Ultrafast optical multidimensional spectroscopy without interferometry.

We present here the details of a phase retrieval technique that provides access to multidimensional modalities that are not currently available using existing interferometric techniques. The development of multidimensional optical spectroscopy has facilitated significant insights into electronic processes in physics, chemistry, and biology. The versatility and number of available techniques are, however, significantly limited by the requirement that the detection be interferometric. Many of these techniques are closely related to the vast range of multidimensional NMR spectroscopies, which revolutionized analytical chemistry more than 30 years ago. We focus here on the specific case of two-color multidimensional spectroscopy (analogous to heteronuclear NMR) and discuss the details of an iterative algorithm that recovers the relative phase relationships required to perform the Fourier transformation and find the unique solution for the 2D spectrum. A detailed guide is provided that describes the practical implementation of such algorithms. The effectiveness and accuracy of the phase retrieval process are assessed for simulated one- and two-color experiments. It is also compared with one-color experimental data for which the target phase information has been obtained independently by interferometry. In all the cases, the present algorithm yields results that compare well with the solutions obtained by other means. There are, however, some limitations and potential pitfalls that are identified and discussed. We conclude with a discussion of the potential applications and further advances that may be possible by adopting iterative phase retrieval algorithms of the type discussed here.

Partial inflow occlusion: a neglected technique for treating troublesome aortic leaks.

Most cardiac surgeons occasionally encounter troublesome bleeding from an ascending aortic site and are aware of the potential difficulties associated with repairing this complication. Partial inflow occlusion, as described below, is a simple method of depressurizing the aorta to facilitate suture placement after cardiopulmonary bypass.

Polypropylene suture--is it safe?

Polypropylene suture has steadily gained popularity for use in vascular and cardiac surgical procedures because of its long-term tensile strength and minimal tissue trauma. However, recently some questions have arisen concerning its safety. We recently had two cases of polypropylene fracture, one occurring early and the other late after operation. Comparison and collation of these two cases with other reports leads to the conclusion that polypropylene suture is safe in most situations, but care must be taken to avoid instrumentation trauma and kinking stresses at knots, which probably explain most of the reported cases of polypropylene failure. In addition, polypropylene probably should not be used in graft-to-graft anastomoses in which the continual sawing stresses of two rigid structures appears to lead to an excessive incidence of late suture fracture with resultant false aneurysm formation.

Proximal shunt dissection: a potential problem in carotid endarterectomy.

The use of a shunt routinely, selectively, or not at all in performing carotid endarterectomy is a controversial and thus far unsettled dilemma. We have routinely used a shunt because it allows the operation to be done meticulously and without a sense of urgency. However, we recently encountered a case in which proximal subintimal dissection occurred secondary to shunt insertion, which resulted in a postoperative neurologic deficit. We present the case, with a discussion of the probable cause of dissection and its future prevention.

Sequential bypass grafting for salvage of lower extremities.

Since 1978, 12 patients at our institution have had distal sequential bypass grafting for limb salvage with either polytetrafluoroethylene (PTFE) or reversed saphenous vein and anastomoses to two different distal vessels. Seven patients had had previous vascular operations. One patient died of a stoke in the early postoperative period; a second patient, who was lost to follow-up several months after operation, was presumed to have died. Follow-up is otherwise complete (range seven to 48 months), without early or late limb loss. Results are encouraging and suggest that the sequential anastomotic technique may offer improved results in appropriate limb salvage cases with poor distal runoff.

Use of cardiopulmonary bypass for thrombectomy in acute superior vena cava syndrome.

An increasing incidence of nonmalignant, indwelling catheter cases has been reported in relation to superior vena cava syndrome. Such cases may be life-threatening, with rapid development of facial and neck edema and the production of respiratory distress. This is the first reported case of atrial and superior vena caval thrombectomy requiring cardiopulmonary bypass; it is only the second case reported in which operative thrombectomy has been used. Because of the problems associated with an increase in the use of indwelling venous catheters and the satisfactory results we obtained in this case, such an aggressive form of treatment for acute, benign superior vena cava syndrome may be used more frequently in the future.

Coarctation of the abdominal aorta.

Coarctation of the abdominal aorta represents an unusual but surgically treatable form of hypertension. The cause is somewhat controversial but generally can be traced to congenital or acquired origins. A case is presented in which the anomaly appears to be congenital. The variability in anatomy and subsequent treatment are discussed along with appropriate evaluation of the problem.

Myocardial fibroma or fibrous hamartoma.

Early interest in myocardial tumors was directed primarily at their pathology. Today, however, interest must be in early diagnosis and planned operation utilizing cardiopulmonary bypass since such tumours, both benign and malignant, are potentially lethal due to their location and since most are resectable. The case of a patient with myocardial fibroma presented here offers an expanded pathological picture: the tumor contained fibrous tissue, cardiac muscle, vascular elements, adipose tissue, and smooth muscle. Smooth muscle has not been previously reported. A review of the literature reveals disagreement and confusion over proper nomenclature for the entity. Perhaps its varied histological presentation is better described as fibrous hamartoma than fibroma.

Gastric complications after radiotherapy for Hodgkin's disease and other lymphomas.

Six patients who originally received radiotherapy for Hodgkin's disease or primary gastric lymphoma developed radiation injury of the stomach requiring surgical management. Only two of these patients had evidence of gastric neoplastic involvement at the time of treatment. Experience with these patients leads us to draw the following conclusions: (1) Symptoms of radiation injury mimic those of recurrent neoplastic disease. (2) The effects of radiation are progressive and may be resistant to medical management. (3) The indications for surgical management include perforation, hemorrhage, obstruction, intractable pain, fistula formation, and inability to rule out recurrence. (4) Parenteral hyperalimentation can be an important adjunct in preparing debilitated patients for operation. (5) Gastric resection with gastrojejunostomy is the preferred operation. (6) Frozen section examination can be useful in determining the proper level of resection.