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J R Kramer

Publications and source records attributed to J R Kramer.

At least 19 recordsLinked to original sources
PubMed1992

Characterization of ultraviolet laser-induced autofluorescence of ceroid deposits and other structures in atherosclerotic plaques as a potential diagnostic for laser angiosurgery.

Unstained frozen sections of normal and atherosclerotic human aorta and coronary artery were examined using histochemical and fluorescence microscopic techniques to identify the structures responsible for autofluorescence under 351 to 364 nm laser excitation. These structures included elastin and collagen in normal and atherosclerotic specimens, calcium deposits in calcified plaques, and granular or ring-shaped deposits histochemically identified as ceroid found in both calcified and non-calcified plaques. Qualitatively, both the color and intensity of ceroid autofluorescence differed greatly from that of elastin or collagen. The emission spectra of elastin, collagen, and ceroid were examined by microscopic spectrofluorimetry, and were found to differ significantly as well. When compared with spectra of elastin and collagen, spectra of ceroid were broader, shifted to the red, and were somewhat resistant to bleaching. We conclude that detection of laser-induced ceroid autofluorescence may aid in identifying plaques for laser ablation.

Angioplasty, Laser↗
PubMed1992

Vein graft disease: the clinical impact of stenoses in saphenous vein bypass grafts to coronary arteries.

The influence of coronary artery stenoses on patient survival and event-free survival is known, but no studies have reported the long-term outcome of patients with stenoses in saphenous vein bypass grafts. We retrospectively studied 723 patients who underwent a postoperative angiographic study that documented a stenosis of 20% to 99% in at least one saphenous vein graft and who did not undergo reoperation or percutaneous transluminal coronary angioplasty within 1 year after that catheterization. The mean follow-up interval was 83 months (range 1 to 237 months). For comparison, a group of 573 patients who underwent a postoperative catheterization that did not show any vein graft stenosis were also followed up. Cox regression analyses were used to identify predictors of late survival, reoperation-free survival, and event-free survival. For the entire group of patients with stenotic vein grafts, moderate or severe impairment of left ventricular function (p less than 0.001), interval between operation and catheterization (p less than 0.001), older age (p = 0.001), triple-vessel or left main coronary artery disease (p = 0.004), and stenosis of the vein graft to the left anterior descending coronary artery (p = 0.09) were associated with decreased late survival. Patients with an operation-to-catheterization interval greater than or equal to 5 years were at particularly high risk, and multivariate analyses of that subgroup confirmed that a stenotic graft to the left anterior descending artery was a strong predictor of decreased survival (p less than 0.001), decreased reoperation-free survival (p less than 0.001), and decreased event-free survival (p less than 0.001). Patients greater than or equal to 5 years postoperatively with greater than or equal to 50% stenosis of vein grafts to the left anterior descending artery had survival of 70% and 50% at 2 and 5 years after catheterization, compared with 97% and 80% for those with greater than or equal to 50% stenosis of the native left anterior descending artery (p = 0.002). Late vein graft stenoses are more dangerous than native coronary stenoses. Late stenoses in saphenous vein grafts to the left anterior descending coronary artery predict a high rate of death and cardiac events and are an indication for reoperation.

Cardiac Catheterization↗
PubMed1991

Cardiac catheterization 1990: a report of the Registry of the Society for Cardiac Angiography and Interventions (SCA&I).

This report presents the first year's experience of a totally computerized cardiac catheterization laboratory reporting system, including the results and complications of invasive and interventional procedures. Sixty-three laboratories reported a total of 71,916 patients studied between January 1 through December 31, 1990. Two previous registry reports have been published. Compared with data acquired by previous methods, in spite of an older and sicker population, the mortality for diagnostic procedures has remained remarkably constant (0.11%). The computerized format facilitates data collection and analysis, helps resolve new issues as they arise and serves as a method of monitoring quality of laboratories and individuals.

Adult↗
PubMed1991

476 nm excited laser-induced fluorescence spectroscopy of human coronary arteries: applications in cardiology.

We have shown that normal coronary arteries and noncalcified and calcified atherosclerotic plaque can be differentiated on the basis of the 476 nm excited fluorescence spectra, providing the basis of a spectroscopic guidance system for coronary artery laser angiosurgery. This discrimination is based on extraction of parameters from tissue fluorescence spectra, which are proportional to the tissue concentrations of structural proteins (collagen and elastin) and ceroid via a model of tissue fluorescence. We use these parameters to calculate the likelihood that an area of interest in a coronary artery is normal, noncalcified, or calcified plaque. This method of diagnosing atherosclerosis provides information about the histochemical composition of atherosclerotic lesions and is thus fundamentally different from the diagnostic methods currently used. It may ultimately have bearing on a number of pertinent clinical problems. We have discussed applications to studying initiating factors in formation and progression of plaque, healing after interventional treatments, and the likelihood of restenosis after PTCA.

Algorithms↗
PubMed1990

Ten-year survival of patients with mild angina or myocardial infarction without angina: a comparison of medical and surgical treatment.

Ten-year survival percentages were calculated for groups of 407 initially medically treated patients and for 390 patients who had early coronary bypass surgery; all had either mild angina pectoris or myocardial infarction without subsequent angina pectoris. Uncensored actuarial survival was 77% for medical patients and 83% for the surgical group. For 179 patients who had internal thoracic (mammary) artery grafting as part of their procedures, survival was 91% in contrast to 76% for those who had vein grafts only. A sharp drop of the survival curve for the vein graft group after the seventh year was not shown for those who had internal thoracic artery grafts. Survival was 71% for 280 patients treated medically only.

Angina Pectoris↗
PubMed1989

Alteration of spectral characteristics of human artery wall caused by 476-nm laser irradiation.

Fluorescence spectroscopy is a promising new technique for discrimination of normal and atherosclerotic arterial tissues. It has been suggested that this technique be used as a guidance system for laser angiosurgery catheters; however, irradiation by 476-nm light can change the spectroscopic properties of arterial tissue. We present studies that establish intensity levels and exposure times at which alterations in tissue spectral properties are minimal. We also investigate the nature of spectral alterations following exposure of normal human aorta to high intensities of 476-nm laser light. Changes in laser-induced fluorescence (LIF) are characterized by two prominent features: the peak fluorescence intensity decreases permanently, and the fluorescence lineshape changes in a largely reversible way. We relate these changes to alterations in individual tissue chromophores: permanent changes in absolute fluorescence intensity are due to irreversible changes in tissue fluorophores, reversible changes in fluorescence lineshape are due alterations in tissue absorbers. A simple kinetic model is used to describe the decrease in absolute fluorescence intensity.

Aorta↗
PubMed1989

Late follow-up of 781 patients undergoing percutaneous transluminal coronary angioplasty or coronary artery bypass grafting for an isolated obstruction in the left anterior descending coronary artery.

Seven hundred eighty-one patients with isolated left anterior descending coronary atherosclerosis treated with either coronary artery bypass grafting or percutaneous transluminal coronary angioplasty between January 1980 and December 1984 were studied to determine late survival and event-free survival. Follow-up was complete in 775 patients (99.4%). Actuarial survival at 5 years was 98% for surgical patients and 95% for angioplasty patients (p = 0.02). Five-year event-free survival (freedom from myocardial infarction, bypass grafting, angioplasty, and death) was 93% for surgical patients and 62% for angioplasty patients. This study suggests that the higher initial cost and complexity of bypass surgery may be justified by superior long-term results.

Angioplasty, Balloon, Coronary↗
PubMed1989

Spectral diagnosis of atherosclerosis using an optical fiber laser catheter.

This communication demonstrates that fluorescence spectra of human aorta with good S/N ratios can be collected using an optical fiber laser catheter. The performance of this catheter is compared to a non-fiber optic collection system with an equivalent delivery/collection geometry. For a given sample, fluorescence lineshapes obtained using the two systems are identical; differences in peak fluorescence intensity are related to the different collection efficiencies of the two systems. It is shown that the fluorescence lineshape of arterial tissue depends on the delivery/collection geometry of the detection system, and that this is due to the interaction of absorption and fluorescence within the artery wall. This effect is investigated systematically using a specially designed collection system. Results are analyzed qualitatively using a simple, one-dimensional model of tissue fluorescence. With this analysis, we present design requirements for a collection system in which such geometric effects are eliminated, and show that our optical fiber laser catheter satisfies these requirements.

Aortic Diseases↗
PubMed1989

Argon ion laser-excited autofluorescence in normal and atherosclerotic aorta and coronary arteries: morphologic studies.

Argon ion laser-excited autofluorescence was studied in unstained frozen sections of 47 normal and atherosclerotic human aortas and coronary arteries by means of a bright-field microscope modified for fluorescence microscopy with 476 nm argon ion laser epillumination, and compared to morphology in serial sections stained with H & E, Movat pentachrome, and oil red O. Normal artery autofluorescence correlated morphologically with the structural protein fibers elastin and collagen in the intima, media, and adventitia. Atherosclerotic plaque autofluorescence correlated morphologically with lipid or calcified deposits in the atheroma core. The autofluorescence of these deposits differed from that of elastin and collagen in distribution, intensity, and color, and increased with the severity of the plaque. We conclude that argon ion laser-excited autofluorescence in normal and atherosclerotic arteries correlates with morphology and has diagnostic potential in laser angiosurgery.

Adult↗
PubMed1989

The dynamics of progression of coronary atherosclerosis studied in 168 medically treated patients who underwent coronary arteriography three times.

To study the dynamics of progression of coronary atherosclerosis we analyzed findings in 168 patients who underwent coronary arteriography three times without undergoing coronary surgery or percutaneous transluminal coronary angioplasty. Of 66 patients who had progression in interval 1 (from first to second coronary arteriogram), 32 also had progression in interval 2 (from second to third coronary arteriogram); of 102 patients who had no progression in interval 1, 37 had progression in interval 2. In only 9 of the 32 patients who had progression during both intervals was the same lesion involved, and in six of these patients other lesions were also involved. Progression correlated with the duration of the interval between catheterizations, an increase in symptoms, and the occurrence of myocardial infarction. Analysis of variance showed no significant differences in mean values for age, blood pressure, total serum cholesterol, and serum triglycerides in the four main progression groups. Progression of coronary atherosclerosis is a highly unpredictable process. It follows a nonlinear course, and information derived from sequential coronary arteriograms is of little value in predicting future progression.

Angiography↗
PubMed1989

A one-layer model of laser-induced fluorescence for diagnosis of disease in human tissue: applications to atherosclerosis.

This paper describes a general model of tissue fluorescence which can be used both to: 1) determine chemical and physical properties of the tissue, and 2) design an optimal algorithm for clinical diagnosis of tissue composition. This model is based on a picture of tissue as a single, optically thick layer, in which fluorophores and absorbing species are homogeneously distributed. As a specific example, the model is applied to the laser induced fluorescence (LIF) of normal and atherosclerotic human aorta using 476 nm excitation. Methods for determining the relevant attenuation and fluorescence lineshapes are detailed, and these lineshapes are used to apply the model to data from 148 samples. The model parameters are related to the concentrations of the major arterial chromophores: structural proteins, hemoglobin and ceroid. In addition, the model parameters are used to derive diagnostic algorithms for the presence of atherosclerosis. Utilizing a binary classification scheme, the presence or absence of pathology was determined correctly in 88 percent of cases.

Algorithms↗
PubMed1988

Effects of varying argon ion laser intensity and exposure time on the ablation of atherosclerotic plaque.

Using continuous wave (CW) argon ion laser light, a total of 253 laser exposures of varying power (1.5, 3, 5, 8 or 10 W) and duration (20-1,333 ms) were delivered to four segments of human atheromatous aorta obtained at autopsy. Exposure conditions were controlled by using an optically shielded laser catheter that provided a 500 micron spot of light of known power. Two thresholds for consistently reproducible ablation could be defined-an intensity threshold at 25.5 W/mm2 and a fluence threshold at 3.2 J/mm2. Above threshold, a fluence of 5.1 J/mm2 was found to produce the most efficient ablation, ie, removed the greatest volume (mm3) per energy delivered (J) compared to other fluence levels employed (p less than 0.0001). Between aortic segments, however, considerable variability in efficiency (mm3/J) was observed, possibly owing to different optical properties and/or plaque composition. Low-intensity laser radiation produced inconsistent ablation and extensive coagulation effects to surrounding tissue. When a fluence of 5.1 J/mm2 was constructed with a high-intensity laser beam and a short exposure time, consistent and efficient tissue removal resulted without histologic evidence of coagulation necrosis.

Angioplasty, Balloon↗
PubMed1988

Gas volume quantitation during argon ion laser ablation of atheromatous aorta in blood and 0.9% saline media with an optically shielded catheter.

Using an optically shielded fiber optic laser catheter, the amount of gas produced when firing an argon ion laser into 0.9% saline solution or blood alone and into atheromatous aorta in either a blood or 0.9% saline medium was quantitated. Energies from 0.25 to 4 joules (J) were used at powers of 2, 5, and 8 W. We found that total volume of gas produced is small not only at equilibrium (0.3 +/- 0.1 microliter/J when firing in blood alone and also when ablating aorta in blood or saline media) but also at peak (2.5 +/- 0.2 microliters/J firing in blood alone and 1.0 +/- 0.1 microliter/J or 0.9 +/- 0.1 microliter/J when ablating aorta in saline or blood, respectively). Because these volumes are small, a clinically significant event from a gas embolus is unlikely during intravascular laser ablation of atheromatous plaque in the energy and power range studied. No gas was quantitated when firing the argon ion laser into 0.9% saline solution alone. The peak gas volume when firing in blood alone was significantly greater than that produced in the other chamber environments. This is thought to be due to increased absorption of argon laser light by hemoglobin. The gas volumes produced by lasing aorta in 0.9% saline or blood were not statistically different.

Angioplasty, Balloon↗
PubMed1979

It works better when problems are shared. Interview by Mark Perlberg.

In an exclusive interview, Jeannette R. Kramer, a specialist in the provision of long-term care, discusses the concept of the therapeutic community that she and her husband have instituted in the skilled nursing care facility that they own and operate. By providing an environment in which patients, their families, and the staff can communicate easily, the nursing facility can pinpoint problems and solve them early.

Communication↗
PubMed1979

Routine coronary angiography prior to elective aortic reconstruction: results of selective myocardial revascularization in patients with peripheral vascular disease.

Routine coronary angiography to determine the prevalence of severe coronary artery disease (CAD) has been recommended to all patients under consideration for elective peripheral vascular reconstruction at the Cleveland (Ohio) Clinic since April 1978. Those found to have severe, correctable CAD have been advised to undergo myocardial revascularization prior to performance of elective peripheral vascular operations. Forty-one of the 68 patients with abdominal aortic aneurysms (AAA) and 26 of the 71 patients with aortoiliac occlusive arterial disease (AI) had clinical evidence of CAD; coronary angiography demonstrated severe, correctable CAD in 23 patients with AAA and in 14 patients with AI. Twenty-seven patients with AAA and 45 patients with AI had no clinical evidence of CAD; severe, correctable CAD was found in six patients with AAA and in six patients with AI. Ninety-six patients, including 26 who had staged cardiac procedures performed, have had elective aortic reconstruction, with one operative death.

Adult↗