer-by-Layer (LbL) nano-assembly fabrication process. The sensing mechanism relies on resonance wavelength shifts originated by refractive index variations of the aptamer chain in presence of the target molecule. Fabricated devices show high selectivity to CRP when compared with other target molecules, such as urea or creatinine, while maintaining a low detection limit (0.0625mg/L) and fast response time (61s). Additionally, these sensors show a repetitive response for several days and are reusable after a cleaning process in ultrapure water.

Surgical treatment of aneurysm of the ascending aorta with aortic insufficiency and marked displacement of the coronary ostia.

Six patients with a large aneurysm of the ascending aorta involving the root of the aorta and severe aortic valve insufficiency owing to marked annular dilatation were treated by replacement of the ascending aorta and aortic valve with a composite unit. It was also necessary to transpose the origin of the coronary arteries with the use of saphenous vein grafts. In 3 patients, the aneurysm was due to a chronic dissection. In one patient, the aneurysm extended beyond the arch of the aorta. There were no operative deaths. One patient died suddenly of pulmonary emboli 11 months after surgery. The remaining 5 patients are doing well, 5 months to 4 years postoperatively.

Myocardial revascularization for the patient with drastic impairment of function of the left ventricle.

The results with medical treatment of the patient with coronary artery disease and marked impairment of left ventricular function have been poor. Of 79 patients deemed operable with an ejection fraction of 0.2 or less, only 17 (22 per cent) were alive according to an acturial curve 5 years later. We believed that surgery might offer a better outlook for these critically ill patients. Therefore, since 1969, 140 patients with an injection fraction of 0.2 or less were treated by myocardial revascularization alone, with 31 hospital deaths. Actuarial curve reveals that at 6 years, 59 per cent of the surgically treated patients are alive, and only 22 per cent treated medically are alive at 5 years. It is concluded that if the operative mortality rate is low enough, surgery enhances the survival of patients who have drastic impairment of left ventricular function. These patients are significantly improved clinically.

Surgical correction of severe mitral prolapse without mitral insufficiency but with pronounced cardiac arrhythmias.

Despite what was considered adequate pharmacological treatment, the condition of six patients with severe mitral valve prolapse but with trivial or no mitral regurgitation deteriorated. These patients had marked weakness, chest pain, dyspnea, and arrhythmias. Because these patients found their condition to be intolerable, the prolapsed mitral valve was repaired. Electrocardiography, treadmill stress testing, and left ventirculography performed following operation showed complete repair of the valve and significant improvement over the preoperative findings in all six patients. Repair of the floppy mitral valve did not eradicate all abnormalities; however, it did significantly improve the chest pain, weakness, dyspnea, and arrhythmias in all six patients. Five patients no longer require any medication. The prolapsed mitral valve contributed significantly to the symptoms and arrhythmias, but it could not have been the sole cause for these patients' signs and symptoms. With complete correction of the prolapse in all six patients, few of the signs and symptoms of the disease persisted. Repair of severe mitral valve prolapse without mitral regurgitation is recommended only for those patients who continue to be severely symptomatic from chest pain, dyspnea, or ventricular arrhythmias after an extensive trial of adequate medical therapy.

Cardiac operation without hypothermia for the patient with cold agglutinin.

Recently, a new technique for myocardial protection that does not rely on hypothermia has been reported. In this method, the heart is continuously perfused with normothermic hyperkalemic blood cardioplegia during the cross-clamp period. Cardiac arrest is achieved and maintained using high levels of potassium. Hypothermia is not part of this technique; thus, the danger of hypothermia can be avoided in the patient with cold agglutinin disease without compromising myocardial protection. This communication reports our experience using retrograde continuous normothermic blood cardioplegia in one patient with potent cold agglutinins and severe coronary artery occlusive disease. This patient experienced an uneventful operative and postoperative course and remains asymptomatic, now more than two years after operation.

Probability of valve repair for pure mitral regurgitation.

The advantages of mitral valve repair are well established. Unfortunately, not all valves can be repaired. This presents a dilemma for the surgeon in terms of advising the patient as to the timing of operation and in decision making during operation. Patients requiring correction for pure mitral regurgitation are a heterogeneous group. By classifying the patients according to the cause of mitral regurgitation and the pathologic anatomy, we determined patterns of repair in our surgical practice for 100 consecutive patients with pure mitral regurgitation treated from January 1990 through June 1991. Patients with degenerative valve disease that spares the central portion of the anterior leaflet were likely to undergo valve repair (22/24), whereas those patients with involvement of the central portion of the anterior leaflet were likely to require replacement (15/17). This disparity may be related to the techniques of repair that were used and has spurred us to use other techniques when faced with this problem. Patients with ischemic mitral regurgitation caused by anulus dilatation were likely to undergo repair (15/17), whereas patients with ruptured papillary muscle usually underwent valve replacement (8/9). Operative mortality in this series was accurately predicted by the Parsonnet risk score. Combining knowledge of the expected operative risk and the likelihood of valve repair based on anatomic and pathologic considerations should allow the surgeon to better inform patients of their surgical options.

Surgical treatment of mitral insufficiency secondary to coronary artery disease.

From 1970 to 1978, 61 patients were operated upon for mitral insufficiency secondary to coronary artery disease. These patients were between 44 and 71 years of age and all were in Class III or IV of the New York Heart Association Classification. The left ventricular end-diastolic pressure was 15 mm Hg or more in 32 of the 39 patients in whom it was measured. Twenty-four of 31 patients in whom right heart catheterization was performed had a systolic pulmonary artery pressure of 50 mm Hg or greater. All 61 patients had myocardial revascularization, 52 had repair of the mitral valve, and nine had mitral valve replacement. There were five hospital deaths in these 61 patients. Among the nine patients with a preoperative ejection fraction of 0.1 to 0.2, there were two hospital deaths; among the 20 patients with a preoperative ejection fraction of 0.25 to 0.40, there were two hospital deaths; and among the 32 patients with a preoperative ejection fraction of 0.45 to 0.70, there was only 1 hospital death. For those patients with repair and revascularization, the survivability was 81% at 7 years. In the patients with repair and myocardial revascularization, the incidence of peripheral embolization was 0.5% per patient-year.

Surgical treatment of Candida endocarditis.

Case reports from a group of 15 patients with Candida endocarditis seen and treated at the Los Angeles-University of Southern California Medical Center between 1960 and 1974, together with a survey of other reported cases, serve to re-emphasize the importance of early diagnosis of this disease and lead to certain conclusions regarding its treatment. With medical or surgical treatment alone, the mortality for Candida endocarditis is 82 per cent. With surgery and medical treatment combined, the mortality is 20 percent. It is important to institute medical treatment as soon as diagnosis of Candida endocarditis is made and surgery must be performed as soon as possible, preferably within 24 to 48 hours or, at most, a few days after the patient has left the hospital. Close observation of the patient after discharge is important.

Rapid sustained recovery after cardiac operations.

After successful cardiac operations in the early 1980s the most common causes of prolonged hospitalizations were noncardiac disorders. We prevented or quickly corrected these noncardiac disorders after operations in succeeding patients and observed in the following 2 years that the shortest postoperative stays in the hospital were followed by the fewest rehospitalizations. In 240 consecutive patients the median length of hospital stay after operation was 4 days. The operations included coronary artery bypass procedures, aortic valve replacements, and mitral valve operations. Six patients (2.5%) were rehospitalized within 6 months after discharge and five patients (2.1%) were rehospitalized 6 to 24 months after discharge: Longer initial hospitalizations would not have prevented rehospitalizations. Forty of the 240 patients were discharged on the third postoperative day or earlier (one patient). None died or were rehospitalized in the following 2 years. Prevention or quick correction of noncardiac disorders allowed rapid recovery after heart operations, and rapid recovery indicated that health would be maintained.

Repeat aortocoronary bypass grafting. Early and late results.

Seventy-nine patients underwent repeat myocardial revascularization between March 1971 and January 1977. The initial procedure was performed at the St. Vincent Medical Center, Los Angeles, in 70 (2.0 percent) of 3,526 patients undergoing surgery for coronary arterial disease and in nine more patients was performed at other hospitals; the second operation followed the first procedure at an interval of from three weeks to 78 months. Five deaths (6 percent) occurred while patients were hospitalized, and six deaths (8 percent) occurred later. Two of the six later deaths were from noncardiac causes. Complications were not different from those that occurred during primary procedures. Thirty-six (60 percent) of 60 patients undergoing repeat surgery since 1973 did not receive any transfusions of blood during or after surgery. Of 48 patients followed-up for periods ranging from 12 to 70 months after the second operation, angina was completely relieved in 18 patients (38 percent), improved in 16 patients (33 percent), unchanged in 11 patients (23 percent), and worse in three patients (6 percent).

Surgery for mitral and tricuspid insufficiency associated with secundum atrial septal defect.

Pure mitral insufficiency associated with secundum atrial septal defect is not an unusual finding. Thirteen patients with significant mitral insufficiency and an associated secundum defect were operated upon. Two of these patients also had severe tricuspid insufficiency. The mitral valve was repaired in 12 patients and replaced in one. The tricuspid valve was reapired in the two patients with associated tricuspid insufficiency. There were two early deaths due to mediastinitis and one late death due to a cerebral embolus in the only patient who had valve replacement; this patient died 3 years after the operation. It is concluded that mitral and tricuspid valve repair should be performed for patients with significant mitral and tricuspid insufficiency associated with atrial septal defect of the secundum variety. Replacement of the values should be avoided if possible.

Forward angiography in the identification of vegetations in tricuspid endocarditis.

A patient with staphylococcal endocarditis of unknown valvular location and resistant to antibiotic therapy was studied in order to localize the site of infection prior to cardiac surger. The injection of contrast material into the right atrium visualized tricuspid vegetations which were confirmed at surgery. In such situations, forward angiographic studies constitute a safe, simple, and potentially diagnostic procedure which avoids the hazards of advancing a catheter across an infected valve.

Prediction of long-term survival by preoperative exercise testing in patients with depressed ejection fraction undergoing myocardial revascularization.

Ejection fraction is a major determinant of morbidity and mortality for patients with ischemic heart disease. Patients with an ejection fraction of 0.40 or less are generally recognized as having a poorer prognosis than those patients with an ejection fraction of 0.50 or better and remain a heterogeneous group. It would be useful if patients with a favorable surgical prognosis could be identified preoperatively. Fifty-five patients who underwent coronary artery bypass grafting and had an ejection fraction less than 0.40 (mean of 0.23 +/- 0.07 standard deviation) were studied by catheter measurement of pulmonary arterial pressure and radionuclide left ventriculography. Heart rate, systemic blood pressure, pulmonary artery pressures, cardiac output, and ejection fraction were measured, at rest, after nitroglycerin was given intravenously and with supine bicycle exercise. Forty-seven patients who had follow-up longer than 4 years were divided into two groups according to their life status (alive or dead) 4 years after operation. Measured variables of exercise stress tests and clinical characteristics were entered into factor analysis to obtain a cardiac function factor score for predicting the life status after 4 years. The cardiac function factor score was highly loaded by stroke index (rest, nitroglycerin), cardiac index (exercise), systemic vascular resistance index (exercise), and history of congestive heart failure. The cardiac function factor provided a predictive value superior to that of any individual variable. By dividing the patients into two groups by cardiac function factor score, the actuarial 5-year survival was 72% versus 17% for good and poor prognosis groups, respectively (p < 0.0001). Preoperative exercise stress testing data integrated by factor analysis provide a predictive tool for patients with a low ejection fraction.

Resection of postinfarction left ventricular aneurysm with and without revascularization.

Twenty-four patients had resection of their ventricular aneurysm and 29 had resection plus revascularization. Sixty percent of the patients received no blood in the heart lung machine during surgery or at any time during hospitalization. One of 24 patients with ventricular resection and two of 29 patients with resection plus revascularization died during hospitalization, for an overall mortality of 5.7%. Fifty of the 53 patients had an ejection fraction of 0.4 or less and 23 of these had an ejection fraction of 0.2 or less. Survival rate was 75.5% at four years for all 53 patients compared to only 12% of patients alive at five years with medical treatment. For the patient with a large ventricular aneurysm, resection and myocardial revascularization can be performed with a low risk even for the patient with poorly functioning residual myocardium.

A further look at tricuspid annuloplasty.

Is it necessary to replace the tricuspid valve or insert a tricuspid ring for pure tricuspid insufficiency, or is repair satisfactory? In 96 of 113 patients with pure tricuspid insufficiency the tricuspid valve was repaired by converting the incompetent three-leaflet valve into a two-leaflet one. To avoid liver damage in these critically ill patients, the inferior caval tie was omitted during the open-heart procedure. There have been 5 deaths in the last 51 consecutive operations. Three patients developed recurrent tricuspid insufficiency secondary to failure of the mitral repair or replacement. It is concluded that tricuspid repair for pure tricuspid insufficiency is a simple and excellent method for treating severe, pure tricuspid insufficiency.

A useful instrument for aortocoronary bypass operations.

A punch biopsy forceps is described that is used to make openings in the aorta for anastomosing one end of a saphenous vein graft to the ascending aorta. It can be very successful in myocardial revascularization when there is severe calcification of the aortic wall.

Thirteen years' experience with the Kay-Shiley disc valve for tricuspid replacement in Ebstein's anomaly.

From August, 1965, to November, 1974, 11 patients underwent operation for Ebstein's anomaly. In 1 patient operated on on August 16, 1965, the early Kay-Shiley disc valve was used. In the remaining 10 patients, the Kay-Shiley muscle guard valve was inserted. This valve was designed to prevent the prosthesis from encroaching on the right ventricle, thereby increasing the flow around the disc. One patient with a history of Wolff-Parkinson-White syndrome died of dysrhythmia on the first postoperative day. The other 10 patients have been followed from 4 to 13 years (mean, 6 years 2 months) after operation. Seven patients are working full-time without difficulty, 2 are housewives, and 1 attends school. All patients have improved at least one class in the New York Heart Association Functional Classification.