John A. Walker

Relation of Lipoprotein Subclasses as Measured by Proton Nuclear Magnetic Resonance Spectroscopy to Coronary Artery Disease

Although each of the major lipoprotein fractions is composed of various subclasses that may differ in atherogenicity, the importance of this heterogeneity has been difficult to ascertain owing to the labor-intensive nature of subclass measurement methods. We have recently developed a procedure, using proton nuclear magnetic resonance (NMR) spectroscopy, to simultaneously quantify levels of subclasses of very low density (VLDL), low density (LDL), and high density (HDL) lipoproteins; subclass distributions determined with this method agree well with those derived by gradient gel electrophoresis. The objective of the current study of 158 men was to examine whether NMR-derived lipoprotein subclass levels improve the prediction of arteriographically documented coronary artery disease (CAD) when levels of lipids and lipoproteins are known. We found that a global measure of CAD severity was positively associated with levels of large VLDL and small HDL particles and inversely associated with intermediate size HDL particles; these associations were independent of age and standard lipid measurements. At comparable lipid and lipoprotein levels, for example, men with relatively high (higher than the median) levels of either small HDL or large VLDL particles were three to four times more likely to have extensive CAD than were the other men; the 27 men with high levels of both large VLDL and small HDL were 15 times more likely to have extensive CAD than were men with low levels. In contrast, adjustment for levels of triglycerides or HDL cholesterol greatly reduced the relation of small LDL particles to CAD. These findings suggest that large VLDL and small HDL particles may play important roles in the development of occlusive disease and that their measurement, which is not possible with routine lipid testing, may lead to more accurate risk assessment.

Coronary artery occlusion and blood lipids

Abstract A possible correlation between the levels of plasma cholesterol and triglycerides and the extent of coronary artery occlusion as determined by angiography was studied in 481 male patients. In older patients (over 58 years of age), a pronounced coronary occlusion was frequently found at plasma cholesterol levels which could be considered normal for that age; while in the younger group (less than 48 years of age), extensive occlusive disease was mainly seen in the presence of elevated plasma cholesterol levels. The correlation between plasma triglyceride levels and coronary occlusion seemed to be less pronounced than was the case with plasma cholesterol levels. However, in patients with low cholesterol levels, an increase of plasma triglycerides was associated with more severe occlusive disease.

Late Results of Saphenous Vein Bypass Grafting for Myocardial Revascularization

Abstract Data from three large groups of patients undergoing aorta-to-coronary artery saphenous vein bypass grafting with follow-up angiograms between 0 and 32 months and postoperative clinical evaluation for up to 46 months enable us to say there is an early saphenous vein closure rate of 9%. These closures are probably related to technical judgment difficulties and lend themselves to improvement in results. The documented late closure rate in 92 patients followed a mean of 31.7 months was 13%. This is a rate of one late closure per 171 patient-months. Of the 92 patients, 80 had some effective vein graft functioning in this follow-up period. Histological evaluation has revealed subintimal fibrous hyperplasia to be the predominant factor involved in late closure of the vein bypass. Its manifestations are variable, and the multifactorial etiology is as yet unclear. Since 5% of vein grafts have some significant subintimal fibrous hyperplasia at the time of insertion, only close follow-up with correlation of operative, angiographic, and histological data will provide the answers to the question of etiology of late vein graft closure. Studies on the effect of trauma, vascularity, and nutrition of vein grafts are necessary. The answer to this problem will be necessary to set the coronary vein bypass procedure on a firm footing in the treatment of coronary artery disease.

Endomyocardial Fibrosis: A Surgical Approach

Abstract Endomyocardial fibrosis (EMF), a disease encountered in tropical areas, characteristically in Uganda, produces progressive endocardial restriction, heart failure, and ultimately death. To the present time no treatment has been effective in controlling the evolution of the process. The case of a young girl with EMF and unrelenting congestive heart failure is presented. Following an open-heart operation with excision of the fibrotic endocardium and replacement of the mitral valve, the patient is asymptomatic and has resumed normal life. This is the first case of endomyocardial fibrosis treated successfully and illustrates the feasibility of a new therapeutic approach to the entity. Open-heart operation should be considered in patients affected by this lethal disease.

Trends during 25 years of coronary artery bypass operation at St. Luke’s Medical Center in Milwaukee, Wisconsin

BACKGROUND Most studies of changes in coronary artery bypass graft (CABG) operations are from major academic institutions. The present study evaluated changes in CABG operations since 1968 in a community hospital. METHODS The data were from the St. Lukes Medical Center Cardiovascular Data Registry in Milwaukee, Wisconsin. Mortality rates, risk factors, overall patient risk, and surgical procedures were compared from 1968 to 1994. RESULTS There was a dramatic decrease in 30-day mortality rates from 1968 to 1972. After 1976, mortality rates increased because of higher risk patients, but the mortality rate, adjusted for patient risk, continued to decline. Both internal mammary arteries and sequential grafts were widely used by 1972, followed by a decline in use until 1980, and then a steep increase in use from 1980 to the present. CONCLUSIONS This study provided evidence from a community hospital that the skills of the surgical teams improved first dramatically then gradually. The pattern of adapting new surgical techniques suggested that these techniques were critically evaluated for several years after they were introduced.

Low-density lipoprotein particle size is not a discriminating marker for atherogenic risk in male offspring of parents with early coronary artery disease☆

The aim of this study was to assess the importance of low-density lipoprotein (LDL) particle size as a marker of atherogenic risk in male offspring of a parent with early coronary artery disease (CAD) before the age of 60 years. CAD-positive (CAD+) offspring were recruited into two groups based on age, 15 to 30 years (n = 20) and 31 to 45 years (n = 41), and matched to CAD-negative (CAD-) offspring by age and body mass index (BMI) (n = 20 and 21 per group). LDL peak particle diameter was assessed by polyacrylamide gradient gel electrophoresis. There was no significant difference in LDL peak particle diameter between CAD+ and CAD- offspring (26.2 +/- 0.1 v 26.2 +/- 0.1 nm, mean +/- SE). There was also no difference between CAD+ offspring and CAD- offspring when comparisons were made within their own age group (26.5 +/- 0.1 nm in younger CAD+ offspring v 26.2 +/- 0.1 nm in younger CAD- offspring, and 26.0 +/- 0.1 nm in older CAD+ offspring v 26.1 +/- 0.2 nm in older CAD- offspring). Peak particle diameter was significantly greater in younger CAD+ offspring than in older CAD+ offspring (26.5 +/- 0.1 v 26.0 +/- 0.1 nm, P < .05). We conclude that small LDL particle size is not a discriminating marker for early atherogenic risk, and that measurement of LDL particle size has limited value in the assessment of coronary risk, at least in the age ranges we studied.

The Relation Of Documented Coronary Artery Disease To Levels Of Total Cholesterol And High-density Lipoprotein Cholesterol

Recommendations for identifying persons at high risk for coronary heart disease are based primarily on levels of total and low-density lipoprotein cholesterol. We examined whether, given knowledge of these levels, information on the high-density lipoprotein cholesterol level would improve the prediction of arteriographically documented coronary artery disease among 591 men. We found that even at levels of total and low-density lipoprotein cholesterol considered desirable, high-density lipoprotein cholesterol was inversely related to disease severity. For example, among the 112 men with a total cholesterol level <180 mg per dl, the mean occlusion score (representing the overall severity of disease) was 107 among men with a high-density lipoprotein cholesterol level ≤30 mg per dl vs a mean score of 52 among men with levels ≥45 mg per dl. Furthermore, men with low levels of both low-density lipoprotein cholesterol (<110 mg per dl) and high-density lipoprotein cholesterol (≤30 mg per dl) had as much occlusive disease as did men with high levels of both lipoprotein fractions. Given information on the ratio of high-density lipoprotein cholesterol to total cholesterol, the actual levels of the lipoprotein fractions did not improve disease prediction. Our results emphasize the importance of considering high-density lipoprotein cholesterol when assessing coronary heart disease risk.

Scanning laser system for combined fluorescent diagnostics and photodynamic therapy: structural design, preliminary trials, and potentials

Photodynamic therapy (PDT) is commonly performed by administration of porphyrin photosensitizers selectively retained by malignant tumors. Subsequent photoexcitation with UV-blue light causes fluorescence useful for diagnosis. Excitation by red light destroys the cancer tissue. The use of high-speed scanning of laser light as an alternative to conventional PDT which employs dispersed light to achieve uniformity of treatment is proposed. It is shown that treatment with scanned light beams produces photochemical effects in malignant animal tissue that are virtually the same as those caused by comparable treatments with diffused light. It is argued that undesirable thermal effects can be reduced by the use of focused, scanned laser beams in lieu of diffused light. It is also shown how concurrent analysis and treatment can proceed using a system of two laser beams. >

Risk factors and coronary artery obstruction in male and female patients with aortocoronary bypass operation.

In order to learn about some possible reasons for the low proportion of women among the patients with aortocoronary bypass operation (12-20%) we have compared the prevalence of hypertension, hyperlipidemia, history of smoking and chest pain in 110 women and 813 men with this surgical intervention. In spite of the similar or even higher prevalence of abnormal risk factors, the women patients showed less extensive coronary artery impairment than the male patients indicating their higher tolerance of the risk factors and lesser need for the bypass operation.

Congenital heart disease in adults

Abstract A series of forty-one patients who have attained adulthood despite significant hemodynamic congenital heart defects is presented. Thirty-four have undergone open heart methods and seven, closed heart procedures. Only one death occurred in the series, a mortality of 2.4 per cent. Two patients had complications but survived. All patients but one have returned to full occupation and are asymptomatic. We believe that every patient with hemodynamically significant heart disease should undergo repair regardless of age.